A process for producing high purity target material based on gold scrap

Abstract

The application relates to a high-purity target material preparation process based on gold waste, and belongs to the technical field of target material preparation. Through optimization of a purification step and process parameters, efficient purification of gold waste is realized, meanwhile, vacuum smelting process parameters are regulated, energy consumption and emission of harmful substances are reduced, and the concept of sustainable development is met. A mixed solution of dibutyl carbitol and secondary octanol is preferably used as an extractant, which significantly improves the gold purification efficiency and selectivity, and ensures accurate separation of gold from the waste. Through two-stage smelting technology and reasonable setting of annealing parameters, gold target material with uniform composition, high mechanical strength and excellent performance is prepared. The application not only realizes resource utilization of gold waste, but also reduces environmental load, and the prepared target material meets the high-performance application requirement, and has remarkable economic and environmental benefits.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of target material preparation and relates to a high-purity target material preparation process based on gold scrap. BACKGROUND

[0002] With the rapid development of high-tech industries such as microelectronics, optoelectronics and solar cells, higher and higher requirements are put forward for the purity and performance of target materials. The purity, uniformity and stability of gold target material, which is an indispensable key material in these fields, 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 high production cost and serious resource consumption problems.

[0004] The scrap produced in the processing of gold and other precious metals is increasing, and these scrap materials are often regarded as waste or low-value materials due to their irregular shape and size, and their treatment and reuse have become a problem to be solved. In fact, gold scrap still contains a large amount of precious metal components and has high reuse value. Therefore, it is particularly necessary to develop a technology for preparing sputtering targets from gold scrap. SUMMARY

[0005] The purpose of the present application is to provide a high-purity target material preparation process based on gold scrap, which ensures high purity, uniformity and excellent physical properties of the target material through fine recovery and purification of gold scrap, two-stage vacuum melting process and strict post-treatment steps. The process not only realizes efficient recovery and reuse of gold scrap, reduces resource waste and environmental pollution, but also significantly reduces the production cost of sputtering targets and improves economic efficiency.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] A high-purity target material preparation process based on gold scrap, the specific steps of the high-purity target material preparation process are as follows:

[0008] S1: The recovered gold scrap is subjected to sorting treatment to remove large-particle impurities, and then is placed in a ball mill for ball milling at a speed of 350 r / min for 30 min to obtain gold scrap with uniform size;

[0009] S2: The gold scrap is placed in a cleaning solution which needs to completely cover the gold scrap, and an ultrasonic vibration is introduced, with a vibration frequency of 5 kHz and an ultrasonic time of 30 min. The gold scrap is repeatedly cleaned with deionized water and dried in a vacuum drying oven at a temperature of 60 ℃ for 12 h;

[0010] S3: placing the dried gold scrap into a strong acid mixture, ultrasonically dissolving for 1 h at 80 DEG C with stirring at 500 r / min to obtain solution A;

[0011] S4: mixing solution A with an extractant, adjusting the pH of the mixture to 4-5, bubbling high-purity argon into the mixture, fully stirring for 30 min at 60 DEG C, then standing for 1 h, separating the two phases using a separatory funnel, and further purifying the organic phase using a detergent to obtain organic phase B;

[0012] S5: heating organic phase B to 85 DEG C, bubbling high-purity argon into it, adding oxalic acid solution, stirring for 2.5 h, separating using a high-speed centrifuge at 5000 r / min for 10 min, washing the precipitate with deionized water, and drying in a vacuum drying oven at 60 DEG C for 12 h to obtain smelting raw material;

[0013] S6: placing the smelting raw material into a graphite crucible and placing the crucible in a vacuum smelting furnace, evacuating the furnace to vacuum, using a medium-frequency induction heating method, smelting for 1 h at 1000-1100 DEG C, and stirring the melt using a propeller stirrer at 800 r / min to obtain a gold ingot after rapid casting;

[0014] S7: placing the obtained gold ingot into a vacuum smelting furnace for secondary smelting, the secondary smelting being performed for 1.5 h at 1150-1200 DEG C with a stirring speed of 1000 r / min, and the annealing conditions being 800 DEG C for 5-6 h followed by slow cooling to room temperature to obtain a gold plate blank;

[0015] S8: mechanically processing and surface polishing the gold plate blank to obtain the high-purity target material.

[0016] Further, the cleaning solution in S2 is a mixed solution of sodium dodecyl sulfonate, sodium bicarbonate, ethanol, and deionized water, and the mass ratio of sodium dodecyl sulfonate, sodium bicarbonate, ethanol, and deionized water is 2:1:3:3.

[0017] Further, the strong acid mixture in S3 is a mixture of concentrated nitric acid and concentrated hydrochloric acid.

[0018] Further, the extractant in S4 is a mixture of dibutyl carbitol and secondary octanol, and the volume ratio of dibutyl carbitol to secondary octanol is 1:(2-4).

[0019] Further, solution A and the extractant are mixed in a volume ratio of 1:2 in S4.

