Method for recovering copper oxide from low-grade copper sludge

Abstract

The invention discloses a method for recovering copper oxide from low-grade copper sludge, which comprises the following steps: providing leaching ammonia water, low-grade copper sludge and an oxidizing agent, mixing to obtain a first mixed system, and separating to obtain primary filter residue and primary filtrate after leaching; and mixing the primary filtrate with an alkali source to obtain a second mixed system, heating, and separating to obtain a copper oxide crude product and a secondary filtrate. According to the method provided by the invention, resource recycling of a large amount of low-grade copper sludge is facilitated, good resource recycling is realized, and the recycling cost is further reduced.

Description

Technical Field

[0001] This application relates to the field of solid waste resource utilization, and in particular to a method for recovering copper oxide from low-grade copper sludge. Background Technology

[0002] With the rapid increase in demand for metal mineral resources, high-grade primary metal mineral resources are becoming increasingly depleted. On the one hand, the processes of metal resource mining, beneficiation, smelting, and product utilization generate a large amount of complex and diverse metal waste, which can easily cause serious environmental pollution if not handled properly. On the other hand, metal waste from the electronics manufacturing industry is often rich in various valuable metals such as gold, silver, nickel, and copper, making it a valuable secondary metal resource.

[0003] Low-grade copper sludge (copper content ≤2%), as a secondary resource, is often disposed of by direct landfill due to its high difficulty and cost in recycling, which undoubtedly causes environmental pollution and resource waste. Currently, the main methods for treating secondary metal resources are pyrometallurgical and hydrometallurgical processes. Traditional pyrometallurgical processes mainly obtain metal through converter smelting, which suffers from high energy consumption, low metal recovery rates, and secondary pollution. Conventional oxidative acid leaching or chlorination leaching methods easily cause the leaching of impurity elements (such as iron), which is not only costly but also seriously affects the purity of subsequent copper and other products.

[0004] Therefore, how to achieve low-cost recovery of copper resources from low-grade copper-containing sludge, improve the overall metal recovery rate, and realize the full-component resource recovery and harmless disposal of low-grade multi-metal complex materials are urgent technical problems to be solved. Summary of the Invention

[0005] In view of this, this application provides a method for recovering copper oxide from low-grade copper sludge.

[0006] The embodiments of this application are implemented as follows: A method for recovering copper oxide from low-grade copper sludge includes the following steps: Ammonia water for leaching, low-grade copper mud and oxidant are provided and mixed to obtain a first mixed system. After leaching, primary filter residue and primary filtrate are separated. The primary filtrate is mixed with an alkali source to obtain a second mixed system, which is then separated after heating to obtain crude copper oxide and a secondary filtrate.

[0007] The method provided in this application is beneficial for the resource recovery of large volumes of low-grade copper sludge. The recovered copper oxide can have a copper content of over 40%, and the ammonia recovery efficiency can reach over 90%, achieving good resource recycling and further reducing recycling costs. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 This is a process flow diagram of a method for recovering copper oxide from low-grade copper sludge provided in an embodiment of this application. Detailed Implementation

[0010] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application.

[0011] In this application, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in its actual use or operating state, specifically the orientation shown in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative purposes and do not impose numerical requirements or establish a numerical order.

[0012] In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0013] In this application, "at least one" means one or more, and "more than one" means two or more. "One or more", "at least one of the following", or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0014] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0015] The technical solution of this application is as follows: Please see Figure 1 This application provides a method for recovering copper oxide from low-grade copper sludge, comprising the following steps: Ammonia water for leaching, low-grade copper mud and oxidant are provided and mixed to obtain a first mixed system. After leaching, primary filter residue and primary filtrate are separated. The primary filtrate is mixed with an alkali source to obtain a second mixed system, which is then separated after heating to obtain crude copper oxide and a secondary filtrate.

