The Carajás Mine is the world's largest iron ore mine and is located in the state of Para in Northern Brazil.
Fully owned by Brazilian miner Vale (CVRD), the mine holds over 1.5 billion tons of iron ore in reserves.
The Carajas region boasts the richest reserves and concentrations of iron ore anywhere in the world and was discovered entirely by accident in the late 60s when a US Steel Helicopter was forced to land on a hill in the area to refuel. Surveyors on board noted the baron state of the hill and subsequently discovered that the iron content was as high as 66%.
Other mineral deposits were discovered later; Carajás is rich not only in iron ore but also ores for manganese, copper, tin, aluminium and even gold.
US Steel wanted to develop the Carajás iron deposit but the Brazilian Government was unwilling to hand control over to a foreign company. Brazil is currently the world's largest exporter of iron ore with annual production of over 200Mt.
In 1970 the Brazilian government opted instead to create a joint venture company, Amazonias Mineração SA (AMZA), of which 51% was owned by Vale and 49% was
US Steel subsequently withdrew from the joint venture in 1977 by selling its share to CVRD for $55m. Vale produced a record 296 million metric tons of iron ore at the Carajas Mine for 2007, a 12% rise on 2006. Vale is expected to announce in 2008 the results of a tender for the expansion of the Carajas mine. The $2.48bn project, "Carajas 130," will add 30 million tons a year to the current capacity of 100 million tons a year, the company says.
Geology and reserves
The Carajás ores are found within Archaean iron formations. The volcanic sequence has been weathered to a depth of between 100m and 150m, while oxidation is observed to a depth of up to 500m in the BIFs of the ore zone.
The upper 80% of the reserve comprises a soft, friable enriched limonite near surface passing down into hematite to a vertical depth of around 300m. Hematite rich, but harder and more siliceous pods occur within the soft hematite, but also as a transition to the un-enriched BIF at depth.
The Carajás District contains known reserves of the order of 18 billion tons with an average grade of 65.4% Fe. The reserves are distributed in a number of deposit groups, the largest of which is the North Range with - 6,200Mt @ 65.8% Fe, 0.038% P, 1.0% SiO2, 1.05% Al2O3, 0.45% Mn, 0.01% S, 0.02% KO, 0.03% Na2O and 1.88% LOI. The other reserves include: South Range, 35km to the south – 10,400Mt @ 66.3% Fe; East Ridge – 400Mt @ 65.9% Fe; and South Felix Ridge – 600Mt @ 62.8% Fe. The current production contains < 1% Al2O3, < 1% SiO2, < 0.03% P2O5 and < 0.3Mn, with about 10% lump and 90% fines.
Monday, May 11, 2009
Blue Ridge PGE Project, South Africa
Ridge Mining's Blue Ridge project is situated on the Blaauwbank farm, about 30km south-east of Groblersdal, on the eastern limb of the Bushveld Igneous Complex (BIC), South Africa.
Ridge Mining started exploration work on the project in 2001 and completed a feasibility study at the end of 2005. Mine development, estimated to cost $170m, began in January 2007.
The project is a 50:50 joint venture between Ridge Mining and BEE partner Imbani, which had invested more than $100m of equity by December 2008. In December 2007, project finance agreements were signed with a consortium of banks consisting of the Development Bank of Southern Africa, the Industrial Development Corporation of South Africa, Standard Bank and Investec Bank for R715m, giving full finance through to first production, which is set for the end of 2008.
The cash operating cost assumption for Blue Ridge is $660/oz to produce platinum, palladium, rhodium and gold, giving an expected payback period of five years.
The eastern limb of the BIC, like the rest of the complex, consists of distinct rock strata, including three PGE-bearing layers known as reefs, with one being the UG2 chromitite reef.
The PGEs in the UG2 chromitite occur primarily in discrete mineral phases, varying from sulphide assemblages (predominantly cooperite, braggite, malanite and laurite) to those consisting of a significant component of alloys (such as Pt-Fe alloy) or various telluride, bismuthinide, bismuthotelluride, arsenide and sulpharsenide phases.
