A process for producing high purity metallic cobalt from spent hydrogenation catalyst

Abstract

The present application belongs to the technical field of extracting metal cobalt from waste, and particularly relates to a method for producing high-purity metal cobalt from waste hydrogenation catalyst, which comprises the following steps: (1) roasting and water immersion; (2) acid dissolution and leaching; (3) extraction; (4) vanadium removal; and (5) cobalt electrodeposition to obtain high-purity metal cobalt. The method can obtain high-purity and high-quality metal cobalt.

Description

Technical Field

[0001] The invention belongs to the technical field of extracting metallic cobalt from waste materials, and particularly relates to a method for producing high-purity metallic cobalt from waste hydrogenation catalysts. Background Art

[0002] A catalyst generally refers to a substance that increases the rate of a chemical reaction without altering the chemical equilibrium, and whose mass and chemical properties remain unchanged before and after the reaction. Hydrogenation catalysts are one of the most important catalysts in the petroleum refining process, used for catalytic hydrodesulfurization, denitrogenation, deoxygenation, and demetallization, thereby improving the quality and yield of finished oil products. Hydrogenation catalysts typically use Al2O3 as a carrier, with valuable metals such as nickel and cobalt or their oxides as active components uniformly dispersed on the carrier surface and within its pores. They are widely used in the petroleum refining and chemical industries. After a period of use, they gradually lose their activity due to carbon deposition and metal deposition, resulting in large quantities of hazardous solid waste containing oily substances and heavy metals. During the hydrogenation process, vanadium metal components in residual oil gradually deposit on the catalyst surface. Therefore, spent hydrogenation catalysts typically contain oil, vanadium, nickel, cobalt, and other valuable metals, as well as an alumina carrier. The valuable metals, such as vanadium, nickel, and cobalt, have high recovery value, making their recycling necessary for resource utilization and environmental protection.

[0003] Metallic cobalt can be used as an important raw material for positive electrode materials of lithium-ion batteries in the field of new energy vehicles. It is also widely used in the field of electronic chemicals and the preparation of special alloys. It is an important material for the preparation of magnetic recording, magnetic recording heads, optoelectronic devices, magnetic sensors, integrated circuits and other components. Among them, cobalt with a purity of 99.9% to 99.99% has been widely used in the manufacture of magnetic materials and superalloys, and cobalt with a purity of 99.999% or even higher is used as a target material for advanced electronic components.

[0004] Valuable metal elements in spent hydrogenation catalysts exist in various forms, including oxides, sulfides, salts, and multimetallic complexes, making separation and recovery extremely difficult. CN118308607A discloses a method for recovering vanadium from spent hydrogenation catalysts. The method comprises: uniformly mixing the spent hydrogenation catalyst with a sodium carbonate and sodium aluminate solution, followed by roasting to produce a clinker. The clinker is then leached in an alkaline solution to produce a nickel- and cobalt-rich leached residue and a vanadium-rich sodium aluminate solution. A calcium-containing compound is then added to remove impurities to produce a vanadium-rich solution. Finally, a barium-containing compound is added to the vanadium-rich filtrate to produce a vanadium-containing precipitate for recovery. However, the cobalt in the spent catalyst is not effectively utilized. It can be seen from the multiple embodiments of CN113293297A and other prior art that the vanadium recovery rate can only reach 70-98%, and 2-30% of vanadium still remains in the nickel-cobalt-rich leach residue. It is foreseeable that when conventional processes are used to recover nickel and cobalt from the nickel-cobalt-rich leach residue, this portion of vanadium will be leached, extracted, and stripped along with the nickel and cobalt. When using this vanadium to produce high-purity metallic cobalt, the presence of vanadium will also affect the purity of the metallic cobalt. When high-purity metallic cobalt is produced by electrowinning, even low concentrations of vanadium will have an impact on the electrowinning process. Specifically, vanadium exists in multiple valence states in aqueous solution, and its existence form is easily changed, which easily leads to a significant reduction in current efficiency during electrowinning. When vanadium and cobalt coexist, the electrowinning behavior of vanadium can lead to uneven cobalt metal deposition and cobalt plate stratification, which also reduces the purity of the metallic cobalt. Therefore, when using spent hydrogenation catalyst to recover and prepare high-purity metallic cobalt, deep separation of cobalt and vanadium is very critical. The separation of cobalt and vanadium in the cathode liquid of the electrowinning directly affects the purity and quality of the metallic cobalt. Summary of the Invention

[0005] The present invention aims to solve the above technical problems and provides a method for producing high-purity metallic cobalt from spent hydrogenation catalysts. The method can produce high-purity and high-quality metallic cobalt.

[0006] The technical solution of the present invention is:

[0007] A method for producing high-purity metallic cobalt from spent hydrogenation catalyst comprises the following steps:

[0008] (1) Calcination and water leaching: The spent hydrogenation catalyst is calcined with sodium carbonate and sodium hydroxide under aerobic conditions, cooled naturally, leached with water, and solid-liquid separated to obtain a vanadium-containing leachate and water-leached residue;

[0009] (2) Acid leaching: Acid leaching is performed on the water leaching residue to extract nickel and cobalt. After the leaching is completed, the solid and liquid are separated to obtain a nickel-cobalt solution and acid leaching residue;

[0010] (3) Extraction: Mixing the nickel-cobalt solution with P204 to extract impurities, mixing the P204 raffinate with extractant A to extract cobalt, and obtaining raffinate A and loaded organic phase A; mixing the loaded organic phase A with an inorganic acid solution to strip cobalt, and obtaining a vanadium removal pre-liquid and a stripped organic phase A;

[0011] (4) Vanadium removal: Adjust the pH of the pre-vanadium removal solution to 0-1.5, and then pass it through the pretreated D402 resin for dynamic adsorption of vanadium to obtain the post-vanadium removal solution;

[0012] (5) Cobalt electrolysis: Adjust the pH of the solution after vanadium removal to 1.5-4.0, add boric acid to obtain cathode solution, and electrolyze the cathode solution to obtain high-purity metallic cobalt.

