Method for enriching cobalt from nickel-cobalt slag

Abstract

The invention relates to the technical field of zinc hydrometallurgy, and aims to provide a method for enriching cobalt from nickel-cobalt slag, which comprises the following steps: adjusting and optimizing a nickel-cobalt slag leaching operation process flow, carrying out primary leaching operation on the nickel-cobalt slag by using an electrolytic waste liquid, recovering zinc metal in the nickel-cobalt slag, and carrying out oxidation stockpiling on the leaching slag, so as to obtain the cobalt from the nickel-cobalt slag. And sulfuric acid is used again for secondary leaching operation, and potassium permanganate, sodium persulfate and blown zinc powder are used for iron removal, cobalt removal and cadmium removal operation, so that comprehensive recovery of iron slag, high-cobalt slag and cadmium cotton is achieved. According to the method for enriching cobalt in the nickel-cobalt slag, the problem that the zinc metal recovery rate is low is solved, meanwhile, slag products such as iron slag, high-cobalt slag and cadmium cotton are produced and can be sold or subjected to crude cadmium recovery operation, and extra economic benefits are generated.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgy of zinc, and in particular relates to a method for enriching cobalt from nickel-cobalt slag. Background Art

[0002] The supernatant liquid in the leaching of the wet zinc smelting system contains impurity elements such as copper, cadmium, nickel, and cobalt. These impurity elements are extremely harmful to the electrolysis process of zinc. Therefore, the purpose of the purification system is to remove these impurities. Usually, the purification system adopts a three-stage purification method. In the first stage of purification, blown zinc powder is added to the low-temperature supernatant liquid to replace copper and cadmium, and copper-cadmium slag is produced. In the second stage of purification, alloy zinc powder is added to the high-temperature supernatant liquid to replace cobalt and nickel, and nickel-cobalt slag is produced. At the same time, residual cadmium is removed in the third stage. The nickel-cobalt slag produced by the second-stage purification contains a high level of zinc, and heavy metal recovery operations are required to recover the zinc metal in the nickel-cobalt slag and replenish the amount of zinc metal in the purification system. During the operation, sulfuric acid needs to be added to the nickel-cobalt slag ball mill slurry for leaching. The zinc metal in the nickel-cobalt slag is leached into the liquid by acid leaching. However, in the actual operation process, a large amount of cobalt metal is leached into the liquid. When the liquid returns to the purification system, it causes great operating pressure and cost pressure on the purification system. At the same time, the various slag products in the heavy metal recovery process must be processed through a volatilization kiln, which greatly increases the cost pressure of the enterprise. Summary of the invention

[0003] The object of the present invention is to provide a method for enriching cobalt from nickel-cobalt slag to solve the problems raised in the above background technology.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A method for enriching cobalt from nickel-cobalt slag comprises the following steps:

[0006] 1) Ball milling:

[0007] The nickel-cobalt slag is ball-milled to control the liquid-solid ratio to 3:1, and the particle size after ball-milling is controlled to be 200-120 meshes;

[0008] 2) One-time leaching:

[0009] Adding electrolytic waste liquid to the ore pulp in step 1) for leaching, wherein the mass ratio of electrolytic waste liquid to ore pulp is 2 to 2.5:1;

[0010] 3) Secondary ball milling

[0011] After the first waste liquid leaching operation, the obtained leached residue is transported to the slag yard for storage and oxidation. After the waste liquid leaching residue is fully oxidized, it is ball milled again, and the liquid-solid ratio is controlled to 3:1. The particle size after ball milling is controlled to be 200-120 meshes;

[0012] 4) Secondary leaching:

[0013] The pulp after the secondary ball milling is added with sulfuric acid for leaching, and sulfuric acid is added slowly and continuously to adjust the pulp pH to 3.0. After stirring until the pH reaches 5.0, the pulp is taken out and slowly poured out to observe the slag content in the liquid. Sulfuric acid is slowly added in small amounts again to repeat the above steps until there is no obvious slag in the pulp. After adjusting the pH to 5.0, the reaction is stirred for 4 hours, and the filter is pressed. The filtrate is sent to the iron removal tank for iron removal;

[0014] 5) Iron removal operation:

