A method for graded extraction of copper anode slime from co-smelting

Abstract

This invention discloses a method for the tiered extraction of copper anode slime from co-smelting copper anodes, belonging to the fields of resource comprehensive utilization and non-ferrous metal metallurgy. The method is used to treat copper anode slime produced after co-smelting waste circuit board pyrolysis residue and copper sulfide ore, followed by blowing and electrolytic refining. The method includes: sulfidation leaching of the copper anode slime to preferentially allow tellurium to enter the leachate; reduction precipitation of the tellurium-containing leachate to recover tellurium products; atmospheric pressure mixed acid leaching of the sulfidation leaching residue to preferentially allow copper and selenium to enter the leachate, yielding a copper-selenium-containing leachate and a precious metal-enriched slag; chlorination leaching of the precious metal-enriched slag to allow gold to enter the chlorinated leachate and separate from silver; and SO2 reduction precipitation and extraction separation of the copper-selenium-containing leachate to sequentially recover selenium and copper. This method can achieve tiered separation and efficient recovery of Te, Se, Au, Ag, and Cu from novel copper anode slime produced by co-smelting, and has the advantages of a clear process, good selectivity, and suitability for closed-loop operation.

Description

Technical Field

[0001] This invention belongs to the field of comprehensive resource utilization and non-ferrous metal metallurgy technology, specifically relating to a method for the stepwise extraction of copper anode slime in synergistic smelting. Background Technology

[0002] Waste circuit boards contain copper, gold, silver, and various rare and dispersed elements, possessing high resource value. By employing thermal dehalogenation followed by co-smelting with copper sulfide ore, the valuable elements can be enriched through the trapping effect of copper matte on precious metals, and the adaptability of complex secondary resources to existing copper smelting processes can be improved. Existing co-smelting technology allows gold and silver to preferentially concentrate in the copper matte phase. After blowing and electrolytic refining, the copper matte phase forms anode mud, providing a carrier for subsequent rare and precious metal recovery.

[0003] However, compared to the anode slime formed under traditional primary copper smelting systems, the copper anode slime obtained from co-smelting systems has a more complex composition and a closer relationship between elements. It often exhibits characteristics of high silver and selenium content and low nickel and lead content, with a high degree of coupling in the distribution of elements such as Te, Se, Ag, Au, and Cu. In particular, the separation of selenium and tellurium is difficult, the copper-selenium system is intertwined with the precious metal system, and silver and gold have significant mutual influences, which brings difficulties to subsequent high-value recovery.

[0004] Existing research has shown that by co-smelting pyrolysis residue with copper sulfide ore and controlling oxygen-enriched side-blown smelting, precious metals can be enriched in copper matte and enter the subsequent refining system; however, for the specific copper anode mud formed by this co-smelting system, there is still a lack of stepwise extraction methods targeting its elemental occurrence characteristics. Summary of the Invention

[0005] To address these issues, this invention provides a method for the graded extraction of copper anode slime from synergistic smelting, which solves the above problems.

[0006] A method for graded extraction of copper anode slime from co-smelting processes, comprising:

[0007] S1. Sulfide leaching is performed on the copper anode mud to allow tellurium to preferentially enter the leaching solution, resulting in a tellurium-containing leaching solution and sulfide leaching residue.

[0008] S2. The tellurium-containing leachate is subjected to reduction precipitation to recover the tellurium product;

[0009] S3. The sulfide leaching residue is subjected to atmospheric pressure mixed acid leaching to allow copper and selenium to preferentially enter the leaching solution, resulting in copper-selenium leaching solution and precious metal enrichment residue.

[0010] S4. Chloride leaching is performed on the precious metal enrichment residue to allow gold to enter the chlorination leaching solution and separate from silver.

[0011] S5. The copper-selenium leaching solution is subjected to reduction precipitation and extraction separation to recover selenium and copper in sequence.

[0012] S6. The gold-containing, silver-containing, tellurium-containing, and selenium-containing products obtained in each step are further purified to obtain at least three products of gold, silver, tellurium, selenium, and copper.

[0013] Furthermore, the copper anode mud is a novel copper anode mud produced by co-smelting, characterized by high silver and selenium content and low nickel and lead content, and at least three of the elements Au, Ag, Se, Te and Cu are enriched in the copper anode mud.

