A refining agent for removing impurities from scrap copper and a method for using the same
By using refining agents containing both iron and non-iron components, combined with oxygen blowing smelting and batch addition methods, the problem of removing impurities from scrap copper has been solved, achieving low-cost and high-efficiency impurity purification, especially with removal rates of over 70% for nickel, lead, and tin.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- INST OF MATERIALS HENAN ACAD OF SCI
- Filing Date
- 2025-01-17
- Publication Date
- 2026-05-15
AI Technical Summary
Existing refining agents for scrap copper are complex to prepare, costly, and difficult to effectively remove hard-to-separate impurity elements such as nickel, lead, and tin. Traditional refining agents have limited effectiveness in removing impurity elements.
Refining agents containing both iron and non-iron components, including SiO2 and Al2O3, are used. Through oxygen blowing smelting and batch addition, Fe2O3, SiO2, and Al2O3 react with impurity elements such as nickel, lead, and tin to generate stable compounds that enter the smelting slag, thereby purifying the impurities.
It achieves low-cost and efficient simultaneous removal of impurities such as nickel, lead, and tin from waste copper, reducing the impurity content in the product to the ppm level. The refining agent is readily available and environmentally friendly, and it is suitable for the simultaneous removal of multiple impurity elements.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of waste copper refining and impurity removal technology, and specifically discloses a refining agent for waste copper impurity removal and its application method. Background Technology
[0002] Scrap copper comes from a wide range of sources, contains many types of impurities, and exhibits a large fluctuation range. How to remove these impurities to a reasonable range is a crucial issue facing the recycled copper industry. Common refining agents used in pyrometallurgical refining of scrap copper include quartz sand, glass slag, lime, and soda ash. However, these traditional refining agents have limited effectiveness in removing impurities, especially for certain difficult-to-separate elements. Taking nickel as an example, nickel and copper can dissolve infinitely in solid solution through the substitution of atoms within the grains. When the nickel content in metallic copper is less than 0.3%, nickel exists in solid solution form within the copper matrix. During the smelting process, the oxidation of nickel is both slow and incomplete, and the generated NiO is distributed between the molten copper and the slag, making the separation and purification of nickel from the molten copper difficult.
[0003] Previous researchers have developed some novel refining agents for the removal and purification of impurities in scrap copper. However, these refining agents are often alloy or chemical products, with complex preparation processes and high costs. For example, the invention patent "A Refining Agent for Scrap Copper and Its Preparation Method and Application CN 110527860 B" discloses a refining agent for scrap copper that requires electrolytic copper, Cu-Mg alloy, Cu-B alloy, Cu-Ce alloy, Cu-Y alloy, Cu-Pr alloy, and Cu-La alloy as raw materials. The refining agent can only be prepared under high-purity inert atmosphere and high temperature conditions in a vacuum melting furnace. The raw material cost is high and the preparation process is complex. For example, the invention patent "An additive for removing nickel / bismuth from impure copper and its preparation method and application" (CN 115198100B) discloses an additive for removing nickel / bismuth from impure copper and its preparation method. The additive contains CaF2, MgF2 and CuF2. It requires adding raw materials containing CaF2, MgF2 and CuF2 or their substitutes into an induction furnace and melting them at 1400°C to synthesize the additive, or adding raw materials containing CaF2, metallic Mg and metallic Cu into an induction furnace and melting them at 1400°C to synthesize the additive. The raw material CaF2 can be fluorite, the raw material MgF2 can be magnesia fluoride, and CuF2 can be replaced by fluorocarbons, antimony pentafluoride or tin fluoride. Among these raw materials, CaF2 is relatively inexpensive and readily available, while MgF2 and CuF2 are not easy to obtain.
[0004] To address the challenges of removing or purifying difficult-to-separate impurities from existing waste copper, the complexity of refining agent preparation processes, and the high cost of refining agents, this invention is proposed. Summary of the Invention
[0005] The first technical problem this invention aims to solve is to provide a refining agent that is inexpensive, readily available, simple to prepare, environmentally friendly, and can effectively reduce the impurity content in scrap copper, especially the content of difficult-to-separate impurities. The second technical problem this invention aims to solve is to provide a method for applying this refining agent.
[0006] To solve the first technical problem mentioned above, the present invention provides a refining agent for removing impurities from waste copper. The refining agent includes an iron-containing component and a non-iron component. The valence state of the iron element in the iron-containing component is greater than or equal to 2. The non-iron component includes SiO2 and Al2O3. The mass content of the iron-containing component in the refining agent for removing impurities from waste copper is 10% to 96%.
