Method for recovering cobalt from purified cobalt slag
By passing the purified cobalt slag through pickling and carbothermal chlorination, combined with oxidant treatment, the efficient enrichment of cobalt was successfully achieved, and the oxidation of prepared in the existing technology was solved. The solid content of cobalt is higher than 70%, achieving efficient recycling and resource utilization of cobalt resources.
Patent Information
- Application Number
- CN202311111153.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-08-31
- Publication Date
- 2024-12-27
- Estimated Expiration
- 2043-08-31
AI Technical Summary
In the prior art, when cobalt is recovered from purified cobalt slag, the oxidation precipitation method has poor impurity removal effect, and the selective acid leaching method cannot effectively separate zinc cobalt. The ammonia-ammonium salt leaching method has a long process chain and a high risk of environmental pollution. The solvent extraction method Cost is high and the process is complex.
By drying and grinding the purified cobalt slag into powder, mixing aqueous hydrochloric acid solution and then performing pickling, mixing with tar and calcining, the leaching liquid and dust collection powder are collected by cycling of leaching tower, and the cobalt oxide powder is obtained by oxidizing agent treatment, and cobalt oxide powder is obtained by oxidizing agent treatment. , achieve efficient enrichment of cobalt.
This method achieves efficient cobalt enrichment, with a solid content of cobalt oxide up to 70%, simplifying the process flow, reducing the cost of hazardous waste treatment in resource utilization, and the process is safe and reliable.
Smart Images
Figure CN117127023B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of industrial solid waste resource utilization, and in particular relates to a method for recovering cobalt from purified cobalt slag. Background Art
[0002] In order to achieve the unique properties of materials, cobalt is indispensable in the synthesis of catalytic materials, the preparation of special alloys, and the improvement of battery material performance. The consumption of cobalt in chemical, aerospace, biological, medical and other industries is increasing. Therefore, it is of great practical significance to recover cobalt resources from cobalt-containing solid waste. At present, the methods for recovering cobalt from purified cobalt slag include: ammonia-ammonium salt leaching method, solvent extraction method, oxidation precipitation method and selective acid leaching method.
[0003] The oxidation precipitation method has a short process flow, but if the oxidant is directly added to the cobalt slag or cobalt leaching solution, the impurity removal effect is poor, and the oxidant and precipitant loss is high. The selective acid leaching method has a simple process, but it cannot effectively separate zinc and cobalt, and will subsequently consume additional oxidants and alkaline precipitants, and will also introduce additional impurities by reacting with the oxidant and alkaline precipitant. Although the ammonia-ammonium salt leaching method increases the selectivity of cobalt leaching, the process chain is too long, and the operating environment is poor. The ammonia-ammonium salt loss is serious and there is a risk of secondary environmental pollution. The solvent extraction method can efficiently dispose of cobalt-containing solutions with many types of impurities and high impurity content, and has a good impurity removal effect, but the cost of organic solvents is high, and the extraction effect is greatly affected by the pH of the solution, and the process is also relatively complicated.
[0004] Therefore, based on the shortcomings of the existing process of purifying cobalt slag to extract cobalt, the development of a new and efficient process for purifying cobalt slag to extract cobalt has important practical significance for solving the current problems in the field of cobalt slag extraction. Summary of the invention
[0005] The present invention aims to solve at least one of the technical problems existing in the prior art and provides a method for recovering cobalt from purified cobalt slag.
[0006] The present invention provides a method for recovering cobalt from purified cobalt slag, the method comprising:
[0007] The purified cobalt slag is dried and ground for the first time to obtain cobalt slag powder;
[0008] The hydrochloric acid aqueous solution and the cobalt slag powder are mixed, stirred, and solid-liquid separated to obtain a solid part as pickling mud;
[0009] The pickling mud is dried, and the tar is mixed with the dried pickling mud, stirred, and ground for a second time to obtain the carbon-loaded pickling mud;
[0010] The carbon-loaded pickling mud is transferred to a chlorination furnace for calcination, and the flue gas generated during the calcination process is circulated and absorbed by a leaching tower after dust collection, and the leaching liquid and dust collection powder are recovered;
[0011] The mixed and recovered washing liquid and the dust collecting powder are stirred and solid-liquid separated to obtain a liquid portion which is a zinc-cobalt chloride enriched liquid;
[0012] Adding an oxidant to the zinc-cobalt chloride enriched solution, stirring and heating, to obtain a zinc-cobalt oxide enriched solution;
[0013] Sodium hydroxide solution is dripped into the zinc oxide cobalt enriched solution until the pH value is 4-7, aged, and solid-liquid separated to obtain a solid part of trivalent cobalt hydroxide, which is dried, calcined, and ground for the third time to obtain cobalt oxide powder.
