A process for the recovery of copper and nickel from kaldo furnace slag

Abstract

The application discloses a method for recovering copper and nickel from Kaldo furnace slag and belongs to the technical field of metal smelting. The technical route of alkali leaching-pressurized oxidation-acid leaching-neutralization-adsorption separation-ashing reduction is adopted, the alkali leaching reduces the interference of silicon impurities in the subsequent acid leaching system, the pressurized oxidation-acid leaching realizes efficient dissolution of copper and nickel sulfides, the neutralization and iron removal step purifies the leaching solution composition, the composite adsorbent enriches copper and nickel ions, and finally, the copper and nickel mixture is directly obtained through ashing and hydrogen reduction, the process is short, the final product has high value, the whole process chain is complete, the steps are synergistic, and the recovery efficiency and economy are considered.

Description

Technical Field

[0001] This invention relates to the field of metal smelting technology, and more specifically to a method for recovering copper and nickel from Kaldor slag. Background Technology

[0002] Kaldor furnaces are widely used in pyrometallurgical processes for complex copper-nickel materials and secondary resources. These processes produce large quantities of Kaldor slag, which is enriched with valuable metals such as copper and nickel, making it highly valuable for resource recovery. Directly stockpiling or discarding this slag not only leads to a serious waste of these precious metal resources, but also results in the easy leaching of heavy metal ions from the slag by the natural environment, causing severe environmental pollution to soil and groundwater. Therefore, exploring an efficient, clean, and economical copper-nickel recovery technology from Kaldor slag is a crucial issue urgently needing to be addressed in the fields of non-ferrous metallurgy and solid waste purification.

[0003] To recover such valuable metals, various beneficiation processes have been proposed in existing technologies. For example, Chinese patent document CN118698720A discloses a beneficiation method for recovering copper and nickel from nickel-copper Kaldor slag. This method uses a combined process of "grinding-coarse and fine classification-coarse-grained shaking table gravity separation-fine-grained sulfide ore flotation-tailings oxide ore flotation and magnetic separation" to obtain copper concentrate, nickel-copper sulfide concentrate, copper oxide concentrate, and magnetic concentrate, respectively. This process achieves, to a certain extent, the classified recovery and utilization of valuable elements in the slag.

[0004] However, the aforementioned conventional mineral processing technology still faces significant technical bottlenecks in practical applications. Kaldor slag is a special man-made mineral formed by high-temperature melting and cooling. Its copper and nickel phases are mostly embedded in amorphous glassy silicate or fritillary matrix as extremely fine inclusions. This complex mineralogical characteristic makes it difficult for conventional mechanical grinding to achieve sufficient individual liberation of the valuable metal phases. Forcibly increasing the grinding fineness to improve liberation easily leads to mineral mud formation, severely deteriorating the flotation system and rendering conventional reagents ineffective. Therefore, existing methods generally suffer from difficulties in liberating valuable copper and nickel minerals, poor selectivity of flotation reagents, and low overall recovery rates, making it difficult to achieve complete resource utilization of Kaldor slag. Summary of the Invention

[0005] The main objective of this invention is to propose a method for recovering copper and nickel from Kaldor slag. The technical route involves alkaline leaching to reduce interference from silicon impurities in the subsequent acid leaching system, pressurized oxidative acid leaching to achieve efficient dissolution of copper and nickel sulfides, neutralization and iron removal to purify the composition of the leachate, a composite adsorbent to enrich copper and nickel ions, and finally, direct a copper-nickel mixture obtained through ashing and hydrogen reduction. The entire process chain is complete, with each step working synergistically, balancing recovery efficiency and economy. The process is simple, the operating conditions are mild, and the separation efficiency is high.

[0006] To achieve the above objectives, the present invention proposes a method for recovering copper and nickel from Kaldor slag, comprising the following steps: S1. Kaldor slag pretreatment: After crushing the Kaldor slag, water is added and it is ground in a wet ball mill to make a slurry. Alkali solution is added to the slurry for alkali leaching, and the leaching solution and alkali leaching residue are obtained by filtration. S2. Add the alkaline leaching residue to the acid solution for pressurized oxidative leaching, and filter to obtain the acid leaching solution and acid leaching residue; S3. Add an alkaline neutralizing agent to the acid leaching solution to adjust the pH of the system to 3.0-4.0, stir the reaction, filter, separate the filter cake and filtrate, wash the filter cake with water, and combine the washing liquid and filtrate to obtain a neutralized solution. S4: Add composite adsorbent and auxiliary agent to the neutralization solution, stir and react. After the reaction is completed, filter, wash and dry to obtain adsorbent adsorbed with copper and nickel. S5. The adsorbent containing copper and nickel is ashed and then calcined under a hydrogen atmosphere to obtain a copper-nickel mixture.

[0007] Based on the above technical solutions, preferably, in step S2, the acid solution is a sulfuric acid solution, the heating temperature is 140-180℃, the oxygen partial pressure is 0.4-1.0 MPa, and the acid leaching time is 1-3 hours.

[0008] Based on the above technical solutions, preferably, the preparation method of the composite adsorbent in step S4 includes the following steps: (1) After acidification pretreatment of activated carbon with nitric acid, it was mixed with dopamine in Tris-HCl aqueous solution and ultrasonically stirred at room temperature to obtain polydopamine modified activated carbon. (2) Polydopamine-modified activated carbon, 2-aminoimidazolium-4-carboxylic acid, and catalyst 4-dimethylaminopyridine were added to N,N-dimethylformamide for ultrasonic dispersion. Under ice bath conditions, DMF solution of N,N'-dicyclohexylcarbodiimide was added dropwise, followed by heating and reaction. After the reaction was completed, the activated carbon was washed and dried to obtain imidazole-functionalized activated carbon. (3) Imidazole-functionalized activated carbon was dispersed in anhydrous ethanol, eugenol was added, and glacial acetic acid was added dropwise as a catalyst. The mixture was refluxed under N2 protection to obtain a composite adsorbent.

