mining net

Pertambangan Batubara: Pro dan Kontra

2008-09-17T21:35:00.000-07:00

Indonesia adalah eksportir batubara terbesar kedua di dunia (setelah Australia, 2006). Batubara yang banyak diekspor adalah batubara jenis sub-bituminus yang dapat merepresentasikan produksi batubara Indonesia. Produksi batubara Indonesia meningkat sebesar 11.1% pada tahun 2003 dan jumlah ekspor meningkat sebesar 18.3% di tahun yang sama. Sebagian besar cadangan batubara Indonesia terdapat di Sumatra bagian selatan. Kualitasnya beragam antara batubara kualitas rendah seperti lignit (59%) dan sub-bituminus (27%) serta batubara kualitas tinggi seperti bituminus dan antrasit (14%).

Sekitar 74% dari batubara Indonesia merupakan hasil penambangan perusahaan swasta. Satu-satunya Badan Usaha Milik Negara (BUMN), PT Tambang Bukit Asam, menghasilkan sekitar 10 Mt (hanya 9% dari total produksi batubara Indonesia pada tahun 2003) dari penambangan terbuka. Bandingkan dengan perusahaan-perusahaan swasta seperti PT Adaro, PT Kaltim Prima Coal, serta PT Arutmin yang dapat memproduksi batubara hingga di atas 10 Mt pada tahun yang sama. Terlihat ironis bukan? Perusahaan penambangan batubara milik negara kalah produksi oleh perusahaan swasta.

Operasi penambangan batubara seringkali dituduh menyebabkan kerusakan lingkungan. Penambangan batubara diperkirakan menyebabkan kerusakan pada kurang lebih 70 ribu hektar tanah. Pada beberapa area, limbah cair dibuang pada sungai terdekat yang pada akhirnya mencemari sumber air warga sekitar. Dampak lingkungan serta permintaan akan kontribusi perusahaan pertambangan yang lebih besar kepada perkembangan masyarakat telah menyebabkan munculnya permintaan akan ditutupnya operasi penambangan batubara. Salah satu hal yang dapat dilakukan untuk mengurangi pengrusakan lingkungan oleh operasi penambangan batubara adalah dengan lebih memperketat regulasi yang berkaitan dengan penambangan batubara, disinilah peran besar pemerintah. Pemerintah merespon permasalahan ini dengan memberikan komitmen bahwa operasi penambangan batubara akan merujuk pada peraturan pemerintah mengenai keselamatan lingkungan. Sebagai contoh, pada tahun 1999 diterbitkan PP no 18 yang mengatur mengenai tata cara pemrosesan limbah berbahaya dan beracun. Peraturan ini mengharuskan perusahaan pertambangan untuk memproses limbah yang dihasilkan hingga mencapai derajat kebersihan yang sangat tinggi dengan standar kemurnian air yang 5 kali lebih ketat dibandingkan Amerika Serikat maupun Kanada. Akan tetapi, penerapan regulasi ini pada akhirnya ditunda karena pemerintah mengevaluasi ulang kemampuan teknologi yang dimiliki oleh perusahaan pertambangan di Indonesia dan ternyata dibutuhkan penyesuaian. Belum lagi adanya penambangan batubara ilegal. Para penambang ilegal mengabaikan ketentuan yang berkaitan dengan lingkungan dan keselamatan serta menjual batubara dengan harga yang lebih rendah. Pemerintah diharapkan dapat mengambil sikap dan menuntut para penambang ilegal ini.

Pemerintah sendiri memiliki ketertarikan yang besar dalam mengembangkan teknologi pemanfaatan batubara untuk mengurangi dampak lingkungan yang ditimbulkan oleh batubara. Usaha untuk mengembangkan Clean Coal Technology (CCT) telah memasukkan kerjasama dengan pihak asing untuk mempelajari efek-efek yang mungkin muncul dari penggunaan batubara dan untuk mencari cara baru agar pembangkit listrik yang berbasis pembakaran batubara dapat memenuhi ketentuan lingkungandari segi emisi. Ini suatu itikad baik yang ditunjukkan oleh pemerintah mengingat permasalahan yang menyangkut emisi yang dihasilkan oleh batubara dapat mengurangi visibilitas digunakannya batubara sebagai sumber energi.

Masalah sumber energi pun sedang menjadi fokus utama pemerintah berkaitan dengan naiknya harga minyak bumi. Pada dasarnya, cadangan batubara Indonesia memang jauh lebih besar dibandingkan dengan cadangan minyak bumi maupun gas alam sehingga pemerintah kini mulai melihat batubara sebagai sumber energi alternatif yang murah. Batubara selama ini telah digunakan sebagai bahan bakar pada pabrik semen dan pabrik baja, apa salahnya jika batubara digunakan untuk membangkitkan listrik? Apabila hal ini dapat dilakukan, subsidi pemerintah untuk BBM dapat berkurang (saat ini subsidi memang tidak mencukupi akibat kenaikan harga minyak bumi dan peningkatan konsumsi BBM). Dalam 3 tahun mendatang diharapkan telah berdiri PLTU Batubara dengan kapasitas daya listrik yang dapat dihasilkan sebesar 10000 MW.

Tampaknya untuk mewujudkan hal itu, pemerintah dan industri pertambangan batubara harus bekerja lebih keras. Dengan perkiraan heating value batubara Indonesia yang berada pada kisaran 5000 sampai 7000 kal/kg, berapa banyak batubara yang harus diproduksi untuk menghasilkan listrik 10000 MW? Apakah perusahaan pertambangan di Indonesia dapat menemukan cara untuk menambang batubara tanpa menimbulkan kerusakan lingkungan?

Tampaknya jawaban pertanyaan di atas adalah TIDAK. Atau mungkin BELUM. Tanah yang dikeruk, polusi yang disebabkannya, serta bekas yang ditinggalkannya masih akan menjadi masalah lingkungan di kemudian hari. Mungkin saat ini yang bisa dilakukan adalah meningkatkan kinerja unit-unit penanganan limbah sekaligus melakukan transfer teknologi terkait dengan keterbatasan yang kita miliki dalam teknologi penambangan, mengurangi penambang-penambang ilegal, dan secara bertahap melakukan rehabilitasi lahan pertambangan yang telah ditinggalkan. MENGAPA? Karena lebih tidak mungkin menghentikan penambangan batubara yang saat ini diharapkan bisa menjadi penyelamat bagi krisis energi yang melanda Indonesia.

by Ratih Asthary

CLASSIFICATION AND CHOICE OF MINING METHODS

2008-01-15T18:19:00.000-08:00

Programme of Study and Description of Mining Methods

To give a sufficiently full characterization of a mining methods actually employed or planned, one should study it and, if necessary, describe it in many of its aspects. The pertaining data and characteristics may be classified into the following groups.

I. Mining and Geological Conditions

Name of the mineral extracted. Shape of the deposit-bed, sheet like deposit, placer, vein, etc. Thickness of the deposit ( true and lateral ), prevalent thickness, maximal and minimal deviations. Angle of dip and its variations. Pitch or hade of the ore body. Area of the horizontal section of the deposit. Typical geological faults and disturbances in the attitude. Matter composition of the minerals. Distribution of useful components in the deposit. The nature of the contact between the deposit and the country rocks surrounding it. Hardness, jointing and firmness of the mineral. Its density ( volume or unit weight ). Size distribution and ability to compact. Petrographic characteristics of enclosing country rocks. Their hardness, jointing and stability. Abudance of water in the deposit. Properties of the mineral’s self-ignition. Oxidability of the ores subject to flotation. Evolution of noxious gases. Harmful properties of dust ( explosiveness of coal and sulphide dust, dangerous properties of quartz dust with respect to silicosis ).

II. Mining Characteristics of the Method To Be Adopted in Working a Deposit

Designation of the mining method. Level interval. Sublevel interval. Extent of the working section or block on strike. Size of pillars and support pillars. Slice thickness. Cross-section and support of development openings. Sequence of driving development openings. Advance rate of faces. Rate of development headings advance over that of production faces. Order of recovery of mineral reserves in a working section or block. Order of mining sublevels, pillars or slices. Shape and size of working faces. Their interlocation. Advance direction of working faces. Method of stoping. Methods of controlling enclosing rocks ; by support pillars, timbering, filling ( complete, partial ), shrinkage stoping, caving ( spontaneous or induced ), or by different combinations of these methods. Methgrizzly levels ( in ore mining ). Ventilation of development and productive workings. Lighting of mine workings. Measures envisaged by the system of mining against penetration of water and inrushes of water-bearing rocks. Preventive measures against underground fires, as part of the mining method adopted.

III. Mechanisation of Mining Operations

Brief specifications of machines (trade-mark, capacity, ratings of driving motors and overall dimensions) used for drilling holes, undercutting and breaking the mineral or country rock: drilling machines, electric augers, drill-wagons for the underground boring of deep blast-holes and large diameter holes; coal cutters, cutting and loading machines(combines), coal planers, hydraulic giants(in hydraulicking),etc. analogous information on machines and equipment employed for the transportation of the mineral and waste: conveyers, scrapers, loading machines, mine car spotting tugger hoists, district electric locomotives, capacity and overall dimensions of mine cars. Machines and mechanical plants for ventilation and mine drainage(needed for the system of mining).

IV. Organisation of Work

Organisation of operations in the faces of development and productive workings. Graphs (planograms) of cyclic operation and labour distribution charts(number of miners, number engaged in each shift and classes of work performed). Advance rate of faces per cycle or round. Number of cycles or rounds per day and per month. Coordination of all operations for the whole of the producting section( linked with the system of mining ).

V. Techincal and Economic Characteristics of the Mining Method

Mineral output in productive and development workings per day per shift, in individual faces ( walls, stopes ) and in the section as a whole. Monthly tonnage produced by the entire section. ( If, because of features specific to the adopted method, the tonnages tend periodically to very widely, for instance, during shrinkage-stoping and subsequent drawing of the ore, the characteristics above must be given for individual stages of mining ). Yield of the mineral from development and working faces(for the whole of the mining method in per cent). Mining of working losses of the mineral( in per cent ). Degree of dilution (in per cent to the total content of valuable components in undiluted ore). Time required for the recovery of the aggregate reserves in the working section or block. Output per faceman and per miner for the whole of the section (in tons of mineral, or in cu m of ore, or ore and barren rock together per shift). Explosives consumption per ton, or per cu m in grammes. Mine timber consumption per 1,000 tons or 1,000 cu m of the mineral, or the aggregate amount of the mineral and waste. Electric power and compressed air consumption per ton or cu m. mining cost of a ton or cu m of the mineral, or of the mineral and waste together for the whole of the producting section, including delivery to the haulageway.

Classification of Mining Methods

Methods employed for mining solid minerals in deposits may be divided into the following principal groups :

I. Underground mining.

II. Surface mining.

III. Combined mining.

IV. Special methods of mining.

No explanations are needed for singling out methods I and II. One example of method III is mining by glory holes, when the mineral is extracted by the opencast method and loaded into transport vehicles and subsequently hauled in underground workings.

Special methods include those in which actual mining is characterized by changes in the native state of the extracted mineral. They include underground coal gasification, ore-mining by underground leaching, extraction of sulphur through boreholes by evaporation, etc.

As we have seen, the systems used in mining solid minerals by the underground method vary widely and are frequently complex. For a more or less full characterization, one should refer to many of the features enumerated above.

However, the classification of mining methods cannot be founded on all the above-cited, extremely numerous features. Their classification should be based only on the especially important and typicalfeatures, according to which it is advisable to divide and single out the systems of mining.

Most of the hitherto proposed classifications of mining methods were based on methods of controlling enclosing rocks and on the arrangement of development openings.