Resources
Total Measured, Indicated and Inferred resources are put at 89.9Mt, which includes 38.7Mt of Indicated resources from the neighbouring Millennium area, acquired by Ridge in March 2008, giving a contained 4PGE figure of 9.2Moz at an average grade of 3.2g/t. Total Proved and Probable reserves are nearly 22Mt to give a contained 4PGE figure of nearly 2.3Moz at 3.3g/t.
Production
The mine development is based on two decline shafts; a 700m-long belt decline, which will be used for transporting ore, and an 850m-long truck decline. During 2008 work focused on opening up production levels and faces in readiness for mining to begin in earnest. The plan is to mine only the higher grade portion of the reef, using a method called "Efficient Cut".
Before the plant was commissioned, Ridge Mining stockpiled more than 200,000t of ore – about two months’ worth of throughput for the plant in full production – allowing enough ore to be processed through the concentrator plant while the underground workings continue the ramp-up to full capacity, which is planned for the middle of 2009.
Annually the mine is forecast to produce about 75,000oz of platinum, 35,000oz of palladium, 22,000oz of ruthenium, 13,000oz of rhodium, 2,500oz of iridium and 1,500oz of gold over its initial 18-year life.
Processing
The ore will be processed using crushing, milling and flotation, then milling and flotation again to produce a concentrate. The ore will be fed through a primary ball mill and into primary roughers and cleaners, from where some of the feed will go to a care thickener and the rest to a secondary ball mill and roughers and cleaners, then on to tails thickeners. The concentrator plant is next to the entrance to the main decline shaft, which has a conveyor belt to bring the ore to the surface. Processing testwork show recoveries into concentrate of 82%-86%.
Ridge Mining started exploration work on the project in 2001 and completed a feasibility study at the end of 2005. Mine development, estimated to cost $170m, began in January 2007.
The project is a 50:50 joint venture between Ridge Mining and BEE partner Imbani, which had invested more than $100m of equity by December 2008. In December 2007, project finance agreements were signed with a consortium of banks consisting of the Development Bank of Southern Africa, the Industrial Development Corporation of South Africa, Standard Bank and Investec Bank for R715m, giving full finance through to first production, which is set for the end of 2008.
The cash operating cost assumption for Blue Ridge is $660/oz to produce platinum, palladium, rhodium and gold, giving an expected payback period of five years.
The eastern limb of the BIC, like the rest of the complex, consists of distinct rock strata, including three PGE-bearing layers known as reefs, with one being the UG2 chromitite reef.
The PGEs in the UG2 chromitite occur primarily in discrete mineral phases, varying from sulphide assemblages (predominantly cooperite, braggite, malanite and laurite) to those consisting of a significant component of alloys (such as Pt-Fe alloy) or various telluride, bismuthinide, bismuthotelluride, arsenide and sulpharsenide phases.
Resources
Total Measured, Indicated and Inferred resources are put at 89.9Mt, which includes 38.7Mt of Indicated resources from the neighbouring Millennium area, acquired by Ridge in March 2008, giving a contained 4PGE figure of 9.2Moz at an average grade of 3.2g/t. Total Proved and Probable reserves are nearly 22Mt to give a contained 4PGE figure of nearly 2.3Moz at 3.3g/t.
Production
The mine development is based on two decline shafts; a 700m-long belt decline, which will be used for transporting ore, and an 850m-long truck decline. During 2008 work focused on opening up production levels and faces in readiness for mining to begin in earnest. The plan is to mine only the higher grade portion of the reef, using a method called "Efficient Cut".
Before the plant was commissioned, Ridge Mining stockpiled more than 200,000t of ore – about two months’ worth of throughput for the plant in full production – allowing enough ore to be processed through the concentrator plant while the underground workings continue the ramp-up to full capacity, which is planned for the middle of 2009.
Annually the mine is forecast to produce about 75,000oz of platinum, 35,000oz of palladium, 22,000oz of ruthenium, 13,000oz of rhodium, 2,500oz of iridium and 1,500oz of gold over its initial 18-year life.
Processing
The ore will be processed using crushing, milling and flotation, then milling and flotation again to produce a concentrate. The ore will be fed through a primary ball mill and into primary roughers and cleaners, from where some of the feed will go to a care thickener and the rest to a secondary ball mill and roughers and cleaners, then on to tails thickeners. The concentrator plant is next to the entrance to the main decline shaft, which has a conveyor belt to bring the ore to the surface. Processing testwork show recoveries into concentrate of 82%-86%.
