Method for realizing copper enrichment and recovery by adding auxiliary agent in copper-containing sludge non-flame combustion process

Abstract

The present application belongs to the field of sludge treatment, and provides a method for realizing copper enrichment and recovery by adding an additive in the non-flame combustion process of copper-containing sludge. Through the preparation of a multifunctional additive combined with staged heating and subsequent separation process, the enrichment and recovery of copper are realized. The additive A provides reducibility by using the nitrogen-containing carbon material generated by chitosan pyrolysis, and the iron oxide catalyzes the reduction of copper compounds. The additive B controls the redox reaction through the CeO2 oxygen vacancy, and the ZrO2 provides mechanical support. The additive C promotes the migration of copper compounds and removes impurity oxides by using a low-melting-point eutectic salt system. Staged heating sequentially completes the decomposition, migration and reduction of copper compounds, and finally forms a copper-rich slag. Subsequent strong magnetic separation removes iron impurities, and gravity separation enriches copper alloy. After acid leaching, a copper-containing leaching solution is generated, and copper ions are selectively extracted by using an extractant, finally realizing the recovery of high-purity copper.

Description

Technical Field

[0001] This invention belongs to the field of sludge treatment and relates to a method for copper enrichment and recovery by adding additives during the flameless combustion of copper-containing sludge. Background Technology

[0002] Copper-containing sludge is a common solid waste generated during industrial production processes, primarily originating from industries such as electroplating, electronic waste recycling, metallurgy, mining wastewater treatment, and chemical manufacturing. Copper-containing sludge is typically rich in metallic copper and its compounds, while also containing organic matter, metal oxides, and silicates. Its composition is complex, with common copper forms including metallic copper, copper oxide, copper sulfide, and copper chloride. It may also contain other valuable metals (such as nickel, zinc, and cobalt) and harmful impurities (such as lead, arsenic, and cadmium). Because chemical precipitation or adsorption processes are commonly used in wastewater treatment, this copper often exists in chemically bound or adsorbed forms within the sludge, further increasing the difficulty of treatment. With the rapid advancement of global industrialization and urbanization, the production of copper-containing sludge is increasing year by year. According to relevant statistics, the total amount of copper-containing sludge produced globally each year has reached millions of tons. Improper treatment of this sludge not only wastes its metal resources but can also cause serious environmental pollution. For example, unrecovered heavy metals in the sludge may enter soil and water bodies through leaching, thereby harming ecosystems and human health. Therefore, how to treat and recycle valuable metal resources in copper-containing sludge has become an important direction for current research on resource utilization technologies.

[0003] Currently, the main methods for treating copper-containing sludge include physical sorting, hydrometallurgy, and pyrolysis incineration. Physical sorting methods use flotation, magnetic separation, and gravity separation to initially enrich the metal components in the sludge, but the recovery efficiency is low for copper with small particle sizes and complex binding states. Hydrometallurgical technology has low separation efficiency for inert components in the sludge, resulting in a large amount of waste residue. Pyrolysis incineration technology has low copper enrichment efficiency during the process, and copper often remains in the slag in the form of oxides or silicates, making further recovery difficult. Flameless combustion technology has received increasing attention in waste treatment and energy utilization in recent years. This is a new type of heat treatment process based on a micro-reducing or slightly oxygen-enriched atmosphere to control the combustion process. Compared with traditional combustion technology, flameless combustion technology has the advantages of more uniform heat release and higher thermal efficiency by controlling the atmosphere and introducing multiphase catalysts. It can also promote the separation and enrichment of metal components by introducing molten salt, organic modifiers, or oxide catalysts to form a multiphase reaction system of molten salt-solid-gas phase. Resource utilization of copper-containing sludge is an important part of achieving a circular economy and green development. Developing a treatment method based on flameless combustion technology combined with additives can not only significantly improve the copper recovery rate, but also effectively reduce treatment costs and environmental pollution. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method for enriching and recovering copper by adding additives during the flameless combustion of copper-containing sludge. The method involves preparing additives A, B, and C, mixing the copper-containing sludge with the additives, pressing the mixture into tablets, and sequentially removing volatile components, decomposing and reducing copper compounds, and separating impurity oxides during a staged heating process. This results in a copper-rich slag. Iron-based alloys are removed by strong magnetic separation, and copper alloys are separated by gravity separation equipment. Acid leaching and extraction technologies are used to further convert copper into a copper-containing ion solution, and copper is selectively recovered using an extractant, thereby meeting the needs of actual production.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a method for copper enrichment and recovery by adding an additive during the flameless combustion of copper-containing sludge, the method comprising:

[0007] S1, disperse chitosan and ferric nitrate nonahydrate in deionized water, adjust the pH to 8, add sodium tripolyphosphate and graphene oxide, and heat and keep warm to obtain additive A;

[0008] S2, terephthalic acid is dispersed in the first part of DMF, and zirconium chloride and cerium nitrate hexahydrate are dispersed in the second part of DMF and then mixed with the terephthalic acid dispersion to obtain auxiliary agent B.

[0009] S3, mix halide salt, potassium tetraborate and sodium fluoride, heat and keep warm and then cool, add ionic liquid, molybdenum carbide and iron boride and mix to obtain auxiliary agent C;

[0010] S4, the dried and pulverized copper-containing sludge is mixed with additives A, B, and C in sequence with PVA solution to obtain a mixture. The mixture is then introduced with mixed gas and heated in stages to obtain slag product.

[0011] S5 involves crushing the slag product and using a strong magnetic separator to separate the iron-based alloy. The copper alloy is then separated by a gravity separation device. The copper alloy is immersed in acid to obtain a copper-containing leachate, which is then extracted using an extractant to recover the copper.

[0012] The method specifically includes:

[0013] S1. Chitosan and ferric nitrate nonahydrate are dispersed in deionized water, heated and stirred to dissolve, and the pH is adjusted to 8. Then, sodium tripolyphosphate and graphene oxide dispersion are added, mixed evenly, dried and ground, and the temperature is adjusted to the first temperature and kept warm under a nitrogen atmosphere to obtain additive A.

[0014] S2, terephthalic acid is dispersed in the first part of DMF, and zirconium chloride and cerium nitrate hexahydrate are dispersed in the second part of DMF and then mixed with the terephthalic acid dispersion. After mixing evenly, it is transferred to a high-pressure reactor lined with polytetrafluoroethylene, and the temperature is adjusted to the second temperature for reaction. After the reaction is completed, it is centrifuged, washed and placed under a nitrogen atmosphere. The temperature is adjusted to the third temperature for heat preservation to obtain additive B.

