Biochemical decomposition and gold leaching of refractory ultrafine grinding sulfur concentrates 1

To calcine and firing the basis of cyanide, sulfur concentrate containing gold fine processing technology for analysis. The process can achieve higher indicators in the case of low investment and operating costs, but this is closely related to air pollution caused by toxic compounds of arsenic and sulfur, so further improve some gold extraction from gold-containing sulfur concentrates. Desirable hydrometallurgy and the development of new processes that meet modern environmental requirements are a pressing task.

From the standpoint of developing a roasting-free process, it is important to combine the mechanochemical activation of the ultrafine grinding of the concentrate with the next step of treating the microbial biomass with its alkali hydrolysate to decompose and leach gold.

Contain 30 grams / ton Au , 8.1% As , 24.3% S and 25.4% Fe flotation concentrates were studied for gold biochemical decomposition and leaching processes. Based on reasonable analysis of the information, nearly 6% of Au in sulphide - pyrite and arsenopyrite as disseminated gold. Gold is finely divided in these two minerals, most of which are gold particles with a particle size of no more than 1 micron. Difficult to treat concentrates do not include their direct cyanidation, as direct cyanidation can extract nearly 8 to 10% Au . Even after ultrafine grinding, the extraction rate of gold in cyanide solution does not exceed 23~28% . It is only when the sulfide mineral is decomposed that it is possible to decompose the gold of the pigment, so the hydrometallurgical method is most reasonable.

The alkali decomposition index of the gold-containing sulfide was compared with the index of gold leaching from the concentrate (the arsenic in the planetary gear grinding reaction in the air medium). A periodic speed planetary gear mill was used in the test. Loading more than 35 to 40 times the amount of ground material , and the acceleration is equivalent to 40~ 50 grams . Concentrate 3C The -06 type grinding machine performs jet milling and uses compressed air ( P=4.5~4.7 atm) as the power medium. When the jet is ground, the resulting product has a particle size of 85% of 4 microns and a specific surface area equal to 4.8 meters 2 / gram. The original concentrate has an 80% particle size of 0.074 mm ( no more than 1% of the 4 micron size ).

As shown in Fig. 1 , whether it is the planetary gear grinding or the jet grinding treatment concentrate, the comparison results of the alkali decomposition of the sulfide mineral (sulfur contained in the solution) can be obtained.

However, when gold is extracted from the activated product, a significant difference can be observed. Even when using a cyanide solution, there will be left on the concentrate of the planetary gears (after alkali treatment) 16 grams / ton of gold-containing tailings (Figure 2 ). In this case , the NaCN consumption increases from 0.2 to the original concentrate and the activated ( 20 points and more time) concentrate. 8 kg / ton, this is conditional on improving the reactivity of mineral components. Only in the jet mill, according to the alkali treatment - cyanide process , the highest recovery rate of 65-70% of the gold in the activated concentrate can be achieved. At this time, the remaining content of the tailings gold is one-half less than that of the planetary grinding. . The difficulty of gold cyanidation increases as the leached product of the planet is leached, presumably because of the surface passivation of the gold particles. The authors of this - point reference were observed. Under a further emphasis on jet grinding test.

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