It is noteworthy in this connection that the division of mining methods into groups according to the arrangement of development openings is generally adopted both for drawing up classifications and for working coal and other sheet deposits, whereas the classifications for the systems applied in mining ore deposits are founded on the second principle-that involving the method of enclosing rock control. This difference in the approach to the characteristic features, on which the classification is based, is by no means accidental or one chosen arbitrarily by the compilers of the classification, but is explained by the fact that for the sheetlike deposits the arrangement of development openings is very typical and at the same time simple and convenient because of their regular shape.

Choice of Mining ethod

The description of the principal methods of mining enumerated the conditions most suitable for each. But since the combinations of diverse factors in enfluencing the selection of a mining method may be extremely variable, this choice for a particular deposit is complicated by its geological features, as well as by the mining and economic situation.

The method selected must meet the basic demands of the conditions in which it is called to operate.

In a very general outline the method of the choice itself boils down to comparing the features of each one of the mining systems which may possibly be employed in actual geological, mining and economic conditions.

Bentang alam Pantai

2008-01-15T18:11:00.000-08:00

Bentang alam pantai dikontrol oleh aksi alamiah yang bekerja secara terus menerus. Pada dasarnya dapat dikelompokkan dalam dua macam aksi alamiah yaitu yang bersifat menghancurkan (destruktif) dan yang bersifat membangun dengan cara pengendapan (konstruktif).

Pantai merupakan daerah yang terletak dibagian tepi dari continental (dataran). Yang sangat berpengaruh terhadap pembentukan model pantai adalah gelombang (wava) dan arus (current), sedangkan gelombang pasang surut (tides) kecil pengaruhnya. Gelombang terbentuk antara lain karena adanya pergerakan angin, besar kecilnya kecepatan angin berpengaruh terhadap besar kecilnya gelombang.

Gempa bumi bawah laut, longsor dasar laut dan letusan gunung api bawah laut dapat menimbulkan gelombang besar yang sangat berpengaruh yang disebut tsunami. Arus berbeda dengan gelombang, arus mempunyai pergerakan menerus sedangkan gelombang tidak. Dalam perkembangan selanjutnya pantai dapat tererosi oleh gelombang dan arus dapat mengalami pelarutan dan korasi.

Daerah pantai yang masih mendapat pengaruh air laut dibedakan menjadi tiga bagian, yaitu :

1. Beach (daerah pantai)

Yaitu daerah yang langsung mendapat pengaruh air laut dan selalu dapat dicapai oleh pasang naik dan pasang turun.

2. Shere line (garis pantai)

Jalur pemisah yang relatif berbentuk baris dan merupakan batas antara daerah yang dicapai air laut dan yang tidak bisa dicapai.

3. Coast (pantai)

Daerah yang berdekatan dengan laut dan masih mendapat pengaruh air laut.

Klasifikasi Pantai

Pantai diklasifikasikan dalam dua kelompok yaitu:

Klasifikasi pantai menurut Jonhson, (1919) berdasarkan genesa terbentuknya pantai.
Klasifikasi pantai menurut Shepard (1948) berdasarkan faktor yang berhubungan dengan pembentukannya dan perbedaan bentuk awal dan bentuk berikutnya.

Batu Hijau Copper-Gold Mine, Indonesia

2007-12-26T17:54:00.000-08:00

Batu Hijau copper-gold mine is located on the Indonesian island of Sumbawa in the province of West Nusa Tenggara, 1,530km east of Jakarta. The Contract of Work for the project is held by PT Newmont Nusa Tenggara (PTNNT), a company owned by Newmont Indonesia Ltd (USA, 45%); Nusa Tenggara Mining Corporation (Japan, 35%) and PT Pukuafu Indah (Indonesia, 20%). Newmont is the project operator and has a 52.875% equity stake. Construction of the mine and its associated infrastructure was completed in 1999, after PTNNT had spent ten years exploring the resource, with commercial production beginning in 2000. The operation continues to be one of Newmont’s lowest cost assets. In 2005, copper sales fell 16.2% to 259,780t (2004= 310,000t) at an applicable cost of $0.53/lb and an average realised price before TRCs of $1.45/lb. However, consolidated gold sales rose to 720,500oz at applicable costs of $152/oz, as compared with 715,000oz in 2004. Power for the project is supplied by a 120MW coal-fired plant supported by nine diesel generators. GEOLOGY AND RESOURCES "During 2005, Batu Hijau produced and shipped 1.1Mt of copper concentrate containing 325,500t of copper and 719,000oz of gold." Bata Hijau is a major gold-rich porphyry copper deposit typical of the islands of southeast Asia. These gold-rich porphyries are overwhelmingly hosted by composite stocks of diorite to quartz-diorite and, to a much lesser degree, more felsic compositions such as tonalite and monzogranite. The deposits tend to be characterised by a strong correlation between the distribution of copper sulphides (chalcopyrite and bornite) and gold as the native metal in addition to having a notably higher magnetite content. Gold typically occurs as minute (<10-15> As of the end of 2005, Batu Hijau had an ore reserve containing 2.77Mt copper with 0.69g/t gold. At current production rates, mining should continue until 2025. MINING AND MILLING Batu Hijau is an open-pit mine. Ore is transported to the primary crushers using P&H 4100 electric mining shovels and a fleet of 220t-capacity Caterpillar 793C mechanical-drive haul trucks. The mine typically handles around 600,000t/d of ore and waste, the ore grading an average 0.49% copper and 0.39g/t gold. Following primary crushing, the ore is transported to the concentrator by an overland conveyor, 1.8m wide and 6.8km long. The concentrator circuit consists of two-train SAG and ball mills, followed by primary and scavenger flotation cells, vertical regrind mills and cleaning flotation cells to produce a copper-gold concentrate grading 32% copper and 19.9g/t gold. Counter-current decantation thickeners are used to dewater the concentrate to a slurry, which is pipelined 17.6km from the plant to the port at Benete. Here it is dewatered further, then stocked in an 80,000t-capacity storage area prior to shipment by sea. PRODUCTION During 2005, Batu Hijau produced and shipped 1.1Mt of copper concentrate containing 325,500t of copper and 719,000oz of gold. TAILINGS DEPOSITION The tailings from the operation flow by gravity from the process plant to the ocean where they are deposited 3km from the coast at a depth of about 108m. From there, the tailings, which are non-toxic and non-hazardous, migrate towards the Java Trench and are ultimately deposited at depths in excess of 4,000m. ENVIRONMENT There are considerable environmental challenges at Bata Hijau, including steep terrain and widely dispersed facilities stretching over 40km. The site has a tropical monsoonal climate with high rainfall, and an extended arid season with almost no rainfall. Other environmental considerations include significant seismic activity, with the associated risk of tsunamis, and acid rock drainage, not to mention the existence on site of an endangered species, the yellow-crested cockatoo. Considerable environmental controls are in place, and Newmont reported the operation improved its ‘five-star’ environment rating to four stars in 2005. From : Mining-Technology.com		Batu Hijau is located on the Indonesian island of Sumbawa. Minahasa, also shown on the map, is another Newmont operation.
		Aerial view of the Batu Hijau open pit.
		Blasting in the open pit.
		Haul trucks moving ore at Batu Hijau.
		Aerial view of the concentrator at Batu Hijau.
		The mine's dedicated port facilities at Benete Bay.
		Reclamation reseeding through geotextiles used to prevent erosion of the ground surface by the weather.

Coal Mountain Coal Mine, British Columbia, Canada

2007-12-26T17:48:00.000-08:00

Situated 30km south east of Sparwood, in south-eastern British Columbia, the Coal Mountain metallurgical/thermal coal mine produces metallurgical and thermal products for international steelmakers and other industries.

Formerly owned by Esso Resources Canada Ltd, and operated by its Byron Creek Collieries subsidiary, Coal Mountain was acquired by Fording Coal in 1994. In 2003, ownership of Coal Mountain was transferred to the Elk Valley Coal Partnership, now 60% owned by Fording Canadian Coal Trust and 40% by the major Canadian mining company, Teck Cominco.

Elk Valley Coal is the world's second-largest supplier of metallurgical coal, with an output in 2004 of a near-capacity 24.9Mt.

"Enhancements to the processing plant have improved plant yield while allowing greater flexibility in controlling coal quality."

After purchasing the mine, Fording embarked on a major mobilisation and upgrading programme that included preproduction stripping, exploration, the purchase of larger, more efficient mining equipment, and significant modifications to the processing plant.

Coal Mountain now has a mine capacity of 2.7Mt/y while its washing plant can handle up to 3.5Mt/y of run-of-mine coal. Its actual output in 2006 was 2.0Mt, down from 2.3Mt in 2005 and 2.5Mt in 2004.

GEOLOGY

As with the neighbouring Elk River coalfield to the north, coal resources in the Crowsnest district are hosted in rocks of the jurassic Kootenay formation. The strata have been extensively folded and faulted, a factor that has helped increase the apparent thickness of seams in some areas. Resources at Coal Mountain are generally of mid-volatile bituminous rank.

As of end-2006, the mine's proven reserve totalled over 26Mt of clean coal, with a further 111Mt of measured and indicated resources. These are contained within three coal horizons, the largest being the Mammoth seam, which varies from 1m to 200m in thickness across the property. Reserves are adequate to support mining for at least 13 more years at the production rate achieved in 2006.

MINE AND PROCESS PLANT OPERATION

Open-pit mining is used at Coal Mountain. Overburden stripping and coal production rely on a shovel-and-truck operation. The principal excavators are two O&K RH200 hydraulic shovels with 21 and 26m³-capacity buckets and a LeTourneau 21m³ wheel loader. These are used to load overburden and interburden into the operations' fleet of 136t- and 218t-capacity haul trucks.

Enhancements to the processing plant, including the addition of the most up-to-date process control technology, have improved plant yield while allowing greater flexibility in controlling coal quality.

In common with Elk Valley Coal's other operations in British Columbia and Alberta, Coal Mountain's washing plant has an automated sampling system on its product stream. Online neutron-activated ash and moisture analysers are used to provide data that permits the plant's operators to monitor and tightly control product quality.

PRODUCT TRANSPORTATION

The loading process at all of Elk Valley Coal's operations is monitored by a central computer which controls the automated system. Rail cars can be loaded to within 0.5% of their capacity to prevent over- or under-loading.

"Elk Valley Coal is the world's second-largest supplier of metallurgical coal."

Access to its parent company, Canadian Pacific's, rail system and the export port at Roberts Bank provides Elk Valley Coal with one of the lowest cost transport systems in the world, on a per-tonne-per-kilometre basis. CP Rail uses 112-wagon unit trains to handle Fording’s output, making a round trip over the 1,175km-long journey from the south-eastern BC mines to the coast in around 85 hours.

Roberts Bank, operated by Westshore Terminals, has an annual throughput capacity exceeding 22Mt and is the largest coal-loading port on the west coast of North America. Elk Valley Coal has over 600,000t of storage capacity at Roberts Bank, where the loadout can accommodate bulk carriers in excess of 250,000dwt.

Elk Valley Coal also ships coal east by rail to Thunder Bay terminals at the port of Thunder Bay, Ontario, while direct rail links to the central and eastern USA provide further access to important markets for the company.

COAL QUALITY

Typical quality parameters for Coal Mountain products are:

	Mid-volatile PCI coal	Mid-volatile steam coal
Ash (%)	10.0 – 11.5	15.0 – 17.0
Volatile matter (%)	21.0 – 23.0	21.0 – 23.0
Sulphur (%)	0.3 – 0.4	0.3 – 0.5
Heating value (MJ/kg)	29.3 – 31.0	26.0 – 28.0

From : Mining-Technology.com

Location of Coal Mountain.

Landscape of Coal Mountain.

Typical cross-section at Coal Mountain operations.

Coal Mountain processing plant.

Trucks and loader.

Canadian Pacific Railway Co’s 112-car unit trains to transport its products to tidewater.