[0016] In some embodiments, providing the extracted ammonia water includes: providing ammonia water raw material and water, mixing them to obtain the extracted ammonia water; the ammonia water raw material is concentrated ammonia water, and the mass fraction of the concentrated ammonia water is 25wt%~30wt%. Specifically, the mass fraction of the concentrated ammonia water can be 25wt%, 26wt%, 27wt%, 28wt%, 29wt%, 30wt%, or a range between any two points.

[0017] In some embodiments, after obtaining the first filter residue, the process further includes washing the first filter residue.

[0018] In some embodiments, the secondary filtrate is used to wash the primary filter residue, and the washing liquid after washing is mixed with the ammonia raw material and water; and / or, the secondary filtrate is mixed with the ammonia raw material and water. Through filtrate reuse technology, wastewater treatment costs can be significantly reduced and ammonia recovery can be achieved at a high efficiency of over 90%.

[0019] To reduce salt content in the system and avoid affecting the extraction effect, in some embodiments, the secondary filtrate is allowed to flow in an open stream, allowing a portion of the secondary filtrate to wash the primary filter residue; the open stream ratio is 5% to 20%. Specifically, the open stream ratio can be 5%, 10%, 15%, 20%, or any range between two points; the open stream secondary filtrate enters the wastewater deep treatment process.

[0020] Specifically, the method for recovering copper oxide from low-grade copper sludge may include the following steps: S1 Preparation of Ammonia Extraction Solution: Prepare ammonia extraction solution using concentrated ammonia solution (25%) and tap water; S2 Oxidized Ammonia Leaching: Low-grade copper mud and oxidant are added, and the leaching ammonia water is added to the low-grade copper mud for soaking to obtain a first mixed system. The mixture is stirred and leached. S3 First-stage pressure filtration: The first mixed system after the extraction in step S2 is subjected to pressure filtration to separate the first-stage filter residue and the first-stage filtrate. S4 Ammonia Stripping: Add an alkali source to the first filtrate from S3 above to adjust it to a strongly alkaline environment to obtain a second mixed system. Heat the mixture and react until all copper salts are converted into copper oxide. S5 Secondary pressure filtration: The second mixed system after heat treatment is subjected to thermal filtration to obtain crude copper oxide and secondary filtrate; S6 Washing: The secondary filtrate produced in step S5 above is used to wash the primary filter residue. The washing solution is returned to prepare the ammonia extraction solution, and the filter residue is outsourced for processing.

[0021] It is understandable that copper mud and ammonia have multiple coordination forms. The following are the stability constants of the copper ammonia complex ion at 25℃. According to the stability constants, the copper ammonia complex ion should be Cu(NH3)4. 2+ and Cu(NH3)5 2+ Mostly.

[0022]

[0023] The reaction equation for the extraction of copper mud with ammonia is: Cu 2+ +nNH3·H2O→Cu(NH3)n 2+ +nH2O The chemical equation for the ammonia stripping reaction is: Cu(NH3)n 2+ +2NaOH=CuO+nNH3+2Na + +H2O In some embodiments, the mass fraction of the extracted ammonia solution is 8 wt% to 15 wt%. Specifically, the mass fraction of the extracted ammonia solution can be 8 wt%, 10 wt%, 12 wt%, 15 wt%, or a range between any two points; the concentration of the ammonia solution can be rapidly determined by spectrophotometry.

[0024] In some embodiments, the extraction time is 4 to 6 hours. Specifically, the extraction time can be 4 hours, 5 hours, 5.5 hours, 6 hours, or any range between two points.

[0025] In some embodiments, the alkali source is caustic soda (sodium hydroxide), and the pH of the second mixture is greater than or equal to 12.

[0026] In some embodiments, the heat treatment temperature is 80°C to 100°C, and the heat treatment time is 0.2h to 1h. Specifically, the heat treatment temperature can be 80°C, 85°C, 90°C, 95°C, 100°C, or a range between any two points; the heat treatment time can be 0.2h, 0.5h, 0.8h, 1h, or a range between any two points.