[0015] S3, after mixing halide salt, potassium tetraborate and sodium fluoride, adjust the temperature to the fourth temperature under nitrogen atmosphere and keep it at that temperature, then quickly pour it into a metal mold to cool, grind it after cooling, add ionic liquid, molybdenum carbide and iron boride, mix and dry to obtain auxiliary agent C;

[0016] S4, the dried and pulverized copper-containing sludge is mixed with additives A, B, and C in sequence with PVA solution. The mixture is pressed into tablets and dried to obtain a mixed material. The mixed material is passed through a mixed gas and heated in stages. After the heating is completed, nitrogen is continuously passed through and the product is naturally cooled to obtain slag.

[0017] S5 involves crushing the slag product and using a strong magnetic separator to separate the iron-based alloy. The copper alloy is then separated by a gravity separation device. The copper alloy is immersed in acid to obtain a copper-containing leachate, which is then extracted using an extractant to recover the copper.

[0018] Chitosan is a natural polysaccharide with abundant hydroxyl and amino groups in its molecular structure. These multifunctional groups not only endow chitosan with high chemical reactivity but also with excellent coordination ability with metal ions. In particular, the amino groups, with their lone pairs of electrons, can form stable coordination bonds with transition metal ions, resulting in strong complexation. When ferric nitrate nonahydrate is dispersed in water, its molecular structure dissociates, releasing ferric ions and nitrate ions. Ferric ions, as typical Lewis acids, readily coordinate with the amino and hydroxyl groups in chitosan molecules, forming chitosan-iron complexes. This complexation significantly improves the material's metal ion carrying capacity and endows it with metal active centers. In this process, the complexation of chitosan's amino groups with ferric ions effectively stabilizes iron ions by forming stable complexes, preventing unnecessary precipitation or dispersion in solution. The formed chitosan-iron complex not only possesses excellent chemical stability but can also be transformed into functional iron oxides during subsequent heat treatment, thereby endowing the material with magnetic and catalytic activity. These functional properties play a crucial role in the subsequent treatment of copper-containing sludge: First, the active sites on the surface of iron oxides can chemically adsorb or complex with copper ions or copper compounds, thereby significantly improving the enrichment efficiency of copper. Second, the magnetic properties of iron oxides provide a physical basis for the subsequent effective separation of copper from other impurities through magnetic separation. Under alkaline conditions, the amino groups of chitosan gradually deprotonate, enhancing its electron-donating ability and thus improving its complexation efficiency with ferric ions. Simultaneously, some ferric ions undergo hydrolysis under alkaline conditions to generate Fe(OH)3 precipitate. Fe(OH)3 is an important precursor for the formation of iron oxides. During subsequent high-temperature heat treatment, Fe(OH)3 decomposes and transforms into functional iron oxides. The formation of these iron oxides not only improves the thermal stability of the material but also endows it with excellent catalytic performance and adsorption capacity, enabling it to significantly promote the reduction reaction and enrichment process of copper under high-temperature conditions.

[0019] Meanwhile, the introduction of sodium tripolyphosphate further enhances the functionality of the system. Sodium tripolyphosphate is a typical multidentate ligand that can complex with ferric ions to form ferric phosphates or other phosphorus-containing compounds. These compounds have extremely high thermal stability and redox activity, and can further decompose and react with iron compounds during subsequent heat treatment to form more complex ferric phosphate structures. The formation of ferric phosphates not only significantly improves the adsorption capacity of the material but also provides additional redox active sites, enabling it to effectively promote the reduction reaction of copper compounds in high-temperature environments. The presence of phosphate ions can also reduce the reduction activation energy of copper oxides by changing the local reaction environment, thereby achieving efficient conversion of copper from the oxidized state to the metallic state. In addition, the high chemical stability of ferric phosphates enables them to effectively capture copper ions or copper oxides, further improving the enrichment efficiency of copper. The introduction of graphene oxide provides another important pathway for improving the performance of the material. Graphene oxide is a carbon material with a two-dimensional layered structure, and its surface is rich in oxygen-containing functional groups such as hydroxyl and carboxyl groups. These functional groups can interact weakly with iron ions or other metal ions, enhancing the dispersibility and uniformity of the material. During subsequent high-temperature heat treatment, graphene oxide is partially reduced to reduced graphene oxide, exhibiting high conductivity and chemical stability, while simultaneously forming a porous network structure. The high conductivity of reduced graphene oxide acts as an electron donor during the reduction of copper, accelerating the transformation from the oxidized state to the metallic state. At the same time, its porous structure provides more active sites for the adsorption and dispersion of copper ions or copper oxides, further enhancing the material's enrichment capacity. Furthermore, the network structure of reduced graphene oxide also enhances the mechanical strength and thermal stability of the composite material, ensuring its long-term use under high-temperature conditions.

[0020] During high-temperature heat treatment, chitosan decomposes and releases small molecules, while simultaneously carbonizing into a porous nitrogen-containing carbon material. The residual nitrogen functional groups on the surface of this nitrogen-containing carbon material further enhance its adsorption capacity for metal ions and its surface reactivity. Meanwhile, Fe(OH)3 or chitosan-iron complexes generate magnetic iron oxides during pyrolysis, enhancing the material's magnetic separation function. Furthermore, reduced graphene oxide and carbonized chitosan together form a highly conductive and porous composite matrix. This composite matrix not only significantly improves the material's adsorption and catalytic performance but also further enhances copper enrichment efficiency through its high specific surface area and dispersibility. Through the complexing effect of chitosan, the reactivity of sodium tripolyphosphate, the conductivity and porous network structure of graphene oxide, and the synergistic effect of multiple functional materials during high-temperature heat treatment, additive A prepared by S1 is a multifunctional composite material. This material possesses multiple functions, including efficient adsorption of copper ions, catalytic reduction of copper, and copper enrichment through magnetism and a porous structure, providing crucial support for the subsequent treatment of copper-containing sludge and copper recovery.

