A method for efficiently enriching cobalt in cobalt slag purified from a hydrometallurgical zinc smelting system

Abstract

The present invention relates to a method for efficiently enriching cobalt in purified cobalt slag in a wet zinc smelting system. The main steps of the method include roasting the purified cobalt slag, weakly acidic leaching of roasted sand, and purification of the leachate. First, the purified cobalt slag in the wet zinc smelting system is screened to obtain a raw material with uniform particle size. The pelletized material is then placed in a normal pressure environment for high-temperature roasting. The roasted sand produced after roasting is leached in a sulfuric acid solution of a certain concentration to obtain cobalt-rich slag with a cobalt content of about 15% and a zinc-containing solution. The present invention achieves efficient enrichment of cobalt in the purified cobalt slag in the wet zinc smelting system. The produced zinc liquid can be returned to the zinc electrolysis system to recover zinc, and the cobalt-rich slag can be used as raw material for cobalt smelting and extraction. This achieves efficient enrichment and recovery of low-grade cobalt slag, achieving the purpose of comprehensive recycling and utilization of cobalt-containing secondary resources.

Description

Technical Field

[0001] The invention belongs to the technical field of mineral processing and comprehensive utilization of solid waste, and in particular to a method for efficiently enriching cobalt in cobalt slag purified by a hydrometallurgical zinc smelting system. Background Art

[0002] Purified cobalt slag, an important cobalt-containing secondary resource, primarily contains zinc, cadmium, cobalt, and nickel. Zinc typically accounts for around 40%, while cobalt accounts for only 0.1% to 1%. Several methods for treating purified cobalt slag have been developed. Patent CN201010187773.7 discloses a wet separation and recovery method for zinc and cobalt from purified cobalt slag. This method first screens and crushes the purified cobalt slag from the hydrometallurgical zinc smelting process, then performs staged leaching in a sulfuric acid system. The leached slurry is then separated to remove lead slag. An oxidant is then added to the impurity-removed leachate to separate the Fe and Co elements, yielding a high-cobalt slag concentrate. Patent CN201410037098.8 discloses a multi-stage leaching method for recovering zinc and cobalt from purified cobalt slag. This method employs an acid leaching and water washing process for the first stage of leaching. The concentrated zinc solution then enters a zinc electrowinning workshop to produce electrolytic zinc. The resulting leaching residue is then subjected to a drying-heating acid leaching method for a second leaching step, thereby realizing the recovery of cobalt. Patent CN202111244594.7 discloses that the slurried cobalt-zinc slag is first subjected to an oxidation treatment to convert the cobalt into an insoluble cobalt salt, and the cobalt-containing oxide slag is obtained after separation and washing. The cobalt-containing oxide slag is then subjected to a secondary leaching step to leach out the zinc therein, while the cobalt remains in the slag, and finally a zinc-containing solution and a high-cobalt slag are obtained, thereby realizing the separation and recovery of zinc and cobalt. Although the methods mentioned in the above patents can realize the separation of zinc and cobalt, they all require multi-stage leaching of the cobalt slag and then precipitation of the leachate to remove cobalt to obtain cobalt-rich slag. The process is long and the cobalt is easily dispersed, which is not conducive to the efficient recovery of cobalt. Summary of the Invention

[0003] In view of the current problems such as the enrichment and recovery of cobalt in purified cobalt slag, the present invention provides a process for separating and recovering zinc and cobalt in purified cobalt slag. First, the purified cobalt slag is roasted at normal pressure to control the phase transformation process of zinc and cobalt contents in the purified cobalt slag to form an insoluble cobalt-containing phase. Then, the roasted product is subjected to weak acid leaching in a weakly acidic sulfuric acid solution to achieve the separation of soluble zinc oxide and the insoluble cobalt-containing phase, thereby obtaining high-grade cobalt-rich slag.

[0004] The present invention provides a method for efficiently enriching cobalt in cobalt slag purified from a hydrometallurgical zinc smelting system, which mainly comprises the following steps:

[0005] Step 1: drying the purified cobalt slag and then calcining it at a temperature of 400 to 850° C. for 60 to 180 minutes to obtain a calcined product;

[0006] Step 2: After the roasted product is cooled, it is mixed with a sulfuric acid solution, stirred and leached to obtain a feed solution;

[0007] Step 3: Filter the feed liquid, and return the obtained leachate to the hydrometallurgical zinc leaching liquid purification system for deep purification; the leachate residue obtained by filtration is washed with water and dried to obtain the cobalt-rich residue.