[0013] Preferably, in step (1) of the present invention, the amount of sodium hydroxide used is 1.2-1.5 times the theoretical amount used for the reaction with vanadium and aluminum oxide (calculated based on the reaction of V2O5+6NaOH=2Na3VO4+3H2O, Al2O3+2NaOH=2NaAlO2+H2O), and the amount of sodium carbonate used is 30-60% of the weight of the sodium hydroxide. If the amount of sodium hydroxide used is too little, the vanadium conversion is incomplete, and a large amount of vanadium remains in the leaching residue after water leaching. Therefore, the dissolution of vanadium increases during subsequent acid leaching, and the material is prone to agglomeration after roasting. If the amount of sodium hydroxide used is too much, on the one hand, the sodium hydroxide consumption increases, the material is prone to agglomeration after roasting, and on the other hand, the alkali excess in the subsequent vanadium-containing leachate is high, increasing the recovery cost. If the amount of sodium carbonate used is too little, the material is prone to agglomeration after oxidation roasting, which is not conducive to the subsequent material transfer and water leaching. If the amount of sodium carbonate used is too much, on the one hand, the sodium carbonate consumption increases, and on the other hand, the alkali excess in the nickel-cobalt solution obtained by subsequent water leaching is high, increasing the recovery cost.

[0014] Preferably, in step (1) of the present invention, the calcination method is staged calcination: the first stage calcination temperature is 300-400°C and the time is 1-3 hours. The main purpose of the first stage calcination is to remove oil and oxidize and decompose organic matter in the spent catalyst; the second stage calcination temperature is 600-1000°C and the time is 1-3 hours. The second stage calcination mainly causes the conversion reaction of vanadium and aluminum oxide. The main forms of vanadium in the spent hydrogenation catalyst are vanadium trioxide, vanadium pentoxide, and vanadium sulfide. Nickel and cobalt mainly exist in the form of nickel sulfide, cobalt sulfide, etc., and aluminum exists in the form of aluminum oxide. During calcination, the main function of the added sodium hydroxide is to react with vanadium oxide and aluminum oxide to generate water-soluble sodium metavanadate, sodium vanadate, and sodium metaaluminate solids. Therefore, vanadium and aluminum can be separated from other valuable metals through water leaching and solid-liquid separation. Other valuable metals remain in the water leaching residue and can be further recovered. Adding sodium carbonate during roasting prevents post-calcination agglomeration and extends equipment life. Adding sodium hydroxide alone to the spent hydrogenation catalyst for oxidation roasting easily leads to agglomeration, hindering subsequent material transfer and water leaching. During water leaching, sodium vanadate reacts with water to form water-soluble sodium metavanadate.

[0015] Preferably, in step (1) of the present invention, water is added to a solid content of 20-35 wt.%, the water immersion temperature is 60-95° C., and the time is 1-4 h. After roasting, water immersion is carried out, and heating is beneficial to accelerate the dissolution reaction of the vanadium compound.

[0016] Preferably, in step (2) of the present invention, the pH of the acid dissolution process is controlled at 0.5-1.5 to fully leach the nickel and cobalt in the water leaching residue. When the pH is too high, the nickel and cobalt are not completely leached. When the pH is too low, the amount of inorganic acid used is too large. Heating is conducive to accelerating the acid dissolution and leaching reaction. The acid dissolution time is 1-4 hours and the temperature is 60-95°C. During the acid dissolution, the nickel and cobalt leaching rate is greater than 99%, and the vanadium distribution in the acid leaching residue is 1-8%. The inorganic acid used in the acid dissolution of the present invention is preferably sulfuric acid or hydrochloric acid.

[0017] Preferably, in step (3) of the present invention, the phase ratio of P204 when mixed with impurities for extraction is controlled at 1-2:1, the extractant A is P507 or Cyanex272, and the phase ratio when extracting cobalt is controlled at 1-1.5:1.

[0018] Spent hydrogenation catalysts contain valuable metals such as nickel, cobalt, and vanadium, as well as small amounts of other impurities. The resulting nickel-cobalt solution, obtained after oxidative roasting, water leaching, and acid leaching, contains nickel, cobalt, a small amount of vanadium, and trace amounts of calcium, iron, and aluminum. This nickel-cobalt separation can be achieved through extraction with P204 and extractant A. During this process, small amounts of vanadium are extracted successively by P204 and extractant A. To recover the cobalt, extractant A must be stripped with an inorganic acid. However, during this stripping process, the vanadium carried by extractant A is also stripped along with the cobalt into the vanadium removal pre-solution. Therefore, to produce high-purity metallic cobalt, extensive vanadium removal is necessary. In the nickel-cobalt metallurgy field, P507 and Cyanex272 are commonly used to separate nickel and cobalt from solutions containing nickel and cobalt. Therefore, the extractant A of the present invention is preferably P507 or Cyanex272. By controlling the extraction conditions, cobalt can be extracted while only a small amount of nickel or no nickel is extracted. Nickel is then recovered from the raffinate. The cobalt-loaded organic phase is stripped with an inorganic acid to obtain a cobalt sulfate or cobalt chloride solution, and finally, the cobalt is further recovered. The loaded organic phase A can be stripped of cobalt by inorganic acid, the inorganic acid concentration is preferably 2-4N, and the inorganic acid is preferably sulfuric acid or hydrochloric acid. When stripping cobalt, the cobalt concentration needs to be controlled at 80-110 g / L, and the pH of the outlet aqueous phase is controlled at 2.0-2.5. Before stripping cobalt, the loaded organic phase A needs to be washed with nickel to ensure thorough separation of nickel and cobalt, to prevent a small amount of loaded nickel from entering the vanadium removal pre-liquid along with the cobalt, and to increase the burden of subsequent nickel removal. Inorganic acid is used for nickel washing, preferably with an inorganic acid concentration of 0.5-1.5N, and the pH of the outlet aqueous phase is controlled at 3.0-4.0 to prevent cobalt from being washed together and reducing the cobalt recovery rate.