[0021] Terephthalic acid is a typical organic dicarboxylic acid molecule containing two highly reactive carboxyl groups in its molecular structure. These carboxyl groups can be deprotonated under solvothermal conditions to form a carboxylate ion. The carboxylate ion is an excellent ligand with strong electron-donating ability, capable of stably forming coordinate bonds with empty orbitals of metal ions. This coordination allows terephthalic acid to combine with various metal ions to form highly ordered metal-organic frameworks. In this invention, zirconium chloride is used as the metal node material of the metal-organic framework, its main function being to provide Zr... 4+ Ions serve as structural centers in Zr. 4+ Zirconium is a high-valence metal ion with a high coordination number and strong Lewis acidity, enabling it to coordinate with the carboxylate groups of multiple terephthalic acid molecules to form a zirconium-based MOF structure. This coordination not only endows the MOF with a three-dimensional porous network structure but also significantly improves the material's thermal and chemical stability, allowing it to maintain structural integrity under high-temperature conditions. Furthermore, Zr... 4+ The Lewis acidity of the material provides numerous surface-active sites, which can interact with copper ions or copper compounds during the treatment of copper-containing sludge, thereby selectively adsorbing and enriching copper. Cerium nitrate is another key metal source, providing Ce. 3+ Ions and Zr 4+ Jointly participate in the construction of MOF. Ce 3+ Its unique feature lies in its reversible redox behavior. This property makes Ce 3+ In MOFs, Ce not only serves as a structural node but also introduces redox active centers. In solvothermal reactions, Ce... 3+ It undergoes a coordination reaction with terephthalic acid to form cerium-based MOFs. 3+ The redox properties of Ce endow the material with excellent catalytic ability, which is further activated during subsequent high-temperature heat treatment, manifesting as Ce 3+ It is converted into CeO2 (cerium oxide). Cerium oxide is an inorganic material with unique redox properties, and its surface can generate a large number of oxygen vacancies. Oxygen vacancies are regions on the CeO2 surface lacking oxygen atoms. These sites have good chemical activity and can promote redox reactions by capturing oxygen atoms in oxides. In the treatment of copper-containing sludge, oxygen vacancies can effectively react with copper oxides, promoting the reduction of copper oxides and converting them into metallic copper. This oxygen vacancy effect significantly improves the copper recovery efficiency, making CeO2 an indispensable key component in the entire additive system. Under solvothermal reaction conditions, the final product is a MOF (Metal-Oxide-Foil) constructed from zirconium and cerium, which has a highly ordered porous structure and a high specific surface area.

[0022] The prepared MOF material underwent a high-temperature heat treatment process at 300-310℃ under a nitrogen atmosphere. During this process, the organic ligands (terephthalic acid) of the MOF decomposed, generating CO2 and a small amount of carbon residue. Simultaneously, the metal nodes of the MOF underwent an inorganic transformation, and Zr... 4+ and Ce 3+ The cerium oxide and zirconium oxide are converted respectively. Zirconia is a highly stable inorganic material that maintains chemical inertness and physical stability at high temperatures while providing mechanical support to maintain the porous structure of the material. This property of ZrO2 ensures the long service life of the material under high-temperature conditions and provides a stable physical platform for the adsorption of copper compounds, further enhancing the enrichment capacity of the additives. Cerium oxide exhibits unique redox behavior during high-temperature treatment. 3+ and Ce 4+ Through electron exchange, a large number of oxygen vacancies are generated on the surface of CeO2. These oxygen vacancies not only enhance the surface activity of CeO2 but also improve its catalytic ability in high-temperature environments. By capturing oxygen atoms in oxides, oxygen vacancies can effectively promote the reduction reaction of copper oxides, converting CuO or Cu2O into metallic copper. This process not only accelerates the reduction kinetics of copper but also lowers the activation energy of copper oxide reduction to some extent. The resulting additive B is a composite material with ZrO2 and CeO2 as the main components, combining the high stability of ZrO2 and the redox activity of CeO2, providing functional support for the selective adsorption and efficient reduction of copper. The stable structure of ZrO2 ensures the long-term use of the additive in high-temperature environments, while the oxygen vacancies of CeO2 provide chemically active sites for the enrichment and reduction of copper. This synergistic effect enables additive B to exhibit excellent performance in the copper recovery process, providing an important technological foundation for achieving efficient and green copper resource recovery.

[0023] Halide salts melt at high temperatures, forming a low-melting-point eutectic salt system. This eutectic system is attributed to the synergistic effect between different halides, significantly weakening the lattice energy of individual halides and thus lowering the overall melting point. Through this mechanism, the melting point of the molten salt system is typically lower than that of the pure component salts, significantly reducing the energy consumption required for the reaction. In this invention, the formation of the molten salt system not only provides a uniform liquid environment for the reaction but also enhances the solubility and migration ability of the reactants through its ionization. Ionization is one of the core functions of the molten salt system. Through ionization, the cations and anions in the halide salt can dissolve copper oxides and other metal oxides, reducing the surface energy of these oxides. This reduction in surface energy makes the crystal structure of copper oxides easier to break down, thereby promoting its chemical contact with other components. This co-solubilizing effect plays a crucial role in the reduction of copper oxides to metallic copper, while significantly inhibiting the possibility of other impurity oxides participating in the reaction. In the molten salt system, copper, due to its low electrochemical activity, reacts with Li... + K + Na + Compared to highly reactive metal ions, it is more likely to undergo reduction reactions preferentially. Furthermore, Cl in molten salt... - Copper ions can form stable complexes with copper ions. The formation of these complexes further reduces the chemical potential of copper ions, thereby increasing their mobility and reactivity. Through the stabilizing effect of the complexes, the dispersion and mass transfer efficiency of copper ions in the molten salt system are enhanced. This phenomenon not only accelerates the reduction reaction rate of copper oxides but also further promotes the enrichment effect of copper, enabling its effective separation from impurities.

[0024] Potassium tetraborate decomposes at high temperatures to form boron oxide (B₂O₃). B₂O₃ is a strong acidic oxide with significant fluxing properties. The introduction of B₂O₃ further reduces the viscosity and melting point of the molten salt system, while improving its fluidity and homogeneity. This fluidity optimizes the contact efficiency of the reactants, allowing copper compounds to react rapidly and fully with other components in the molten salt. Furthermore, B₂O₃ has high chemical affinity, enabling stable interactions with copper compounds through chemisorption or complexation, further enhancing the selective separation of copper. This adsorption not only stabilizes the copper compounds but also inhibits the deposition of other impurities in the system, thereby improving the separation efficiency and enrichment effect of copper. The presence of boron oxide also plays an important role in regulating the local redox environment; by reacting with oxides in the system, boron oxide can accelerate the reduction process of copper oxides.