Westshore terminals, with an annual throughput capacity exceeding 22Mt.

Lomas Bayas Copper Mine, Chile

2007-12-26T17:39:00.000-08:00

he Lomas Bayas copper mine is in the Atacama Desert of north Chile in the San Cristobal mountains. The mine is at an elevation of 1,500m and lies approximately 110km northeast of the coastal port of Antofagasta. The mine has a workforce of around 390 people. Developed by Westmin Resources Ltd, which spent some $244m on the property, Lomas Bayas was then bought by Boliden before being sold again, this time to Falconbridge, in mid-2001 for $175m. In mid-2006, Xstrata plc bought Falconbridge, with Lomas Bayas now being operated within its copper division. GEOLOGY AND RESERVES The Lomas Bayas orebody is hosted by upper cretaceous volcanic-arc rocks and associated back-arc sediments, which are intruded by an upper cretaceous-paleocene composite granodiorite batholith. The orebody is generally oxidised with a few zones of mixed oxide-sulphide. Copper mineralisation occurs in an irregular concentric zone around a low grade, hydrothermally-altered centre. At the end of 2005, proven and probable reserves at Lomas Bayas totalled 239.2Mt grading 0.36% copper with measured-plus-indicated resources adding up to a further 280.6Mt at 0.28% copper. Inferred resources were 31Mt at 0.3% copper. Lomas Bayas II, as Fortuna de Cobre had been renamed, had a measured-plus-indicated resource of 470.3Mt at 0.29% copper plus 150Mt at 0.21% copper in the inferred resource category. OPEN-PIT MINING Lomas Bayas currently operates one open-pit mine. The orebody has been explored to a depth of 300m and consists of five main mineralised zones structurally controlled by faulting: the Tirana, Candelaria, Andacolla, East and Gordo zones. Key items of open-pit equipment include a P&H 100XP blasthole rig and two P&H 2800XPB electric shovels. Heap-leach grade ore is crushed and placed on leach pads by a series of portable conveyors and a stacking system. Lower-grade, run-of-mine ore is placed directly on separate pads by mine haulage trucks. The mine completed a crusher expansion programme in 2004, increasing its capacity to 36,000t/d of ore. ORE PROCESSING The copper is recovered directly from the ore using a solvent extraction-electrowinning (SX-EW) process. Crushed ore is placed in low heaps built on sloping, impermeable pads for heap leaching and the metal dissolved by repeated application of sulphuric acid solutions. The pregnant solution is collected for copper recovery by electrowinning. Uncrushed run-of-mine ore is leached on separate pads with the pregnant solution also being transferred to the electrowinning circuit. The copper-bearing leacheates are purified by removing metals other than copper using organic solvents, and the copper is then extracted by electrowinning to produce high-quality copper cathodes. These are then transported 120km by truck and rail to the port at Antofagasta for shipment worldwide. PRODUCTION Lomas Bayas was commissioned in mid-1998, when 19,300t of copper were recovered from 2.6Mt of ore mined. Initially, Lomas Bayas experienced considerable difficulty in reaching design capacity owing to higher-than-anticipated levels of chlorides and nitrates that depressed SX performance. After some modifications and a change of SX reagent, Boliden raised output by 16% in 2000. In 2001 performance continued to improve, output totalling 56,300t of copper. The mine produced 62,041t of copper in 2004, a new record and nearly 2,000t more than in 2003. In 2005, its output rose again, to 63,147t. This involved the production and leaching of 13.5Mt of 0.5% copper ore in the heap-leach operation, and 22.4 Mt at 0.22% copper of run-of-mine ore. In March 2004 CMFLB announced a plan to leach copper from dust collected at Noranda's Alto Norte smelter and recover it in the SX-EW facilities. This could add up to 5,000t/y to copper production. ENVIRONMENT Lomas Bayas’ location in the Atacama Desert means that the principal environmental issues are dust control and water management. Water is pumped 135km to the site and the mine has maximised water recycling and conservation. Dust emissions are regularly monitored, the source identified and control strategies devised and implemented. EXPANSION Falconbridge had an option on the Fortuna de Cobre property, adjacent to Lomas Bayas, that had to be exercised by mid-2006. It began a pre-feasibility study during 2005, as well as driving an exploration tunnel into the orebody for bulk sampling purposes. It also built a pilot plant for metallurgical testwork. Mining here would potentially increase the copper output at Lomas Bayas from 60,000t/y to 90,000t/y, or extend the mine’s life by five years to 2020.		Map showing the location of Lomas Bayas and Fortuna de Cobre.
		P&H has also supplied a 100XP blasthole drill to Lomas Bayas.
		Open-pit mining at Lomas Bayas.
		A P&H 2800XPB electric mining shovel, as used at Lomas Bayas.
		The Fortuna de Cobre copper prospect.
		Leachable copper ore from Fortuna de Cobre.

Crandall Canyon Crandall Canyon , USA

2007-12-26T17:35:00.000-08:00

At the end of August 2007, with all efforts having failed to locate the miners missing in the Crandall Canyon mine for more than three weeks – and presumed dead – the US Department of Labor announced an independent investigation to look into the handling of the disaster. The coal mine is located in the north-west of Emery County, 35 miles south-east of Fairview and 15 miles west north-west of Huntington, just off Utah State Route 31 and surrounded by the Manti-LaSal National Forest. The mine permit area extends to over 5,000 acres and occupies fee land as well as federal and state leases, with surface operations being carried out on around ten acres of disturbed land within the forest. The co-owners of the mine are the Intermountain Power Agency (IPA) and UtahAmerican Energy (formerly Andalex Resources) a subsidiary of the Murray Energy Corporation, with Genwal Resources – the operating division of UtahAmerican – responsible for running it. GEOLOGY AND RESERVES The mine is in the Wasatch Plateau coal field, which is characterised by fine to medium grain late Cretaceous grey sandstone, inter-bedded with subordinate light and dark grey carbonaceous shales and coal, with continental and transitional sediments. Further marine sediments lie below the main deposits. "Three major fault zones have been defined within the coal field, running in a north-south direction." Three major fault zones have been defined within this coal field, running in a north-south direction – products of a high angle block fault with extensive minor fracturing within the graben. The trends of these faults have a complex pattern, which cause difficulties for mining efforts in the affected areas. The South Crandall Hiawatha seam, for example, holds up to 12.7 million tons of potentially mineable reserves, but the difficult geology and the thin lenticular coal seam makes getting it out very difficult. The mine produced 1.7 million tons in 2006 and has an estimated recoverable reserve of 13 million tons. MINING Mining began at the Crandall Canyon site in November 1939 and continued using a room and pillar method until September 1955. In 1983, the Genwal Coal Company resumed mining operations, producing an annual total of between 90–210,000t of coal, and in 1989, NEICO purchased the mine. IPA bought a 50% interest the following year. A continuous haulage system was incorporated into the room and pillar method in 1991, which enabled production to rise to 1–1.5 million tons per year. The mine was transferred to Genwal Resources in March 1995 and a longwall system was subsequently installed, which effectively doubled the mine’s capacity. A second new longwall was put in place two years later and a new loadout facility was built at the mine to handle the increased capacity. In 2004, a new low-profile longwall machine – able to cut coal in a seam little more than 5ft (1.5m) thick – was installed. THE COLLAPSE On Monday 6th August 2007, the mine collapsed, trapping six miners 1,500ft (460m) underground, some 3.5 miles (5.5km) from the entrance. The shock waves registered 3.9 to 4.0 by seismographic stations in Utah and Nevada, leading to an initial belief that the collapse had been caused by an earthquake. However, it appears that the collapse happened while miners were engaged in retreat mining – the final stage of a room and pillar operation when the pillars of coal used to hold up an area of the roof are intentionally removed to allow the last of the coal to be recovered. "On Monday 6th August 2007, the mine collapsed, trapping six miners 1,500ft underground" It is an established method of mining, but it is a particularly hazardous one. According to studies by the US National Institutes of Occupational Safety and Health, retreat mining is one of the biggest causes of mine-roof-collapse deaths. Although it accounts for only around 10% of underground coal production, a coal miner is more than three times as likely to be fatally injured by a roof collapse when engaged in this type of mining than any other. Rescue teams were dispatched immediately and began the work of assessing the damage to the mine structure and clearing rubble. On the 9th August, a 2.5in (6cm) hole was bored 1,800ft (549m) towards where the miners were assumed to be trapped. A microphone was lowered and though it did not register any activity, initial samples suggested the air was breathable. Unfortunately, it was later to be established that it was not. A second and larger hole was made at another possible location and a camera used – revealing mining equipment but no miners. A third bore hole was created near to the ventilation area, followed by a fourth targeted towards noises that geophones briefly detected coming from the mine for five minutes on the evening of 15th August. By noon the following day – now 11 days after the collapse – underground rescue teams had only been able to advance around halfway through the rubble; at 6.30 that evening, one of the tunnel walls burst, collapsing the mine again killing three of the rescuers and injuring six others. The remaining rescue teams were pulled from the mine. The fifth, sixth and eventually – at the end of August – seventh bore holes were also all to fail to find either signs of life, or the bodies of the missing miners. Inevitably there has been much criticism voiced, especially of the mine’s owners for ignoring prior safety warnings and the US Mine Safety and Health Administration both for its handling of events and for allowing retreat mining in the first place. "Retreat mining is one of the biggest causes of mine-roof-collapse deaths." With the members of the independent investigation panel – Ernest C. Teaster Jr. and Joseph W. Pavlovich – named at the beginning of September 2007, the process of working out exactly what went so tragically wrong can get underway. Their enquiry is expected to take around six months to come to its conclusions. THE FUTURE The future of the mine seems uncertain and the Utah mining community remains divided over the issue of re-opening it. Murray Energy vice president Rob Moore is reported to have said that the company expected to resume operations "at some point" to access the recoverable coal in other parts of the mine. However, Robert E. Murray, the CEO of Murray Energy, has stated that he has filed the necessary paperwork with federal regulators to permanently close and seal the Crandall Canyon mine. Even before the disaster, although further federal leases were to extend the useful life of the mine and new access ways planned on the south side, the owners had made it clear to the state of Utah that it was their intention that the mine would close in 2008. From : Mining-Technology.com		Satellite view of the Crandall Canyon mine site, just off Utah State Route 31 in the Manti-LaSal National Forest.
		Longwall underground coal production; this technique played a major part in boosting the mine’s production.
		Map showing the extent of the mine.
		A high resolution dual lens camera system waiting to be lowered into an 1,868ft shaft as part of the rescue effort.
		Diagram detailing the boreholes drilled during the rescue attempt.