Black Thunder Coal Mine, WY, USA
The Black Thunder thermal coal mine, located in the Southern Powder River Basin of Wyoming, opened in 1977 and for many years was the largest single coal operation in the US. Having been relegated to second-largest, after Peabody's North Antelope-Rochelle operation, also in the Powder River Basin, in 2004 Black Thunder once again became the nation's leading coal-producer following Arch Coal's acquisition of the neighbouring North Rochelle mine from Triton Coal Co. The combined operation is now producing coal at a rate of around 91Mt/y, equivalent to about 10% of total US coal production. In 2004, Black Thunder became the first coal mine in the US to ship a cumulative 1,000Mst (907Mt) over its 27-year life to date.
Construction began at Black Thunder in 1976 with the installation of crushing, conveying, sampling and high-speed train-loading systems. Today, all plant processes are computer controlled, including the precision loadout systems and the hi-tech, near-pit crushing and conveying system installed in 1989.
Until 1998, Black Thunder was owned and operated by ARCO Coal, part of the Atlantic Richfield group. It is now owned by Arch Coal, the second-largest coal miner in the US, which bought the property following ARCO's withdrawal from the coal market.
GEOLOGY AND RESERVES
Black Thunder works coal reserves in the Wyodak seam. Hosted in the palaeocene Fort Union formation, which covers vast areas of Wyoming, Montana and the Dakotas, the seam at Black Thunder is gently dipping, 22m thick and locally splits into the Anderson and Canyon beds separated by up to 18m of waste. In 2004, Arch successfully bid $611m for the rights to mine the neighbouring Little Thunder reserves, which contain some 650Mt of recoverable coal, increasing the property’s reserves to 1,370Mt-plus.
COAL QUALITY
The mine produces low-sulphur, sub-bituminous coal suitable for power station fuel without any preparation except crushing. Black Thunder coal has a heating value of 20.3MJ/kg, and the ash contents are around 5% while as-received moisture is 25–30%. The moisture content of some Powder River Basin coals increases their reactivity to the extent that spontaneous combustion can be a problem if they are not properly handled.
Construction began at Black Thunder in 1976 with the installation of crushing, conveying, sampling and high-speed train-loading systems. Today, all plant processes are computer controlled, including the precision loadout systems and the hi-tech, near-pit crushing and conveying system installed in 1989.
Until 1998, Black Thunder was owned and operated by ARCO Coal, part of the Atlantic Richfield group. It is now owned by Arch Coal, the second-largest coal miner in the US, which bought the property following ARCO's withdrawal from the coal market.
GEOLOGY AND RESERVES
Black Thunder works coal reserves in the Wyodak seam. Hosted in the palaeocene Fort Union formation, which covers vast areas of Wyoming, Montana and the Dakotas, the seam at Black Thunder is gently dipping, 22m thick and locally splits into the Anderson and Canyon beds separated by up to 18m of waste. In 2004, Arch successfully bid $611m for the rights to mine the neighbouring Little Thunder reserves, which contain some 650Mt of recoverable coal, increasing the property’s reserves to 1,370Mt-plus.
COAL QUALITY
The mine produces low-sulphur, sub-bituminous coal suitable for power station fuel without any preparation except crushing. Black Thunder coal has a heating value of 20.3MJ/kg, and the ash contents are around 5% while as-received moisture is 25–30%. The moisture content of some Powder River Basin coals increases their reactivity to the extent that spontaneous combustion can be a problem if they are not properly handled.
Bingham Canyon Copper Mine, UT, USA
Located near Salt Lake City, Utah, US, Bingham Canyon celebrated its 100th anniversary in June 2003. The Bingham Canyon mine, Copperton concentrator and Garfield smelter comprise one of the largest and most up-to-date integrated copper operations in the world: major investments during the past 15 years have ensured economically and environmentally sound operation. Cumulative copper output is now about 17Mt, more than any other mine.
