Barrick Gold Production Description

Gold amost always occurs in the native state. It is recovered from alluvial or placer deposits, from veins associated with quartz and various sulphides, or from refining residues of nonferrous metals. Alluvial or placer deposits are formed by mechanical processes, such as the weathering and disintegration of mineral-bearing rocks, and subsequent transportation and concentration by running water. Veins (also known as reefs) are the parent bodies of alluvial deposits. These deposits must be crushed and finely ground before being leached. Gold is also a by-product of copper and nickel refining.

As time passes and the world's supply of easily worked gold deopisits diminish, gold mining and related processing techniques are becoming more and more sophisticated. Barrick Gold Corporation is a leading international gold producer with five mines in North and South America.

Goldstrike Property:

The flagship Goldstrike Property is located on the rich Carlin Trend of north-central Nevada. Current operations consist of the Betze-Post open pit mine and the high-grade Meikle underground mine. In addition to these mines, the Property hosts other gold deposits, including Griffin, Rodeo, and Goldbug.

The new Goldstrike Roaster, scheduled for full operation by mid-2000, is based on Freeport McMoran Inc. roaster technology, and includes a dry grinding circuit, a carbon-in-leach (CIL) circuit, gas scrubbers, and a stand-alone low-pressure oxygen plant.

The Goldstrike Property has produced 14 million ounces of gold since 1987 and still has 27.3 million ounces in reserves. Production will total two million ounces a year well into the next century. At the time of purchase in 1986, the principal known deposit was the Post surface oxide deposit containing 600,000 ounces of gold. Goldstrike's reserves at December 31, 1998 totaled 27.3 million ounces, after total production of 14 million ounces of gold under Barrick's ownership.

Pierina Mine:

The Pierna Mine is located in the Andean Cordillera in the Department of Ancash, in north-central Peru. Pierina utilizes Heap Leaching to extract gold.

The process facilities consist of a valley-fill heap leach pad and a conventional Merrill-Crowe gold and silver recovery plant. The ore is stacked in a lined containment area behind a retention dam. A leach solution is applied to the top of the ore and allowed to percolate through the heap. As the solution migrates through the ore, it leaches the gold and silver from the rock and holds it in a solution. The gold-bearing solution ("pregnant solution") is collected at the base of the leach pad in the pore space within the heap. The pregnant solution is pumped to the gold recovery plant where suspended solids are removed and the solution is then treated in a conventional Merrill-Crowe precious metal circuit. The same valley-fill system was successfully used at Barrick's Mercur Mine in Utah.

The Bousquet Mine and Est Malartic Mill:

Barrick Gold Corporation owns and operates the Bousquet Mine, located on the Abitibi Belt in northwestern Quebec, 40 km west of the town of Malartic. The Bousquet ore is in the form of veins. The gold mineralization is related to massive pyrite veins and shows a strong relationship to pyrite and copper content. Massive sulphide mineralization is composed of 30% to almost 100% pyrite in bands several feet thick with minor amounts of copper.

Once mined, the Bousquet ore is trucked to the Company-owned Est Malartic mill, located 35 km from the mine. The mill has a capacity of 3,000 tonnes per day and includes: conventional crusher-rod mill-ball circuits; Knelson gravity circuit; copper flotation circuit; cyanidation leach with a Merrill-Crowe precipitation circuit; and sulphur dioxide cyanide destruction circuit. At this mill, the Cyanidation Process is employed to leach the gold from the gangue minerals.

Holt-McDermott Mine:

Holt-McDermott, also on the Abitibi Belt, is an underground mine in north-eastern Ontario, 48 km from the city of Kirkland Lake.

The Holt-McDermott processing plant is a conventional carbon-in-leach mill circuit with a design capacity of 2,200 t/d. Modifications were made in 1998 to increase the capacity to 2,500 t/d. In addition to processing Holt-McDermott ore, the facilities process ore from other mines on a custom milling basis.

Pascua Mine:

The Pascua Mine Project is located at the northern end of the El Indio Belt, straddling the Chile-Argentina border in Chile's Region III and Argentina's San Juan province. The engineering for the Pascua Project is nearly complete, and construction of a mine and process facilities is iminent.

The circuit will consist of crushing, grinding, counter current decantation (CCD) washing to remove the soluble salts, cyanide leaching, CCD Merrill-Crowe, retorting, electrowinning and fire refining to produce gold doré. These facilities will be capable of treating oxide and sulphide ore; the copper sulphide minerals will be floated and tails routed to the cyanide leach circuit. The majority of the gold from the sulphide ore will be recovered, but some will float with the copper for treatment in a smelter. Heap leach of low-grade ore is also being investigated.

Flow-Sheet: To examine flow-sheets for gold production, click here or on the picture at left.