High-purity target material preparation process based on gold waste

Abstract

The invention relates to a high-purity target material preparation process based on gold waste, and belongs to the technical field of target material preparation. By optimizing purification steps and process parameters, efficient purification of the gold waste is achieved, meanwhile, vacuum melting process parameters are regulated and controlled, energy consumption and emission of harmful substances are reduced, and the concept of sustainable development is met. Preferably, a mixed solution of dibutyl carbitol and sec-octanol is used as an extraction agent, so that the gold purification efficiency and selectivity are remarkably improved, and accurate separation of the gold from the waste is ensured. A two-section smelting technology is combined with reasonable setting of annealing parameters, and the gold target material which is uniform in component, high in mechanical strength and excellent in performance is prepared. According to the method, resource utilization of the gold waste is achieved, the environmental load is reduced, and the prepared target material meets the high-performance application requirement and has remarkable economic and environmental benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of target material preparation, and relates to a high-purity target material preparation process based on gold waste. Background Art

[0002] With the rapid development of high-tech industries such as microelectronics, optoelectronics and solar cells, higher and higher requirements are placed on the purity and performance of target materials. As an indispensable key material in these fields, the purity, uniformity and stability of gold target materials directly affect the performance and quality of the final product.

[0003] At present, most target materials are directly processed from high-purity metal raw materials, which requires extremely high purity of the raw materials, resulting in higher production costs and serious resource consumption problems.

[0004] The scraps generated during the processing of precious metals such as gold are increasing day by day. These scraps are often regarded as waste or low-value materials due to their irregular shapes and sizes. Their treatment and reuse have become an urgent problem to be solved. In fact, gold scrap still contains a large amount of precious metal components and has a high reuse value. Therefore, it is particularly necessary to develop a technology for preparing sputtering targets using gold scrap. Summary of the invention

[0005] The purpose of the present invention is to provide a high-purity target material preparation process based on gold waste, which ensures the high purity, uniformity and excellent physical properties of the target material through fine recovery and purification of gold waste, two-stage vacuum melting process and strict post-processing steps. This process can not only realize the efficient recovery and reuse of gold waste, reduce resource waste and environmental pollution, but also significantly reduce the production cost of sputtering targets and improve economic benefits.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A high-purity target material preparation process based on gold waste, the specific steps of the high-purity target material preparation process are as follows: S1: The recovered gold waste is sorted to remove large particles of impurities, and then placed in a ball mill for ball milling at a speed of 350 r / min for 30 min to obtain gold waste of uniform size; S2: Place the gold waste in a cleaning solution that completely covers the gold waste. At the same time, introduce ultrasonic vibration with a vibration frequency of 5 kHz and an ultrasonic time of 30 min. Then, use deionized water to repeatedly clean the gold waste and place it in a vacuum drying oven for drying at a temperature of 60 °C for 12 h. S3: The dried gold waste was placed in a strong acid mixture, ultrasonically dissolved at 80 °C for 1 h, and stirred at a speed of 500 r / min to obtain solution A; S4: Mix solution A with the extractant, adjust the pH of the mixture to 4-5, and introduce high-purity argon into the mixture. Stir well at 60 °C for 30 min, then let stand for 1 h, separate the two phases using a separatory funnel, and further purify the organic phase using a detergent to obtain an organic phase B. S5: The organic phase B is heated to 85 °C and high-purity argon is introduced, and the oxalic acid solution is added, stirred for 2.5 h, separated by a high-speed centrifuge at a speed of 5000 r / min and a centrifugal time of 10 min, the precipitate is washed with deionized water, and dried in a vacuum drying oven at a drying temperature of 60 °C and a drying time of 12 h to obtain a smelting raw material; S6: placing the smelting raw materials in a graphite crucible and placing the crucible in a vacuum melting furnace, evacuating the furnace to a vacuum, using medium frequency induction heating, the melting time is 1 h, the melting temperature is 1000-1100 °C, and a propeller stirrer is turned on during melting to stir the melt at a stirring speed of 800 r / min, and a gold ingot is obtained after rapid pouring; S7: placing the obtained gold ingot in a vacuum melting furnace for secondary melting, wherein the secondary melting time is 1.5 hours, the secondary melting temperature is 1150-1200°C, the stirring speed is 1000 r / min, the annealing condition is 800°C for 5-6 hours, and then slowly cooling to room temperature to obtain a gold slab embryo; S8: Mechanically process and surface polish the gold plate blank to obtain the high-purity target material.

