Nickel recycling and harmless treatment method for nickel electrolysis waste diaphragm bag

Abstract

The invention provides a nickel recycling and harmless treatment method for a nickel electrolysis waste diaphragm bag. The method comprises the process links of checking and cleaning, soaking and softening, oxidation and iron removal, nickel-rich acid adjustment, pressurized acid leaching, harmless treatment and iron slag leaching. According to the method, a normal-pressure and pressure leaching process is adopted, nickel and iron carried in the waste diaphragm bag are effectively leached and separated, a nickel sulfate solution meeting a nickel electrolysis production system is obtained through circulating enrichment for supplementing nickel for the waste diaphragm bag, produced iron slag meets the iron-containing index requirement of a steelmaking enterprise and serves as an iron raw material to be sold and treated, and the nickel in the waste diaphragm bag is subjected to harmless treatment; and the win-win effect of nickel recovery and harmless treatment is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of nonferrous hydrometallurgy and relates to a method for recovering nickel from waste diaphragm bags of nickel electrolysis and for harmlessly treating the bags. Background Art

[0002] A large number of waste diaphragm bags are generated in the production of existing soluble anode diaphragm electrolytic nickel. The early treatment method of the waste diaphragm bags is to directly export them for secondary use by the public, but there are problems of loss of valuable metals such as nickel and cobalt and heavy metal pollution. The current treatment method is to send them to pyrometallurgical furnaces for combustion to recover nickel. The combustion of textiles has increased the pressure on the treatment of flue gas from pyrometallurgical furnaces. At the same time, there is still a problem of low nickel yield. Therefore, in order to solve the above problems, the present invention provides a method that can achieve efficient recovery and harmless treatment of nickel from nickel electrolytic waste diaphragm bags. Summary of the invention

[0003] The purpose of the present invention is to provide a method for recovering nickel and harmlessly treating waste diaphragm bags from nickel electrolysis in response to the problems existing in the prior art, thereby solving the problem that the existing waste diaphragm bag treatment process not only increases the pressure on fume control of pyrometallurgical furnaces, but also has a low nickel yield.

[0004] To this end, the present invention adopts the following technical solutions: A method for recovering nickel from waste diaphragm bags of nickel electrolysis and harmlessly treating the waste diaphragm bags comprises the following steps: Step a. Inspection and cleaning: Check the inside and outside of the used diaphragm bags one by one, remove the electrolytic nickel particles attached to the diaphragm bags to prevent them from entering the pressurized acid leaching to produce hydrogen, and clean out the nickel hydroxide and other debris deposited in the used diaphragm bags.

[0005] Step b. Soaking and softening: Put the leached liquid produced by eluting iron slag and the rinsed liquid produced by the first rinse into the reaction tank, add an appropriate amount of new water, mix them evenly, arrange them into the inspected waste diaphragm bags, heat them to a certain temperature and soak them, so that the filter holes of the waste diaphragm bags absorb water and expand and become soft; Specifically, in step b, the soaking temperature is 30-50° C., and the soaking time is ≮24 h.

[0006] Step c. Oxidation for iron removal: Continue to heat the solution in the reaction tank, start the circulation pump, slowly and evenly add a strong oxidant dilution solution to remove the hydrolyzed iron precipitate attached to the surface of the waste diaphragm bag, remove the brown color on the surface, and allow the hydrolyzed iron to dissolve back into the solution in an ionic state. After the brown color on the surface completely disappears, remove the waste diaphragm bag; Specifically, in step c, the strong oxidant is any one of hydrogen peroxide or potassium peroxide, the reaction temperature is 70-90°C, the reaction time is 4-6h, and the oxidized iron removal liquid can be reused multiple times. 2+When the concentration is ≥40g / l, it is sent to the nickel-enriched acid adjustment step.

[0007] Step d. nickel-enriched acid adjustment: adding the nickel hydroxide cleaned out from the inspection to the liquid after oxidative iron removal, and adding part of the nickel sulfate solution produced by pressurized acid leaching to enrich the nickel ion concentration, and then adding an appropriate amount of sulfuric acid to adjust the acidity, which is used as the pre-pressurized acid leaching liquid; Specifically, the nickel-enriched acid-adjusted solution in step d contains 15 to 30 g / l of acid.