Brunswick Lead and Zinc Mine, New Brunswick, Canada

2007-12-26T17:32:00.000-08:00

The Brunswick lead/zinc mine, located 35km southwest of Bathhurst, New Brunswick, was formerly owned and operated by Noranda. In June 2005, Noranda merged with its 59%-held subsidiary, Falconbridge, with the ‘new Falconbridge’ being taken over in mid-2006 by the Swiss-based company, Xstrata. Brunswick now operates within Xstrata’s zinc division, producing lead and zinc concentrates with byproduct copper, silver, gold, bismuth, antimony and cadmium. Employing around 800 people, Brunswick treats about 3.6Mt/y of ore, and is the world’s largest underground zinc mine with a cumulative output to the end of 2005 of over 110Mt of ore. Its output is refined at the company’s Brunswick lead smelter and at the CEZinc refinery. GEOLOGY AND RESERVES The ore is contained in up to ten massive sulphide lenses within folded and uplifted lead-zinc, pyrite and copper zones. The metals occur as extremely fine-grained mixtures of chalcopyrite, galena, sphalerite and pyrite, together with gold, silver and other metals. At the end of 2005, proven and probable reserves totalled 14.7Mt grading 0.36% copper, 8.77% zinc, 3.53% lead and 104g/t silver, sufficient for a further four-to-five years’ production. MINING METHOD The 1,125m-deep mine is accessed by a vertical shaft and worked by two methods; the older cut-and-fill method allows the ore to be mined steadily from bottom to top and backfilled with waste rock, leaving a working platform. However, the more efficient open stoping is preferred. Pillars are removed later. Blasted ore is retrieved by remote-controlled load-haul-dump (LHD) machines for transport to ore passes leading to one of the three crushing plants. One recent innovation used is the ‘Weasel’, a unit that can be operated by remote control for drilling and charging blastholes in open stopes. Each crusher has two 1,500t-capacity, run-of-mine ore storage silos. A jaw crusher and two gyratory crushers reduce the ore to minus 150mm before conveyance to the No.3 shaft silos for hoisting to surface in skips. PROCESSING The concentrator design capacity is 10,500t/d of complex lead, zinc, copper and silver sulphide ore. During 2002 an average of 9,560t/d of ore was treated in the mill with a zinc recovery rate of 87.5%. The head grade was around 3.6% lead, 9.7% zinc, 0.36% copper and 105g/t silver. The ore is crushed to –25mm in a cone crusher and stored in fine ore bins (total capacity 9,000t). The subsequent grinding circuit consists of a rod mill from which the outflow passes to hydrocyclones. The rod mill oversize is recycled through a ball mill before re-entering the hydrocyclones. The undersize pulp, containing sphalerite, chalcopyrite, galena, sphalerite/galena combined and gangue minerals, feeds the sequential flotation circuits to produce individual zinc, copper, lead and bulk sulphide concentrates. Zinc is recovered first, with the rougher tailings feeding the copper recovery stage. Copper tailings proceed to lead upgrading and bulk concentrate recovery. Lead upgrading uses reverse flotation to float off pyrite, which is sent to the final tailings. The by-product is lead concentrate containing 40% lead. In the bulk circuit, combined lead and zinc is floated, producing a concentrate containing 39% zinc and 19% lead. The copper concentrate contains 23.5% copper and the zinc concentrate contains 52.5% zinc. Concentrates are dewatered to 30–40% moisture. Vacuum filters reduce the water content in the zinc, lead and bulk concentrates to around 17%, with further kiln drying to 7% moisture, while the copper concentrate is dried using pressure filters. Production during 2005 was 265,648t of zinc in concentrate, 5,894t of copper in concentrate and 75,417t of lead in concentrate, plus 5.9Moz of silver. TRANSPORT AND MARKETS Copper and zinc concentrates are shipped to worldwide markets as raw concentrates. Lead and bulk concentrates undergo further refining in the company smelter at Belledune. The smelter separates out copper matte, antimony-lead alloys, silver-gold doré and bismuth alloys in successive steps. EXPANSION PROJECTS Recent developments have included the commissioning of a paste backfill plant to simplify the backfilling process underground, and the installation of an SAG mill to give better grinding performance in the preparation of flotation feed. ENVIRONMENT The Brunswick commitment to the wellbeing of communities while sustaining the natural environment is demonstrated by the Daly Point wetland project, the Nepisiquit salmon enhancement project and the company’s environmental awareness programme. Acid mine drainage is now treated in the new high-density sludge treatment (HDST) plant at the No.12 site. A high-density lime (HDL) treatment process is used to reduce the acidity and water content. From : Mining-Technology.com		The surface installations at the Brunswick No.12 mine.
		Three-dimensional image of the No.12 orebody.
		Ore is recovered by blasting then dumping, followed by crushing and finally hoisting to the surface for treatment.
		Oversize rocks in the stopes are drilled and charged using the Weasel remote-controlled rig.
		Using a raiseborer to drill orepasses from one level to the next.
		Shotcrete is used to control the rock surfaces and to provide roof support.
		Water sampling is part of the mine’s continuing environmental protection programme.

Porgera Gold Mine, Papua New Guinea

2007-12-26T17:29:00.000-08:00

The Porgera gold mine is located in Enga Province, about 600km north west of Port Moresby. The mine is operated by a joint venture between Placer Dome (75%), Orogen Minerals Ltd (20%) and Mineral Resources Porgera Pty. Ltd (5%), the latter two representing the state of PNG and local landowners. In early 2006, Barrick Gold Corp acquired Placer Dome in a US$10.4bn takeover, thereby acquiring its interest in Porgera, in which Placer had increased its own holding from 50% during 2002 following its take-over of Aurion Gold Ltd. Porgera was initially an underground operation, with open-pit mining becoming increasingly important from 1993 onwards. Underground production ceased in 1997, but was resumed in 2002. In 2005, 11% of the mine’s output came from underground, with the remainder sourced from open pits and low-grade ore stockpiles. Using an additional secondary crusher and treating higher ore grades, Porgera upped gold output by 20% in 2004, producing 1.02Moz at a cash cost of US$192/oz. However, its output fell again to 835,000oz in 2005, with open-pittable resources nearing depletion. For the remaining life of the mine, production will be obtained from residual underground resources and from stockpiled low-grade ore. GEOLOGY AND RESERVES Mineralisation occurs along the margins of the Porgera intrusive bodies. The Porgera Zone VII orebody is an epithermal style orebody hosted within thermally metamorphosed sediments of the cretaceous. The four precious metal associations are: auriferous pyrite, sphalerite and galena; coarse euhedral auriferous pyrite; fine anhedral auriferous arsenical pyrite; gold and electrum. The majority of gold occurs as submicroscopic gold associated with pyrite. As of December 2004, proven and probable reserves totalled 58.37Mt grading 3.9g/t and containing 7.31Moz of gold, plus measured and indicated mineralisation containing a further 3.16Moz. Exploration by the joint venture continues to identify medium and low grade extensions to the north of the Main Zone. MINING "In 2005, 11% of the mine’s output came from underground, with the remainder sourced from open pits and low-grade ore stockpiles." The open pit has been mined in five stages, with final-stage overburden removal taking place during 2001. Ore is currently mined in the Stage 5 pit, as well as from underground. The open-pit truck and shovel fleet was expanded in 1995, with an O&K RH200 shovel and five Caterpillar 789 trucks. It was again expanded in 1997 to increase production rates from 150,000t/day to 210,000t/day. The mine now handles more than 210,000t/day of ore and waste, with a target supply to the mill of 17,700t/day of ore. Material-handling requirements in 2005 totalled 6Mt of ore and waste. ORE PROCESSING Run-of-mine ore is crushed and ground, free gold is recovered in a gravity circuit and flotation is used to recover a sulphide concentrate. This is then oxidised using autoclaves, producing feed for conventional carbon-in-pulp cyanide leaching to recover the contained gold. Low-grade stockpile and open pit ore are crushed using a gyratory crusher. Coarse ore is conveyed from the stockpile to two parallel SAG mills. The discharge is pumped to three clusters of cyclones in closed circuit with three ball mills. Coarse SAG mill discharge is crushed in two cone crushers and returned to the SAG feed. The slurry is then pumped to the flotation circuit. A Knelson concentrator gravity separation circuit, installed in 1997, has improved recovery of free gold prior to flotation. Flotation concentrates, thickened to 50% solids, form the feed for the oxidation process. Autoclave feed is pumped through three closed stainless steel carbonate reaction tanks in series, the concentrate being mixed with recycled oxidised slurry. The autoclaves operate at 1,725kPa pressure and 197°C, producing feed for the leaching and CIP circuits. Combined leach and CIP recovery is 90–95% of the contained gold. In 1999, a floatation expansion was installed and additional oxygen capacity was added to increase autoclave throughput. GOLD RECOVERY Thickener overflow is percolated upwards through one of two series of five carbon columns, each containing a static bed of 1.5t of activated carbon. Recovery of gold from solution exceeds 99%. The elusion (ion exchange) circuit consists of two pressurised vessels each holding 10t of carbon. Pregnant carbon is eluted using 15 bed volumes of eluant at 140°C and 400kPa pressure. 10t/d of carbon are stripped. During electrowinning, gold and silver metal is precipitated on to steel wool. It is then pressure filtered in a plate and frame press. The resultant 'cake' is smelted in a 1,000kg induction furnace to produce bars of doré bullion averaging 88% gold. From : Mining-Technology.com		The open-pit mine at Pergora. Porgera is located in Enga Province about 600km north west of Port Moresby.
		Cross-section of underground deposits.
		The open-pit truck and shovel fleet was expanded with larger equipment in October 1995 to increase production rates.
		The plant at Pergora. Mineralisation occurs within the Porgera intrusive complex.
		The mill flowsheet. Low-grade stockpile ore and open-pit ore are crushed using a 1,067mm gyratory crusher.

Kaltim Prima Coal Mine, Indonesia

2007-12-26T17:22:00.000-08:00

Kaltim Prima, one of the new generation of Indonesian thermal coal producers, is located in north-eastern Kalimantan. It is operated by PT Kaltim Prima Coal (KPC), which from the project's inception up to late 2003 was jointly owned by BP and Rio Tinto. The Indonesian government receives a royalty equivalent to 13.5% of the revenue. The operation is self-contained and employs some 2,700 people.

Although BP and Rio Tinto's Contract of Work required the companies to divest part of their holding to local interests, up until 2003 no Indonesian purchaser was able to raise the finance needed to buy them out.

"PT Bumi is planning further expansion to 30Mt/yr, plus the development of the Bengalon reserve, some 25km from the existing Sangatta operations."

In mid-2003, the companies announced the sale of their holdings in KPC to PT Bumi Resources for a cash price of $500m, including assumed debt. PT Bumi Resources already owned PT Arutmin Indonesia, another major Indonesian coal producer, and has interests in oil, natural gas and mining, amongst other commercial sectors.

In 2006, PT Bumi announced the sale of all its coal holdings to PT Borneo Lumbung Energi for $3.2bn. However, the deal subsequently failed, although PT Bumi later indicated that it still intends to divest a proportion of its holdings.

PROJECT DEVELOPMENT

BP and CRA (now Rio Tinto) successfully tendered for a 7,900km² licence area in eastern Kalimantan in 1978. Exploration from 1982–86 indicated reserves of 112Mt of export-quality thermal coal. Construction began in 1989 and the mine was commissioned in 1991 as a 7Mt/y operation at a cost of $570m.

The mine has subsequently been expanded, with a sales target of 20Mt/yr by 2005. PT Bumi is planning further expansion to 30Mt/yr, plus the development of the Bengalon reserve, some 25km from the existing Sangatta operations.

In mid-2004, PT Bumi awarded the Australian contractor, Henry Walker Eltin, a $1.2bn, ten-year contract for infrastructure development and mining services at Bengalon, which will have a 6Mt/yr initial capacity.

GEOLOGY AND COAL QUALITY

Pressure and heat associated with an igneous intrusion has increased the rank at Kaltim Prima to high-volatile bituminous coal. A total of 13 seams range in thickness from 1m to 15m; typically in the range of 2.4m to 6.5m. Seam dips vary from 3° to 20° at the outcrop. The seams are very clean in terms of mineral matter and sulphur and, at 4–8% in some areas, the in-situ moisture content is low.

As of the end of 2005, PT Bumi cited reserves at Sangatta at 621Mt, plus 165Mt at Bengalon. The company also has measured and indicated resources of some 3,700Mt.

As of mid-2004, PT Bumi cited reserves at Sangatta at 462Mt, plus 157Mt at Bengalon. The company also has measured and indicated resources of some 2,200Mt.

The operation produces two main export products. Prima Coal is a high-volatile bituminous steam coal with high calorific value, very low ash, low sulphur and low total moisture. Pinang Coal is similar but has a higher moisture content. Quality parameters are:

Product	Prima Coal	Pinang Coal
Moisture (total)	9.5%	14%
Ash	4%	6%
Volatiles	39%	39%
Fixed carbon	52%	46%
Total sulphur	0.5%	0.5%
Heating value (adb)	30.1MJ/kg	27.6MJ/kg
Heating value (gar)	28.5MJ/kg	26.0MJ/kg
adb = air-dried basis gar = gross, as received

KPC blends run-of-mine coal from its various pits to ensure product consistency.

