Preparation method of silver-coated copper powder using acid leaching solution of steel slag

Abstract

The present invention relates to a method for preparing silver-coated copper powder using steel slag acid leaching solution, comprising the following steps: S1: mixing steel slag with acid, stirring and leaching, and filtering to obtain an acid leaching solution; S2: uniformly mixing copper powder with the acid leaching solution obtained in step S1, stirring and reacting, filtering, and drying to obtain pretreated copper powder; S3: mixing the pretreated copper powder obtained in step S2 with a dispersant, a reducing agent, and a complexing agent, heating and stirring, and then adding a silver nitrate solution for reaction. The reaction product is washed and dried to obtain the silver-coated copper powder. This method for preparing silver-coated copper powder using steel slag acid leaching solution utilizes waste steel slag as a raw material to prepare the silver-coated copper powder, achieving secondary utilization of waste, facilitating reduction of environmental pollution, and lowering waste disposal costs. When the waste steel slag acid leaching solution is used for pickling copper, non-metallic phosphorus elements are deposited on the surface of the copper powder to form a phosphating protective film, thereby improving its antioxidant properties.

Description

Technical Field

[0001] The invention relates to the technical field of conductive material preparation, in particular to a method for preparing silver-coated copper powder by utilizing acid leaching solution of steel slag. Background Art

[0002] With the rapid development of the electronics, information and communications industries, the demand for electronic pastes with silver, gold, platinum, copper and other metal powders as the main functional phase is also increasing. Ag has high electrical conductivity and good antioxidant properties. It is a good raw material for the electronics industry and the most widely used conductive metal substance. It is widely used in many fields, but its cost is relatively high. Copper and silver have similar conductivity and lower cost, but its antioxidant properties are poor. The oxide film formed on the surface of metallic copper will affect the conductivity of copper. Studies have found that coating a layer of silver on the surface of copper powder can improve the antioxidant properties of copper powder. The current preparation methods of silver-coated copper powder include electrodeposition, photoinduction, replacement, replacement reduction, etc. Among them, the replacement reduction method is the most widely used. However, this method has the defects of poor adhesion of silver to the copper surface and easy oxidation.

[0003] Steel slag is a waste product produced during the steel production process. It has a high content of iron and other metals, as well as some harmful substances such as heavy metals. The treatment of steel slag has become an important environmental protection task and resource recycling issue.

[0004] Chinese patent CN106148926B discloses silver-coated copper powder and its preparation method. The preparation method first performs an alkaline washing treatment on the copper powder, which can effectively remove impurities such as oxides on the surface of the copper powder and reduce the surface activity of the copper powder particles, thereby obtaining a uniform coated surface and providing a good foundation for subsequent silver coating. During the surface coating treatment, the preparation method adopts a method of first replacing and then reducing to form a uniform and dense silver coating layer on the surface of the copper powder. Finally, the crude silver-coated copper powder product is placed in an acidic cleaning solution for cleaning. The obtained silver-coated copper powder is dense and uniform, and the conductive effect is significantly improved. The traditional silver-coated copper powder preparation method adopted in the above application usually directly uses silver salt as the silver source. The price of silver is relatively high, which makes the preparation cost relatively high. Secondly, there is the problem of uneven silver coating. Silver has poor adhesion to the copper surface and is easily oxidized, resulting in poor antioxidant performance of the silver-coated copper powder. There is no recycling of waste steel slag, which makes resource utilization low and fails to fully tap the potential value of the waste.

[0005] In summary, the traditional method has certain limitations in terms of cost control, uniformity and density of the silver coating, resource utilization efficiency, environmental protection and performance of the final product. The new method of preparing silver-coated copper powder using steel slag acid leaching solution improves the performance of silver-coated copper powder, reduces costs and promotes the recycling of waste by comprehensively utilizing the metal and non-metallic elements in steel slag. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the present invention provides a preparation method of silver-coated copper powder using acid leaching solution of steel slag, which has the advantages of realizing the secondary utilization of waste and solving the problem of relatively high preparation cost.

[0007] To achieve the above object, the present invention provides the following technical solution: a method for preparing silver-coated copper powder using acid leaching solution of steel slag, comprising the following steps:

[0008] S1: mixing steel slag with acid, stirring and leaching, and filtering to obtain acid leaching solution;

[0009] S2: uniformly mixing the copper powder with the acid leaching solution obtained in step S1, stirring for reaction, filtering, and drying to obtain pretreated copper powder;

[0010] S3: mixing the pretreated copper powder obtained in step S2 with a dispersant, a reducing agent and a complexing agent, heating and stirring, and then adding a silver nitrate solution to react. The reaction product is washed and dried to obtain silver-coated copper powder.

[0011] Furthermore, the acid leaching solution contains at least iron ions, vanadium ions, and manganese ions having reducing properties, and the acid leaching solution also contains at least phosphorus, silicon, and sulfur.

[0012] Furthermore, the waste steel slag is plain carbon steel, electrical steel, billet steel or several thereof.

[0013] Furthermore, the mass concentration ratio of the waste steel slag to the dilute sulfuric acid is 1-20 g / L, and the mass fraction of the dilute sulfuric acid is 5-20%.

[0014] Furthermore, the dispersant is one or more of polyvinyl pyrrolidone, polyethylene glycol, polyacrylic acid and polypropylene alcohol, and the concentration of the dispersant is 0.001-0.5 mol / L.