For much of its life, Bingham Canyon was owned by Kennecott Copper Corp. However, during the post-1973 oil crisis shake-out, the company was acquired by British Petroleum, then sold on to Rio Tinto, which operates Bingham Canyon through its 100% subsidiary, Kennecott Utah Copper Corp. The facilities employ about 1,400 people.
In early 2005, Rio Tinto committed $170m to the East 1 pushback project, which will extend the life of the open pit at Bingham Canyon until 2017.
Following research from analysts and investors, Rio revealed in 2008 it was studying deepening the 1.2km pit to shore up an extra 2.83 million tonnes of copper resources.
If this came into fruition, the additional contained copper resources could extend the mine's life from 2019 to 2036, with plans for a subsequent underground mine extending its life even further.
Rio hopes to begin the project in 2009, which is estimated to produce copper valuing about $22.67bn at current prices.
GEOLOGY AND RESERVES
The classic copper porphyry orebody is not only huge but also enjoys a fairly uniform distribution of sulphide mineralisation, mainly chalcopyrite. The existing pit will be worked out by 2013, but open pit and then underground mining will continue after that. As of end-2005, proven and probable open-pit reserves totalled 667Mt grading 0.54% copper, 0.043% molybdenum, 0.32g/t gold and 2.59g/t silver. Total open-pit and underground mineral resources were 960Mt at 0.7% copper, 0.3g/t gold, 0.03% moly and 3.1g/t silver.
OPEN-PIT MINING
The Bingham Canyon pit is now 4km across and very deep. Mining uses a rotary drilling/blasting – shovel/truck – in-pit crushing system, with two to four blasts per day. To contain costs, management has been quick to utilise the most cost-effective drilling, loading and haulage equipment and management tools available.
One of the first of the recent series of major investments was an in-pit, semi-mobile gyratory crushing unit linked to the Copperton Concentrator by an 8km conveyor system. This reduced haulage distances from the working faces substantially but even so the mine needs a large fleet of Caterpillar mechanical drive and Komatsu electric-drive trucks, mostly of 218t-capacity, to service ten P&H electric rope shovels.
For much of its life, Bingham Canyon was owned by Kennecott Copper Corp. However, during the post-1973 oil crisis shake-out, the company was acquired by British Petroleum, then sold on to Rio Tinto, which operates Bingham Canyon through its 100% subsidiary, Kennecott Utah Copper Corp. The facilities employ about 1,400 people.
In early 2005, Rio Tinto committed $170m to the East 1 pushback project, which will extend the life of the open pit at Bingham Canyon until 2017.
Following research from analysts and investors, Rio revealed in 2008 it was studying deepening the 1.2km pit to shore up an extra 2.83 million tonnes of copper resources.
If this came into fruition, the additional contained copper resources could extend the mine's life from 2019 to 2036, with plans for a subsequent underground mine extending its life even further.
Rio hopes to begin the project in 2009, which is estimated to produce copper valuing about $22.67bn at current prices.
GEOLOGY AND RESERVES
The classic copper porphyry orebody is not only huge but also enjoys a fairly uniform distribution of sulphide mineralisation, mainly chalcopyrite. The existing pit will be worked out by 2013, but open pit and then underground mining will continue after that. As of end-2005, proven and probable open-pit reserves totalled 667Mt grading 0.54% copper, 0.043% molybdenum, 0.32g/t gold and 2.59g/t silver. Total open-pit and underground mineral resources were 960Mt at 0.7% copper, 0.3g/t gold, 0.03% moly and 3.1g/t silver.
OPEN-PIT MINING
The Bingham Canyon pit is now 4km across and very deep. Mining uses a rotary drilling/blasting – shovel/truck – in-pit crushing system, with two to four blasts per day. To contain costs, management has been quick to utilise the most cost-effective drilling, loading and haulage equipment and management tools available.
One of the first of the recent series of major investments was an in-pit, semi-mobile gyratory crushing unit linked to the Copperton Concentrator by an 8km conveyor system. This reduced haulage distances from the working faces substantially but even so the mine needs a large fleet of Caterpillar mechanical drive and Komatsu electric-drive trucks, mostly of 218t-capacity, to service ten P&H electric rope shovels.
Benguérir Phosphates Mine, Morocco
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.
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.
Batu Hijau Copper-Gold Mine, Indonesia
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.