[0019] D402 resin is a macroporous styrene-based aminophosphonic acid type chelating ion exchange resin, which is mainly used for the adsorption of calcium, magnesium, copper ions, etc. in wastewater treatment to reduce the hardness of wastewater. It can also adsorb a small amount of nickel, cobalt, and other heavy metal ions, and is used for the treatment of wastewater containing low concentrations of nickel, cobalt, and heavy metals. The above adsorption processes are all carried out under neutral or alkaline conditions. The inventors of the present invention have found through multiple experiments that D402 resin can also be used for the adsorption of vanadium under acidic conditions, and the coexisting calcium, magnesium, copper, nickel, and cobalt ions are not adsorbed at this time. Therefore, it can be used for the deep separation of cobalt and vanadium in the present invention, and the liquid after vanadium removal can be further used to produce high-purity metallic cobalt. When pH <2, +5 valence vanadium is mainly in the form of VO2 + The +4 vanadium exists in the form of VO 2+ Vanadium exists in various forms. When the pH is above 2, vanadium with a valence of +5 exists in various forms. When the acidity is lower, vanadium with a valence of +4 also exists in various forms. D402 resin can adsorb both forms of vanadium and is therefore suitable for the deep separation of cobalt and vanadium under acidic conditions in this invention.

[0020] Preferably, in step (4) of the present invention, in order to convert the D402 resin into a hydrogenated form, the pretreatment of the D402 resin is specifically as follows: a mineral acid solution with a mass concentration of 5-10%, preferably hydrochloric acid or sulfuric acid, is dynamically washed at a flow rate of 3-5BV / h, and then the residual acid is washed with pure water at a flow rate of 3-5BV / h. The washing is stopped when the pH at the washing water outlet is 3-4, and the pretreatment is completed.

[0021] When the temperature is too low or the flow rate of the pre-vanadium removal liquid is too fast when D402 resin adsorbs vanadium, the pre-vanadium removal liquid stays in the resin layer for a short time and the contact between the two is insufficient, resulting in a slow adsorption rate and poor adsorption effect. When the temperature is too high, it is not conducive to operation and the energy consumption is high. When the flow rate of the pre-vanadium removal liquid is too slow, the production efficiency is low. Therefore, in step (4) of the present invention, when D402 resin adsorbs vanadium, the adsorption temperature is preferably controlled at 20-40°C, and the flow rate of the pre-vanadium removal liquid is preferably 2-5BV / h.

[0022] Preferably, in step (5) of the present invention, the control conditions for electrolytic cobalt deposition are: electrolytic cell temperature 55-65°C, current density 180-220A / m 2, isopole moment 10-15cm. Increasing the temperature can promote the diffusion of cobalt ions, reduce concentration polarization, reduce the cell voltage, and improve current efficiency. At the same time, increasing the temperature can accelerate the growth rate of cathode deposit grains, making the cathode cobalt crystal particles larger. However, if the temperature is too high, it will increase energy consumption, reduce the hydrogen superpotential, and then increase hydrogen precipitation, reducing current efficiency. When the temperature is too low, it will lead to phenomena such as cathode stratification. The practice of electrolytic cobalt shows that it is preferred to control the temperature of the electrolyte at 55-65°C, which can take into account higher current efficiency, smooth surface of metal cobalt and purity of metal cobalt. The greater the current density, the greater the output. However, as the current density increases, the cell voltage increases and the current efficiency decreases. At the same time, the cathode cobalt surface obtained under high current density is rough and easy to adsorb impurity particles. Therefore, the current density of the present invention is preferably 180-220A / m 2 Using the smallest possible inter-electrode distance is not only beneficial for reducing the cell voltage and improving the current efficiency, but also for increasing the production capacity of the electrolytic cell. However, if the inter-electrode distance is too small, it is easy to increase the contact in the cell and cause short circuits, which will bring many difficulties to the operation and management of the cell surface and reduce the current efficiency. Therefore, the inter-electrode distance of the present invention is preferably 10-15 cm.

[0023] Titanium-iridium-tantalum plates offer excellent electrical conductivity and corrosion resistance, preventing anode corrosive products from entering the cobalt metal cathode. This eliminates the need for a diaphragm for electrolytic deposition. When a cobalt starter sheet is used as the cathode, the present invention eliminates the need for cobalt sheet peeling, reducing labor intensity. Therefore, the present invention preferably utilizes a cobalt starter sheet as the cathode, a titanium-iridium-tantalum plate as the anode, and cobalt electrolytic deposition without a diaphragm.

[0024] When electrolytically depositing cobalt, the present invention adds a certain amount of boric acid to improve the quality of metallic cobalt. During the electrolytic deposition process, the precipitation of cathode hydrogen is inevitable, and the pH value of the electrolyte on the cathode surface increases, which easily leads to the hydrolysis of cobalt ions to form basic salt precipitation adsorbed on the cathode surface, thereby affecting the product quality. When boric acid is added to the electrolyte, since it is a weak acid, there is an ionization equilibrium in the solution. If the pH value of the solution increases, H + , to maintain a stable pH value in the electrolyte. Electrolytic cobalt production practices have shown that excessively high boric acid concentrations reduce cathode current efficiency and are prone to crystallization at low temperatures, resulting in rough, burred surfaces on the electrolytic cobalt plates and waste of raw materials. Therefore, the present invention preferably adds boric acid at a concentration of 6-15 g / L.

[0025] When electrowinning cobalt, the greater the acidity of the cathode liquid (the lower the pH), the more hydrogen ions are deposited at the cathode during the electrowinning process, and the lower the current efficiency. When the pH value of the cathode liquid is high, cobalt hydroxide is easily generated on the cathode, and the produced cathode cobalt has high hardness, poor elasticity, and is easy to stratify. The preferred cathode liquid pH of the present invention is 1.5-4.0.

[0026] In order to reuse the resin, the method of the present invention further includes step (6): desorbing and regenerating the vanadium-loaded resin, using ammonia water with a mass concentration of 2-5% or liquid alkali with a mass concentration of 2-5% during desorption, the temperature during desorption is 20-40°C, and the desorbent flow rate is 1-3BV / h; using an inorganic acid solution with a mass concentration of 5-10%, preferably hydrochloric acid or sulfuric acid, the temperature is 20-40°C, and the inorganic acid solution flow rate is 3-5BV / h during regeneration; before desorption and regeneration, the resin is first washed with pure water, and the regenerated D402 resin can be returned to step (4) for use.

