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

Abstract

The invention belongs to the field of sludge treatment, and provides a method for realizing copper enrichment and recovery by adding an auxiliary agent in a flameless combustion process of copper-containing sludge. According to the method, enrichment and recovery of copper are realized by combining preparation of a multifunctional additive with staged heating and subsequent separation processes, an additive A provides reducibility by using a nitrogen-containing carbon material generated by pyrolysis of chitosan, and an iron oxide catalyzes reduction of a copper compound; the auxiliary agent B regulates and controls the redox reaction through the oxygen vacancy of CeO2, and ZrO2 provides mechanical support; the auxiliary C promotes copper compound migration through a low-melting-point eutectic salt system, impurity oxides are removed at the same time, copper compound decomposition, migration and reduction are sequentially completed through staged heating, copper-rich slag is finally formed, iron impurities are removed through follow-up strong magnetic separation, copper alloy is enriched through reselection, copper-containing leachate is generated through acid leaching, copper ions are selectively extracted through an extracting agent, and the copper-rich slag is obtained. And finally, recycling of high-purity copper is achieved.

Description

Technical Field

[0001] The invention belongs to the field of sludge treatment and relates to a method for adding an auxiliary agent during the flameless combustion of copper-containing sludge to achieve copper enrichment and recovery. Background Art

[0002] Copper-containing sludge is a common solid waste generated during industrial production, primarily from industries such as electroplating, electronic scrap recycling, metallurgy, mining wastewater treatment, and the chemical industry. Copper-containing sludge is typically rich in metallic copper and its compounds, and is also doped with 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 the sludge in chemically bound or adsorbed forms, further complicating its treatment. With the rapid advancement of global industrialization and urbanization, the production of copper-containing sludge is increasing annually. According to relevant statistics, the total amount of copper-containing sludge generated globally each year has reached millions of tons. Improper treatment of this sludge not only wastes the metal resources it contains but also poses a serious threat to the environment. For example, unrecovered heavy metals in the sludge can leach into soil and water bodies, potentially harming ecosystems and human health. Therefore, how to treat and recycle valuable metal resources in copper-containing sludge has become an important direction of current resource technology research.

[0003] Currently, treatment methods for copper-containing sludge primarily include physical separation, hydrometallurgy, and pyrolysis and incineration. Physical separation methods use flotation, magnetic separation, and gravity separation to initially concentrate the metal components in the sludge, but are inefficient for recovering copper with smaller particles and complex binding structures. Hydrometallurgy is inefficient in separating inert components from the sludge, resulting in large amounts of waste residue. Pyrolysis and incineration also suffer from low copper enrichment efficiency, with copper often remaining in the slag as oxides or silicates, making further recovery difficult. Flameless combustion technology has recently gained increasing attention in the waste treatment and energy utilization sectors. This novel thermal treatment process, based on a controlled combustion process using a slightly reducing or slightly oxygen-enriched atmosphere, offers advantages over traditional combustion technologies, such as more uniform heat release and higher thermal efficiency, achieved through atmosphere control and the introduction of heterogeneous catalysts. Furthermore, the introduction of molten salts, organic modifiers, or oxide catalysts creates a heterogeneous reaction system involving molten salts, solid phases, and gas phases, promoting the separation and enrichment of metal components. The resource utilization of copper-containing sludge is an important part of achieving a circular economy and green development. The development of 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] In response to the shortcomings of the prior art, the present invention aims to provide a method for copper enrichment and recovery by adding additives during the flameless combustion of copper-containing sludge. Additives A, B and C are prepared, the copper-containing sludge is mixed with the additives and then pressed into tablets. In a staged heating process, volatile components are removed, copper compounds are decomposed and reduced, and impurity oxides are separated. Finally, copper-rich slag is formed. Iron-based alloys are removed by strong magnetic separation, copper alloys are separated by gravity separation equipment, and copper is further converted into a copper ion solution using acid leaching and extraction technology. Copper is selectively recovered using an extractant, thereby meeting the needs of actual production.

[0005] To achieve this object, the present invention adopts the following technical solutions:

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

[0007] S1, dispersing chitosan and ferric nitrate nonahydrate in deionized water, adjusting the pH to 8, adding sodium tripolyphosphate and graphene oxide, and heating and keeping warm to obtain additive A;

[0008] S2, dispersing terephthalic acid in the first portion of DMF, dispersing zirconium chloride and cerium nitrate hexahydrate in the second portion of DMF, and then mixing with the terephthalic acid dispersion to react and obtain additive B;

[0009] S3, mixing a halide salt, potassium tetraborate and sodium fluoride, heating and keeping the mixture, and then cooling the mixture, adding an ionic liquid, molybdenum carbide and iron boride to obtain an additive C;

[0010] S4, mixing the dried and crushed copper-containing sludge with additives A, B, C and PVA solution in sequence to obtain a mixed material, introducing a mixed gas and heating in stages to obtain a slag product;

[0011] S5, after crushing the slag product, use a strong magnetic separator to separate the iron-based alloy, separate the copper alloy through gravity separation equipment, immerse the copper alloy in acid solution to obtain copper-containing leachate, and use an extractant to recover copper.

