Brazing filler metal recovery method and quartz separating agent

Abstract

The invention provides a brazing filler metal recovery method and a quartz separating agent. According to the method, metal carbonate and boric anhydride serve as quartz separating agents, carbon dioxide is formed in the heating and melting process of the quartz separating agents and the brazing filler metal production waste, the metal carbonate is decomposed and reacts with boric anhydride and quartz sand, a low-oxygen-partial-pressure atmosphere is formed and covered with borate and silicate generated in the heating and melting process, and the low-oxygen-partial-pressure atmosphere is formed. The brazing filler metal can be prevented from being oxidized in the separation process of the brazing filler metal alloy and quartz, and the yield of the brazing filler metal alloy is close to 100%; meanwhile, the loss of the content of non-metal components in the brazing filler metal is also avoided; liquid vitreous body slag generated in the reaction can be used as a covering agent during brazing filler metal smelting, waste is recycled, materials are not wasted in the whole process, and no harmful substance is discharged; therefore, a heating melting method is adopted, the brazing filler metal alloy is melted out at a time, almost all the brazing filler metal alloy can be recycled to serve as foundry returns to be added into the alloy needing to be smelted next time, the recycling process is short, efficiency is high, and environment friendliness is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of welding, and particularly to a method for recycling solder and a quartz separating agent. Background Art

[0002] As one of the three major welding technologies, brazing technology is a welding technology that joins base metals together by filling the gaps between solid base metals with liquid solder and mutual diffusion. It is widely used in industries such as aerospace, automotive manufacturing, household appliances, and integrated circuits, and also faces the transformation of zero-carbon and low-carbon manufacturing.

[0003] The composition of brazing materials includes almost all metal elements such as silver, copper, zinc, nickel, manganese, iron, aluminum, magnesium, etc. and some non-metal elements such as hydrogen, carbon, nitrogen, silicon, boron, etc. Most brazing materials belong to non-ferrous metal materials, and they are formed into a solder ingot with uniform composition by melting one or more raw materials in an intermediate frequency furnace. During the heating and melting process, the utensils for holding the solder alloy are generally graphite crucibles. The graphite crucibles will crack due to quality problems, oxidation and burning during long-term use, etc. The solder alloy will penetrate into the quartz sand furnace lining around the graphite crucible along the cracks. The separation of the solder alloy from the quartz sand is a difficult problem that solder manufacturing enterprises have to face. There are many types of metal elements in the solder, and common ones include various alloy elements such as Ag / Cu / Zn / Ni / Sn / Al / Pd / Ti, etc. Usually, dilute nitric acid is used to dissolve the solder alloy, and then the quartz sand is filtered out, and the main metals are extracted from the solution through multiple chemical replacement or electrolysis methods. However, it is difficult to completely replace or electrolyze all the metal elements by this conventional method, and the process is complex and the metal recovery rate is low.

[0004] Facing this situation, establishing a resource-saving solder recycling circular economy model and realizing "low consumption, low emissions, and high efficiency" solder recycling is an urgent topic for the current development of new quality productivity in the brazing industry. Summary of the Invention

[0005] In view of this, the main purpose of the present invention is to provide a method for recycling solder with high metal alloy recovery efficiency, short process, and environmental protection.

[0006] Specifically, a method for recycling solder includes the steps: Pretreatment: First, completely cover the solder production waste with a quartz separating agent to obtain a mixed material; wherein, the solder production waste mainly includes quartz sand and solder alloy, and the solder alloy accounts for 30 - 90% of the mass of the solder production waste, and the quartz separating agent is mainly composed of metal carbonate and boric anhydride with a mass ratio of (80 - 92) : (8 - 20); Heating and melting: Heat the mixed material to a temperature 30°C - 50°C higher than the melting point of the filler metal and keep it warm, so that the alloy in the filler metal is converted into an alloy melt, and a liquid vitreous slag appears on the surface of the alloy melt. Stop heating until the area of the liquid vitreous slag no longer increases. Skimming the slag: Just skim the liquid vitreous slag from the surface of the alloy melt.

[0007] In the present invention, the "filler metal production waste" mainly refers to the unqualified filler metal waste containing quartz generated during the production and manufacturing of the filler metal alloy. The filler metal alloy therein includes at least one of silver-based filler metal alloy, copper-based filler metal alloy, nickel-based filler metal alloy, etc. That is, the filler metal production waste includes at least one of production waste silver-based filler metal, production waste copper-based filler metal, and production waste nickel-based filler metal.