[0027] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0028] 1. The method of the present invention can achieve the separation of nickel, cobalt and vanadium. By deeply adsorbing vanadium with D402 and then performing electrolysis, high-purity metallic cobalt can be obtained, the purity of which can reach above 99.95%. The current efficiency during the electrolysis process reaches above 85%.

[0029] 2. The method of the present invention not only obtains high-purity metallic cobalt, but also has high quality. That is, the surface of the electrolytic cobalt obtained is smooth. The electrolytic deposition time is 5 days and no cobalt plate delamination occurs.

[0030] 3. The method of the present invention can solve the problem of easy agglomeration of the roasted material obtained by oxidative roasting of spent hydrogenation catalyst with sodium hydroxide in the traditional method. The roasting-water leaching process can realize the separation of vanadium and nickel and cobalt in the spent hydrogenation catalyst, laying a good foundation for the subsequent high-purity extraction of metallic cobalt. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention is a flow chart of the method for producing high-purity metallic cobalt from spent hydrogenation catalysts. DETAILED DESCRIPTION

[0032] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0033] Example 1

[0034] A method for producing high-purity metallic cobalt from spent hydrogenation catalyst comprises the following steps:

[0035] (1) Calcination-water leaching: The spent hydrogenation catalyst (nickel 36.5%, cobalt 14.4%, vanadium 2.42%) was calcined with sodium carbonate and sodium hydroxide under aerobic conditions. The calcination conditions were as follows: the amount of sodium hydroxide was 1.5 times the theoretical amount of sodium hydroxide used for reaction with vanadium and alumina (calculated according to the reaction of V2O5+6NaOH=2Na3VO4+3H2O, Al2O3+2NaOH=2NaAlO2+H2O), and the amount of sodium carbonate was 30wt% of the amount of sodium hydroxide used; the calcination method was staged calcination: one stage calcination The sintered product was heated at 300°C for 3 hours, and the second-stage calcination was carried out at 800°C for 2 hours. After the calcination, the product was naturally cooled. No obvious agglomeration was observed in the calcined product. The calcined product was leached with water at a solid content concentration of 20 wt.%, the leaching temperature was 60°C, the leaching time was 4 hours, and the solid-liquid separation was performed to obtain a vanadium-containing leachate and a leaching residue. The nickel-cobalt distribution in the vanadium-containing leachate was less than 0.1%, the vanadium distribution was 97.88%, and the vanadium distribution in the leaching residue was 2.12%. The calcination-water leaching process preliminarily achieved the separation of vanadium from nickel and cobalt in the spent hydrogenation catalyst.

[0036] (2) Acid leaching: The water-leached residue was slurried with water according to a liquid-solid mass ratio of 3:1 ml / g, and a hydrochloric acid solution with a mass concentration of 20% was added for acid dissolution. The pH of the acid dissolution process was controlled to be 1.2, the acid dissolution time was 3 hours, and the temperature was 80°C. The solid and liquid were separated to obtain a nickel-cobalt solution and an acid leaching residue. During the acid dissolution, the nickel-cobalt leaching rate was more than 99%, and the vanadium leaching rate in the acid leaching residue was 75.12% (based on the raw material waste hydrogenation catalyst, the vanadium distribution in the vanadium-containing leachate was 97.88%, the vanadium distribution in the acid leaching residue was 0.53%, and the vanadium distribution in the nickel-cobalt solution was 1.59%).

[0037] (3) Extraction: Mix the nickel-cobalt solution with P204 to extract impurities, and mix the P204 raffinate with P507 to extract cobalt, to obtain a raffinate A and a loaded organic phase A; add 1N hydrochloric acid solution to the loaded organic phase A to wash nickel, control the pH of the wash solution to 3.0, to obtain a nickel-containing wash solution and an organic phase A after nickel washing; mix the organic phase A after nickel washing with 2N hydrochloric acid solution to strip cobalt, control the pH of the strip solution to 2.2, and the cobalt concentration of the strip solution to 80 g / L, to obtain a vanadium removal pre-liquid and an organic phase A after stripping;

[0038] P204 mixed extraction impurity conditions: P204 volume concentration 25%, before extraction, P204 sodium saponification with liquid alkali, saponification rate 50%, after the sodium soap is completed, nickel sulfate solution (nickel concentration 30g / L) is used for nickel soap, saponification temperature is controlled at 40℃, time is 5min, and phase ratio is 1:1.5, so as to remove the sodium ions introduced by the sodium soap. During the extraction of impurities, the temperature is controlled at 40℃, the single-stage extraction time is 5min, the phase ratio is 1.5:1, and the extraction method is countercurrent extraction 4 stages;

[0039] The conditions for the mixed extraction of cobalt with P507 were as follows: P507 concentration was 15% by volume; sodium P507 was saponified with liquid alkali before extraction, with a saponification rate of 60%; the saponification temperature was controlled at 40°C, the extraction time was 5 minutes, and the phase ratio was 1.5:1; the cobalt extraction temperature was controlled at 40°C, the single-stage extraction time was 5 minutes, the phase ratio was 1.5:1, and the extraction method was a 4-stage countercurrent extraction;

[0040] (4) Vanadium removal: hydrochloric acid was added to the pre-vanadium removal solution (vanadium concentration 0.13 g / L) to adjust the pH to 1.0, and then the solution was passed through the pretreated D402 resin for dynamic adsorption of vanadium to obtain the post-vanadium removal solution (vanadium concentration 0.1 mg / L). The adsorption temperature was 20°C and the flow rate of the pre-vanadium removal solution was 2 BV / h.

