A method for preparing high-quality hollow spheres using copper smelting waste slag

Abstract

The present invention provides a method for preparing high-quality hollow spheres by using copper smelting waste slag, which relates to the technical field of secondary resource recycling in the non-ferrous metallurgy industry. The preparation method of the high-quality hollow spheres is as follows: taking copper smelting waste slag as the basic raw material, adding an appropriate amount of S, mixing to form a mixture, and using a ball mill to grind the mixture to obtain powder; making the powder into hollow spheres through a plasma spray gun; using an air sieve to screen the hollow spheres; under the protection of an inert gas, performing high-temperature roasting on the screened hollow spheres to reduce the content of toxic elements in the hollow spheres, that is, obtaining high-quality hollow spheres that meet national standards and can be industrially applied. The overall preparation process of the present invention is simple, can greatly reduce the content of the toxic element As in the hollow spheres, and enables the prepared hollow spheres to become products that can be directly industrially applied.

Description

Technical Field

[0001] The present invention relates to the field of secondary resource recycling in the non-ferrous metallurgy industry, and specifically to a method for preparing high-quality hollow spheres using copper smelting slag. Background Art

[0002] At present, most copper smelting enterprises use pyrometallurgical processes to produce copper. This process generates a large amount of copper smelting slag. The accumulation of a large amount of copper smelting slag not only occupies land resources but also pollutes soil and water resources. Copper smelting slag is rich in various valuable metal elements such as Cu, Fe, Zn, Pb, and Ni. Currently, the utilization rate of Cu in copper smelting slag is less than 12%, and the utilization rate of Fe is less than 1%. Developing technologies for recycling copper smelting slag can bring significant economic benefits, save the cost of importing mineral resources, and relieve environmental pressure. Therefore, research on the resource utilization of copper smelting slag is urgent.

[0003] Hollow spheres have the advantages of a large specific surface area, low density, easy dispersion, and controllable morphology, and are widely used in fields such as sewage purification, chemical catalysts, catalyst carriers, nano-reactors, and drug sustained release. If hollow spheres can be prepared using copper smelting slag, its recycling rate can be significantly improved. Patent CN110204352A provides a method for preparing magnetic hollow ceramic microspheres from copper slag tailings. It uses a flame spray gun to melt-spray copper slag tailings mixed with various auxiliary materials (such as lime and magnesium oxide powder) to form hollow spheres. However, this preparation method has the following two deficiencies:

[0004] (1) The powder forming by flame spray gun melting is highly dependent on the temperature of the flame and the added auxiliary materials used to lower the melting point of the slag tailings. Maintaining a high temperature is the key factor for powder forming. However, the temperature limit of the flame spray gun is about 3000 °C. The upper limit of the flame temperature and the addition of auxiliary materials limit the composition and forming control measures of the hollow spheres.

[0005] (2) It is difficult to significantly remove the toxic element As during the forming process of the hollow spheres. A large amount of economic and technical investment is required for the subsequent application of the powder to eliminate the influence of the toxic element As. Summary of the Invention

[0006] In order to solve the deficiencies in the prior art, the present invention provides a method for preparing high-quality hollow spheres using copper smelting slag. The preparation process is simple, can significantly reduce the content of the toxic element As in the hollow spheres, and enables the prepared hollow spheres to become products that meet national standards and can be directly applied industrially.

[0007] To achieve the above objective, the specific solution adopted by the present invention is as follows:

[0008] A method for preparing high-quality hollow spheres from copper smelting waste slag mainly includes the following steps:

[0009] Step 1: Using copper smelting waste slag as the basic raw material, adding an appropriate amount of S, mixing to form a mixture, and using a ball mill to grind the mixture to obtain powder;

[0010] Step 2: Making the powder into hollow spheres through a plasma spray gun;

[0011] Step 3: Using an air sieve to screen the hollow spheres;

[0012] Step 4: Under the protection of inert gas, performing high-temperature roasting on the screened hollow spheres to reduce the content of toxic element As in the hollow spheres.

[0013] Further, by mass percentage, the copper smelting waste slag includes the following components: Fe 2 O 3 54%, SiO 2 29%, CaO 3%, Al 2 O 3 3%, ZnO ≤ 3%, Na 4 SiO 4 ≤ 2%, MgO ≤ 1.5%.

[0014] Further, in Step 1, the addition amount of S is 1 - 5% of the amount of copper smelting waste slag.

[0015] Further, in Step 1, the particle size of the obtained powder is 20 - 100 μm.

