(1) copper officer mountain old mining district of bacterial leaching test mining industry
1 Overview of the leaching area The leaching area is the old mining area of ​​the 5 m section of Songshan Mountain. The surface has fallen, and the ore body belongs to the high-middle temperature hot liquid metasomatic deposit in the contact zone, and the ore belongs to the middle and late oxidation stage of the sulfide ore. The sulfation is more intense, and the phase composition is complex, including two parts, the surface covering and the residual ore. The surface coverings include iron cap, red clay layer and yellow clay layer. The iron cap has a copper grade of 0.2~0.5%, and the clay layer contains a copper grade of 0.2~0.25%, all of which are low grade ore. Due to the low-grade, metal complex storage conditions, it can not yet be used by the current mining industry. In the residual ore, the primary sulfide ore is mainly pyrite and copper-bearing pyrrhotite, accounting for 34.2%, and oxidized ore (including secondary sulfide ore and copper oxide) accounts for 35.1%. Iron caps account for about 30.7% of copper.
Songshu Mountain has been exploited since the Tang Dynasty. There are a lot of hollows in the ore body. The mining method has been used for mining above 5 meters, so the top plate and the surface covering have fallen. Covering vegetables and pines is good for water seepage, which is an advantageous condition for leaching. The unfavorable conditions are: the surface is not flat, the cloth liquid is not uniform, the residual ore is covered and the bacteria liquid is difficult to enter.
2 Process The ferrous sulfate is oxidized into a high-iron sulphate leaching solution by the catalytic action of the organism. The spraying liquid method is used to sprinkle the bacterial liquid into the surface percolation field, and the leaching solution is leached through the surface covering and the residual ore. The leaching liquid is collected from the original mining tunnel in the water tank and pumped to the surface with acid resistance. The copper-rich liquid enters the iron replacement column for iron replacement to produce powdery precipitated copper; the tail liquid is mixed with acid and injected into the bacterial regeneration tank, and the aerated bacteria oxidize Fe 2+ to Fe 3+ to prepare the bacterial liquid. The bacterial liquid and the excess tail liquid are mixed and acidified, and then raised to the surface to spray the leaching. Lean ore liquefaction is added to the replenishing water (shown below). [next]
Bacterial leaching process in the old mining area
3 Percolation technical parameters Total iron, Fe 2+ , Fe 3+ concentration and ratio in leaching solution:
Separation was carried out with leaching solutions of total iron concentrations of 2, 4, 6, 8, 10 g/l and different ratios (Fe 2+ and Fe 3+ ), wherein pH = 2.0 ± 0.05.
By comparison, the leaching solution has a better leaching effect when the pH of the leaching solution is 2.0±0.05, Fe=6 g/L, Fe 2+ = 3 g/L, and Fe 3+ = 3 g/L. Exceeding this indicator is not significant. However, in the field test, the total iron concentration can only reach 1.5-3 g / liter. Only the ratio of Fe 2+ and Fe 3+ can be controlled, and it is necessary to further explore ways to increase the concentration of total iron. [next]
Percolation strength and wheeling system The amount of water sprayed per unit area (diafiltration intensity) directly affects the leaching scale and copper ion concentration of the leachate. When the mine uses a water spray of 1 m 3 per hour at 100 m 2 , the final average grade of the leachate will increase by about 15%, and the acid consumption will also decrease accordingly. Therefore, the percolation strength is pushed to be 1 m 3 per 100 m 2 per hour. Should fall. Therefore, the percolation strength is recommended to be 1 m 3 per 100 m 3 per hour.
Due to the ongoing experiment, the cycle of rotation is still to be explored.
1 Main indicators of industrial test The percolation field irrigation area is about 4000 m 2
Average leaching liquid production 368 m 3 /day Average Cu concentration 0.41 g / liter Monthly leaching copper volume 4610 kg Maximum leaching copper volume 323 kg / day Leachate loss rate 40-50%
The average grade of tail water is 0.067 g / liter. The recovery rate of copper is 93%.
Sponge copper grade 60% or so (2) Shuikou Shanbaifang copper mine with bacteria leaching treatment of copper tailings Shuikoushan Mining Bureau Baifang copper mine, a large number of poor ore and tailings containing 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-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. [next]
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 grade of tailings and the composition of the copper mineral phase are listed in the table below.
The process of bacteria participating in the sulfuric acid high-iron leaching tailings is shown in the figure below.
Bacterial leaching treatment tailings process
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The copper-containing tailings have three parts: flotation Kunsha, re-selected tailings and slime, which are currently treated.
Flotation tailings, 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 The strain is a strain of Thiobacillus ferrooxidans No. 9 which was isolated and selected from the Tongguanshan copper mine. The bacterial culture was carried out using a renji-free medium. The culture conditions are shown in the table below.
It can be seen from the above table that when the conditions of Fe 2+ concentration, temperature and pH are almost the same, the speed of bacterial ferrous oxide is greatly related to the inoculum amount, in order to rapidly culture the bacterial high-iron leaching agent and reduce the pressure wind power. Consumption should be expanded or continuously cultured.
2 Percolation leaching Flotation tailings contain 0.11~0.2% copper, and re-selected tailings contain 1.25~1.5% copper. Both tailings have rare metals. [next]
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 was 20 days and the leaching results are listed in the table below.
3 Copper recovery After the adsorption of rare metals, the tail liquid contains about 2~1.5 (g/L) of copper, and the copper is recovered by sponge or copper by displacement 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 pH of the solution is about 1.5 and the concentration of copper is 2~4 (g/L), the iron consumption ratio is 2~2.5 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 6 hours under the condition of temperature >20 °C. D. Discharge the tail immediately after replacement and adjust the Fe in the tail liquid. The 2+ concentration and acidity are returned to the bacterial culture solution.
4 Main technical and economic indicators The total recovery rate of rare metals is 75~80%, and the total recovery rate of copper is 70~75% (outlet rate is 75~80%, precipitation rate is 90~95%). Sponge copper contains 60~65% copper. The consumption of sulfuric acid per ton of mineral material is 40~45, kg. The cost per ton of copper consumed by 2.5 tons of copper is 2,000 yuan per ton of copper.
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