[0025] The introduction of sodium fluoride further optimizes the chemical environment of the molten salt system. As a highly electronegative halide, sodium fluoride's fluoride ions exhibit high chemical reactivity. In the high-temperature molten system, fluoride ions can react with copper compounds or other metal oxides to generate volatile or low-melting-point fluorides. These fluorides either escape in the gaseous state or dissolve in the molten salt, thus achieving efficient separation of impurity oxides, reducing the interference of impurities on the copper enrichment process, and enabling copper to be enriched and recovered with higher purity. The role of sodium fluoride is also reflected in its complexation with copper ions. Fluoride ions can form stable complexes with copper ions, which further enhance the mobility and reactivity of copper by lowering the chemical potential of copper ions. In the molten salt system, the synergistic effect of fluoride ions and chloride ions significantly accelerates the reduction reaction of copper oxides and enhances the selective enrichment effect of copper. The introduction of sodium fluoride not only improves the copper recovery efficiency but also further optimizes the overall chemical properties of the molten salt system. Under high-temperature conditions, halide salts, potassium tetraborate, and sodium fluoride synergistically form a low-viscosity, highly reactive molten system. This system provides an ideal reaction medium for the mass transfer, migration, and enrichment of copper. The halide salts reduce the surface energy of copper oxides through ionization, promoting the reduction process. Potassium tetraborate further optimizes the system's fluidity by generating boron oxides and enhances the separation selectivity of copper through adsorption and redox regulation. Sodium fluoride improves the enrichment efficiency of copper and reduces impurity interference through selective reactions with impurities and copper compounds.

[0026] The main components of copper-containing sludge are copper compounds and other impurity oxides. Copper compounds are the target for enrichment, while impurity oxides easily eutectic or mix with copper compounds, affecting the selective recovery of copper. Additive A is a chitosan-iron composite material that combines the porous adsorption properties of chitosan, the magnetic properties of iron oxides, and the reducing properties of nitrogen-containing carbon materials generated by high-temperature pyrolysis. During heat treatment, the iron oxides in Additive A can catalyze the selective reduction of copper, while simultaneously achieving magnetic separation in the subsequent slag treatment stage. Additive B is a composite material that, through high-temperature treatment, possesses oxygen vacancies and a stable porous structure. The oxygen vacancies on the CeO2 surface can participate in the redox cycle. ZrO2 captures oxygen atoms in oxides, promoting the reduction of copper oxides. At high temperatures, ZrO2 provides mechanical support, maintaining the material's physical structure and ensuring uniform distribution of the additives during enrichment. Additive C is a composite system based on halide salts, potassium tetraborate, and sodium fluoride. It melts at high temperatures to form a low-melting-point eutectic salt system, providing a liquid medium for the migration, diffusion, and reaction of copper compounds, thus lowering the reaction activation energy. Potassium tetraborate reduces the viscosity of the molten salt system, improving the contact efficiency between copper compounds and other components. Simultaneously, it stabilizes copper compounds through adsorption, enhancing separation selectivity. Sodium fluoride reacts with impurity oxides to generate volatile or low-melting-point fluorides, effectively removing impurities.

[0027] In the first stage of heating, below 300℃, the physically adsorbed water and some chemically bound water remaining in the copper-containing sludge begin to gradually disappear. During this process, the water evaporates into a gaseous state, which helps reduce the humidity of the system and avoids interference from water vapor at subsequent high temperatures on copper oxides. Simultaneously, low-molecular-weight organic matter that may be present in the copper-containing sludge undergoes thermal decomposition or oxidative decomposition at this stage, generating volatile small molecules. Polyvinyl alcohol, acting as a binder, decomposes during heating, generating carbonaceous residues. These carbonaceous residues are important electron donors for the subsequent reduction of copper oxides, providing a reducing atmosphere for the reduction of copper oxides under high-temperature conditions. Chitosan in additive A decomposes at this stage, releasing small-molecule gases and carbonizing into porous nitrogen-containing carbon material. The surface of the nitrogen-containing carbon material is rich in active sites, which can selectively adsorb copper compounds, providing a reaction platform for the subsequent reduction reaction. Simultaneously, an excess air coefficient of 1.2 indicates a slight excess of oxygen in the atmosphere at this stage, providing a mild oxidizing environment. This environment is conducive to the complete decomposition of organic impurities and can oxidize some sulfides, reducing the interference of sulfides on subsequent reactions. In the second stage of heating, some copper compounds begin to decompose, forming copper oxide or copper suboxide. During this stage, CeO2 in additive B begins to generate oxygen vacancies, exhibiting redox activity. Oxygen vacancies are sites in CeO2 crystals lacking oxygen atoms and possess high chemical activity, capable of capturing oxygen atoms in the system. Through the generation of oxygen vacancies, CeO2 enhances its redox regulation of copper oxides and provides active adsorption sites for copper compounds. In this stage, the halide salt in additive C gradually melts, forming a low-melting-point, highly fluid eutectic salt system. The molten salt enhances the solubility and migration of copper compounds through ionization, while also providing a liquid medium for copper enrichment. An excess air coefficient of 1.0 indicates that a neutral redox environment is maintained during this stage. This atmosphere facilitates the decomposition of copper compounds while preventing excessive oxidation, ensuring that CuO or Cu2O remains the predominant form. In the three-stage heating process, copper oxides begin to react with carbonaceous residues, initially reducing them to metallic copper. The reaction rate accelerates with increasing temperature, regulated by a redox atmosphere. At this stage, the nitrogen-containing carbon material in additive A, rich in electron donors, further promotes the reduction kinetics of copper. The halide salts in additive C completely melt at this stage, forming a highly fluid liquid system, providing an ideal medium for the migration and diffusion of copper compounds. Sodium fluoride reacts with impurity oxides to generate volatile or low-melting-point fluorides, gradually removing impurities from the system. Oxygen vacancies in CeO2 are further enhanced at this stage, interacting with the surfaces of CuO or Cu2O, accelerating the redox process and ensuring a high-efficiency conversion of copper compounds to metallic copper. An excess air coefficient of 0.9 indicates a slightly reducing redox environment at this stage, ensuring partial reduction of copper oxides while avoiding side reactions under completely oxygen-deficient conditions.The four-stage heating process, within the range of 700-900℃, reduces copper oxides to metallic copper. The carbonaceous residues produced by the decomposition of additives A and PVA, the oxygen vacancies in CeO2 from additive B, and the ions in additive C work together to provide a strong reducing environment, accelerating the reduction reaction of copper. Due to its higher density, metallic copper gradually settles to the bottom of the melt in the molten salt system, forming a copper-rich metal layer. Impurity oxides react completely with the molten salt in this stage, forming a stable slag network structure. Boron oxides further improve the separation efficiency of impurities by regulating the viscosity of the molten salt. An excess air coefficient of 0.8 provides a significant reducing atmosphere, preventing secondary oxidation of copper while ensuring complete stabilization of impurity oxides.