[0014] Furthermore, in step S1, Na2S is used as the sulfidation leaching agent, wherein the Na2S concentration is 40–80 g / L, preferably 50–70 g / L; the leaching temperature is 70–95℃, preferably 85–90℃; the liquid-to-solid ratio is 5:1–10:1 mL / g, preferably 7:1–9:1 mL / g; and the leaching time is 0.5–2 h, preferably 0.8–1.2 h.

[0015] Furthermore, in step S1, the tellurium leaching rate is not less than 80%, preferably not less than 85%; and at least most of the copper, selenium, and precious metals are retained in the sulfide leaching residue to achieve preliminary separation of selenium and tellurium.

[0016] Furthermore, in step S2, Na2SO3 is used as a reducing agent for reduction precipitation, and the tellurium precipitation rate is not less than 95%, preferably not less than 98%, and the purity of the crude tellurium product is not less than 90 wt%, preferably not less than 95 wt%.

[0017] Furthermore, the atmospheric pressure mixed acid leaching in step S3 adopts an H2SO4-HNO3 mixed acid system and is carried out at atmospheric pressure, so that copper and selenium preferentially enter the leaching solution, while at least one of gold and silver is enriched in the leaching residue; wherein, the selenium leaching rate is not less than 80%, preferably not less than 90%.

[0018] Furthermore, in step S4, the chlorination leaching process allows gold to enter the chlorination leaching solution, while silver remains in the residue or is converted into a poorly soluble silver-containing phase, thereby achieving silver-gold separation.

[0019] Furthermore, in step S5, SO2 is first used to reduce and precipitate the copper-containing selenium leachate, so that selenium is preferentially precipitated, with a selenium precipitation rate of not less than 90%, preferably not less than 95%, and the purity of the obtained selenium product is not less than 90 wt%, preferably not less than 95 wt%; then the copper-containing solution after selenium removal is extracted and back-extracted, with a copper extraction rate of not less than 90%, preferably not less than 95%.

[0020] Furthermore, the method is carried out in the following order: tellurium separation by sulfidation, copper and selenium separation by atmospheric pressure mixed acid, gold separation by chloride, SO2 reduction, and copper separation by extraction. The copper back-extraction solution is returned to the copper electrolytic refining system for use, and silver is recovered by precipitation, with a silver precipitation rate of not less than 95%, preferably not less than 99%.

[0021] The method for graded extraction of copper anode slime from co-smelting in this application has the following specific advantages:

[0022] 1. By pre-sulfiding tellurium, the Se / Te coupling can be reduced, thereby improving the purity and process stability of subsequent selenium recovery.

[0023] 2. By combining atmospheric pressure mixed acid separation of copper selenium with chloride separation of gold, the copper selenium system and the precious metal system can be effectively decoupled.

[0024] 3. By reducing selenium with SO2 and extracting copper, the recovery efficiency of Se and Cu can be further improved, and the intermediate liquid can be reused in a closed loop. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 The flowchart illustrates a method for graded extraction of copper anode slime in a synergistic smelting process, as provided in an embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The copper anode slime processed in this invention differs from conventional anode slime from traditional primary copper smelting systems. It is anode slime enriched with Se / Te through co-smelting, exhibiting a more complex composition and higher enrichment of rare and precious metals. This type of anode slime typically exhibits high silver and selenium content and low nickel and lead content, with relatively high levels of Cu, Ag, Au, Se, and Te, making it suitable for refined recovery using a cascade extraction method.

[0029] Please see Figure 1 The diagram shows a flowchart of a method for the stepwise extraction of copper anode mud in a co-smelting process according to this application.

[0030] In the following embodiments, unless otherwise specified, the raw materials, equipment, reagents and testing methods used are all conventionally available in the art.

[0031] Example 1: Tellurium separation by sulfidation leaching.

[0032] The copper anode slime obtained from co-smelting followed by blowing and electrolytic refining is used as raw material. This anode slime contains elements such as Te, Se, Cu, Ag, Au, As, and Sb, among which Te is the priority target for separation in this step.