[0041] D402 resin pretreatment: Dynamically wash with 10% hydrochloric acid solution at a flow rate of 3BV / h, then wash the residual acid with pure water at a flow rate of 3BV / h. Stop washing when the pH of the washing water outlet is 3.0, and the pretreatment process is completed;

[0042] (5) Cobalt electrolysis: add caustic soda to the vanadium-removed solution to adjust the pH to 4.0, add boric acid to obtain a cathode solution, and electrolyze the cathode solution. When electrolyzing cobalt, the cathode is a cobalt starting plate, the anode is a titanium-plated iridium-tantalum plate, and there is no diaphragm electrolysis. Boric acid is added at a dosage of 15g / L. When electrolyzing cobalt, the electrolytic cell temperature is controlled at 55°C and the current density is 180A / m 2 , isopole moment 10cm, obtained high-purity metallic cobalt, purity of 99.98%, the current efficiency of the electrolytic process is 87.91%; the surface of the electrolytic cobalt obtained is flat, the electrolytic time is 5 days, and no cobalt plate delamination occurs;

[0043] (6) Resin desorption and regeneration: First, wash the resin with pure water, then desorb and regenerate the vanadium-loaded resin. During desorption, use ammonia water with a mass concentration of 5% to flow through the vanadium-loaded resin, control the desorption temperature to 20°C, and the desorbent flow rate to 1BV / h. During regeneration, use hydrochloric acid solution with a mass concentration of 10%, and control the hydrochloric acid solution flow rate to 3BV / h. The regenerated D402 resin can be returned to step (4) for use.

[0044] Example 2

[0045] A method for producing high-purity metallic cobalt from spent hydrogenation catalyst comprises the following steps:

[0046] (1) Calcination-water leaching: The spent hydrogenation catalyst (nickel 33.5%, cobalt 20.83%, vanadium 5.42%) was calcined with sodium carbonate and sodium hydroxide under aerobic conditions. The calcination conditions were as follows: the amount of sodium hydroxide was 1.3 times the theoretical amount of sodium hydroxide used for reaction with vanadium and alumina, and the amount of sodium carbonate was 60 wt.% of the amount of sodium hydroxide used. The calcination method was staged calcination: in the first stage, the temperature was kept at 350°C for 2h, and in the second stage, the temperature was kept at 1000°C for 2h. The calcined material was kept at this temperature for 1 hour; after the calcination, it was naturally cooled. No obvious agglomeration was observed in the calcined material. The calcined material was leached with water at a solid content concentration of 35 wt.%, the leaching temperature was 85° C., and the time was 3 hours. The solid-liquid separation was performed to obtain a vanadium-containing leachate and a leaching residue. The nickel and cobalt distribution in the vanadium leachate was less than 0.1%, the vanadium distribution was 95.67%, and the vanadium distribution in the leaching residue was 4.33%. The calcination-water leaching process preliminarily achieved the separation of vanadium from nickel and cobalt in the spent hydrogenation catalyst.

[0047] (2) Acid leaching: The water-leached residue is slurried with water according to a liquid-solid mass ratio of 4:1 ml / g, and sulfuric acid with a mass concentration of 50% is added for acid dissolution. The pH of the acid dissolution process is controlled to be 0.5, the acid dissolution time is 4 hours, and the temperature is 60°C. The solid and liquid are separated to obtain a nickel-cobalt solution and an acid leaching residue. During the acid dissolution, the nickel-cobalt leaching rate is more than 99%, and the vanadium leaching rate in the acid leaching residue is 66.83% (based on the raw material waste hydrogenation catalyst, the vanadium distribution in the vanadium-containing leachate is 95.67%, the vanadium distribution in the acid leaching residue is 1.44%, and the vanadium distribution in the nickel-cobalt solution is 2.89%).

[0048] (3) Extraction: Mix the nickel-cobalt solution with P204 to extract impurities, and mix the P204 raffinate with P507 to extract cobalt, to obtain a raffinate A and a loaded organic phase A; add 0.5N sulfuric acid solution to the loaded organic phase A to wash nickel, and control the pH of the wash solution to be 3.4 to obtain a nickel-containing wash solution and an organic phase A after nickel washing; mix the organic phase A after nickel washing with 4N sulfuric acid solution to strip cobalt, and control the pH of the strip solution to be 2.0, and the cobalt concentration of the strip solution to be 92 g / L, to obtain a vanadium removal pre-liquid and an organic phase A after stripping;

[0049] P204 mixed extraction impurity conditions: P204 volume concentration 18%, before extraction, P204 sodium saponification with liquid alkali, saponification rate 55%, after the sodium soap is completed, nickel sulfate solution (nickel concentration 30g / L) is used for nickel soap, saponification temperature is controlled at 30℃, time is 10min, and phase ratio is 1:2, so as to remove the sodium ions introduced by the sodium soap. During the extraction of impurities, the temperature is controlled at 30℃, the single-stage extraction time is 10min, the phase ratio is 2:1, and the extraction method is countercurrent extraction 4 stages;

[0050] The conditions for the mixed extraction of cobalt with P507 were as follows: P507 concentration of 20% by volume, sodium P507 was saponified with liquid alkali before extraction, with a saponification rate of 55%, the saponification temperature was controlled at 30°C, the extraction time was 10 minutes, and the phase ratio was 1:1. The cobalt extraction was controlled at 30°C, the single-stage extraction time was 10 minutes, the phase ratio was 1:1, and the extraction method was a 4-stage countercurrent extraction.

[0051] (4) Vanadium removal: Sulfuric acid was added to the pre-vanadium removal solution (vanadium concentration 0.58 g / L) to adjust the pH to 0, and then the solution was passed through the pretreated D402 resin for dynamic adsorption of vanadium to obtain a post-vanadium removal solution (vanadium concentration 0.3 mg / L). The adsorption temperature was 30°C and the flow rate of the pre-vanadium removal solution was 5 BV / h.