[0008] Step e. Pressurized acid leaching: the waste diaphragm bags after oxidation and iron removal are moved into a pressure autoclave and arranged and placed, and a nickel-rich acid-adjusted solution is introduced, the solution is circulated internally, and the temperature and pressure are increased. Under certain pressure conditions, valuable metals such as nickel attached to the waste diaphragm bags are dissolved back into the solution, and the ionic iron in the solution is precipitated in the form of hematite. The pressurized leaching solution is filtered to obtain a nickel sulfate solution and a pressurized iron removal slag. Part of the nickel sulfate solution is enriched with nickel to adjust the acid and enrich the nickel ion concentration, and the remaining part of the nickel sulfate solution is supplied to the nickel electrolysis system to supplement nickel; Specifically, in step e, the pressure acid leaching reaction temperature is 190-220°C, the leaching pressure is 1.8-2.4 MPa, the reaction time is 4-6 hours, and the nickel sulfate solution Ni 2+ ≥65g / l, the direct recovery rate of nickel is ≥98.5%, when the nickel sulfate solution Ni produced by pressure acid leaching is 2+ When the concentration is ≯65g / l, return to step d to circulate and enrich nickel.

[0009] Step f. harmless treatment: control the waste diaphragm bag solution after pressurized acid leaching, perform a rinse, neutralize the waste diaphragm bag with a dilute alkali solution after the rinse, rinse the waste diaphragm bag with new water for a second time after the neutralization treatment to make it completely harmless, use the second rinse solution for the first rinse, and return the rinse solution produced by the first rinse to soak and soften for the preparation of the front solution, and the diaphragm bag is exported after the harmless treatment; Specifically, the dilute alkali solution in step f is a sodium hydroxide solution with a mass percentage concentration of 15 to 20%.

[0010] Step g. Iron slag washing: The iron-removing slag produced by pressurized acid leaching is continuously leached in countercurrent to make the iron slag after leaching contain Ni≯0.5% and Fe≥53%, and is exported as iron raw material. The leached liquid is returned for soaking and softening for the preparation of the front liquid.

[0011] The beneficial effects of the present invention are: The present invention adopts normal pressure and pressurized leaching processes to effectively leach and separate nickel and iron entrained in waste diaphragm bags, obtains nickel sulfate solution that meets the nickel electrolysis production system through cyclic enrichment to supplement nickel, and produces iron slag that meets the iron content index requirements of steelmaking enterprises and is sold as iron raw material. The nickel in the waste diaphragm bags is harmlessly treated, achieving a win-win effect of nickel recovery and harmless treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0013] The technical solution of the present invention is described below in conjunction with the accompanying drawings and implementation methods.

[0014] Example 1 The discarded diaphragm bags of a nickel electrolysis production system are light green inside, with a small amount of light green residue at the bottom. The outside of the bag is brown. There are irregular nickel blocks of varying sizes at the bottom of some diaphragm bags. The weight percentages of the main components are: Ni 2.45-2.51%, Cu 0.08-0.09%, Fe 0.55-0.61%, Co ≤0.01%, ash 96.75-96.78%, and others ≤0.001%.

[0015] like Figure 1 As shown, the method for recovering nickel and harmlessly treating waste diaphragm bags for nickel electrolysis comprises the following steps: Step a. Inspection and cleaning: Check the inside and outside of the waste diaphragm bags one by one, remove the irregular nickel blocks attached to the diaphragm bags to prevent them from entering the pressurized acid leaching to produce hydrogen, and clean out the nickel hydroxide and other debris deposited in the waste diaphragm bags; Step b. Soaking and softening: Put the leached liquid produced by iron slag leaching and the rinsed liquid produced by the first rinse into the reaction tank, add an appropriate amount of new water, mix evenly, arrange and put the inspected waste diaphragm bags, control the temperature between 37 and 44°C after heating, and soak for 24 hours to make the filter pores of the waste diaphragm bags absorb water, expand and soften; Step c. Oxidation for iron removal: Continue to heat the solution in the reaction tank, start the circulation pump, slowly and evenly add 15% mass percent hydrogen peroxide mother solution, the reaction temperature is 81-87℃, the reaction time is 5h, wait until the brown color on the surface completely fades, remove the waste diaphragm bag, reuse the solution after oxidation for iron removal 11 times, wait until the solution contains Ni 2+ 43.45 g / l, sent to step d for further reaction; Step d. Nickel-enriched acid adjustment: Add the nickel hydroxide cleaned out from the oxidation deironing solution under stirring, and add part of the nickel sulfate solution produced by pressurized acid leaching to enrich the nickel ion concentration, add an appropriate amount of sulfuric acid, and the nickel-enriched acid adjustment solution contains Ni 2+57.78g / l, containing 25.12g / l acid, used as pre-pressurized acid leaching solution; Step e. Pressurized acid leaching: After the iron removal by oxidation, the waste diaphragm bags are moved into the autoclave and arranged and placed, and the nickel-rich acid-adjusted solution is introduced. The solution is circulated internally, heated to 209°C, the leaching pressure is 2.0MPa, and the reaction is carried out for 6h to obtain Ni-containing 2+ 65.91g / l nickel sulfate solution; a portion of the nickel sulfate solution is returned to enrich nickel to adjust the acidity and enrich nickel ion concentration, and the remaining portion is sent to the nickel electrolysis system to supplement nickel, and the direct recovery rate of nickel is 98.9%; Step f. Harmless treatment: drain the waste diaphragm bag solution after pressurized acid leaching, perform a rinse, neutralize the waste diaphragm bag with a dilute alkali solution after the rinse, rinse the waste diaphragm bag with new water for a second time after the neutralization to make it completely harmless, use the solution after the second rinse for the first rinse, and use the solution after the first rinse to soften and prepare the pre-liquid, and sell the diaphragm bag after the harmless treatment; Step g. Iron slag elution: The iron-removing slag produced by pressure acid leaching is continuously eluted at more than three levels of countercurrent. After elution, the iron slag contains 0.48% Ni and 54.11% Fe, which is exported as iron raw material. The eluted liquid is returned for soaking and softening for the preparation of the front liquid.