[0028] As a preferred technical solution of the present invention, in step S1, the mass ratio of chitosan, ferric nitrate nonahydrate, sodium tripolyphosphate and graphene oxide is 80:15:7:2.

[0029] In some optional embodiments, the mass-to-volume ratio of chitosan to deionized water is 4 g: 25 mL.

[0030] In some alternative embodiments, the first temperature is 400-450°C, for example, it can be 400°C, 405°C, 410°C, 415°C, 420°C, 425°C, 430°C, 435°C, 440°C, 445°C or 450°C, but is not limited to the listed temperatures, other unlisted temperatures within this temperature range are also applicable.

[0031] In some optional embodiments, the holding time at the first temperature is 2-3 hours, for example, it can be 2.0 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3.0 hours, but it is not limited to the listed times. Other unlisted times within this time range are also applicable.

[0032] As a preferred embodiment of the present invention, in step S2, the mass ratio of terephthalic acid, zirconium chloride and cerium nitrate hexahydrate is 10:14:1.5.

[0033] In some optional embodiments, the mass-to-volume ratio of the terephthalic acid to the first DMF is 1 g: 10 mL.

[0034] In some optional embodiments, the zirconium chloride to the second part of DMF has a mass-to-volume ratio of 1 g: 10 mL.

[0035] In some alternative embodiments, the second temperature is 130-140°C, for example, it can be 130°C, 131°C, 132°C, 133°C, 134°C, 135°C, 136°C, 137°C, 138°C, 139°C or 140°C, but is not limited to the listed temperatures, other unlisted temperatures within this temperature range are also applicable.

[0036] In some alternative embodiments, the second temperature reaction time is 20-22 hours, for example, 20 hours, 20.2 hours, 20.4 hours, 20.6 hours, 20.8 hours, 21.0 hours, 21.2 hours, 21.4 hours, 21.6 hours, 21.8 hours, or 22.0 hours, but is not limited to the listed times; other unlisted times within this time range are also applicable.

[0037] In some alternative embodiments, the third temperature is 300-310°C, for example, it can be 300°C, 301°C, 302°C, 303°C, 304°C, 305°C, 306°C, 307°C, 308°C, 309°C or 310°C, but is not limited to the listed temperatures, other unlisted temperatures in this temperature range are also applicable.

[0038] In some optional embodiments, the time for maintaining the third temperature is 1-2 hours, for example, it can be 1.0h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2.0h, but it is not limited to the listed times. Other unlisted times within this time range are also applicable.

[0039] As a preferred technical solution of the present invention, in step S3, the mass ratio of the halide salt, potassium tetraborate, sodium fluoride, ionic liquid, molybdenum carbide and iron boride is 24:5:3:4:(1-2):(1-2).

[0040] In some optional embodiments, the halide salt is LiCl, KCl and NaCl in a mass ratio of 1:1:1.

[0041] In some alternative embodiments, the fourth temperature is 500-600°C, for example, it can be 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C or 600°C, but is not limited to the listed temperatures, other unlisted temperatures in this temperature range are also applicable.

[0042] In some optional embodiments, the holding time for the fourth temperature is 50-60 minutes, for example, it can be 50 minutes, 51 minutes, 52 minutes, 53 minutes, 54 minutes, 55 minutes, 56 minutes, 57 minutes, 58 minutes, 59 minutes or 60 minutes, but it is not limited to the listed time. Other unlisted times within this time range are also applicable.

[0043] As a preferred technical solution of the present invention, in step S4, the mass ratio of the dried and pulverized copper-containing sludge, additive A, additive B and additive C is 1000:(7-10):(5-7):(4-6).

[0044] In some optional embodiments, the mass-to-volume ratio of the dried and pulverized copper-containing sludge to the PVA solution is 100 g: (3-5) mL, and the mass fraction of the PVA solution is 1 wt.%.

[0045] In some alternative embodiments, the mixed gas is nitrogen and air, with the nitrogen flow rate at 0.7 L / min and the air flow rate at 0.1 L / min.

[0046] In some optional embodiments, the staged heating is: a single stage, heating to 300°C at a heating rate of 10°C / min, holding for 40min, and an excess air coefficient of 1.2.

[0047] The second stage involves heating from 300℃ to 500℃ at a rate of 10℃ / min, holding for 30 minutes, and using an excess air coefficient of 1.0.

[0048] The process involves three stages: heating from 500℃ to 700℃ at a rate of 5℃ / min, holding for 50 minutes, and using an excess air coefficient of 0.9.

[0049] The process involves four stages: heating from 700℃ to 900℃ at a rate of 5℃ / min, holding for 60 minutes, and using an excess air coefficient of 0.8.

[0050] As a preferred technical solution of the present invention, in step S5, the acid solution is a 5 wt.% hydrochloric acid solution.

[0051] In some optional embodiments, the extractant is LIX984.

[0052] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) By preparing additives A, B, and C and achieving synergistic effects in the staged heating process, the reduction, migration, and enrichment process of copper compounds is significantly optimized. The nitrogen-containing carbon materials and iron oxides in additive A provide strong reducing and catalytic activity. Additive B regulates the redox reaction through the oxygen vacancy of CeO2. Additive C improves the migration efficiency of copper compounds through the low-melting-point eutectic salt system and effectively removes impurity oxides. (2) By designing additives and optimizing heat treatment conditions, this method reduces the large amount of energy consumption and the use of strong oxidants required for high-temperature smelting or chemical reduction in traditional metallurgical processes. The use of fluoride and halide salts in additive C forms a low-melting-point eutectic system, which avoids the complexity of high-temperature slag treatment, reduces the difficulty of impurity oxide treatment, and reduces environmental pollution. Attached Figure Description

[0053] Figure 1 The present invention provides a flowchart of a method for enriching and recovering copper by adding an additive during the flameless combustion of copper-containing sludge in embodiments 1-4 of the present invention. Detailed Implementation

[0054] The technical solutions of the present invention will be described in detail below with reference to specific embodiments and accompanying drawings. The embodiments described herein are specific implementations of the present invention, used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary, and should not be construed as limiting the implementation methods or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can employ other obvious technical solutions based on the content disclosed in the claims and specification of this application. These technical solutions include those that make any obvious substitutions and modifications to the embodiments described herein.