[0015] The secondary leaching filtrate is sent to the iron removal tank, heated to 80°C, and potassium permanganate is added for iron removal. The addition is carried out twice, stirred for 30 minutes after the addition, and then the liquid pH value is sampled for testing. After the slurry sodium hydroxide liquid is added to adjust the pH to 5.0, the remaining potassium permanganate is added again after stirring for 20 minutes, and the liquid pH value is sampled for testing after stirring for 30 minutes. After the slurry sodium hydroxide liquid is added again to adjust the pH to 5.0, the filtrate is filtered after stirring for 20 minutes, and the filtrate is sent to the cobalt removal tank for cobalt removal;

[0016] 6) Cobalt removal operation:

[0017] The iron removal filtrate is sent to the cobalt removal tank, heated to 80°C, and sodium persulfate is added for cobalt removal. It is added in 5 to 6 times, stirred for reaction for 50 minutes, and then the liquid pH value is sampled and tested. After adding the slurried sodium hydroxide liquid to adjust the pH to 5.0, sodium persulfate is added again after stirring for 20 minutes, and then the liquid pH value is sampled and tested after 50 minutes of stirring. After adding the slurried sodium hydroxide liquid to adjust the pH to 5.0, this operation is repeated after stirring for 20 minutes until the addition of sodium persulfate is completed. Finally, the pH is adjusted to 5.0 and then filtered. The filter residue enters the slurry tank for cobalt residue water washing, and the filtrate is subjected to cadmium removal.

[0018] 7) Cobalt slag washing

[0019] After the cobalt-removing filter residue is added to the slurry tank, a large amount of clean water is added for washing. The liquid-solid ratio is controlled at 3 to 4:1. After the temperature is raised to 50°C, filter press is performed to obtain the enriched high-cobalt slag.

[0020] In the step 2), the electrolytic waste liquid is first slowly added until the pH of the slurry is 2.5-3.0, then the addition of the electrolytic waste liquid is stopped, and then the pressure filtration is performed after the pH becomes 4.5-5.0 through stirring by a reducer.

[0021] In the step 5), the amount of potassium permanganate added is calculated as follows: amount of potassium permanganate added (kg) = V × (CFe × 0.98) / 1000, where V is the volume of the leached liquid (m 3 ), CFe——iron concentration of leachate (mg / L).

[0022] In the step 6), the amount of sodium persulfate added is calculated as follows: sodium persulfate dosage (kg) = V × CCo × (10-20), where V is the liquid volume of the cobalt removal reaction tank (m 3 ), CCo——cobalt content in the solution before cobalt removal (g / L).

[0023] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0024] 1) The present invention adjusts and optimizes the nickel-cobalt slag leaching process, performs a primary leaching operation on the nickel-cobalt slag using electrolytic waste liquid, recovers zinc metal in the nickel-cobalt slag, oxidizes and stores the leached slag, performs a secondary leaching operation using sulfuric acid, and removes iron, cobalt and cadmium by using potassium permanganate, sodium persulfate and blown zinc powder, thereby achieving comprehensive recovery of iron slag, high-cobalt slag and cadmium cotton;

[0025] 2) The present invention solves the problem of low zinc metal recovery rate by adopting a method for enriching cobalt in nickel-cobalt slag, and simultaneously produces slag products such as iron slag, high-cobalt slag, and cadmium cotton, which can be sold or used for crude cadmium recovery operations, thereby generating additional economic benefits. Through actual production practice, a total of 154.63 tons of high-cobalt slag was produced through cobalt metal enrichment operations, with an average cobalt content of 16.55%, a maximum cobalt content of 31.81%, and a cobalt metal content of 5.63 tons. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a flow chart of an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Example

[0030] like Figure 1 As shown, the present invention provides a method for enriching cobalt from nickel-cobalt slag, comprising the following steps:

[0031] (1) Ball milling:

[0032] The nickel-cobalt slag is ball-milled to control the liquid-solid ratio to 3:1, and the particle size after ball-milling is controlled to be around 200-120 meshes.

[0033] (2) One-time leaching:

[0034] Electrolytic waste liquid is added to the slurry for leaching, the mass ratio of electrolytic waste liquid to slurry is 2-2.5:1, and the electrolytic waste liquid is slowly added to the slurry until the pH value is 2.5-3.0, and then the addition of electrolytic waste liquid is stopped. The slurry is stirred by a reducer and then filtered after the pH value becomes 4.5-5.0.