[0016] Example 2 The discarded diaphragm bags of a nickel electrolysis production system are light green inside, with a small amount of light green residue at the bottom. The outside of the bag is brown. There are irregular nickel blocks of varying sizes at the bottom of some diaphragm bags. The weight percentages of the main components are: Ni 2.45-2.51%, Cu 0.08-0.09%, Fe 0.55-0.61%, Co ≤0.01%, ash 96.75-96.78%, and others ≤0.001%.

[0017] The method for recovering nickel from waste diaphragm bags of nickel electrolysis and harmlessly treating the waste diaphragm bags comprises the following steps: Step a. Inspection and cleaning: Check the inside and outside of the waste diaphragm bags one by one, remove the irregular nickel blocks attached to the diaphragm bags to prevent them from entering the pressurized acid leaching to produce hydrogen, and clean out the nickel hydroxide and other debris deposited in the waste diaphragm bags; Step b. Soaking and softening: Put the leached liquid produced by iron slag leaching and the rinsed liquid produced by the first rinse into the reaction tank, add an appropriate amount of new water, mix evenly, arrange and put the inspected waste diaphragm bags, control the temperature between 36 and 45°C after heating, and soak for 24 hours to make the filter pores of the waste diaphragm bags absorb water, expand and soften; Step c. Oxidation for iron removal: Continue to heat the solution in the reaction tank, start the circulation pump, slowly and evenly add 15% mass percent hydrogen peroxide mother solution, the reaction temperature is 83-89℃, the reaction time is 4h, wait until the brown color on the surface completely fades, remove the waste diaphragm bag, reuse the solution after oxidation for iron removal 9 times, wait until the solution contains Ni 2+ 41.99 g / l, sent to step d; Step d. Nickel-enriched acid adjustment: Add the nickel hydroxide cleaned out from the oxidation deironing solution under stirring, and add part of the nickel sulfate solution produced by pressurized acid leaching to enrich the nickel ion concentration, add an appropriate amount of sulfuric acid, and the nickel-enriched acid adjustment solution contains Ni 2+ 58.01g / l, containing 23.67g / l of acid, used as pre-liquid for pressurized pickling; Step e. Pressurized acid leaching: After the iron removal by oxidation, the waste diaphragm bags are moved into the autoclave and arranged and placed, and the nickel-rich acid-adjusted solution is introduced. The solution is circulated internally, heated to 197°C, the leaching pressure is 2.0 MPa, and the reaction is carried out for 6 hours to obtain Ni-containing 2+ 66.43g / l nickel sulfate solution; a portion of the nickel sulfate solution is returned to enrich nickel to adjust the acidity and enrich nickel ion concentration, and the remaining portion is sent to the nickel electrolysis system to supplement nickel; the direct recovery rate of nickel is 98.6%; Step f. Harmless treatment: drain the waste diaphragm bag solution after pressurized acid leaching, perform a rinse, neutralize the waste diaphragm bag with a dilute alkali solution after the rinse, rinse the waste diaphragm bag with new water for a second time after the neutralization to make it completely harmless, use the solution after the second rinse for the first rinse, and use the solution after the first rinse to soften and prepare the pre-liquid, and sell the diaphragm bag after the harmless treatment; Step g. Iron slag elution: The iron-removing slag produced by pressure acid leaching is continuously eluted at more than three levels of countercurrent. After elution, the iron slag contains 0.49% Ni and 54.26% Fe, which is exported as iron raw material. The eluted liquid is returned for soaking and softening for the preparation of the front liquid.