[0007] Furthermore, the cleaning solution in S2 is a mixed solution of sodium dodecyl sulfate, sodium bicarbonate, ethanol and deionized water, wherein the mass ratio of sodium dodecyl sulfate, sodium bicarbonate, ethanol and deionized water is 2:1:3:3.

[0008] Furthermore, the strong acid mixture in S3 is a mixture of concentrated nitric acid and concentrated hydrochloric acid.

[0009] Furthermore, the extractant in S4 is a mixture of dibutyl carbitol and octanol, wherein the volume ratio of dibutyl carbitol to octanol is 1:(2-4).

[0010] Furthermore, the solution A and the extractant in S4 are mixed in a volume ratio of 1:2.

[0011] Furthermore, the detergent in S4 is 0.2 M hydrochloric acid solution.

[0012] Furthermore, the concentration of the oxalic acid solution in S5 is 0.5 M.

[0013] Furthermore, the vacuuming method in S6 is to first start the mechanical pump to pump the furnace to a low vacuum, at which point the vacuum is about 10 -2 Pa, and then start the molecular pump to pump the furnace to high vacuum, at this time the vacuum degree is ≤10 -5 Pa.

[0014] Furthermore, argon is introduced as a protective gas in the S7 annealing condition.

[0015] By selecting a mixed solution of dibutyl carbitol and 2-octanol as an extractant and adjusting the ratio thereof, it has excellent gold purification performance. As an efficient gold extractant, dibutyl carbitol can quantitatively and selectively extract gold from a hydrochloric acid solution, separate it from other metal elements, and has high extraction efficiency; while 2-octanol is prone to generate unstable ion association complexes when extracting gold and transfers to an organic phase, with obvious gold extraction effect and large gold extraction capacity. Dibutyl carbitol and 2-octanol can exert a better synergistic effect under the condition of a certain volume ratio, thereby making the extraction efficiency high and the volume large. In addition, high-purity argon gas is introduced during the extraction and back-extraction processes to remove oxygen and other impurity gases in the mixed solution that may interfere with the reaction process, ensure the purity of the reaction environment, and ensure the purity of the extracted product.

[0016] A gold target with uniform composition and high mechanical strength is obtained through a two-stage smelting process. The vacuum melting furnace adopts medium-frequency induction heating. By adjusting the current frequency and power, the melt is heated quickly and evenly to avoid the generation of impurities caused by local overheating. The agitator is designed as a propeller type, made of high-temperature resistant alloy. It is driven by a precision motor to perform three-dimensional stirring in the melt to ensure that the gold melt is fully mixed and evenly distributed during the smelting process. In the first smelting process, the gold raw materials are initially melted and mixed. Through the high temperature environment of smelting, impurities with low melting points are evaporated or oxidized to improve the purity of gold, but there may still be problems with uneven gold distribution at this time. The second smelting is to heat and refine the gold after the initial smelting again. Through more sufficient stirring and mixing, the composition and organization distribution in the gold are more uniform, reducing internal segregation and performance differences. Through appropriate holding time and slow cooling rate, a gold slab with smaller grains is obtained, and the density of the slab structure is effectively improved, so that the prepared target material has better mechanical properties. In addition, the annealing treatment is carried out under argon protection throughout the process to avoid oxidation or contamination of the slab during the annealing process, thereby ensuring the quality and performance of the gold target.