[0014] Optionally, the liquid-to-solid ratio of the hydrochloric acid aqueous solution to the cobalt slag powder is 1.5-7.5:1 mL / g.
[0015] Optionally, the concentration of the hydrochloric acid aqueous solution is 0.5-7.5M.
[0016] Optionally, the mass ratio of the tar to the dried pickling mud is 2.5-7.5:100.
[0017] Optionally, the calcination temperature of the chlorination furnace is 650-850° C.; and / or,
[0018] The chlorine content introduced into the chlorination furnace is 85% to 95%; and / or,
[0019] The eluent is a 0.5-7.5M hydrochloric acid aqueous solution.
[0020] Optionally, the solid-liquid ratio of the oxidant to the zinc-cobalt chloride enriched solution is 2.5-12.5:100 g / mL.
[0021] Optionally, the first grinding time ranges from 0.5 to 4.5 hours; and / or,
[0022] The time range of the second grinding is 0.5 to 1.5 hours.
[0023] Optionally, the stirring time ranges from 0.5 to 2.5 hours.
[0024] Optionally, the heating temperature ranges from 75 to 125°C.
[0025] Optionally, the aging time ranges from 0.5 to 1.5 hours.
[0026] The invention provides a method for recovering cobalt from purified cobalt slag. The method comprises: drying the purified cobalt slag, grinding to obtain cobalt slag powder; mixing a hydrochloric acid aqueous solution and the cobalt slag powder, stirring, and performing solid-liquid separation to obtain a solid part as pickling mud; drying the pickling mud, mixing tar with the dried pickling mud, stirring, and grinding to obtain carbon-loaded pickling mud; transferring the carbon-loaded pickling mud into a chlorination furnace for calcination, and collecting dust and then circulating the flue gas generated in the calcination process through a leaching tower for absorption, and recovering the leaching liquid and the dust-collecting powder; mixing the recovered leaching liquid and the dust-collecting powder, stirring, and performing solid-liquid separation to obtain a liquid part as zinc chloride cobalt enriched liquid; adding an oxidant to the zinc chloride cobalt enriched liquid, stirring, and heating to obtain a zinc oxide cobalt enriched liquid; dripping a sodium hydroxide solution into the zinc oxide cobalt enriched liquid until the pH value is equal to 4-7, aging, and performing solid-liquid separation to obtain a solid part as trivalent cobalt hydroxide, and drying, calcining, and grinding for the third time to obtain cobalt oxide powder. The method can efficiently enrich and recover cobalt resources from purified cobalt slag, realize resource utilization of hazardous wastes, and the solid content of the prepared cobalt oxide is up to 70%. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 A flowchart of a method for recovering cobalt from purified cobalt slag according to an embodiment of the present invention;
[0028] Figure 2 The figure is a schematic flow chart of a method for recovering cobalt from purified cobalt slag according to another embodiment of the present invention. DETAILED DESCRIPTION
[0029] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.
[0030] like Figure 1 and Figure 2 As shown, the present invention proposes a method S100 for recovering cobalt from purified cobalt slag, comprising steps S110 to S170:
[0031] S110, drying the purified cobalt slag, and grinding for 0.5 to 4.5 hours to obtain cobalt slag powder.
[0032] S120, mixing the hydrochloric acid aqueous solution and the cobalt slag powder, stirring, and separating the solid and the liquid, and obtaining the solid part as the pickling mud.
[0033] Specifically, the hydrochloric acid aqueous solution and the cobalt slag powder are mixed at a liquid-solid ratio of 1.5-7.5:1 mL / g, stirred for 0.5-2.5 hours, and the solid-liquid is separated to obtain the solid part as pickling mud, in which the concentration of the hydrochloric acid aqueous solution is 0.5-7.5M.
