Method for preparing silver-coated copper powder by using steel slag acid leaching solution

Abstract

The invention relates to a preparation method for preparing silver-coated copper powder by using a steel slag acid leaching solution. The preparation method comprises the following steps: S1, mixing steel slag with acid, stirring and leaching, and filtering to obtain the acid leaching solution; s2, copper powder and the acid leaching solution obtained in the step S1 are evenly mixed, after stirring reaction, filtering and drying are conducted, and pretreated copper powder is obtained; and S3, the pretreated copper powder obtained in the step S2 is mixed with a dispersing agent, a reducing agent and a complexing agent, the mixture is heated and stirred, then a silver nitrate solution is added for a reaction, a reaction product is washed and dried, and the silver-coated copper powder is obtained. According to the preparation method for preparing the silver-coated copper powder through the steel slag acid leaching solution, the waste steel slag is used as the raw material for preparing the silver-coated copper powder, secondary utilization of waste is achieved, environmental pollution is reduced, the waste treatment cost is reduced, the acid leaching solution of the waste steel slag is used for pickling copper, and the production cost is reduced. The nonmetal phosphorus element can be deposited on the surface of the copper powder to form a layer of phosphating protective film, and the oxidation resistance of the copper powder can be improved.

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 steel slag acid leaching solution. Background Art

[0002] With the rapid development of electronics, information and communication 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 electronic industry and the most widely used conductive metal substance. It is widely used in many fields, but its cost is relatively high. Copper has similar conductivity to silver 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. Currently, the 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 on the copper surface and easy oxidation.

[0003] Steel slag is a waste generated 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. my country's steel slag treatment industry has become an indispensable environmental protection industry. The annual output of domestic steel slag exceeds 200 million tons, of which about 1 / 3 is open-hearth slag, 1 / 3 is converter slag, 1 / 6 is electric furnace slag, and there is a small amount of stainless steel slag, process slag, molten iron slag, etc. If these wastes are not properly handled, they will cause serious pollution and damage to the environment.

[0004] Chinese patent CN106148926B discloses silver-coated copper powder and a preparation method thereof. The preparation method can effectively remove impurities such as oxides on the surface of the copper powder by first subjecting the copper powder to alkaline washing treatment, and reduce the surface activity of the copper powder particles to obtain a uniform coated surface, which provides a good foundation for subsequent silver coating. In the surface coating treatment process, the preparation method adopts a method of first replacement and then reduction to form a uniform and dense silver coating layer on the surface of the copper powder. Finally, the crude product of the silver-coated copper powder is placed in an acidic cleaning solution for cleaning, and 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 used in the above application usually directly uses silver salt as the silver source, and the price of silver is relatively high, which makes the preparation cost relatively high. Secondly, there is a problem of uneven silver coating, and silver has poor adhesion to the copper surface and is easily oxidized, resulting in poor antioxidant performance of the silver-coated copper powder. The reuse of waste steel slag is not involved, which makes the resource utilization rate low and fails to fully tap the potential value of the waste.

[0005] In summary, the traditional method has certain limitations in cost control, uniformity and density of the silver coating layer, 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-metal elements in the steel slag. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a method for preparing silver-coated copper powder by using steel slag acid leaching solution, 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 steel slag acid leaching solution, comprising the following steps:

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

[0009] S2: uniformly mixing the copper powder and 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 a 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 0.01 mol / L-1 mol / L.

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

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

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

[0020] The method for preparing silver-coated copper powder by using steel slag acid leaching liquid uses waste steel slag as a raw material to prepare the silver-coated copper powder, thereby realizing the secondary utilization of waste, being beneficial to reducing environmental pollution and reducing 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, and after adding a silver nitrate solution, the reduced silver ions are 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 coating rate, good adhesion, good coating density and good electrical conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of a method for preparing silver-coated copper powder by 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 spectrum (EDS) diagram of the samples obtained in Example 9 and Example 10;

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

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0027] Embodiment 1:

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

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

[0030] S2: uniformly mixing the copper powder and 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 a 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) Pretreatment of copper powder: 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) Use 50 mL of deionized water to flush the pretreated copper powder into a 1 L beaker, add 0.65 g of PVP and 200 mL of deionized water, and 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, then add 2 g of silver nitrate to prepare an 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, and 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 before washing again, and then washed three times with anhydrous ethanol, with the last ultrasonic treatment lasting 5 minutes before washing 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] Embodiment 2:

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

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

[0044] S2: uniformly mixing the copper powder and 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, and then adding a silver nitrate solution to react. The reaction product is washed and dried to obtain a 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 leaching solution.