[0016] Further, in Step 2, the specific parameters for preparing hollow spheres are: using argon and hydrogen as working gases, the argon pressure is 5 - 20 MPa, the argon flow rate is 60 - 120 L / min, the hydrogen pressure is 10 - 15 MPa, the hydrogen flow rate is 10 - 20 L / min; the current is 280 - 680 A; the voltage is 90 - 160 V; the powder feeding rate is 1 - 10 kg / min; the plasma spraying temperature is 8000 - 10000 °C.

[0017] Further, in Step 2, collecting the hollow spheres with liquid nitrogen, the collection distance is 100 - 500 mm; the tail gas generated during the preparation process is filtered through a bag filter.

[0018] Further, the particle size of the hollow spheres obtained by screening in Step 3 is 20 - 60 μm, and the wall thickness is 0.2 - 3 μm.

[0019] Further, in Step 4, under the protection of argon gas, the hollow spheres are calcined at a temperature of 600 - 750 °C for 2 - 10 h, and the tail gas generated during the high-temperature calcination process is filtered through a bag filter.

[0020] Beneficial effects:

[0021] 1) The present invention converts copper smelting waste slag into high-quality hollow sphere products that can be directly applied industrially, enabling the comprehensive utilization of solid waste resources and creating new economic value; 2) The present invention prepares hollow spheres through a plasma spray gun, and the plasma spray gun can generate a higher temperature, enabling the substances in the powder to be quickly melted into spheres; 3) The rapid and efficient heating of the plasma enables the powder to generate a higher vapor pressure after melting, and the higher vapor pressure causes the molten powder to form hollow spheres during flight; 4) The added S can react with As to form AsS, and under high-temperature conditions, AsS can quickly volatilize to achieve the purpose of removing As. The appropriate amount of S combined with a higher plasma temperature can enable the toxic element As in the powder to quickly volatilize and be removed. Combined with high-temperature calcination, the content of the toxic element As in the hollow spheres can be significantly reduced, making the hollow spheres products that can be directly applied industrially; 5) The present invention realizes the secondary resource reuse of copper smelting waste slag, and the process is simple and easy to scale up for production and application. Description of the drawings

[0022] Figure 1 It is the SEM diagram of the product prepared in Example 1 of the present invention. Detailed implementation manners

[0023] The present invention provides a method for preparing high-quality hollow spheres using copper smelting waste slag, and its steps are as follows:

[0024] Step 1: Using copper smelting waste slag as the basic raw material, adding 1 - 5% of S based on the content of copper smelting waste slag, mixing to form a mixture, and using a ball mill to grind the mixture to obtain a powder with a particle size of 20 - 100 μm;

[0025] Step 2: Making the powder into hollow spheres through a plasma spray gun, collecting the hollow spheres with liquid nitrogen, and filtering the tail gas generated during the preparation process of the hollow spheres through a bag filter;

[0026] Step 3: Screening the collected hollow spheres through an air sieve, and collecting the hollow spheres with a particle size of 20 - 60 μm and a wall thickness of 0.2 - 3 μm;

[0027] Step 4: Subject the collected hollow spheres to high-temperature roasting under the protection of an inert gas (such as argon) at a temperature of 600 - 750 °C for 2 - 10 h to further remove the toxic element As in the hollow spheres, thus obtaining high-quality hollow spheres. The tail gas generated during the high-temperature roasting process is filtered through a bag filter;

[0028] Step 5: Return the recovered As-containing substances to the white arsenic smelting process.

[0029] Among them, in Step 1, the copper smelting waste slag is obtained by ball milling and crushing large particles of the slag after copper smelting. By mass percentage, the copper smelting waste slag includes the following components: Fe 2 O 3 54%, SiO 2 29%, CaO 3%, Al 2 O 3 3%, ZnO ≤ 3%, Na 4 SiO 4 ≤ 2%, MgO ≤ 1.5%.

[0030] Among them, in Step 2, the specific parameters for preparing the hollow spheres are as follows: Using argon and hydrogen as working gases, the argon pressure is 5 - 20 MPa, the argon flow rate is 60 - 120 L / min, the hydrogen pressure is 10 - 15 MPa, and the hydrogen flow rate is 10 - 20 L / min; the current is 280 - 680 A; the voltage is 90 - 160 V; the powder feeding rate is 1 - 10 kg / min; the plasma spray melting temperature is 8000 - 10000 °C, collecting the hollow spheres with liquid nitrogen, and the hollow sphere collection distance is 100 - 500 mm; filtering the tail gas generated during the preparation process with a bag filter.