[0015] Furthermore, the reducing agent is one or more of oxalic acid, potassium sodium tartrate, citric acid, hydrazine hydrate, sodium borohydride, gum arabic, glucose, ascorbic acid and glutamic acid, and the concentration of the reducing agent is 0.001-1 mol / L.

[0016] Furthermore, the complexing agent includes one or more of EDTA, EDTA2Na, EDTA4Na, ammonia water, ethylenediamine, diethylenetriamine, triethylenetetramine and tetraethylenepentamine, and the concentration of the complexing agent is 0.01mol / L-1moL / L.

[0017] Furthermore, in step S3, the reaction temperature is controlled to be 30-80° C. when the silver nitrate solution is added for reaction.

[0018] Furthermore, the amount of silver nitrate used is 40%-100% of the mass of the copper powder.

[0019] Compared with the existing technology, the technical solution of this application has the following beneficial effects:

[0020] The preparation method of silver-coated copper powder using acid leaching liquid of steel slag uses waste steel slag as a raw material to prepare the silver-coated copper powder, thereby realizing secondary utilization of waste, being beneficial to reducing environmental pollution and lowering waste treatment costs. The acid leaching liquid of waste steel slag is used for pickling copper, and non-metallic phosphorus elements are deposited on the surface of the copper powder to form a phosphating protective film, thereby improving its anti-oxidation performance. Metal ions are adsorbed on the surface of the copper powder, and some low-valent metal ions can act as reducing agents. After adding a silver nitrate solution, the silver ions are reduced and deposited on the surface of the copper powder, thereby improving the efficiency of reduction deposition. The metal elements and non-metallic elements act synergistically, and the obtained silver-coated copper powder has excellent anti-oxidation performance, higher silver content and coverage rate, good adhesion, good coating density, and good electrical conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the method for preparing silver-coated copper powder using acid leaching solution of waste steel slag according to the present invention;

[0022] Figure 2 This is a scanning electron microscope (SEM) image of the sample obtained in Example 9;

[0023] Figure 3 is a scanning electron microscope (SEM) image of the sample obtained in Example 10;

[0024] Figure 4 The energy dispersive spectrometer (EDS) diagrams of the samples obtained in Example 9 and Example 10 are shown;

[0025] Figure 5 The energy dispersive spectrometer (EDS) diagrams of the samples obtained in Comparative Example 1 and Comparative Example 2 are shown. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] Example 1:

[0028] A method for preparing silver-coated copper powder using an acid leaching solution of steel slag comprises the following steps:

[0029] S1: mixing steel slag with acid, stirring and leaching, and filtering to obtain acid leaching solution;

[0030] S2: uniformly mixing the copper powder with the acid leaching solution obtained in step S1, stirring for reaction, filtering, and drying to obtain pretreated copper powder;

[0031] S3: mixing the pretreated copper powder obtained in step S2 with a dispersant, a reducing agent and a complexing agent, heating and stirring, and then adding a silver nitrate solution to react. The reaction product is washed and dried to obtain silver-coated copper powder.

[0032] Specifically:

[0033] (1) Acid leaching of steel slag: Weigh 1 g of ordinary carbon steel slag with a particle size of <0.1 mm in a beaker, dissolve it in 50 mL of 10% dilute sulfuric acid and stir for 30 min, and filter to obtain the leachate.

[0034] (2) Copper powder pretreatment: Weigh 3 g of spherical copper powder with a particle size of 3.5 μm, add 50 mL of anhydrous ethanol and stir for 10 min to remove organic matter on the surface of the copper powder, then add the leaching solution obtained in step (1) to pickle the copper powder and stir for 1 h, wash with deionized water, and filter to obtain pretreated copper powder.

[0035] (3) Dissolve the pretreated copper powder in 50 mL of deionized water in a 1 L beaker. Add 0.65 g of PVP and 200 mL of deionized water. The PVP concentration in the entire reaction system is 1.0 g / L. Weigh 1.272 g of glucose and 200 mL of deionized water to prepare a glucose solution. Mix the glucose solution with the pretreated copper powder solution and heat and stir.

[0036] (4) Weigh 6.88 g of EDTA and stir with 200 mL of deionized water. Add 2 g of silver nitrate to prepare EDTA-Ag solution.

[0037] (5) When the mixed solution in step (3) is heated to 50°C, the EDTA-Ag solution is quickly poured into it and reacted for 30 minutes.

[0038] (6) The solution after the reaction was filtered to obtain powder, which was washed three times with deionized water. 100 mL of 0.5 mol / L sodium hydroxide solution was added and stirred for 10 min.

[0039] (7) The solution obtained in step (6) was filtered to obtain a powder, which was washed three times with deionized water, with the last ultrasonic treatment lasting 5 minutes and then washed again, and then washed three times with anhydrous ethanol, with the last ultrasonic treatment lasting 5 minutes and then washed again.

[0040] (8) The powder obtained in step (7) was placed in a vacuum oven at 50°C and dried for 3 h to obtain silver-coated copper powder.

[0041] Example 2:

[0042] A method for preparing silver-coated copper powder using an acid leaching solution of steel slag comprises the following steps:

[0043] S1: mixing steel slag with acid, stirring and leaching, and filtering to obtain acid leaching solution;

[0044] S2: uniformly mixing the copper powder with the acid leaching solution obtained in step S1, stirring for reaction, filtering, and drying to obtain pretreated copper powder;

[0045] S3: mixing the pretreated copper powder obtained in step S2 with a dispersant, a reducing agent and a complexing agent, heating and stirring, then adding a silver nitrate solution to react, and washing and drying the reaction product to obtain silver-coated copper powder.