[0012] The method specifically includes:

[0013] S1, dispersing chitosan and ferric nitrate nonahydrate in deionized water, heating and stirring to dissolve, adjusting the pH to 8, then adding sodium tripolyphosphate and graphene oxide dispersion, mixing evenly, drying and grinding, and adjusting the temperature to a first temperature under a nitrogen atmosphere to obtain an additive A;

[0014] S2, dispersing terephthalic acid in the first portion of DMF, dispersing zirconium chloride and cerium nitrate hexahydrate in the second portion of DMF, and then mixing with the terephthalic acid dispersion. After uniform mixing, the mixture is transferred to a polytetrafluoroethylene-lined autoclave, and the temperature is adjusted to the second temperature for reaction. After the reaction is completed, the mixture is centrifuged and washed, and the mixture is placed under a nitrogen atmosphere, and the temperature is adjusted to the third temperature for insulation to obtain additive B;

[0015] S3, mixing the halide salt, potassium tetraborate and sodium fluoride, adjusting the temperature to the fourth temperature under a nitrogen atmosphere and keeping the temperature, then quickly pouring it into a metal mold to cool, grinding it after cooling, adding the ionic liquid, molybdenum carbide and iron boride, and drying it to obtain the additive C;

[0016] S4, sequentially mixing the dried and crushed copper-containing sludge with additives A, B, C, and PVA solution, pressing the mixture into tablets and drying it to obtain a mixed material, introducing a mixed gas into the mixture and heating it in stages, continuously introducing nitrogen after the heating is completed, and naturally cooling the mixture to obtain a slag product;

[0017] S5, after crushing the slag product, use a strong magnetic separator to separate the iron-based alloy, separate the copper alloy through gravity separation equipment, immerse the copper alloy in acid solution to obtain copper-containing leachate, and use an extractant to recover copper.

[0018] Chitosan is a natural polysaccharide with abundant hydroxyl and amino groups in its molecular structure. These multifunctional groups not only make chitosan highly chemically reactive but also provide it with excellent coordination ability with metal ions. The amino groups, in particular, 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. As a typical Lewis acid, ferric ions readily coordinate with the amino and hydroxyl groups in chitosan molecules, forming a chitosan-iron complex. This complexation significantly enhances the material's metal ion-carrying capacity and provides it with metal active centers. During this process, the complexation between chitosan amino groups and ferric ions effectively stabilizes the iron ions by forming a stable complex, preventing unwanted precipitation or loss of the iron ions from the solution. The resulting chitosan-iron complex not only exhibits excellent chemical stability but also converts into functional iron oxides during subsequent heat treatment, imparting magnetic and catalytic activity to the material. These functional properties play a key role in the subsequent treatment of copper-containing sludge: First, the active sites on the surface of the iron oxide can undergo chemical adsorption or surface complexation with copper ions or copper compounds, thereby significantly improving the copper enrichment efficiency; second, the magnetism of the iron oxide provides a physical basis for the subsequent effective separation of copper from other impurities through magnetic separation. Under alkaline conditions, the amino groups of chitosan are gradually deprotonated, enhancing its electron donor capacity and thus improving its complexation efficiency with trivalent iron ions. At the same time, some trivalent iron ions will undergo hydrolysis under alkaline conditions to form Fe(OH)3 precipitates. Fe(OH)3 is an important precursor for the formation of iron oxides. During the subsequent high-temperature heat treatment process, Fe(OH)3 decomposes and converts into functional iron oxides. The formation of this iron oxide not only improves the thermal stability of the material, but also gives it excellent catalytic properties and adsorption capacity, enabling it to significantly promote the reduction reaction and enrichment process of copper under high temperature conditions.

[0019] At the same time, the introduction of sodium tripolyphosphate further enhances the system's functionality. Sodium tripolyphosphate is a typical multidentate ligand that can complex with trivalent iron ions to form iron phosphates or other phosphorus-containing compounds. These compounds possess extremely high thermal stability and redox activity. During subsequent heat treatment, they can further decompose and react with iron compounds to form more complex iron phosphate structures. The formation of iron phosphates not only significantly enhances the material's adsorption capacity but also provides additional redox active sites, effectively promoting the reduction reaction of copper compounds in high-temperature environments. The presence of phosphate ions also modifies the local reaction environment, lowering the reduction activation energy of copper oxides and thus enabling efficient conversion of copper from an oxidized state to a metallic state. Furthermore, the high chemical stability of iron phosphates enables them to effectively capture copper ions or copper oxides, further improving copper enrichment efficiency. The introduction of graphene oxide provides another important path to enhance the material's performance. Graphene oxide is a two-dimensional layered carbon material with a rich surface rich in oxygen-containing functional groups such as hydroxyl and carboxyl groups. These functional groups can weakly interact with iron or other metal ions, enhancing the material's dispersion and uniformity. During the subsequent high-temperature heat treatment, the graphene oxide is partially reduced to reduced graphene oxide, which exhibits high electrical conductivity and chemical stability while forming a porous network structure. The high electrical conductivity of reduced graphene oxide acts as an electron donor during the copper reduction process, accelerating the transition from the oxidized state to the metallic state. Simultaneously, 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 reduced graphene oxide network enhances the mechanical strength and thermal stability of the composite material, ensuring its long-term use under subsequent 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 its surface further enhance its adsorption capacity for metal ions and its surface reactivity. Simultaneously, Fe(OH)3 or chitosan-iron complexes generate magnetic iron oxides during pyrolysis, enhancing the material's magnetic separation capabilities. Furthermore, reduced graphene oxide and carbonized chitosan together form a highly conductive and porous composite matrix. This composite matrix not only significantly enhances the material's adsorption and catalytic performance but also further improves copper enrichment efficiency through its high specific surface area and dispersibility. Through the complexation of chitosan, the reactivity of sodium tripolyphosphate, the conductivity and porous network formation of graphene oxide, and the synergistic effects of multiple functional materials during high-temperature heat treatment, additive A prepared by S1 is a multifunctional composite material. This material exhibits multiple functions: efficient copper ion adsorption, catalytic copper reduction, and copper enrichment through its magnetic and porous structure, providing critical support for the subsequent treatment of copper-containing sludge and copper recovery.

