Method for recovering cobalt and nickel in iron slag

Abstract

The invention discloses a method for recycling cobalt and nickel in iron slag, and relates to the field of hydrometallurgy, the method comprises the following steps: taking the iron slag, carrying out primary acid pickling, and carrying out solid-liquid separation to obtain primary washing slag and primary washing water; carrying out secondary acid pickling on the primary washing residues, and carrying out solid-liquid separation to obtain secondary washing residues and secondary washing water; the secondary washing slag is subjected to alkali washing and solid-liquid separation, third washing water and third washing slag are obtained, the steps are repeated on subsequent batches of iron slag, the secondary washing water is used for first-time acid pickling of the next batch of iron slag, the third washing water is used for second-time acid pickling of the next batch of iron slag, and the third washing slag is waste slag. The subsequent batch of primary washing water is the cobalt and nickel recovery liquid. The recovery rate of cobalt elements and nickel elements in the iron slag is increased, meanwhile, water resources are saved, and the water using cost is reduced.

Description

Technical Field

[0001] The present application relates to the field of hydrometallurgy, and in particular to a method for recovering cobalt and nickel from iron slag. Background Art

[0002] There is a large amount of iron in nickel-cobalt raw materials such as cobalt hydroxide / nickel hydroxide / nickel cobalt hydroxide, which needs to be leached out and precipitated for removal.

[0003] At present, the iron slag obtained by precipitation after leaching of iron is scrapped. However, since a large amount of cobalt and nickel elements are entrained in the iron slag as alkali is added during the iron removal process, if the iron slag is directly scrapped, a large amount of cobalt and nickel elements will be lost. Summary of the invention

[0004] In view of the deficiencies of the above-mentioned related technologies, the present application provides a method for recovering cobalt and nickel in iron slag. The present application improves the recovery rate of cobalt and nickel in the iron slag by controlling the treatment time, system temperature and system pH, performing two acid washes and one alkaline wash on the iron slag, and at the same time, the recovery rate of cobalt and nickel in the iron slag is further improved by reusing the secondary wash water and the tertiary wash water, while also saving water resources and reducing water costs.

[0005] The present application provides a method for recovering cobalt and nickel from iron slag using the following technical solution: A method for recovering cobalt and nickel in iron slag comprises the following steps: taking the iron slag for the first pickling, and separating the solid and liquid to obtain a first washed slag and a first wash water; carrying out a second pickling on the first washed slag, and separating the solid and liquid to obtain a second washed slag and a second wash water; carrying out an alkali wash on the second washed slag, and obtaining a third wash water and a third washed slag after solid-liquid separation, and repeating the above steps for subsequent batches of iron slag, wherein the second wash water is used for the first pickling of the next batch of iron slag, and the third wash water is used for the second pickling of the next batch of iron slag, the third washed slag is waste slag, and the first wash water of the subsequent batches is the recovery liquid of cobalt and nickel.

[0006] Preferably, the pH of the first acid wash is 2.0-3.0, the pH of the second acid wash is 2.5-3.5, and the pH of the alkali wash is 7.0-9.0.

[0007] Preferably, the first pickling comprises the following steps: mixing iron slag, acid and secondary washing water, and washing for 50-70 minutes.

[0008] Preferably, the first pickling comprises the following steps: mixing iron slag, acid and secondary washing water, and washing for 60 minutes.

[0009] Preferably, the second pickling comprises the following steps: mixing the first wash residue, acid and the third wash water, and washing for 50-70 minutes.

[0010] Preferably, the second pickling comprises the following steps: mixing the first wash residue, acid and the third wash water, and washing for 60 minutes.

[0011] Preferably, the alkali washing comprises the following steps: mixing the secondary washing residue with alkali solution and washing for 50-70 minutes.

[0012] Preferably, the alkali washing comprises the following steps: mixing the secondary washing residue with alkali solution and washing for 60 minutes.

[0013] Preferably, the temperatures of the first acid wash, the second acid wash and the alkali wash are 55-60°C.

[0014] Preferably, the acid comprises one or more of sulfuric acid and hydrochloric acid.

[0015] Preferably, the acid is sulfuric acid.