[0007] As a preferred embodiment, the present invention provides a refining agent for removing impurities from waste copper, wherein the iron-containing component may be one or more of hematite, limonite, magnetite, siderite, and pyrite.
[0008] As a preferred embodiment, the present invention provides a refining agent for removing impurities from waste copper, wherein the non-ferrous components include gangue minerals containing SiO2 and Al2O3.
[0009] As a preferred embodiment, the present invention provides a refining agent for removing impurities from waste copper, wherein the sum of the mass percentages of the iron-containing components and the non-iron components SiO2 and Al2O3 in the refining agent is greater than 80%, preferably greater than 90%.
[0010] As one of the preferred embodiments, the present invention provides a refining agent for removing impurities from waste copper, wherein the refining agent contains an iron component with a mass content of 10% to 96%, preferably 15% to 96%.
[0011] As one of the preferred options, mined natural iron ore or iron concentrate and iron tailings obtained through beneficiation can be used as the refining agent.
[0012] To solve the second technical problem mentioned above, the present invention provides a method for applying a refining agent for removing impurities from scrap copper. After the scrap copper is heated and melted, a dried refining agent is added to the copper liquid. The melting temperature is controlled at 1100~1300℃. After oxygen blowing and melting, the slag is removed. The amount of refining agent used at one time is 0.1%~3% of the mass of the scrap copper.
[0013] This invention discloses a method for applying a refining agent for removing impurities from waste copper. For natural iron ore, it is crushed to less than or equal to 10mm and dried for later use. For iron concentrate and iron tailings obtained by manual sorting, they can be directly dried for later use.
[0014] The present invention discloses a method for applying a refining agent for removing impurities from waste copper, wherein the mass fraction of copper in the waste copper is greater than 90%, preferably greater than 98%.
[0015] The present invention discloses a method for applying a refining agent for removing impurities from scrap copper, wherein the amount of the refining agent used in a single application is 0.5% to 3% of the mass ratio of scrap copper, preferably 0.5% to 2%.
[0016] As one of the preferred embodiments, the present invention provides a method for applying a refining agent for removing impurities from waste copper, wherein the smelting temperature of the waste copper is 1150~1300℃, preferably 1150~1250℃, and the smelting time is 30~180min.
[0017] This invention discloses a method for applying a refining agent to remove impurities from waste copper. The refining agent can be added in batches. First, a refining agent with an iron content of less than 50% is added for initial impurity removal. After oxygen blowing, smelting, and slag removal, a refining agent with an iron content of greater than or equal to 50% is added for deep purification of impurities. After another oxygen blowing, smelting, and slag removal, purified copper liquid is obtained. In other words, the iron ore refining agent can be added in batches. Initially, a low-grade iron ore refining agent with an iron content of less than 50% is added for initial impurity removal. After oxygen blowing, smelting, and slag removal, a high-grade iron ore refining agent with an iron content of more than 50% is added for deep purification of impurities. After another oxygen blowing, smelting, and slag removal, purified copper liquid is obtained.
[0018] This invention discloses a method for applying a refining agent to remove impurities from waste copper. The refining agent is added to the molten waste copper to create slag 1-3 times. In this invention, insufficient refining agent results in a significantly weaker impurity removal effect, while excessive refining agent increases the cost of impurity removal. Furthermore, excessive use of high-grade refining agent may also lead to an increase in the iron content of impurities.
[0019] The batch addition method is particularly suitable for scrap copper with high impurity content of nickel, lead, and tin. For example, scrap copper with nickel, lead, and tin content greater than 200 ppm is well-suited for the batch addition method.
[0020] A refining agent for removing impurities from scrap copper using the above-mentioned technical solution and its application method are briefly described in the following technical principle: For nickel impurities that are difficult to separate, during the oxygen blowing smelting process of scrap copper, metallic nickel can be oxidized to NiO. However, NiO is distributed between the copper liquid and the slag, making separation and purification difficult. The iron-containing component in the refining agent is Fe2O3, or under oxygen blowing smelting conditions, it is easily converted to Fe2O3. NiO easily combines with Fe2O3 to form nickel-iron spinel NiO·Fe2O3, which enters the smelting slag. At the same time, NiO can also react with non-ferrous components in the refining agent. For example, it reacts with SiO2 to form nickel silicate NiO·SiO2, which enters the smelting slag, and reacts with Al2O3 to form nickel aluminate NiO·Al2O3, which also enters the smelting slag. Nickel compounds in the forms of NiO·Fe2O3, NiO·SiO2, and NiO·Al2O3 can exist stably in the smelting slag. After smelting, nickel can be removed from the scrap copper by skimming the slag. For impurities like lead and tin, during the oxygen blowing smelting process of scrap copper, metallic lead and tin can be oxidized to PbO and SnO, respectively. The SiO2 component in the refining agent can react with these to form PbO·SiO2 and SnO·SiO2, which then enter the smelting slag. For trace impurities of iron introduced by the refining agent, during the oxygen blowing smelting process, they are easily oxidized to FeO and react with the SiO2 component in the refining agent to form FeO·SiO2, which then enters the smelting slag. Therefore, the non-ferrous components in the refining agent also have the effect of purifying impurity iron (introduced by the refining agent).