[0020] Further, the S4 washing agent is 0.2 M hydrochloric acid solution.

[0021] Further, the S5 oxalic acid solution concentration is 0.5 M.

[0022] Further, the S6 vacuum extraction method is to first start a mechanical pump to extract the furnace to low vacuum, at which time the vacuum degree is about 10 -2 Pa, and then start a molecular pump to extract the furnace to high vacuum, at which time the vacuum degree is ≤10 -5 Pa.

[0023] Further, the S7 annealing condition introduces argon as a protective gas.

[0024] By using a mixed solution of dibutyl carbitol and secondary octanol as the extractant, and adjusting the ratio of the two, the mixed solution has excellent gold purification performance. Dibutyl carbitol, as a high-efficiency gold extractant, can quantitatively and selectively extract gold from hydrochloric acid solution, separating gold from other metal elements, and has high extraction efficiency. Secondary octanol can form unstable ion associates when extracting gold, which can be transferred to the organic phase, and has obvious gold extraction effect and large gold extraction capacity. Dibutyl carbitol and secondary octanol can play a synergistic effect under certain volume ratio, so that the extraction efficiency is high and the capacity is large. In addition, high-purity argon is introduced during the extraction and stripping process to remove oxygen and other impurity gases that may interfere with the reaction process, ensuring the purity of the reaction environment and the purity of the extraction product.

[0025] The two-stage melting process is used to obtain a gold target material with uniform composition and high mechanical strength. The vacuum melting furnace uses a medium-frequency induction heating method, which can quickly and uniformly heat the melt by adjusting the current frequency and power, avoiding the generation of impurities caused by local overheating. The stirrer is designed as a propeller type and is made of high-temperature resistant alloy. It is driven by a precise motor to perform three-dimensional stirring in the melt, ensuring the sufficient mixing and uniform distribution of the gold melt during the melting process. The first-stage melting process melts and mixes the gold raw material. Through the high-temperature environment of melting, low-melting-point impurities are evaporated or oxidized to remove, thereby improving the purity of gold. However, there may still be a problem of uneven distribution of gold at this time. The second melting is to heat and refine the gold after the preliminary melting. Through more sufficient stirring and mixing, the composition and organization distribution of gold are more uniform, and the internal segregation and performance difference phenomenon is reduced. Through appropriate holding time and slow cooling rate, a gold slab blank with small grains is obtained, and the compactness of the slab blank structure is effectively improved, so that the prepared target material has more excellent mechanical properties. In addition, the annealing process is carried out under argon protection to avoid oxidation or contamination of the slab blank during the annealing process, ensuring the quality and performance of the gold target material.

[0026] The beneficial effects of the present application are:

[0027] (1) The present application selects gold waste as the raw material of the target material, realizes the resource recovery and reuse of gold waste, reduces the waste of rare and precious metal resources, and meets the concept of sustainable development. By optimizing and controlling 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.

[0028] (2) By selecting and adjusting the mixed solution of dibutyl carbitol and secondary octanol as the extractant, the efficiency and selectivity of gold purification are significantly enhanced. Dibutyl carbitol can accurately extract gold from hydrochloric acid solution and effectively separate other metal elements; secondary 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 accuracy of the extraction process.

[0029] (3) The use of two-stage smelting process ensures the performance and quality of the gold target material. The preliminary smelting further removes impurities to ensure the purity of the target material; the secondary smelting makes the composition and organization distribution of gold more uniform, reduces internal segregation, and enhances the mechanical strength of the target material. In addition, insulation and slow cooling promote the formation of fine grains, improve the density of the plate blank, and improve the overall performance of the target material. Under the combined action of a series of measures, the prepared gold target material has uniform composition and high mechanical strength, meeting the demand of high-performance applications. DETAILED DESCRIPTION

[0030] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the specific embodiments, structures, features and effects according to the present application are described in detail as follows in combination with examples.

[0031] Example 1

[0032] S1: The recovered gold waste is sorted and treated to remove large particle 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 with uniform size;

[0033] S2: The gold waste is placed in a cleaning solution which is a mixed solution of sodium dodecyl sulfonate, sodium bicarbonate, ethanol and deionized water, and the mass ratio of sodium dodecyl sulfonate, sodium bicarbonate, ethanol and deionized water is 2:1:3:3. The cleaning solution needs to completely cover the gold waste, and at the same time, ultrasonic vibration is introduced, the vibration frequency is 5 kHz, the ultrasonic time is 30 min, then the gold waste is repeatedly cleaned with deionized water and dried in a vacuum drying oven, the drying temperature is 60 ℃, and the drying time is 12 h;

[0034] S3: The dried gold scrap is placed in a solution of concentrated hydrochloric acid and concentrated nitric acid mixed in a mass ratio of 1:3, ultrasonically dissolved at 80°C for 1 h, and stirred at a rotation speed of 500 r / min to obtain solution A;