[0018] Example 3 The discarded diaphragm bags of a nickel electrolysis production system are light green inside, with a small amount of light green residue at the bottom. The outside of the bag is brown. There are irregular nickel blocks of varying sizes at the bottom of some diaphragm bags. The weight percentages of the main components are: Ni 2.45-2.51%, Cu 0.08-0.09%, Fe 0.55-0.61%, Co ≤0.01%, ash 96.75-96.78%, and others ≤0.001%.

[0019] The method for recovering nickel from waste diaphragm bags of nickel electrolysis and harmlessly treating the waste diaphragm bags comprises the following steps: Step a. Inspection and cleaning: Check the inside and outside of the waste diaphragm bags one by one, remove the irregular nickel blocks attached to the diaphragm bags to prevent them from entering the pressurized acid leaching to produce hydrogen, and clean out the nickel hydroxide and other debris deposited in the waste diaphragm bags; Step b. Soaking and softening: Put the leached liquid produced by iron slag leaching and the rinsed liquid produced by the first rinse into the reaction tank, add an appropriate amount of new water, mix evenly, arrange and put the inspected waste diaphragm bags, control the temperature between 41 and 50°C after heating, and soak for 24 hours to make the filter pores of the waste diaphragm bags absorb water, expand and soften; Step c. Oxidation for iron removal: Continue to heat the solution in the reaction tank, start the circulation pump, slowly and evenly add 15% mass percent hydrogen peroxide mother solution, the reaction temperature is 85-90℃, the reaction time is 4h, wait until the brown color on the surface completely fades, remove the waste diaphragm bag, reuse the solution after oxidation for 11 times, wait until the solution contains Ni 2+ 44.01 g / l, sent to step d; Step d. Nickel-enriched acid adjustment: Add the nickel hydroxide cleaned out from the oxidation deironing solution under stirring, and add part of the nickel sulfate solution produced by pressurized acid leaching to enrich the nickel ion concentration, add an appropriate amount of sulfuric acid, and the nickel-enriched acid adjustment solution contains Ni 2+ 55.29g / l, containing 27.13g / l acid, used as pre-pressurized acid leaching solution; Step e. Pressurized acid leaching: After the iron removal by oxidation, the waste diaphragm bags are moved into the autoclave and arranged and placed, and the nickel-rich acid-adjusted solution is introduced. The solution is circulated internally, heated to 193°C, the leaching pressure is 2.0 MPa, and the reaction is carried out for 6 hours to obtain Ni-containing 2+ 66.03g / l nickel sulfate solution, of which a portion of the nickel sulfate solution is returned to nickel enrichment to adjust the nickel ion concentration, and the remaining portion is sent to the nickel electrolysis system to supplement nickel; the direct recovery rate of nickel is 98.7%; Step f. Harmless treatment: drain the waste diaphragm bag solution after pressurized acid leaching, perform a rinse, neutralize the waste diaphragm bag with a dilute alkali solution after the rinse, rinse the waste diaphragm bag with new water for a second time after the neutralization to make it completely harmless, use the solution after the second rinse for the first rinse, and use the solution after the first rinse to soften and prepare the pre-liquid, and sell the diaphragm bag after the harmless treatment; Step g. Iron slag elution: The iron-removing slag produced by pressure acid leaching is continuously eluted at more than three levels of countercurrent. After elution, the iron slag contains 0.5% Ni and 55.0% Fe, which is exported as iron raw material. The eluted liquid is returned for soaking and softening for the preparation of the front liquid.