[0009] Based on the above technical solutions, preferably, in step (1), the acidification pretreatment specifically involves adding activated carbon to a nitric acid solution with a mass fraction of 10-20%, stirring at 60-80℃ for 2-4 hours, filtering, washing until neutral, and drying.

[0010] Based on the above technical solutions, preferably, in step (1), the mass ratio of activated carbon to dopamine is 1:(2-4).

[0011] In this step, activated carbon is treated with nitric acid, and then a coating is formed on the surface of carbon nanotubes through the self-polymerization reaction of polydopamine. The oxidation effect of nitric acid can introduce oxygen-containing functional groups such as carboxyl and hydroxyl groups on the surface of activated carbon, which enhances the hydrophilicity and reactivity of the activated carbon surface, reduces the tendency of agglomeration, and promotes the adsorption and uniform coating of polydopamine on the surface of activated carbon.

[0012] Based on the above technical solutions, preferably, in step (2), the mass ratio of the polydopamine-modified activated carbon to 2-aminoimidazole-4-carboxylic acid is 100:8-15; the heating reaction temperature is 50-80℃, and the reaction time is 4-12h.

[0013] In this step, 4-dimethylaminopyridine is used as a catalyst, and N,N'-dicyclohexylcarbodiimide is used to activate the carboxyl group in 2-aminoimidazolium-4-carboxylic acid, enabling it to undergo a highly efficient esterification / amidation coupling reaction with the hydroxyl / amino groups in the polydopamine molecule, introducing an imidazole ring with strong coordination ability. It is worth noting that this step adopts a strategy of slowly adding DCC dropwise after the reactants are co-dispersed under ice bath conditions. Through extremely low initial activator concentration and low temperature control, the occurrence of intermolecular self-condensation side reactions of 2-aminoimidazolium-4-carboxylic acid is effectively suppressed, ensuring the maximization of grafting efficiency and preserving the active primary amino group, which is beneficial to the subsequent Schiff base reaction.

[0014] Based on the above technical solutions, preferably, in step (3), the mass ratio of the imidazole functionalized activated carbon to syringaldehyde is 100:10-20; the reflux reaction temperature is 70-80℃ and the reaction time is 4-6h.

[0015] In this step, the primary amino group retained in step (2) undergoes a Schiff base condensation reaction with the aldehyde group in syringaldehyde to form a stable imine bond, which fixes the syringaldehyde molecule on the material surface. This ultimately endows the composite adsorbent with abundant nitrogen and oxygen heteroatom binding sites, imidazole rings, and phenolic hydroxyl networks, greatly improving the adsorbent's adsorption capacity for copper and nickel.

[0016] Based on the above technical solutions, preferably, the auxiliary agent in step S4 is sodium lauroyl methyl aminopropionate.

[0017] In this step, by adding the amphoteric surfactant sodium lauroyl methyl aminopropionate, its long-chain alkyl groups can be adsorbed onto the surface of the composite adsorbent through hydrophobic interactions, while the hydrophilic amino acid head groups face the solution side, forming an electrostatic barrier on the surface of the adsorbent particles. This effectively inhibits the aggregation of particles caused by hydrophobic interactions and van der Waals forces, allowing the composite adsorbent to maintain a good dispersion state in the solution. This increases the effective contact area between the composite adsorbent and the copper-nickel ion solution, fully exposing the surface coordination groups and improving the actual adsorption capacity of the composite adsorbent.

[0018] Based on the above technical solutions, preferably, the ashing temperature in step S5 is 600-800℃ and the time is 1-2h.

[0019] Based on the above technical solutions, preferably, the calcination temperature in step S5 is 380-420℃ and the time is 0.5-1h.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) This invention provides a novel process for the efficient recovery of copper and nickel from Kaldor slag. The process adopts a technical route of alkaline leaching-pressurized oxidative acid leaching-neutralization-adsorption separation-ashing reduction. Alkaline leaching reduces the interference of silicon impurities in the subsequent acid leaching system. Pressurized oxidative acid leaching achieves efficient dissolution of copper and nickel sulfides. The neutralization and iron removal step purifies the composition of the leaching solution. By adjusting the pH of the system to 3.0-4.0 during the neutralization process, impurity iron can be selectively removed. The composite adsorbent enriches copper and nickel ions. Finally, a copper-nickel mixture is obtained directly through ashing and hydrogen reduction. The process is short and the final product has high value. The entire process chain is complete, and the steps work synergistically, taking into account both recovery efficiency and economy. 2) The preparation of the composite adsorbent of this invention first involves activating activated carbon with acid to introduce oxygen-containing functional groups onto its surface. Then, a polydopamine coating is self-polymerized on its surface, introducing amino and hydroxyl groups as described above. Next, the carboxyl groups in 2-aminoimidazolium-4-carboxylic acid are activated using N,N'-dicyclohexylcarbodiimide, causing them to undergo esterification / amidation coupling reactions with the hydroxyl / amino groups on the polydopamine surface, introducing imidazole ring nitrogen-coordinating groups. These groups are associated with Ni... 2+ It exhibits highly selective chelating ability; finally, through the Schiff base condensation reaction between syringaldehyde and amino groups, a chelating agent for Cu is introduced. 2+ With strong specific coordination ability of imine and o-methoxyphenolic hydroxyl groups, this composite adsorbent exhibits excellent adsorption performance for copper and nickel ions in solution and is easily regenerated through subsequent treatment, significantly improving the purity and efficiency of copper and nickel recovery. Detailed Implementation

[0021] To avoid unnecessary details, unless otherwise specified, all items used in the following examples are commercially available products, and all methods used are conventional methods unless otherwise specified.