[0031] Example 1

[0032] This example provides a method for preparing high-quality hollow spheres using copper smelting waste slag, and its steps are as follows:

[0033] Step 1: Using copper smelting waste slag as the basic raw material, adding 1% of S based on the content of the copper smelting waste slag, mixing to form a mixture, and using a ball mill to grind the mixture to obtain a powder with a particle size of 20 μm;

[0034] Step 2: Prepare hollow spheres through a plasma spray gun. Among them, the argon pressure is 5 MPa, the argon flow rate is 60 L / min; the hydrogen pressure is 10 MPa, the hydrogen flow rate is 10 L / min; the current is 280 A; the voltage is 90 V; the powder feeding rate is 1 kg / min; the plasma spray melting temperature is 8000 °C, collecting the hollow spheres with liquid nitrogen, and the hollow sphere collection distance is 100 mm; filtering the tail gas generated during the preparation process with a bag filter;

[0035] Step 3: Screen the collected hollow spheres through an air classifier;

[0036] Step 4: Subject the screened hollow spheres with a particle size of 20 μm and a wall thickness of 0.2 - 1 μm to high-temperature roasting under argon protection at a temperature of 600 °C for 2 h to further remove the toxic element As in the hollow spheres, thus obtaining high-quality hollow spheres. The tail gas generated during the roasting process is filtered through a bag filter;

[0037] Step 5: Return the recovered As-containing substances to the white arsenic smelting process.

[0038] The SEM image of the product prepared in this example is as Figure 1 shown. It can be seen from Figure 1 that hollow spherical powders are indeed generated.

[0039] Example 2

[0040] This example provides a method for preparing high-quality hollow spheres using copper smelting waste slag, and the steps are as follows:

[0041] Step 1: Using copper smelting waste slag as the basic raw material, add 2% of S based on the content of copper smelting waste slag, mix to form a mixture, and grind the mixture using a ball mill to obtain a powder with a particle size of 40 μm;

[0042] Step 2: Prepare hollow spheres through a plasma spray gun with an argon pressure of 10 MPa, an argon flow rate of 80 L / min; a hydrogen pressure of 12 MPa, a hydrogen flow rate of 12 L / min; a current of 360 A; a voltage of 120 V; a powder feeding rate of 4 kg / min; a plasma spray melting temperature of 8500 °C; collect the hollow spheres using liquid nitrogen with a hollow sphere collection distance of 200 mm; filter the tail gas generated during the preparation process using a bag filter;

[0043] Step 3: Screen the collected hollow spheres through an air classifier;

[0044] Step 4: Subject the screened hollow spheres with a particle size of 30 μm and a wall thickness of 1 - 2 μm to high-temperature roasting under argon protection at a temperature of 650 °C for 4 h to further remove the toxic element As in the hollow spheres, thus obtaining high-quality hollow spheres. The tail gas generated during the roasting process is filtered through a bag filter;

[0045] Step 5: Return the recovered As-containing substances to the white arsenic smelting process.

[0046] Example 3

[0047] This example provides a method for preparing high-quality hollow spheres using copper smelting waste slag, and the steps are as follows:

[0048] Step 1: Using copper smelting slag as the basic raw material, add S accounting for 4% of the copper smelting slag content, mix to make a mixture, and use a ball mill to grind the mixture to obtain a powder with a particle size of 80 μm;

[0049] Step 2: Prepare hollow spheres through a plasma spray gun. The argon pressure is 16 MPa, the argon flow rate is 100 L / min; the hydrogen pressure is 13 MPa, the flow rate is 16 L / min; the current is 480 A; the voltage is 140 V; the powder feeding rate is 8 kg / min; the plasma spraying temperature is 9200 °C. Collect the hollow spheres with liquid nitrogen, and the hollow sphere collection distance is 400 mm; filter the tail gas generated during the preparation process with a bag filter;

[0050] Step 3: Screen the collected hollow spheres through an air sieve;

[0051] Step 4: Roast the screened hollow spheres with a particle size of 50 μm and a wall thickness of 2 - 2.5 μm under argon protection at a temperature of 700 °C for 8 h to further remove the toxic element As in the hollow spheres, that is, obtain high-quality hollow spheres. Filter the tail gas generated during the roasting process with a bag filter;

[0052] Step 5: Return the recovered As-containing substances to the white arsenic smelting process.