[0017] Beneficial effects of the present invention: (1) The present invention uses gold waste as the raw material of the target material, realizes the resource recovery and reuse of gold waste, reduces the waste of rare precious metal resources, and conforms to the concept of sustainable development. By optimizing and regulating the gold waste purification steps, efficient heating and fine control of process parameters, the energy consumption in the overall process is reduced and the emission of harmful gases is reduced, effectively reducing the environmental load in the production process.

[0018] (2) By selecting and preparing a mixed solution of dibutyl carbitol and 2-octanol as the extraction agent, the efficiency and selectivity of gold purification were significantly enhanced. Dibutyl carbitol can accurately extract gold from the hydrochloric acid solution with its high efficiency and achieve effective separation from other metal elements; 2-octanol further improves the overall purification efficiency with its large gold extraction capacity and obvious gold extraction effect. The synergistic effect of the two ensures the efficiency and precision of the extraction process.

[0019] (3) A two-stage smelting process is used to ensure the performance and quality of the gold target. The initial smelting further removes impurities and ensures the purity of the target; the secondary smelting makes the composition and organization of gold more uniform, reduces internal segregation, and enhances the mechanical strength of the target. In addition, heat preservation and slow cooling promote the formation of fine grains, improve the density of the slab, and enhance the overall performance of the target. With the combined effect of a series of measures, the prepared gold target has uniform composition and high mechanical strength, meeting the needs of high-performance applications. DETAILED DESCRIPTION

[0020] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0021] Example 1 S1: The recovered gold waste is sorted to remove large particles of impurities, and then placed in a ball mill for ball milling at a speed of 350 r / min for 30 min to obtain gold waste of uniform size; S2: Place the gold waste in a cleaning solution, which is a mixed solution of sodium dodecyl sulfate, sodium bicarbonate, ethanol and deionized water, wherein the mass ratio of sodium dodecyl sulfate, sodium bicarbonate, ethanol and deionized water is 2:1:3:3. The cleaning solution needs to completely cover the gold waste. At the same time, ultrasonic vibration is introduced with a vibration frequency of 5 kHz and an ultrasonic time of 30 min. The gold waste is then repeatedly cleaned with deionized water and placed in a vacuum drying oven for drying at a temperature of 60 °C for 12 h. S3: The dried gold waste was placed in a solution of concentrated hydrochloric acid and concentrated nitric acid in a mass ratio of 1:3, dissolved by ultrasonic at 80°C for 1 h, and stirred at a speed of 500 r / min to obtain solution A; S4: Solution A was mixed with an extractant at a volume ratio of 1:2, wherein the extractant was a solution of dibutyl carbitol and 2-octanol mixed at a volume ratio of 1:3, the pH of the mixed solution was adjusted to 4, and high-purity argon was introduced into the mixed solution, and the mixture was fully stirred at 60 °C for 30 min, and then allowed to stand for 1 h, and the two phases were separated using a separatory funnel, and the organic phase was further purified using a 0.2 M hydrochloric acid solution as a detergent to obtain an organic phase B; S5: The organic phase B is heated to 85 °C and high-purity argon is introduced, 0.5 M oxalic acid solution is added, stirred for 2.5 h, separated by a high-speed centrifuge at a speed of 5000 r / min for 10 min, the precipitate is washed with deionized water, and dried in a vacuum drying oven at a drying temperature of 60 °C for 12 h to obtain a smelting raw material; S6: Place the smelting raw materials in a graphite crucible and place the crucible in a vacuum melting furnace. Start the mechanical pump to pump the furnace to a low vacuum. At this time, the vacuum degree is about 10 -2 Pa, and then start the molecular pump to pump the furnace to high vacuum, at this time the vacuum degree is ≤10 -5 Pa, medium frequency induction heating was used, the melting time was 1 h, the melting temperature was 1000 °C, a propeller stirrer was turned on to stir the melt during melting, the stirring speed was 800 r / min, and a gold ingot was obtained after rapid pouring; S7: placing the obtained gold ingot in a vacuum melting furnace for secondary melting, wherein the secondary melting time is 1.5 hours, the secondary melting temperature is 1150°C, the stirring speed is 1000 r / min, and the annealing condition is argon as a protective gas at 800°C for 6 hours, and then slowly cooling to room temperature to obtain a gold plate embryo; S8: Mechanically process and surface polish the gold plate blank to obtain the high-purity target material.