[0021] Terephthalic acid is a typical organic dicarboxylic acid molecule, which contains two highly reactive carboxyl groups in its molecular structure. These carboxyl groups can generate carboxyl groups by deprotonation under solvent thermal conditions. Carboxyl groups are excellent ligands with strong electron donor ability, which can stably form coordination bonds with empty orbitals of metal ions. This coordination effect enables terephthalic acid to combine with a variety of metal ions to form a metal organic framework with a highly ordered structure. In the present invention, zirconium chloride is used as the metal node material of the metal organic framework, and its main function is to provide Zr 4+ ions serve as structural centers. Zr 4+ It is a high-valent metal ion with a high coordination number and strong Lewis acidity. It can react with the carboxyl groups of multiple terephthalic acid molecules to form a zirconium-based MOF structure. This coordination effect not only gives MOF a three-dimensional porous network structure, but also significantly improves the thermal and chemical stability of the material, enabling it to maintain structural integrity under high temperature conditions. In addition, Zr 4+ The Lewis acidity provides a large number of surface active sites for the material, 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, which provides Ce 3+ ions and Zr 4+ Participate in the construction of MOF. 3+ The unique feature of this is its reversible redox behavior This property makes Ce 3+ In MOF, Ce not only acts as a structural node, but also introduces a redox active center. 3+ It reacts with terephthalic acid to form cerium-based MOF. 3+ The redox properties of the material give it excellent catalytic ability, which is further activated during the subsequent high-temperature heat treatment process, showing the Ce 3+ Converted into CeO2 (cerium oxide). Cerium oxide is an inorganic material with unique redox properties, and a large number of oxygen vacancies can be generated on its surface. Oxygen vacancies are areas where oxygen atoms are missing from the surface of CeO2. These sites have good chemical activity and can promote redox reactions by capturing oxygen atoms in the oxide. During the treatment of copper-containing sludge, oxygen vacancies can effectively react with copper oxides, promote the reduction of copper oxides, and convert them into metallic copper. This oxygen vacancy effect significantly improves the recovery efficiency of copper, making CeO2 an indispensable key component in the entire additive system. Under solvent thermal reaction conditions, the final product is a MOF constructed by zirconium and cerium, which has a highly ordered porous structure and a high specific surface area.

[0022] The prepared MOF material undergoes a high-temperature heat treatment process in a nitrogen atmosphere at 300-310°C. During this process, the organic ligand (terephthalic acid) of MOF decomposes to produce CO2 and a small amount of carbon residue. At the same time, the metal nodes of MOF undergo an inorganic transformation, and Zr 4+ and Ce 3+ They are converted into zirconium oxide and cerium oxide respectively. Zirconia is a highly stable inorganic material that maintains chemical inertness and physical stability at high temperatures, while providing mechanical support and maintaining the porous structure of the material. This characteristic of ZrO2 ensures the long-term service life of the material under high temperature conditions and provides a stable physical platform for the adsorption of copper compounds, further improving the enrichment capacity of the additive. Cerium oxide exhibits unique redox behavior during high temperature treatment. In Ce 3+ and Ce 4+ Due to the electron exchange between ZrO2 and CeO2, 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 the oxide, oxygen vacancies can effectively promote the reduction reaction of copper oxide, converting CuO or Cu2O into metallic copper. The realization of this process not only accelerates the reduction kinetics of copper but also reduces the activation energy of copper oxide reduction to a certain extent. The resulting additive B is a composite material composed mainly of ZrO2 and CeO2. It combines the high stability of ZrO2 with 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 in 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 technical foundation for achieving efficient and green copper resource recovery.

[0023] Halide salts melt at high temperatures to form a low-melting-point eutectic salt system. The formation of this eutectic system is attributed to the synergistic effect between ions of different halides, which significantly weakens the lattice energy of a single halide, thereby reducing the melting point of the overall system. Through this mechanism, the melting point of the molten salt system is usually lower than that of the pure component salt, which significantly reduces the energy consumption required for the reaction. In the present 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. The ionization of the molten salt system is one of its core functions. 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. The reduction in surface energy makes the crystal structure of copper oxide easier to destroy, thereby promoting its chemical contact with other components. This solubility-promoting effect plays a key role in the reduction of copper oxide 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 with other highly active metal ions, it is easier to preferentially undergo reduction reaction. In addition, Cl in the molten salt - The ions can form stable complexes with copper ions. The formation of these complexes further reduces the chemical potential of copper ions, thereby improving their mobility and reactivity. Through the stabilization of the complexes, the dispersibility 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 copper enrichment effect, enabling the effective separation of copper from impurities.

