Cerro Casale is a porphyry gold-copper mining project located in northern Chile, South America in mountainous terrain with elevations ranging from 3,800 to 4,400 m. It is located 145 km southeast of the city of Copiapo.
The project is a joint venture between Barrick Gold (75%) and Kinross (25%). The companies use a joint venture vehicle for the project, known as Compania Minera Casale (CMC).
The proposed project consists of a large open pit with a strip ratio of 2:1, a process plant of 160,000 t/d, and an heap leach operation of 100,000 t/d production throughout.
The project is planned to generate 16.8 Moz of payable gold, 4,832 Mlb of payable copper and 36.5 Moz of payable silver in three saleable products: copper concentrate, gold dore, and SART copper concentrate.
The project plans to use the Candelaria port facilities (shiploader and dock) for concentrate shipment. Port facilities are located beside Punta Padrones Port, 7 km from Caldera city.
Proven and Probable Mineral Reserves estimated for 23.2 Moz contained gold and 5.8 Mlb contained copper. Proposed mine life based on the current mineral reserve is 20 years for the mine and 18 years for the process plant. Pre-stripping would start in 2012.
Initial capital cost of the project has been estimated at US$4,184 million with average by-product life-of-mine (LOM) cash costs of US$277 per oz gold payable
Cerro Casale project is located in Region Three (Atacama) of northern Chile. The city of Copiapo is 145 km northwest of the deposit, and the international border separating Chile and Argentina is approximately 20 km to the east.
Chile is a Spanish speaking South American country that occupies a narrow stretch of land on the western side of the continent and it borders the Pacific Ocean for about 4,000 miles.
The country's southern regions - Patagonia - and the Magellan Strait were discovered by the namesake navigator in 1520. The region of Copiapo was settled by Europeans as a result of the 1535 Spanish conquest.
Access to the project is 180 km by road from Copiapo. The initial southbound 25 km is paved highway, which connects to a 155 km gravel road running southeast to the Project site. The nearest commercial airport is located close to Copiapo. Chilean airlines have daily flights to and from Santiago.
Topography in the area varies from 3,500 m in the valley bottoms to over 5,800 m at the headwaters of the Rio Nevado. Project operation is generally possible all year round. The project area is sparsely populated; hence direct impacts on inhabitants will be minimal.
The city of Copiapo is inhabited by 130,000 people mostly employed in mining and agriculture.
The Cerro Casale gold-copper deposit is located in the Aldebarán sub-district of the Maricunga Volcanic Belt. The Maricunga belt is made up of a series of coalescing composite, Miocene andesitic to rhyolitic volcanic centers that extend for 200 km along the western crest of the Andes. The volcanic rocks are host to multiple epithermal gold and porphyry-hosted gold-copper deposits.
The Cerro Casale deposit is considered to be an example of a primary gold-copper porphyry system, with strong affinities to high sulphidation, volcanic-hosted gold systems.
The Cerro Casale deposit is exposed in a hill of approximate 700 m of vertical relief and 1 km in diameter. Mineralization is related to a series of dacitic to dioritic intrusives, which were emplaced into Miocene andesites and volcaniclastic sedimentary rocks.
Gold-copper mineralization occurs in veinlet stockworks developed in the dioritic to granodioritic intrusives and adjacent volcanic wall rocks. Mineralization extends at least 1,450 m vertically and 850 m along strike. It follows west-northwest-trending fault and fracture zones and the main zone of mineralization pinches and swells in width from 250 m to 700 m along strike and along dip steeply to the southwest. The highest-grade mineralization is coincident with well-developed quartz-sulphide stockworks in strongly potassically altered intrusive rocks.
Gold and copper grades generally show a high spatial correlation. Typically, higher copper grades occur in the lower parts of the deposit. Gold occurs in association with copper in the lower parts of the deposit, but at shallow levels gold is present without associated copper.
Oxidation resulting from weathering and/or high oxygen activity in the last phase of hydrothermal alteration overprints sulphide mineralization in the upper portion of the Cerro Casale deposit.
Mining & Operations
The Cerro Casale project area is located in high, mountainous terrain with elevations ranging from 3,800 to 4,400 m. Ore grade material exists on or close to the surface. Considerable pre-stripping will be required to access the deeper, more profitable sulphide ore in the early stages of production.
The mineral reserve has been divided into a sequence of nine pit phases of decreasing profitability in order to facilitate an efficient mining schedule.
