Study on Acid Leaching of Low Grade Primary Copper Sulfide Ore by Activated Carbon
Currently, wet copper smelting technology has become the preferred treatment process of secondary copper sulphide ores and low grade copper oxide ore, but for low-grade primary copper sulphide ores, leaching due to a long period, the copper leaching rate is also difficult in It is used in industrial production. In order to enhance the effect of leaching chalcopyrite, respectively, from microbiology, electrochemistry, metallurgy science and other point of view, to explore a variety of enhanced chalcopyrite leaching process in which chalcopyrite leaching studies to improve the rate of electrochemical principle Get much attention. In recent years, there have been many researches on catalytic oxidation or composite catalysts at home and abroad. From the perspective of microbiology and electrochemistry, the research on the leaching of low-grade primary copper sulfide ore by Yongjia, Ag + or Fe 2+ has been made. effect. The addition of activated carbon, Ag + or Fe 2+ catalyst can greatly accelerate the bacterial copper leaching rate of low-grade primary copper sulfide ore and increase the copper leaching rate, but the presence of bacteria will also affect the catalytic effect of the catalyst. Therefore, in order to find out whether it is necessary to add bacteria under the conditions of adding activated carbon, Ag + or Fe 2+ , the acid leaching behavior of activated carbon catalyzed Yongping low-grade primary copper sulfide ore was studied according to electrochemical principle.
First, the test part
(1) Test materials
The test ore sample was taken from Yongping Copper Mine. The chemical composition is (%): SiO 2 40.9, ∑Fe 14.12, Al 2 O 3 6.68, CaO 9.97, MgO1.64, K 2 O 1.58, Na 2 O 0.27, P 2 O 5 0.05, Cu 0.87, S 13.00; The main mineral component (%): 12.26 pyrite, pyrrhotite 0.76, 0.08 magnetite, garnet 1.21, 0.56 calcite, a small amount of chalcopyrite. In the ore, free copper oxide accounts for 1.33%, combined with copper oxide accounts for 0.35%, secondary copper sulfide accounts for 1.85%, and primary copper sulfide accounts for 95%.
(2) Test methods
The shake flask test was carried out in a gas bath constant temperature shaking box at 30 ° C and 130 r/min. During the leaching process, the changes of Fe 2+ , Fe 3+ , pH, Eh, Cu 2+ , etc. of the solution were monitored; the volume of the solution reduced by evaporation was supplemented with distilled water to ensure that the total volume of the solution (ie, 100 mL) was unchanged.
(3) Analytical methods
The mass concentrations of Fe 2+ and Fe 3+ in the solution were determined by EDTA titration; pH and Eh were determined by a pH meter; Cu 2+ mass concentration was measured by a WFX-120 atomic absorption spectrophotometer.
Second, the results and discussion
Add 25 g of acidified ore powder with a particle size of -0.1 mm to a 250 mL Erlenmeyer flask, and add 0, 0.05, 0.2, 0.3, 0.5, 1.0 g of activated carbon respectively (the mass concentration of activated carbon is 0, 0.5, 2.0 respectively). , 3.0, 5.0 and 10.0 g L), uniformly mixed and placed for 1 d, then 100 mL of water was added, and the initial pH of the solution was adjusted to 1.20 with 1+1 sulfuric acid. During the leaching process, the pH was controlled at 1.50, and the effect of the concentration of activated carbon on the catalytic effect was investigated.
(1) Effect of activated carbon mass concentration on copper leaching
Figure 1 shows the experimental results of the effect of mass concentration of activated carbon on copper leaching. It can be seen that the addition of activated carbon can greatly accelerate the acid leaching rate of low-grade primary copper sulfide ore and increase the copper leaching rate, and the copper leaching rate and leaching rate also increase with the increase of the mass concentration of activated carbon. There is a consistent trend in the presence of bacteria. However, under aseptic conditions, the copper leaching rate and leaching rate decreased after the concentration of activated carbon exceeded 5.0g/L. Under the condition of bacteria, the copper leaching rate and leaching rate began to decrease after the mass concentration of activated carbon exceeded 2.0g/L. Therefore, under acidic aseptic conditions, the mass concentration of activated carbon is 5.0g/L, which is most beneficial for copper leaching. After immersion for 240h, the copper leaching rate increases to 83%, which is nearly 80% higher than that without adding activated carbon.