[0024] Potassium tetraborate decomposes under high temperature conditions to form boron oxide (B2O3). B2O3 is a strongly acidic oxide with a significant fluxing effect. The introduction of B2O3 further reduces the viscosity and melting point of the molten salt system, while improving the fluidity and uniformity of the molten salt. This fluidity optimizes the contact efficiency of the reactants, allowing the copper compound to react quickly and fully with other components in the molten salt. In addition, B2O3 has a high chemical affinity and can interact stably with the copper compound through chemical adsorption or complexation, further enhancing the selective separation ability of copper. This adsorption not only stabilizes the copper compound 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 the oxides in the system, boron oxide can accelerate the reduction process of copper oxide.

[0025] The introduction of sodium fluoride further optimizes the chemical environment of the molten salt system. As a highly electronegative halide, its fluoride ions have high chemical reactivity. In a high-temperature molten system, fluoride ions can react with copper compounds or other metal oxides to form volatile or low-melting-point fluorides. These fluorides either escape as gaseous matter or dissolve in the molten salt, thereby achieving efficient separation of impurity oxides, reducing the interference of impurities in 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. The complexes further enhance the mobility and reactivity of copper by reducing 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, the halide salts, potassium tetraborate, and sodium fluoride work synergistically to form a low-viscosity, highly active molten system. This system provides an ideal reaction medium for copper mass transfer, migration, and enrichment. The halide salts reduce the surface energy of copper oxides through ionization, promoting their reduction. Potassium tetraborate further optimizes the fluidity of the system by generating boron oxides and enhances copper separation selectivity through adsorption and redox regulation. Sodium fluoride selectively reacts with impurities and copper compounds, improving copper enrichment efficiency and reducing impurity interference.

[0026] The main components of copper-containing sludge are copper compounds and other impurity oxides. Copper compounds are the target of enrichment, while impurity oxides are easily eutectic or mixed with copper compounds, affecting the selective recovery of copper. Additive A is a chitosan-iron composite material that combines the porous adsorption of chitosan, the magnetism of iron oxides, and the reducibility of nitrogen-containing carbon materials produced by high-temperature pyrolysis. During the heat treatment process, the iron oxides in additive A can catalyze the selective reduction of copper and achieve magnetic separation in the subsequent slag treatment stage. Additive B is a composite material that has oxygen vacancies and a stable porous structure through high-temperature treatment. The oxygen vacancies on the CeO2 surface can participate in the redox cycle. ZrO2 captures oxygen atoms in the oxides, promoting the reduction of copper oxides. ZrO2 provides mechanical support at high temperatures, maintaining the material's physical structure and ensuring uniform distribution of the additive during the enrichment process. 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, reducing the reaction activation energy. Potassium tetraborate reduces the viscosity of the molten salt system, improving the contact efficiency between copper compounds and other components, while also stabilizing copper compounds through adsorption and enhancing separation selectivity. Sodium fluoride reacts with impurity oxides to form volatile or low-melting-point fluorides, effectively removing impurities.

[0027] During the first heating stage, at temperatures below 300°C, the physically adsorbed water and some chemically bound water remaining in the copper-containing sludge begin to be gradually removed. During this process, the water evaporates into a gaseous state, helping to reduce the humidity in the system and prevent subsequent interference of high-temperature water vapor with the copper oxides. Simultaneously, low-molecular-weight organic matter that may be present in the copper-containing sludge undergoes thermal cracking or oxidative decomposition during this stage, generating volatile small molecules. Polyvinyl alcohol, acting as a binder, decomposes upon heating, producing a carbonaceous residue. This carbonaceous residue serves as an important electron donor for the subsequent reduction of the copper oxides, providing a reducing atmosphere for this process under high-temperature conditions. The chitosan in additive A decomposes during this stage, releasing small-molecule gases and simultaneously carbonizing into a porous nitrogen-containing carbon material. The nitrogen-containing carbon material is rich in active sites on its surface, enabling selective adsorption of copper compounds and providing a reaction platform for the subsequent reduction reaction. Furthermore, an excess air coefficient of 1.2 indicates a slight excess of oxygen in the atmosphere during this stage, creating a slightly oxidizing environment that facilitates the complete decomposition of organic impurities and partially oxidizes sulfides, minimizing their interference with subsequent reactions. During the second stage of heating, some copper compounds begin to decompose, forming copper oxide or copper suboxide. The CeO₂ in additive B begins to generate oxygen vacancies during this stage, demonstrating redox activity. Oxygen vacancies are sites in the CeO₂ crystal where oxygen atoms are missing. These sites are highly chemically active and can capture oxygen atoms within the system. Through the generation of these oxygen vacancies, CeO₂ enhances its redox regulation of copper oxides and provides active adsorption sites for copper compounds. The halide salt in additive C gradually melts during this stage, forming a low-melting-point, highly fluid eutectic salt system. The molten salt enhances the solubility and mobility of copper compounds through ionization, while also providing a liquid medium for copper enrichment. An excess air coefficient of 1.0 indicates a neutral redox environment during this stage. This atmosphere promotes the decomposition of copper compounds while preventing overoxidation, maintaining CuO or Cu₂O as the primary form. During the three-stage heating process, copper oxides begin to react with the carbonaceous residue, initially reducing them to metallic copper. Controlled by the redox atmosphere, the reaction rate accelerates with increasing temperature. At this stage, the nitrogen-containing carbon material in Additive A is rich in electron donors, further promoting the copper reduction kinetics. The halide salt in Additive C completely melts during this stage, forming a highly fluid liquid system that provides an ideal medium for the migration and diffusion of copper compounds. Sodium fluoride reacts with impurity oxides to form volatile or low-melting fluorides, gradually removing impurities from the system. Oxygen vacancies in CeO₂ are further enhanced during this stage, interacting with the CuO or Cu₂O surface, accelerating the redox process and ensuring the efficient conversion of copper compounds to metallic copper. An excess air coefficient of 0.9 indicates a slightly reducing redox environment during this stage, ensuring partial reduction of copper oxides while avoiding side reactions that occur under completely anoxic conditions.In the four-stage heating process, copper oxide is reduced to metallic copper in the range of 700-900℃. The carbonaceous residues produced by the decomposition of additives A and PVA, the oxygen vacancies of CeO2 in 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 high density in the molten salt system, metallic copper gradually settles to the bottom of the melt to form a copper-rich metal layer. The impurity oxides completely react with the molten salt at this stage to form a stable slag network structure. Boron oxide further improves the separation efficiency of impurities by regulating the viscosity of the molten salt. The excess air coefficient of 0.8 provides a significant reducing atmosphere to prevent the secondary oxidation of copper while ensuring the complete stabilization of the 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 volume ratio of chitosan to deionized water is 4 g:25 mL.