[0008] Furthermore, the purified cobalt slag in step 1 is the cobalt-containing slag produced by treating the leachate with zinc powder replacement method during the hydrometallurgical zinc smelting process, including but not limited to zinc powder replacement methods such as arsenic salts, antimony salts, and zinc-lead alloy powder.

[0009] Furthermore, the main components of the purified cobalt slag in step 1 are unreacted zinc powder, a composite compound of zinc hydroxide and sulfate, and a small amount of cobalt compound, wherein the mass percentage of cobalt element is 0.2 to 1.5 wt.%.

[0010] Furthermore, the equipment used for the roasting in step 1 includes but is not limited to roasting rotary kilns, boiling furnaces and other equipment that can heat the purified cobalt slag.

[0011] Furthermore, the pH of the sulfuric acid solution in step 2 is 3.0 to 5.5.

[0012] Furthermore, the stirring leaching conditions in step 2 are: leaching temperature of 70-90° C., slurry concentration of 10-40%, leaching time of 30-60 min, mechanical stirring during the leaching process, and a stirring speed of 200-500 rpm.

[0013] Furthermore, the hydrometallurgical zinc smelting leachate purification system described in step 3 is an existing industrial hydrometallurgical zinc smelting system, including the steps of zinc sulfide concentrate roasting, acid leaching, leachate purification, electrolysis, etc.

[0014] Furthermore, the purified liquid after the deep purification described in step 3 can be repeatedly returned to step 2 for leaching again.

[0015] Preferably, the calcination conditions in step 1 are: calcination temperature at 500° C. and calcination time for 120 min.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) The method for enriching cobalt by roasting and weak acid leaching of purified cobalt slag provided by the present invention adopts roasting to change the occurrence phases of zinc and cobalt components in the purified cobalt slag, thereby realizing the phase transformation of the cobalt element into an insoluble cobalt-zinc composite oxide, which is beneficial to the weak acid leaching separation of the zinc and cobalt occurrence phases.

[0018] (2) The cobalt enrichment process does not require the use of multi-stage acid leaching, oxidation precipitation and other processes. The cobalt enrichment is achieved by one-step weak acid leaching after roasting, which reduces the series of raw material consumption costs of the conventional multi-stage leaching-precipitation cobalt removal method. The process flow is short and clean, the operation is simple and the cost is low. It is suitable for the cobalt enrichment and recovery of various types of purification slag with low cobalt content.

[0019] (3) The method of cobalt enrichment by roasting purified cobalt slag and weak acid leaching provided by the present invention converts most of the zinc in the purified cobalt slag into easily soluble ZnO during the roasting process, and the cobalt element therein is converted into a metal complex with better stability, thereby ensuring a large degree of zinc dissolution during the leaching process. While improving the cobalt grade in the leaching slag, the leachate can also be returned to the zinc smelting system, achieving the purpose of efficient zinc recovery.

[0020] (4) The present invention can obtain high-grade cobalt-rich slag using low-grade cobalt slag as raw material, which can be used as raw material for cobalt smelting and extraction. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0022] The specific technical implementation scheme of the present invention is further described below through examples and drawings.

[0023] The process flow of the method for efficiently enriching cobalt and separating zinc and cobalt from purified cobalt slag provided by the embodiment of the present invention is as follows: Figure 1 shown.

[0024] In the embodiments of the present invention and the comparative examples, cobalt slag was purified from a hydrometallurgical zinc smelting enterprise in Henan Province. The purified cobalt slag mainly contained phases such as Zn(OH)2ZnSO4·4H2O and Zn, with the zinc and cobalt element contents being 56.36 wt.% and 0.43 wt.%, respectively.