[0027] In some embodiments, the heating process further includes collecting the volatilized ammonia gas, which is then condensed and mixed with the ammonia water raw material and water.

[0028] During the heating process, the reaction time is 15-20 minutes to achieve complete precipitation of copper oxide. A small amount of ammonia is distilled off and recovered by condensation, while a large amount of ammonia remains in the solution and can be directly reused. At this time, the pH of the second mixed system is between 11.4 and 11.6. Continuing to heat the system can ensure a complete reaction and allow the ammonia to be distilled off. The volatilized ammonia is then recovered by condensation for use in the preparation of the ammonia extraction solution in step S1.

[0029] In some embodiments, the solid-liquid mass ratio of the low-grade copper sludge to the ammonia extraction solution is 1:(4~10), preferably 1:(4~6). Specifically, the solid-liquid mass ratio of the low-grade copper sludge to the ammonia extraction solution can be 1:4, 1:5, 1:6, 1:8, 1:10, or any range between these two points.

[0030] In some embodiments, the extraction temperature is 40°C to 50°C. Specifically, the extraction temperature can be 40°C, 45°C, 50°C, or a range between any two points.

[0031] In some embodiments, the oxidant includes one or more of sodium hypochlorite, hydrogen peroxide, and sodium persulfate. The addition of the oxidant can oxidize the low-valent copper ions in the complex copper sludge to divalent copper ions.

[0032] In some embodiments, the mass ratio of the oxidant to the low-grade copper sludge is (1~5):100. Specifically, the mass ratio of the oxidant to the low-grade copper sludge can be 1:100, 2:100, 3:100, 4:100, 5:100, or any range between these two points.

[0033] The method for recovering copper oxide from low-grade copper sludge provided in this application has the following advantages compared with the prior art: (1) Copper is selectively extracted from low-grade metal sludge by ammonia water with an extraction efficiency of over 80%. At the same time, the ammonia in the system is recycled through process design, which greatly saves the energy consumption of the system, realizes ammonia circulation, and achieves an ammonia recovery efficiency of over 90%. (2) The crude copper oxide recovered by the ammonia stripping treatment technology has high purity, reaching more than 40% on a wet basis, and has a high sales coefficient; (3) The copper oxide recovery technology in copper mud of the present invention has a lower cost than traditional processes through the integrated operation of "leaching-ammonia stripping-reuse", which can be operated continuously and is suitable for industrial production.

[0034] The present application will be specifically described below through specific embodiments. The following embodiments are only some embodiments of the present application and are not intended to limit the present application.

[0035] Example 1 This embodiment is a laboratory example. It uses sludge from the bottom of an electroplating plant, which is dark green in color and has the following composition:

[0036] Analysis showed that the dry basis copper content was 3.2%, which yielded a wet basis copper content of 1.216%.

[0037] The following steps were followed to conduct a small-scale resource recovery experiment of low-grade copper mud in the laboratory: Leaching test: S1 Preparation of ammonia extraction solution: Prepare ammonia solution for extraction using concentrated ammonia solution (25%) and tap water, wherein the concentration of the ammonia extraction solution is 8%; S2 Ammonia Oxidation Immersion: Take 500g of low-grade copper mud into a beaker, add 10g of hydrogen peroxide (30%), add 2000g of the leaching ammonia water described in S1 to the low-grade copper mud for immersion, and stir at 40℃ for 4h. S3 First-stage pressure filtration: The mixture after the extraction in step S2 is separated by pressure filtration to obtain 490g of primary filter residue and 2450g of primary filtrate; S4 Ammonia Stripping: Add caustic soda to the first filtrate from S3 above to adjust the pH to 12, heat to 80~100℃, and react for 15 minutes until all copper salts are converted into copper oxide. S5 Secondary pressure filtration: The copper oxide mixed solution in S4 above is subjected to hot filtration to obtain crude copper oxide (wet weight 10.8g) and secondary filtrate; S6 Washing: The secondary filtrate produced in step S5 above is used to wash the primary filter residue. The washing solution is returned to prepare ammonia water, and the filter residue is outsourced for processing.