[0048] (2) Pretreatment of copper powder: 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 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 the mixed solution 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, and 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 before washing again, and then washed three times with anhydrous ethanol, with the last ultrasonic treatment lasting 5 minutes before washing again.

[0054] (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.

[0055] Embodiment three:

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

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

[0058] S2: uniformly mixing the copper powder and 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 a 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 leaching solution.

[0062] (2) Pretreatment of copper powder: 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 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 the mixed solution 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, and 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 before washing again, and then washed three times with anhydrous ethanol, with the last ultrasonic treatment lasting 5 minutes before washing again.

[0068] (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.

[0069] Embodiment 4:

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

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

[0072] S2: uniformly mixing the copper powder and 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 a 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 leaching solution.

[0076] (2) Pretreatment of copper powder: 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 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 the mixed solution 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, and 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 before washing again, and then washed three times with anhydrous ethanol, with the last ultrasonic treatment lasting 5 minutes before washing again.

[0082] (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.

[0083] Embodiment five:

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

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

[0086] S2: uniformly mixing the copper powder and 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 a 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 leaching solution.

[0090] (2) Pretreatment of copper powder: 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 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 the mixed solution 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, and 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 before washing again, and then washed three times with anhydrous ethanol, with the last ultrasonic treatment lasting 5 minutes before washing again.

[0096] (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.

[0097] Embodiment six:

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

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

[0100] S2: uniformly mixing the copper powder and 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 a 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 of >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 leaching solution.

[0104] (2) Pretreatment of copper powder: 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 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 the mixed solution 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, and 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 before washing again, and then washed three times with anhydrous ethanol, with the last ultrasonic treatment lasting 5 minutes before washing again.

[0110] (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.

[0111] Embodiment seven:

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

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

[0114] S2: uniformly mixing the copper powder and 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 a 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) Pretreatment of copper powder: 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) Use 50 mL of deionized water to flush the pretreated copper powder into a 1 L beaker, add 0.65 g of PVP and 200 mL of deionized water, and 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, then add 2 g of silver nitrate to prepare an 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, and 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 before washing again, and then washed three times with anhydrous ethanol, with the last ultrasonic treatment lasting 5 minutes before washing again.

[0124] (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.

[0125] Embodiment eight:

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

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

[0128] S2: uniformly mixing the copper powder and 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 a 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) Pretreatment of copper powder: 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 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 the mixed solution 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, and 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 before washing again, and then washed three times with anhydrous ethanol, with the last ultrasonic treatment lasting 5 minutes before washing again.

[0138] (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.

[0139] Embodiment nine:

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

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

[0142] S2: uniformly mixing the copper powder and 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 a 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) Pretreatment of copper powder: 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 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, and 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 before washing again, and then washed three times with anhydrous ethanol, with the last ultrasonic treatment lasting 5 minutes before washing again.

[0152] (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.

[0153] Embodiment ten:

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

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

[0156] S2: uniformly mixing the copper powder and 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 a 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) Pretreatment of copper powder: 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 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, and 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 before washing again, and then washed three times with anhydrous ethanol, with the last ultrasonic treatment lasting 5 minutes before washing again.

[0166] (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.

[0167] The sulfuric acid used in the above embodiments is 10% by mass and 50 mL in amount; the copper powder is 3 g in amount; the dispersant is polyvinyl pyrrolidone in amount 0.65 g; the reducing agent is glucose in amount 1.272 g; the silver nitrate is 2 g; the temperature when adding silver nitrate and the oven temperature are both 50°C. The other variable conditions are shown in Table 1.

[0168] Table 1: Variables in Examples

[0169]

[0170] Comparative Example 1:

[0171] (1) Pretreatment of copper powder: Weigh 3 g of spherical copper powder with a particle size of 2.5 μm, add 50 ml of 10% by mass 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 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, and the mixture is reacted for 10 minutes after the addition is completed.