[0016] Preferably, the acid comprises sulfuric acid at a concentration of 75%-85%.

[0017] Preferably, the acid comprises sulfuric acid at a concentration of 80%.

[0018] Preferably, the alkali in the alkali solution is a weak base.

[0019] Preferably, the alkali solution is made of water and lime.

[0020] Preferably, the cobalt content in the waste slag is not more than 0.4%, and the nickel content is not more than 0.04%.

[0021] Preferably, the cobalt content in the waste slag is not more than 0.4%, and the nickel content is not more than 0.03%.

[0022] Preferably, the recovered cobalt and nickel solutions are directly used for slurrying and preleaching of cobalt-nickel ore.

[0023] In summary, the present application includes at least one of the following beneficial technical effects: 1. The present application recovers cobalt and nickel in the iron slag by performing two acid washes and one alkaline wash on the iron slag, and improves the recovery rate of cobalt and nickel in the iron slag by controlling the pH value of the system.

[0024] 2. The present application further recovers the cobalt and nickel elements contained in the secondary and tertiary washing waters by simultaneously reusing the secondary and tertiary washing waters, thereby further improving the recovery rate of the cobalt and nickel elements; 3. This application saves water resources and reduces water costs by reusing the primary wash water, the secondary wash water and the tertiary wash water at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the process flow chart of this application. DETAILED DESCRIPTION

[0026] The present application is further described in detail below in conjunction with examples. The following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. In the following examples, if specific conditions are not specified, they are carried out according to normal conditions or conditions recommended by the manufacturer. The methods used are conventional methods known in the art unless otherwise specified, and the consumables and reagents used are commercially available unless otherwise specified. Unless otherwise specified, the professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the recorded content may also be applied to the present invention.

[0027] The raw materials used in the examples and comparative examples can all be obtained commercially.

[0028] Example 1 Example 1 of the present application provides a method for recovering cobalt and nickel from iron slag, referring to Figure 1 The specific steps are as follows: take the iron slag and add it to the primary slag washing slurry tank, slurry it, adjust the pH to 2.0-2.5 with 80% sulfuric acid, control the temperature to 55-60℃ and wash for 60min to complete the first acid washing, perform a first filter press through a filter press, separate the solid and liquid to obtain a primary slag and a primary wash water; add the primary slag washing slurry tank, slurry it, adjust the pH to 3.0-3.5 with 80% sulfuric acid, control the temperature to 55-60℃ and wash for 60min to complete the second acid washing, perform a second filter press through a filter press, separate the solid and liquid to obtain a secondary slag and a secondary wash water; The slag is added to a three-time slag washing slurry tank, and circulating steam condensate is added for slurrying. The pH is adjusted to 8.0-9.0 with lime, and the temperature is controlled at 55-60°C for 60 minutes to complete alkaline washing. The slag is filtered three times by a filter press, and three washing waters and three washing slags are obtained after solid-liquid separation. The above steps are repeated for subsequent batches of iron slag, wherein the second washing water is used for slurrying in the first pickling process of the next batch of iron slag, and the third washing water is used for slurrying in the second pickling process of the next batch of iron slag. The three washing slag is waste slag, and the first washing water of subsequent batches is the recovery liquid of cobalt and nickel, which is directly used for slurrying and pre-impregnation of cobalt-nickel ore.

[0029] Example 2 Example 2 of the present application provides a method for recovering cobalt and nickel from iron slag. The difference between Example 2 and Example 1 is that in Example 2, the pH value in the second pickling process is adjusted to 2.5-3.0, and the pH value in the alkaline washing process is adjusted to 7.0-8.0.

[0030] Comparative Example 1 Comparative Example 1 provides a method for recovering cobalt and nickel from iron slag. The difference between Comparative Example 1 and Example 1 is that: in Comparative Example 1, the pH value in the first pickling process is adjusted to 3.0-3.5; and the pH value in the second pickling process is adjusted to 3.0-3.5.

