The Cortez gold mine is located 100 kilometers southwest of Elko, Nevada in Lander County. The Cortez is found on the southern portion of the Battle Mountain-Eureka Trend in north central Nevada. Cortez Gold Mine is a large gold mining and processing facility in Lander and Eureka County, Nevada, United States, located approximately 75 miles (120 km) southwest of Elko.
Cortez gold mines in Nevada is owned and operated by Barrick Gold and comprises the Pipeline and South Pipeline deposits and the Cortez Hills deposit.The Cortez Pipeline property is 11 kilometers northwest and the Cortez Pediment property (which includes the Cortez Hills deposit) is 4 kilometers southeast of the original Cortez milling complex. The Pipeline and South Pipeline deposits are mined by conventional open-pit methods.
The Cortez property covers approximately 2,800 square kilometers on one of the world’s most highly prospective mineral trends. Pipeline and South Pipeline are open pit mines, while Cortez Hills is an underground and open pit mining operation. Under continuous operation, Cortez has been open longer than any gold mine in the state of Nevada. It is Barrick's and Nevada's largest gold producer.
Mining Operations Cortez Gold Mines In Nevada United States of America
The Pipeline and South Pipeline deposits are currently being mined using traditional open pit mining techniques, while the Cortez Hills deposit be mined out using both open pit and underground mining techniques.
The Pipeline and South Pipeline deposits are currently being mined using traditional open pit mining techniques, while the Cortez Hills deposit be mined out using both open pit and underground mining techniques.
Surface gold mining methods in Cortez Nevada
Mining is carried out with electric shovels, a hydraulic shovel and haul trucks. A fleet of miscellaneous equipment includes rotary/hammer blasthole drills, wheel loaders, bulldozers, graders and water trucks.Ore in the open pit mines is hauled on surface using 400-short-ton (360 t) Liebherr T282B trucks. Cortez currently owns 24 T282Bs, which accounts for 10% of the total sales of T282 & T282B trucks worldwide.
Underground gold mining methods in Cortez Nevada
The underground operation at Cortez Hills utilizes parallel 16 feet (4.9 m) wide by 18 feet (5.5 m) high, 10,000 feet (3,050 m) declines. Crosscuts connect the declines every 500 feet (150 m), the ramps are driven at a grade of 6% for their entirety. The declines are used to haul ore from the stopes to surface and to provide ventilation for the mining operation. The declines are accessed via portals on the wall of an old open pit, the haulage (west) decline brings fresh air into the mine and the east decline exhausts air to surface.
The declines and lateral development utilize welded wire mesh and shotcrete with swellex bolts for ground support. Open stopes will be backfilled with waste rock from the open pit hauled down the decline by empty ore trucks return from surface and mixed with cement underground.
Barrick's Goldstrike Mine utilizes paste backfill, which is an alternative for Cortez in the future which may simplify the backfill process. Once the mine is in full operation it is estimated to have up to twelve production faces in operation producing 1,200 short tons (1,100 t) per day of ore in 2009.
The declines and lateral development utilize welded wire mesh and shotcrete with swellex bolts for ground support. Open stopes will be backfilled with waste rock from the open pit hauled down the decline by empty ore trucks return from surface and mixed with cement underground.
Barrick's Goldstrike Mine utilizes paste backfill, which is an alternative for Cortez in the future which may simplify the backfill process. Once the mine is in full operation it is estimated to have up to twelve production faces in operation producing 1,200 short tons (1,100 t) per day of ore in 2009.
Process Of Gold Mining Cortez Gold Mines In Nevada
Cortez employs three different metallurgical processes to recover gold. Lower-grade oxide ore is heap leached, while higher-grade non-refractory ore is treated in a conventional mill using cyanidation and a carbon-in-leach (“CIL”) process. Heap leached ore is hauled directly to leach pads for gold recovery. Carbonaceous mill ore is mined intermittently during the mining of the Pipeline/South Pipeline deposits.
Low grade open pit ore is heap leached without further crushing at one of the two leach pads currently in operation. The larger leach pad is 3.6 million ft2 (362,000m2) with a 20,000 US gal/min (1,250 l/s) flow rate. The smaller pad is connected to the Pipeline mill and has a flow rate of 6,000 US gal/min (375 l/s). Higher grade ore is processed at the Pipeline mill utilizing CIC/CIL (carbon in column/carbon in leach).Processing of ore from the Pipeline deposits is done by either cyanide heap leaching or milling at the Pipeline mill.
A pit dewatering system including 40 wells helps to prevent water inflows, the water being transported from the pit to a series of shallow infiltration ponds for recycling.The original Cortez concentrator was placed on care-and-maintenance in late 1999, following the change from milling ore to heap-leaching ore from the Pipeline pit. Consisting of crushing, dry grinding, circulating fluid bed roasting, wet grinding and carbon-in-leach gold recovery facilities, it may be re-opened to treat suitable ore towards the end of the mine’s life.
The Pipeline concentrator has a throughput of 8,650t/d, having been designed to handle various types of oxide ore from the Pipeline and South Pipeline orebodies. Its flowsheet consists of primary crushing, autogenous/ball mill (AG) grinding, carbon-in-leach and carbon-in-column gold recovery systems, together with carbon stripping, reactivation and gold refining facilities. Low-grade, run-of-mine oxide ore is heap-leached, with gold-bearing carbon from this section being returned to the main concentrator for gold recovery.
Run-of-mine oxide ore is crushed and stockpiled before grinding in an autogenous mill and a ball mill. Discharge from the AG mill is screened, with screen oversize being conveyed to a cone crusher and recycled to the AG mill. Screen undersize and ball mill discharge are sized in hydrocyclones, the overflow being thickened to provide feed for the carbon-in-column (CIC) and carbon-in-leach (CIL) circuits.