[0046] Specifically:

[0047] (1) Acid leaching of steel slag: Weigh 3 g of ordinary carbon steel slag with a particle size of <0.1 mm in a beaker, dissolve it in 50 mL of 10% dilute sulfuric acid and stir for 30 min, and filter to obtain the leachate.

[0048] (2) Copper powder pretreatment: Weigh 3 g of spherical copper powder with a particle size of 2.5 μm, add the leaching solution obtained in step (1) to pickle the copper powder and stir for 1 h, wash with deionized water, and filter to obtain pretreated copper powder.

[0049] (3) Weigh 0.65 g of PVP, 1.272 g of glucose, and 4.38 g of EDTA2Na, add them to 400 mL of deionized water and stir to dissolve. Add the pretreated copper powder into the solution with 50 mL of deionized water and heat and stir.

[0050] (4) Weigh 2 g of silver nitrate and add 200 mL of deionized water to prepare a silver nitrate solution.

[0051] (5) When the mixed solution in step (3) is heated to 50°C, the silver nitrate solution is quickly poured into it and reacted for 30 minutes.

[0052] (6) The solution after the reaction was filtered to obtain powder, which was washed three times with deionized water. 100 mL of 0.5 mol / L sodium hydroxide solution was added and stirred for 10 min.

[0053] (7) The solution obtained in step (6) was filtered to obtain a powder, which was washed three times with deionized water, with the last ultrasonic treatment lasting 5 minutes and then washed again, and then washed three times with anhydrous ethanol, with the last ultrasonic treatment lasting 5 minutes and then washed again.

[0054] (8) The powder obtained in step (7) was placed in a vacuum oven at 50°C for 3 h to obtain silver-coated copper powder.

[0055] Example 3:

[0056] A method for preparing silver-coated copper powder using an acid leaching solution of steel slag comprises the following steps:

[0057] S1: mixing steel slag with acid, stirring and leaching, and filtering to obtain acid leaching solution;

[0058] S2: uniformly mixing the copper powder with the acid leaching solution obtained in step S1, stirring for reaction, filtering, and drying to obtain pretreated copper powder;

[0059] S3: mixing the pretreated copper powder obtained in step S2 with a dispersant, a reducing agent and a complexing agent, heating and stirring, and then adding a silver nitrate solution to react. The reaction product is washed and dried to obtain silver-coated copper powder.

[0060] Specifically:

[0061] (1) Acid leaching of steel slag: Weigh 3 g of ordinary carbon steel slag with a particle size of 0.1-0.125 mm in a beaker, dissolve it in 50 mL of 10% dilute sulfuric acid and stir for 30 min, and filter to obtain the leachate.

[0062] (2) Copper powder pretreatment: Weigh 3 g of spherical copper powder with a particle size of 2.5 μm, add the leaching solution obtained in step (1) to pickle the copper powder and stir for 1 h, wash with deionized water, and filter to obtain pretreated copper powder.

[0063] (3) Weigh 0.65 g of PVP, 1.272 g of glucose, and 4.38 g of EDTA2Na, add them to 400 mL of deionized water and stir to dissolve. Add the pretreated copper powder into the solution with 50 mL of deionized water and heat and stir.

[0064] (4) Weigh 2 g of silver nitrate and add 200 mL of deionized water to prepare a silver nitrate solution.

[0065] (5) When the mixed solution in step (3) is heated to 50°C, the silver nitrate solution is quickly poured into it and reacted for 30 minutes.

[0066] (6) The solution after the reaction was filtered to obtain powder, which was washed three times with deionized water. 100 mL of 0.5 mol / L sodium hydroxide solution was added and stirred for 10 min.

[0067] (7) The solution obtained in step (6) was filtered to obtain a powder, which was washed three times with deionized water, with the last ultrasonic treatment lasting 5 minutes and then washed again, and then washed three times with anhydrous ethanol, with the last ultrasonic treatment lasting 5 minutes and then washed again.

[0068] (8) The powder obtained in step (7) was placed in a vacuum oven at 50°C for 3 h to obtain silver-coated copper powder.

[0069] Example 4:

[0070] A method for preparing silver-coated copper powder using an acid leaching solution of steel slag comprises the following steps:

[0071] S1: mixing steel slag with acid, stirring and leaching, and filtering to obtain acid leaching solution;

[0072] S2: uniformly mixing the copper powder with the acid leaching solution obtained in step S1, stirring for reaction, filtering, and drying to obtain pretreated copper powder;

[0073] S3: mixing the pretreated copper powder obtained in step S2 with a dispersant, a reducing agent and a complexing agent, heating and stirring, and then adding a silver nitrate solution to react. The reaction product is washed and dried to obtain silver-coated copper powder.

[0074] Specifically:

[0075] (1) Acid leaching of steel slag: Weigh 5 g of ordinary carbon steel slag with a particle size of 0.1-0.125 mm in a beaker, dissolve it in 50 mL of 10% dilute sulfuric acid and stir for 30 min, and filter to obtain the leachate.

[0076] (2) Copper powder pretreatment: Weigh 3 g of spherical copper powder with a particle size of 2.5 μm, add the leaching solution obtained in step (1) to pickle the copper powder and stir for 1 h, wash with deionized water, and filter to obtain pretreated copper powder.

[0077] (3) Weigh 0.65 g of PVP, 1.272 g of glucose, and 4.38 g of EDTA2Na, add them to 400 mL of deionized water and stir to dissolve. Add the pretreated copper powder into the solution with 50 mL of deionized water and heat and stir.