[0034] In step S120, the hydrochloric acid aqueous solution and the cobalt slag powder are mixed, and during the stirring process, the iron, lead and part of the zinc in the cobalt slag powder are dissolved into the acid solution, while the zinc, cobalt chelate and sulfide are retained in the pickling mud.
[0035] S130, drying the pickling mud, mixing the tar with the dried pickling mud, stirring, and grinding for the second time to obtain the carbon-loaded pickling mud.
[0036] Specifically, the pickling mud is dried, and the tar and the dried pickling mud are mixed in a mass ratio of 2.5 to 7.5:100, stirred evenly, and ground for 0.5 to 1.5 hours to obtain the carbon-loaded pickling mud.
[0037] S140, the carbon-loaded pickling mud is transferred to the chlorination furnace for calcination. The flue gas generated during the calcination process is circulated and absorbed by the leaching tower after the dust is collected, and the leaching liquid and dust collection powder are recovered.
[0038] Specifically, the carbon-loaded pickling mud is transferred to a chlorination furnace for calcination. The flue gas generated during the calcination process is circulated and absorbed by a leaching tower after dust collection, and the leaching liquid and dust collection powder are recovered. The calcination temperature of the chlorination furnace is 650-850°C, the chlorine content is 85%-95%, and the leaching liquid is 0.5-7.5M hydrochloric acid aqueous solution.
[0039] In step S140, tar is mixed with dried pickling mud. During the chlorination process, tar and chelating agent are efficiently carbonized, coordination bonds are broken, and cobalt and zinc are released from the chelating agent. Chlorine dissociates on the surface of tar carbon and chelating agent carbon to generate highly active chlorine atoms. Highly active chlorine atoms react with zinc and cobalt released from the chelating agent on the carbon surface to generate zinc chloride and cobalt chloride gases. In the dust capture and acid leaching stage, zinc chloride and cobalt chloride gases are enriched in the recovered leaching liquid and dust collecting powder.
[0040] S150, the mixed and recovered elution liquid and the dust collecting powder are stirred for 0.5 to 2.5 hours, and the solid-liquid separation is performed to obtain a liquid portion as a zinc-cobalt chloride enriched liquid.
[0041] In step S150, the washing liquid and the dust collecting powder are mixed. During the stirring process, zinc and cobalt are dissolved in the acid solution, and the silicon-based substances have poor solubility and remain in the solid phase. The solid and liquid are separated, thereby achieving the separation of zinc and cobalt from silicon.
[0042] S160, adding an oxidant to the zinc-cobalt chloride enriched solution, stirring and heating to obtain a zinc-cobalt oxide enriched solution.
[0043] Specifically, an oxidant is added to the zinc-cobalt chloride enriched solution at a solid-liquid ratio of 2.5 to 12.5:100 g / mL, and the solution is heated and stirred. After heating and stirring for 0.5 to 2.5 hours, a zinc-cobalt oxide enriched solution is obtained, wherein the heating temperature is 75 to 125° C., and the oxidant is any one of ammonium persulfate or sodium peroxydisulfate.
[0044] In step S160, an oxidant is added to the zinc chloride cobalt enriched solution. During the heating and stirring process, the oxidant is heated to generate sulfate radicals, which can further oxidize the cobalt in the zinc chloride cobalt enriched solution to convert it into trivalent cobalt.
[0045] S170, dripping sodium hydroxide solution into the zinc oxide cobalt enriched solution until the pH value is 4-7, aging for 0.5-1.5 hours, and separating the solid and liquid to obtain the solid part as trivalent cobalt hydroxide, which is dried, calcined, and ground for the third time to obtain cobalt oxide powder.
[0046] In step S170, hydroxide is added to the zinc oxide cobalt enriched solution to adjust the pH, thereby inducing the formation of trivalent cobalt hydroxide, and zinc ions remain in the liquid phase, and the solid and liquid are separated to achieve efficient separation of cobalt and zinc.