[0052] D402 resin pretreatment: Dynamically wash with 5% sulfuric acid solution at a flow rate of 5BV / h, then wash the residual acid with pure water at a flow rate of 5BV / h. Stop washing when the pH of the washing water outlet is 4.0, and the pretreatment process is completed;

[0053] (5) Cobalt electrolysis: add caustic soda to the vanadium-removed solution to adjust the pH to 3.0, add boric acid to obtain a cathode solution, and electrolyze the cathode solution. During cobalt electrolysis, the cathode is a cobalt starting plate, the anode is a titanium-plated iridium-tantalum plate, and there is no diaphragm electrolysis. Boric acid is added at a dosage of 10 g / L. When electrolyzing cobalt, the electrolytic cell temperature is controlled at 60 ° C and the current density is 200 A / m 2 , isopole moment 15cm, high-purity metallic cobalt was obtained, with a purity of 99.95%. The current efficiency of the electrolytic process was 85.62%. The surface of the electrolytic cobalt obtained was flat. The electrolytic deposition time was 5 days, and no cobalt plate delamination occurred.

[0054] (6) Resin desorption and regeneration: First, the resin is washed with pure water, and then the vanadium-loaded resin is desorbed and regenerated. During desorption, ammonia water with a mass concentration of 2% is used to flow through the vanadium-loaded resin, and the desorption temperature is controlled to be 30°C and the desorbent flow rate is controlled to be 3BV / h. During regeneration, a sulfuric acid solution with a mass concentration of 5% is used, and the flow rate of the sulfuric acid solution is controlled to be 5BV / h. The regenerated D402 resin can be returned to step (4) for use.

[0055] Example 3

[0056] A method for producing high-purity metallic cobalt from spent hydrogenation catalyst comprises the following steps:

[0057] (1) Calcination-water immersion: The spent hydrogenation catalyst (nickel 40.43%, cobalt 18.90%, vanadium 1.42%) was calcined with sodium carbonate and sodium hydroxide under aerobic conditions. The calcination conditions were as follows: the amount of sodium hydroxide was 1.2 times the theoretical amount of sodium hydroxide used for reaction with vanadium and alumina, and the amount of sodium carbonate was 45% of the amount of sodium hydroxide used. The calcination method was staged calcination: in the first stage, the temperature was kept at 400°C for 1 hour, and in the second stage, the temperature was kept at 600°C for 1 hour. The calcined material was naturally cooled after calcination. No obvious agglomeration was observed in the calcined material. The calcined material was leached with water at a solid content concentration of 30 wt.%, the leaching temperature was 95° C., and the time was 1 hour. The solid-liquid separation was performed to obtain a vanadium-containing leachate and a water-leached residue. The nickel and cobalt distribution in the vanadium-containing leachate was less than 0.1%, the vanadium distribution in the vanadium-containing leachate was 90%, and the vanadium distribution in the water-leached residue was 10%. The calcination-water leaching process preliminarily achieved the separation of vanadium from nickel and cobalt in the spent hydrogenation catalyst.

[0058] (2) Acid leaching: The water leaching residue is slurried with water according to a liquid-solid mass ratio of 5:1, and sulfuric acid with a mass concentration of 98% is added for acid dissolution. The pH of the acid dissolution process is controlled at 1.5, the acid dissolution time is 1 hour, and the temperature is 95°C. The solid and liquid are separated to obtain a nickel-cobalt solution and an acid leaching residue. During the acid dissolution, the nickel-cobalt leaching rate is more than 99%, and the vanadium leaching rate in the acid leaching residue is 75.99% (based on the raw material waste hydrogenation catalyst, the vanadium distribution in the water leaching solution is 90%, the vanadium distribution in the acid leaching residue is 2.40%, and the vanadium distribution in the nickel-cobalt solution is 7.60%).

[0059] (3) Extraction: Mix the nickel-cobalt solution with P204 to extract impurities, and mix the P204 raffinate with Cyanex272 to extract cobalt, to obtain a raffinate A and a loaded organic phase A; add 1.5N sulfuric acid solution to the loaded organic phase A and wash the nickel, controlling the pH of the wash solution to 4.0 to obtain a nickel-containing wash solution and an organic phase A after washing nickel; mix the organic phase A after washing nickel with a 3N sulfuric acid solution to strip cobalt, controlling the pH of the strip solution to 2.5, and the cobalt concentration of the strip solution to 110 g / L, to obtain a vanadium removal pre-liquid and an organic phase A after stripping;

[0060] P204 mixed extraction impurity conditions: P204 volume concentration is 10%, before extraction, P204 is first sodium saponified with liquid alkali, with a saponification rate of 60%, and nickel soap is performed after the sodium soap is completed with nickel sulfate solution (nickel concentration 30g / L). During the saponification, the temperature is controlled at 35°C, the time is 15min, and the phase ratio is 1:1, so as to remove the sodium ions introduced by the sodium soap. During the extraction of impurities, the temperature is controlled at 35°C, the single-stage extraction time is 15min, the phase ratio is 1:1, and the extraction method is countercurrent extraction with 5 stages;

[0061] The conditions for cobalt extraction with Cyanex272 were as follows: Cyanex272 concentration was 15% by volume. Before extraction, sodium Cyanex272 was saponified with liquid alkali to a saponification rate of 50%. The saponification temperature was controlled at 35°C, the extraction time was 15 minutes, and the phase ratio was 1:1. The cobalt extraction was controlled at 35°C, the single-stage extraction time was 15 minutes, the phase ratio was 1:1, and the extraction method was a 5-stage countercurrent extraction.

[0062] (4) Vanadium removal: hydrochloric acid was added to the pre-vanadium removal solution (vanadium concentration 0.35 g / L) to adjust the pH to 1.5, and then the solution was passed through the pretreated D402 resin for dynamic adsorption of vanadium to obtain the post-vanadium removal solution (vanadium concentration 0.2 mg / L). The adsorption temperature was 40°C and the flow rate of the pre-vanadium removal solution was 3 BV / h.