[0078] (4) Weigh 2 g of silver nitrate and add 200 mL of deionized water to prepare a silver nitrate solution.

[0079] (5) When the mixed solution in step (3) is heated to 50°C, the silver nitrate solution is quickly poured into it and reacted for 30 minutes.

[0080] (6) The solution after the reaction was filtered to obtain powder, which was washed three times with deionized water. 100 mL of 0.5 mol / L sodium hydroxide solution was added and stirred for 10 min.

[0081] (7) The solution obtained in step (6) was filtered to obtain a powder, which was washed three times with deionized water, with the last ultrasonic treatment lasting 5 minutes and then washed again, and then washed three times with anhydrous ethanol, with the last ultrasonic treatment lasting 5 minutes and then washed again.

[0082] (8) The powder obtained in step (7) was placed in a vacuum oven at 50°C for 3 h to obtain silver-coated copper powder.

[0083] Embodiment 5:

[0084] A method for preparing silver-coated copper powder using an acid leaching solution of steel slag comprises the following steps:

[0085] S1: mixing steel slag with acid, stirring and leaching, and filtering to obtain acid leaching solution;

[0086] S2: uniformly mixing the copper powder with the acid leaching solution obtained in step S1, stirring for reaction, filtering, and drying to obtain pretreated copper powder;

[0087] S3: mixing the pretreated copper powder obtained in step S2 with a dispersant, a reducing agent and a complexing agent, heating and stirring, and then adding a silver nitrate solution to react. The reaction product is washed and dried to obtain silver-coated copper powder.

[0088] Specifically:

[0089] (1) Acid leaching of steel slag: Weigh 3 g of ordinary carbon steel slag with a particle size of 0.125-0.2 mm in a beaker, dissolve it in 50 mL of 10% dilute sulfuric acid and stir for 30 min, and filter to obtain the leachate.

[0090] (2) Copper powder pretreatment: Weigh 3 g of spherical copper powder with a particle size of 2.5 μm, add the leaching solution obtained in step (1) to pickle the copper powder and stir for 1 h, wash with deionized water, and filter to obtain pretreated copper powder.

[0091] (3) Weigh 0.65 g of PVP, 1.272 g of glucose, and 4.38 g of EDTA2Na, add them to 400 mL of deionized water and stir to dissolve. Add the pretreated copper powder into the solution with 50 mL of deionized water and heat and stir.

[0092] (4) Weigh 2 g of silver nitrate and add 200 mL of deionized water to prepare a silver nitrate solution.

[0093] (5) When the mixed solution in step (3) is heated to 50°C, the silver nitrate solution is quickly poured into it and reacted for 30 minutes.

[0094] (6) The solution after the reaction was filtered to obtain powder, which was washed three times with deionized water. 100 mL of 0.5 mol / L sodium hydroxide solution was added and stirred for 10 min.

[0095] (7) The solution obtained in step (6) was filtered to obtain a powder, which was washed three times with deionized water, with the last ultrasonic treatment lasting 5 minutes and then washed again, and then washed three times with anhydrous ethanol, with the last ultrasonic treatment lasting 5 minutes and then washed again.

[0096] (8) The powder obtained in step (7) was placed in a vacuum oven at 50°C for 3 h to obtain silver-coated copper powder.

[0097] Example 6:

[0098] A method for preparing silver-coated copper powder using an acid leaching solution of steel slag comprises the following steps:

[0099] S1: mixing steel slag with acid, stirring and leaching, and filtering to obtain acid leaching solution;

[0100] S2: uniformly mixing the copper powder with the acid leaching solution obtained in step S1, stirring for reaction, filtering, and drying to obtain pretreated copper powder;

[0101] S3: mixing the pretreated copper powder obtained in step S2 with a dispersant, a reducing agent and a complexing agent, heating and stirring, and then adding a silver nitrate solution to react. The reaction product is washed and dried to obtain silver-coated copper powder.

[0102] Specifically:

[0103] (1) Acid leaching of steel slag: Weigh 3 g of ordinary carbon steel slag with a particle size > 0.3 mm in a beaker, dissolve it in 50 mL of 10% dilute sulfuric acid and stir for 30 min, and filter to obtain the leachate.

[0104] (2) Copper powder pretreatment: Weigh 3 g of spherical copper powder with a particle size of 2.5 μm, add the leaching solution obtained in step (1) to pickle the copper powder and stir for 1 h, wash with deionized water, and filter to obtain pretreated copper powder.

[0105] (3) Weigh 0.65 g of PVP, 1.272 g of glucose, and 4.38 g of EDTA2Na, add them to 400 mL of deionized water and stir to dissolve. Add the pretreated copper powder into the solution with 50 mL of deionized water and heat and stir.

[0106] (4) Weigh 2 g of silver nitrate and add 200 mL of deionized water to prepare a silver nitrate solution.

[0107] (5) When the mixed solution in step (3) is heated to 40°C, the silver nitrate solution is quickly poured into it and reacted for 30 minutes.

[0108] (6) The solution after the reaction was filtered to obtain powder, which was washed three times with deionized water. 100 mL of 0.5 mol / L sodium hydroxide solution was added and stirred for 10 min.

[0109] (7) The solution obtained in step (6) was filtered to obtain a powder, which was washed three times with deionized water, with the last ultrasonic treatment lasting 5 minutes and then washed again, and then washed three times with anhydrous ethanol, with the last ultrasonic treatment lasting 5 minutes and then washed again.

