79 Group Top News

Alternative Ore Processing

Newmont Mining Launches Alternative Ore Processing Plant:
Newmont Raises $2.5 Billion Upon Closing of Senior Notes Offering

DENVER, March 8, 2012 /PRNewswire/ -- Newmont Mining Corporation (NYSE: NEM) (the "Company") today announced that it has received aggregate net proceeds of approximately $2,46 billion, after deducting underwriting discounts and estimated expenses, upon the closing of its registered public offering of $1.5 billion principal amount of 3.500% senior notes due 2022 and $1.0 billion principal amount of 4.875% senior notes due 2042 (the "Notes").

The Notes are senior unsecured obligations of the Company and rank equally with the Company's existing and future unsecured senior debt and senior to the Company's future subordinated debt. The Notes are guaranteed on a senior unsecured basis by the Company's subsidiary, Newmont USA Limited.

The Company intends to use the net proceeds of this offering for (i) repayment of the outstanding balance under its senior revolving credit facility (which was drawn upon in January and February 2012 principally to repay the Company's 2012 convertible senior notes and to pay a portion of the payments in connection with the exercise of the early purchase option under the sale-leaseback agreement relating to the Company's refractory ore treatment plant in Nevada), (ii) settlement of certain forward starting swaps contracts, (iii) remaining payments to be made during 2012 in connection with the exercise of the early purchase option under the sale-leaseback agreement relating to the Company's refractory ore treatment plant in Nevada, and (iv) general corporate purposes (which may include funding associated with exploration, the development of the Company's project pipeline or dividends or other forms of capital return to the Company's shareholders). The Company intends to place the remaining proceeds in short-term liquid investments.

Citigroup Global Markets Inc. and J.P. Morgan Securities LLC acted as the joint book-running managers for the offering. Copies of the prospectus supplement and accompanying base prospectus for the offering may be obtained from Citigroup, Brooklyn Army Terminal, 140 58th Street, 8th floor, Brooklyn NY 11220 or by telephone at (877) 858-5407, or J.P. Morgan, 383 Madison Avenue, New York, NY 10179, Attn: Investment Grade Syndicate Desk – 3rd floor, or by telephone at (212) 834-4533. An electronic copy of the prospectus supplement and accompanying base prospectus may be obtained at www.sec.gov.

Newmont Mining Alternative Ore Processing Steps

We at Newmont Mining use alternative gold recovery methods in some processing plants to accommodate different ore characteristics or other requirements. For example, ore that has a high level of sulfide minerals or carbon (or both) is called refractory ore. Refractory ore resists normal processing methods as the high sulfide minerals trap gold particles, making it difficult for the cyanide to reach the gold and leach it.


To leach gold from refractory ore, it must be subjected to high temperature, high pressure and/or oxygen. Newmont treats refractory ore in two ways: by using an autoclave or a roaster.

An autoclave is used before leaching occurs. First, the slurry is heated and fed into an autoclave, where high-pressure steam, water and oxygen are applied to oxidize the sulfide material by a chemical reaction. The slurry is then cooled and sent back into the process to be leached.

An alternative to an autoclave is a roaster, a very high temperature oven that is often used instead of an autoclave if the ore to process contains a large amount of organic carbon. Roasting uses heat and air to burn the organic carbon into fuel and to burn the sulfur off ore, which we heat to 932 to 1,202 degrees F.

Heap leaching

In heap leaching, we dump crushed ore into piles called heaps, where we applya weak cyanide solution, using drip feeders, to the ore. The gold dissolves into the cyanide solution. The entire heap leach area is lined with heavy duty liners to ensure no solution leaks into the environment. Next, we collect the gold-cyanide solution in ditches and ponds, and then transport it to a recovery plant.


Flotation is a method of separating minerals depending on their ability to attach to air bubbles.

Flotation can be used for a number of materials by adjusting the chemicals. At Newmont, it is used for copper recovery and, in a very limited number of cases, for gold processing.

We introduce air bubbles to the slurry while it is in small tanks, called flotation cells. We add some chemicals to the slurry to assist the process. The desired minerals stick to the bubbles and rise to the top, resulting in froth. The froth overflows from the tank, and is removed and sent to the next step in processing.

Gravity circuit

A gravity circuit recovers course gold before it is leached. Gravity circuits use the same principles as gold panning: course gold is heavier than other material and will settle to the bottom so that it can be removed (gold is 19.3 times heavier than an equal volume of water).wn risk.


SOURCE Newmont Mining Corporation

Posted by 79Group.com on 2/15/2013 10:56:15 AM