[0175] (5) After the reaction, the solution was filtered to obtain powder, which was washed three times with deionized water, and 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, with the last ultrasonic treatment lasting 5 minutes before washing again, and then washed three times with anhydrous ethanol, with the last ultrasonic treatment lasting 5 minutes before washing again.

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

[0178] Comparative Example 2:

[0179] (1) Pretreatment of copper powder: Weigh 3 g of spherical copper powder with a particle size of 2.5 μm, add 50 ml of 10% by mass 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, add 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, and the mixture is reacted for 10 minutes after the addition is completed.

[0183] (5) After the reaction, the solution was filtered to obtain powder, which was washed three times with deionized water, and 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, with the last ultrasonic treatment lasting 5 minutes before washing again, and then washed three times with anhydrous ethanol, with the last ultrasonic treatment lasting 5 minutes before washing again.

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

[0186] Coating rate performance test: The coating rate 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 coated. If the red area of ​​the ball exceeds half of the total area of ​​the ball, it is considered uncoated.

[0187] Table 2 Coverage data of some embodiments 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 of Examples 9 and 10 and Comparative Examples 1 and 2 shows that the coverage of the silver-coated copper powders obtained in Examples 9 and 10 is 95.13% and 93.58%, respectively, and the coverage of the silver-coated copper powders obtained in Comparative Examples 1 and 2 is 85.91% and 79.60%, respectively. Therefore, the coverage of the silver-coated copper powder obtained by treating with steel slag leaching solution is significantly higher than the coverage of the silver-coated copper powder obtained in the comparative example without using 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 leaching solution 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 concentration leads to poor dispersion effect, while too high concentration leads to system instability and increased costs.

[0192] The concentration of the reducing agent in the scheme 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 abnormally accelerated reaction rate to generate silver and increase costs.

[0193] The concentration of the complexing agent in the scheme of the present invention is preferably 0.01 mol / L-1 mol / L. Too low a concentration leads to poor complexing ability and easy generation of silver, while too high a concentration leads to too slow reaction rate and increased cost.

[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 dosage of silver nitrate in the scheme of the present invention is preferably 40%-100% of the mass of the copper powder. Too low a dosage will result in too little coating on the surface of the copper powder and poor antioxidant performance, while too high a dosage will result in the formation of silver alone.

[0196] The working principle of the above embodiment is: 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 steel slag enter the solution, and the copper powder is pickled with the acid leaching solution. While the oxide on the surface of the copper powder is removed by pickling, 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, wherein low-valent iron ions, vanadium ions, and manganese ions in the metal ions reduce silver ions and the obtained 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, and after adding silver nitrate solution, the silver ions are reduced, and the silver ions are deposited in situ on the surface of the copper powder, thereby improving the efficiency of reduction deposition, and copper and non-metallic elements as well as the above-mentioned metal ions can form a phosphating film with non-metallic elements such as phosphorus on the surface of the copper powder, which can wrap the uncoated area of ​​the silver element, and has an antioxidant effect. The reduction effect of the metal elements in 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 being oxidized, which has a synergistic effect on the anti-oxidation performance of the copper powder during the reaction process, so that the silver-coated copper powder prepared by the present invention has a higher coverage rate and silver content, good compactness and anti-oxidation performance, and better conductivity.

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

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

[0199] Although 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 the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing silver-coated copper powder using steel slag acid leaching solution, characterized in that: The following steps are involved: S1: mixing steel slag with acid, stirring and leaching, and filtering to obtain an acid leaching solution; S2: uniformly mixing the copper powder and 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, and then adding a silver nitrate solution to react. The reaction product is washed and dried to obtain a silver-coated copper powder.

2. The method for preparing silver-coated copper powder by using steel slag acid leaching solution according to claim 1, characterized in that: 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.

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

4. The method for preparing silver-coated copper powder by using steel slag acid leaching solution according to claim 1, characterized in that: 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%.

5. The method for preparing silver-coated copper powder by using steel slag acid leaching solution 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.

6. The method for preparing silver-coated copper powder using steel slag acid leaching solution 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.

7. The method for preparing silver-coated copper powder using steel slag acid leaching solution 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.

8. The method for preparing silver-coated copper powder using steel slag acid leaching solution 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.

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

Images