[0110] (8) The powder obtained in step (7) was placed in a vacuum oven at 50°C for 3 h to obtain silver-coated copper powder.

[0111] Embodiment seven:

[0112] A method for preparing silver-coated copper powder using an acid leaching solution of steel slag comprises the following steps:

[0113] S1: mixing steel slag with acid, stirring and leaching, and filtering to obtain acid leaching solution;

[0114] S2: uniformly mixing the copper powder with the acid leaching solution obtained in step S1, stirring for reaction, filtering, and drying to obtain pretreated copper powder;

[0115] S3: mixing the pretreated copper powder obtained in step S2 with a dispersant, a reducing agent and a complexing agent, heating and stirring, and then adding a silver nitrate solution to react. The reaction product is washed and dried to obtain silver-coated copper powder.

[0116] Specifically:

[0117] (1) Acid leaching of steel slag: Weigh 1 g of electrical steel slag with a particle size of <0.1 mm in a beaker, dissolve it in 50 mL of 10% dilute sulfuric acid and stir for 30 min, and filter to obtain the leachate.

[0118] (2) Copper powder pretreatment: Weigh 3 g of spherical copper powder with a particle size of 3.5 μm, add 50 mL of anhydrous ethanol and stir for 10 min to remove organic matter on the surface of the copper powder, then add the leaching solution obtained in step (1) to pickle the copper powder and stir for 1 h, wash with deionized water, and filter to obtain pretreated copper powder.

[0119] (3) Dissolve the pretreated copper powder in 50 mL of deionized water in a 1 L beaker. Add 0.65 g of PVP and 200 mL of deionized water. The PVP concentration in the entire reaction system is 1.0 g / L. Weigh 1.272 g of glucose and 200 mL of deionized water to prepare a glucose solution. Mix the glucose solution with the pretreated copper powder solution and heat and stir.

[0120] (4) Weigh 6.88 g of EDTA and stir with 200 mL of deionized water. Add 2 g of silver nitrate to prepare EDTA-Ag solution.

[0121] (5) When the mixed solution in step (3) is heated to 50°C, the EDTA-Ag solution is quickly poured into it and reacted for 30 minutes.

[0122] (6) The solution after the reaction was filtered to obtain powder, which was washed three times with deionized water. 100 mL of 0.5 mol / L sodium hydroxide solution was added and stirred for 10 min.

[0123] (7) The solution obtained in step (6) was filtered to obtain a powder, which was washed three times with deionized water, with the last ultrasonic treatment lasting 5 minutes and then washed again, and then washed three times with anhydrous ethanol, with the last ultrasonic treatment lasting 5 minutes and then washed again.

[0124] (8) The powder obtained in step (7) was placed in a vacuum oven at 50°C for 3 h to obtain silver-coated copper powder.

[0125] Embodiment 8:

[0126] A method for preparing silver-coated copper powder using an acid leaching solution of steel slag comprises the following steps:

[0127] S1: mixing steel slag with acid, stirring and leaching, and filtering to obtain acid leaching solution;

[0128] S2: uniformly mixing the copper powder with the acid leaching solution obtained in step S1, stirring for reaction, filtering, and drying to obtain pretreated copper powder;

[0129] S3: mixing the pretreated copper powder obtained in step S2 with a dispersant, a reducing agent and a complexing agent, heating and stirring, and then adding a silver nitrate solution to react. The reaction product is washed and dried to obtain silver-coated copper powder.

[0130] Specifically:

[0131] (1) Acid leaching of steel slag: Weigh 3 g of electrical steel slag with a particle size of <0.1 mm in a beaker, dissolve it in 50 mL of 10% dilute sulfuric acid and stir for 30 min, and filter to obtain the leachate.

[0132] (2) Copper powder pretreatment: Weigh 3 g of spherical copper powder with a particle size of 2.5 μm, add the leaching solution obtained in step (1) to pickle the copper powder and stir for 1 h, wash with deionized water, and filter to obtain pretreated copper powder.

[0133] (3) Weigh 0.65 g of PVP, 1.272 g of glucose, and 4.38 g of EDTA2Na, add them to 400 mL of deionized water and stir to dissolve. Add the pretreated copper powder into the solution with 50 mL of deionized water and heat and stir.

[0134] (4) Weigh 2 g of silver nitrate and add 200 mL of deionized water to prepare a silver nitrate solution.

[0135] (5) When the mixed solution in step (3) is heated to 50°C, the silver nitrate solution is quickly poured into it and reacted for 30 minutes.

[0136] (6) The solution after the reaction was filtered to obtain powder, which was washed three times with deionized water. 100 mL of 0.5 mol / L sodium hydroxide solution was added and stirred for 10 min.

[0137] (7) The solution obtained in step (6) was filtered to obtain a powder, which was washed three times with deionized water, with the last ultrasonic treatment lasting 5 minutes and then washed again, and then washed three times with anhydrous ethanol, with the last ultrasonic treatment lasting 5 minutes and then washed again.

[0138] (8) The powder obtained in step (7) was placed in a vacuum oven at 50°C for 3 h to obtain silver-coated copper powder.

[0139] Embodiment 9:

[0140] A method for preparing silver-coated copper powder using an acid leaching solution of steel slag comprises the following steps:

[0141] S1: mixing steel slag with acid, stirring and leaching, and filtering to obtain acid leaching solution;

[0142] S2: uniformly mixing the copper powder with the acid leaching solution obtained in step S1, stirring for reaction, filtering, and drying to obtain pretreated copper powder;

[0143] S3: mixing the pretreated copper powder obtained in step S2 with a dispersant, a reducing agent and a complexing agent, heating and stirring, and then adding a silver nitrate solution to react. The reaction product is washed and dried to obtain silver-coated copper powder.

