Process technology for extracting cobalt from cobalt oxide ore
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At present, the production of cobalt is basically based on cobalt earth ore, cobalt-sulfur concentrate, copper-copper- nickel slag, arsenic- cobalt ore. The average grade of proven cobalt ore resources is only 0.02%, and the recovery rate is low, the process is complicated, and the production cost is high.
First, the nature of the ore
The cobalt ore used in the test was an African Congo-oxidized hydrocobalt ore, which was grayish black with a density of 2.780 t/m 3 . The chemical analysis results are shown in Table 1. The water-cobalt ore is a complex oxide and hydroxide with different impurity components and crystallinity. The X-ray diffraction results indicate that it may be a trivalent and divalent monohydrate variant with unstable components such as water, cobalt and copper. Mineral (2Co 2 O 3 Â·CuOÂ·6H 2 O), copper hydrocobalt (2Co 2 O 3 Â·CuOÂ·3H 2 O), etc.
Table 1 Results of chemical analysis of hydrous cobalt ore
Second, instruments, reagents and process
The instruments used in the test are KS-II Kang's oscillator, 78HW-1 constant temperature magnetic stirrer, LD2001 electronic scale, JJ-2 type booster electric mixer, 2XZ-0.5 rotary vane vacuum pump, F97-A ore crusher, liquid separation funnel.
The reagents used in the test were industrial grade sodium thiosulfate, sodium carbonate, sodium chlorate, P204, P507, sulfuric acid, chemically pure sodium fluoride, ammonium oxalate, and analyzed pure ammonia water.
The test process flow is shown in Figure 1.
Third, the results and discussion
The low-oxide oxide of cobalt is easily dissolved in a dilute sulfuric acid solution to form soluble CoSO4, and the high-valent oxide must be dissolved in concentrated sulfuric acid. The reaction formula is:
CoO+H 2 SO 4 (lean) = CoSO 4 +H 2 O,
Co 2 O 3 + 2H 2 SO 4 (concentrated) = 2CoSO 4 + 2H 2 O + 1/2O 2 ,
CoOÂ·SiO 2 +H 2 SO 4 (lean)=CoSO 4 +H 2 SiO 3 ,
CoOÂ·Fe 2 O 3 +4H 2 SO 4 (lean) = CoSO 4 +Fe 2 (SO 4 ) 3 +4H 2 O.
1, a section of leaching
The hydrocobalt ore was ground and slurried and leached with 1 mol/L H2SO4 solution. The effect of ore particle size, leaching time and leaching temperature on cobalt leaching rate was mainly investigated. The test results are shown in Tables 2 to 4.
Table 2 Effect of ore particle size on cobalt leaching rate
The leaching time was 12 h; the leaching temperature was 90 Â°C.
Table 3 Effect of leaching time on cobalt leaching rate
The ore has a particle size of -200 mesh and a leaching temperature of 90 Â°C.
Table 4 Effect of leaching temperature on cobalt leaching rate
Ore size - 200 mesh, leaching time 12h.
It can be seen from Tables 2 to 4 that the finer the ore particle size, the higher the leaching temperature, the longer the holding time, and the higher the cobalt leaching rate. Considering comprehensively, a section of leaching is preferably carried out with an ore particle size of 200 mesh or less, a holding time of 12 hours, and a temperature of 90 Â°C.
2, two-stage leaching
Take a section of leaching slag, adjust the slurry according to the liquid solid mass ratio of 2:1, and immerse it with 4mol/L H 2 SO 4 solution according to the liquid solid mass ratio of 4:1, the temperature is above 95 Â°C, keep warm for a certain time, check the ore particle size, The effect of holding time on cobalt leaching rate. The test results are shown in Tables 5 and 6. It can be seen that the ore particle size is reduced, the holding time is prolonged, and the cobalt leaching rate is increased. Considering comprehensively, the ore particle size is below 200 mesh and the holding time is 24 h.
Table 5 Effect of ore particle size on cobalt leaching rate
Keep warm for 24h; temperature above 95 Â°C.
Table 6 Effect of holding time on cobalt leaching rate
(2) Purification of leachate
With sulfuric acid leaching through two stages, most of the cobalt in the ore enters the solution, while other coexisting elements also enter the solution. The presence of impurity elements has a large effect on the recovery of cobalt or cobalt compounds and needs to be removed beforehand. The composition of the leachate obtained under the optimum conditions is shown in Table 7.
Table 7 Leachate composition stage g/L
(3) Removal of iron
Iron is removed by the yellow sodium iron sputum method. Yellow sodium iron strontium [Na 2 Fe 6 (SO 4 ) 4 (OH) 12 ] is a pale yellow crystal and is a salt-based sulfate having good filtration performance and good washing performance. The total iron removal reaction formula is:
3Fe 2 (SO 4 ) 3 +6H 2 O+5Na 2 CO 3 =Na 2 Fe 6 (SO 4 ) 4 (OH) 12 â†“+5Na 2 SO 4 +6CO 2
1000 mL of the above leaching solution was taken, and the pH was adjusted for the test. The results are shown in Table 8. It can be seen that the endpoint pH has a great influence on the formation of iron shovel. The pH is in the range of 4.0 to 4.5, the iron removal is complete, and the cobalt/iron mass concentration ratio in the solution reaches 18,600.