[0030] In some optional 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, and other unlisted temperatures within this temperature range are also applicable.

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

[0032] As a preferred technical solution 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 volume ratio of the terephthalic acid to the first portion of DMF is 1 g:10 mL.

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

[0035] In some optional 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, and other unlisted temperatures within this temperature range are also applicable.

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

[0037] In some optional 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, and other unlisted temperatures within this temperature range are also applicable.

[0038] In some optional embodiments, the third temperature insulation time is 1-2h, 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 is not limited to the listed times, and other unlisted times within the 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 salts are LiCl, KCl and NaCl in a mass ratio of 1:1:1.

[0041] In some optional 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, and other unlisted temperatures within this temperature range are also applicable.

[0042] In some optional embodiments, the insulation time of the fourth temperature is 50-60min, for example, it can be 50min, 51min, 52min, 53min, 54min, 55min, 56min, 57min, 58min, 59min or 60min, but is not limited to the listed times, and other unlisted times within the 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 crushed 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 volume ratio of the dried and crushed 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 optional embodiments, the mixed gas is nitrogen and air, the nitrogen flow rate is 0.7 L / min, and the air flow rate is 0.1 L / min.

[0046] In some optional embodiments, the stage heating is as follows: in the first stage, the temperature is raised to 300° C., the heating rate is 10° C. / min, the holding time is 40 min, and the excess air coefficient is 1.2;

[0047] In the second stage, the temperature was raised from 300°C to 500°C at a heating rate of 10°C / min, the holding time was 30 min, and the excess air coefficient was 1.0;

[0048] The third stage was heating from 500°C to 700°C at a heating rate of 5°C / min, holding time of 50min, and excess air coefficient of 0.9;

[0049] In the fourth stage, the temperature was raised from 700°C to 900°C, the heating rate was 5°C / min, the holding time was 60min, and the excess air coefficient was 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 realizing synergistic effects in the staged heating process, the reduction, migration, and enrichment processes of copper compounds are significantly optimized. The nitrogen-containing carbon material and iron oxide in additive A provide strong reducing properties and catalytic activity. Additive B regulates the redox reaction through the oxygen vacancies of CeO2. Additive C improves the migration efficiency of copper compounds through a low-melting-point eutectic salt system and effectively removes impurity oxides; (2) by designing additives and optimizing heat treatment conditions, the present 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. Fluoride and halide salts are used in additive C to form a low-melting-point eutectic system, which avoids the complexity of high-temperature slag treatment, reduces the difficulty of treating impurity oxides, and reduces environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 A flow chart of a method for adding an additive to achieve copper enrichment and recovery during the flameless combustion of copper-containing sludge is provided for Examples 1-4 of the present invention. DETAILED DESCRIPTION

[0054] The technical solutions of the present invention are described in detail below in conjunction with specific embodiments and their accompanying drawings. The embodiments described herein are specific embodiments of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be understood as limiting the embodiments of the present invention and the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the contents disclosed in the claims of this application and its specification, including technical solutions that adopt any obvious replacements and modifications to the embodiments described herein.

[0055] The chemical reagents used in the examples and comparative examples of the present invention are all commercially available products and have not been subjected to any further purification treatment.