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 micron) inclusions in the copper sulphides.
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.
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.
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 micron) inclusions in the copper sulphides.
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.
Bajo de la Alumbrera Copper and Gold Mine, Argentina
The Bajo de la Alumbrera (Alumbrera) copper-gold mine in Argentina, owned and operated by Minera Alumbrera Ltd (MAA), commenced commercial operation in February 1998. The mine is located in Catamarca province, 1,100km north west of Buenos Aires at an altitude of 2,500m.
The Argentine state- and provincially-owned mining company, Yacimientos Mineros de Agua de Dionisio (YMAD), which has the title to the deposit, awarded an international tender for the Alumbrera concession to International Musto Exploration in 1992. Minera Alumbrera was formed in 1994 when MIM Holdings bought a 50% operating interest. During 1995, North Ltd and Rio Algom acquired shares in International Musto and each took a 25% holding in MAA. Pre-production capital expenditure totalled $1.2bn and capital expenditures in the 1998 and 1999 financial years were $198m and $17m respectively. Royalty payments to Catamarca province commenced in 1998. YMAD will start earning 20% of the net proceeds (before tax) once project capital plus interest has been repaid.
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In 2003, three years after Rio Tinto acquired North Ltd and Billiton (now BHP Billiton) bought Rio Algom, the two companies sold their holdings to the Canadian company, Wheaton River Minerals, while MIM was acquired by Xstrata. In 2005 Xstrata opened an office in Chile, initially to manage both Alumbrera and the company's Las Bambas copper project in Peru.
GEOLOGY AND RESERVES
The Bajo de la Alumbrera deposit is a classic copper-gold porphyry. Porphyritic dacite intrudes volcanic andesite, chalcopyrite being the main copper mineral. Near-surface weathered material overlies primary sulphide. In 2003 the mine's reserve base totalled 330Mt proven grading 0.51% copper and 0.59g/t gold plus 42Mt probable grading 0.55% copper and 0.64g/t gold.
However, 2004 drilling led MAA to reoptimise the mine plan based on a new geological model and new cost figures, and this increased contained metal reserves by more than 20%, extending the mine's life to 2015. In mid-2005, reserves were reported to be 360Mt, grading 0.46% copper and 0.51g/t gold, while mineral resources stood at 380Mt (0.47% copper and 0.51g/t gold).
The Argentine state- and provincially-owned mining company, Yacimientos Mineros de Agua de Dionisio (YMAD), which has the title to the deposit, awarded an international tender for the Alumbrera concession to International Musto Exploration in 1992. Minera Alumbrera was formed in 1994 when MIM Holdings bought a 50% operating interest. During 1995, North Ltd and Rio Algom acquired shares in International Musto and each took a 25% holding in MAA. Pre-production capital expenditure totalled $1.2bn and capital expenditures in the 1998 and 1999 financial years were $198m and $17m respectively. Royalty payments to Catamarca province commenced in 1998. YMAD will start earning 20% of the net proceeds (before tax) once project capital plus interest has been repaid.
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In 2003, three years after Rio Tinto acquired North Ltd and Billiton (now BHP Billiton) bought Rio Algom, the two companies sold their holdings to the Canadian company, Wheaton River Minerals, while MIM was acquired by Xstrata. In 2005 Xstrata opened an office in Chile, initially to manage both Alumbrera and the company's Las Bambas copper project in Peru.
GEOLOGY AND RESERVES
The Bajo de la Alumbrera deposit is a classic copper-gold porphyry. Porphyritic dacite intrudes volcanic andesite, chalcopyrite being the main copper mineral. Near-surface weathered material overlies primary sulphide. In 2003 the mine's reserve base totalled 330Mt proven grading 0.51% copper and 0.59g/t gold plus 42Mt probable grading 0.55% copper and 0.64g/t gold.
However, 2004 drilling led MAA to reoptimise the mine plan based on a new geological model and new cost figures, and this increased contained metal reserves by more than 20%, extending the mine's life to 2015. In mid-2005, reserves were reported to be 360Mt, grading 0.46% copper and 0.51g/t gold, while mineral resources stood at 380Mt (0.47% copper and 0.51g/t gold).
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