[0031] Comparative Example 2 Comparative Example 2 provides a method for recovering cobalt and nickel from iron slag. The difference between Comparative Example 2 and Example 1 is that: in Comparative Example 2, the pH in the first pickling process is adjusted to 3.0-3.5, and the washing time is 30 minutes; the washing time in the second pickling process is 30 minutes; and the washing time in the alkaline washing process is 30 minutes.

[0032] Comparative Example 3 Comparative Example 3 provides a method for recovering cobalt and nickel from iron slag. The difference between Comparative Example 3 and Example 2 is that: in Comparative Example 3, the pH value in the first pickling process is adjusted to 3.0-3.5; and the pH value in the second pickling process is adjusted to 3.0-3.5.

[0033] Comparative Example 4 Comparative Example 4 provides a method for recovering cobalt and nickel from iron slag. The difference between Comparative Example 4 and Example 2 is that: in Comparative Example 4, the temperature during the first pickling process is 50-55°C, and the washing time is 30 minutes; the temperature during the second pickling process is 50-55°C, and the washing time is 30 minutes; the temperature during the alkali washing process is 50-55°C, and the washing time is 30 minutes.

[0034] Test and Inspection The cobalt content and nickel content in the three-washed slag obtained by treating subsequent batches of iron slag using the method for recovering cobalt and nickel in iron slag of Examples 1-2 and Comparative Examples 1-4 were tested, and the test results are shown in Table 1 below. Table 1:

[0035] Results Analysis The following is a detailed description of the present application in conjunction with the experimental results provided in Table 1.

[0036] Referring to Table 1, the cobalt content in the three-wash slag obtained by treating the iron slag using the method for recovering cobalt and nickel in iron slag of Examples 1-2 is less than 0.4%, and the nickel content is less than 0.03%. Among them, the cobalt content in the three-wash slag obtained by treating the iron slag using the method for recovering cobalt and nickel in iron slag of Example 1 is only 0.2%, and the nickel content is only 0.017%, indicating that controlling the pH value in the second acid washing process to 3.0-3.5 and the pH value in the alkali washing process to 8.0-9.0 is beneficial to improving the recovery rate of cobalt and nickel elements in the iron slag.

[0037] Taking Example 1 as a reference, Comparative Example 1 shows the influence of system pH on the recovery rate of cobalt and nickel in iron slag during the first pickling and the second pickling, wherein the cobalt content and nickel content in the three-washed slag obtained by treating the iron slag with the method for recovering cobalt and nickel in iron slag of Example 1 are much lower than the cobalt content and nickel content in the three-washed slag obtained by treating the iron slag with the method for recovering cobalt and nickel in iron slag of Comparative Example 1, and the cobalt content and nickel content in the three-washed slag obtained by treating the iron slag with the method for recovering cobalt and nickel in iron slag of Example 1 are only one third of the cobalt content and nickel content in the three-washed slag obtained by treating the iron slag with the method for recovering cobalt and nickel in iron slag of Comparative Example 1; With Example 2 as a reference, Comparative Example 3 shows the effect of system pH on the recovery rate of cobalt and nickel in iron slag during the first pickling and the second pickling, wherein the cobalt content and nickel content in the three-wash slag obtained by treating the iron slag with the method for recovering cobalt and nickel in iron slag of Example 2 are much lower than the cobalt content and nickel content in the three-wash slag obtained by treating the iron slag with the method for recovering cobalt and nickel in iron slag of Comparative Example 3, and the cobalt content and nickel content in the three-wash slag obtained by treating the iron slag with the method for recovering cobalt and nickel in iron slag of Example 2 are only half of the cobalt content and nickel content in the three-wash slag obtained by treating the iron slag with the method for recovering cobalt and nickel in iron slag of Comparative Example 3. In summary, it is shown that controlling the system pH to 2.0-3.0 during the first pickling and the second pickling is beneficial to improving the recovery rate of cobalt and nickel in iron slag.