[0008] The metal carbonate includes at least one of substances such as sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate that can decompose at high temperature to produce carbon dioxide.

[0009] Based on the above, the steps of the pretreatment include: first cutting the filler metal production waste into blocks not larger than 10 cm to obtain blocky filler metal production waste; placing the blocky filler metal production waste in a graphite crucible of an intermediate frequency furnace, and completely covering the blocky filler metal production waste with the quartz separating agent, where the mass of the quartz separating agent exceeds 10% of the mass of the filler metal production waste to obtain the mixed material; in this way, during the heating process, the quartz separating agent continuously adheres to quartz sand, the filler metal melts, and the separation of quartz sand from the liquid metal is achieved. The liquid vitreous slag can also prevent the filler metal from being oxidized during the heating process.

[0010] Based on the above, the steps of the heating and melting include: first heating the mixed material to 450°C to continuously melt boric anhydride; then heating to 500°C to decompose a part of the metal carbonate to form metal oxide and carbon dioxide gas; continuing to heat up to make the metal oxide react with boric anhydride and quartz sand respectively to form borate and silicate; when the temperature exceeds 720°C or during the process of 30°C - 50°C higher than the melting point of the filler metal, the metal carbonate reacts with quartz sand to produce silicate and carbon dioxide gas, and the quartz sand continuously reacts and dissolves; the alloy melt continuously seeps out from the quartz sand, and stop heating when stirring until the area of the crystal-clear liquid vitreous slag appearing on the surface of the alloy melt no longer increases. Because the density of the liquid vitreous slag is lower than that of the alloy melt, it can float on the surface of the alloy melt.

[0011] The main function of the metal carbonate in the quartz separating agent is to form carbon dioxide, which can generate a low oxygen pressure atmosphere. The formed metal oxide is the main component of borate and silicate. The main function of boric anhydride is to be an anti-oxidation covering agent and the main component of borate. To ensure the melting efficiency of quartz sand, the preferred mass ratio of metal carbonate to boric anhydride is (80 - 92) : (8 - 20), such as 80:20, 82:18, 85:15, 88:12, 90:10, 92:8, etc., and more preferably (85 - 90) : (10 - 15). In addition, the mass ratio of metal carbonate to boric anhydride is related to the proportion of the filler alloy in the waste materials of bulk filler production. When the proportion of the filler is relatively large and the proportion of quartz sand is relatively small, the dosage of metal carbonate is less, and the mass ratio of metal carbonate to boric anhydride is smaller. When the proportion of the filler is relatively small and the proportion of quartz sand is relatively large, more metal carbonate needs to be used, and the mass ratio of metal carbonate to boric anhydride is larger.

[0012] The reason for heating to a constant temperature after heating to 30°C - 50°C above the melting point of the filler during the heating and melting process is mainly that heating to 30°C - 50°C above the melting point of the filler can ensure that the alloy in the filler is in a liquid state, which is easy to separate from quartz sand, and it can prevent the evaporation or burning loss of alloy elements in the filler.

[0013] Based on the above, the steps of skimming the molten slag include: first, using a slag skimming tool to skim the liquid vitreous molten slag from the surface of the alloy melt, and then pouring the alloy melt into a mold to form a filler alloy ingot. In this way, it can be used as the return material for this filler. Since the molten slag is an inorganic salt vitreous body, it is easy to adhere to slag skimming tools made of materials such as graphite and ceramics when in a liquid state, so it is convenient to remove using a slag skimming tool.

[0014] Another object of the present invention is to provide a quartz separating agent for recovering the filler alloy in the waste materials of filler production, which mainly consists of metal carbonate and boric anhydride with a mass ratio of (80 - 92) : (8 - 20). Among them, the waste materials mainly include quartz sand and the filler alloy, and the filler alloy accounts for 30 - 90% of the mass of the waste materials of filler production.

[0015] During the heating and melting process of the quartz separating agent and the waste materials of filler production, carbon dioxide is formed during the decomposition of the metal carbonate and the reaction with boric anhydride and quartz sand, forming a low oxygen partial pressure atmosphere, and it is covered by the borate and silicate generated during the heating and melting process, which can prevent the oxidation of the filler alloy during the separation of the filler alloy from quartz. The recovery rate of the filler alloy is close to 100%. At the same time, it also avoids the loss of the content of non-metallic components in the filler. The liquid vitreous molten slag generated by the reaction can be used as a covering agent during the melting of the filler, realizing the recycling of waste materials. There is no waste in the whole process of materials and no harmful substance emissions.

