Study on Pressure Leaching Process of Complex Cobalt Sulfide Ore
The main features of cobalt ore resources in China is poor, less high-grade ore, the lack of a single cobalt deposits, most of the symbiotic or associated copper, nickel, iron ore. Extracting the cobalt from the main weight of the gold-nickel or copper metal smelting slag system cobalt, about 35% of total cobalt, other extraction of cobalt from the raw material inlet and the waste about 65 percent of the total cobalt. The complex cobalt sulfide ore in some places in China contains elements such as nickel, copper, iron and arsenic . Cobalt is mainly composed of cobalt and cobalt, and nickel is mainly composed of nickel-cobalt ore. Cannot enter by fire method
Effective separation. In this Paper, the pressurized wet leaching process is used to make cobalt, nickel and copper enter the solution, and iron and arsenic form stable iron arsenate into the leaching slag.
First, experimental research
(1) Test materials
Materials used for the test of a complicated cobalt sulfide ores, the sulfide ore mainly chalcopyrite, pyrite, arsenopyrite, followed as sphalerite, tetrahedrite, cobaltite, small amount of nickel cobaltite . The main components of the ore are (%): Co2.40, Ni0.78, Cu2.10, Fe11.30, S8.45, Zn0.98, As11.99. After the fine ore is finely ground, more than 90% is less than 0.074 mm. The reagents used in the test, such as sulfuric acid, are all analytically pure. The water used in the preparation solution was deionized water.
(2) Test device
The pressurized oxidation test was carried out in a GSA-2L vertical titanium -lined autoclave. Oxygen is 98% industrial pure oxygen.
The ore, water, sulfuric acid and additives are mixed in a certain proportion, added to the pressure vessel, sealed and heated, and a small amount of oxygen is introduced. When the temperature rises to 85-95 ° C, open the vent valve to vent. After the set temperature is reached, oxygen is introduced and the total pressure is adjusted to the test value, and the timing is started. The temperature and pressure of the reaction are strictly controlled during the test. After the completion of the reaction, the cooling water was passed through to cool the kettle to 60 ° C, and the kettle was opened, and the material was separated by filtration using a rotary vane vacuum pump. The leaching residue is rinsed with water. The leachate and the leach residue were separately sent for analysis.
(3) Test principle
According to the original ore composition, the pressure leaching test process mainly performs the following reactions:
CoAsS+13/4O 2 +3/2H 2 O=CoSO 4 +H 3 AsO 4
CuFeS 2 +H 2 SO 4 +5/2O 2 =CuSO 4åFeSO 4 +H 2 O+S
4FeSO 4 +O 2 +2H 2 SO 4 =2Fe 2 (SO 4 ) 3 +2H 2 O
Fe 3 + +H 3 AsO 4 =FeAsO 4 +3H +
2ZnS+2H 2 SO 4 +O 2 =2ZnSO 4 +2H 2 O+S
Second, test methods and results
(1) Influence of reaction temperature
Test conditions: L/S = 5/1, sulfuric acid concentration 0.82 mol/L, additive A 0.5 g, total pressure 0.85 MPa, reaction time 2.0 h. The test results are shown in Figure 1.
Figure 1 Effect of leaching temperature on metal leaching rate
It can be seen from Fig. 1 that the high temperature is favorable for the leaching of copper, nickel and diamond, and the leaching rate of copper, nickel and diamond is greater than 90% at 150 °C. The leaching rate of iron is proportional to temperature. However, iron was hydrolyzed and precipitated after 160 °C. The leaching rate of arsenic decreases with increasing temperature. However, the initial acid concentration is higher, resulting in an arsenic concentration in the leachate above 0.3 g/L, thus reducing the initial sulfuric acid concentration.
(two) the impact of leaching time
Test conditions: L/S = 5/1, sulfuric acidity 0.82 mol/L, additive A 0.5 g, reaction temperature 60 ° C, total pressure 0.85 MPa. The test results are shown in Figure 2.
Figure 2 Effect of leaching time on metal leaching rate
It can be seen from Fig. 2 that the leaching rates of cobalt, nickel, copper and iron increase with the reaction time. After 1.5 h of reaction, the leaching rates of cobalt, nickel and copper were all above 90%, while arsenic and most of the iron were inhibited in the slag.
(III) Influence of initial sulfuric acid concentration
Test conditions: L / S = 5 / 1, additive A 0.5g; reaction temperature 160 ° C, total pressure 0.85MPa, reaction time 1.5h. The test results are shown in Figure 3.
Figure 3 Effect of initial acid concentration on metal leaching rate
The results show that sulfuric acid is beneficial to the leaching of cobalt, nickel and copper. When the initial acidity is 0.51 mol/L, the leaching rates of cobalt, nickel and copper are all above 90%, but the content of iron and arsenic in the leachate is high. When the initial acidity is 0.41 mol/L, the content of iron and arsenic in the immersion liquid is low, but the leaching rate of cobalt, nickel and copper is low.
(4) The influence of oxygen partial pressure
Test conditions: L / S = 5 / 1, sulfuric acid degree 0.4 mol / L, additive A 0.5g, reaction temperature 150 ° C, reaction time 1.5h. The test results are shown in Figure 4.
Figure 4 Effect of oxygen partial pressure on metal leaching rate
The results show that the partial pressure of oxygen increases, and the leaching rate of cobalt-nickel-copper increases, but the change is small. At the same time, the partial pressure of oxygen on the leaching of iron and arsenic is not loud. The partial pressure of oxygen may be 0.3 MPa or less.
(5) Influence of slurry-solid ratio
Test conditions: initial acidity of sulfuric acid 0.41 mol / L, additive A 0.5g, reaction temperature 160 ° C, total pressure 0.85MPa, reaction time 1.5h. The test results are shown in Figure 5.
Fig. 5 Effect of slurry-solid ratio on metal leaching rate
The results show that the liquid-solid ratio has little effect on the leaching of cobalt-nickel-copper, but has a great influence on iron. When the liquid-solid ratio is low, the iron content in the leachate is low. Therefore, the liquid-solid ratio is preferably 4/1.
(6) Comprehensive test
Test conditions: L/S=4/1, initial acidity of sulfuric acid 0.61 mol/L, additive A0.5 g, reaction temperature 160 ° C, total pressure 0.85 MPa, reaction time 1.5 h. The test results show that the leaching rate of cobalt reaches over 93%, and the leaching rate of nickel copper is greater than 90%. By analyzing the XRD diffraction pattern of the leaching slag, iron arsenate, quartz, and calcium sulfate are abundantly present in the slag. It indicates that the valuable metals are almost completely leached after leaching, and iron and arsenic enter the slag phase. The results of this test are reproducible.
Third, the conclusion
At low temperature and low pressure, additives are added. The leaching rate of cobalt in complex cobalt sulfide is greater than 92%, and the leaching rate of copper and nickel is greater than 90%. At the same time, arsenic and iron form stable iron arsenate into human leaching residue.
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