Method for deeply removing nickel from scrap copper

Abstract

The invention belongs to the technical field of scrap copper refining and impurity removal, and particularly discloses a method for deeply removing nickel from scrap copper. The method comprises the following steps: melting scrap copper, firstly adding an impurity removal agent A to carry out primary impurity removal and slagging-off, and then adding dihydric phosphate to carry out deep impurity removal, so as to obtain a copper liquid with the nickel content of less than 30 ppm; the impurity removal agent A comprises an iron-containing component and a non-iron component, the valence state of an iron element in the iron-containing component is greater than or equal to 2, and the non-iron component comprises SiO2 and Al2O3. According to the method, firstly, the iron-containing minerals are used as an impurity removal agent A to rapidly remove impurities from the scrap copper, then dihydric phosphate is used as a deep impurity removal agent to deeply remove nickel, meanwhile, iron introduced during preliminary impurity removal is removed, and almost no new impurities are introduced. The method is simple in process, high in controllability, excellent in implementation effect and convenient for industrial application.

Description

Technical Field

[0001] The invention belongs to the technical field of refining and removing impurities from scrap copper, and specifically discloses a method for deep nickel removal from scrap copper. Background Art

[0002] my country's copper ore reserves account for only 3.97% of the world's total reserves, with a foreign dependence rate of more than 70% and a low level of resource security. The recycling of scrap copper has the advantages of low production cost, low energy consumption and low pollution, and is an effective way to alleviate the shortage of copper resources in my country. At present, according to the difference in the quality of scrap copper raw materials, its recycling methods can be divided into direct utilization and indirect utilization. The direct utilization method mainly adopts oxidation-reduction smelting, and the scrap copper is directly made into copper products such as copper rods, bars, wires, and plates after refining and impurities removal. It has the advantages of short process flow, simple equipment, high metal recovery rate, low energy consumption, and low cost. Due to the many types of impurity elements brought into the scrap copper raw materials, it is difficult to deeply purify the impurities, especially for the difficult-to-separate impurity nickel, which leads to the performance and quality stability of the recycled copper products cannot be guaranteed. The nickel in scrap copper mainly comes from nickel-plated copper and nickel-containing copper alloys. The harm of impurity nickel to the performance of copper materials is mainly manifested in: 1) reducing the conductivity of copper; 2) causing the brittleness of copper.

[0003] Nickel and copper both have face-centered cubic structures, and they can be infinitely soluble in each other by replacing atoms in the grains, so nickel has a high solubility in copper liquid. During the oxidation refining stage of scrap copper, since nickel has a similar affinity for oxygen as copper, the formed NiO is easily mixed in the copper liquid and is difficult to separate, especially for trace nickel impurities at the ppm level.

[0004] The present invention is proposed to solve the problem of the difficulty in removing the impurity element nickel from existing scrap copper, especially the difficulty in deep purification of trace nickel impurities. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for deep nickel removal from scrap copper to achieve high-quality recycling of scrap copper.

[0006] The invention discloses a method for deep nickel removal from scrap copper. The method comprises the following steps: firstly adding a de-impurity agent A to melt the scrap copper for preliminary de-impurity removal, removing slag, and then adding dihydrogen phosphate for deep de-impurity removal to obtain a copper liquid with a nickel content lower than 30 ppm; the de-impurity agent A comprises 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, and the non-iron component comprises SiO2 and Al2O3; the mass content of the iron-containing component in the de-impurity agent A is 10% to 96%; the single usage amount of the de-impurity agent A is 0.1% to 3% of the mass of the scrap copper, and the single usage amount of the dihydrogen phosphate is 0.1% to 2.5% of the mass of the scrap copper.

[0007] In industrial applications, after adding dihydrogen phosphate, oxidative smelting for a period of time and then slagging can effectively reduce the content of impurity element nickel in the copper liquid. Through multiple slagging, the trace nickel impurities can be deeply purified. The iron content in the resulting copper liquid is less than 10ppm.

[0008] Preferably, the copper mass fraction in the scrap copper is greater than 96%.

[0009] Preferably, the iron-containing component may be one or more of hematite, limonite, magnetite, siderite and pyrite.

[0010] Preferably, the non-ferrous components include gangue minerals containing SiO2 and Al2O3.

[0011] Preferably, the sum of the mass percentages of the iron-containing components and the non-iron components of SiO2 and Al2O3 in the impurity remover A is greater than 80%.

[0012] Preferably, the dihydrogen phosphate is selected from at least one of calcium dihydrogen phosphate, sodium dihydrogen phosphate and potassium dihydrogen phosphate. Among them, under the same dosage, the best impurity removal effect of dihydrogen phosphate is better than that of the prior art. This is also the first exploration of the present invention.

[0013] Preferably, the single dosage of the impurity remover A is 0.5% to 2% of the mass of the scrap copper, and the number of uses is 1 to 3 times.