Low grade ore from open pit at the Cortez Hills deposit will be heap leached at dedicated heap leach pads at Cortez Hills site, while ore from the underground mine will be mixed with higher grade open pit and will be sent 10 miles (16 km) to the Pipeline mill via the largest overland conveyor in Nevada.
Low grade open pit ore is heap leached without further crushing at one of the two leach pads currently in operation. The larger leach pad is 3.6 million ft2 (362,000m2) with a 20,000 US gal/min (1,250 l/s) flow rate. The smaller pad is connected to the Pipeline mill and has a flow rate of 6,000 US gal/min (375 l/s). Higher grade ore is processed at the Pipeline mill utilizing CIC/CIL (carbon in column/carbon in leach).Processing of ore from the Pipeline deposits is done by either cyanide heap leaching or milling at the Pipeline mill.
A pit dewatering system including 40 wells helps to prevent water inflows, the water being transported from the pit to a series of shallow infiltration ponds for recycling.The original Cortez concentrator was placed on care-and-maintenance in late 1999, following the change from milling ore to heap-leaching ore from the Pipeline pit. Consisting of crushing, dry grinding, circulating fluid bed roasting, wet grinding and carbon-in-leach gold recovery facilities, it may be re-opened to treat suitable ore towards the end of the mine’s life.
Run-of-mine oxide ore is crushed and stockpiled before grinding in an autogenous mill and a ball mill. Discharge from the AG mill is screened, with screen oversize being conveyed to a cone crusher and recycled to the AG mill. Screen undersize and ball mill discharge are sized in hydrocyclones, the overflow being thickened to provide feed for the carbon-in-column (CIC) and carbon-in-leach (CIL) circuits.
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Low grade ore from open pit at the Cortez Hills deposit will be heap leached at dedicated heap leach pads at Cortez Hills site, while ore from the underground mine will be mixed with higher grade open pit and will be sent 10 miles (16 km) to the Pipeline mill via the largest overland conveyor in Nevada.
Gold Mining Production In Cortez Nevada
The mine produced 902,000 ounces of gold in 2014 at all-in sustaining
costs of $706 per ounce1. In 2015, production is expected to be
825,000-900,000 ounces at all-in sustaining costs of $760-$835 per
ounce.
Proven and probable mineral reserves as at December 31, 2014, were 9.85 million ounces of gold.
Production began at Cortez in 1969 with the Pipeline deposits, where mining is now centred, being discovered subsequently. "Proven and probable reserves in January 2005 totalled 234Mt grading 1.4g/t gold, equivalent to 7.8Moz of gold at 74% recovery."
The Pipeline deposit is situated along the Cortez/Battle Mountain trend in the north-central Nevada basin-and-range province. Submicroscopic gold particles are evenly distributed throughout carbonate host rocks. The two principal lithological units are a sheared and altered thinly-bedded calcareous siltstone and quaternary alluvium varying from chert, argillite, siltstone, limestone and quartzite to fine sands and silts.
Proven and probable reserves in January 2005 totalled 234Mt grading 1.4g/t gold, equivalent to 7.8Moz of gold at 74% recovery. In September 2005, the joint venture approved the development of the nearby Cortez Hills deposit, discovered in 2003, where proven and probable reserves of 64.7Mt at a grade of 1.8g/t gold contain a further 5.5Moz.
A prefeasibility study for underground mining at Cortez below currently permitted levels will be completed in late 2015. Mineralization in this zone is primarily oxide and higher grade compared to the current underground mine, which is sulfide in nature. The limits of the Lower Zone have not yet been defined, and drilling has indicated the potential for new targets at depth. The exploration drift has been extended to the south, enabling additional step-out drilling, which is anticipated to begin in June. Drill results to date include 36.6 meters at 31.5 grams per tonne and 27.4 meters at 20.9 grams per tonne, both oxide in nature, which compare favorably with the average grade of 13.8 grams per tonne in refractory ore above the 3,800 foot level.
Proven and probable mineral reserves as at December 31, 2014, were 9.85 million ounces of gold.
Production began at Cortez in 1969 with the Pipeline deposits, where mining is now centred, being discovered subsequently. "Proven and probable reserves in January 2005 totalled 234Mt grading 1.4g/t gold, equivalent to 7.8Moz of gold at 74% recovery."
The Pipeline deposit is situated along the Cortez/Battle Mountain trend in the north-central Nevada basin-and-range province. Submicroscopic gold particles are evenly distributed throughout carbonate host rocks. The two principal lithological units are a sheared and altered thinly-bedded calcareous siltstone and quaternary alluvium varying from chert, argillite, siltstone, limestone and quartzite to fine sands and silts.
Proven and probable reserves in January 2005 totalled 234Mt grading 1.4g/t gold, equivalent to 7.8Moz of gold at 74% recovery. In September 2005, the joint venture approved the development of the nearby Cortez Hills deposit, discovered in 2003, where proven and probable reserves of 64.7Mt at a grade of 1.8g/t gold contain a further 5.5Moz.
A prefeasibility study for underground mining at Cortez below currently permitted levels will be completed in late 2015. Mineralization in this zone is primarily oxide and higher grade compared to the current underground mine, which is sulfide in nature. The limits of the Lower Zone have not yet been defined, and drilling has indicated the potential for new targets at depth. The exploration drift has been extended to the south, enabling additional step-out drilling, which is anticipated to begin in June. Drill results to date include 36.6 meters at 31.5 grams per tonne and 27.4 meters at 20.9 grams per tonne, both oxide in nature, which compare favorably with the average grade of 13.8 grams per tonne in refractory ore above the 3,800 foot level.
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