[0022] Example 2 S1: The recovered gold waste is sorted to remove large particles of impurities, and then placed in a ball mill for ball milling at a speed of 350 r / min for 30 min to obtain gold waste of uniform size; S2: Place the gold waste in a cleaning solution, which is a mixed solution of sodium dodecyl sulfate, sodium bicarbonate, ethanol and deionized water, wherein the mass ratio of sodium dodecyl sulfate, sodium bicarbonate, ethanol and deionized water is 2:1:3:3. The cleaning solution needs to completely cover the gold waste. At the same time, ultrasonic vibration is introduced with a vibration frequency of 5 kHz and an ultrasonic time of 30 min. The gold waste is then repeatedly cleaned with deionized water and placed in a vacuum drying oven for drying at a temperature of 60 °C for 12 h. S3: The dried gold waste was placed in a solution of concentrated hydrochloric acid and concentrated nitric acid in a mass ratio of 1:3, dissolved by ultrasonic at 80°C for 1 h, and stirred at a speed of 500 r / min to obtain solution A; S4: Solution A was mixed with an extractant at a volume ratio of 1:2, wherein the extractant was a solution of dibutyl carbitol and 2-octanol mixed at a volume ratio of 1:2, the pH of the mixed solution was adjusted to 4.5, and high-purity argon gas was introduced into the mixed solution, and the mixture was fully stirred at 60 °C for 30 min, and then allowed to stand for 1 h, and the two phases were separated using a separatory funnel, and the organic phase was further purified using a 0.2 M hydrochloric acid solution as a detergent to obtain an organic phase B; S5: The organic phase B is heated to 85 °C and high-purity argon is introduced, 0.5 M oxalic acid solution is added, stirred for 2.5 h, separated by a high-speed centrifuge at a speed of 5000 r / min for 10 min, the precipitate is washed with deionized water, and dried in a vacuum drying oven at a drying temperature of 60 °C for 12 h to obtain a smelting raw material; S6: Place the smelting raw materials in a graphite crucible and place the crucible in a vacuum melting furnace. Start the mechanical pump to pump the furnace to a low vacuum. At this time, the vacuum degree is about 10 -2 Pa, and then start the molecular pump to pump the furnace to high vacuum, at this time the vacuum degree is ≤10 -5 Pa, medium frequency induction heating was used, the melting time was 1 h, the melting temperature was 1050 °C, a propeller stirrer was turned on to stir the melt during melting, the stirring speed was 800 r / min, and a gold ingot was obtained after rapid pouring; S7: placing the obtained gold ingot in a vacuum melting furnace for secondary melting, wherein the secondary melting time is 1.5 hours, the secondary melting temperature is 1170°C, the stirring speed is 1000 r / min, and the annealing condition is argon as a protective gas at 800°C for 5.5 hours, and then slowly cooling to room temperature to obtain a gold plate embryo; S8: Mechanically process and surface polish the gold plate blank to obtain the high-purity target material.