As of end-2001, Kaltim Prima had mineable reserves totalling 462Mt, plus measured and indicated resources of nearly 2,200Mt.

MINING TECHNOLOGY

KPC operates six to 12 individual open pits at any time, the average stripping ratio being 7.5bcm (bank cubic metres) of overburden per tonne of coal. The overburden material degrades quickly on exposure to the atmosphere and generally provides easy digging.

Some overburden rock requires blasting to ensure adequate fragmentation for the shovels. KPC carries out its own mining in most of the pits, but also contracts out a smaller proportion of its mining requirements.

"With selective mining, over 90% of the run-of-mine coal only needs crushing and blending to give export-quality Prima Coal."

The mine's loading fleet consists of over 20 large hydraulic shovels and backhoes with bucket capacities of up to 34m³. Leading suppliers include Hitachi, with nine EX3500 machines and six EX1800s, and Liebherr, which has six R996 Litronic shovels/backhoes on site.

Overburden haulage involves a fleet of 137 trucks, including Caterpillar 785s and 789Bs with capacities of 135–185t, Cat 777s (85t) and Komatsu HD785s (also 85t). Truck scheduling is carried out using a GPS-based Mincom dispatch and management system.

COAL PROCESSING

With selective mining, over 90% of the run-of-mine coal only needs crushing and blending to give export-quality Prima Coal. Coal from the seam roofs and floors contains more mineral material, and so has to be washed. This 'dirty Prima' and Pinang material is handled separately from the 'clean Prima', with individual streams for the different raw materials.

After crushing to –50mm in Gundlach rolls crushers, the washing plant uses dense medium cyclones for 0.5mm to 50mm feed, and spirals for the –0.5mm material, products being dewatered in centrifuges before blending into the Prima Coal stockpile.

OVERLAND TO THE PORT

The mine site contains separate stockpiles for the Prima and Pinang products, holding 60,000t and 35,000t respectively. Coal is reclaimed and transported by a 13km-long, 2,100t/h-capacity overland conveyor to Kaltim Prima’s dedicated port facilities at Tanjung Bara.

Further stockpiles hold a live capacity of 350,000t of Prima and 150,000t of Pinang coals. Coal is transferred directly from mine to ship whenever possible.

Vessels of up to 220,000dwt can be handled by the port, with loading facilities at the end of a 2km-long jetty. Twin quadrant loaders can each handle up to 4,700t/h, the normal loading throughput.

PRODUCTION

Since production began in 1992, Kaltim Prima has increased its output year-on-year, from 7.3Mt in its first year to some 17Mt in 2002 and 2003. PT Bumi is now expanding the Sangatta operation to 30Mt/yr, with a further 6Mt/yr to come from Bengalon.

The operation produced 27.6Mt in 2005, with a target for 2006 of 36Mt of coal and some 700Mt of overburden.

From : Mining - Technology.com

Kaltim Prima is one of the major export coal mines developed in Kalimantan, Indonesia, over the last ten years.

Thick, regular seams make for straightforward mining conditions.

One of the mine’s Hitachi hydraulic excavators, working with Cat hauler.

Kaltim Prima has six Liebherr R996 Litronic excavators, used with Cat 789B haulers for overburden removal.

Five of the mine’s fleet of Caterpillar 789B haulers. Truck scheduling is carried out using a Mincom dispatch and management system, based on a global positioning system (GPS) to locate and track individual vehicle movements.

A luffing and slewing stacker (foreground) and a bucket-wheel stacker-reclaimer (behind) at Kaltim Prima’s port stockpile.

One of the two quadrant shiploaders which together can load bulk carriers of up to 180,000dwt at 4,200t/h.

Cannington Silver and Lead Mine, Queensland, Australia

2007-12-26T17:19:00.000-08:00

he Cannington silver mine is located in north-west Queensland, 200km south east of Mount Isa, near the township of McKinlay. The deposit was discovered by BHP Minerals in 1990 and the mine was commissioned in 1997 at a cost of some AUS$450m. Full production was achieved in early 1999, since when capacity has been expanded from 1.5Mt/y of ore to over 3Mt/y. Cannington is the world's largest single silver producer, representing about 6% of the world's primary silver production, while its lead production represents about 7% of the world's primary lead output. The lead concentrate contains 70% lead and over 3,000g/t silver with low levels of impurities. Long-term contracts for concentrate sales have been agreed with Pasminco (now Zinifex) in Australia, Metaleurop in France, Berzelius in Germany, and various smelters in Japan and Korea Zinc. GEOLOGY AND RESERVES Cannington lies in the south-east corner of the proterozoic Mount Isa Block, within the metamorphics of the lower middle proterozoic eastern succession and overlain by 60m of younger sediments. It is divided by faulting into a shallow, low-grade Northern Zone and a deeper, higher grade Southern Zone. Initial mining will be undertaken in the Southern Zone. Cannington’s major economic sulphides are galena and sphalerite. The silver occurs mainly as freibergite but is also present in solid solution within galena. At the end of 2005, the orebody contained proved sulphide ore reserves of 18.0Mt grading 477g/t silver, 10.7% lead and 3.9% zinc. Measured resources totalled 2.3Mt at 536g/t Ag, 11.94% Pb and 4.49% Zn. The metallurgical recovery rates for zinc, lead and silver were 66%, 88% and 84% respectively. MINING METHOD Cannington is an underground mine accessed via a 5,250m-long, 5.2m-high by 5.5m-wide decline. The main, thicker hanging-wall orebodies of the deposit are mined by transverse, longhole open sloping. "Full production was achieved in early 1999, since when capacity has been expanded from 1.5Mt/y of ore to over 3Mt/y." During the first year of production, a vertical hoisting shaft with a finished internal diameter of 5.6m was constructed from the surface to 650m for ore haulage. The excavation method involves stripping out a 1.8m-diameter raise-drilled pilot hole and lining with concrete from the surface. The shaft is equipped with a tower-mounted friction winder and two 9t skips in counterbalance running on rope guides. The skips are hoisted from a loading station on the 610m level and reach a final hoisting speed of 12m/s. On the surface, tipping scrolls in the shaft headframe tip the skips into a surface bin for transfer to the mill’s stockpile. PROCESSING Processing steps used to produce the lead and zinc concentrates include comminution, flotation, leaching and dewatering. Waste water is pumped to a tailings dam with the flotation overflow. The overflow from the lead concentrate thickener is recycled to the lead flotation circuit. The operation of the concentrator is automated with progammable logic controllers (PLCs), an online sample analyser being used to provide continuous assays on a number of the concentrator streams for silver, lead and zinc. The silver is leached from the lead and zinc concentrates before smelting. PRODUCTION During the year ending June 2006, Cannington mined 3.1Mt of ore grading 461g/t silver, 10.3% lead, and 3.7% zinc. Payable metal production was 38.45Moz of silver, 266,321t of lead and 68,779t of zinc. EXPANSION BHP Billiton has been implementing its Cannington Growth project since 2003, with the aim of improving recoveries, bringing the Northern Zone orebody into production and sustaining ore production at a rate of 2.4Mt/y. TRANSPORT, STORAGE AND EXPORT After dewatering, the lead and zinc concentrates are stored in a 10,000t-capacity storage shed before being loaded into 118t-capacity side-tipping, covered trailer roadtrains by a front-end loader for transport to Cannington's storage and rail loading facilities at Yurbi on the Matilda Highway. Supplied by Roaduser Research, the three 53.5m-long Icon roadtrains carry eight covered bins mounted on six trailers, loading and unloading taking about 20 minutes at each end of the journey. The concentrates are stored separately in an 8,000t-capacity shed at Yurbi prior to loading into rail wagons. Queensland Rail has supplied 50 new 63t-capacity wagons for transporting the concentrates to the port of Townsville for export to world markets. From : Mining- Technology.com		When in full production, Cannington will become the world's largest single silver producer, representing about 6% of the world's primary silver production.
		The Cannington mine is located in north-west Queensland (Australia), 200km south east of Mount Isa, near the township of McKinlay.
		The hoisting shaft head frame. The excavation method involves stripping out a 1.8m-diameter raise drilled pilot hole and installing a concrete lining working down from the surface.
		Boxcut development at the start of the decline back in 1993.
		Processing plan layout schematic. Waste water will be pumped to a tailings dam with the overflow.
		Metroliner landing at Cannington.

Hajar Metal Mine, Morocco

2007-12-26T17:15:00.000-08:00

Located in the Guemassa massif, 35km south of Marrakesh, the polymetallic Hajar deposit was discovered in the 1980s. In 1988, ONA and the state-owned Bureau des Recherches et des Participations Minières (BRPM) formed Compagnie Minière des Guemassa (CMG) as a 70:30 joint venture to undertake development. Mining commenced during 1992. CMG effectively operates as a subsidiary of ONA, a private-sector company that was formed in 1919 as Omnium Nord Africain and has been active in mining since 1928. In 1995, ONA formed Managem to co-ordinate group mining activities, and the CMG site now also houses Managem's cobalt electrowinning and metals derivatives hydrometallurgical operations, as well as R&D facilities for the engineering subsidiary Reminex. The whole site was certified to ISO14001 in January 2004. "The process plant has recently been expanded to 6,000t/d in order to treat Hajar ore blended with material trucked from the company's new Drâa Lasfar mine." DEVELOPMENT AND INVESTMENT The operation was initially designed for a rated capacity of 3,000t/d, processing run-of-mine ore averaging 10.5% zinc, 3% lead, 0.3% copper and 60g/t silver. Overall investment in the start-up project was Dh1,000m ($108m). Thereafter, CMG invested Dh110m to increase capacity from 3,000t/d to 4,200t/d. The process plant has recently been expanded to 6,000t/d in order to treat Hajar ore blended with material trucked from the company's new Drâa Lasfar mine, 15km west of Marrakesh, which started building up to full rate output in 2005. CMG employs approximately 260 people. GEOLOGY AND RESERVES Hajar mines a polymetallic sulphide deposit hosted in upper visean rocks. Hydrothermal mineralisation occurs 120m below surface, in the contact zone between a lower volcano-sedimentary series and an upper sedimentary formation. The upper part of a mineralised lens, comprising banded pyrrhotite, pyrite, blende, galena and chalcopyrite, is relatively copper-rich. During 2005, Managem reported that proven and probable reserves at the Hajar and Drâa Lafar mines had been increased by 1.2Mt and resources by 2.7Mt. Drâa Lasfar will mine an envelope of ore 1m to 25m thick, 525m long and dipping at 70° to 80° to at least 700m depth. Pre-production reserves and resources totalled 7.79Mt grading 5.52% zinc, 2.3% lead and 0.27% copper. During 2005, significant resources were discovered down-dip from the current mine, and feasibility studies commenced. MINING Mechanised trackless mining utilises a ramp for machinery access and air intake, automated ore hoisting in the 500m Shaft No.1, ventilation via Shaft No.2, and 800m³/d backfill delivery from surface via the No.3 and 4 Shafts. The ramp descends to the crushing station and pump room at 450m. The core of the principal orebody has been extracted via three main levels, using sub-level caving (65% of output) and the rill mining cut-and-fill technique (alternate cuts filled with cement/tailings and waste rock backfill). Today, however, mining is concentrated at the edges of this orebody and in smaller subsidiary mineralised areas. Here a modified cut-and-fill technique called M630 accounts for 80% of the output, with rill mining contributing 15% and sub-level caving only 5%. Consequently, total output has tended to decrease and Drâa Lasfar has been developed to compensate for this. "Recovery to previous levels of output is anticipated by 2008–9." Face drilling is done with Atlas Copco RB282 and Tamrock Axera rigs, and longhole drilling with an Atlas Copco Simba H250. Toro and Atlas Copco Wagner LHDs haul to the ore passes. Getman utility vehicles are used for scaling, bolting and loading explosives. The mining rate is up to 4,500t/d (1.5Mt/y). Drâa Lasfar is a cut-and-fill operation, and is equipped with an Atlas Copco drilling, loading and trucking fleet, and Getman service vehicles. ORE PROCESSING Comminution starts underground, where the Nordberg underground jaw crusher produces –120mm feed. On surface, Nordberg HP200 cone crushers supply Allis/Svedala rod and ball mills that feed 10mm material to flotation. Banks totalling 35 Dorr Oliver and Outokumpu conventional mechanical cells sequentially separate lead-silver, copper and zinc concentrates. The zinc concentrate is subsequently heated and passed through Sala magnetic separators. Thickened concentrates are filtered in two stages by Vernay vacuum and Larox pressure filters, reducing moisture to the 10% shipping limit. The subsequent expansions utilise the same process route but with Outokumpu tank cells and Kumera regrind mills. Outokumpu online analysers and a Bailey distributed control system optimise the whole operation. With recovery rates of 75% lead, 70% copper and 94% zinc, Hajar produces concentrates grading of 68% Pb, 28% Cu and 52% Zn, which are delivered by road and rail to the port of Safi for shipment mainly to European customers. PRODUCTION Concentrates production at Hajar has generally declined in recent years as the core area has been worked out and ore grades have decreased. Zinc concentrate production increased 4.5% in 2002 to 172,560t and lead concentrate by 12.3% to 29,890t, although copper-in-concentrate fell 6.9% to 17,799t. Output has seemingly declined since then but costs have been reduced. Recovery to previous levels of output is anticipated by 2008–9. From : Mining- Technology.com		Hajar is located at an elevation of some 800m.
		Outokumpu tank flotation cells.
		One of the mine’s drilling jumbos.
		Outokumpu Electronics Courier 30 online analyser.
		The concentrator control room.
		One of the Larox pressure filters.
		The tailings disposal area has been carefully engineered.