[0047] The preparation method of the present invention is simple, and the method can efficiently enrich and recover cobalt resources from purified cobalt slag, thereby realizing resource utilization of hazardous waste. The present invention prepares cobalt oxide from purified cobalt slag by constructing a process of pickling, carbon thermal chlorination, zinc-cobalt enrichment, and cobalt oxidation recovery. The prepared cobalt oxide has a maximum solid content of more than 70%.
[0048] The method for recovering cobalt from purified cobalt slag will be further described below in conjunction with several specific embodiments:
[0049] Example 1
[0050] This example takes the influence of different mass ratios of tar and dried pickling mud on the cobalt content of the prepared cobalt oxide powder as an example to illustrate the method, which includes the following steps:
[0051] S1. Dry the purified cobalt slag and grind it for 0.5 hours to obtain cobalt slag powder.
[0052] S2. Mix the hydrochloric acid aqueous solution and the cobalt slag powder according to a liquid-solid ratio of 1.5 to 7.5:1 mL / g, stir for 0.5 hours, separate the solid and the liquid, and obtain the solid part as pickling mud, in which the concentration of the hydrochloric acid aqueous solution is 0.5 M.
[0053] S3. Dry the pickling mud, mix the tar and the dried pickling mud in mass ratios of 1:100, 1.5:100, 2:100, 2.5:100, 5:100, 7.5:100, 8.5:100, 9.5:100, and 10:100, stir evenly, and grind for 0.5 hour to obtain carbon-loaded pickling mud.
[0054] S4. The carbon-loaded pickling mud is transferred to a chlorination furnace for calcination. The flue gas generated during the calcination process is circulated and absorbed by a leaching tower after dust collection, and the leaching liquid and dust collection powder are recovered. The calcination temperature of the chlorination furnace is 650°C, the chlorine content is 85%, and the leaching liquid is 0.5M hydrochloric acid aqueous solution.
[0055] S5. Mix the recovered washing liquid and dust collecting powder, stir for 0.5 hours, separate the solid and liquid, and obtain the liquid part as the zinc-cobalt chloride enriched liquid.
[0056] S6. Add an oxidant to the zinc-cobalt chloride enriched solution at a solid-liquid ratio of 2.5:100 g / mL, and heat while stirring. After heating and stirring for 0.5 hours, a zinc-cobalt oxide enriched solution is obtained, wherein the heating temperature is 75° C. and the oxidant is ammonium persulfate.
[0057] S7. Add sodium hydroxide solution dropwise to the zinc oxide cobalt enriched solution until the pH is equal to 4, age for 0.5 hours, separate the solid and liquid, and obtain the solid part as trivalent cobalt hydroxide, which is dried, calcined, and ground to obtain cobalt oxide powder.
[0058] Furthermore, the cobalt content of the cobalt oxide powder obtained in Example 1 was tested: the cobalt content of the cobalt oxide powder was tested in accordance with "YS / T 710.1-2009 Chemical Analysis Methods for Cobalt Oxide Part 1: Determination of Cobalt Content". The test results of this example are shown in Table 1.
[0059] Table 1 Effect of the mass ratio of tar to dried pickling mud on the cobalt content of prepared cobalt oxide powder
[0060]
[0061] It can be seen from Table 1 that when the mass ratio of tar to dried pickling mud is less than 2.5:100 (such as in Table 1, the mass ratio of tar to dried pickling mud = 2:100, 1.5:100, 1:100 and lower ratios not listed in Table 1), the amount of tar added is small, and the amount of tar-based carbon generated during the chlorination calcination process is reduced, resulting in a decrease in highly active chlorine atoms and insufficient chlorination of zinc and cobalt, which leads to a significant decrease in the cobalt content of the prepared cobalt oxide powder as the mass ratio of tar to dried pickling mud decreases.
[0062] Furthermore, when the mass ratio of tar to dried pickling mud is equal to 2.5 to 7.5:100 (as in Table 1, the mass ratio of tar to dried pickling mud = 2.5:100, 5:100, 7.5:100), the tar and dried pickling mud are mixed, and the tar and chelating agent are efficiently carbonized during the chlorination process, the coordination bonds are broken, and cobalt and zinc are released from the chelating agent. Chlorine gas dissociates on the surface of tar carbon and chelating agent carbon to generate highly active chlorine atoms. Highly active chlorine atoms react with zinc and cobalt released from the chelating agent on the carbon surface to generate zinc chloride and cobalt chloride gas. Finally, the cobalt content of the prepared cobalt oxide powder is higher than 64%.