[0014] Preferably, the single dosage of the dihydrogen phosphate is 0.5% to 2% of the mass of the scrap copper, more preferably 1% to 2%, and the number of uses is 1 to 3 times.

[0015] Preferably, when the impurity remover A is used for preliminary impurity removal, the smelting temperature is 1150-1300° C., and the oxidation smelting time is 0.5-3 h.

[0016] Preferably, when dihydrogen phosphate is added for deep impurity removal, the smelting temperature is 1150-1300°C, and the oxidation smelting time is 0.5-3 hours. In industrial applications, when dihydrogen phosphate is added for deep impurity removal, the single oxidation smelting time is 0.5-1 hour, which is conducive to improving production efficiency.

[0017] Through the treatment of the present invention, the trace nickel impurities can be deeply purified and the nickel content in the copper liquid can be reduced to below 30 ppm.

[0018] A method for deep nickel removal from scrap copper using the above technical solution, the technical principle of which is briefly described as follows: The present invention first uses iron-containing minerals as impurity remover A to quickly remove impurities from waste copper, and then uses dihydrogen phosphate as a deep impurity remover to deeply remove nickel, while also removing the iron introduced during the initial impurity removal. Taking CaH2PO4 refining agent as an example, a small portion of Cu in the waste copper solution is oxidized to Cu2O, and Ni is oxidized to NiO. Cu2O and NiO can react with CaH2PO4 to form a complex compound of CaO-Cu2O-NiO-P2O5 [Ca3(Cu,Ni)3(PO4)4, Ca 19 (Cu,Ni)2(PO4) 14 Similarly, Cu2O and NiO can react with NaH2PO4 to form complex compounds of Na2O-Cu2O-NiO-P2O5 [Na6(Cu,Ni)9(PO4)8, Na2(Cu,Ni)(PO3)4, etc.] which enter the slag phase, and Cu2O and NiO can react with KH2PO4 to form complex compounds of K2O-Cu2O-NiO-P2O5 [K2(Cu,Ni)(PO3)4, etc.] which enter the slag phase, and nickel in waste copper can be removed after slag removal. In addition, since impurity remover A, especially impurity remover A with a high iron content, easily introduces trace impurity iron into the copper liquid, the impurity iron can be oxidized to FeO during the oxygen blowing smelting process of the copper liquid. Taking CaH2PO4 refining agent as an example, FeO in the copper liquid can react with CaH2PO4 to form CaO-FeO-P2O5 complex compounds [Ca9Fe(PO4)7, etc.] and enter the slag phase. After slagging, the iron in the waste copper can be removed; in addition, after using dihydrogen phosphate refining agent to remove impurities, the residual phosphorus, calcium, sodium and potassium contents in the copper liquid are all less than 10ppm. It can be seen that dihydrogen phosphate can not only achieve deep purification of impurity nickel, but also achieve deep purification of impurity iron (introduced by impurity remover A) at the same time, and almost no new impurities are introduced. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with the embodiments.

[0020] Example 1: The main iron-containing components of impurity remover A are hematite (80wt.%) and limonite (15wt.%), and the main non-iron component is SiO2 (2wt.%). After the scrap copper is melted (the content of Cu in the raw material is 99.89wt.%), impurity remover A accounting for 3.0wt.% of the mass ratio of the scrap copper is added, oxygen blowing smelting is carried out, the smelting temperature is maintained at 1200℃, the smelting time is 60min, and the slag is skimmed after the smelting is completed; then calcium dihydrogen phosphate accounting for 2.0wt.% of the mass ratio of the scrap copper is added, and the slag is skimmed after oxidation smelting at 1200℃ for 60min to obtain the copper liquid after impurity removal, and the copper content in the copper liquid after reduction deoxidation is 99.95wt.%. The changes in the content of impurity elements before and after the impurity removal of the scrap copper are shown in Table 1.

[0021]

[0022] Embodiment 2: Compared with Example 1, the only difference is that the refining agent is sodium dihydrogen phosphate. The changes in the impurity element content of the scrap copper before and after impurity removal are shown in Table 2.

[0023]

[0024] Embodiment 3: Compared with Example 1, the only difference is that the refining agent is potassium dihydrogen phosphate. The changes in the impurity element content of the scrap copper before and after impurity removal are shown in Table 3.