[0016] Therefore, the above-mentioned solder recycling method provided by the present invention uses metal carbonate and boric anhydride as quartz separation agents, adopts the heating and melting method, and melts out the solder alloy at one time. The solder alloy can be almost completely recycled and added as remelting stock to the alloy to be melted next time. The recycling process is short, the efficiency is high, no chemical or electrolytic wastewater is generated, and it is environmentally friendly. Detailed implementation mode

[0017] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0018] In the ranges disclosed in the present invention, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in the present invention.

[0019] Unless otherwise specified, the terms used in the present invention are all common terms in the art. For the preparation processes, test methods, etc. used in each implementation mode that are not specifically described, they are all conventional means well-known to those skilled in the art, and the raw materials and equipment used can be obtained from public commercial channels.

[0020] Example 1 This example provides a BAg45CuZn solder recycling method, including the steps of: Using a shearing machine, 100 kg of solder production waste is cut into blocks with a size not greater than 10 cm. Among them, the solder production waste is composed of quartz sand and BAg45CuZn solder, and the proportion of BAg45CuZn solder is 50%; Put the above-mentioned block-shaped solder production waste into a graphite crucible of an intermediate frequency furnace, and completely cover the block-shaped solder production waste with 20 kg of quartz separation agent to obtain a mixed material; among them, the quartz separation agent is composed of soda ash and boric anhydride with a mass ratio of 90:10; Start the induction power supply and keep the temperature at 780 °C during induction heating. The following melting reaction process will occur in the middle: ① When the temperature rises to 450 °C, boric anhydride keeps melting; ② When the temperature rises to 500 °C, soda ash gradually decomposes to form sodium oxide and releases carbon dioxide at the same time; ③ As the temperature rises, sodium oxide reacts with boric anhydride to form sodium borate and reacts with quartz sand to form sodium silicate; ④ When the temperature exceeds 720 °C, sodium carbonate reacts with quartz sand to form sodium silicate and releases carbon dioxide at the same time. During this process, quartz sand keeps dissolving and the BAg45CuZn alloy melt continuously seeps out from the quartz sand. After the BAg45CuZn filler metal is completely melted, stop heating when stirring until the area of the crystal-clear liquid on the surface of the alloy melt no longer increases; Skim off the slag on the surface, pour the metal melt into a mold to form a 49.98 kg silver-based alloy ingot. Use chemical analysis method to detect that the composition of the silver-based alloy ingot includes Ag: 44.96%, Cu: 30.04% and Zn: 25.00%, which is basically the same as the composition of the BAg45CuZn filler metal and can be used as the return material for the BAg45CuZn filler metal. At the same time, the skimmed slag can also be used as a covering agent during the melting of the BAg45CuZn filler metal.

[0021] Example 2 This example provides a method for recycling BAg45CuZn filler metal, which is basically the same as the recycling method provided in Example 1. The main difference is that: the quartz separating agent is composed of soda ash and boric anhydride with a mass ratio of 80:20, and finally a 49.97 kg silver-based alloy ingot is obtained.

[0022] Example 3 This example provides a method for recycling BAg45CuZn filler metal, which is basically the same as the recycling method provided in Example 1. The main difference is that: the proportion of BAg45CuZn filler metal in the waste material for filler metal production is 30%, the quartz separating agent is composed of soda ash and boric anhydride with a mass ratio of 92:8, and finally a 29.98 kg silver-based alloy ingot is obtained.

[0023] Example 4 This example provides a method for recycling BAg45CuZn filler metal, which is basically the same as the recycling method provided in Example 1. The main difference is that: the proportion of BAg45CuZn filler metal in the waste material for filler metal production is 90%, the quartz separating agent is composed of soda ash and boric anhydride with a mass ratio of 82:18, and finally an 89.95 kg silver-based alloy ingot is obtained.