[0055] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone any further purification treatment.

[0056] Example 1

[0057] This embodiment provides a method for copper enrichment and recovery by adding an additive during the flameless combustion of copper-containing sludge. The method specifically includes the following steps:

[0058] S1. Disperse 800g chitosan and 150g ferric nitrate nonahydrate in 5L deionized water, heat and stir to dissolve, adjust pH to 8, then add 70g sodium tripolyphosphate and 20g graphene oxide, mix evenly, dry and grind, and keep warm at 410℃ for 2.2h under nitrogen atmosphere to obtain additive A.

[0059] S2, 10g of terephthalic acid was dispersed in 100ml of LDMF, and then 14g of zirconium chloride and 1.5g of cerium nitrate hexahydrate were dispersed in 100ml of LDMF and mixed with the terephthalic acid dispersion. After mixing evenly, the mixture was transferred to a high-pressure reactor lined with polytetrafluoroethylene. The temperature was adjusted to 130℃ and the reaction was carried out for 21.2h. After the reaction was completed, the mixture was centrifuged, washed, and placed under a nitrogen atmosphere. The temperature was adjusted to 306℃ and kept at that temperature for 1.8h to obtain additive B.

[0060] S3, after mixing 240g of halide salt, 50g of potassium tetraborate and 30g of sodium fluoride, the temperature was adjusted to 550℃ and kept for 51min under nitrogen atmosphere, and then quickly poured into a metal mold to cool. After cooling, it was ground and mixed with 40g of ionic liquid, 13g of molybdenum carbide and 19g of iron boride. After drying, the additive C was obtained.

[0061] S4. 10 kg of dried and pulverized copper-containing sludge was sequentially mixed with 77 g of additive A, 51 g of additive B, 44 g of additive C, and 30 mL of 1 wt.% PVA solution. The mixture was then compressed into tablets and dried to obtain a final mixture. This final mixture was then passed through a mixed gas and heated in stages. In the first stage, the temperature was raised to 300℃ at a rate of 10℃ / min and held for 40 min, with an excess air coefficient of 1.2. In the second stage, the temperature was raised from 300℃ to 500℃... The heating rate was 10℃ / min, the holding time was 30min, and the excess air coefficient was 1.0. The process was divided into three stages: heating from 500℃ to 700℃ at a heating rate of 5℃ / min and a holding time of 50min, with an excess air coefficient of 0.9; and heating from 700℃ to 900℃ at a heating rate of 5℃ / min and a holding time of 60min, with an excess air coefficient of 0.8. After heating, nitrogen was continuously introduced, and the product was naturally cooled to obtain slag.

[0062] S5. After crushing the slag product, the iron-based alloy is separated by a strong magnetic separator, and the copper alloy is separated by a gravity separation device. The copper alloy is then treated with a 5wt.% hydrochloric acid solution to obtain a copper-containing leachate, and copper is recovered using LIX984.

[0063] Example 2

[0064] This embodiment provides a method for copper enrichment and recovery by adding an additive during the flameless combustion of copper-containing sludge. The method specifically includes the following steps:

[0065] S1. Disperse 800g chitosan and 150g ferric nitrate nonahydrate in 5L deionized water, heat and stir to dissolve, adjust pH to 8, then add 70g sodium tripolyphosphate and 20g graphene oxide, mix evenly, dry and grind, and keep warm at 450℃ for 2.9h under nitrogen atmosphere to obtain additive A.

[0066] S2, 10g of terephthalic acid was dispersed in 100ml of LDMF, and then 14g of zirconium chloride and 1.5g of cerium nitrate hexahydrate were dispersed in 100ml of LDMF and mixed with the terephthalic acid dispersion. After mixing evenly, the mixture was transferred to a high-pressure reactor lined with polytetrafluoroethylene. The temperature was adjusted to 139℃ and the reaction was carried out for 20.3h. After the reaction was completed, the mixture was centrifuged, washed, and placed under a nitrogen atmosphere. The temperature was adjusted to 301℃ and kept at that temperature for 1.4h to obtain additive B.

[0067] S3, mix 240g of halide salt, 50g of potassium tetraborate and 30g of sodium fluoride, adjust the temperature to 510℃ and keep it at that temperature for 58min under a nitrogen atmosphere, then quickly pour it into a metal mold to cool, grind it after cooling and add 40g of ionic liquid, 18g of molybdenum carbide and 16g of iron boride, mix it and dry it to obtain auxiliary agent C.

[0068] S4. 10 kg of dried and pulverized copper-containing sludge was sequentially mixed with 95 g of additive A, 59 g of additive B, 58 g of additive C, and 38 mL of 1 wt.% PVA solution. The mixture was then compressed into tablets and dried to obtain a final mixture. This mixture was then passed through a mixed gas and heated in stages. In the first stage, the temperature was raised to 300℃ at a rate of 10℃ / min and held for 40 min, with an excess air coefficient of 1.2. In the second stage, the temperature was raised from 300℃ to 500℃... The heating rate was 10℃ / min, the holding time was 30min, and the excess air coefficient was 1.0. The process was divided into three stages: heating from 500℃ to 700℃ at a heating rate of 5℃ / min and a holding time of 50min, with an excess air coefficient of 0.9; and heating from 700℃ to 900℃ at a heating rate of 5℃ / min and a holding time of 60min, with an excess air coefficient of 0.8. After heating, nitrogen was continuously introduced, and the product was naturally cooled to obtain slag.

[0069] S5. After crushing the slag product, the iron-based alloy is separated by a strong magnetic separator, and the copper alloy is separated by a gravity separation device. The copper alloy is then treated with a 5wt.% hydrochloric acid solution to obtain a copper-containing leachate, and copper is recovered using LIX984.

[0070] Example 3

[0071] This embodiment provides a method for copper enrichment and recovery by adding an additive during the flameless combustion of copper-containing sludge. The method specifically includes the following steps:

[0072] S1. Disperse 800g chitosan and 150g ferric nitrate nonahydrate in 5L deionized water, heat and stir to dissolve, adjust pH to 8, then add 70g sodium tripolyphosphate and 20g graphene oxide, mix evenly, dry and grind, and keep warm at 420℃ for 2.4h under nitrogen atmosphere to obtain additive A.