[0063] D402 resin pretreatment: Dynamically wash with 8% sulfuric acid solution at a flow rate of 4BV / h, then wash the residual acid with pure water at a flow rate of 4BV / h. Stop washing when the pH of the washing water outlet is 3.6, and the pretreatment process is completed;

[0064] (5) Cobalt electrolysis: Since the pH of the solution after vanadium removal is 1.5, which is already between 1.5 and 4.0, there is no need to add liquid alkali to adjust the pH. Boric acid is added to the solution after vanadium removal to obtain a cathode solution, which is then electrolyzed. During cobalt electrolysis, the cathode is a cobalt starting plate and the anode is a titanium-plated iridium-tantalum plate. There is no diaphragm electrolysis. Boric acid is added at a dosage of 6 g / L. When electrolyzing cobalt, the electrolytic cell temperature is controlled at 65 ° C and the current density is 220 A / m 2 , isopole moment 12cm, high-purity metallic cobalt was obtained with a purity of 99.97%, the current efficiency of the electrolytic process was 87.70%, the surface of the electrolytic cobalt obtained was flat, the electrolytic time was 5 days, and no cobalt plate delamination occurred;

[0065] (6) Resin desorption and regeneration: First, the resin is washed with pure water, and then the vanadium-loaded resin is desorbed and regenerated. During desorption, a liquid alkali solution with a mass concentration of 5% is passed through the vanadium-loaded resin, and the desorption temperature is controlled at 40°C and the desorbent flow rate is 1BV / h. During regeneration, a sulfuric acid solution with a mass concentration of 8% is used, and the flow rate of the sulfuric acid solution is controlled at 4BV / h. The regenerated D402 resin can be returned to step (4) for use.

[0066] Comparative Example 1

[0067] The vanadium removal pre-liquid (vanadium concentration 0.58 g / L) obtained in step (3) of Example 2 was subjected to activated carbon dynamic degreasing and evaporation crystallization. The activated carbon degreasing conditions were a vanadium removal pre-liquid flow rate of 3 BV / h and a temperature of 35°C. The discharge density during evaporation crystallization was 1.50 g / cm 3 The obtained cobalt sulfate heptahydrate crystals are colorless and have a cobalt content of 20.71%, that is, the purity of the cobalt sulfate heptahydrate crystals is 98.71%.

[0068] The cobalt content of the present invention can be detected by conventional methods. The cobalt purity is calculated by converting the cobalt content into the form of cobalt sulfate heptahydrate crystals. When the purity of cobalt sulfate heptahydrate crystals is 100%, the cobalt content is 20.98%. Based on this, when the cobalt content is 20.71%, the corresponding cobalt sulfate heptahydrate purity is 20.71 / 20.98*100%=98.71%.

[0069] Comparative Example 2

[0070] The vanadium-free solution (vanadium concentration 0.3 mg / L) obtained in step (4) of Example 2 was subjected to evaporation and crystallization under the same conditions as in Comparative Example 1. The obtained cobalt sulfate heptahydrate crystals were free of color and had a purity of 98.76%.

[0071] The data from Comparative Examples 1 and 2, combined with Example 2, demonstrate that within a certain vanadium concentration range, the vanadium concentration has little effect on the appearance quality and purity of the cobalt sulfate heptahydrate crystal product. During crystallization, there is no problem of poor product appearance quality (e.g., discoloration). Commercially available cobalt sulfate heptahydrate is primarily used in battery production, and a cobalt content of 20.5% or greater meets the requirements. Since vanadium does not crystallize with nickel and cobalt during the evaporation crystallization process, it does not affect the purity of the crystal product.

[0072] The requirements for high-purity electrolytic cobalt are different. First, higher cobalt purity is required, as high-purity metallic cobalt has a wider range of applications. Second, the crystallization and electrowinning behaviors of vanadium in cobalt-containing solutions differ significantly, and therefore the depth of vanadium removal from cobalt-containing solutions must also vary. High-purity cobalt sulfate crystals obtained solely through crystallization are insufficient for broader application in terms of product quality and purity. However, the method of Example 2, after vanadium removal, yields metallic cobalt with a purity of 99.95% and high appearance quality. The resulting electrolytic cobalt has a smooth surface and exhibits no cobalt plate delamination after a five-day electrowinning period.

[0073] Comparative Example 3

[0074] The vanadium removal pre-liquid (vanadium concentration 0.58 g / L) obtained in step (3) of Example 2 was electrolytically processed under the same conditions as in Example 2. The surface of the electrolytic cobalt obtained was uneven, and cobalt plate stratification occurred within 24 hours of electrolysis. The cobalt purity was only 98.02%, and the current efficiency was only 76.19%.

[0075] Comparative Example 3 shows that when a cobalt-containing solution without vanadium removal is used to produce metallic cobalt through electrowinning, there are phenomena such as poor product appearance quality, cobalt plate delamination during the electrowinning process, low current efficiency, and lower product purity.

[0076] Comparative Example 4

[0077] The vanadium removal pre-liquid (vanadium concentration 0.58 g / L) obtained in step (3) of Example 2 was subjected to vanadium adsorption using D402 resin. The flow rate of the vanadium removal pre-liquid during adsorption was 6 BV / h, and the remaining vanadium removal conditions were the same as in Example 2. The vanadium concentration of the obtained vanadium removal post-liquid was 0.0053 g / L, indicating incomplete vanadium removal. The vanadium removal post-liquid was then subjected to electrolysis under the same conditions as in Example 2. The surface of the obtained electrolytic cobalt was uneven, and cobalt plate delamination occurred within 24 hours of electrolysis. The cobalt purity was only 98.18%, and the current efficiency was only 78.55%.

[0078] Comparative Example 4 demonstrates that excessively fast vanadium removal by D402 resin, or insufficient vanadium removal depth, can lead to poor product appearance and quality during electrowinning of cobalt metal. Compared to Comparative Examples 1 and 2, the mechanisms by which vanadium influences product quality differ significantly between evaporative crystallization and electrowinning.

[0079] Comparative Example 5

[0080] The vanadium-removed solution obtained in Comparative Example 4 (vanadium concentration: 0.0053 g / L) was subjected to evaporation crystallization under the same conditions as in Comparative Example 1. The obtained cobalt sulfate heptahydrate crystals had no impurities and a purity of 98.76%.