[0025] Example 1

[0026] This embodiment provides a method for efficiently enriching cobalt in cobalt slag purified from a hydrometallurgical zinc smelting system, the specific steps of which are as follows:

[0027] Step 1: Dry the purified cobalt slag and calcine it at 400°C in air atmosphere for 60 minutes;

[0028] Step 2: After the roasted product is cooled, it is mixed with sulfuric acid solution. The pH of the leaching solution is 3.0, the pulp density is 10%, and the leaching is carried out at 70°C with mechanical stirring at 200 rpm for 30 minutes.

[0029] Step 3: The feed solution obtained in step 2 is filtered, and the obtained leachate is returned to the hydrometallurgical zinc smelting leachate purification system for electrolytic recovery of zinc in the leachate; the leachate residue obtained by filtration is washed with water and dried to obtain the cobalt-rich slag.

[0030] The test results showed that the cobalt content in the cobalt-rich slag obtained after leaching was 8.57 wt.%, the cobalt recovery rate was 86%, and the zinc leaching rate was 90%.

[0031] Comparative Example 1

[0032] This comparative example provides a method for efficiently enriching cobalt in cobalt slag purified from a hydrometallurgical zinc smelting system, and the specific steps are as follows:

[0033] Step 1: Leach the purified cobalt slag directly at a pH of 3.0, a slurry density of 10%, and 70°C for 30 minutes using mechanical stirring at 200 rpm;

[0034] Step 2: filtering the liquid obtained in step 1, and returning the obtained leachate to the hydrometallurgical zinc leaching liquid purification system for electrolytic recovery of zinc in the leachate; filtering the obtained leachate residue, washing it with water, and drying it;

[0035] The test results showed that the cobalt content in the leaching residue obtained after direct weak acid leaching was 1.02 wt.%, the cobalt recovery rate was 61%, and the zinc leaching rate was 82%.

[0036] The difference between Comparative Example 1 and Example 1 is that Example 1 first roasts the raw materials and then performs weak acid leaching of the valuable metal elements, while Comparative Example 1 directly performs weak acid leaching on the purified cobalt slag. The cobalt content in the leached slag and the zinc-cobalt separation effect are significantly different. Because the zinc and cobalt element phases in the purified cobalt slag are not regulated by roasting, some of the zinc in the raw materials remains in the form of metal salts that are difficult to leach, and cobalt compounds are also relatively easy to leach. As a result, the cobalt content in the leached slag is low, and the zinc-cobalt separation effect is not obvious. Therefore, in order to achieve efficient cobalt enrichment, it is very necessary to regulate the phase of the calcined purified cobalt slag.

[0037] Example 2

[0038] This embodiment provides a method for efficiently enriching cobalt in cobalt slag purified from a hydrometallurgical zinc smelting system, the specific steps of which are as follows:

[0039] Step 1: Dry the purified cobalt slag and calcine it at 500°C in air atmosphere for 90 minutes;

[0040] Step 2: After the roasted product is cooled, it is mixed with sulfuric acid solution. The pH of the solution during the leaching process is 4.0, the pulp density is 20%, and the leaching is carried out at 80°C with mechanical stirring at 300 rpm for 45 minutes;

[0041] Step 3: filtering the liquid obtained in step 2, and returning the obtained leachate to the hydrometallurgical zinc leaching liquid purification system for electrolytic recovery of zinc in the leachate; washing and drying the leaching residue obtained by filtration to obtain cobalt-rich residue;

[0042] The test results showed that the cobalt content in the cobalt-rich slag obtained after leaching was 10.81 wt.%, the cobalt recovery rate was 92%, and the zinc leaching rate was 93%.

[0043] Example 3

[0044] This embodiment provides a method for efficiently enriching cobalt in cobalt slag purified from a hydrometallurgical zinc smelting system, the specific steps of which are as follows:

[0045] Step 1: Dry the purified cobalt slag and calcine it at 500°C in air atmosphere for 120 minutes;

[0046] Step 2: After the roasted product is cooled, it is mixed with sulfuric acid solution. The pH of the leaching solution is 5.0, the pulp density is 30%, and the leaching is carried out at 90°C with mechanical stirring at 400 rpm for 60 minutes.

[0047] Step 3: filtering the liquid obtained in step 2, and returning the obtained leachate to the hydrometallurgical zinc leaching liquid purification system for electrolytic recovery of zinc in the leachate; washing and drying the leaching residue obtained by filtration to obtain cobalt-rich residue;

[0048] The test results showed that the cobalt content in the cobalt-rich slag obtained after leaching was 11.81 wt.%, the cobalt recovery rate was 95%, and the zinc leaching rate was 95%.