[0033] The copper anode mud was added to a leaching system using Na2S as the sulfidation leaching agent, and the leaching conditions were controlled as follows:

[0034] Na2S concentration: 40–80 g / L, preferably 50–70 g / L;

[0035] Leaching temperature: 70–95℃, preferably 85–90℃;

[0036] Liquid-to-solid ratio: 5:1 to 10:1 mL / g, preferably 7:1 to 9:1 mL / g;

[0037] Leaching time: 0.5–2 h, preferably 0.8–1.2 h.

[0038] Under the above conditions, Te in the anode mud preferentially enters the leachate, while Cu, Se and at least most of the precious metals remain in the leachate residue, thus achieving preliminary Se / Te separation.

[0039] In a preferred embodiment, the following specific conditions are adopted:

[0040] Na2S concentration: 60 g / L

[0041] Leaching temperature: 90℃

[0042] Liquid-to-solid ratio: 8:1 mL / g

[0043] Leaching time: 1 h

[0044] Under these preferred conditions, the following results were obtained:

[0045] The Te leaching rate was 88.16%;

[0046] The slag rate was 74.17%;

[0047] Approximately 94% of As enters the solution;

[0048] Approximately 75% of Sb enters the solution;

[0049] Cu, Se, and other precious metals are enriched by remaining in the alkaline leaching residue.

[0050] Therefore, the Te leaching rate in this step can reach no less than 80%, preferably no less than 85%.

[0051] Further research shows that the Te leaching process conforms to the Avrami kinetic model, with an apparent activation energy of 4.60 kJ / mol and an average n value of 0.0649, indicating that the process is mainly controlled by internal diffusion. In industrial applications, enhancement measures such as impregnation, ultrasonic or microwave assistance can be introduced as needed to improve leaching efficiency.

[0052] Example 2: Reduction precipitation to recover crude tellurium.

[0053] Take the tellurium-containing leachate obtained in Example 1, add Na2SO3 as a reducing agent to reduce and precipitate, so as to recover the tellurium product.

[0054] The tellurium precipitation rate can generally reach no less than 95%, preferably no less than 98%; the purity of the obtained crude tellurium product can generally reach no less than 90 wt%, preferably no less than 95 wt%.

[0055] In a preferred embodiment:

[0056] The precipitation rate of Te was 99.20%;

[0057] The purity of the crude tellurium product obtained was 96.50 wt%.

[0058] This embodiment demonstrates that the combined process of "Na2S sulfidation leaching + Na2SO3 reduction precipitation of tellurium" can achieve preferential enrichment and efficient recovery of Te.

[0059] Example 3: Copper-selenium separation by mixed acid under normal pressure.

[0060] The sulfide leaching residue obtained in Example 1 was used as raw material. The Te content in this leaching residue was significantly reduced, while elements such as Cu, Se, Ag, and Au were further enriched.

[0061] The sulfide leaching residue is added to an atmospheric pressure mixed acid leaching system for treatment. The mixed acid system is an H2SO4-HNO3 mixed acid system. Under atmospheric pressure conditions, by controlling the acidity, liquid-solid ratio, temperature, and leaching time, Cu and Se preferentially enter the liquid phase, while at least one of Au and Ag is enriched in the leaching residue, thereby obtaining a copper-selenium leaching solution and a precious metal-enriched residue.

[0062] In this step, the Se leaching rate can reach no less than 80%, preferably no less than 90%.

[0063] In a preferred embodiment:

[0064] The Se leaching rate was 90.10%.

[0065] At the same time, Cu and Se enter the leaching solution together, and the precious metals are further enriched in the leaching residue, achieving effective separation of the "copper-selenium system" and the "gold-silver system".

[0066] The results show that the mixed acid leaching process conforms to the contraction core model, with an apparent activation energy of 50.01 kJ / mol.

[0067] Example 4: Chlorination of precious metal enrichment slag.

[0068] The precious metal enrichment slag obtained in Example 3 was used as raw material. The enrichment slag has a high content of precious metals such as Au and Ag, and Cu, Se and Te have been partially or mostly removed in the previous steps.

[0069] The precious metal enrichment slag is placed in a chlorination leaching system for treatment, so that Au preferentially enters the chlorination leaching solution, while Ag is retained in the slag or transformed into a sparingly soluble silver-containing phase, thereby achieving further separation of Au and Ag.

[0070] In this step, the core control objective for chlorination leaching is:

[0071] Au enters the liquid phase;

[0072] Ag is retained in the solid phase or transformed into a sparingly soluble silver-containing phase;

[0073] This creates conditions for subsequent gold reduction, precipitation, electrowinning, or refining and recovery.