[0021] 4Fe3O4 + O2(g) = 6Fe2O3
[0022] Fe₂O₃·nH₂O = Fe₂O₃ + nH₂O(g)
[0023] 4FeCO3 + O2(g) = 2Fe2O3 + 4CO2(g)
[0024] NiO+Fe2O3=NiO·Fe2O3 (NiFe2O4)
[0025] 2NiO+SiO2=2NiO·SiO2 (Ni2SiO4)
[0026] NiO+Al2O3=NiO·Al2O3 (NiAl2O4)
[0027] PbO + SiO₂ = PbO·SiO₂
[0028] SnO + SiO₂ = SnO·SiO₂
[0029] Using the refining agent and refining process designed in this invention, the Ni content in the product is less than or equal to 80 ppm, and after optimization, less than or equal to 50 ppm; the Pb content is less than or equal to 50 ppm; the Sn content is less than or equal to 50 ppm; and the Fe content is less than or equal to 50 ppm.
[0030] After optimization, using the refining agent and refining process designed in this invention, the Ni removal rate is greater than or equal to 70%, and the residual Ni in the product is less than 50 ppm.
[0031] After optimization, using the refining agent and refining process designed in this invention, the Pb removal rate is greater than or equal to 90%, and the residual Pb in the product is less than 50 ppm. In industrial applications, the higher the Pb content, the higher the Pb removal rate is achieved by using a batch addition method.
[0032] After optimization, using the refining agent and refining process designed in this invention, the Sn removal rate is greater than or equal to 90%, and the residual Sn in the product is less than 50 ppm. In industrial applications, the higher the Sn content, the higher the Sn removal rate can be achieved by using a batch addition method.
[0033] The advantages of this invention are:
[0034] 1) Refining agents can be obtained directly from nature or mineral processing plants. They are inexpensive, environmentally friendly, and extremely convenient for industrial application.
[0035] 2) The refining agent has a reasonable composition, which can simultaneously remove and purify multiple impurity elements such as nickel, lead, and tin from waste copper.
[0036] 3) The refining agent has a reasonable composition and a self-purifying effect, which can minimize the introduction of iron impurities;
[0037] 4) The refining agent is simple to prepare and flexible to use. It can be used in combination according to the impurity content in the scrap copper raw material or the different smelting stages. Detailed Implementation
[0038] The present invention will be further described below with reference to embodiments.
[0039] Example 1:
[0040] A refining agent for removing impurities from scrap copper is disclosed. The refining agent is iron ore mined from a mine, whose main iron components are hematite (80 wt.%) and limonite (15 wt.%), and whose main non-ferrous component is SiO2 (2 wt.%), with the balance being other impurities. The particle size is less than or equal to 10 mm. This iron ore does not require crushing and can be directly used as a refining agent for removing impurities from scrap copper after drying. After melting the scrap copper (the raw material contains 99.89 wt.% Cu), a refining agent at a mass ratio of 2.0 wt.% of the scrap copper is added, and oxygen blowing smelting is carried out. The smelting temperature is maintained at 1200℃ for 60 minutes. After smelting, the slag is removed to obtain a cleaned copper liquid. After reduction and deoxidation, the copper content in the copper liquid is 99.94 wt%. The changes in impurity element content before and after removing impurities from the scrap copper are shown in Table 1.
[0041]
[0042] Example 2:
[0043] A refining agent for removing impurities from scrap copper is disclosed. The refining agent is iron ore mined from a mine, whose main iron components are hematite (62 wt.%) and limonite (9 wt.%), and whose main non-ferrous components are SiO2 (10 wt.%) and Al2O3 (6 wt.%), with the balance being other impurities. The iron ore particle size is less than or equal to 30 mm. This iron ore, after being crushed to a particle size less than or equal to 10 mm, can be used as a refining agent for removing impurities from scrap copper. After melting the scrap copper (the raw material contains 99.89 wt.% Cu), a refining agent at a mass ratio of 2.0 wt.% of the scrap copper is added, and oxygen blowing smelting is performed. The smelting temperature is maintained at 1200℃ for 120 minutes. After smelting, the slag is removed to obtain a cleaned copper liquid. After reduction and deoxidation, the copper content in the copper liquid is 99.94 wt%. The changes in impurity element content before and after removing impurities from the scrap copper are shown in Table 2.