[0144] Specifically:

[0145] (1) Acid leaching of steel slag: Weigh 3 g of electrical steel slag with a particle size of 0.125-0.15 mm in a beaker, dissolve it in 50 mL of 10% dilute sulfuric acid and stir for 30 min, and filter to obtain the leachate.

[0146] (2) Copper powder pretreatment: Weigh 3 g of spherical copper powder with a particle size of 2.5 μm, add the leaching solution obtained in step (1) to pickle the copper powder and stir for 1 h, wash with deionized water, and filter to obtain pretreated copper powder.

[0147] (3) Weigh 0.65 g of PVP, 1.272 g of glucose, and 6.88 g of EDTA, add them to 400 mL of deionized water and stir to dissolve. Add the pretreated copper powder into the solution with 50 mL of deionized water and heat and stir.

[0148] (4) Weigh 2 g of silver nitrate and add 200 mL of deionized water to prepare a silver nitrate solution.

[0149] (5) When the mixed solution in step (3) is heated to 50°C, the silver nitrate solution is added dropwise at a rate of 5 mL / min using a peristaltic pump. After the addition is complete, the mixture is reacted for 10 minutes.

[0150] (6) The solution after the reaction was filtered to obtain powder, which was washed three times with deionized water. 100 mL of 0.5 mol / L sodium hydroxide solution was added and stirred for 10 min.

[0151] (7) The solution obtained in step (6) was filtered to obtain a powder, which was washed three times with deionized water, with the last ultrasonic treatment lasting 5 minutes and then washed again, and then washed three times with anhydrous ethanol, with the last ultrasonic treatment lasting 5 minutes and then washed again.

[0152] (8) The powder obtained in step (7) was placed in a vacuum oven at 50°C for 3 h to obtain silver-coated copper powder.

[0153] Embodiment 10:

[0154] A method for preparing silver-coated copper powder using an acid leaching solution of steel slag comprises the following steps:

[0155] S1: mixing steel slag with acid, stirring and leaching, and filtering to obtain acid leaching solution;

[0156] S2: uniformly mixing the copper powder with the acid leaching solution obtained in step S1, stirring for reaction, filtering, and drying to obtain pretreated copper powder;

[0157] S3: mixing the pretreated copper powder obtained in step S2 with a dispersant, a reducing agent and a complexing agent, heating and stirring, and then adding a silver nitrate solution to react. The reaction product is washed and dried to obtain silver-coated copper powder.

[0158] Specifically:

[0159] (1) Acid leaching of steel slag: Weigh 3 g of electrical steel slag with a particle size of 0.125-0.15 mm in a beaker, dissolve it in 50 mL of 10% dilute sulfuric acid and stir for 30 min, and filter to obtain the leachate.

[0160] (2) Copper powder pretreatment: Weigh 3 g of spherical copper powder with a particle size of 2.5 μm, add the leaching solution obtained in step (1) to pickle the copper powder and stir for 1 h, wash with deionized water, and filter to obtain pretreated copper powder.

[0161] (3) Weigh 0.65 g of PVP, 1.272 g of glucose, and 4.38 g of EDTA2Na, add them to 400 mL of deionized water and stir to dissolve. Add the pretreated copper powder into the solution with 50 mL of deionized water and heat and stir.

[0162] (4) Weigh 2 g of silver nitrate and add 200 mL of deionized water to prepare a silver nitrate solution.

[0163] (5) When the mixed solution in step (3) is heated to 50°C, the silver nitrate solution is added dropwise at a rate of 5 mL / min using a peristaltic pump. After the addition is complete, the mixture is reacted for 10 minutes.

[0164] (6) The solution after the reaction was filtered to obtain powder, which was washed three times with deionized water. 100 mL of 0.5 mol / L sodium hydroxide solution was added and stirred for 10 min.

[0165] (7) The solution obtained in step (6) was filtered to obtain a powder, which was washed three times with deionized water, with the last ultrasonic treatment lasting 5 minutes and then washed again, and then washed three times with anhydrous ethanol, with the last ultrasonic treatment lasting 5 minutes and then washed again.

[0166] (8) The powder obtained in step (7) was placed in a vacuum oven at 50°C for 3 h to obtain silver-coated copper powder.

[0167] In the above examples, sulfuric acid was used at a mass fraction of 10% in an amount of 50 mL; copper powder was used in an amount of 3 g; the dispersant was polyvinyl pyrrolidone in an amount of 0.65 g; the reducing agent was glucose in an amount of 1.272 g; and silver nitrate was used in an amount of 2 g. The temperature at the time of adding the silver nitrate and the oven temperature were both 50° C. The remaining variable conditions are shown in Table 1.

