Pretreatment technology of refractory gold

The common alternatives two Mexican refractory ores in order to increase the gold for the pretreatment of refractory ores are roasting, high and silver extraction. Two methods for contacting ozone with the mineral were studied indirect and direct.

Pretreatment technology of refractory gold

The difficulty is usually more of a physical than a chemical one but special methods of treatment may be required.

Mispickel in the raw condition in an ore, when agitated with strong concentrations of lime or other alkali in the presence of air, can yield alkaline arsenites, thus: Pretreatment technology of refractory gold high concentrations of lime are used, the associated gold may be released, but difficulty may ensue in dissolving the gold owing to lack of oxygen.

It is therefore indicated that minor amounts of lime be used in solution, sufficient to provide a permanent alkaline pH for protection of the small amounts of sulphantimony compounds formed, otherwise attacked by the latent acidity of the ore to liberate antimony pentasulphide and hydrogen sulphide, which would act as powerful cyanicides.

Use of low-cyanide-strength solutions is also advisable in order to minimize the speed of disequilibrium of the alkaline cyanide ions.

The ore should be pulverized only to a sufficient degree to render the gold particles open to cyanide attack, thus presenting a minimum stibnite surface area for interferent reactions.

Gold Sulphide Ore Oxidation by Alkaline Pressure Some stibnite gold ores are more amenable to cyanidation when previously subjected to surface oxidation in the pulverulent condition, with the formation of a sulphate film, which on contact with water yields an insoluble basic sulphate.

The oxidation may also open up the fissure planes, setting free the associated gold. If an antimonial ore or concentrate is roasted before cyanidation, this calls for meticulous temperature and air control, as reduction to the molten metallic condition can occur, with enfoldment of the gold particles.

When ordinary water-slaked lime was used in the cyanide treatment of tailings from previous milling operation, the gold extraction was fair but the cyanide consumption was 12 to 14 lb.

The present ton treatment plant consists of agitation and decantation equipment—an ft. Sufficient lime is added for the proper degree of alkalinity. The batch is then stirred for 4 hr.

The mixer handles two batches per day. The four agitator vats are 16 ft. Before running a batch into an agitator, a large quantity of sump solution is first pumped in, and the proportion of solution to solid is kept high.

After receiving two batches from the mixer and given a double wash, the agitators are discharged, hosed clean, ready for the next batch. The clear solution drawn off from an agitator is run to two settling vats 16 ft.

Pretreatment technology of refractory gold

The solution stands in settlers until any cloudiness has settled. It is then run through a sand filter and then to the zinc boxes. An 80 per cent gold recovery was made by the method of treatment described. It is generally known that antimony can be readily volatilized, and by roasting stibnite Sb2S2 in an oxidizing atmosphere, antimony oxide can be driven off and condensed.

At the same time, anyone who has had experience with such roasting knows that it is a delicate process. To begin with it is impossible to drive off the antimony completely. Furthermore, unless temperature control is very exact, the ore being roasted is liable to be fused into a solid mass, entirely hopeless as regards subsequent roasting or treatment.

Provided the roasting is carefully done, the scoria remaining, which contains the gold, also contains a residual amount of antimony which still stands in the way of normal cyaniding, as the gold is, if anything, still more intimately associated with it. The treatment of the calcines with an alkaline leach for the conversion of the residual antimony oxides to soluble antimonates has been proposed as a method for overcoming the difficulties usually encountered in attempting to cyanide such material.

At the plant of the Consolidated Murchison Co. The association of the antimony and gold is very intimate, and duringwhile the antimony recovery amounted to The gold-bearing tellurides behave very much as does gold itself.

Pretreatment technology of refractory gold

Finely divided particles are dissolved fairly rapidly; coarser particles more slowly. The ordinary high-lime solution of Kirkland Lake practice is suitable for dissolving of the gold tellurides.

Oxygen is necessary but apparently not more so than in dissolved gold. Before detailing these he says that a search of the literature failed to show that anyone had actually conducted cyanidation tests on either specimen tellurides or those concentrated from an ore—meaning Kalgoorlie, Cripple Creek, and Kirkland Lake.

Experiments with cyanide on these ores gave the following conclusions, with which A. Wallace, and John Dixon of Kirkland Lake substantially agree: Gold-bearing tellurides do yield their gold to cyanide if they are in a finely divided state and excess lime is used.

Sodium peroxide greatly reduces the time of treatment required for maximum extraction. It is not beneficial when used in quantities equivalent to commercial use.

The tellurides are very brittle and, owing to their high gravity, will be retained in the mill circuit for a long time. They will thus be in a finely disseminated state, approximately minus mesh or the size required to yield a maximum extraction of their gold.

Up to the present, gold-bearing tellurides have not been found in large quantities in mill tailings or in concentrates recoverable from them. As in the case of many arsenopyrite ores, however, those carrying tellurium and sulphotellurides often require roasting in order to open up the gold content to attack by cyanide solutions.The common pretreatment methods for gold sulfide gold deposit are oxidizing roasting method, curing method, acid pressure oxidation, bacterial oxidation method, nitric acid oxidation method, etc.

Gold ore which is difficult to concentrate often referred to gold or refractory gold ore, which use conventional cyanide process cannot effectively extract most of the gold ore. Abstract: On one hand, refractory gold concentrate with high arsenic is one kind of pollutants; on the other hand, it contains a lot of valuable metals, so it is very important to utilize it.

This paper studies the optimization of the nitric acid pretreatment refractory gold concentrate process with. oxidation as a pretreatment method for refractory gold ores has been published by Berezowsky and Weir (6). According to them, the first patent the technology of pressure hydrometallurgy, Sherritt Gordon have carried out much of the recent pressure oxidation work on refractory gold ores.

In the recovery of gold from refractory gold ores, pretreatment is required to decompose sulphides and liberate occluded gold before cyanidation, and to deactivate carbonaceous matter and prevent it from adsorbing dissolved gold.

The U.S. Bureau of Mines is investigating the treatment of refractory gold ores. Chlorination in the treatment of refractory gold ores is applicable in many low-grade gold operations. When usable, this treatment provides an economic means of consuming sulfides and deactivating disseminated organic carbon.

Chlorination, however, is a pretreatment technique that requires the neutralization of the. Pretreatment Process on Refractory Gold Ores with As Xin-yuan NAN, Xin CAI* and Jun KONG School of Electrical Engineering, Xinjiang University, Yan’an Road, Tianshan District, Urumqi, P.


technology to enhance gold recovery for double refractory ore