[0063] Furthermore, when the mass ratio of tar to dried pickling mud is greater than 7.5:100 (as in Table 1, the mass ratio of tar to dried pickling mud = 8.5:100, 9.5:100, 10:100 and higher ratios not listed in Table 1), excessive tar is added, and too many gas-phase impurities enter the eluent and dust collecting powder during the chlorination calcination process, resulting in the cobalt content of the prepared cobalt oxide powder being significantly reduced as the mass ratio of tar to dried pickling mud further increases.
[0064] Therefore, in general, considering the benefits and costs, when the mass ratio of tar to dried pickling mud is equal to 2.5-7.5:100, it is most conducive to increasing the cobalt content of the prepared cobalt oxide powder.
[0065] Example 2
[0066] This example takes the effect of calcination temperature in a chlorination furnace on the cobalt content of the prepared cobalt oxide powder as an example to illustrate the method, which includes the following steps:
[0067] S1. Dry the purified cobalt slag and grind it for 2.5 hours to obtain cobalt slag powder.
[0068] S2. Mix the hydrochloric acid aqueous solution and the cobalt slag powder at a liquid-solid ratio of 4.5:1 mL / g, stir for 1.5 hours, separate the solid and the liquid, and the solid portion obtained is pickling mud, in which the concentration of the hydrochloric acid aqueous solution is 4M.
[0069] S3. Dry the pickling mud, mix the tar and the dried pickling mud in a mass ratio of 5:100, stir evenly, and grind for 1 hour to obtain carbon-loaded pickling mud.
[0070] S4. The carbon-loaded pickling mud is transferred to a chlorination furnace for calcination. The flue gas generated during the calcination process is circulated and absorbed by a leaching tower after a dust collector, and the leaching liquid and dust collecting powder are recovered. The calcination temperature of the chlorination furnace is 575°C, 600°C, 625°C, 650°C, 750°C, 850°C, 875°C, 900°C, and 925°C. The chlorine content is 90%, and the leaching liquid is 4M hydrochloric acid aqueous solution.
[0071] S5. The recovered washing liquid and dust collecting powder are mixed and stirred for 1.5 hours to separate the solid and liquid, and the obtained liquid part is the zinc cobalt chloride enriched liquid.
[0072] S6. Add an oxidant to the zinc chloride-cobalt enriched solution at a solid-liquid ratio of 7.5:100 g / mL, and heat and stir. After heating and stirring for 1.5 hours, a zinc oxide-cobalt enriched solution is obtained, wherein the heating temperature is 100° C. and the oxidant is ammonium persulfate.
[0073] S7. Add sodium hydroxide solution to the zinc oxide cobalt enriched solution until the pH value is 5.5, age for 1 hour, separate the solid and liquid, and obtain the solid part as trivalent cobalt hydroxide, which is dried, calcined, and ground to obtain cobalt oxide powder.
[0074] Furthermore, the detection of the cobalt content in the cobalt oxide powder in this Example 2 is the same as that in Example 1. The test results of this Example 2 are shown in Table 2.
[0075] Table 2 Effect of calcination temperature in chlorination furnace on the cobalt content of prepared cobalt oxide powder
[0076] Chlorination furnace calcination temperature Cobalt content Relative error 575℃ 57.94％ ±0.1％ 600℃ 61.28％ ±0.1％ 625℃ 64.49％ ±0.1％ 650℃ 68.15％ ±0.1％ 750℃ 68.57％ ±0.1％ 850℃ 69.04％ ±0.1％ 875℃ 66.32％ ±0.1％ 900℃ 64.13％ ±0.2％ 925℃ 60.25％ ±0.2％
[0077] It can be seen from Table 2 that when the calcination temperature of the chlorination furnace is less than 650°C (as in Table 2, the calcination temperature of the chlorination furnace = 625°C, 600°C, 575°C and lower values not listed in Table 2), the calcination temperature of the chlorination furnace is low, the tar carbonization is insufficient, and the amount of chloride gas generated is reduced, resulting in a significant decrease in the cobalt content of the prepared cobalt oxide powder as the calcination temperature of the chlorination furnace decreases.