[0074] Example 5: SO2 reduction precipitation of selenium and extraction of copper.

[0075] The copper-selenium leaching solution obtained in Example 3 was used as the raw material. Cu and Se were the main elements to be recovered in this leaching solution.

[0076] First, SO2 is introduced into the copper-selenium leaching solution to preferentially reduce and precipitate the Se in the solution. After SO2 reduction, the Se precipitation rate can reach not less than 90%, preferably not less than 95%; the purity of the obtained selenium product can reach not less than 90 wt%, preferably not less than 95 wt%.

[0077] In a preferred embodiment:

[0078] The Se precipitation rate was 96.48%;

[0079] The purity of the obtained selenium product was 97.35%.

[0080] After selenium precipitation, the copper-containing solution after selenium removal is subjected to extraction and back-extraction. The copper extraction rate can reach no less than 90%, preferably no less than 95%.

[0081] In a preferred embodiment:

[0082] The Cu extraction rate was 96.46%.

[0083] The resulting copper-containing back-extraction solution can be returned to the copper electrolytic refining system for use.

[0084] Example 6: Overall tiered extraction process.

[0085] A novel copper anode slime, obtained through co-smelting followed by blowing and electrolytic refining, was used as raw material and subjected to overall stepwise extraction in the following order:

[0086] 1. Na2S sulfide leaching tellurium;

[0087] 2. Na₂SO₃ reduction to precipitate tellurium;

[0088] 3. Leaching of copper and selenium using a mixed acid solution of H2SO4 and HNO3 at atmospheric pressure;

[0089] 4. Chlorination leaching for gold separation;

[0090] 5. SO2 reduction and selenium precipitation;

[0091] 6. Extraction-back-extraction to recover copper;

[0092] 7. Silver precipitation recovery.

[0093] Under the preferred implementation conditions, the following results can be achieved:

[0094] Te leaching rate: 88.16%;

[0095] Te precipitation rate: 99.20%;

[0096] Crude tellurium purity: 96.50 wt%

[0097] Se leaching rate: 90.10%;

[0098] Se precipitation rate: 96.48%;

[0099] Selenium product purity: 97.35%;

[0100] Cu extraction rate: 96.46%;

[0101] Ag precipitation rate: 99.4%.

[0102] Meanwhile, the copper back-extraction solution can be returned to the copper electrolytic refining system for reuse, achieving closed-loop recycling.

[0103] This embodiment demonstrates that the "sulfidation tellurium separation—atmospheric pressure mixed acid copper and selenium separation—chlorination gold separation—SO2 reduction—extraction copper separation" route established by the present invention can adapt to the characteristics of complex composition and complex element coexistence relationships in the co-smelting of novel copper anode mud, and achieve orderly separation and efficient recovery of elements such as Te, Se, Cu, Ag and Au.

[0104] Comparative Example 1: Pre-sulfurization and tellurium separation were performed.

[0105] The same copper anode mud raw material as in Example 6 was used, but the Na2S sulfidation leaching step was omitted, and mixed acid leaching and subsequent treatment were carried out directly.

[0106] The results show that Te and Se significantly interfere with each other in subsequent processes, leading to a decrease in selenium product purity, a more complex liquid phase system, and increased difficulty in process control. This indicates that setting a pre-sulfurization tellurium separation step is beneficial for reducing Se / Te coupling and improving the stability of subsequent separation.

[0107] Comparative Example 2: Selenium precipitation without prior SO2 precipitation

[0108] The same preliminary process as in Example 6 was used, but instead of SO2 reduction, copper extraction was performed directly on the copper-containing selenium leachate.

[0109] The results showed that the subsequent copper extraction process was significantly disrupted due to the ineffective pre-removal of Se, leading to a decrease in copper recovery stability and product quality. This demonstrates the rationality of adopting the sequence of "selenium precipitation first, then copper extraction".

[0110] Comparative Example 3: The copper back-extraction solution is not reused in the electrolysis system.

[0111] The same separation process as in Example 6 was used, but the copper back-extraction liquid was treated as waste liquid and not returned to the copper electrolytic refining system.