[0056] Example 1

[0057] This embodiment provides a method for adding an additive to achieve copper enrichment and recovery during the flameless combustion of copper-containing sludge, the method specifically comprising the following steps:

[0058] S1, 800 g of chitosan and 150 g of ferric nitrate nonahydrate were dispersed in 5 L of deionized water, heated and stirred to dissolve, and the pH was adjusted to 8. Then, 70 g of sodium tripolyphosphate and 20 g of graphene oxide were added, mixed evenly, and dried and ground. Under a nitrogen atmosphere, the temperature was adjusted to 410°C and maintained for 2.2 h to obtain additive A;

[0059] S2, dispersing 10 g of terephthalic acid in 100 mL of DMF, then dispersing 14 g of zirconium chloride and 1.5 g of cerium nitrate hexahydrate in 100 mL of DMF and mixing with the terephthalic acid dispersion, transferring the mixture to a polytetrafluoroethylene-lined autoclave, adjusting the temperature to 130° C. and reacting for 21.2 h. After the reaction, centrifuging and washing the mixture, placing the mixture under a nitrogen atmosphere, adjusting the temperature to 306° C. and maintaining the temperature for 1.8 h, to obtain additive B;

[0060] S3, after mixing 240g of halide salt, 50g of potassium tetraborate and 30g of sodium fluoride, adjusting the temperature to 550°C under a nitrogen atmosphere and keeping the temperature for 51 minutes, quickly pouring it into a metal mold and cooling it. After cooling, grinding it and adding 40g of ionic liquid, 13g of molybdenum carbide and 19g of iron boride, and drying it to obtain additive C;

[0061] S4, 10kg of dried and crushed copper-containing sludge was mixed with 77g of additive A, 51g of additive B, 44g of additive C and 30mL of 1wt.% PVA solution in sequence, the mixture was pressed into tablets and dried to obtain a mixed material, the mixed material was introduced into the mixed gas and heated in stages, in the first stage, the temperature was raised to 300℃, the heating rate was 10℃ / min, the holding time was 40min, the excess air coefficient was 1.2, and in the second stage, the temperature was raised from 300℃ to 500℃, the heating rate was 10℃ / min, the holding time was 40min, and the excess air coefficient was 1.2. The heating rate is 10°C / min, the holding time is 30min, the excess air coefficient is 1.0, the three-stage heating is from 500°C to 700°C, the heating rate is 5°C / min, the holding time is 50min, the excess air coefficient is 0.9, and the four-stage heating is from 700°C to 900°C, the heating rate is 5°C / min, the holding time is 60min, the excess air coefficient is 0.8. After the heating is completed, nitrogen is continuously introduced and the slag product is obtained by natural cooling.

[0062] S5, after crushing the slag product, use a strong magnetic separator to separate the iron-based alloy, separate the copper alloy through gravity separation equipment, and obtain a copper-containing leachate from a 5wt.% hydrochloric acid solution of the copper alloy and use LIX984 to recover copper.

[0063] Example 2

[0064] This embodiment provides a method for adding an additive to achieve copper enrichment and recovery during the flameless combustion of copper-containing sludge, the method specifically comprising the following steps:

[0065] S1, 800 g of chitosan and 150 g of ferric nitrate nonahydrate were dispersed in 5 L of deionized water, heated and stirred to dissolve, and then the pH was adjusted to 8. Then, 70 g of sodium tripolyphosphate and 20 g of graphene oxide were added, mixed evenly, and dried and ground. Under a nitrogen atmosphere, the temperature was adjusted to 450°C and kept warm for 2.9 h to obtain additive A;

[0066] S2, dispersing 10 g of terephthalic acid in 100 mL of DMF, then dispersing 14 g of zirconium chloride and 1.5 g of cerium nitrate hexahydrate in 100 mL of DMF and mixing with the terephthalic acid dispersion, transferring the mixture to a polytetrafluoroethylene-lined autoclave, adjusting the temperature to 139° C. and reacting for 20.3 h. After the reaction, centrifuging and washing the mixture, placing the mixture under a nitrogen atmosphere, adjusting the temperature to 301° C. and maintaining the temperature for 1.4 h, to obtain additive B;

[0067] S3, after mixing 240g of halide salt, 50g of potassium tetraborate and 30g of sodium fluoride, adjusting the temperature to 510°C under a nitrogen atmosphere and keeping the temperature for 58 minutes, the mixture is quickly poured into a metal mold and cooled. After cooling, the mixture is ground and 40g of ionic liquid, 18g of molybdenum carbide and 16g of iron boride are added and mixed, and dried to obtain additive C;

[0068] S4, 10kg of dried and crushed copper-containing sludge was mixed with 95g of additive A, 59g of additive B, 58g of additive C and 38mL of 1wt.% PVA solution in sequence, the mixture was pressed into tablets and dried to obtain a mixed material, the mixed material was introduced into the mixed gas and heated in stages, in the first stage, the temperature was raised to 300℃, the heating rate was 10℃ / min, the holding time was 40min, the excess air coefficient was 1.2, and in the second stage, the temperature was raised from 300℃ to 500℃, the heating rate was 10℃ / min, the holding time was 40min, and the excess air coefficient was 1.2. The heating rate is 10°C / min, the holding time is 30min, the excess air coefficient is 1.0, the three-stage heating is from 500°C to 700°C, the heating rate is 5°C / min, the holding time is 50min, the excess air coefficient is 0.9, and the four-stage heating is from 700°C to 900°C, the heating rate is 5°C / min, the holding time is 60min, the excess air coefficient is 0.8. After the heating is completed, nitrogen is continuously introduced and the slag product is obtained by natural cooling.

[0069] S5, after crushing the slag product, use a strong magnetic separator to separate the iron-based alloy, separate the copper alloy through gravity separation equipment, and obtain a copper-containing leachate from a 5wt.% hydrochloric acid solution of the copper alloy and use LIX984 to recover copper.