[0022] The sources of some of the raw materials used in this invention are as follows: Activated carbon, 100-200 mesh, purchased from Mulinsen Activated Carbon Jiangsu Co., Ltd.

[0023] The raw material used in this embodiment is Kaldor slag produced by the Guixi Smelter of Jiangxi Copper Industry. According to the analysis, the mass fraction of copper in its composition is 2.5%, the mass fraction of nickel is 1.8%, and copper and nickel mainly exist in the form of sulfides; among the associated impurities, the mass fraction of iron is 8.0%, and the mass fraction of silicon is 12.0%.

[0024] Example 1

[0025] A method for recovering copper and nickel from Kaldor slag includes the following steps: S1. Place 1 kg of Kaldor slag in a jaw crusher and crush it to a particle size ≤ 5 mm. Then add 2000 mL of deionized water and grind it in a wet ball mill for 60 min to obtain a slurry with a solid content of about 30 wt% and a particle size D90 ≤ 74 μm. Add 1500 mL of 15 wt% NaOH solution to the slurry and stir and leach it at 90 °C for 2 h. After leaching, filter it while it is hot and wash the filter cake three times with deionized water. Combine the filtrate and washing liquid to obtain leaching solution and leaching residue. S2. Transfer the alkaline leaching residue to a titanium alloy autoclave, add 1500 mL of 15wt% sulfuric acid solution (liquid-solid ratio approximately 5:1 mL / g), seal the autoclave, introduce high-purity oxygen, control the oxygen partial pressure at 0.6 MPa, raise the temperature to 160℃, and leach for 2 hours with constant temperature stirring; after the reaction is complete, stop heating, and release the pressure after the temperature inside the autoclave drops below 80℃. Transfer the slurry inside the autoclave to a Buchner funnel and filter while hot. Wash the filter cake three times with 80℃ hot deionized water, combine the filtrate and washing liquid to obtain acid leaching solution and acid leaching residue. S3. Add a 15wt% sodium hydroxide aqueous solution dropwise to the acid leaching solution obtained in step S2 at a rate of 2 mL / min, monitoring the pH in real time with a pH meter. Stop adding the alkali solution when the pH of the system rises to 3.5. Continue stirring the reaction at 60℃ for 1 hour. Under these conditions, Fe... 3+ The solution is completely precipitated as Fe(OH)3. After the reaction is complete, the solution is filtered while hot to separate the filtrate and the filter cake. The filter cake is washed multiple times with deionized water at 60℃, and the washing liquid and filtrate are combined to obtain a neutralized solution. S4. Add 340g of composite adsorbent to 5000mL of neutralization solution, then add 10.2g of sodium lauroyl methyl aminopropionate, stir and react at 50℃ for 3h. After the reaction is completed, filter, collect the filter cake, wash the filter cake with deionized water until the washing liquid is clear, and then dry to obtain the adsorbent adsorbed with copper and nickel. S5. The adsorbent containing copper and nickel was transferred to an alumina crucible and placed in a muffle furnace. The temperature was increased to 700°C at a rate of 5°C / min under air atmosphere and ashed for 1.5 h to completely oxidize and decompose the organic carrier. After cooling, the ashed product was obtained, mainly composed of CuO, NiO, and a small amount of residual inorganic matter. The ashed product was transferred to a tube furnace, and high-purity H2 (flow rate 200 mL / min) was introduced. The temperature was increased to 400°C at a rate of 5°C / min and reduced under H2 atmosphere for 0.8 h. After reduction, the mixture was naturally cooled to room temperature under H2 atmosphere protection to obtain a copper-nickel mixture.

[0026] The preparation method of the composite adsorbent includes the following steps: (1) Weigh 100g of coconut shell activated carbon, add it to 500 mL of 15wt% nitric acid solution, and stir magnetically at 70℃ for 3h to fully oxidize the surface of the activated carbon. After the reaction is completed, filter it and wash it repeatedly with deionized water until the filtrate is neutral. Dry it in an oven at 80℃ for 12h and then add it to 4000 mL of Tris-HCl aqueous solution with pH 9. Mix it and stir ultrasonically at room temperature for 20h. The reaction product is separated by centrifugation, washed and vacuum dried to obtain polydopamine modified activated carbon. (2) Weigh 100g of polydopamine-modified activated carbon, 10g of 2-aminoimidazolium-4-carboxylic acid, and 1.0g of catalyst 4-dimethylaminopyridine and add them to 1000mL of N,N-dimethylformamide for ultrasonic dispersion. Under ice bath conditions, slowly add DMF solution containing 19.5g of 0.5g / mL N,N'-dicyclohexylcarbodiimide. Then heat the reaction at 60℃ for 8h. After the reaction is completed, filter and collect the solid. Wash it several times with N,N-dimethylformamide and anhydrous ethanol. Then dry it under vacuum to obtain imidazole-functionalized activated carbon. (3) Weigh 100g of imidazole-functionalized activated carbon and add it to 600mL of anhydrous ethanol. Disperse it by sonication for 15min. Add 15g of eugenol and stir to dissolve. Then slowly add 0.5mL of glacial acetic acid as a catalyst. Pour N2 for protection and heat to 75℃ for reflux reaction for 5h. After cooling, filter and wash with anhydrous ethanol and deionized water 3 times each. Dry in an oven at 80℃ for 12h to obtain the composite adsorbent.