[0078] Furthermore, when the calcination temperature of the chlorination furnace is equal to 650-850°C (as in Table 2, the calcination temperature of the chlorination furnace = 625°C, 600°C, 575°C), the tar is mixed with the dried pickling mud. During the chlorination process, the tar and the chelating agent are efficiently carbonized, the coordination bonds are broken, and cobalt and zinc are released from the chelating agent. Chlorine gas dissociates on the surface of tar carbon and chelating agent carbon to generate highly active chlorine atoms. Highly active chlorine atoms react with zinc and cobalt released from the chelating agent on the carbon surface to generate zinc chloride and cobalt chloride gases. In the dust capture and acid leaching stage, zinc chloride and cobalt chloride gases are enriched in the recovered leaching solution and dust collecting powder. The leaching solution and the dust collecting powder are mixed, and zinc and cobalt are dissolved in the acid solution during stirring. The silicon-based substance has poor solubility and remains in the solid phase. Solid-liquid separation is performed, thereby achieving the separation of zinc and cobalt from silicon. Finally, the cobalt content of the prepared cobalt oxide powder is higher than 68%.
[0079] Furthermore, when the calcination temperature of the chlorination furnace is greater than 850°C (as in Table 2, the calcination temperature of the chlorination furnace = 875°C, 900°C, 925°C and higher values not listed in Table 2), the calcination temperature is too high, the material loss on ignition increases, and the impurity atmosphere in the flue gas increases significantly, resulting in the cobalt content of the prepared cobalt oxide powder significantly decreasing as the calcination temperature of the chlorination furnace further increases.
[0080] Therefore, in general, considering the benefits and costs, when the calcination temperature of the chlorination furnace is equal to 650-850° C., it is most conducive to increasing the cobalt content of the prepared cobalt oxide powder.
[0081] Example 3
[0082] This example takes the effect of the solid-liquid ratio of the oxidant and the zinc chloride cobalt enriched liquid on the cobalt content of the prepared cobalt oxide powder as an example to illustrate the method, which includes the following steps:
[0083] S1. Dry the purified cobalt slag and grind it for 4.5 hours to obtain cobalt slag powder.
[0084] S2. Mix the hydrochloric acid aqueous solution and the cobalt slag powder according to a liquid-to-solid ratio of 7.5:1 mL / g, stir for 2.5 hours, separate the solid and the liquid, and the solid portion obtained is pickling mud, in which the concentration of the hydrochloric acid aqueous solution is 7.5 M.
[0085] S3. Dry the pickling mud, mix the tar and the dried pickling mud in a mass ratio of 7.5:100, stir evenly, and grind for 1.5 hours to obtain carbon-loaded pickling mud.
[0086] S4. The carbon-loaded pickling mud is transferred to a chlorination furnace for calcination. The flue gas generated during the calcination process is circulated and absorbed by a leaching tower after dust collection, and the leaching liquid and dust collection powder are recovered. The calcination temperature of the chlorination furnace is 850°C, the chlorine content is 95%, and the leaching liquid is 7.5M hydrochloric acid aqueous solution.
[0087] S5. The recovered eluent and dust collecting powder are mixed and stirred for 2.5 hours to separate the solid and liquid, and the obtained liquid portion is a zinc-cobalt chloride enriched solution.
[0088] S6. Add an oxidant to the zinc chloride cobalt enriched solution at a solid-liquid ratio of 1:100 g / mL, 1.5:100 g / mL, 2:100 g / mL, 2.5:100 g / mL, 7.5:100 g / mL, 12.5:100 g / mL, 13.5:100 g / mL, 14.5:100 g / mL, and 15:100 g / mL, and heat with stirring. After heating and stirring for 2.5 hours, a zinc oxide cobalt enriched solution is obtained, wherein the heating temperature is 125° C. and the oxidant is ammonium persulfate.
[0089] S7. Add sodium hydroxide solution to the zinc oxide cobalt enriched solution until the pH is equal to 7, age for 1.5 hours, separate the solid and liquid, and obtain the solid part as trivalent cobalt hydroxide, which is dried, calcined, and ground to obtain cobalt oxide powder.
