In 1986, the Fairview Gold Mine of South Africa's Jinke Company established the world's first bacterial oxidation gold extraction plant. The leaching rate of gold is over 95%. The Tomkin Spytins gold mine in Nevada, USA, was built in 1989. It has a daily processing of 1500 tons of gold ore and a gold recovery rate of 90%. In 1995, the bacterial oxidation pretreatment project of the refractory gold mine in Zhenyuan gold mine in Yunnan was started, and the first microbial leaching gold factory in China was built. After the bacterial oxidation pretreatment of the Baogutu gold deposit in Xinjiang, the leaching rate of gold is as high as 92%-97%. In December 2000, Yantai Gold Smelting Co., Ltd. took the lead in the treatment of gold mines with bio-oxidation pretreatment technology, which resulted in a recovery rate of 96% and a treatment volume of 60 t/d. The CCD process adopted by Laizhou Gold Smelter has a production capacity of 100t/d and was completed and put into operation in April 2001. In July 2003, Liaoning Tianli Gold Industry Co., Ltd. was completed and put into operation.
1 refractory gold mine is difficult to handle
There are many difficult factors for refractory gold mines. This article gives a brief overview from the following aspects.
(1) Physical aspects. Natural gold is entrapped in the symbiotic minerals, and the particles are fine, even in the micron-grain class. It is difficult to expose the gold by the grinding method, and the gold particles are not easily dissolved in contact with the leachate.
(2) Chemical aspects. Metal sulfides in gold ore and other harmful substances that interfere with cyanide can chemically react with cyanide, oxygen or alkali in the slurry and consume the leaching agent. E.g. iron containing mineral particles is formed on the gold film ferric hydroxides, hindered gold dissolution, minerals containing copper cyanide consumption, generated secondary particle surface a thin film of gold, gold dissolution hinder the fatigue soon enter cyanide.
(3) Physical chemistry, electrochemistry and other aspects. The presence of carbonaceous matter and clay in the ore will adsorb dissolved gold on the one hand, and also adsorb cyanide and interfere with the cyanidation process. In addition to the possibility of coating the gold particles, metal sulfides and the like have a certain conductivity, and when they are in contact with the gold particles, the anode of the gold is dissolved and passivated.
2 gold mine microbial treatment type
Different types of gold deposits for microbial pretreatment have different opinions. According to the reasons of difficult treatment, it is divided into the following categories: The first category is gold-bearing sulfide ore. As carriers are gold sulfide mineral pyrite, arsenopyrite, chalcopyrite, arsenopyrite, galena like. Gold is often encapsulated in these minerals in solid solution or submicroscopic form, and it is difficult to dissociate by fine grinding. When direct cyanidation is leached, cyanide ions cannot contact gold particles. The second category is a gold-bearing gold ore that contains a certain amount of carbonaceous materials, including gold in organic and inorganic carbonaceous carbons that are difficult to cyanide, and carbonaceous materials that dissolve gold in cyanidation. There is a strong adsorption, the so-called noble liquid immersion phenomenon or called gold robbing phenomenon. In addition, humic acid generated by organic carbon has a certain interference effect on the cyanidation process. The third category is a clay type gold deposit. Ore contains a considerable portion of the clay mineral, ore processing will produce a lot of fine mud and inevitable ion fourth category gold telluride.
3 Microbial pretreatment refractory gold ore mechanism
At present, most of the oxidatively pretreated gold ore is a refractory sulfide gold ore. The mechanism of pretreatment of refractory sulfide gold ore by bacteria is still controversial. It is generally accepted that the direct indirect mechanism leaching process has both direct leaching of attached bacteria and bacterial metabolite Fe 2 (SO 4 ). 3 ) Indirect leaching. It can be expressed as a closed loop of Fe 2+ ---Fe 3+ , and the sulfide mineral is continuously oxidized until it is completely oxidized, so the gold is dissociated.
Come. The oxidation mechanism of gold-bearing minerals such as pyrite and arsenopyrite is taken as an example to illustrate the mechanism of bacterial oxidation.
The direct action mechanism of direct contact of bacteria with minerals:
Indirect mechanism of indirect contact of minerals with bacteria:
The advantages of microbial treatment in gold mines are:
(1) Process standardization, the scale of sorting can be expanded only by increasing the sorting tank;
(2) There is no air pollution;
The disadvantages of microbial treatment in gold mines are:
(3) The reaction rate is slow, such as effective pretreatment of sulfide ore concentrate may take several days;
(4) Care should be taken to control and regulate the temperature;
(5) There may be blistering;
(6) Excessive acidity of the slurry may cause corrosion;
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Photo of our Marine Buoy:
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Form
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