Palabora Copper Mine, South Africa

2007-12-26T17:12:00.000-08:00

Located 360km north east of Pretoria, close to the Kruger National Park, Palabora is South Africa's leading copper producer, and is also a major source of vermiculite and baddeleyite (zirconium oxide). The majority shareholders in Palabora Mining Co. are Rio Tinto plc (57.7%) and Anglo-American. Open-pit mining commenced at Palabora in 1964 and ended in 2002 when the pit reached its final economic depth. The development of an underground mine to work the ore remaining below the pit bottom began during the final years of open-pit production, at a cost of some $465m, with the prospect of a further 20 years' life in the underground operation. The integrated copper-production complex has a metal-refining capacity of 135,000t/y, although the change to underground mining means that some of this capacity is now redundant. The operation employs around 1,800 people. GEOLOGY AND RESERVES Palabora contains magnetite, vermiculite, apatite, zirconium, titanium and uranium as well as copper. The deposit is hosted in an alkaline igneous complex comprising mainly pyroxenite with occurrences of pegmatites, foskorite and carbonatite. Three separate mineralised zones have been identified within the complex’s 20km² surface outcrop, of which the most northerly is phosphate-rich while the central (Loolekop) zone forms the basis for Palabora’s copper production. The copper orebody is hosted in a carbonatite pipe within which grades are typically concentric with the highest values (1.0% copper) at the core. The higher-grade mineralisation extends well beneath the centre of the projected final open-pit floor. The underground mine has been developed on a proven reserve of 225Mt at 0.7% copper, plus an additional probable reserve of 16Mt grading 0.49% copper. By the end of 2005, proven and probable reserves totalled 112Mt grading 0.56% copper, representing a significant reduction from the tonnage and grade cited the year before. Rio Tinto recorded a US$161m asset write-down in its 2005 accounts to reflect this. PRODUCTION During 2006, Palabora treated 10.7Mt of ore grading 0.71% copper, giving an output of 61,500t of copper in concentrates. While production in the early stages of the underground operation had been hampered by problems with fragmentation in the block cave and secondary breaking systems, these seem to have been overcome in the past two-to-three years. The Palabora smelter produced 81,200t of copper metal, compared with 80,300t in 2005. The mine’s output of magnetite and nickel sulphate was 1.13Mt and 120t respectively, with 198,000t of vermiculite. Since it began operations, Palabora has created a stockpile of some 240Mt of magnetite, grading 56% iron and 2.3% titanium dioxide, for which it is began soliciting offers for sale in early 2005. OPEN-PIT MINING Throughout its 35-year life, Palabora was often at the forefront of surface mining technology developments. A key feature was its use of a trolley-assist system for haul trucks coming out of the pit, to save diesel, and it was one of the early users of both in-pit crushing and computerised truck despatching. The open-pit fleet consisted of around 20 Euclid and Unit Rig trucks, with four P&H 2100XPA and 2,800 shovels. Truck payloads were monitored using a Pit Control on-board weighing system on the shovels, linked to the Modular Mining Systems' despatching and monitoring programme. The Fuller-Traylor gyratory in-pit crusher, with a nominal capacity of 5,000t/h, fed the 1.8m-wide main conveyor that carried crushed ore up a drift in the pit wall to the coarse ore stockpiles on surface. UNDERGROUND DEVELOPMENT The underground mine is a block caving operation, the first such system to be used in metal mining in South Africa. With the introduction of the underground operation, the output of ore has fallen from the 82,000t/d achieved in the previous open pit to 30,000t/d. However, the transition to underground production has proved to be problematic, especially in relation to the handling of oversized ore in the drawpoints, and the mine has struggled to meet its production targets. The average output during late 2003 was around 20,000t/d, and additional secondary breaking systems are being installed to help reduce the drawpoint bottleneck. Shaft Sinkers was contracted to install the main service shaft and 1,280m-deep production shaft, while RUC Mining Contracting has been carrying out the underground development. This included driving around 36km of tunnels plus the underground crusher stations, ore handling infrastructure and the undercut level for the first block cave, situated 500m below the final pit bottom. The crushing stations are being fitted with four ThyssenKrupp 900t/h double-toggle jaw crushers that feed a 1.32km conveyor linking to the production shaft. ORE TREATMENT AND SALES Palabora employs one of the most complex recovery circuits installed at any copper mine, producing eight metal, mineral and chemical products in around 20 different varieties and grades. The complex includes a concentrator, copper smelter and refinery, currently capable of producing 135,000t/y of copper plus by-products. Phosphate-rich tailings are delivered to Foskor, while Palabora sells its own copper, precious metals, nickel, zirconium, magnetite and vermiculite on domestic and world markets.		Palabora is situated in north-eastern South Africa, next to the Kruger national park.
		The Palabora open pit. The very competent rock allows the pit walls to be cut much steeper than is normal in open-pit mining.
		Loading in the open pit, the bottom of which is now over 230m below sea level.
		One of the haul trucks fitted with a pantograph for the trolley-assist system, which uses electric power from the main grid to move the trucks up the steep pit ramps.
		The smelter complex at Palabora.
		Copper smelting to produce anodes for subsequent refining to high-purity copper metal.
		Construction of the twin headframes for the underground mine at Palabora.
		Underground development, using a twin-boom jumbo to drill the marked-out

Finsch Diamond Mine, South Africa

2007-12-26T17:08:00.000-08:00

The Finsch diamond mine, located near Lime Acres, 160km northwest of Kimberley, is one of seven operations managed by De Beers Consolidated Mines (DBCM), formed in July 2004 as the wholly owned South African mining subsidiary of Luxembourg-based DB Investments / De Beers SA. This restructuring created a company that can be empowered under the terms of South Africa’s Mineral & Petroleum Resources Development Act. Discovered in 1961 during exploration for asbestos, the deposit was first developed as an open pit. Since 1991, production has come from the underground mine beneath the old pit. Production in 2005 totalled 2.22Mct – 15% of DBCM’s total output – from 5.94Mt of kimberlite ore, giving a recovered grade of 37.3 carats per 100t of ore. Employees numbered 1,319 at the year-end. GEOLOGY Finsch is a classic diamondiferous kimberlite pipe, which has a surface expression of around 17.9ha. The country rocks consist of banded ironstones overlying dolomites and limestones, the pipe itself consisting of weathered kimberlite (yellow ground) to a depth of around 100m with unweathered material (blue ground) beneath. Reserves at Finsch are sufficient to maintain mining at current rates for a further 27 years. MINING The underground mine is accessed via a spiral decline from surface to the 680m level and a 9m-diameter, 763m-deep shaft equipped with three automatic Koepe hoists and capable of handling 5Mt/y of ore. Underground development began in 1978 and the shaft was commissioned in 1982. The upper levels of the underground mine use a sub-level open stoping system. The ore and waste is moved from the production levels via vertical ore passes that feed the material to the crushers. The ore is then transported by belt conveyor to the shaft systems for hoisting to the surface. Production from the open-stope blocks 2 and 3 on the 430m and 510m levels below surface is being replaced by a block-caving system in block 4 on the 630m level that will reach full production of 3.8Mt/y of ore between 2007 and 2011. This will be depleted by 2015, with block 5 beneath following it into production in 2014. Stope development utilises ore passes raise-bored to 2.9m diameter, then opened out to 6m diameter using a sliping rig that fits within the ore pass to drill the full profile. Semi-automated Tamrock drill rigs are used for drilling production rings in the open stopes. Rings consist of 102mm-diameter holes up to 45m long, through a full 360°. Dry drilling is used because of the weathering characteristics of the kimberlite. "In November 2005, Finsch started using an automated ore-transport system underground, costing US$18.5m to install." Finsch makes use of specially developed, repumpable emulsion explosives, blended from components mixed underground and placed using dedicated transport and charging vehicles. The emulsion is sufficiently viscous to be pumped up 102mm vertical holes and to remain in position, and is inert until primed during charging. Benefits of this system include reduced carbon monoxide and nitrogen oxide emissions after blasting, and reduced explosive usage in fewer holes per ring. Detonation is controlled from the blasting cubicle in the underground production centre, with precise timing achieved by individually programmed microchip detonators. 12t-capacity LHDs dump broken ore into Finsch’s eight ore passes, each of which has a capacity of 10,000t. MMD sizers reduce the kimberlite to –300mm for transport to the shafts and hoisting to surface. In November 2005, Finsch started using an automated ore-transport system underground, costing US$18.5m to install. Centred on a specially built, high-speed, high-strength concrete road, 630m below surface, this marked a world first for underground mining in relation to fully automated trucking. COMMUNICATIONS Since 1988, Finsch has used an underground vehicle management and communication system. This was upgraded in 1995 to an El-Equip MultiCom radio-controlled data transfer system based on leaky feeder technology. The system permits multi-channel voice and data transmission. The position of LHDs underground is monitored using Modular Mining Systems’ dispatch system, the controller on surface instructing the individual machines where to load and dump through the mine-wide communications network. DIAMOND RECOVERY Run-of-mine ore is crushed and screened, while –18mm and –3mm material is processed separately. Dense-medium separation is used for the coarser ore, while the fine material is processed through a pan plant and by high-intensity magnetic separation. The concentrates are retreated in cyclones to reduce the volume further, then combined and dried to form the feed for X-ray fluorescence sorting to recover the diamonds. Tailings are passed over grease belts to retain any residual stones. Between February 2005 and end-September 2006, the engineering firm, Bateman, carried out a major upgrade of the technology, also increasing the feed rate to the plant to 900t/h. From : Mining- Technology.com		The open pit at Finsch diamond mine.
		A semi-automated Tamrock production drill rig is used in the drill rigs and blasting areas.
		An LHD in operation. Each has the capacity for 10,000t of material.
		The process and treatment plant.
		The treatment recovery control centre.
		The existing main ventilation fans and the new booster fans will be monitored continuously by PLCs.
		Vehicle dispatch schematic.