[0025]

[0026] Embodiment 4: Impurity remover A is the iron concentrate and iron tailings obtained by ore dressing, wherein the main iron-containing components of the iron concentrate are magnetite (80wt.%) and hematite (10wt.%), and the main non-ferrous component is SiO2 (6wt.%); the main iron-containing components of the iron tailings are hematite (limonite) (10wt.%) and magnetite (5wt.%), and the main non-ferrous component is SiO2 (62wt.%). After the scrap copper is melted (the Cu content in the raw material is 99.72wt.%), iron tailings accounting for 2wt.% of the scrap copper mass ratio are added, oxygen blowing smelting is carried out, the smelting temperature is maintained at 1250℃, the smelting time is 90min, and the slag is removed after the smelting is completed; then iron concentrate accounting for 2wt.% of the scrap copper mass ratio is added, oxygen blowing smelting is carried out, the smelting temperature is maintained at 1200℃, the smelting time is 60min, and the slag is removed after the smelting is completed; then iron concentrate accounting for 2wt.% of the scrap copper mass ratio is added, oxygen blowing smelting is carried out, the smelting temperature is maintained at 1200℃, the smelting time is 60min, and the slag is removed after the smelting is completed; then calcium dihydrogen phosphate accounting for 2wt.% of the scrap copper mass ratio is added, and the smelting is oxidized at 1200℃ for 60min and then the slag is removed to obtain the copper liquid after impurities are removed, and the copper content in the copper liquid after reduction and deoxidation is 99.95wt.%. The changes in the impurity element content of scrap copper before and after impurity removal are shown in Table 4.

[0027]

[0028] Comparative Example 1: After the scrap copper was melted (the Cu content in the raw material was 99.89wt.%), quartz stone accounting for 2.0wt.% of the scrap copper mass ratio was added, and smelted at 1200℃ for 60min and then slag was removed; then quartz stone accounting for 2.0wt.% of the scrap copper mass ratio was added, and smelted at 1200℃ for 60min and then slag was removed to obtain the copper liquid after impurities were removed. After reduction and deoxidation, the copper content in the copper liquid was 99.94wt.%. The changes in the impurity element content of the scrap copper before and after impurities removal are shown in Table 5.

[0029]

[0030] Comparative Example 2: After the scrap copper was melted (the Cu content in the raw material was 99.89wt.%), calcium phosphate accounting for 2.0wt.% of the scrap copper mass ratio was added, and the scrap was removed after oxidation smelting at 1200℃ for 60min; sodium phosphate accounting for 2.0wt.% of the scrap copper mass ratio was added, and the scrap was removed after oxidation smelting at 1200℃ for 60min to obtain the copper liquid after impurity removal. After reduction and deoxidation, the copper content in the copper liquid was 99.91wt.%. The changes in the impurity element content of the scrap copper before and after impurity removal are shown in Table 6.

[0031]

Claims

1. A method for deep nickel removal from scrap copper, characterized in that: After the scrap copper is melted, an impurity remover A is first added for preliminary impurity removal, the slag is removed, and then dihydrogen phosphate is added for deep impurity removal to obtain a copper liquid with a nickel-iron content of less than 30 ppm; the impurity remover A comprises 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, and the non-iron component comprises SiO2 and Al2O3; the mass content of the iron-containing component in the impurity remover A is 10% to 96%; the single usage amount of the impurity remover A is 0.1% to 3% of the mass of the scrap copper, and the single usage amount of the dihydrogen phosphate is 0.1% to 2.5% of the mass of the scrap copper.

2. The method for deep nickel removal from scrap copper according to claim 1, characterized in that: After adding dihydrogen phosphate, the slag is removed after oxidative smelting for a period of time, and the iron content in the obtained copper liquid is less than 10ppm.

3. The method for deep nickel removal from scrap copper according to claim 1, characterized in that: The copper mass fraction in the scrap copper is greater than 96%.

4. The method for deep nickel removal from scrap copper according to claim 1, characterized in that: The iron-containing component may be one or more of hematite, limonite, magnetite, siderite, and pyrite.

5. The method for deep nickel removal from scrap copper according to claim 1, characterized in that: The non-ferrous components include gangue minerals containing SiO2 and Al2O3.

6. The method for deep nickel removal from scrap copper according to claim 1, characterized in that: The sum of the mass percentages of the iron-containing components and the non-iron components of SiO2 and Al2O3 in the impurity remover A is greater than 80%.

7. The method for deep nickel removal from scrap copper according to claim 1, characterized in that: The dihydrogen phosphate is selected from at least one of calcium dihydrogen phosphate, sodium dihydrogen phosphate and potassium dihydrogen phosphate.

8. The method for deep nickel removal from scrap copper according to claim 1, characterized in that: The single dosage of the impurity remover A is 0.5% to 2% of the mass of the scrap copper, and the number of uses is 1 to 3 times.

9. The method for deep nickel removal from scrap copper according to claim 1, characterized in that: The single dosage of the dihydrogen phosphate is 0.5% to 2% of the mass of the scrap copper, more preferably 1% to 2%, and the number of uses is 1 to 3 times.

10. The method for deep nickel removal from scrap copper according to claim 1, characterized in that: When the impurity remover A is used for preliminary impurity removal, the smelting temperature is 1150~1300℃, and the oxidation smelting time is 0.5~3h; when dihydrogen phosphate is added for deep impurity removal, the smelting temperature is 1150~1300℃, and the oxidation smelting time is 0.5~3h.

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