[0027] Example 2

[0028] A method for recovering copper and nickel from Kaldor slag includes the following steps: S1. Place 1 kg of Kaldor slag in a jaw crusher and crush it to a particle size ≤ 5 mm. Then add 2000 mL of deionized water and grind it in a wet ball mill for 60 min to obtain a slurry with a solid content of about 30 wt% and a particle size D90 ≤ 74 μm. Add 1500 mL of 15 wt% NaOH solution to the slurry and stir and leach it at 90 °C for 2 h. After leaching, filter it while it is hot and wash the filter cake three times with deionized water. Combine the filtrate and washing liquid to obtain leaching solution and leaching residue. S2. Transfer the alkaline leaching residue to a titanium alloy autoclave, add 1500 mL of 15wt% sulfuric acid solution (liquid-solid ratio approximately 5:1 mL / g), seal the autoclave, introduce high-purity oxygen, control the oxygen partial pressure at 0.4 MPa, raise the temperature to 140℃, and leach for 1 hour with constant temperature stirring; after the reaction is complete, stop heating, and release the pressure after the temperature inside the autoclave drops below 80℃. Transfer the slurry inside the autoclave to a Buchner funnel and filter while hot. Wash the filter cake three times with 80℃ hot deionized water, combine the filtrate and washing liquid to obtain acid leaching solution and acid leaching residue. S3. Add a 15wt% sodium hydroxide aqueous solution dropwise to the acid leaching solution obtained in step S2 at a rate of 2 mL / min, monitoring the pH in real time with a pH meter. Stop adding the alkali solution when the pH of the system rises to 3. Continue stirring the reaction at 60℃ for 1 h. Under these conditions, Fe 3+ The solution is completely precipitated as Fe(OH)3. After the reaction is complete, the solution is filtered while hot to separate the filtrate and the filter cake. The filter cake is washed multiple times with deionized water at 60℃, and the washing liquid and filtrate are combined to obtain a neutralized solution. S4. Add 340g of composite adsorbent to 5000mL of neutralization solution, then add 6.8g of sodium lauroyl methyl aminopropionate, stir and react at 50℃ for 3h, filter after the reaction is completed, collect the filter cake, wash the filter cake with deionized water until the washing liquid is clear, and then dry to obtain the adsorbent adsorbed with copper and nickel. S5. The adsorbent containing copper and nickel was transferred to an alumina crucible and placed in a muffle furnace. The temperature was increased to 600°C at a rate of 5°C / min under air atmosphere and ashed for 1 hour to completely oxidize and decompose the organic support. After cooling, the ashed product was obtained, mainly composed of CuO, NiO, and a small amount of residual inorganic matter. The ashed product was transferred to a tube furnace, and high-purity H2 (flow rate 200 mL / min) was introduced. The temperature was increased to 380°C at a rate of 5°C / min and reduced under H2 atmosphere for 0.8 hours. After reduction, the mixture was naturally cooled to room temperature under H2 atmosphere protection to obtain a copper-nickel mixture.

[0029] The preparation method of the composite adsorbent includes the following steps: (1) Weigh 100g of coconut shell activated carbon, add it to 500 mL of 15wt% nitric acid solution, and stir magnetically at 70℃ for 3h to fully oxidize the surface of the activated carbon. After the reaction is completed, filter it and wash it repeatedly with deionized water until the filtrate is neutral. Dry it in an oven at 80℃ for 12h and then add it to 4000 mL of Tris-HCl aqueous solution with pH 9. Mix it and stir ultrasonically at room temperature for 20h. The reaction product is separated by centrifugation, washed and vacuum dried to obtain polydopamine modified activated carbon. (2) Weigh 100g of polydopamine-modified activated carbon, 8g of 2-aminoimidazolium-4-carboxylic acid, and 0.8g of catalyst 4-dimethylaminopyridine and add them to 1000mL of N,N-dimethylformamide for ultrasonic dispersion. Under ice bath conditions, slowly add DMF solution containing 19.5g of 0.5g / mL N,N'-dicyclohexylcarbodiimide. Then heat the reaction at 50℃ for 12h. After the reaction is completed, filter and collect the solid. Wash it several times with N,N-dimethylformamide and anhydrous ethanol. Then dry it under vacuum to obtain imidazole-functionalized activated carbon. (3) Weigh 100g of imidazole-functionalized activated carbon and add it to 600mL of anhydrous ethanol. Disperse it by ultrasonication for 15min. Add 10g of eugenol and stir to dissolve. Then slowly add 0.5mL of glacial acetic acid as a catalyst. Pour N2 for protection and heat to 75℃ for reflux reaction for 5h. After cooling, filter and wash with anhydrous ethanol and deionized water 3 times each. Dry in an oven at 80℃ for 12h to obtain the composite adsorbent.