[0070] Example 3

[0071] This embodiment provides a method for adding an additive to achieve copper enrichment and recovery during the flameless combustion of copper-containing sludge, the method specifically comprising the following steps:

[0072] S1, 800g chitosan and 150g ferric nitrate nonahydrate were dispersed in 5L deionized water, heated and stirred to dissolve, and then the pH was adjusted to 8. Then, 70g sodium tripolyphosphate and 20g graphene oxide were added, mixed evenly, and dried and ground. Under a nitrogen atmosphere, the temperature was adjusted to 420°C and kept warm for 2.4h to obtain additive A;

[0073] S2, dispersing 10 g of terephthalic acid in 100 mL of DMF, then dispersing 14 g of zirconium chloride and 1.5 g of cerium nitrate hexahydrate in 100 mL of DMF and mixing with the terephthalic acid dispersion, transferring the mixture to a polytetrafluoroethylene-lined autoclave, adjusting the temperature to 137° C. and reacting for 21.8 h. After the reaction, centrifuging and washing the mixture, placing the mixture under a nitrogen atmosphere, adjusting the temperature to 309° C. and maintaining the temperature for 1.1 h, to obtain additive B;

[0074] S3, after mixing 240g of halide salt, 50g of potassium tetraborate and 30g of sodium fluoride, adjusting the temperature to 590°C under a nitrogen atmosphere and keeping the temperature for 53 minutes, the mixture is quickly poured into a metal mold and cooled. After cooling, the mixture is ground and 40g of ionic liquid, 16g of molybdenum carbide and 14g of iron boride are added and mixed, and dried to obtain additive C;

[0075] S4, 10 kg of dried and crushed copper-containing sludge was 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 in sequence, the mixture was pressed into tablets and dried to obtain a mixture, the mixture was introduced into a mixed gas and heated in stages, in the first stage, the temperature was raised to 300 ° C, the heating rate was 10 ° C / min, the holding time was 40 min, the excess air coefficient was 1.2, and in the second stage, the temperature was raised from 300 ° C to 500 ° C, the heating rate was 10 ° C / min, the holding time was 40 min, and the excess air coefficient was 1.2. The heating rate is 10°C / min, the holding time is 30min, the excess air coefficient is 1.0, the three-stage heating is from 500°C to 700°C, the heating rate is 5°C / min, the holding time is 50min, the excess air coefficient is 0.9, and the four-stage heating is from 700°C to 900°C, the heating rate is 5°C / min, the holding time is 60min, the excess air coefficient is 0.8. After the heating is completed, nitrogen is continuously introduced and the slag product is obtained by natural cooling.

[0076] S5, after crushing the slag product, use a strong magnetic separator to separate the iron-based alloy, separate the copper alloy through gravity separation equipment, and obtain a copper-containing leachate from a 5wt.% hydrochloric acid solution of the copper alloy and use LIX984 to recover copper.

[0077] Example 4

[0078] This embodiment provides a method for adding an additive to achieve copper enrichment and recovery during the flameless combustion of copper-containing sludge, the method specifically comprising the following steps:

[0079] S1, 800g chitosan and 150g ferric nitrate nonahydrate were dispersed in 5L deionized water, heated and stirred to dissolve, and then the pH was adjusted to 8. Then, 70g sodium tripolyphosphate and 20g graphene oxide were added, mixed evenly, and dried and ground. Under a nitrogen atmosphere, the temperature was adjusted to 440°C and kept for 2.6h to obtain additive A;

[0080] S2, dispersing 10 g of terephthalic acid in 100 mL of DMF, then dispersing 14 g of zirconium chloride and 1.5 g of cerium nitrate hexahydrate in 100 mL of DMF and mixing with the terephthalic acid dispersion, transferring the mixture to a polytetrafluoroethylene-lined autoclave, adjusting the temperature to 135° C. and reacting for 20.7 h. After the reaction, centrifuging and washing the mixture, placing the mixture under a nitrogen atmosphere, adjusting the temperature to 304° C. and maintaining the temperature for 1.7 h, to obtain additive B;

[0081] S3, after mixing 240g of halide salt, 50g of potassium tetraborate and 30g of sodium fluoride, adjusting the temperature to 530°C under a nitrogen atmosphere and keeping the temperature for 57 minutes, the mixture is quickly poured into a metal mold and cooled. After cooling, the mixture is ground and 40g of ionic liquid, 14g of molybdenum carbide and 12g of iron boride are added and mixed, and dried to obtain additive C;

[0082] S4, 10kg of dried and crushed copper-containing sludge was mixed with 70g of additive A, 62g of additive B, 53g of additive C and 42mL of 1wt.% PVA solution in sequence, the mixture was pressed into tablets and dried to obtain a mixture, the mixture was introduced into the mixed gas and heated in stages, in the first stage, the temperature was raised to 300℃, the heating rate was 10℃ / min, the holding time was 40min, the excess air coefficient was 1.2, and in the second stage, the temperature was raised from 300℃ to 500℃, the heating rate was 10℃ / min, the holding time was 40min, and the excess air coefficient was 1.2. The heating rate is 10°C / min, the holding time is 30min, the excess air coefficient is 1.0, the three-stage heating is from 500°C to 700°C, the heating rate is 5°C / min, the holding time is 50min, the excess air coefficient is 0.9, and the four-stage heating is from 700°C to 900°C, the heating rate is 5°C / min, the holding time is 60min, the excess air coefficient is 0.8. After the heating is completed, nitrogen is continuously introduced and the slag product is obtained by natural cooling.