[0024] Example 5 This embodiment provides a method for recycling 100 kg of BCu62Zn filler metal, which is basically the same as the recycling method provided in Embodiment 1. The main differences are as follows: The proportion of the copper-based filler metal in the filler metal production waste is 60%. The quartz separating agent is composed of soda ash and boric anhydride with a mass ratio of 90:10. The heating temperature is 955 °C. Finally, 59.96 kg of copper-based alloy ingots are obtained. Chemical analysis is used to detect that the composition of the copper-based alloy ingots includes Cu: 61.96% and Zn: 38.04%, which is basically the same as the composition of the copper-based filler metal BCu62Zn. It can be used as the return material for the copper-based filler metal BCu62Zn. At the same time, the skimmed slag can also be used as a covering agent during the melting of the copper-based filler metal BCu62Zn.

[0025] Embodiment 6 This embodiment provides a method for recycling 100 kg of BNi89P filler metal, which is basically the same as the recycling method provided in Embodiment 1. The main differences are as follows: The proportion of the nickel-based filler metal in the filler metal production waste is 50%. The quartz separating agent is composed of soda ash and boric anhydride with a mass ratio of 90:10. The temperature is heated to 910 °C. Finally, 49.94 kg of nickel-based alloy ingots are obtained. ICP detection method is used to detect that the composition of the nickel-based alloy ingots includes Ni: 88.92% and P: 11.08%, which is basically the same as the composition of the nickel-based filler metal BNi89P. It can be used as the return material for the nickel-based filler metal BNi89P. At the same time, the skimmed slag can also be used as a covering agent during the melting of the nickel-based filler metal BNi89P.

[0026] Embodiment 7 This embodiment provides a method for recycling BAg30CuZn filler metal, which is basically the same as the recycling method provided in Embodiment 1. The main differences are as follows: The proportion of the silver-based filler metal in the filler metal production waste is 40%. The quartz separating agent is composed of sodium bicarbonate and boric anhydride with a mass ratio of 85:15. Sodium bicarbonate begins to decompose into sodium carbonate and carbon dioxide gas at 50 °C and completely decomposes into sodium carbonate at 270 °C. The subsequent heating and melting process is the same as that in Embodiment 1, and the heating temperature is 800 °C. Finally, 39.91 kg of silver-based alloy ingots are obtained. Chemical analysis is used to detect that the composition of the silver-based alloy ingots includes: Ag: 29.92, Cu: 38.08 and Zn: 32.00%, which is basically the same as the composition of the silver-based filler metal BAg30CuZn. It can be used as the return material for the silver-based filler metal BAg30CuZn. At the same time, the skimmed slag can also be used as a covering agent during the melting of the silver-based filler metal BAg30CuZn.

[0027] Embodiment 8 This embodiment provides a method for recycling BCu58ZnMn filler metal, which is basically the same as the recycling method provided in Embodiment 7. The main difference lies in that: the proportion of the copper-based filler metal in the filler metal production waste is 40%, the quartz separating agent is composed of sodium bicarbonate and boric anhydride with a mass ratio of 80:20, and finally 39.90 kg of copper-based alloy ingots are obtained. Chemical analysis is used to detect that the components of the copper-based alloy ingots include Cu: 58.05%, Zn: 38.05%, and Mn: 3.90%, which are basically the same as the composition of the copper-based filler metal BCu58ZnMn. It can be used as the remelting stock for the copper-based filler metal BCu58ZnMn. At the same time, the skimmed slag can also be used as the covering agent during the melting of the copper-based filler metal BCu58ZnMn.

[0028] Embodiment 9 This embodiment provides a method for recycling BNi92SiB filler metal, which is basically the same as the recycling method provided in Embodiment 1. The main difference lies in that: the proportion of the copper-based filler metal in the filler metal production waste is 40%, the quartz separating agent is composed of sodium bicarbonate and boric anhydride with a mass ratio of 80:20, the heating temperature is 1080 °C, and finally 39.93 kg of nickel-based alloy ingots are obtained. ICP detection method is used to detect that the components of the nickel-based alloy ingots include Ni: 92.45%, Si: 4.50%, B: 3.05%, which are basically the same as the composition of the nickel-based filler metal BNi92SiB. It can be used as the remelting stock for the nickel-based filler metal BNi92SiB. At the same time, the skimmed slag can also be used as the covering agent during the melting of the nickel-based filler metal BNi92SiB.

[0029] Comparative Example Comparative Example 1 provides a method for recycling BAg45CuZn filler metal, which is basically the same as the recycling method provided in Embodiment 1. The main difference lies in that: the quartz separating agent is composed of soda ash and boric anhydride with a mass ratio of 75:25, and finally 38.46 kg of silver-based alloy ingots are obtained.