[0038] With Example 1 and Comparative Example 1 as reference, Comparative Example 2 demonstrates the influence of the washing time of the first pickling, the second pickling and the alkali washing on the recovery rate of cobalt and nickel in the iron slag, wherein the cobalt content and the nickel content in the three-washed slag obtained by treating the iron slag with the method for recovering cobalt and nickel in the iron slag of Example 1 are much lower than the cobalt content and the nickel content in the three-washed slag obtained by treating the iron slag with the method for recovering cobalt and nickel in the iron slag of Comparative Example 2, and the cobalt content and the nickel content in the three-washed slag obtained by treating the iron slag with the method for recovering cobalt and nickel in the iron slag of Comparative Example 2 are slightly higher than the cobalt content and the nickel content in the three-washed slag obtained by treating the iron slag with the method for recovering cobalt and nickel in the iron slag of Comparative Example 1, indicating that controlling the washing time of the first pickling, the second pickling and the alkali washing to 60 minutes is beneficial to improving the recovery rate of cobalt and nickel in the iron slag.

[0039] With Example 2 as a reference, Comparative Example 4 shows the influence of system temperature and washing time on the recovery rate of cobalt and nickel in iron slag during the first pickling, second pickling and alkali washing processes, wherein the cobalt content and nickel content in the three-washed slag obtained by treating the iron slag with the method for recovering cobalt and nickel in iron slag in Example 2 are much lower than the cobalt content and nickel content in the three-washed slag obtained by treating the iron slag with the method for recovering cobalt and nickel in iron slag in Comparative Example 4, and the cobalt content and nickel content in the three-washed slag obtained by treating the iron slag with the method for recovering cobalt and nickel in iron slag in Example 1 are more than 30% less than the cobalt content in the three-washed slag obtained by treating the iron slag with the method for recovering cobalt and nickel in iron slag in Example 1, and the nickel content is nearly half less, indicating that controlling the system temperature to 55-60°C and the washing time to 60min during the first pickling, second pickling and alkali washing processes is beneficial to improving the recovery rate of cobalt and nickel in iron slag.

[0040] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for recovering cobalt and nickel from iron slag, characterized in that: The following steps are involved: The iron slag is subjected to the first pickling, and solid-liquid separation is performed to obtain primary washed slag and primary washing water; the primary washed slag is subjected to the second pickling, and solid-liquid separation is performed to obtain secondary washed slag and secondary washing water; the secondary washed slag is subjected to alkali washing, and solid-liquid separation is performed to obtain tertiary washing water and tertiary washed slag, and the above steps are repeated for subsequent batches of iron slag, wherein the secondary washing water is used for the first pickling of the next batch of iron slag, and the tertiary washing water is used for the second pickling of the next batch of iron slag, the tertiary washed slag is waste slag, and the primary washing water of subsequent batches is the recovery liquid of cobalt and nickel.

2. A method for recovering cobalt and nickel from iron slag according to claim 1, characterized in that: The pH of the first acid wash is 2.0-3.0, the pH of the second acid wash is 2.5-3.5, and the pH of the alkali wash is 7.0-9.

0.

3. The method for recovering cobalt and nickel from iron slag according to claim 1, characterized in that: The first pickling comprises the following steps: mixing iron slag, acid and secondary washing water, and washing for 50-70 minutes.

4. The method for recovering cobalt and nickel from iron slag according to claim 1, characterized in that: The second pickling comprises the following steps: mixing the first washing residue, acid and the third washing water, and washing for 50-70 minutes.

5. The method for recovering cobalt and nickel from iron slag according to claim 1, characterized in that: The alkali washing comprises the following steps: Mix the secondary washing residue with alkali solution and wash for 50-70 minutes.

6. The method for recovering cobalt and nickel from iron slag according to claim 1, characterized in that: The temperatures of the first acid wash, the second acid wash and the alkali wash are 55-60°C.

7. The method for recovering cobalt and nickel from iron slag according to claim 3, characterized in that: The acid includes one or more of sulfuric acid and hydrochloric acid.

8. The method for recovering cobalt and nickel from iron slag according to claim 7, characterized in that: The acid includes sulfuric acid having a concentration of 75% to 85%.

9. The method for recovering cobalt and nickel from iron slag according to claim 5, characterized in that: The lye is made from water and lime.

10. The method for recovering cobalt and nickel from iron slag according to claim 1, characterized in that: The cobalt content in the waste slag is not more than 0.4%, and the nickel content is not more than 0.04%.

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