[0035] (3) Secondary ball milling

[0036] After a waste liquid leaching operation, the obtained leaching residue is transported to the slag yard for storage and oxidation. After the waste liquid leaching residue is fully oxidized (the leaching residue turns white in color), it is ball milled again to control the liquid-solid ratio to 3:1. After ball milling, the particle size is controlled at about 200-120 mesh.

[0037] (4) Secondary leaching:

[0038] Add sulfuric acid to the pulp after the second ball milling for leaching. Sulfuric acid is added slowly and continuously to adjust the pH of the pulp to 3.0 (not exceeding 3.0). After stirring the pH to 5.0, take the pulp and slowly pour it out to observe the slag content in the liquid. Sulfuric acid is slowly added in small amounts again to repeat the above steps until there is no obvious slag in the pulp and the pH is adjusted to 5.0. Stir the reaction for 4 hours, perform filter press, and send the filtrate to the iron removal tank for iron removal.

[0039] (5) Iron removal operation:

[0040] The secondary leaching filtrate is sent to the iron removal tank, heated to 80°C, and potassium permanganate is added for iron removal. The amount of potassium permanganate added is calculated according to (amount of potassium permanganate added (kg) = V × (CFe × 0.98) / 1000, where V is the volume of the leaching liquid (m 3 ), CFe——iron concentration of leachate (mg / L), added in two times, stirred for 30 minutes after adding, sampled and tested the liquid pH value, added slurry sodium hydroxide liquid to adjust the pH to 5.0, stirred for 20 minutes, added the remaining potassium permanganate again, stirred for 30 minutes, sampled and tested the liquid pH value, added slurry sodium hydroxide liquid again to adjust the pH to 5.0, stirred for 20 minutes and filtered, and the filtrate was sent to the cobalt removal tank for cobalt removal.

[0041] (6) Cobalt removal operation:

[0042] The iron removal filtrate is sent to the cobalt removal tank, heated to 80°C, and sodium persulfate is added for cobalt removal. The amount of sodium persulfate added is calculated according to (sodium persulfate dosage (kg) = V × CCo × (10-20), where V is the liquid volume of the cobalt removal reaction tank (m 3 ), CCo——cobalt content of the liquid before cobalt removal (g / L), added in 5 to 6 times, stirred and reacted for 50 minutes, sampled and tested the liquid pH value, added slurried sodium hydroxide liquid to adjust the pH to 5.0, stirred for 20 minutes and added sodium persulfate again, stirred and reacted for 50 minutes, sampled and tested the liquid pH value, added slurried sodium hydroxide liquid to adjust the pH to 5.0, stirred for 20 minutes and repeated this operation until the addition of sodium persulfate was completed, and finally adjusted the pH to 5.0 and filtered, the filter residue entered the slurry tank for cobalt slag washing, and the filtrate was used for cadmium removal.

[0043] (7) Cobalt slag washing

[0044] After the cobalt-removing filter residue is added to the slurry tank, a large amount of clean water is added for washing. The liquid-solid ratio is controlled at 3 to 4:1. After the temperature is raised to 50°C, filter press is performed to obtain the enriched high-cobalt slag.

[0045] Actual work cases:

[0046] The treatment objects are the nickel-cobalt slag and electrolytic waste liquid produced by the purification system of this unit. The composition table of electrolytic waste liquid, nickel-cobalt slag and high-cobalt slag is as follows:

[0047] 1. Nickel-cobalt slag

[0048] Name / Element Zn <![CDATA[H2O]]> Co Pb Nickel-cobalt slag (area 1) 58.63 20.03 0.34 1.02 Nickel-cobalt slag (Zone 2) 68.84 13.79 0.15 0.51

[0049] 2. Electrolytic waste liquid

[0050] Name / Element Zn(g / L) <![CDATA[H2SO4(g / L)]]> Electrolytic waste liquid 62.35 180.59

[0051] 3. High cobalt slag

[0052] Name / Element Zn(%) Co(%) H2O(%) High cobalt slag 25.63 23 64.2 High cobalt slag 22.36 25.94 69.69