[0053] Example 4

[0054] This example provides a method for preparing high-quality hollow spheres using copper smelting slag, and its steps are as follows:

[0055] Step 1: Using copper smelting slag as the basic raw material, add S accounting for 5% of the copper smelting slag content, mix to make a mixture, and use a ball mill to grind the mixture to obtain a powder with a particle size of 100 μm;

[0056] Step 2: Prepare hollow spheres through a plasma spray gun. The argon pressure is 20 MPa, the argon flow rate is 120 L / min; the hydrogen pressure is 15 MPa, the hydrogen flow rate is 20 L / min; the current is 680 A; the voltage is 160 V; the powder feeding rate is 10 kg / min; the plasma spraying temperature is 10000 °C. Collect the hollow spheres with liquid nitrogen, and the hollow sphere collection distance is 500 mm; filter the tail gas generated during the preparation process with a bag filter;

[0057] Step 3: Screen the collected hollow spheres through an air sieve;

[0058] Step 4: The hollow spheres with a particle size of 60 μm and a wall thickness of 2 - 3 μm obtained by screening are subjected to high-temperature calcination under argon protection at a temperature of 750 °C for 10 h to further remove the toxic element As in the hollow spheres, thereby obtaining high-quality hollow spheres. The tail gas generated during the calcination process is filtered through a bag filter;

[0059] Step 5: Return the recovered As-containing substances to the white arsenic smelting process.

[0060] Comparative Example 1

[0061] The difference between Comparative Example 1 and Example 1 is that it does not include Step 4 and Step 5.

[0062] Comparative Example 2

[0063] The difference between Comparative Example 2 and Example 1 is that it only includes Step 1.

[0064] The products obtained in Examples 1 - 4 and Comparative Examples 1 - 2 are made into test samples according to the national standard HJ / T299 - 2007. The test sample is the acid leaching solution prepared from the products obtained in Examples 1 - 4 and Comparative Examples 1 - 2. The content of As element in the test sample is measured, and the results are shown in Table 1.

[0065] Table 1 Content of As in the test sample

[0066]

[0067] As can be seen from Table 1, the As content in test samples A - D is 0.005 - 0.012 mg / L, which is much lower than the national standard for toxic hazardous waste (5 mg / L). The hollow spheres prepared in Examples 1 - 4 can be used as industrial material products. The As content in test sample E is 9.439 mg / L, which is higher than the national standard for toxic hazardous waste, indicating that the content of toxic elements in the product prepared in Comparative Example 1 exceeds the national regulation; the As content in test sample F is 15.672 mg / L, and the As content is significantly higher than that in test sample E. Through the analysis of the 6 groups of samples, it can be seen that the preparation of hollow spheres by the plasma spray gun technology can indeed reduce the content of toxic elements in the hollow spheres, and further heat preservation calcination of the hollow spheres can significantly reduce the content of toxic elements.

[0068] The above are only the preferred embodiments of the present invention, and there is no any form of limitation to the present invention. Any equivalent transformation or modification made according to the essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing high-quality hollow spheres using copper smelting waste slag, characterized in that: The main steps include: Step 1: using copper smelting waste slag as the basic raw material, adding an appropriate amount of S, mixing to form a mixture, and grinding the mixture with a ball mill to obtain a powder; Step 2: Forming the powder into a hollow sphere by a plasma spray gun; Step 3: Using an airflow screening machine to screen the hollow spheres; Step 4: Under the protection of inert gas, the hollow spheres obtained by screening are calcined at high temperature to reduce the content of the toxic element As in the hollow spheres; Among them, in step 2, the specific parameters for preparing hollow spheres are: using argon and hydrogen as working gases, the argon pressure is 5-20MPa, the argon flow rate is 60-120L / min, the hydrogen pressure is 10-15MPa, and the hydrogen flow rate is 10-20L / min; the current is 280-680A; the voltage is 90-160V; the powder feeding rate is 1-10kg / min; the plasma spray melting temperature is 8000-10000℃; In step 4, the hollow spheres are calcined at 600-750° C. for 2-10 hours under argon protection, and the tail gas generated during the high-temperature calcination process is filtered through a bag filter.

2. The method for preparing high-quality hollow spheres using copper smelting waste slag according to claim 1, characterized in that: In step 1, the copper smelting waste slag includes the following components in mass percentage: Fe2O3 54%, SiO2 29%, CaO3%, Al2O3 3%, ZnO≤3%, Na4SiO4≤2%, and MgO≤1.5%.

3. The method for preparing high-quality hollow spheres using copper smelting waste slag according to claim 1, characterized in that: In step 1, the amount of S added is 1-5% of the amount of copper smelting waste slag.

4. The method for preparing high-quality hollow spheres using copper smelting waste slag according to claim 1, characterized in that: In step 1, the particle size of the obtained powder is 20-100 μm.

5. The method for preparing high-quality hollow spheres using copper smelting waste slag according to claim 1, characterized in that: In step 2, the hollow spheres are collected with liquid nitrogen at a collection distance of 100-500 mm; the tail gas generated during the preparation process is filtered through a bag filter.

6. The method for preparing high-quality hollow spheres using copper smelting waste slag according to claim 1, characterized in that: The hollow spheres obtained by screening in step three have a particle size of 20-60 μm and a wall thickness of 0.2-3 μm.

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