[0168] Table 1: Variables in Examples

[0169] Serial number Types of steel slag Steel slag particle size / mm Steel slag dosage / g Copper powder particle size / μm Types of complexing agents Complexing agent dosage / g Silver nitrate addition rate 1 Plain carbon steel <0.1 1 3.5 EDTA 6.88 Quick Pour 2 Plain carbon steel <0.1 3 2.5 EDTA2Na 4.38 Quick Pour 3 Plain carbon steel 0.1-0.125 3 2.5 EDTA2Na 4.38 Quick Pour 4 Plain carbon steel 0.1-0.125 5 2.5 EDTA2Na 4.38 Quick Pour 5 Plain carbon steel 0.125-0.2 3 2.5 EDTA2Na 4.38 Quick Pour 6 Plain carbon steel >0.3 3 2.5 EDTA2Na 4.38 Quick Pour 7 electrical steel <0.1 1 3.5 EDTA 6.88 Quick Pour 8 electrical steel <0.1 3 2.5 EDTA2Na 4.38 Quick Pour 9 electrical steel 0.125-0.15 3 2.5 EDTA 6.88 5mL / min 10 electrical steel 0.125-0.15 3 2.5 EDTA2Na 4.38 5mL / min

[0170] Comparative Example 1:

[0171] (1) Copper powder pretreatment: Weigh 3 g of spherical copper powder with a particle size of 2.5 μm, add 50 ml of 10% dilute sulfuric acid to pickle the copper powder and stir for 1 h, wash with deionized water, and filter to obtain pretreated copper powder.

[0172] (2) Weigh 0.65 g of PVP, 1.272 g of glucose, and 6.88 g of EDTA, add them to 400 mL of deionized water, and stir to dissolve. Add the pretreated copper powder into the solution with 50 mL of deionized water, and heat and stir.

[0173] (3) Weigh 2 g of silver nitrate and add 200 mL of deionized water to prepare a silver nitrate solution.

[0174] (4) When the mixed solution in step (2) is heated to 50°C, the silver nitrate solution is added dropwise at a rate of 5 mL / min using a peristaltic pump. After the addition is complete, the mixture is reacted for 10 minutes.

[0175] (5) The solution after the reaction was filtered to obtain powder, which was washed three times with deionized water. 100 mL of 0.5 mol / L sodium hydroxide solution was added and stirred for 10 min.

[0176] (6) The solution obtained in step (5) was filtered to obtain a powder, which was washed three times with deionized water, the last time with ultrasonic treatment for 5 minutes, and then washed again. The powder was then washed three times with anhydrous ethanol, the last time with ultrasonic treatment for 5 minutes.

[0177] (7) The powder obtained in step (6) was placed in a vacuum oven at 50°C for 3 h to obtain silver-coated copper powder.

[0178] Comparative Example 2:

[0179] (1) Copper powder pretreatment: Weigh 3 g of spherical copper powder with a particle size of 2.5 μm, add 50 ml of 10% dilute sulfuric acid to pickle the copper powder and stir for 1 h, wash with deionized water, and filter to obtain pretreated copper powder.

[0180] (2) Weigh 0.65 g of PVP, 1.272 g of glucose and 4.38 g of EDTA2Na and add them to 400 mL of deionized water and stir to dissolve. Add the pretreated copper powder into the solution with 50 mL of deionized water and heat and stir.

[0181] (3) Weigh 2 g of silver nitrate and add 200 mL of deionized water to prepare a silver nitrate solution.

[0182] (4) When the mixed solution in step (2) is heated to 50°C, the silver nitrate solution is added dropwise at a rate of 5 mL / min using a peristaltic pump. After the addition is complete, the mixture is reacted for 10 minutes.

[0183] (5) The solution after the reaction was filtered to obtain powder, which was washed three times with deionized water. 100 mL of 0.5 mol / L sodium hydroxide solution was added and stirred for 10 min.

[0184] (6) The solution obtained in step (5) was filtered to obtain a powder, which was washed three times with deionized water, the last time with ultrasonic treatment for 5 minutes, and then washed again. The powder was then washed three times with anhydrous ethanol, the last time with ultrasonic treatment for 5 minutes.

[0185] (7) The powder obtained in step (6) was placed in a vacuum oven at 50°C for 3 h to obtain silver-coated copper powder.

[0186] Coverage performance test: The coverage of silver-coated copper powder is calculated by EDS analysis. The element copper is set to red and the element silver is set to green. If the green area of ​​the ball exceeds half of the total area, it is considered to be coated. If the red area of ​​the ball exceeds half of the total area of ​​the ball, it is considered to be uncoated. .

[0187] Table 2 Coverage rate data of some examples and comparative examples

[0188] Example Coverage Example 9 95.15% Example 10 93.58% Comparative Example 1 85.91% Comparative Example 2 79.60%

[0189] As shown in Table 2 Figure 4 、 Figure 5 The calculated coverage rates for Examples 9 and 10 and Comparative Examples 1 and 2 showed that the coverage rates of the silver-coated copper powders obtained in Examples 9 and 10 were 95.13% and 93.58%, respectively, and the coverage rates of the silver-coated copper powders obtained in Comparative Examples 1 and 2 were 85.91% and 79.60%, respectively. Therefore, the coverage rate of the silver-coated copper powder obtained by treating with steel slag leachate was significantly higher than that of the silver-coated copper powder obtained in the comparative example without treating with steel slag.

[0190] In the scheme of the present invention, the mass concentration ratio of steel slag to dilute sulfuric acid is preferably 1-200 g / L. If it is too low, the ions in the leachate will be too few and difficult to adsorb on the surface of the copper powder. If it is too high, the steel slag will consume too much acid and it will be difficult to clean the oxides on the surface of the copper powder. The mass fraction of dilute sulfuric acid is preferably 5-40%. If it is too low, the reaction rate will be reduced and the reaction may be incomplete. If it is too high, the reaction will be too intense and difficult to control.

[0191] The concentration of the dispersant in the solution of the present invention is preferably 0.001-0.5 mol / L. Too low a concentration results in poor dispersion effect, while too high a concentration results in system instability and increased costs.