Claims

1. A method for enriching cobalt from nickel-cobalt slag, characterized in that: The following steps are involved: 1) Ball milling: The nickel-cobalt slag is ball-milled to control the liquid-solid ratio to 3:1, and the particle size after ball-milling is controlled to be 200-120 meshes; 2) One-time leaching: Adding electrolytic waste liquid to the ore pulp in step 1) for leaching, wherein the mass ratio of electrolytic waste liquid to ore pulp is 2 to 2.5:1; 3) Secondary ball milling After the first waste liquid leaching operation, the obtained leached residue is transported to the slag yard for storage and oxidation. After the waste liquid leaching residue is fully oxidized, it is ball milled again, and the liquid-solid ratio is controlled to 3:

1. The particle size after ball milling is controlled to be 200-120 meshes; 4) Secondary leaching: The pulp after the secondary ball milling is added with sulfuric acid for leaching, and sulfuric acid is added slowly and continuously to adjust the pulp pH to 3.

0. After stirring until the pH reaches 5.0, the pulp is taken out and slowly poured out to observe the slag content in the liquid. Sulfuric acid is slowly added in small amounts again to repeat the above steps until there is no obvious slag in the pulp. After adjusting the pH to 5.0, the reaction is stirred for 4 hours, and the filter is pressed. The filtrate is sent to the iron removal tank for iron removal; 5) Iron removal operation: The secondary leaching filtrate is sent to the iron removal tank, heated to 80°C, and potassium permanganate is added for iron removal. The addition is carried out twice, stirred for 30 minutes after the addition, and then the liquid pH value is sampled for testing. After the slurry sodium hydroxide liquid is added to adjust the pH to 5.0, the remaining potassium permanganate is added again after stirring for 20 minutes, and the liquid pH value is sampled for testing after stirring for 30 minutes. After the slurry sodium hydroxide liquid is added again to adjust the pH to 5.0, the filtrate is filtered after stirring for 20 minutes, and the filtrate is sent to the cobalt removal tank for cobalt removal; 6) Cobalt removal operation: The iron removal filtrate is sent to the cobalt removal tank, heated to 80°C, and sodium persulfate is added for cobalt removal. It is added in 5 to 6 times, stirred for reaction for 50 minutes, and then the liquid pH value is sampled and tested. After adding the slurried sodium hydroxide liquid to adjust the pH to 5.0, sodium persulfate is added again after stirring for 20 minutes, and then the liquid pH value is sampled and tested after 50 minutes of stirring. After adding the slurried sodium hydroxide liquid to adjust the pH to 5.0, this operation is repeated after stirring for 20 minutes until the addition of sodium persulfate is completed. Finally, the pH is adjusted to 5.0 and then filtered. The filter residue enters the slurry tank for cobalt residue water washing, and the filtrate is subjected to cadmium removal. 7) Cobalt slag washing After the cobalt-removing filter residue is added to the slurry tank, a large amount of clean water is added for washing. The liquid-solid ratio is controlled at 3 to 4:

1. After the temperature is raised to 50°C, filter press is performed to obtain the enriched high-cobalt slag.

2. A method for enriching cobalt from nickel-cobalt slag according to claim 1, characterized in that: In the step 2), the electrolytic waste liquid is first slowly added until the pH of the slurry is 2.5-3.0, then the addition of the electrolytic waste liquid is stopped, and then the pressure filtration is performed after the pH becomes 4.5-5.0 after stirring with a reducer.

3. A method for enriching cobalt from nickel-cobalt slag according to claim 1, characterized in that: In the step 5), the amount of potassium permanganate added is calculated as follows: amount of potassium permanganate added (kg) = V × (CFe × 0.98) / 1000, where V is the volume of the leached liquid (m 3 ), CFe——iron concentration of leachate (mg / L).

4. A method for enriching cobalt from nickel-cobalt slag according to claim 1, characterized in that: In the step 6), the amount of sodium persulfate added is calculated as follows: sodium persulfate dosage (kg) = V × CCo × (10-20), where V is the liquid volume of the cobalt removal reaction tank (m 3 ), CCo——cobalt content in the solution before cobalt removal (g / L).

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