Mechanism of bacterial heap leaching

Although bacterial heap leaching has been applied in the production practice of uranium and copper , the views on the role and mechanism of bacteria in heap leaching are not uniform. Some people think that it is a direct effect, some people think it is an indirect effect, and hold the latter view. People think that bacteria do not react directly with uranium, copper, etc., and bacteria should not be regarded as leaching agents of uranium and copper. At present, the tendency is that bacteria oxidize sulfide ore in ore to produce sulfuric acid and high - sulfur sulfate; high-sulfur sulfate is a good oxidant for low-grade uranium and copper sulfide ore, and sulfuric acid is a leaching agent for uranium and copper. Further, while the sulfur bacteria of the mine, the destruction of the original ore and the lattice structure, so that the original wrapped metal leaching solution is exposed, so that when a conventional metal does not leach heap leaching dissolution is improved Leach rate.

For bacterial heap leaching of uranium ore, the following chemical reactions are generally used:

2FeS 2 +2H 2 O+7O 2 2FeSO 4 +2H 2 SO 4 (1)

4FeSO 4 +2H 2 SO 4 +O 2 2Fe 2 (SO 4 ) 3 +2H 2 O (2)

2S+2H 2 O+3O 2 2H 2 SO 4 (3)

Fe 2 (SO 4 ) 3 +UO 2 UO 2 SO 4 +2FeSO 4 (4)

The ferrous sulfate produced by the reaction formula (4) is oxidized again according to the reaction formula (2), and is circulated until the end of the leaching.

The chemical reaction of bacterial pretreatment of gold encapsulated in arsenopyrite is as follows:

4FeAsS+13O 2 +6H 2 O 4H 3 AsO 4 +FeSO 4

4FeSO 4 +2H 2 SO 4 +O 2 2Fe 2 (SO 4 ) 3 +2H 2 O

Fe 2 (SO 4 ) 3 +2FeAsS+4H 2 O+6O 2 2H 3 AsO 4 +4FeSO 4 +H 2 SO 4

The so-called bacterial pretreatment is essentially bacterial arsenic pyrite, which dissociates the gold encapsulated by arsenic pyrite. Therefore, in the experiment and production, the degree of arsenic removal in the pretreatment of the ore is often determined. The later ore is then subjected to gold cyanide leaching. It can be seen that when the bacteria are immersed in gold ore, the bacteria are not directly involved in the gold leaching process.

Scholars with direct effects often point out that the nickel ore is corroded by bacteria, nickel is dissolved, and the amino acid metabolite-amino acid can directly dissolve gold as an example to prove the correctness of their views. We believe that the role of bacteria in uranium, copper, and gold heap leaching is indirect; for sulfur, iron, and arsenic in ores, it is a direct effect.

The Whole Tyre Crusher

Model: XY-SH800  /  XY-SH1200

 

Specifications:

At the room temperature, put the tyre or large plastics of rubber into the press directly,which can be crushed into 1-8cm pieces.

 

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Tyre Shredder

Tyre Shredder,Tyre Crusher,Tyre Shredding Machine

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