[0038] Small-scale test of filtrate reuse: To prepare the ammonia extraction solution, the filter residue washing liquid, secondary filtrate, and condensed ammonia solution were used. The flow rate of the secondary filtrate was 5%, and the mass of the prepared ammonia extraction solution was 1949g. The ammonia nitrogen concentration was tested and found to be only 7.5%. 56g of ammonia solution (25%) was added, and the ammonia concentration was then 8%.

[0039] The remaining steps are carried out according to steps S1 to S6, and samples are sent for testing.

[0040] Table 1 shows the data detection and analysis of the embodiments of the present invention: Table 1

[0041] The test results of Example 1 show that the low-grade copper sludge in this example achieved relatively ideal results through the "leaching-ammonia stripping-reuse" process. The test data indicates that the copper recovery rate in the sludge can reach over 80%, the grade of the obtained copper oxide can reach over 45%, and the ammonia recovery rate in the ammonia stripping process can reach over 90%. In summary, this invention achieves good resource recycling and provides a low-cost process for the resource utilization of low-grade copper sludge, suitable for industrial-scale production.

[0042] The technical solutions provided by the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A process for the recovery of copper oxides from low grade copper slimes characterised in that, Includes the following steps: Ammonia water for leaching, low-grade copper mud and oxidant are provided and mixed to obtain a first mixed system. After leaching, primary filter residue and primary filtrate are separated. The primary filtrate is mixed with an alkali source to obtain a second mixed system, which is then separated after heating to obtain crude copper oxide and a secondary filtrate.

2. The method for recovering copper oxide from low-grade copper sludge according to claim 1, characterized in that, The mass fraction of the extracted ammonia solution is 8wt%~15wt%; The extraction time is 4-6 hours.

3. The method for recovering copper oxide from low-grade copper sludge according to claim 1, characterized in that, The alkali source is sodium hydroxide, and the pH of the second mixed system is greater than or equal to 12.

4. The method for recovering copper oxide from low-grade copper sludge according to claim 1, characterized in that, The temperature of the heat treatment is 80℃~100℃, and the time of the heat treatment is 0.2h~1h.

5. A method for recovering copper oxide from low-grade copper sludge according to claim 1, characterized in that, The solid-liquid mass ratio of the low-grade copper mud and the leaching ammonia water is 1:(4~10), preferably, the solid-liquid mass ratio of the low-grade copper mud and the leaching ammonia water is 1:(4~6). The extraction temperature is 40℃~50℃.

6. The method for recovering copper oxide from low-grade copper sludge according to claim 1, characterized in that, Oxidizing agents include one or more of sodium hypochlorite, hydrogen peroxide, and sodium persulfate.

7. A method for recovering copper oxide from low-grade copper sludge according to claim 1, characterized in that, The mass ratio of the oxidant to the low-grade copper mud is (1~5):

100.

8. A method for recovering copper oxide from low-grade copper sludge according to claim 1, characterized in that, The provision of the extracted ammonia water includes: providing ammonia water raw material and water, and mixing them to obtain the extracted ammonia water; The ammonia water raw material is concentrated ammonia water, and the mass fraction of the concentrated ammonia water is 25wt%~30wt%.

9. A method for recovering copper oxide from low-grade copper sludge according to claim 8, characterized in that, The heat treatment also includes collecting the volatilized ammonia gas, which is then condensed and mixed with the ammonia water raw material and water; and / or After obtaining the first filter residue, the process also includes washing the first filter residue; The secondary filtrate is used to wash the primary filter residue, and the washing solution after washing is mixed with the ammonia raw material and water; and / or The secondary filtrate is mixed with the ammonia water raw material and water.

10. A method for recovering copper oxide from low-grade copper sludge according to claim 8, characterized in that, The secondary filtrate is allowed to flow in an open stream, allowing a portion of the secondary filtrate to wash the primary filter residue. The open flow ratio is 5% to 20%.

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