Fig.1 Effect of mass concentration of activated carbon on copper leaching rate
(II) Effect of mass concentration of activated carbon on iron leaching
Figures 2 and 3 show the experimental results of the effect of mass concentration of activated carbon on iron leaching.
Figure 2 Effect of mass concentration of activated carbon on iron leaching rate
Figure 3 Effect of mass concentration of activated carbon on iron leaching rate
It can be seen from Fig. 2 and 3 that the addition of activated carbon in the initial stage of acid leaching accelerates the leaching of iron in the ore and the oxidation rate of Fe 2+ in the solution, and the iron leaching rate and Fe 2+ oxidation rate continue with the increase of the initial activated carbon concentration. Increase. After a period of reaction, the iron leaching rate and leaching rate decreased with the increase of the mass concentration of activated carbon. When the mass concentration of activated carbon exceeded 5.0g/L, the iron leaching rate decreased rapidly. The oxidation of ferrous iron is greatly affected by the mass concentration of activated carbon. The absence of activated carbon or excessive activated carbon is not conducive to the oxidation of ferrous iron. Therefore, under sterile acidic conditions, the addition of 5.0g/L activated carbon is beneficial to the leaching and inhibition of iron. Oxidation of valence iron.
(III) Effect of activated carbon on Eh of leachate
Figure 4 shows the results of the effect of the mass concentration of activated carbon on the Eh of the leachate. Adding activated carbon can reduce the Eh value of the leachate, and as the mass concentration of activated carbon increases, Eh decreases continuously. This is because the activated carbon suppresses the oxidation of ferrous iron in the leachate, and the inhibitory effect is continuously enhanced as the concentration of the activated carbon increases.
Figure 4 Effect of mass concentration of activated carbon on leachate Eh
It can also be seen from Figures 1 to 4 that when the divalent iron maintains the Eh value of the leachate below 640 mV, the copper leaching speed is fast; on the contrary, the copper leaching speed is slowed down. This is because, as a result of the galvanic effect, activated carbon is a good conductor of electricity, which can adsorb on the surface of chalcopyrite and form a primary battery with chalcopyrite.
Under high oxidation-reduction potential, the dissolution reaction of chalcopyrite is relatively poor. Because of the oxidative leaching process of chalcopyrite, a non-conductive and dense elemental sulfur film forms on the surface, forming a diffusion barrier, making electron transfer difficult and hindering. Dissolution of CuFeS 2 . However, in the presence of low redox potential and presence of copper ions, the dissolution rate of chalcopyrite is very fast, because the secondary chalcopyrite produced by the reduction of chalcopyrite is easily oxidized to Cu 2+ and on the surface of chalcopyrite. A non-conductive dense elemental sulfur film is not produced.
In the acid leaching process, the addition of activated carbon can make the ore become the main leaching at the low oxidation-reduction potential, and become the secondary leaching at the high oxidation-reduction potential, indicating that the low oxidation-reduction potential is more than the high oxidation-reduction potential in the presence of activated carbon. Conducive to copper leaching, but too low oxidation-reduction potential is not good for copper leaching.
Third, the conclusion
(1) In the aseptic acid leaching process of low-grade primary copper sulphide ore, the addition of activated carbon can greatly accelerate the leaching rate of copper and increase the leaching rate of copper. Among them, the concentration of activated carbon of 5.0g/L is most beneficial to the leaching of copper, leaching 240 After h, the copper leaching rate can reach 83%, which is nearly 80% higher than that without adding activated carbon, because the primary battery reaction between activated carbon and chalcopyrite promotes the dissolution of chalcopyrite.
(2) During the aseptic acid leaching process, when there is activated carbon, the low redox potential (about 640 mV) is more favorable for copper leaching than the high redox potential.
cleaning machine
ZHEJIANG BOTUOLINI MECHANICAL CO.,LTD , http://www.botuopump.com