[0023] Example 3 S1: The recovered gold waste is sorted to remove large particles of impurities, and then placed in a ball mill for ball milling at a speed of 350 r / min for 30 min to obtain gold waste of uniform size; S2: Place the gold waste in a cleaning solution, which is a mixed solution of sodium dodecyl sulfate, sodium bicarbonate, ethanol and deionized water, wherein the mass ratio of sodium dodecyl sulfate, sodium bicarbonate, ethanol and deionized water is 2:1:3:3. The cleaning solution needs to completely cover the gold waste. At the same time, ultrasonic vibration is introduced with a vibration frequency of 5 kHz and an ultrasonic time of 30 min. The gold waste is then repeatedly cleaned with deionized water and placed in a vacuum drying oven for drying at a temperature of 60 °C for 12 h. S3: The dried gold waste was placed in a solution of concentrated hydrochloric acid and concentrated nitric acid in a mass ratio of 1:3, dissolved by ultrasonic at 80°C for 1 h, and stirred at a speed of 500 r / min to obtain solution A; S4: Solution A was mixed with an extractant at a volume ratio of 1:2, wherein the extractant was a solution of dibutyl carbitol and 2-octanol mixed at a volume ratio of 1:4, the pH of the mixed solution was adjusted to 5, and high-purity argon gas was introduced into the mixed solution, and the mixture was fully stirred at 60 °C for 30 min, and then allowed to stand for 1 h, and the two phases were separated using a separatory funnel, and the organic phase was further purified using a 0.2 M hydrochloric acid solution as a detergent to obtain an organic phase B; S5: The organic phase B is heated to 85 °C and high-purity argon is introduced, 0.5 M oxalic acid solution is added, stirred for 2.5 h, separated by a high-speed centrifuge at a speed of 5000 r / min for 10 min, the precipitate is washed with deionized water, and dried in a vacuum drying oven at a drying temperature of 60 °C for 12 h to obtain a smelting raw material; S6: Place the smelting raw materials in a graphite crucible and place the crucible in a vacuum melting furnace. Start the mechanical pump to pump the furnace to a low vacuum. At this time, the vacuum degree is about 10 -2 Pa, and then start the molecular pump to pump the furnace to high vacuum, at this time the vacuum degree is ≤10 -5 Pa, medium frequency induction heating was used, the melting time was 1 h, the melting temperature was 1100 °C, a propeller stirrer was turned on to stir the melt during melting, the stirring speed was 800 r / min, and a gold ingot was obtained after rapid pouring; S7: placing the obtained gold ingot in a vacuum melting furnace for secondary melting, wherein the secondary melting time is 1.5 hours, the secondary melting temperature is 1200°C, the stirring speed is 1000 r / min, and the annealing condition is argon as a protective gas at 800°C for 5 hours, and then slowly cooling to room temperature to obtain a gold plate embryo; S8: Mechanically process and surface polish the gold plate blank to obtain the high-purity target material.

[0024] Comparative Example 1 In this comparative example, the extractant is dibutyl carbitol, and the remaining steps are consistent with Example 1.

[0025] Comparative Example 2 In this comparative example, the extractant is octanol, and the remaining steps are consistent with those in Example 1.

[0026] Comparative Example 3 In this comparative example, only one smelting process is performed, and the remaining steps are consistent with those in Example 1.

[0027] The mass m1 of the gold waste and the mass m2 of the manufactured high-purity target in the embodiment and the comparative example were measured respectively, and the recovery rate was calculated, that is, the recovery rate = m2 / m1×100%.

[0028] The Au contents of the embodiments and comparative examples were measured using an inductively coupled plasma mass spectrometer.

[0029] The density of the high-purity target materials of the embodiment and the comparative example was measured respectively. The measurement steps were as follows: the actual density of the high-purity target materials of the embodiment and the comparative example was measured at 20°C and one atmosphere by using the Archimedean displacement method, and the ratio of the actual density to the theoretical density was calculated, that is, density = actual density / theoretical density × 100%.

[0030] The experimental results are summarized in the following table:

[0031] It can be seen from the experimental data that the mixed extractant preferably prepared in the present invention not only ensures the highest waste recycling rate at an appropriate ratio, but also ensures that the purity of the prepared gold target meets the use requirements. By optimizing the smelting process and adding a secondary refining step, a gold target with higher density and better quality is obtained.