[0192] The concentration of the reducing agent in the solution of the present invention is preferably 0.001-1 mol / L. Too low a concentration leads to poor reducing ability, while too high a concentration leads to an abnormally accelerated reaction rate, resulting in the formation of silver and increased costs.

[0193] The concentration of the complexing agent in the solution of the present invention is preferably 0.01 mol / L-1 mol / L. If it is too low, the complexing ability will be poor and silver will be easily generated. If it is too high, the reaction rate will be too slow and the cost will be increased.

[0194] In the scheme of the present invention, the reaction temperature is preferably controlled at 30-80°C. Too low a temperature leads to a slow reaction rate, while too high a temperature leads to an overly intense reaction that is difficult to control.

[0195] The amount of silver nitrate used in the solution of the present invention is preferably 40%-100% of the mass of the copper powder. If it is too low, the surface of the copper powder will be less coated and the antioxidant performance will be poor. If it is too high, silver nitrate will be generated.

[0196] The working principle of the above embodiment is as follows: steelmaking slag is acid-leached, and some metal elements (such as iron ions, vanadium ions, manganese ions, titanium ions, calcium ions, etc.) and non-metallic elements (such as phosphorus, silicon, sulfur, etc.) contained in the slag enter the solution. The copper powder is pickled with the acid leaching solution. While the pickling removes oxides on the surface of the copper powder, some metal ions (such as iron ions, vanadium ions, manganese ions, titanium ions, calcium ions, etc.) and non-metallic elements (such as phosphorus, silicon, sulfur, etc.) contained in the acid leaching solution are adsorbed on the surface of the copper powder. Among them, the low-valent iron ions, vanadium ions, and manganese ions in the metal ions reduce silver ions, and the resulting silver element is deposited on the surface of the copper powder to form silver crystal nuclei, making the deposition of silver ions faster and more accurate. After the addition of silver nitrate solution, the silver ions are reduced and deposited in situ on the surface of the copper powder, thereby improving the efficiency of reduction deposition. In addition, the copper and non-metallic elements, as well as the above metal ions, can form a phosphating film on the surface of the copper powder with non-metallic elements such as phosphorus, which can cover the areas not coated by the silver element and has an antioxidant effect. The reducing effect of the metal elements during the reaction process improves the deposition rate and accuracy of the silver element, and the film formed by the metal ions and the non-metallic elements protects the uncoated area from oxidation, which has a synergistic effect on the antioxidant performance of the copper powder during the reaction. As a result, the silver-coated copper powder prepared by the present invention has a high coverage rate and silver content, good density and antioxidant performance, and better conductive performance.

[0197] Furthermore, in order to ensure the synergistic effect of the above-mentioned metal elements and non-metallic elements, the present invention further limits the dropping rate of silver nitrate in step S3 to 5 mL / min, and first adds a portion of silver nitrate in step S2, then adds reducing agents and other reagents, and then adds silver nitrate.

[0198] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0199] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing silver-coated copper powder using acid leaching solution of steel slag, characterized in that: The following steps are involved: S1: mixing waste steel slag with acid, stirring and leaching, and filtering to obtain acid leaching solution; S2: uniformly mixing the copper powder with the acid leaching solution obtained in step S1, stirring for reaction, filtering, and drying to obtain pretreated copper powder; S3: mixing the pretreated copper powder obtained in step S2 with a dispersant, a reducing agent, and a complexing agent, heating and stirring, then adding a silver nitrate solution to react, washing and drying the reaction product to obtain silver-coated copper powder; The acid leaching solution contains at least one of iron ions, vanadium ions, and manganese ions having reducing properties, and the acid leaching solution also contains at least one of phosphorus, silicon, and sulfur; The mass concentration ratio of the waste steel slag to the dilute sulfuric acid is 1-20 g / L, and the mass fraction of the dilute sulfuric acid is 5-20%.

2. The method for preparing silver-coated copper powder by using acid leaching solution of steel slag according to claim 1, characterized in that: The waste steel slag is one or more of ordinary carbon steel, electrical steel, and billet steel.

3. The method for preparing silver-coated copper powder by using acid leaching solution of steel slag according to claim 1, characterized in that: The dispersant is one or more of polyvinyl pyrrolidone, polyethylene glycol, polyacrylic acid and polypropylene alcohol, and the concentration of the dispersant is 0.001-0.5 mol / L.

4. The method for preparing silver-coated copper powder by using acid leaching solution of steel slag according to claim 1, characterized in that: The reducing agent is one or more of oxalic acid, potassium sodium tartrate, citric acid, hydrazine hydrate, sodium borohydride, gum arabic, glucose, ascorbic acid and glutamic acid, and the concentration of the reducing agent is 0.001-1 mol / L.

5. The method for preparing silver-coated copper powder by utilizing acid leaching solution of steel slag according to claim 1, characterized in that: The complexing agent includes one or more of EDTA, EDTA2Na, EDTA4Na, ammonia water, ethylenediamine, diethylenetriamine, triethylenetetramine and tetraethylenepentamine, and the concentration of the complexing agent is 0.01mol / L-1moL / L.

6. The method for preparing silver-coated copper powder by utilizing acid leaching solution of steel slag according to claim 1, characterized in that: When adding the silver nitrate solution in step S3, the reaction temperature is controlled to be 30-80°C.

7. The method for preparing silver-coated copper powder by utilizing acid leaching solution of steel slag according to claim 1, characterized in that: The amount of silver nitrate used is 40%-100% of the mass of the copper powder.

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