[0030] Example 3

[0031] A method for recovering copper and nickel from Kaldor slag includes the following steps: S1. Place 1 kg of Kaldor slag in a jaw crusher and crush it to a particle size ≤ 5 mm. Then add 2000 mL of deionized water and grind it in a wet ball mill for 60 min to obtain a slurry with a solid content of about 30 wt% and a particle size D90 ≤ 74 μm. Add 1500 mL of 15 wt% NaOH solution to the slurry and stir and leach it at 90 °C for 2 h. After leaching, filter it while it is hot and wash the filter cake three times with deionized water. Combine the filtrate and washing liquid to obtain leaching solution and leaching residue. S2. Transfer the alkaline leaching residue to a titanium alloy autoclave, add 1500 mL of 15wt% sulfuric acid solution (liquid-solid ratio approximately 5:1 mL / g), seal the autoclave, introduce high-purity oxygen, control the oxygen partial pressure at 1.0 MPa, raise the temperature to 180℃, and leach for 2 hours with constant temperature stirring; after the reaction is complete, stop heating, and release the pressure after the temperature inside the autoclave drops below 80℃. Transfer the slurry inside the autoclave to a Buchner funnel and filter while hot. Wash the filter cake three times with 80℃ hot deionized water, combine the filtrate and washing liquid to obtain acid leaching solution and acid leaching residue; S3. Add a 15wt% sodium hydroxide aqueous solution dropwise to the acid leaching solution obtained in step S2 at a rate of 2mL / min, monitoring the pH in real time with a pH meter. Stop adding the alkali solution when the pH of the system rises to 4. Continue stirring the reaction at 60℃ for 1h. Under these conditions, Fe 3+ The solution is completely precipitated as Fe(OH)3. After the reaction is complete, the solution is filtered while hot to separate the filtrate and the filter cake. The filter cake is washed multiple times with deionized water at 60℃, and the washing liquid and filtrate are combined to obtain a neutralized solution. S4. Add 340g of composite adsorbent to 5000mL of neutralization solution, then add 17g of sodium lauroyl methyl aminopropionate, stir and react at 50℃ for 3h, filter after the reaction is completed, collect the filter cake, wash the filter cake with deionized water until the washing liquid is clear, and then dry to obtain the adsorbent adsorbed with copper and nickel. S5. The adsorbent containing copper and nickel was transferred to an alumina crucible and placed in a muffle furnace. The temperature was increased to 800°C at a rate of 5°C / min under air atmosphere and ashed for 2 hours to completely oxidize and decompose the organic carrier. After cooling, the ashed product was obtained, mainly composed of CuO, NiO, and a small amount of residual inorganic matter. The ashed product was transferred to a tube furnace, and high-purity H2 (flow rate 200 mL / min) was introduced. The temperature was increased to 420°C at a rate of 5°C / min and reduced under H2 atmosphere for 1 hour. After reduction, the mixture was naturally cooled to room temperature under H2 atmosphere protection to obtain a copper-nickel mixture.

[0032] The preparation method of the composite adsorbent includes the following steps: (1) Weigh 100g of coconut shell activated carbon, add it to 500 mL of 15wt% nitric acid solution, and stir magnetically at 70℃ for 3h to fully oxidize the surface of the activated carbon. After the reaction is completed, filter it and wash it repeatedly with deionized water until the filtrate is neutral. Dry it in an oven at 80℃ for 12h and then add it to 4000mL of Tris-HCl aqueous solution with pH 9. Mix it and stir it ultrasonically at room temperature for 20h. The reaction product is separated by centrifugation, washed and vacuum dried to obtain polydopamine modified activated carbon. (2) Weigh 100g of polydopamine-modified activated carbon, 15g of 2-aminoimidazolium-4-carboxylic acid, and 1.5g of catalyst 4-dimethylaminopyridine and add them to 1000mL of N,N-dimethylformamide for ultrasonic dispersion. Under ice bath conditions, slowly add DMF solution containing 22.6g of 0.5g / mL N,N'-dicyclohexylcarbodiimide. Then heat the reaction at 80℃ for 4h. After the reaction is completed, filter and collect the solid. Wash it several times with N,N-dimethylformamide and anhydrous ethanol. Then dry it under vacuum to obtain imidazole-functionalized activated carbon. (3) Weigh 100g of imidazole-functionalized activated carbon and add it to 600mL of anhydrous ethanol. Disperse it by ultrasonication for 15min. Add 10g of eugenol and stir to dissolve. Then slowly add 0.5mL of glacial acetic acid as a catalyst. Pour N2 for protection and heat to 75℃ for reflux reaction for 5h. After cooling, filter and wash with anhydrous ethanol and deionized water 3 times each. Dry in an oven at 80℃ for 12h to obtain the composite adsorbent.