[0081] Comparison Example 4 and Comparative Example 5 both have a vanadium concentration of 0.0053 g / L, but there is no appearance quality problem when used for evaporation crystallization. However, when used for electrolytic production of metallic cobalt, it fails to meet the requirements of high-purity metallic cobalt products. In addition, there are a series of problems such as poor product appearance quality.

[0082] In summary, from Comparative Examples 1-5 and Example 2, it can be seen that when the vanadium-containing cobalt salt solution is subjected to extraction of impurities and extraction and separation of nickel and cobalt, and then evaporated and crystallized to produce cobalt sulfate heptahydrate crystals, a small amount of vanadium does not crystallize together with nickel and cobalt during the evaporation and crystallization process, which does not affect the purity and appearance quality of the crystalline product. Therefore, when producing cobalt sulfate crystal products, the depth of vanadium removal is relatively low. However, in the production process of electrolytic cobalt products, the depth of vanadium removal has a greater impact on the final product, especially the presence of trace vanadium in the process of electrolytic production of high-purity metallic cobalt will affect the purity of metallic cobalt, and vanadium has multiple valence states in the aqueous solution, and its existence form is easy to change, which leads to a very easy reduction in current efficiency during electrolytic production. When vanadium and cobalt coexist, the electrolytic behavior of vanadium can lead to uneven cobalt metal deposition, produce cobalt plate delamination, poor final product appearance quality, and also lead to a reduction in metallic cobalt purity. Therefore, when using spent hydrogenation catalyst to recycle and prepare high-purity metallic cobalt, the depth separation of cobalt and vanadium is the key to the purity, appearance quality, and current efficiency of the electrolytic cobalt that affects metallic cobalt. It can be seen that the synergistic effect of the various steps of the present invention can produce metallic cobalt with high quality and high purity.

[0083] The above description is a detailed description of the preferred embodiments of the present invention, but the embodiments are not intended to limit the scope of the patent application of the present invention. Any equivalent changes or modifications completed under the technical spirit suggested by the present invention should fall within the patent scope covered by the present invention.

Claims

1. A method for producing high-purity metallic cobalt from spent hydrogenation catalyst, characterized in that: The following steps are involved: (1) Calcination and water leaching: The spent hydrogenation catalyst is calcined with sodium carbonate and sodium hydroxide under oxygen conditions, cooled naturally, leached with water, and solid-liquid separated to obtain a vanadium-containing leachate and water-leached residue; wherein the amount of sodium hydroxide used is 1.2-1.5 times the theoretical amount used for its reaction with vanadium and alumina, and the amount of sodium carbonate used is 30-60% of the weight of the sodium hydroxide; the calcination method is staged calcination: the first stage is calcined at a temperature of 300-400°C for a time of 1-3 hours; the second stage is calcined at a temperature of 600-1000°C for a time of 1-3 hours; (2) Acid leaching: Acid leaching is performed on the water leaching residue to extract nickel and cobalt. After the leaching is completed, the solid and liquid are separated to obtain a nickel-cobalt solution and acid leaching residue; (3) Extraction: Mixing the nickel-cobalt solution with P204 to extract impurities, mixing the P204 raffinate with extractant A to extract cobalt, and obtaining a raffinate and a loaded organic phase; mixing the loaded organic phase with an inorganic acid solution to strip cobalt, and obtaining a vanadium removal pre-liquid and a stripped organic phase; wherein the extractant A is P507 or Cyanex272; (4) Vanadium removal: The pH of the pre-vanadium removal solution is adjusted to 0-1.5, and then the solution is passed through the pretreated D402 resin for dynamic adsorption of vanadium to obtain a post-vanadium removal solution; wherein the pretreatment of the D402 resin is specifically as follows: a 5-10% inorganic acid solution is used for dynamic washing at a flow rate of 3-5 BV / h, and then the residual acid is washed with pure water at a flow rate of 3-5 BV / h. When the pH of the washing water outlet is 3-4, the washing is stopped, and the pretreatment is completed; the flow rate of the pre-vanadium removal solution is 2-5 BV / h; (5) Cobalt electrolysis: Adjust the pH of the solution after vanadium removal to 1.5-4.0, add boric acid to obtain cathode solution, and electrolyze the cathode solution to obtain high-purity metallic cobalt.

2. The method for producing high-purity metallic cobalt from spent hydrogenation catalyst according to claim 1, wherein: In the step (1), water is added until the solid content reaches 20-35 wt.%, and the temperature during water immersion is 60-95° C. for 1-4 hours.

3. The method for producing high-purity metallic cobalt from spent hydrogenation catalyst according to claim 1, wherein: In the step (2), the pH value of the acid dissolution process is controlled to be 0.5-1.5, the acid dissolution time is 1-4 hours, and the temperature is 60-95°C.

4. The method for producing high-purity metallic cobalt from spent hydrogenation catalyst according to claim 1, wherein: In the step (3), the ratio of P204 to impurities is controlled to be 1-2:1 when mixed and extracted, and the ratio of P204 to cobalt is controlled to be 1-1.5:1 when extracted.

5. The method for producing high-purity metallic cobalt from spent hydrogenation catalyst according to claim 1, wherein: In the step (3), before stripping cobalt, the loaded organic phase is first washed with nickel. When stripping cobalt, the cobalt concentration of the stripping solution is controlled to be 80-110 g / L.

6. The method for producing high-purity metallic cobalt from spent hydrogenation catalyst according to claim 1, wherein: In the step (4), the adsorption temperature is controlled to be 20-40° C. when the D402 resin adsorbs vanadium.

7. The method for producing high-purity metallic cobalt from spent hydrogenation catalyst according to claim 1, wherein: In the step (5), boric acid is added in an amount of 6-15 g / L, and the control conditions for electrolytic cobalt deposition are: electrolytic cell temperature 55-65 ° C, current density 180-220 A / m 2 , isopole moment 10-15cm.

8. The method for producing high-purity metallic cobalt from spent hydrogenation catalyst according to claim 1, wherein: In the step (5), during the cobalt electrolysis, the cathode is a cobalt starting plate, the anode is a titanium-iridium-tantalum plate, and there is no diaphragm electrolysis.

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