[0073] S2, 10g of terephthalic acid was dispersed in 100ml of LDMF, and then 14g of zirconium chloride and 1.5g of cerium nitrate hexahydrate were dispersed in 100ml of LDMF and mixed with the terephthalic acid dispersion. After mixing evenly, the mixture was transferred to a high-pressure reactor lined with polytetrafluoroethylene. The temperature was adjusted to 137℃ and the reaction was carried out for 21.8h. After the reaction was completed, the mixture was centrifuged, washed, and placed under a nitrogen atmosphere. The temperature was adjusted to 309℃ and kept at that temperature for 1.1h to obtain additive B.

[0074] S3, after mixing 240g of halide salt, 50g of potassium tetraborate and 30g of sodium fluoride, the temperature was adjusted to 590℃ and kept for 53min under nitrogen atmosphere, and then quickly poured into a metal mold to cool. After cooling, it was ground and mixed with 40g of ionic liquid, 16g of molybdenum carbide and 14g of iron boride. After drying, the additive C was obtained.

[0075] S4, 10 kg of dried and pulverized copper-containing sludge was sequentially mixed with 83 g of additive A, 67 g of additive B, 47 g of additive C, and 47 mL of 1 wt.% PVA solution. The mixture was then compressed into tablets and dried to obtain a final mixture. This final mixture was then passed through a mixed gas and heated in stages. In the first stage, the temperature was raised to 300℃ at a rate of 10℃ / min and held for 40 min, with an excess air coefficient of 1.2. In the second stage, the temperature was raised from 300℃ to 500℃... The heating rate was 10℃ / min, the holding time was 30min, and the excess air coefficient was 1.0. The process was divided into three stages: heating from 500℃ to 700℃ at a heating rate of 5℃ / min and a holding time of 50min, with an excess air coefficient of 0.9; and heating from 700℃ to 900℃ at a heating rate of 5℃ / min and a holding time of 60min, with an excess air coefficient of 0.8. After heating, nitrogen was continuously introduced, and the product was naturally cooled to obtain slag.

[0076] S5. After crushing the slag product, the iron-based alloy is separated by a strong magnetic separator, and the copper alloy is separated by a gravity separation device. The copper alloy is then treated with a 5wt.% hydrochloric acid solution to obtain a copper-containing leachate, and copper is recovered using LIX984.

[0077] Example 4

[0078] This embodiment provides a method for copper enrichment and recovery by adding an additive during the flameless combustion of copper-containing sludge. The method specifically includes the following steps:

[0079] S1. Disperse 800g chitosan and 150g ferric nitrate nonahydrate in 5L deionized water, heat and stir to dissolve, adjust pH to 8, then add 70g sodium tripolyphosphate and 20g graphene oxide, mix evenly, dry and grind, and keep warm at 440℃ for 2.6h under nitrogen atmosphere to obtain additive A.

[0080] S2, 10g of terephthalic acid was dispersed in 100ml of LDMF, and then 14g of zirconium chloride and 1.5g of cerium nitrate hexahydrate were dispersed in 100ml of LDMF and mixed with the terephthalic acid dispersion. After mixing evenly, the mixture was transferred to a high-pressure reactor lined with polytetrafluoroethylene. The temperature was adjusted to 135℃ and the reaction was carried out for 20.7h. After the reaction was completed, the mixture was centrifuged, washed, and placed under a nitrogen atmosphere. The temperature was adjusted to 304℃ and kept at that temperature for 1.7h to obtain additive B.

[0081] S3, after mixing 240g of halide salt, 50g of potassium tetraborate and 30g of sodium fluoride, the temperature was adjusted to 530℃ and kept for 57min under nitrogen atmosphere, and then quickly poured into a metal mold to cool. After cooling, it was ground and mixed with 40g of ionic liquid, 14g of molybdenum carbide and 12g of iron boride. After drying, the additive C was obtained.

[0082] S4, 10 kg of dried and pulverized copper-containing sludge is sequentially mixed with 70 g of additive A, 62 g of additive B, 53 g of additive C, and 42 mL of 1 wt.% PVA solution. The mixture is then compressed into tablets and dried to obtain a final mixture. This final mixture is then passed through a mixed gas and heated in stages. In the first stage, the temperature is raised to 300℃ at a rate of 10℃ / min and held for 40 min, with an excess air coefficient of 1.2. In the second stage, the temperature is raised from 300℃ to 500℃... The heating rate was 10℃ / min, the holding time was 30min, and the excess air coefficient was 1.0. The process was divided into three stages: heating from 500℃ to 700℃ at a heating rate of 5℃ / min and a holding time of 50min, with an excess air coefficient of 0.9; and heating from 700℃ to 900℃ at a heating rate of 5℃ / min and a holding time of 60min, with an excess air coefficient of 0.8. After heating, nitrogen was continuously introduced, and the product was naturally cooled to obtain slag.

[0083] S5. After crushing the slag product, the iron-based alloy is separated by a strong magnetic separator, and the copper alloy is separated by a gravity separation device. The copper alloy is then treated with a 5wt.% hydrochloric acid solution to obtain a copper-containing leachate, and copper is recovered using LIX984.

[0084] Comparative Example 1

[0085] This comparative example provides a method for copper enrichment and recovery by adding an additive during the flameless combustion of copper-containing sludge. The difference between this method and Example 1 is that the mass of additive A in S4 is 120g, which is 50g more than in Example 1. Other process parameters and operating conditions are exactly the same as in Example 1.

[0086] Comparative Example 2

[0087] This comparative example provides a method for copper enrichment and recovery by adding an additive during the flameless combustion of copper-containing sludge. The difference between this method and Example 1 is that the mass of additive A in S4 is 20g, which is 50g less than that in Example 1. Other process parameters and operating conditions are exactly the same as those in Example 1.

[0088] Comparative Example 3

[0089] This comparative example provides a method for copper enrichment and recovery by adding an additive during the flameless combustion of copper-containing sludge. The difference between this method and Example 1 is that the mass of additive C in S4 is 103g, which is 50g more than in Example 1. Other process parameters and operating conditions are exactly the same as in Example 1.

[0090] Comparative Example 4

[0091] This comparative example provides a method for copper enrichment and recovery by adding an additive during the flameless combustion of copper-containing sludge. The difference between this method and Example 1 is that the mass of additive C in S4 is 3g, which is 50g less than that in Example 1. Other process parameters and operating conditions are exactly the same as those in Example 1.