[0033] Comparative Example 1 A method for recovering copper and nickel from Kaldor slag includes the following steps: S1. Place 1 kg of Kaldor slag in a jaw crusher and crush it to a particle size ≤ 5 mm. Then add 2000 mL of deionized water and grind it in a wet ball mill for 60 min to obtain a slurry with a solid content of about 30 wt% and a particle size D90 ≤ 74 μm. Add 1500 mL of 15 wt% NaOH solution to the slurry and stir and leach it at 90 °C for 2 h. After leaching, filter it while it is hot and wash the filter cake three times with deionized water. Combine the filtrate and washing liquid to obtain leaching solution and leaching residue. S2. Transfer the alkaline leaching residue to a titanium alloy autoclave, add 1500 mL of 15wt% sulfuric acid solution (liquid-solid ratio approximately 5:1 mL / g), seal the autoclave, introduce high-purity oxygen, control the oxygen partial pressure at 0.6 MPa, raise the temperature to 160℃, and leach for 2 hours with constant temperature stirring; after the reaction is complete, stop heating, and release the pressure after the temperature inside the autoclave drops below 80℃. Transfer the slurry inside the autoclave to a Buchner funnel and filter while hot. Wash the filter cake three times with 80℃ hot deionized water, combine the filtrate and washing liquid to obtain acid leaching solution and acid leaching residue. S3. Add a 15wt% sodium hydroxide aqueous solution dropwise to the acid leaching solution obtained in step S2 at a rate of 2 mL / min, monitoring the pH in real time with a pH meter. Stop adding the alkali solution when the pH of the system rises to 3.5. Continue stirring the reaction at 60℃ for 1 hour. Under these conditions, Fe... 3+ The solution is completely precipitated as Fe(OH)3. After the reaction is complete, the solution is filtered while hot to separate the filtrate and the filter cake. The filter cake is washed multiple times with deionized water at 60℃, and the washing liquid and filtrate are combined to obtain a neutralized solution. S4. Add 340g of composite adsorbent to 5000mL of neutralization solution, stir and react at 50℃ for 3h. After the reaction is completed, filter, collect the filter cake, wash the filter cake with deionized water until the washing liquid is clear, and then dry to obtain the adsorbent adsorbed with copper and nickel. S5. The adsorbent containing copper and nickel was transferred to an alumina crucible and placed in a muffle furnace. The temperature was increased to 700°C at a rate of 5°C / min under air atmosphere and ashed for 1.5 h to completely oxidize and decompose the organic carrier. After cooling, the ashed product was obtained, mainly composed of CuO, NiO, and a small amount of residual inorganic matter. The ashed product was transferred to a tube furnace, and high-purity H2 (flow rate 200 mL / min) was introduced. The temperature was increased to 400°C at a rate of 5°C / min and reduced under H2 atmosphere for 0.8 h. After reduction, the mixture was naturally cooled to room temperature under H2 atmosphere protection to obtain a copper-nickel mixture.

[0034] The preparation method of the composite adsorbent includes the following steps: (1) Weigh 100g of coconut shell activated carbon, add it to 500 mL of 15wt% nitric acid solution, and stir magnetically at 70℃ for 3h to fully oxidize the surface of the activated carbon. After the reaction is completed, filter it and wash it repeatedly with deionized water until the filtrate is neutral. Dry it in an oven at 80℃ for 12h and then add it to 4000 mL of Tris-HCl aqueous solution with pH 9. Mix it and stir ultrasonically at room temperature for 20h. The reaction product is separated by centrifugation, washed and vacuum dried to obtain polydopamine modified activated carbon. (2) Weigh 100g of polydopamine-modified activated carbon, 10g of 2-aminoimidazolium-4-carboxylic acid, and 1.0g of catalyst 4-dimethylaminopyridine and add them to 1000mL of N,N-dimethylformamide for ultrasonic dispersion. Under ice bath conditions, slowly add DMF solution containing 19.5g of 0.5g / mL N,N'-dicyclohexylcarbodiimide. Then heat the reaction at 60℃ for 8h. After the reaction is completed, filter and collect the solid. Wash it several times with N,N-dimethylformamide and anhydrous ethanol. Then dry it under vacuum to obtain imidazole-functionalized activated carbon. (3) Weigh 100g of imidazole-functionalized activated carbon and add it to 600mL of anhydrous ethanol. Disperse it by sonication for 15min. Add 15g of eugenol and stir to dissolve. Then slowly add 0.5mL of glacial acetic acid as a catalyst. Pour N2 for protection and heat to 75℃ for reflux reaction for 5h. After cooling, filter and wash with anhydrous ethanol and deionized water 3 times each. Dry in an oven at 80℃ for 12h to obtain the composite adsorbent.

[0035] This comparative example is similar to Example 1, except that sodium lauroyl methyl aminopropionate was not added in step S4.

[0036] Comparative Example 2 A method for recovering copper and nickel from Kaldor slag includes the following steps: S1. Place 1 kg of Kaldor slag in a jaw crusher and crush it to a particle size ≤ 5 mm. Then add 2000 mL of deionized water and grind it in a wet ball mill for 60 min to obtain a slurry with a solid content of about 30 wt% and a particle size D90 ≤ 74 μm. Add 1500 mL of 15 wt% NaOH solution to the slurry and stir and leach it at 90 °C for 2 h. After leaching, filter it while it is hot and wash the filter cake three times with deionized water. Combine the filtrate and washing liquid to obtain leaching solution and leaching residue. S2. Transfer the alkaline leaching residue to a titanium alloy autoclave, add 1500 mL of 15wt% sulfuric acid solution (liquid-solid ratio approximately 5:1 mL / g), seal the autoclave, introduce high-purity oxygen, control the oxygen partial pressure at 0.6 MPa, raise the temperature to 160℃, and leach for 2 hours with constant temperature stirring; after the reaction is complete, stop heating, and release the pressure after the temperature inside the autoclave drops below 80℃. Transfer the slurry inside the autoclave to a Buchner funnel and filter while hot. Wash the filter cake three times with 80℃ hot deionized water, combine the filtrate and washing liquid to obtain acid leaching solution and acid leaching residue. S3. Add a 15wt% sodium hydroxide aqueous solution dropwise to the acid leaching solution obtained in step S2 at a rate of 2 mL / min, monitoring the pH in real time with a pH meter. Stop adding the alkali solution when the pH of the system rises to 3.5. Continue stirring the reaction at 60℃ for 1 hour. Under these conditions, Fe... 3+ The solution is completely precipitated as Fe(OH)3. After the reaction is complete, the solution is filtered while hot to separate the filtrate and the filter cake. The filter cake is washed multiple times with deionized water at 60℃, and the washing liquid and filtrate are combined to obtain a neutralized solution. S4. Add 340g of composite adsorbent to 5000mL of neutralization solution, then add 10.2g of sodium lauroyl methyl aminopropionate, stir and react at 50℃ for 3h. After the reaction is completed, filter, collect the filter cake, wash the filter cake with deionized water until the washing liquid is clear, and then dry to obtain the adsorbent adsorbed with copper and nickel. S5. The adsorbent containing copper and nickel was transferred to an alumina crucible and placed in a muffle furnace. The temperature was increased to 700°C at a rate of 5°C / min under air atmosphere and ashed for 1.5 h to completely oxidize and decompose the organic carrier. After cooling, the ashed product was obtained, mainly composed of CuO, NiO, and a small amount of residual inorganic matter. The ashed product was transferred to a tube furnace, and high-purity H2 (flow rate 200 mL / min) was introduced. The temperature was increased to 400°C at a rate of 5°C / min and reduced under H2 atmosphere for 0.8 h. After reduction, the mixture was naturally cooled to room temperature under H2 atmosphere protection to obtain a copper-nickel mixture.