[0032] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A process for preparing high-purity target materials based on gold waste, characterized in that: The specific steps of the high-purity target material preparation process are as follows: S1: The recovered gold waste is sorted to remove large particles of impurities, and then placed in a ball mill for ball milling at a speed of 350 r / min for 30 min to obtain gold waste of uniform size; S2: Place the gold waste in a cleaning solution that completely covers the gold waste. At the same time, introduce ultrasonic vibration with a vibration frequency of 5 kHz and an ultrasonic time of 30 min. Then, use deionized water to repeatedly clean the gold waste and place it in a vacuum drying oven for drying at a temperature of 60 °C for 12 h. S3: The dried gold waste was placed in a strong acid mixture, ultrasonically dissolved at 80 °C for 1 h, and stirred at a speed of 500 r / min to obtain solution A; S4: Mix solution A with the extractant, adjust the pH of the mixed solution to 4-5, and introduce high-purity argon gas into the mixed solution. Stir the mixture at 60°C for 30 min, then let it stand for 1 h, separate the two phases using a separatory funnel, and further purify the organic phase using a detergent to obtain an organic phase B. S5: The organic phase B is heated to 85 °C and high-purity argon is introduced, and the oxalic acid solution is added, stirred for 2.5 h, separated by a high-speed centrifuge at a speed of 5000 r / min and a centrifugal time of 10 min, the precipitate is washed with deionized water, and dried in a vacuum drying oven at a drying temperature of 60 °C and a drying time of 12 h to obtain a smelting raw material; S6: placing the smelting raw materials in a graphite crucible and placing the crucible in a vacuum melting furnace, evacuating the furnace, using medium frequency induction heating, the melting time is 1 h, the melting temperature is 1000-1100 °C, and a propeller stirrer is turned on during melting to stir the melt at a stirring speed of 800 r / min, and a gold ingot is obtained after rapid pouring; S7: placing the obtained gold ingot in a vacuum melting furnace for secondary melting, wherein the secondary melting time is 1.5 h, the secondary melting temperature is 1150-1200 °C, the stirring speed is 1000 r / min, the annealing condition is 800 °C for 5-6 h, and then slowly cooling to room temperature to obtain a gold plate embryo; S8: Mechanically process and surface polish the gold plate blank to obtain the high-purity target material.

2. A process for preparing a high-purity target material based on gold waste according to claim 1, characterized in that: The cleaning solution in S2 is a mixed solution of sodium dodecyl sulfate, sodium bicarbonate, ethanol and deionized water, wherein the mass ratio of sodium dodecyl sulfate, sodium bicarbonate, ethanol and deionized water is 2:1:3:

3.

3. The high-purity target material preparation process based on gold waste according to claim 1, characterized in that: The strong acid mixture in S3 is a mixture of concentrated nitric acid and concentrated hydrochloric acid.

4. The high-purity target material preparation process based on gold waste according to claim 1, characterized in that: The extractant in S4 is a mixture of dibutyl carbitol and octanol, wherein the volume ratio of dibutyl carbitol to octanol is 1:(2-4).

5. The process for preparing a high-purity target material based on gold waste according to claim 1, characterized in that: The solution A and the extractant in S4 are mixed in a volume ratio of 1:

2.

6. The process for preparing a high-purity target material based on gold waste according to claim 1, characterized in that: The detergent in S4 is 0.2 M hydrochloric acid solution.

7. The process for preparing a high-purity target material based on gold waste according to claim 1, characterized in that: The concentration of the oxalic acid solution in S5 is 0.5 M.

8. The process for preparing a high-purity target material based on gold waste according to claim 1, characterized in that: The method of evacuating the furnace in S6 is to start the mechanical pump to evacuate the furnace to a low vacuum. At this time, the vacuum degree is about 10 -2 Pa, and then start the molecular pump to pump the furnace to high vacuum, at this time the vacuum degree is ≤10 -5 Pa.

9. The process for preparing a high-purity target material based on gold waste according to claim 1, characterized in that: Argon is introduced as a protective gas in the S7 annealing condition.

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