Kloof Gold Mine, South Africa

2007-12-26T17:06:00.000-08:00

The Kloof gold mine lies approximately 60km south west of Johannesburg and 20km from Carletonville, on the border of Gauteng and Northwest Provinces, South Africa. Wholly owned by Gold Fields Ltd, it consists of three sections, Kloof, Libanon and Leeudoorn, which were amalgamated into one operating division during 2001–02. The mine operates at depths of 1,000m to 3,500m and employs 14,800 people. Since 1939, when the Venterspost mine came in stream, the Kloof complex has treated nearly 250Mt of ore at an average yield of 9g/t to produce over 71Moz of gold. GEOLOGY AND RESERVES Kloof lies in the 'West Wits' goldfield, part of the Archaean-age Witwatersrand Basin, between the north-trending Witpoortjie Fault to the east and the Bank Fault to the west. The basin itself consists of a 6km thickness of argillaceous and arenaceous sedimentary rocks within the Kaapvaal Craton. Gold mineralisation is found in quartz pebble conglomerate reefs, the gold generally occurring in native form with pyrite and carbon. Kloof is the highest-grade gold mine in South Africa. As of mid-2006, Kloof’s proven and probable ore reserves above the existing mine infrastruture totalled 39.4Mt at 9.7g/t Au, containing 12.3Moz of gold. Below the existing infrastruture (deeper than 3,352m below surface), a further 4.6Mt of probable reserves contain an additional 1.9Moz of gold, giving a total proven and probable reserve at Kloof of 54.2Mt containing nearly 15Moz of gold. MINING Kloof mines the Ventersdorp Contact Reef (VCR) at depths of between 2,500 and 3,700m with minor production from the Kloof (KR), Libanon (LR) and Main (MR) reefs. The three divisions operate five shaft systems. Longwall mining is currently used while appropriate footwall infrastucture is being developed for a change to dip-pillar mining. The Kloof Division sources the VCR and KR and has estimated reserves of 44.1Mt at a life-of-mine (LoM) head-grade of 13.9g/t gold. These are scheduled for depletion by 2021 at an average production rate of 170,000t/month. The Libanon Division sources production from the VCR, KR and MR, with the latter predominating. Access is via seven operating shafts, the ore being transported via a surface rail system to the metallurgical plant at No.3 shaft. Mining is scattered throughout the orebodies to extract pillars and small remnant zones from earlier working. Libanon, parts of which have been in operation since 1934, will be depleted by 2009 at an average production rate of 140,000t/month. Leeudoorn Division mines the VCR and KR via a single shaft using the same methods as the Kloof Division. Its reserves are expected to be depleted by 2009 at an average production rate of 90,000t/month. ORE PROCESSING Each of the Kloof divisions operates its own gold recovery plant – the Kloof (KMP), Libanon (LMP) and Leeudoorn Metallurgical Plants. The KMP and LMP process routes comprise three-stage crushing, two-stage rod and pebble milling closed by hydrocyclones, pulp thickening, air-agitated leaching, drum filtration, zinc precipitation and smelting to doré. The crushing plant includes a facility for manual waste sorting. The plant capacity is 160,000t/month and up to 180,000t/month without waste sorting. Goldfields is carrying out a feasibility study into converting the Kloof plant from conventional crushing and grinding to semi-autogenous grinding (SAG-milling). The LMP plant mills in cyanide resulting in cyanide-bearing plant solutions requiring strict water controls. The design capacity of LMP is 145,000t/month. The Leeudoorn Plant receives run-of-mine ore that is crushed and sent to a stacker-reclaim system where the ore is blended prior to reclamation and delivery to the milling circuits. The mills at Leeudoorn are equipped with variable-speed ring motor drives and can be operated as autogenous or SAG mills. Milled ore is leached in air-agitated tanks and treated by carbon-in-pulp prior to elution using Anglo American’s AARL process. Gold is recovered from the eluted solution by electrowinning before smelting to doré. PRODUCTION AND COSTS During the 2005–06 financial year, Kloof produced 914,000oz of gold, 12% lower than in 2004–05, largely for geological reasons in relation to the Ventersdorp Contact Reef. These meant that larger amounts of lower-grade ore had to be mined, thereby reducing the overall yield for the year from underground ore from 9.1g/t to 8.7g/t. In all, the mine processed 3.67Mt of ore at an average yield of 7.8g/t gold, comprising 3.21Mt of ore from underground and 460,000t of low-grade surface material. Total cash costs of production rose from US$379/oz in 2004–to S$412/oz in 2005– with a total production cost of US$467/oz. THE FUTURE Gold Fields has been carrying out a feasibility study into the development of a tertiary decline infrastructure to access the Kloof Extension Area (KEA), which targets a 2Moz Ventersdorp Contact Reef resource below the current mine infrastruture. The company has also been re-evaluating the potential of the mine’s Eastern Boundary Area in view of the current high gold price, which has enhanced the viability of previously un-economic resource areas. Gold Fields is also looking at operating synergies between Kloof and the neighbouring South Deep mine, which it recently bought from the previous owners, Barrick Gold Corp. and Western Areas Ltd. With joint deep-level surveys already having been completed, there is significant potential for optimising both mines through greater operational integration.		The Kloof gold mine lies approximately 60km southwest of Johannesburg and 20km from Carletonville, in Mpumalanga province, South Africa. Wholly owned by Goldfields Ltd, it consists of three divisions: Kloof, Libanon and Leeudoorn.
		The main shaft complex at Leeudoorn. The three divisions operate six shaft systems and currently include three shaft-sinking operations.
		The Libanon mine complex comprises worker accommodation as well as the No.4 shaft (behind) and concentrator (right).
		The No.4 shaft at Kloof with the mine’s main shaft in the background.

Venetia Diamond Mine, South Africa

2007-12-26T17:05:00.000-08:00

The Venetia diamond mine, which opened in 1992, is De Beers Consolidated Mines' flagship operation. Situated 80km from Musina (formerly Messina) in Limpopo Province, and involving an investment of R1.1bn ($400m), the mine is South Africa’s largest diamond producer, with an output of 8.52Mct from 5.93Mt of ore in 2005 at a recovered grade of 143.5ct per 100t of ore, a substantial improvement on the 122.4ct per 100t of ore achieved in 2004. It employs 955 people. Venetia has been operated by De Beers with The Saturn Partnership, in which Avmin (formerly Anglovaal) had an 87.5% holding, having a 50% profits interest. Avmin sold this interest to De Beers for $590m in 2000, together with its 8% profits interest in the Finsch mine, with De Beers seeking to buy out the remaining Saturn holding to give the company full ownership over Venetia. De Beers Consolidated Mines was formed in 2004 as a black economic empowerment vehicle for the group within South Africa. It is a 100% subsidiary of Luxembourg-based DB Investments/De Beers SA. Venetia was the first diamond mine to achieve ISO 9002 quality management certification. DEVELOPMENT Diamond-bearing gravels were discovered as early as 1903 close to the Limpopo River, 35km north east of the present mine. In 1969, De Beers launched a reconnaissance sampling programme to locate the source of these alluvials. Viable kimberlite pipes were discovered in 1980, construction of the mine began in 1990 and full output was achieved in 1993. GEOLOGY There are twelve known kimberlites form the Venetia cluster. Of the eleven pipes and one dyke system, only two of the kimberlites, K1 and K2, are currently being mined. Some of the pipes were formed in multiple intrusive events, which have resulted in a variety of kimberlite types being encountered during mining operations. The kimberlites are clustered over approximately 3km² while the total surface area of the kimberlites themselves is 28ha. OPEN-PIT MINING "Venetia was the first diamond mine to achieve ISO 9002 quality management certification." Venetia is a conventional open-pit mine. Surface mining is expected to carry on for some 20 years and, as the mine becomes deeper, the feasibility of underground operations will be investigated. The current targeted pit floor level is at a depth of 400m. A re-evaluation of the pit design undertaken during 1998 reduced the waste-stripping requirements but Venetia plans to increase waste removal over the next three years from 42Mt to 70Mt in order to create jobs. After waste stripping to expose the kimberlite, the ore is blasted and loaded into trucks, hauled to a crusher (which the engineering firm Bateman is currently replacing), reduced in size and conveyed to a primary stockpile. Crushed ore is then conveyed to the main treatment plant for processing. Key equipment in the pit includes P&H and Reedrill rotary drills and O&K RH200E electric-powered hydraulic excavators, the latter being equipped for monitoring and service purposes by direct radio link to O&K's plant in Germany. Loading and haulage is supervised via a GPS fleet management system. Ancillary equipment includes Bell articulated water bowsers, used for road spraying, vehicle washing and fire-fighting duties. DIAMOND RECOVERY Inside the treatment plant, the kimberlite is further crushed, washed and screened into different size fractions. Dense-medium separation is used to produce a diamondiferous concentrate, which is then subject to X-ray fluorescence sorting to separate diamonds from residual waste. After drying, final hand-sorting recovers the diamonds, which are sent to the offices of the Central Selling Organisation (CSO) in Kimberley for classification into some 5,000 categories based on combinations of size, shape, colour and quality. The recovery plant includes widespread use of Bateman pneumatic conveying systems for handling concentrates, tailings and products. General spillage is handled by a vacuum clean-up system servicing most of the plant equipment. Consisting of a 2,500m-long pipe network, this has over 700 pick-up/collection points, using a mobile vacuum unit to pick up spillage up to 50mm in size. ENVIRONMENTAL Venetia is located in an environmentally sensitive area and De Beers spent some R17m on initial environmental engineering projects. The 35km-long water supply pipeline and other service supply pipelines are buried, the mine has a state-of-the-art dust control system, and noise and lighting impacts are minimised. The company also established the 36,000ha Venetia Limpopo Nature Reserve adjacent to the mine and recently moved a large number of animals from a new mining area to the reserve.		Drilling at night in the open pit. Venetia is situated near Messina in South Africa's Northern Province.
		The plant at dusk. Venetia is the first diamond mine to achieve certification of the internationally recognised quality management system, ISO 9002.
		Lights have been placed strategically and kept to a minimum to prevent disturbances to game.
		After the surrounding earth and rock have been removed to expose the kimberlite, the ore is blasted and loaded into trucks.
		Inside the treatment plant, the kimberlite is further crushed, washed and screened into different sizes.
		The Venetia Process Plant incorporating Bateman machinery. Diamond mining and recovery is a clean operation. Processing of the ore uses no toxic chemicals and produces no chemical pollutants.

