Arsenic removal process for refractory gold

15311826613

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Among my country's gold resources, refractory gold accounts for a considerable proportion, among which arsenic-containing gold is a common type of refractory gold. In this type of gold deposit, natural gold is mostly submicroscopically distributed, and some are encapsulated in pyrite, arsenopyrite and other granules. If cyanide extraction is performed directly, the recovery rate is very low, and pretreatment must be performed to decompose the encapsulated minerals before cyanide extraction can be effectively performed.

Gold extraction technology recommendation: Gold flotation process, Gold carbon leaching process, Gold carbon slurry gold extraction process, Gold heap leaching process, Gold gravity separation process

At present, the more mature technology is the oxidation roasting method, which can oxidize sulfur-containing and arsenic-containing minerals to expose gold, but there is SO₂ gas and condensed As₂O₃ particles are difficult to completely remove, which can easily cause environmental pollution; and although the pressurized oxidation method avoids air pollution, the pressurized equipment is expensive and the investment is large.

In order to improve the utilization rate of arsenic-containing gold, after years of research, a new type of arsenic gold ore extraction process has been designed, namely the microbial pretreatment method. This method cannot effectively obtain gold concentrate, but pre-treats the gold ore before cyanidation to improve the gold ore dressing efficiency. Let's take a look at the microbial pretreatment and de-arsenicization process for arsenic-containing difficult-to-select gold ores.

Microbial oxidation pretreatment of gold

The main purpose of microbial pretreatment of arsenic-containing gold ores is to decompose sulfur-containing minerals such as pyrite and arsenopyrite in the minerals. Generally, the oxidation pretreatment of arsenic-containing gold mostly uses autotrophic ferrothiobacillus, which has a good ability to oxidize pyrite and arsenopyrite. The oxidized arsenic enters the leaching solution in the form of trivalent or pentavalent, which is convenient for subsequent chemical fixation of arsenic to avoid environmental pollution. The oxidation mechanism of this pretreatment is: bacteria absorb Fe²⁺ and convert it into Fe³⁺. Ferrous ions act as a reinforcing agent, which can oxidize the arsenic in arsenopyrite from -1 valence to +3 (or +5) valence. At the same time, Fe (III) is reduced to Fe (II), and sulfur is also oxidized into sulfuric acid.

Finally, the gold ore pretreated by bacterial oxidation is fully washed and then cyanide leached for gold extraction. Air is passed through the mechanical stirring, and the leaching is carried out at room temperature for 24 hours. The liquid-to-solid ratio is 4:1, and the cyanide concentration is about 0.08%. The adsorption rate of gold adsorbed by activated carbon in the cyanide leaching solution exceeds 99%.

The above is an introduction to the pretreatment and arsenic removal methods for arsenic-containing refractory gold ores. In the actual beneficiation process, arsenic is the main impurity in gold ore. If arsenic cannot be effectively removed, it will affect the grade of gold concentrate. How to effectively remove arsenic and purify it depends on the properties of the gold ore. Therefore, it is recommended to conduct beneficiation test research and design a reasonable gold extraction process through test analysis.

Xinhai Mining has more than 30 years of experience in gold ore beneficiation. It can conduct beneficiation tests and then design a reasonable gold extraction process for it. At the same time, it customizes complete sets of gold ore beneficiation equipment according to the beneficiation process. If you have any needs, please consult Xinhai customer service, hotline: 15311826613!