[0044]
[0045] Example 3:
[0046] A refining agent for removing impurities from scrap copper is disclosed. The refining agent is iron ore mined from a mine, whose main iron components are siderite (18 wt.%) and hematite (10 wt.%), and whose main non-ferrous components are SiO2 (35 wt.%) and Al2O3 (10 wt.%), with the balance being other impurities. The iron ore particle size is less than or equal to 40 mm. This iron ore, after being crushed to a particle size less than or equal to 10 mm, can be used as a refining agent for removing impurities from scrap copper. After melting the scrap copper (the raw material contains 99.89 wt.% Cu), a refining agent at a mass ratio of 2.0 wt.% of the scrap copper is added, and oxygen blowing smelting is carried out. The smelting temperature is maintained at 1200℃ for 180 minutes. After smelting, the slag is removed to obtain a cleaned copper liquid. After reduction and deoxidation, the copper content in the copper liquid is 99.93 wt%. The changes in impurity element content before and after removing impurities from the scrap copper are shown in Table 3.
[0047]
[0048] Example 4:
[0049] A refining agent for removing impurities from scrap copper is derived from iron concentrate obtained through mineral processing. Its main iron components are magnetite (80 wt.%) and hematite (10 wt.%), with SiO2 (6 wt.%) as the main non-ferrous component and other impurities as the balance. The particle size is less than or equal to 0.5 mm. This iron concentrate does not require grinding and can be directly used as a refining agent for removing impurities from scrap copper after drying. After melting the scrap copper (the raw material contains 99.89 wt.% Cu), a refining agent at a mass ratio of 1.0 wt.% of the scrap copper is added, followed by oxygen blowing smelting. The smelting temperature is maintained at 1250℃ for 120 minutes. After smelting, the slag is skimmed off to obtain a cleaned copper liquid. After reduction and deoxidation, the copper content in the copper liquid is 99.94 wt%. The changes in impurity element content before and after removing impurities from the scrap copper are shown in Table 4.
[0050]
[0051] Example 5:
[0052] A refining agent for removing impurities from scrap copper is disclosed. The refining agent consists of iron concentrate and iron tailings obtained from mineral processing. The iron concentrate mainly contains magnetite (80 wt.%) and hematite (10 wt.%), with SiO2 (6 wt.%) as the main non-ferrous component and a particle size of ≤0.5 mm, with the remainder being other impurities. The iron tailings mainly contain hematite (10 wt.%) and magnetite (5 wt.%), with SiO2 (62 wt.%) as the main non-ferrous component and the remainder being other impurities, with a particle size of ≤0.5 mm. This iron concentrate and iron tailings do not require grinding and can be directly used as a refining agent for removing impurities from scrap copper after drying. After melting scrap copper (the raw material contains 99.88 wt.% Cu), iron tailings (1.0 wt.% of the scrap copper) were added, and oxygen smelting was carried out at a temperature of 1250℃ for 90 minutes. After smelting, the slag was removed, and then iron concentrate (1.0 wt.% of the scrap copper) was added. Oxygen smelting was carried out again at a temperature of 1200℃ for 90 minutes. After smelting, the slag was removed, and the copper liquid obtained after impurity removal was obtained. After reduction and deoxidation, the copper content in the copper liquid was 99.94 wt%. The changes in the impurity element content before and after impurity removal of scrap copper are shown in Table 5.