[0090] Furthermore, the detection of the cobalt content in the cobalt oxide powder in this Example 3 is the same as that in Example 1. The test results of this Example 3 are shown in Table 3.
[0091] Table 3 Effect of solid-liquid ratio of oxidant and zinc chloride cobalt enriched solution on cobalt content of prepared cobalt oxide powder
[0092]
[0093] It can be seen from Table 3 that when the solid-liquid ratio of the oxidant to the zinc-cobalt chloride enriched solution is less than 2.5:100 g / mL (such as in Table 3, the solid-liquid ratio of the oxidant to the zinc-cobalt chloride enriched solution = 2:100 g / mL, 1.5:100 g / mL, 1:100 g / mL and lower values not listed in Table 3),
[0094] Further, when the solid-liquid ratio of the oxidant to the zinc-cobalt chloride enriched solution is equal to 2.5-12.5:100 g / mL (such as in Table 3, the solid-liquid ratio of the oxidant to the zinc-cobalt chloride enriched solution = 2.5:100 g / mL, 7.5:100 g / mL, 12.5:100 g / mL and Table 3), the oxidant is added to the zinc-cobalt chloride enriched solution, and the oxidant is heated to generate sulfate radicals during heating and stirring. The sulfate radicals can further oxidize the cobalt in the zinc-cobalt chloride enriched solution and convert it into trivalent cobalt. Hydroxide is added to adjust the pH, induce the formation of trivalent cobalt hydroxide, and the zinc ions remain in the liquid phase, and the solid-liquid separation is achieved to achieve efficient separation of cobalt and zinc. Finally, the cobalt content of the prepared cobalt oxide powder is higher than 70%.
[0095] Furthermore, when the solid-liquid ratio of the oxidant to the zinc chloride cobalt enriched solution is greater than 12.5:100 g / mL (as in Table 3, the solid-liquid ratio of the oxidant to the zinc chloride cobalt enriched solution = 13.5:100 g / mL, 14.5:100 g / mL, 15:100 g / mL and higher values not listed in Table 3), the oxidant is added in excess, and too many impurities enter the liquid phase, resulting in a significant decrease in the cobalt content of the prepared cobalt oxide powder as the solid-liquid ratio of the oxidant to the zinc chloride cobalt enriched solution further increases.
[0096] Therefore, in general, considering the benefits and costs, when the solid-liquid ratio of the oxidant to the zinc chloride cobalt enriched solution is equal to 2.5-12.5:100 g / mL, it is most conducive to increasing the cobalt content of the prepared cobalt oxide powder.
[0097] Example 4
[0098] This example takes the effect of the solid-liquid ratio of the oxidant and the zinc chloride cobalt enriched liquid on the cobalt content of the prepared cobalt oxide powder as an example to illustrate the method, which includes the following steps:
[0099] S1. Dry the purified cobalt slag and grind it for 4.5 hours to obtain cobalt slag powder.
[0100] S2. Mix the hydrochloric acid aqueous solution and the cobalt slag powder according to a liquid-to-solid ratio of 7.5:1 mL / g, stir for 2.5 hours, separate the solid and the liquid, and the solid portion obtained is pickling mud, in which the concentration of the hydrochloric acid aqueous solution is 7.5 M.
[0101] S3. Dry the pickling mud, mix the tar and the dried pickling mud in a mass ratio of 7.5:100, stir evenly, and grind for 1.5 hours to obtain carbon-loaded pickling mud.
[0102] S4. The carbon-loaded pickling mud is transferred to a chlorination furnace for calcination. The flue gas generated during the calcination process is circulated and absorbed by a leaching tower after dust collection, and the leaching liquid and dust collection powder are recovered. The calcination temperature of the chlorination furnace is 850°C, the chlorine content is 95%, and the leaching liquid is 7.5M hydrochloric acid aqueous solution.
[0103] S5. The recovered eluent and dust collecting powder are mixed and stirred for 2.5 hours to separate the solid and liquid, and the obtained liquid portion is a zinc-cobalt chloride enriched solution.
