Treatment of copper-bearing tailings by bacterial leaching of Shuikoushanbaifang copper mine

Shuikoushan Mining Bureau BEIFANG copper mine, surface lean ore and tailings piled up a lot of copper and rare metals. In recent years, with the help and guidance of the Institute of Microbiology of the Chinese Academy of Sciences, research work on the recovery of copper and rare metals from tailings with sulfuric acid 1 bacteria has been developed and officially put into production in 1972.

The production practice in the past few years proves that the process of leaching out of ore by sulfuric acid 1 bacteria can comprehensively leaching copper and rare metals in ore, with high recovery rate, simple operation, less equipment and low cost, which is a waste and treasure. An effective way to benefit and comprehensively utilize mineral resources. The characteristics of the mine containing copper tailings are: rare metals accompanying copper, the ore is acidic, but the gangue carbonate content is high, the grain size is fine (1 mm), it is sticky, and the percolation performance is poor.

The copper-containing tailings have three parts: flotation Kunsha, re-selected tailings and slime, which are currently treated. Flotation tailings, with a particle size of 99% -20 mesh, good percolation, can be directly leached separately. Re-selected tailings, with a particle size of -2 mm, accounting for 95%, better percolation, and can be directly treated separately.

The slime is formed by the fine particles of the flotation tailings and the re-selected tailings. It is fine-grained and cannot be diafiltered separately. Therefore, it is mixed with heavy sand (1:1).

(1) Bacterial culture

Copper is the use of bacteria isolated Tongguanshan screened No. 9 iron oxide Thiobacillus strain, the bacterial culture medium using the kernel-free iron sulfoxide column.

(2) The percolation leaching flotation tailings contain 0.11~0.2% copper, and the re-selected tailings contain 1.25~1.5% copper. Both tailings contain rare metals.

Because the tailings are fine in size and difficult to percolate, the leaching tank is used for production. The alkaline gangue in the acidified water and ore is first added. When the pH of the solution reaches about 2.0, the immersion of high-iron (Fe 2+ ) is added. Mineral or leaching of lean liquid (referred to as copper and rare metal reduced, higher Fe 2+ leachate) is circulated until the copper and rare metals in the leaching solution are lower. Then, the copper high-iron liquid with extremely low metal content is added, and when the concentration of the leaching solution is lower, it is washed with water for two or three days. The tailings leaching time is twenty days.

(3) Copper recycling

The tail liquid after adsorption of rare metals contains about 2 to 1.5 (g/L) of copper, and the copper is recovered as sponge copper by using iron or scrap iron displacement deposition method. The operating conditions of the replacement process are:

A. The higher the copper content of the replacement liquid, the better, the iron content should be reduced as much as possible, pH=1.8~2.0

B. When the solution pH is around 1.5 and the copper concentration is between 2 and 4 (g/L), the iron consumption ratio is 1.5 times that of copper. When the pH is about 2 and the copper concentration is high, the iron consumption is 1.5 times that of copper.

C. Displacement time is related to temperature, scrap iron quality and quantity, solution acidity and displacement type. Generally, it can be replaced in 9 hours under the condition of temperature >20 0 C ventilation.

D. Immediately after the replacement, the tail liquid is discharged, and the Fe 2+ concentration and acidity in the tail liquid are adjusted to be used as a bacterial culture solution.

(4) Main technical and economic indicators

The total recovery of rare metals is 75-80%, and the total recovery of copper is 70-75% (the yield of 75-80 is 90-95%). Sponge copper contains 60-65% copper, 40-45 kg of sulfuric acid per ton of minerals, and 2.5 tons of copper per ton of copper is 2,000 yuan per ton of copper.

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