[0049] Example 4

[0050] This embodiment provides a method for efficiently enriching cobalt in cobalt slag purified from a hydrometallurgical zinc smelting system, the specific steps of which are as follows:

[0051] Step 1: Dry the purified cobalt slag and calcine it at 850°C in air atmosphere for 180 minutes;

[0052] Step 2: After the roasted product is cooled, it is mixed with sulfuric acid solution. The pH of the solution during the leaching process is 5.5, the pulp density is 40%, and the leaching is carried out at 90°C with mechanical stirring at 500 rpm for 60 minutes;

[0053] Step 3: filtering the liquid obtained in step 2, and returning the obtained leachate to the hydrometallurgical zinc leaching liquid purification system for electrolytic recovery of zinc in the leachate; washing and drying the leaching residue obtained by filtration to obtain cobalt-rich residue;

[0054] The test results showed that the cobalt content in the cobalt-rich slag obtained after leaching was 7.05 wt.%, the cobalt recovery rate was 80%, and the zinc leaching rate was 97%.

[0055] Example 5

[0056] This embodiment provides a method for efficiently enriching cobalt in cobalt slag purified from a hydrometallurgical zinc smelting system, the specific steps of which are as follows:

[0057] Step 1: Dry the purified cobalt slag and calcine it at 700°C in air atmosphere for 120 minutes;

[0058] Step 2: After the roasted product is cooled, it is mixed with sulfuric acid solution. The pH of the leaching solution is 5.0, the pulp density is 30%, and the leaching is carried out at 90°C with mechanical stirring at 400 rpm for 60 minutes.

[0059] Step 3: filtering the liquid obtained in step 2, and returning the obtained leachate to the hydrometallurgical zinc leaching liquid purification system for electrolytic recovery of zinc in the leachate; washing and drying the leaching residue obtained by filtration to obtain cobalt-rich residue;

[0060] The test results showed that the cobalt content in the cobalt-rich slag obtained after leaching was 5.47 wt.%, the cobalt recovery rate was 50%, and the zinc leaching rate was 97%.

[0061] Example 6

[0062] This embodiment provides a method for efficiently enriching cobalt in cobalt slag purified from a hydrometallurgical zinc smelting system, the specific steps of which are as follows:

[0063] Step 1: Dry the purified cobalt slag and calcine it at 500°C in air atmosphere for 120 minutes;

[0064] Step 2: After the roasted product is cooled, it is mixed with sulfuric acid solution. The pH of the solution during the leaching process is 4.0, the pulp density is 20%, and the leaching is carried out at 80°C with mechanical stirring at 300 rpm for 45 minutes;

[0065] Step 3: filtering the liquid obtained in step 2, and returning the obtained leachate to the hydrometallurgical zinc leaching liquid purification system for electrolytic recovery of zinc in the leachate; washing and drying the leaching residue obtained by filtration to obtain cobalt-rich residue;

[0066] The test results showed that the cobalt content in the cobalt-rich slag obtained after leaching was 6.63 wt.%, the cobalt recovery rate was 60%, and the zinc leaching rate was 96%.

[0067] Example 7

[0068] This embodiment provides a method for efficiently enriching cobalt in cobalt slag purified from a hydrometallurgical zinc smelting system, the specific steps of which are as follows:

[0069] Step 1: Dry the purified cobalt slag and calcine it at 500°C in air atmosphere for 120 minutes;

[0070] Step 2: After the roasted product is cooled, it is mixed with sulfuric acid solution. The pH of the solution during the leaching process is 5.5, the pulp density is 40%, and the leaching is carried out at 90°C with mechanical stirring at 500 rpm for 60 minutes;

[0071] Step 3: filtering the liquid obtained in step 2, and returning the obtained leachate to the hydrometallurgical zinc leaching liquid purification system for electrolytic recovery of zinc in the leachate; washing and drying the leaching residue obtained by filtration to obtain cobalt-rich residue;

[0072] The test results showed that the cobalt content in the cobalt-rich slag obtained after leaching was 7.12 wt.%, the cobalt recovery rate was 65%, and the zinc leaching rate was 85%.