The nominal mining rate is 225 Mt/a which is required to provide the nominal 57.6 Mt/a of sulphide mill feed. Mine production and processing facilities will operate 24 h/d, 7 d/wk, 365 d/a.
The mine would operate at a slightly higher cut-off grade during the first five years of mining, and stockpile the marginal grade sulphide ore produced during this period. This would result in a 43 Mt low-grade sulphide stockpile that would be re-handled at the end of the mine life.
Haulage ramps internal and external to the final pit limit are designed to a maximum grade of 10% and to a width of 40 m.
Open pit mining will be carried out with haul trucks and a combination of electric shovels, hydraulic excavators, and large front-end loaders.
The initial production fleet will consist of: Fifty-five 360 t trucks (increasing to 57 between 2022 and 2023); Five 1,200 t class electric shovels; Two 700 t class hydraulic shovels; Two 40 m3 rubber-tired loaders.
A fleet of seventeen 200 mm diesel-powered blasthole drills will drill for sampling and blasting purposes. Three 311 mm electric-drive blasthole drills (increasing to nine between 2016 and 2021) will be required for waste.
Mine road construction will begin in the last quarter of 2011. Pre-stripping of Cerro Casale will commence in the last quarter of 2012, two years before to the initial startup of the sulphide plant, with quantities of sulphide ore sent to stockpile. Oxide ore heap leaching will begin in the last quarter of 2013, a year prior to the initial start-up of the sulphide plant. Initial pre-stripping of 83 Mt of waste material is required before the start of gold production from the heap leach. The heap leach pad will receive ROM oxide feed over a six-year period.
The sulphide concentrator is planned to come on stream during the fourth quarter of 2014 and will build-up to its full production rate of 160,000 t/d (57.6 Mt/a) by the fourth quarter of 2015, assuming a pre-stripping start during the last quarter 2012. The mine life of the current mineral reserve is 20 years. Sulphide ore stockpiled during the pre-stripping period will be reclaimed partly during the first year of production.
Approximately 2,231 Mt of waste will be mined over the life of the proposed mining operation. Of this total, approximately 170 Mt of waste rock were scheduled for tailings dam construction over the mine life. It is proposed to mine waste rock by a conventional truck and shovel operation using 360 t end-dump trucks. The average peak waste dump production rate is about 475,000 t/d.
The Rio Nevado Valley east and southeast of the open pit is well situated and able to contain the open pit waste. The Tailings Storage Facility has been designed to store 930 Mt of rougher tailings and 97 Mt of cleaner tailings. Tailings production will begin in Q4 2014 and continue until 2033 providing a 20 year period of TSF operation.
Suitable water supply is available from the presently permitted Piedra Pomez well field that is located 121 km north of the project. Water would be delivered through a pipeline to the mine site.
Sulphide ore will be processed in a 160,000 t/d flotation plant facility designed to recover a copper/gold flotation concentrate, followed by dewatering and then dispatch via a 220 km concentrate pipeline to a filtration plant adjacent to a port facility. Filtered concentrate will be loaded into sea-going vessels and shipped to smelters overseas. Additional gold metal will be recovered by submitting the flotation cleaner tailings to a cyanide leaching stage.
Oxide ore will be processed in a 100,000 t/d ore heap leaching facility treating run-of-mine material. Ore placement rate from the mine will periodically reach 150,000 t/d.
Gold-loaded carbon from the heap leach facility, as well as carbon originating from the processing of the cleaner tailings will be processed to produce gold doré bars for shipment and final treatment off site. The carbon handling area for the loaded carbon will consist of an acid wash circuit and a modified pressure Zadra circuit for stripping carbon.
The crushing and grinding circuits consist of two parallel gyratory crushers; eight cone crushers; six HPGR units; and, six parallel ball mills. Concentrate is produced by six parallel lines of eight 300 m3 rougher flotation cells.
The SART circuit (sulphidization, acidification, recycling, and thickening) is a relatively recent commercialized process that allows recovery of copper dissolved by cyanide and the recycling of cyanide.
The SART circuit includes a filter press, dryer and bagging system that will allow shipment of copper precipitate in 1 tonne tote bags on trucks to domestic smelters.
Cerro Casale will produce and sell copper/gold concentrate, gold dore and SART copper sulphide concentrate to generate revenue for the project. Over the life of the mine the flotation plant will produce 8.2 million tonnes of concentrate containing 13.44 M oz payable gold and 4,832 Mlbs payable copper. The CIL and heap leach plants will produce dore containing 3.35 Moz gold and the SART copper sulphide concentrate will contain 73 Mlbs payable copper.