[0053]
[0054] Example 6:
[0055] A refining agent for removing impurities from scrap copper is disclosed. The refining agent consists of iron concentrate and iron tailings obtained from mineral processing. The iron concentrate mainly contains magnetite (80 wt.%) and hematite (10 wt.%), with SiO2 (6 wt.%) as the main non-ferrous component and a particle size of ≤0.5 mm, with the remainder being other impurities. The iron tailings mainly contain hematite (10 wt.%) and magnetite (5 wt.%), with SiO2 (62 wt.%) as the main non-ferrous component and the remainder being other impurities, with a particle size of ≤0.5 mm. This iron concentrate and iron tailings do not require grinding and can be directly used as a refining agent for removing impurities from scrap copper after drying. After melting scrap copper (the raw material contains 99.72 wt.% Cu), 2.0 wt.% iron tailings were added, and oxygen smelting was carried out at a temperature of 1250℃ for 90 minutes. After smelting, the slag was removed, and then 2.0 wt.% iron concentrate was added, followed by oxygen smelting at a temperature of 1200℃ for 60 minutes. After smelting, the slag was removed again, and then 2.0 wt.% iron concentrate was added, followed by oxygen smelting at a temperature of 1200℃ for 60 minutes. After smelting, the slag was removed again, resulting in a purified copper liquid. After reduction and deoxidation, the copper content in the copper liquid was 99.93 wt%. The changes in impurity element content before and after impurity removal of scrap copper are shown in Table 6.
[0056]
[0057] Comparative Example 1:
[0058] The other conditions were the same as in Example 1, except that the amount of refining agent was 0.1%, and the contents of impurities Ni, Pb, Sn and Fe in the copper liquid after purification were 135ppm, 81ppm, 72ppm and 18ppm, respectively.
[0059] Comparative Example 2:
[0060] The other conditions are the same as in Example 1, except that the refining agent is composed of 50 wt.% quartz sand and 50 wt.% crushed glass, and the contents of impurities Ni, Pb, Sn and Fe in the copper liquid after impurity removal are 141 ppm, 26 ppm, 32 ppm and 14 ppm, respectively.
[0061] Comparative Example 3:
[0062] Other conditions were the same as in Example 1, except that the refining agent was chemically pure ferric oxide, and 2.0 wt.% of the refining agent was added. After impurity removal, the contents of impurities Ni, Pb, Sn and Fe in the copper liquid were 58 ppm, 88 ppm, 74 ppm and 36 ppm, respectively. By comparing Example 1 and Comparative Example 3, it was found that the effect of adding pure ferric oxide on removing Pb and Sn was generally poor, and the amount of Fe introduced was too high.
Claims
1. A method for applying a refining agent for removing impurities from waste copper, characterized in that: After the scrap copper is heated and melted, a dry refining agent is added to the molten copper. The smelting temperature is controlled at 1100~1300℃. After oxygen blowing smelting, the slag is skimmed off. The refining agent includes iron-containing components and non-iron components. The valence state of iron in the iron-containing components is greater than or equal to 2, and the non-iron components include SiO2 and Al2O3. The iron-containing component in the refining agent for removing impurities from waste copper has a mass content of 10% to 96%. The iron-containing component is selected from one or more of hematite, limonite, magnetite, siderite, and pyrite; the non-iron component includes gangue minerals containing SiO2 and Al2O3. The amount of refining agent used per application is 0.5% to 2% of the mass of scrap copper; The refining agent is added in batches. First, a refining agent with an iron content of less than 50% is added for preliminary impurity removal. After oxygen blowing and slag removal, a refining agent with an iron content of greater than or equal to 50% is added for deep purification of impurities. After oxygen blowing and slag removal again, purified copper liquid is obtained. The Fe content in the product is less than or equal to 50 ppm; The removal rate of Ni is greater than or equal to 70%, and the residual Ni in the product is less than 50 ppm. The removal rate of Pb is greater than or equal to 90%, and the residual Pb in the product is less than 50 ppm; The removal rate of Sn is greater than or equal to 90%, and the residual Sn in the product is less than 50 ppm.
2. The application method of the refining agent for removing impurities from waste copper according to claim 1, characterized in that: The refining agent contains more than 80% iron-containing components and more than 80% non-iron components such as SiO2 and Al2O3 by mass.
3. The application method of the refining agent for removing impurities from waste copper according to claim 1, characterized in that: The refining agent contains 15% to 96% iron by mass.
4. The application method of the refining agent for removing impurities from waste copper according to claim 1, characterized in that: The refined agent is the mined natural iron ore or the iron concentrate or iron tailings obtained through beneficiation.
5. The application method of the refining agent for removing impurities from waste copper according to claim 1, characterized in that: For natural iron ore, crush it to less than or equal to 10mm and dry it for later use. For iron concentrate and iron tailings obtained by artificial sorting, they can be dried directly for later use.
6. The application method of the refining agent for removing impurities from waste copper according to claim 1, characterized in that: The mass fraction of copper in the scrap copper is greater than 90%.
7. The application method of the refining agent for removing impurities from waste copper according to claim 1, characterized in that: The smelting temperature of the scrap copper is 1150~1300℃, and the smelting time is 30~180min.