CBG Bauxite (Aluminium Ore) Mining Operations, Guinea

2007-12-26T16:00:00.000-08:00

The largest single producer of bauxite (aluminium ore) in the world, Cie des Bauxites de Guinée's (CBG) operations are located in the west of Guinea, close to the border with Guinea-Bissau. Since opening in 1973, the operations produced over 260Mt of bauxite for export. CBG was established in the early 1970s as a 49:51% joint venture between the Guinean government and the Halco partnership, originally comprising a group of international aluminium industry participants. Since 2004, Alcoa and Alcan have each had a 45% stake in Halco, having gradually bought out most of the other founder members. In mid-1999, the government invited Alcoa to take over management of the project. "The operation is facing reducing ore grades as high-grade material is mined out." The operations consist of the Kamsar bauxite treatment plant on the West African coast, and a group of open pit mines located 100km inland, centred on the community of Sangarédi. Mine production rose from 12.2Mt in 2001 to just over 14Mt in 2005, with 11.5Mt/y to 12.5Mt/y of bauxite products being shipped from Kamsar. The operation is facing reducing ore grades as high-grade material is mined out. In 2005, Halco reached agreement with the Guinean government over the development of a 1.5Mt/y alumina refinery at Kamsar, Alcoa and Alcan having already carried out a feasibility study into the project. Commissioning is scheduled for 2009, with a price tag of at least US$1bn. Its capacity could also be trebled by 2019. GEOLOGY AND RESERVES Bauxite deposits are found across much of western and central Guinea, having been formed by the tropical weathering of underlying, aluminium-rich rocks. The deposits are typically close to the surface. Proven reserves total some 2,300Mt with additional probable reserves of 18,600Mt, most of which contains between 40% and 50% aluminium oxide (Al2O3). CBG's operations are currently based on three main ore zones – Sangarédi, Bidikoum and Silidara, with further resources at the N'danga, Boundou Waade and Paravi deposits. Each deposit contains several different types of ore, varying in both grade and physical properties. Its existing resource totals over 300Mt grading 51% Al2O3, sufficient to support production at current rates for at least 25 years. Historically, grades in Sangarédi have been 56–58% Al2O3, while ore in Bidikoum averages 50% and Silidara 52%. In 2006, CBG signed an agreement with the Guinean government and Global Alumina over granting Global Alumina access to some of the CBG bauxite reserve areas. In return, CBG will have future access to some 2,000Mt of bauxite resource that lie outwith its current concession. OPEN PIT MINING While Sangarédi was the orebody on which CBG's operations were founded, today between 85% and 90% of its output of raw bauxite comes from the Bidikoum and Silidara pits. After stripping any thin overburden, the ore is blasted and then loaded using hydraulic excavators into haul trucks for transport to the mine stockpiles. Bench heights of up to 8m allow most of the ore to be mined in one horizontal pass. The mining fleet consists of Demag H185 excavators, Caterpillar 992C and 992D wheel loaders, and 17 Caterpillar 777B and 777D trucks. Run-of-mine ore is stockpiled in long piles that run parallel to the mine's rail sidings, with material from the different pits being tipped in layers to give a consistent blend. The stockpiles are then reclaimed using Caterpillar 992s that dump directly into rail wagons alongside. "Alcoa has made substantial investments in the rehabilitation of the Kamsar plant, including new belt conveyors and dust-control systems." About two hours is needed to load each 100-wagon train, each car carrying around 82t of bauxite. Five or six trains carry ore from the mine to Kamsar each day. BAUXITE PROCESSING Treatment of the run-of-mine bauxite consists mainly of crushing and drying before shipment. Ore wagons are tipped individually, the material being crushed to –100mm before stockpiling. After reclaim using bucket-wheel stacker-reclaimers, the ore is dried from an average 12.5% moisture to 6.7% for shipping. Dried ore is held in a 150,000t-capacity covered stockpile, and is then reclaimed for transport along the plant's 1.6km jetty to the shiploaders. The jetty can handle Panamax-sized vessels of up to 60,000dwt, with around 230 such shipments of metallurgical-grade bauxite scheduled per year. In addition, CBG exports low monohydrate and small amounts of calcined bauxite, and has to import all its fuel and equipment spares through its own port facilities. Alcoa has made substantial investments in the rehabilitation of the Kamsar plant, including new belt conveyors and dust-control systems, with the aim of increasing its export capacity to 13.5Mt/y of bauxite products.		CBG’s operations are centred on the town of Boké, 150km north west of Guinea’s capital, Conakry.
		Exploration drilling at Bidikoum. CBG is continuing its exploration programmes, both in its existing pits and elsewhere on its lease areas.
		One of the mine’s Demag H185 hydraulic excavators, two of which are in face shovels and two, like this, as backhoes.
		CBG has a programme of fitting ‘greedy boards’ to its older Cat 777B trucks to increase their capacity to that of the 777Ds.
		The wagon tip at Kamsar, where a new control system has reduced the tip time per car from four to three minutes.
		One of three drying kilns, used to reduce the moisture content of the bauxite to 6.7% for shipping.
		A Panamax-sized ship offshore the loading jetty at Kamsar.

Benguérir Phosphates Mine, Morocco

2007-12-25T20:48:00.000-08:00

Located 70km north of Marrakesh, Benguérir is the newest of Morocco’s four phosphate mining centres, having started production in 1979–80. Operated by Office Chérifien des Phosphates (OCP), the opencast mine works 24h/d in three shifts and is managed together with the Youssoufia mining and treatment centre. OCP employs around 775 people at Benguérir.

OCP, a state-owned agency formed in 1920, is solely responsible for the Benguérir, Khouribga and Youssoufia mines in central Morocco. The Oued Eddahab deposits in Western Sahara are worked by Phosboucraa, in which OCP acquired a majority interest during 1975.

OCP moved into downstream processing in 1965, converting lower-grade rock to phosphoric acid and fertilisers at its plants at the coastal town of Safi. In 1975, Maroc Phosphore was established as a 100% subsidiary of Groupe OCP, primarily to add value to more rock and to export intermediate phosphate products. The first complex was built at that time.

A second – Maroc Phosphore II – was commissioned in 1981 and a number of joint venture operations since have been established with foreign fertiliser manufacturers, the most recent project involving the Brazilian company, Bunge.

GEOLOGY AND RESERVES

Morocco’s enormous measured phosphorite resources of 85,000Mt are hosted in upper cretaceous, palaeocene and eocene sediments. Sequences comprising clays, marls, limestones and cherts contain several phosphate-rich beds. Benguérir exploits the north-central section, and Youssoufia the western part of the Ganntour reserves (31,000Mt).

Phosphate-rich beds C5 and C6 have been worked near surface while beds C1 to C6 can be worked down dip. Mineable phosphate-rich beds range from 1m to 3m in thickness and grade 22% to 28% P2O5.

MINING

In the first phase of operations (1980–94), up to 3.1Mt/y was mined from the C5 and C6 beds in the near-surface western area. Phase 2 (1994–2018) has continued at the same rate, but is now planned to rise to 4.5Mt/y as beds C1 to C4 are accessed down-dip. The strip ratio currently averages 3.5:1.

Six benches of overburden and phosphate are drilled with rotary blasthole drills and blasted. The waste is stripped by draglines, which dump the rock in the already mined out void and the phosphate loaded by electric shovel or wheel-loader into trucks for haulage to the primary crusher.

The current equipment fleet comprises: two Marion 7500 walking draglines, two P&H 2355 crawler draglines, two Bucyrus-Erie 200B draglines and two B-E 155 electric shovels, two Caterpillar 992C wheeled loaders, six blasthole drills, 22 dump trucks (from 75t to 150t capacity), 24 bulldozers, three graders and three water spray trucks.

OCP acquired the P&H draglines, two Cat and two Komatsu large dozers and four 136t Komatsu haul trucks have been bought for Phase 2.

ORE PROCESSING

Only simple treatment is undertaken at Benguérir. Feeders remove chert and flint ahead of a Krupp primary jaw crusher, which discharges to open storage. A reclaimer supplies a Koch screening plant, which separates plus-10mm waste and supplies minus-10mm wet product at 1,000t/hr by conveyor to the 800,000t-capacity storage/reclaim system.

Moist screened rock is mainly railed 167km to the chemical complex at Safi on the Atlantic coast, with the balance going first to Youssoufia for blending and processing there and thence to Safi.

Here, Benguérir rock is mainly used as feed for the Maroc Phosphore II facility, which incorporates four FCB rock washing lines and three 160,000t/y phosphoric acid plants.

PRODUCTION

Moist screened rock output at Benguérir in 2006 was 3.1Mt, while total OCP phosphate rock exports were 21.63Mt.

From : Mining- Technology.com

Assmang Manganese Mines, South Africa

2007-12-25T20:02:00.000-08:00

The Kalahari Manganese Field, located in Northern Cape Province, about 700km southwest of Johannesburg, contains perhaps 80% of the world's known high-grade manganese ore reserves. The district yields about 4Mt/y, mined mainly by Samancor and Assmang.

Originally established in 1935 and now jointly owned and managed by African Rainbow Minerals and Assore, Assmang wholly owns two mines near the community of Black Rock. The company also produces manganese alloys at its Cato Ridge works in KwaZulu Natal.

"In the future, the company would like to build a new manganese-alloy plant near the mine."

Assmang commissioned Nchwaning in 1972 while the Gloria mine, to the south, started production in 1978. Each had a plant nominally rated to treat 1Mt/y ore.

Early in 2000, Assmang announced an expansion involving the development of a new shaft complex at Nchwaning to add about 2Mt/y of run-of-mine ore capacity, to make Nchwaning the world’s lowest-cost underground manganese mine, and to extend its lifetime by about 30 years.

The expansion, including additional treatment capacity, was commissioned in May 2004 and was completed in May 2005 at a capitalised cost of R780m. In the future, the company would like to build a new manganese-alloy plant near the mine. Assmang works three eight-hour shifts per day from Monday to Friday, as well as a single shift on Saturday, employing a total of 2,510 people at its various operations.

GEOLOGY AND RESERVES

The Kalahari Manganese Field lies within a large structural basin that extends approximately 40km south to north and 5km to 15km east to west, dipping gently northwest. At Black Rock, near the northern end of the basin, the Transvaal System rocks lie about 300m from surface, beneath Kalahari Formation sands and calcretes, Karroo System tillites and Waterberg System shales and quartzites.

The sub-horizontal stratabound manganese ore horizons occur in banded ironstone of the Voëlwater Formation at the top of a sequence of Transvaal System rocks. As well as being faulted, the horizons are folded.

The ore is massive and averages 48% manganese; at Nchwaning it is particularly low in phosphorus while Gloria has a higher manganese-to-iron ratio. At the end of 2006 Assmang's reserves totalled 192Mt with mineral resources of 428.4Mt.

MINING

Both mines are underground operations, using the room-and-pillar method. Nchwaning started with one vertical hoisting shaft, with the 450m-deep No.2 vertical skip shaft added and the plant upgraded in 1981. Gloria combined a vertical shaft for personnel and materials hoisting with a long incline shaft for vehicle access and conveyor hoisting

of the ore to a surface crushing, screening and washing plant.

The new expansion follows this design, having a 2,200m-long incline shaft and the 500m-deep Nchwaning No.3 personnel shaft. There is also a new ventilation shaft, and a workshop located on the 400 level.

Bolted development entries access rooms that are 7m to 8m wide and 3.2m to 3.5m high, while the pillars are normally 8m x 8m. Low-grade ore is left to form both the floor and roof of the rooms.

"Assmang produced about 2.5Mt of manganese ore in the 2006 financial year, not including sales to Cato Ridge."

The established areas use Boart Longyear hydraulic drilling rigs and Wagner Load-Haul-Dump (LHD) machines and trucks to transport the ore to storage silos, primary crushers and screens that feed the hoisting systems. Roofs are scaled using a modified three-wheeled loader.

For the new area, Assmang requested a three-boom rig fitted with two rock drills for face work plus one for roof-bolting, so the mine can drill holes for roof bolts and face-blast holes from the same set-up. Atlas Copco has supplied four purpose-designed Rocket Boomer M3D rigs.

Assmang also added to its fleet of Atlas Copco Wagner LHDs but opted for an alternative truck brand, ordering three Caterpillar AD 30 machines.

PROCESSING AND PRODUCTION

The run-of-mine ore is crushed, washed and screened, with no other processing needed. After the ore has passed through the plants, it is stacked according to size and grade. The capacities of the stacks vary between 280t and 320t each, and are numbered and sampled.

In total, Assmang produced about 2.5Mt of manganese ore in the 2006 financial year, not

including sales to Cato Ridge. Exports travel by the main South African Railways route to Port Elizabeth on the Indian Ocean. Lesser tonnages are directed to the domestic steel industry.

From : Mining- Technology.com

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