[0030] Comparative Example 2 provides a method for recycling BAg45CuZn filler metal, which is basically the same as the recycling method provided in Embodiment 1. The main difference lies in that: the quartz separating agent is composed of soda ash and boric anhydride with a mass ratio of 95:5, and finally 37.81 kg of silver-based alloy ingots are obtained.

[0031] It can be seen that the filler metal recycling method provided in the embodiments of the present invention combines the heating melting method to melt out the filler metal alloy at one time. The filler metal alloy can be almost completely recycled and added as the remelting stock to the alloy to be melted next time. Moreover, the slag generated during the recycling process can also be used as the covering agent for filler metal melting. The recycling process is short, the efficiency is high, there is no chemical or electrolytic wastewater generated, and it is environmentally friendly.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: it is still possible to modify the specific implementation manners of the present invention or perform equivalent replacements for some technical features; without departing from the spirit of the technical solutions of the present invention, they should all be covered within the scope of the technical solutions claimed by the present invention.

Claims

1. A method for recycling filler metal, comprising the steps of: Pretreatment: First, completely cover the waste materials from solder production with a quartz separating agent to obtain a mixed material; among them, The filler metal production waste mainly includes quartz sand and filler metal alloy, and the filler metal alloy accounts for 30 - 90% of the mass of the filler metal production waste. The quartz separating agent is mainly composed of metal carbonate and boric anhydride with a mass ratio of (80 - 92) : (8 - 20); Heating and melting: Heat the mixed material to a temperature 30°C - 50°C higher than the melting point of the filler metal and keep it warm, so that the alloy in the filler metal is converted into an alloy melt, and a liquid vitreous slag appears on the surface of the alloy melt. Stop heating until the area of the liquid vitreous slag no longer increases; Skimming the slag: Skim the liquid vitreous slag from the surface of the alloy melt.

2. The solder recovery method according to claim 1, wherein The filler metal alloy includes a silver-based filler metal alloy, a copper-based filler metal alloy or a nickel-based filler metal alloy.

3. The solder recovery method according to claim 1, characterized in that, The metal carbonate includes at least one of sodium carbonate, sodium bicarbonate, potassium carbonate and potassium bicarbonate.

4. The solder recovery method according to claim 1, wherein The steps of the pretreatment include: First, cut the filler metal production waste into blocks not larger than 10 cm to obtain block-shaped filler metal production waste; Place the block-shaped filler metal production waste in a graphite crucible of an intermediate frequency furnace, and completely cover the block-shaped filler metal production waste with the quartz separating agent. The mass of the quartz separating agent exceeds 10% of the mass of the filler metal production waste to obtain the mixed material.

5. The solder recovery method according to any one of claims 1-4, characterized in that, The steps of the heating and melting include: First, heat the mixed material to 450°C to continuously melt the boric anhydride; Then heat to 500°C to decompose a part of the metal carbonate to form metal oxide and carbon dioxide gas; Continue to heat up to make the metal oxide react with boric anhydride and quartz sand respectively to form borate and silicate; When the temperature exceeds 720°C or during the process of 30°C - 50°C higher than the melting point of the filler metal, the metal carbonate reacts with quartz sand to produce silicate and carbon dioxide gas, and the quartz sand continuously reacts and dissolves; The alloy melt continuously seeps out from the quartz sand, and stop heating when the area of the crystal-clear liquid vitreous slag appearing on the surface of the alloy melt no longer increases.

6. The solder recovery method according to claim 5, characterized in that, The steps of skimming the slag include: First, use a slag skimming tool to skim the liquid vitreous slag from the surface of the alloy melt, and then pour the alloy melt into a mold to form a filler metal alloy ingot.

7. A quartz separating agent, characterized in that, Used for recycling the filler metal alloy in the filler metal production waste, mainly composed of metal carbonate and boric anhydride with a mass ratio of (80 - 92) : (8 - 20).

8. The quartz separating agent according to claim 7, wherein The metal carbonate includes at least one of sodium carbonate, sodium bicarbonate, potassium carbonate and potassium bicarbonate.

9. The quartz separating agent according to claim 7 or 8, characterized in that, The filler metal production waste mainly includes quartz sand and the filler metal alloy, and the filler metal alloy accounts for 30 - 90% of the mass of the filler metal production waste.

10. The quartz separating agent according to claim 9, characterized in that, The filler metal alloy includes a silver-based filler metal alloy, a copper-based filler metal alloy or a nickel-based filler metal alloy.