[0083] S5, after crushing the slag product, use a strong magnetic separator to separate the iron-based alloy, separate the copper alloy through gravity separation equipment, and obtain a copper-containing leachate from a 5wt.% hydrochloric acid solution of the copper alloy and use LIX984 to recover copper.

[0084] Comparative Example 1

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

[0086] Comparative Example 2

[0087] This comparative example provides a method for copper enrichment and recovery by adding an auxiliary agent during the flameless combustion of copper-containing sludge. The difference between this method and Example 1 is that the mass of auxiliary agent A in S4 is 20 g, which is 50 g less than that in Example 1. The 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 103 g, which is 50 g more than that in Example 1. The other process parameters and operating conditions are exactly the same as those in Example 1.

[0090] Comparative Example 4

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

[0092] Draw a standard curve: Pipette 0.00ml, 1.00ml, 2.00ml, 3.00ml, 4.00ml, and 5.00ml of a 200μg / ml copper standard solution, use an atomic absorption spectrophotometer to measure their absorbance at a wavelength of 324.8nm in sequence, and draw a standard curve.

[0093] Determine the copper content of sludge: After drying, sieve the sludge through a mesh and weigh 1.000 g. Place the sludge in a polytetrafluoroethylene crucible. Place the crucible on a hot plate and add 80 wt.% nitric acid. Heat until nearly dry, then stop heating. Add 40 wt.% HF and 70 wt.% perchloric acid. Heat until nearly dry. Remove the crucible and add 10 wt.% nitric acid. Constant volume is obtained to obtain the sample to be tested. Measure the absorbance of the sample and substitute it into the standard curve equation. The copper content of the sludge is 14.3 wt.%.

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

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

[0096]

[0097] As shown in Table 1, compared with Example 1, the leaching rates of Comparative Example 1 and Comparative Example 2 all decrease. This is because, in Comparative Example 1, auxiliary agent A is excessive, and excessive addition of auxiliary agent A will cause the reducibility in the system to be too strong, and impurity oxides (such as Fe2O3) may be reduced, so that impurities are combined with copper, and the content of impurities in the copper alloy is increased, affecting the separation purity of copper. In Comparative Example 2, the amount of auxiliary agent A is insufficient, and the reducibility and catalytic activity provided by auxiliary agent A are insufficient, resulting in copper oxide being unable to be completely reduced to metallic copper, and a part of copper will remain in the slag in the form of copper oxide, and the recovery rate is reduced. Compared with Example 1, the leaching rates of Comparative Example 3 and Comparative Example 4 all decrease. In Comparative Example 3, the amount of auxiliary agent C is too much, and molten salt may dissolve part of the impurity oxide too much, causing impurities to migrate into the copper alloy, reducing the recovery purity, and excessive molten salt may dilute the copper compound concentration in the reaction system, so that the enrichment efficiency of copper is reduced. In Comparative Example 3, the amount of additive C added was insufficient, the coverage of the liquid medium was uneven, the diffusion and sedimentation of the copper compound 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 thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for copper enrichment and recovery by adding an auxiliary agent during the flameless combustion of copper-containing sludge, characterized in that: The steps include: S1, dispersing chitosan and ferric nitrate nonahydrate in deionized water, adjusting the pH to 8, adding sodium tripolyphosphate and graphene oxide, and heating and keeping warm to obtain additive A; S2, dispersing terephthalic acid in the first portion of DMF, dispersing zirconium chloride and cerium nitrate hexahydrate in the second portion of DMF, and then mixing with the terephthalic acid dispersion to react and obtain additive B; S3, mixing a halide salt, potassium tetraborate and sodium fluoride, heating and keeping the mixture, and then cooling the mixture, adding an ionic liquid, molybdenum carbide and iron boride to obtain an additive C; S4, mixing the dried and crushed copper-containing sludge with additives A, B, C and PVA solution in sequence to obtain a mixed material, introducing a mixed gas and heating in stages to obtain a slag product; S5, after crushing the slag product, use a strong magnetic separator to separate the iron-based alloy, separate the copper alloy through gravity separation equipment, immerse the copper alloy in acid solution to obtain copper-containing leachate, and use an extractant to recover copper.

2. The method for copper enrichment and recovery by adding an auxiliary agent during the flameless combustion of copper-containing sludge according to claim 1, characterized in that: In S1, The mass ratio of the 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 auxiliary agent during the flameless combustion of copper-containing sludge according to claim 1, characterized in that: In S2, The mass ratio of the terephthalic acid, zirconium chloride and cerium nitrate hexahydrate is 10:14:1.

5.

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

8. The method for copper enrichment and recovery by adding an auxiliary agent during the flameless combustion of copper-containing sludge according to claim 1, characterized in that: In S4, The stage heating is as follows: in the first stage, the temperature is raised to 300°C, the heating rate is 10°C / min, the holding time is 40min, and the excess air coefficient is 1.2; In the second stage, the temperature was raised from 300°C to 500°C at a heating rate of 10°C / min, the holding time was 30 min, and the excess air coefficient was 1.0; The third stage was heating from 500°C to 700°C at a heating rate of 5°C / min, holding time of 50min, and excess air coefficient of 0.9; In the fourth stage, the temperature was raised from 700°C to 900°C, the heating rate was 5°C / min, the holding time was 60min, and the excess air coefficient was 0.

8.

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

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