Table 8 Effect of solution pH on Fe precipitation
(4) Except Ca 2 + , Mg 2 + , Cu 2 +
By using the characteristics of low solubility of fluoride of Ca 2 + and Mg 2 + , the pH of the solution is controlled so that Ca 2 + and Mg 2 + form CaFe 2 and MgFe 2 precipitates, respectively. Na 2 S 2 O 3 reacts with Cu 2 + to form a CuS precipitate, and Co 2 + remains in the solution, thereby achieving separation of Ca 2 + , Mg 2 + , Cu 2 + from Co 2 + and Ni 2 + . The reaction equation is as follows:
MgSO 4 +2NaF=MgFe 2 â†“+Na 2 SO 4 ,
CaSO 4 +2NaF=CaF 2 â†“+Na 2 SO 4 ,
2CuSO 4 +2Na 2 S 2 O 3 +2H 2 O=Cu 2 S+S+2Na 2 SO 4 +2H 2 SO 4 .
For the solution with iron removed, a certain amount of NaF and Na 2 S 2 O 3 were added at a certain temperature to investigate the effect of NaF on the removal of Ca 2 + and Mg 2 + impurities and Na 2 S 2 O 3 to Cu 2 + . The effect of removal. The test results are shown in Tables 9 and 10. It can be seen that at a certain temperature, the amount of NaF and Na 2 S 2 O 3 can be controlled to remove Ca 2 + , Mg 2 + and Cu 2 + in the leachate.
Table 9 Effect of NaF addition on Ca 2 + and Mg 2 + removal
Holding time 4h.
After the solution was adjusted to pH, Na 2 S 2 O 3 was added and incubated at a certain temperature for 30 min.
(5) P204 extraction depth in addition to impurities
The chemically removed solution also contained small amounts of impurities (Table 11) and required deep purification. The solution pH, flow rate, etc. are controlled, and the impurities can be further removed by cascade extraction. The extraction section was calculated to be grade 8 by cascade extraction theory and the wash section was grade 7. Flow ratio: V (organic phase): V (washing liquid) = 8:3:1. The solution pH was 4.5 and the ingredients are shown in Table 12.
Table 11 Solution composition after chemical removal g/L
Table 12 Raffinate components after impurities, g/L
(6) P507 extraction and separation of cobalt and nickel
The raffinate after removal of impurities (see Table 12 for composition) was subjected to cobalt-nickel separation. The pH, flow rate and extraction series were controlled for extraction. Ï(Ni 2 + )=0.056g/L, Ï(Co 2 + )=0.154g/L in the raffinate; Ï(Ni2+)<0.001g/ in the organic phase L, Ï(Co 2 + ) = 0.154 g/L.
The cobalt was back-extracted from the organic phase in a 6-stage manner, and the washing liquid was 2.5 mol/L HCl. The controlled flow ratio was: V (organic phase): V (washing liquid) = 6:1. The composition of the CoCl 2 solution after stripping is shown in Table 13.
Table 13 Composition of CoCl 2 solution after stripping g/L
(7) Precipitation and drying
In the solution after removing impurities, cobalt exists in the form of CoCl 2 , and cobalt oxalate is precipitated by ammonium oxalate precipitation method, and the reaction formula is as follows:
Co 2 + +(NH 4 )2C 2 O 4 =CoC 2 O 4 +2NH 4 -
The cobalt oxalate precipitate contains a certain amount of soluble ions (such as NH 4 + , Na + , SO 4 2 - , Cl - , etc.), and washed with hot water to obtain a refined cobalt oxalate product. The divalent cobalt oxalate is usually pink, hardly soluble in water, slightly soluble in acid, and becomes an anhydrous salt when heated in air. The washed cobalt oxalate is dried in a box furnace at a furnace temperature of 90 to 110 Â° C to control the color of cobalt oxalate to be pink and the moisture is less than 0.65%. The obtained cobalt oxalate product had a bulk density of 0.29 g/cm 3 and the chemical composition is shown in Table 14.
Table 14 Chemical composition stage of cobalt oxalate product %
Fourth, the conclusion
(1) Cobalt oxide type water cobalt is leached by two stages of sulfuric acid. The concentration of Co2+ in the leaching solution is 15-20 g/L, and the cobalt leaching rate is 99%.
(2) The chemical method is used to remove Fe, Ca, Mg and Cu impurities in the solution, and the impurity content can be controlled to meet the requirements.
(3) For the chemically-depleted leachate, the 204-stage extraction is used to further remove the impurities, and the P507 extracts and separates the cobalt and nickel to obtain a qualified CoCl 2 solution.
(4) Cobalt oxalate is precipitated by ammonium oxalate, and dried at a certain temperature after washing to obtain a cobalt oxalate product.
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T Shirt Printer Heat Press Machine could transfer photos, words on cotton, fiber, metal, ceramic, glass and so on, suitable for producing gift, advertisement and so on. It can be able to apply transfers, letters, numbers and images onto T-shirts, garments, bags, mouse mats, jigsaw puzzles, ceramic tiles, plates and other flat surfaced items. The digital timer control is adjustable up to 999 seconds. The heat press machine also features a digital temperature gauge ranging from 0 - 399Â°C (about 750Â°F). Keeping pressing the button "SET" for a while can switch Fahrenheit and Celsius temperature back and forth.The manual open and close handle is easy to operate and can be adjusted with the pressure knob at the rear of the machine. Its industrial strength and durability allows for long-term use, making it a great investment with exceptional value amongst its competitors. The machine is CE certified and come with 2 years free warranty. this is DIY homemade T-Shirt Printer.
T Shirt Printer, Heat Press Machine, T Shirt Printing Machine, T Shirt Sublimation Machine, T-Shirt Making Machine
HARBIN QIAN FAN XI FENG MACHINERY CO.LTD , https://www.waterjetwamit.com