[0112] The results show that this method increases the consumption of fresh acid and the burden of solution processing, which is detrimental to the overall economic efficiency and closed-loop operation of the process. This indicates that returning the copper back-extraction solution to the copper electrolytic refining system has significant industrial adaptability advantages.

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for the stepwise extraction of copper anode slime from synergistic smelting, characterized in that, include: S1. Sulfide leaching is performed on the copper anode mud to allow tellurium to preferentially enter the leaching solution, resulting in a tellurium-containing leaching solution and sulfide leaching residue. S2. The tellurium-containing leachate is subjected to reduction precipitation to recover the tellurium product; S3. The sulfide leaching residue is subjected to atmospheric pressure mixed acid leaching to allow copper and selenium to preferentially enter the leaching solution, resulting in copper-selenium leaching solution and precious metal enrichment residue. S4. Chloride leaching is performed on the precious metal enrichment residue to allow gold to enter the chlorination leaching solution and separate from silver. S5. The copper-selenium leaching solution is subjected to reduction precipitation and extraction separation to recover selenium and copper in sequence. S6. The gold-containing, silver-containing, tellurium-containing, and selenium-containing products obtained in each step are further purified to obtain at least three products of gold, silver, tellurium, selenium, and copper.

2. The method for graded extraction of copper anode slime from co-smelting according to claim 1, characterized in that, The copper anode mud is a novel copper anode mud produced by co-smelting, characterized by high silver and selenium content and low nickel and lead content, and at least three of the elements Au, Ag, Se, Te and Cu are enriched in the copper anode mud.

3. The method for graded extraction of copper anode slime from co-smelting according to claim 1, characterized in that, In step S1, Na2S is used as the sulfidation leaching agent, and the Na2S concentration is 40-80 g / L, preferably 50-70 g / L; the leaching temperature is 70-95℃, preferably 85-90℃; the liquid-solid ratio is 5:1-10:1 mL / g, preferably 7:1-9:1 mL / g; and the leaching time is 0.5-2 h, preferably 0.8-1.2 h.

4. The method for graded extraction of copper anode slime from co-smelting according to claim 3, characterized in that, In step S1, the tellurium leaching rate is not less than 80%, preferably not less than 85%; and at least most of the copper, selenium and precious metals are retained in the sulfide leaching residue to achieve preliminary separation of selenium and tellurium.

5. The method for graded extraction of copper anode slime from co-smelting according to claim 1, characterized in that, In step S2, Na2SO3 is used as a reducing agent for reduction precipitation. The tellurium precipitation rate is not less than 95%, preferably not less than 98%, and the purity of the crude tellurium product is not less than 90 wt%, preferably not less than 95 wt%.

6. The method for graded extraction of copper anode slime from co-smelting according to claim 1, characterized in that, The atmospheric pressure mixed acid leaching in step S3 adopts an H2SO4-HNO3 mixed acid system and is carried out at atmospheric pressure, so that copper and selenium preferentially enter the leaching solution, while at least one of gold and silver is enriched in the leaching residue; wherein, the selenium leaching rate is not less than 80%, preferably not less than 90%.

7. The method for graded extraction of copper anode slime from co-smelting according to claim 1, characterized in that, In step S4, the chlorination leaching process allows gold to enter the chlorination leaching solution, while silver remains in the residue or is converted into a poorly soluble silver-containing phase, thereby achieving silver-gold separation.

8. The method for graded extraction of copper anode slime from co-smelting according to claim 1, characterized in that, In step S5, SO2 is first used to reduce and precipitate the copper-containing selenium leachate, so that selenium is preferentially precipitated, with a selenium precipitation rate of not less than 90%, preferably not less than 95%, and the purity of the obtained selenium product is not less than 90 wt%, preferably not less than 95 wt%. Then, the copper-containing solution after selenium removal is extracted and back-extracted, with a copper extraction rate of not less than 90%, preferably not less than 95%.

9. The method for graded extraction of copper anode slime from co-smelting according to claim 1, characterized in that, The method is carried out in the following order: tellurium separation by sulfidation, copper and selenium separation by atmospheric mixed acid, gold separation by chlorination, SO2 reduction, and copper separation by extraction. The copper back-extraction solution is returned to the copper electrolytic refining system for use. Silver is recovered by precipitation, with a silver precipitation rate of not less than 95%, preferably not less than 99%.

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