[0037] The preparation method of the composite adsorbent includes the following steps: (1) Weigh 100g of coconut shell activated carbon, add it to 500 mL of 15wt% nitric acid solution, and stir magnetically at 70℃ for 3h to fully oxidize the surface of the activated carbon. After the reaction is completed, filter it and wash it repeatedly with deionized water until the filtrate is neutral. Dry it in an oven at 80℃ for 12h and then add it to 4000 mL of Tris-HCl aqueous solution with pH 9. Mix it and stir ultrasonically at room temperature for 20h. The reaction product is separated by centrifugation, washed and vacuum dried to obtain polydopamine modified activated carbon. (2) Weigh 100g of polydopamine-modified activated carbon, 10g of 2-aminoimidazolium-4-carboxylic acid, and 1.0g of catalyst 4-dimethylaminopyridine and add them to 1000mL of N,N-dimethylformamide for ultrasonic dispersion. Under ice bath conditions, slowly add DMF solution containing 19.5g of 0.5g / mL N,N'-dicyclohexylcarbodiimide. Then heat the reaction at 60℃ for 8h. After the reaction is completed, filter and collect the solid. Wash it several times with N,N-dimethylformamide and anhydrous ethanol, and then vacuum dry to obtain the composite adsorbent.

[0038] This comparative example is similar to Example 1, except that syringaldehyde was not added during the preparation of the composite adsorbent.

[0039] Comparative Example 3 A method for recovering copper and nickel from Kaldor slag includes the following steps: S1. Place 1 kg of Kaldor slag in a jaw crusher and crush it to a particle size ≤ 5 mm. Then add 2000 mL of deionized water and grind it in a wet ball mill for 60 min to obtain a slurry with a solid content of about 30 wt% and a particle size D90 ≤ 74 μm. Add 1500 mL of 15 wt% NaOH solution to the slurry and stir and leach it at 90 °C for 2 h. After leaching, filter it while it is hot and wash the filter cake three times with deionized water. Combine the filtrate and washing liquid to obtain leaching solution and leaching residue. S2. Transfer the alkaline leaching residue to a titanium alloy autoclave, add 1500 mL of 15wt% sulfuric acid solution (liquid-solid ratio approximately 5:1 mL / g), seal the autoclave, introduce high-purity oxygen, control the oxygen partial pressure at 0.6 MPa, raise the temperature to 160℃, and leach for 2 hours with constant temperature stirring; after the reaction is complete, stop heating, and release the pressure after the temperature inside the autoclave drops below 80℃. Transfer the slurry inside the autoclave to a Buchner funnel and filter while hot. Wash the filter cake three times with 80℃ hot deionized water, combine the filtrate and washing liquid to obtain acid leaching solution and acid leaching residue. S3. Add a 15wt% sodium hydroxide aqueous solution dropwise to the acid leaching solution obtained in step S2 at a rate of 2 mL / min, monitoring the pH in real time with a pH meter. Stop adding the alkali solution when the pH of the system rises to 3.5. Continue stirring the reaction at 60℃ for 1 hour. Under these conditions, Fe... 3+The solution is completely precipitated as Fe(OH)3. After the reaction is complete, the solution is filtered while hot to separate the filtrate and the filter cake. The filter cake is washed multiple times with deionized water at 60℃, and the washing liquid and filtrate are combined to obtain a neutralized solution. S4. Add 340g of composite adsorbent to 5000mL of neutralization solution, then add 10.2g of sodium lauroyl methyl aminopropionate, stir and react at 50℃ for 3h. After the reaction is completed, filter, collect the filter cake, wash the filter cake with deionized water until the washing liquid is clear, and then dry to obtain the adsorbent adsorbed with copper and nickel. S5. The adsorbent containing copper and nickel was transferred to an alumina crucible and placed in a muffle furnace. The temperature was increased to 700°C at a rate of 5°C / min under air atmosphere and ashed for 1.5 h to completely oxidize and decompose the organic carrier. After cooling, the ashed product was obtained, mainly composed of CuO, NiO, and a small amount of residual inorganic matter. The ashed product was transferred to a tube furnace, and high-purity H2 (flow rate 200 mL / min) was introduced. The temperature was increased to 400°C at a rate of 5°C / min and reduced under H2 atmosphere for 0.8 h. After reduction, the mixture was naturally cooled to room temperature under H2 atmosphere protection to obtain a copper-nickel mixture.