[0104] S6. Add an oxidant to the zinc chloride-cobalt enriched solution at a solid-liquid ratio of 12.5:100 g / mL, and heat while stirring. After heating and stirring for 2.5 hours, a zinc oxide-cobalt enriched solution is obtained, wherein the heating temperature is 125° C., and the oxidant is any one of ammonium persulfate or sodium peroxydisulfate.
[0105] S7. Add sodium hydroxide solution to the zinc oxide cobalt enriched solution until the pH is equal to 7, age for 1.5 hours, separate the solid and liquid, and obtain the solid part as trivalent cobalt hydroxide, which is dried, calcined, and ground to obtain cobalt oxide powder.
[0106] Furthermore, the detection of the cobalt content in the cobalt oxide powder in this Example 4 is the same as that in Example 1. The test results of this Example 4 are shown in Table 4.
[0107] Table 4 Effect of oxidant type on the cobalt content of prepared cobalt oxide powder
[0108] Oxidant Type Cobalt content Relative error Ammonium Persulfate 70.59％ ±0.1％ Sodium disulfide 70.51％ ±0.1％
[0109] It can be seen from Table 4 that when the oxidant is any one of ammonium persulfate and sodium disulfide, the cobalt content in the obtained cobalt oxide powder is relatively close, which shows that the type of oxidant has little effect on the cobalt content in the prepared cobalt oxide powder.
[0110] The present invention proposes a method for recovering cobalt from purified cobalt slag, which has the following beneficial effects: the method for recovering cobalt is simple, and can efficiently enrich and recover cobalt resources from purified cobalt slag, thereby realizing resource utilization of hazardous waste. The present invention prepares cobalt oxide from purified cobalt slag by constructing a process of pickling, carbon thermal chlorination, zinc-cobalt enrichment, and cobalt oxidation recovery, and the prepared cobalt oxide has a maximum solid content of more than 70%.
[0111] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.
Claims
1. A method for recovering cobalt from purified cobalt slag, characterized in that: The method comprises: The purified cobalt slag is dried and ground for the first time to obtain cobalt slag powder; Mixing the hydrochloric acid aqueous solution and the cobalt slag powder, stirring, and separating the solid from the liquid to obtain pickling mud; The pickling mud is dried, and the tar is mixed with the dried pickling mud, and the mixture is stirred and ground for a second time to obtain carbon-loaded pickling mud; the mass ratio of the tar to the dried pickling mud is 2.5-7.5:100; The carbon-loaded pickling mud is transferred to a chlorination furnace for calcination. The calcination temperature of the chlorination furnace is 650-850° C. The flue gas generated during the calcination process is circulated and absorbed by a leaching tower after dust collection, and the leaching liquid and dust collection powder are recovered; The eluent and the dust collecting powder are mixed, stirred, and solid-liquid separated to obtain a zinc-cobalt chloride enriched solution; Adding an oxidant to the zinc-cobalt chloride enriched solution, stirring, and heating to obtain a zinc-cobalt oxide enriched solution; the solid-liquid ratio of the oxidant to the zinc-cobalt chloride enriched solution is 2.5-12.5:100 g / mL; A sodium hydroxide solution is dripped into the zinc oxide cobalt enriched solution until the pH value is 4-7, aged, and solid-liquid separated to obtain trivalent cobalt hydroxide, which is then dried, calcined, and ground for the third time to obtain cobalt oxide powder.
2. The method according to claim 1, characterized in that The liquid-to-solid ratio of the hydrochloric acid aqueous solution to the cobalt slag powder is 1.5-7.5:1 mL / g.
3. The method according to claim 1, characterized in that The concentration of the hydrochloric acid aqueous solution is 0.5-7.5M.
4. The method according to claim 1, characterized in that: The chlorine content introduced into the chlorination furnace is 85% to 95%; and / or, The eluent is a 0.5-7.5M hydrochloric acid aqueous solution.
5. The method according to claim 1, characterized in that The time range of the first grinding is 0.5 to 4.5 hours; and / or, The time range of the second grinding is 0.5 to 1.5 hours.
6. The method according to claim 1, characterized in that The stirring time ranges from 0.5 to 2.5 hours.
7. The method according to claim 1, characterized in that The heating temperature ranges from 75 to 125°C.
8. The method according to claim 1, characterized in that The aging time ranges from 0.5 to 1.5 hours.