Claims

1. A method for recovering nickel from waste diaphragm bags for nickel electrolysis and for harmless treatment, characterized in that: It includes inspection and cleaning - soaking and softening - oxidation and iron removal - nickel-enriched acid adjustment - pressure acid leaching - harmless treatment - iron slag leaching process. The specific process steps are as follows: Step a. Inspection and cleaning: Check the inside and outside of the waste diaphragm bags one by one, remove the electrolytic nickel particles attached to the diaphragm bags to prevent the entry of pressurized acid leaching to produce hydrogen, and clean out the nickel hydroxide and other debris deposited in the waste diaphragm bags; Step b. Soaking and softening: Put the leached liquid produced by eluting iron slag and the rinsed liquid produced by the first rinse into the reaction tank, add an appropriate amount of new water, mix evenly, arrange and put the inspected waste diaphragm bags, heat to a certain temperature and soak them, so that the filter pores of the waste diaphragm bags absorb water and expand and become soft; Step c. Oxidation for iron removal: Continue to heat the solution in the reaction tank, start the circulation pump, slowly and evenly add the strong oxidant dilution solution, remove the hydrolyzed iron precipitate attached to the surface of the waste diaphragm bag, remove the brown color on the surface, and make the hydrolyzed iron dissolve back into the solution in an ionic state. After the brown color on the surface completely disappears, remove the waste diaphragm bag; Step d. nickel-enriched acid adjustment: adding the nickel hydroxide cleaned out from the inspection to the liquid after oxidative iron removal, and adding part of the nickel sulfate solution produced by pressurized acid leaching to enrich the nickel ion concentration, and then adding an appropriate amount of sulfuric acid to adjust the acidity, which is used as the pre-pressurized acid leaching liquid; Step e. Pressurized acid leaching: the waste diaphragm bags after oxidation and iron removal are moved into a pressure autoclave and arranged and placed, and a nickel-rich acid-adjusted solution is introduced, the solution is circulated internally, and the temperature and pressure are increased. Under certain pressure conditions, valuable metals such as nickel attached to the waste diaphragm bags are dissolved back into the solution, and the ionic iron in the solution is precipitated in the form of hematite. The pressurized leaching solution is filtered to obtain a nickel sulfate solution and a pressurized iron removal slag. Part of the nickel sulfate solution is enriched with nickel to adjust the acid and enrich the nickel ion concentration, and the remaining part of the nickel sulfate solution is supplied to the nickel electrolysis system to supplement nickel; Step f. harmless treatment: control the waste diaphragm bag solution after pressurized acid leaching, perform a rinse, neutralize the waste diaphragm bag with a dilute alkali solution after the rinse, rinse the waste diaphragm bag with new water for a second time after the neutralization treatment to make it completely harmless, use the second rinse solution for the first rinse, and return the rinse solution produced by the first rinse to soak and soften for the preparation of the front solution, and the diaphragm bag is exported after the harmless treatment; Step g. Iron slag washing: The iron-removing slag produced by pressurized acid leaching is continuously leached in countercurrent to make the iron slag after leaching contain Ni≯0.5% and Fe≥53%, and is exported as iron raw material. The leached liquid is returned for soaking and softening for the preparation of the front liquid.

2. The method for recovering nickel from waste diaphragm bags for nickel electrolysis and harmless treatment according to claim 1, characterized in that: In step b, the soaking temperature is 30-50° C. and the soaking time is ≮24 hours.

3. The method for recovering nickel from waste diaphragm bags for nickel electrolysis and harmless treatment according to claim 1, characterized in that: In the step c, the strong oxidant is any one of hydrogen peroxide and potassium peroxide, the reaction temperature is 70-90°C, the reaction time is 4-6h, and the oxidized iron removal liquid can be reused multiple times. 2+ When the concentration is ≥40g / l, it is sent to the nickel-enriched acid adjustment step.

4. The method for recovering nickel from waste diaphragm bags for nickel electrolysis and harmless treatment according to claim 1, characterized in that: In the step d, the nickel-enriched acid-adjusted solution contains 15 to 30 g / l of acid.

5. The method for recovering nickel from waste diaphragm bags for nickel electrolysis and harmless treatment according to claim 1, characterized in that: In step e, the pressure acid leaching reaction temperature is 190-220° C., the leaching pressure is 1.8-2.4 MPa, the reaction time is 4-6 hours, and the nickel sulfate solution Ni 2+ ≥65g / l, the direct recovery rate of nickel is ≥98.5%, when the nickel sulfate solution Ni produced by pressure acid leaching is 2+ When the concentration is ≯65g / l, return to step d to circulate and enrich nickel.

6. The method for recovering nickel from waste diaphragm bags for nickel electrolysis and harmless treatment according to claim 1, characterized in that: The dilute alkali solution in step f is a sodium hydroxide solution with a mass percentage concentration of 15-20%.

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