[0040] The preparation method of the composite adsorbent includes the following steps: (1) Weigh 100g of coconut shell activated carbon, add it to 500 mL of 15wt% nitric acid solution, and stir magnetically at 70℃ for 3h to fully oxidize the surface of the activated carbon. After the reaction is completed, filter it and wash it repeatedly with deionized water until the filtrate is neutral. Dry it in an oven at 80℃ for 12h and then add it to 4000 mL of Tris-HCl aqueous solution with pH 9. Mix it and stir ultrasonically at room temperature for 20h. The reaction product is separated by centrifugation, washed and vacuum dried to obtain polydopamine modified activated carbon. (2) Weigh 100g of polydopamine-modified activated carbon and add it to 600mL of anhydrous ethanol. Disperse it by ultrasonication for 15min. Add 15g of eugenol and stir to dissolve. Then slowly add 0.5mL of glacial acetic acid as a catalyst. Pour N2 for protection and heat to 75℃ for reflux reaction for 5h. After cooling, filter and wash with anhydrous ethanol and deionized water 3 times each. Dry in an oven at 80℃ for 12h to obtain the composite adsorbent.

[0041] This comparative example is similar to Example 1, except that 2-aminoimidazole-4-carboxylic acid was not added during the preparation of the composite adsorbent.

[0042] Comparative Example 4 A method for recovering copper and nickel from Kaldor slag, similar to Example 1, except that the pH is 5 in step S3.

[0043] Comparative Example 5 A method for recovering copper and nickel from Kaldor slag, similar to Example 1, except that the pH is 2.5 in step S3.

[0044] The copper-nickel mixtures obtained in Examples 1-3 and Comparative Examples 1-4 were weighed and their contents were tested. The test results are shown in Table 1. Table 1 Test Results

[0045] As can be seen from the experimental results in Table 1, the method of this application can efficiently recover copper and nickel from Kaldor slag.

[0046] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the patent protection scope of the present invention.

Claims

1. A method for recovering copper and nickel from Kaldor slag, characterized in that, Includes the following steps: S1. Kaldor slag pretreatment: After crushing the Kaldor slag, water is added and it is ground in a wet ball mill to make a slurry. Alkali solution is added to the slurry for alkali leaching, and the leaching solution and alkali leaching residue are obtained by filtration. S2. Add the alkaline leaching residue to the acid solution for pressurized oxidative leaching, and filter to obtain the acid leaching solution and acid leaching residue; S3. Add an alkaline neutralizing agent to the acid leaching solution to adjust the pH of the system to 3.0-4.0, stir the reaction, filter, separate the filter cake and filtrate, wash the filter cake with water, and combine the washing liquid and filtrate to obtain a neutralized solution. S4: Add composite adsorbent and auxiliary agent to the neutralization solution, stir and react. After the reaction is completed, filter, wash and dry to obtain adsorbent adsorbed with copper and nickel. S5. The adsorbent containing copper and nickel is ashed and then calcined under a hydrogen atmosphere to obtain a copper-nickel mixture.

2. The method according to claim 1, characterized in that: In step S2, the acid solution is a sulfuric acid solution, the heating temperature is 140-180℃, the oxygen partial pressure is 0.4-1.0MPa, and the acid leaching time is 1-3h.

3. The method according to claim 1, characterized in that: The preparation method of the composite adsorbent in step S4 includes the following steps: (1) After acidification pretreatment of activated carbon with nitric acid, it was mixed with dopamine in Tris-HCl aqueous solution and ultrasonically stirred at room temperature to obtain polydopamine modified activated carbon. (2) Polydopamine-modified activated carbon, 2-aminoimidazolium-4-carboxylic acid, and catalyst 4-dimethylaminopyridine were added to N,N-dimethylformamide for ultrasonic dispersion. Under ice bath conditions, DMF solution of N,N'-dicyclohexylcarbodiimide was added dropwise, followed by heating and reaction. After the reaction was completed, the activated carbon was washed and dried to obtain imidazole-functionalized activated carbon. (3) Imidazole-functionalized activated carbon was dispersed in anhydrous ethanol, eugenol was added, and glacial acetic acid was added dropwise as a catalyst. The mixture was refluxed under N2 protection to obtain a composite adsorbent.

4. The method according to claim 3, characterized in that: In step (1), the acidification pretreatment specifically involves adding activated carbon to a nitric acid solution with a mass fraction of 10-20%, stirring at 60-80℃ for 2-4 hours, filtering, washing until neutral, and drying.

5. The method according to claim 3, characterized in that: In step (1), the mass ratio of activated carbon to dopamine is 1:(2-4).

6. The method according to claim 3, characterized in that: In step (2), the mass ratio of polydopamine-modified activated carbon to 2-aminoimidazole-4-carboxylic acid is 100:8-15; the heating reaction temperature is 50-80℃ and the reaction time is 4-12h.

7. The method according to claim 3, characterized in that: In step (3), the mass ratio of imidazole functionalized activated carbon to syringaldehyde is 100:10-20; the reflux reaction temperature is 70-80℃ and the reaction time is 4-6h.

8. The method according to claim 1, characterized in that: In step S4, the adjuvant is sodium lauroyl methyl aminopropionate, and its addition amount is 2-5% of the mass of the composite adsorbent.

9. The method according to claim 1, characterized in that: In step S5, the ashing temperature is 600-800℃ and the time is 1-2 hours.

10. The method according to claim 1, characterized in that: In step S5, the calcination temperature is 380-420℃ and the time is 0.5-1h.

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