[0073] It can be seen from the above examples that the cobalt percentage in the cobalt-rich slag obtained in Example 3 is the highest, and the zinc and cobalt recovery rates are the highest. By comparing the examples, it can be seen that the roasting temperatures of Examples 1 and 2 are relatively low, while the roasting temperature of Example 4 is relatively high, at 850°C; Examples 3 and 5 only differ in roasting temperature. By comparing the test results, it can be found that a roasting temperature that is too high will cause the cobalt percentage in the cobalt-rich slag to decrease. This result shows that a high roasting temperature is not conducive to the transformation of cobalt into insoluble cobalt-zinc composite oxides. This is because insoluble cobalt-zinc composite oxides will decompose again to form soluble CoO under high-temperature roasting conditions, thereby causing cobalt to dissolve in a weak acid solution, reducing the cobalt enrichment effect. By comparing Example 3, Example 6, and Example 7, it is known that under the same roasting temperature, if the pH value of the leaching solution is too low, the cobalt-zinc composite oxide will dissolve, and if the pH value is too high, the zinc oxide will not dissolve completely, both of which will cause a decrease in the cobalt content in the leaching slag.

[0074] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for efficiently enriching cobalt in cobalt slag purified from a hydrometallurgical zinc smelting system, characterized by: The main steps include: Step 1: drying the purified cobalt slag and then calcining it at a temperature of 400 to 850°C for 60 to 180 minutes to obtain a calcined product; Step 2: After the roasted product is cooled, it is mixed with a sulfuric acid solution, stirred and leached to obtain a feed solution; Step 3: Filter the feed liquid, and return the obtained leachate to the hydrometallurgical zinc leaching liquid purification system for deep purification; the leached residue obtained by filtration is washed with water and dried to obtain the cobalt-rich residue; The purified cobalt slag mainly comprises unreacted zinc powder, a composite compound of zinc hydroxide and sulfate, and a small amount of cobalt compound, wherein the mass percentage of cobalt element is 0.2-1.5 wt.%.

2. The method for efficiently enriching cobalt in cobalt slag purified from a hydrometallurgical zinc smelting system according to claim 1, characterized in that: The purified cobalt slag in step 1 is the cobalt-containing slag produced by treating the leachate with zinc powder replacement method during the hydrometallurgical zinc smelting process, including but not limited to arsenic salt, antimony salt, zinc-lead alloy powder zinc powder replacement method.

3. The method for efficiently enriching cobalt in cobalt slag purified from a hydrometallurgical zinc smelting system according to claim 1, characterized in that: The equipment used for the roasting in step 1 includes but is not limited to a roasting rotary kiln and a boiling furnace, which are equipment that can heat the purified cobalt slag.

4. The method for efficiently enriching cobalt in cobalt slag purified from a hydrometallurgical zinc smelting system according to claim 1, characterized in that: The pH of the sulfuric acid solution described in step 2 is 3.0 to 5.

5.

5. The method for efficiently enriching cobalt in cobalt slag purified from a hydrometallurgical zinc smelting system according to claim 1, characterized in that: The stirring leaching conditions described in step 2 are: leaching temperature of 70 ~ 90 ° C, slurry concentration of 10 ~ 40%, leaching time of 30 ~ 60 min, mechanical stirring during the leaching process, and stirring speed of 200 ~ 500 rpm.

6. The method for efficiently enriching cobalt in cobalt slag purified from a hydrometallurgical zinc smelting system according to claim 1, characterized in that: The hydrometallurgical zinc smelting leachate purification system described in step 3 is an existing industrial hydrometallurgical zinc smelting system, including zinc sulfide concentrate roasting, acid leaching, leachate purification, and electrolysis steps.

7. The method for efficiently enriching cobalt in cobalt slag purified from a hydrometallurgical zinc smelting system according to claim 1, characterized in that: The purified liquid after the deep purification described in step 3 is repeatedly returned to step 2 for leaching again.

8. The method for efficiently enriching cobalt in cobalt slag purified from a hydrometallurgical zinc smelting system according to claim 1, characterized in that: The calcination conditions in step 1 are a calcination temperature of 500° C. and a calcination time of 120 min.

Images