Newmont has several deposits but Gold Quarry main producer

Although Newmont Gold Company has more than a dozen gold deposits on its Carlin holdings, about 70% of its production is coming from the Gold Quarry deposit which was first identified in 1979. Development drilling at the nearby Maggie Creek deposit demonstrated that gold- bearing mineralization continued to the east into Gold Quarry.

In subsequent years, a low grade orebody was also blocked out there and a production decision was made in 1984 with a mineable reserve of 144 million tons averaging 0.049 oz gold. The No 2 mill was commissioned in 1985 and a leach facility was later installed for lower grade material.

Two major fault structures coalesce at Gold Quarry which created the environment for gold deposition. The Maggie Creek deposit joins up with Gold Quarry at depth and Maggie eventually becomes the Deep West orebody which is still open to the south and east. Gold Quarry’s depth has still not been established.

Robert Harris, mine superintendent at Gold Quarry, told The Northern Miner recently that approximately 192,000 tons of ore and waste are being removed every day at Gold Quarry. Of that total, 50,000 tons is going to leach pads and about 12,000 tons to the No 2 mill.

Mill grade ore occurs along a fault structure and the lower grade heap leach material in adjacent areas. At the moment, mill grade ore averages about 0.1 oz and leach material approximately 0.03 oz gold. Newmont is mining to a 0.01 oz cut off for leaching ore, he noted. Dewatering will be required in the pit which could eventually reach 1,500-1,800 ft in depth and a mile across at the crest.

On the leaching side, the mine has pretty well converted to a drip system for depositing cyanide solution on leach pads. This will allow leaching right through winter and reduce evaporation loss in summer months. During the winter, solution pipes are buried several feet underground and they are not recovered.

Newmont is pumping about 6,000 gallons of leach solution per minute into its recovery plant and most of the gold is recovered from pads within 4-5 days. In any event, the company aims for a 65% recovery rate in a 2-month period.

Last year, approximately 3.2 million tons of ore was milled and about 9.7 million tons leached which yielded 444,000 oz of gold production. The South Area, which includes the Maggie Creek, Gold Quarry, Tusc and Mac orebodies, plus the No 2 mill and Gold Quarry dump leach facilities, has approximately 9.3 million oz of mineable reserves.

The top portion of the Deep West deposit will be mined from Gold Quarry and Newmont will end up with one large pit on the property which will include the dormant Maggie Creek operation. Only some slide material will have to be removed from Maggie which was stripped in previous mining operations.

Newmont has an incredibly sophisticated computer system for monitoring all parts of its milling operation and there has only been one failure that has shut down the system since 1985. With the exception of possibly the U.S. Air Force, Newmont is thought to be the largest computer user in Nevada. One of its suppliers has a full time staffer on the property and that company carries several hundred thousands dollars worth of spare parts in inventory for use by Newmont.

Newmont is expected to be the largest gold producer in North America in the next few years because of an ambitious 5-year plan that should see production increased to 1.6 million oz per annum. Gold sales this year should be approximately 850,000 oz, an increase of 44% from the previous year.

Cash costs per oz of gold including royalties averaged $172(US) in 1986 and $201 in 1987. At the higher rate, costs are expected to be in the low $170s. In any event, the price of gold would have to go well below $250 per oz before Newmont started hurting.

The company’s geologic reserves are broken down into three main areas: North, South and Rain. As of March 27, Newmont’s reserves totaled 697 million tons representing some 30.9 million oz gold. About 15 million oz of that total has been classified as mineable. But further drilling is bound to upgrade a large portion of the balance into the mineable category.