[0092] Plot the standard curve: Transfer 0.00 ml, 1.00 ml, 2.00 ml, 3.00 ml, 4.00 ml, and 5.00 ml of 200 μg / ml copper standard solution, and measure their absorbance sequentially at a wavelength of 324.8 nm using an atomic absorption spectrophotometer to plot the standard curve.

[0093] Determination of copper content in sludge: 1.000 g of dried sludge was screened and placed in a polytetrafluoroethylene (PTFE) crucible. The crucible was placed on a hot plate, and 80 wt.% nitric acid was added. Heating was continued until nearly dry, then 40 wt.% HF and 70 wt.% perchloric acid were added. Heating was continued until nearly dry. The crucible was removed, and 10 wt.% nitric acid was added to bring the volume to a final volume to obtain the sample to be tested. The absorbance of the sample was measured, and the results were used to determine the copper content in the sludge. The calculated copper content was 14.3 wt.%.

[0094] Leaching rate determination: The supernatant of the copper-containing leachate was taken and diluted to 50 mL. The concentration was determined by atomic absorption spectrometry and converted into the mass fraction of copper in the leachate. The leaching rate was obtained by comparing it with the copper content in the sludge. The test results are shown in Table 1.

[0095] Table 1. Test results of copper enrichment and recovery during the flameless combustion of copper-containing sludge in Examples 1-4 and Comparative Examples 1-4.

[0096]

[0097] As shown in Table 1, the leaching rates of Comparative Examples 1 and 2 decreased compared to Example 1. This is because in Comparative Example 1, the amount of additive A was excessive. Excessive additive A leads to overly strong reducing properties in the system, which may reduce impurity oxides (such as Fe2O3), causing the impurities to combine with copper, increasing the impurity content in the copper alloy, and affecting the separation purity of copper. In Comparative Example 2, the amount of additive A was insufficient. The reducing and catalytic activity provided by additive A were insufficient, resulting in the incomplete reduction of copper oxides to metallic copper. Some copper remained in the slag as copper oxide, reducing the recovery rate. Compared to Example 1, the leaching rates of Comparative Examples 3 and 4 also decreased. In Comparative Example 3, the amount of additive C was excessive. Excessive molten salt may dissolve some impurity oxides, causing impurities to migrate into the copper alloy, reducing the recovery purity. At the same time, excessive molten salt may dilute the concentration of copper compounds in the reaction system, reducing the copper enrichment efficiency. In Comparative Example 3, the dosage of additive C was insufficient, the liquid medium coverage was uneven, the diffusion and sedimentation of copper compounds were hindered, and efficient recovery was difficult.

[0098] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for copper enrichment and recovery by adding additives during the flameless combustion of copper-containing sludge, characterized in that, Includes the following steps: S1, disperse chitosan and ferric nitrate nonahydrate in deionized water, adjust the pH to 8, add sodium tripolyphosphate and graphene oxide, and heat and keep warm to obtain additive A; S2, terephthalic acid is dispersed in the first part of DMF, and zirconium chloride and cerium nitrate hexahydrate are dispersed in the second part of DMF and then mixed with the terephthalic acid dispersion to obtain auxiliary agent B. S3, mix halide salt, potassium tetraborate and sodium fluoride, heat and keep warm and then cool, add ionic liquid, molybdenum carbide and iron boride and mix to obtain auxiliary agent C; S4, the dried and pulverized copper-containing sludge is mixed with additives A, B, and C in sequence with PVA solution to obtain a mixture. The mixture is then introduced with mixed gas and heated in stages to obtain slag product. S5 involves crushing the slag product and using a strong magnetic separator to separate the iron-based alloy. The copper alloy is then separated by a gravity separation device. The copper alloy is immersed in acid to obtain a copper-containing leachate, which is then extracted using an extractant to recover the copper.

2. The method for copper enrichment and recovery by adding an additive during the flameless combustion of copper-containing sludge according to claim 1, characterized in that, In S1, The mass ratio of chitosan, ferric nitrate nonahydrate, sodium tripolyphosphate, and graphene oxide is 80:15:7:

2.

3. The method for copper enrichment and recovery by adding an additive during the flameless combustion of copper-containing sludge according to claim 1, characterized in that, In S2, The mass ratio of terephthalic acid, zirconium chloride and cerium nitrate hexahydrate is 10:14:1.

5.

4. The method for copper enrichment and recovery by adding an additive during the flameless combustion of copper-containing sludge according to claim 1, characterized in that, In S3, The mass ratio of the halide salt, potassium tetraborate, sodium fluoride, ionic liquid, molybdenum carbide and iron boride is 24:5:3:4:(1-2):(1-2).

5. The method for copper enrichment and recovery by adding an additive during the flameless combustion of copper-containing sludge according to claim 1, characterized in that, In S3, The halide salts are LiCl, KCl, and NaCl in a mass ratio of 1:1:

1.

6. The method for copper enrichment and recovery by adding an additive during the flameless combustion of copper-containing sludge according to claim 1, characterized in that, In S4, The mass ratio of the dried and pulverized copper-containing sludge, additive A, additive B and additive C is 1000:(7-10):(5-7):(4-6).

7. The method for copper enrichment and recovery by adding an additive during the flameless combustion of copper-containing sludge according to claim 1, characterized in that, In S4, The mass-to-volume ratio of the dried and pulverized copper-containing sludge to the PVA solution was 100g:(3-5)mL, and the mass fraction of the PVA solution was 1wt.%.

8. The method for copper enrichment and recovery by adding an additive during the flameless combustion of copper-containing sludge according to claim 1, characterized in that, In S4, The staged heating is as follows: in the first stage, the temperature is raised to 300°C at a rate of 10°C / min, the holding time is 40min, and the excess air coefficient is 1.

2. The second stage involves heating from 300℃ to 500℃ at a rate of 10℃ / min, holding for 30 minutes, and using an excess air coefficient of 1.

0. The process involves three stages: heating from 500℃ to 700℃ at a rate of 5℃ / min, holding for 50 minutes, and using an excess air coefficient of 0.

9. The process involves four stages: heating from 700℃ to 900℃ at a rate of 5℃ / min, holding for 60 minutes, and using an excess air coefficient of 0.

8.

9. The method for copper enrichment and recovery by adding an additive during the flameless combustion of copper-containing sludge according to claim 1, characterized in that, In S5, The acid solution is a 5 wt.% hydrochloric acid solution; The extractant is LIX984.

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