[0035] S4: Solution A is mixed with an extractant in a volume ratio of 1:2, wherein the extractant is a solution of dibutyl carbitol and secondary octanol mixed in a volume ratio of 1:3, the pH of the mixed solution is adjusted to 4, high-purity argon is introduced into the mixed solution, the mixed solution is fully stirred at 60°C for 30 min, then is left to stand for 1 h, two-phase separation is performed using a separatory funnel, and the organic phase is further purified using a 0.2 M hydrochloric acid solution as a washing agent to obtain organic phase B;

[0036] S5: Organic phase B is heated to 85°C and high-purity argon is introduced, 0.5 M oxalic acid solution is added, and stirred for 2.5 h, then separated using a high-speed centrifuge at a rotation speed of 5000 r / min for 10 min, the precipitate is washed with deionized water, and is placed in a vacuum drying oven for drying, the drying temperature is 60°C, and the drying time is 12 h to obtain smelting raw material;

[0037] S6: The smelting raw material is placed in a graphite crucible, and the crucible is placed in a vacuum smelting furnace, a mechanical pump is first started to draw the furnace to a low vacuum, at this time the vacuum degree is about 10 -2 Pa, a molecular pump is then started to draw the furnace to a high vacuum, at this time the vacuum degree is ≤10 -5 Pa, an intermediate frequency induction heating method is adopted, the smelting time is 1 h, the smelting temperature is 1000°C, a propeller stirrer is started to stir the melt during smelting, the stirring speed is 800 r / min, and a gold ingot is obtained after rapid pouring;

[0038] S7: The obtained gold ingot is placed in a vacuum smelting furnace for secondary smelting, the secondary smelting time is 1.5 h, the secondary smelting temperature is 1150°C, the stirring speed is 1000 r / min, the annealing condition is 800°C for 6 h under argon as a protective gas, then slowly cooled to room temperature, and a gold sheet blank is obtained;

[0039] S8: The gold sheet blank is subjected to mechanical processing and surface polishing treatment to obtain the high-purity target material.

[0040] Example 2

[0041] S1: The recovered gold scrap is subjected to sorting treatment to remove large-particle impurities, then is placed in a ball mill for ball milling at a rotation speed of 350 r / min for 30 min to obtain gold scrap with uniform size;

[0042] S2: The gold scrap is placed in a cleaning solution which is a mixture of sodium dodecyl sulfonate, sodium bicarbonate, ethanol and deionized water, and the mass ratio of sodium dodecyl sulfonate, sodium bicarbonate, ethanol and deionized water is 2:1:3:3, the cleaning solution needs to completely cover the gold scrap, and at the same time, ultrasonic vibration is introduced, the vibration frequency is 5 kHz, the ultrasonic time is 30 min, then the gold scrap is repeatedly cleaned with deionized water and dried in a vacuum drying oven, the drying temperature is 60 ℃, and the drying time is 12 h;

[0043] S3: The dried gold scrap is placed in a solution mixed by concentrated hydrochloric acid and concentrated nitric acid according to a mass ratio of 1:3, ultrasonic dissolution is carried out at 80 ℃ for 1 h, and stirring is carried out at a rotating speed of 500 r / min, to obtain solution A;

[0044] S4: Solution A is mixed with an extractant according to a volume ratio of 1:2, the extractant is a solution mixed by dibutyl carbitol and secondary octanol according to a volume ratio of 1:2, the pH of the mixed solution is adjusted to 4.5, high-purity argon is introduced into the mixed solution, and the mixed solution is fully stirred at 60 ℃ for 30 min, then it is statically placed for 1 h, two-phase separation is carried out by using a separatory funnel, and the organic phase is further purified by using a 0.2 M hydrochloric acid solution as a washing agent, to obtain organic phase B;

[0045] S5: Organic phase B is heated to 85 ℃ and high-purity argon is introduced, a 0.5 M oxalic acid solution is added, stirring is carried out for 2.5 h, separation is carried out by using a high-speed centrifuge at a rotating speed of 5000 r / min for 10 min, the precipitate is washed with deionized water and dried in a vacuum drying oven, the drying temperature is 60 ℃, and the drying time is 12 h, to obtain smelting raw material;

[0046] S6: The smelting raw material is placed in a graphite crucible, and the crucible is placed in a vacuum smelting furnace, a mechanical pump is started to draw the furnace to low vacuum, at this time, the vacuum degree is about 10 -2 Pa, a molecular pump is started to draw the furnace to high vacuum, at this time, the vacuum degree is ≤10 -5 Pa, a medium-frequency induction heating method is adopted, the smelting time is 1 h, the smelting temperature is 1050 ℃, a propeller stirrer is started to stir the melt during smelting, the stirring speed is 800 r / min, and a gold ingot is obtained after rapid pouring;

[0047] S7: The obtained gold ingot is placed in a vacuum smelting furnace for secondary smelting, the secondary smelting time is 1.5 h, the secondary smelting temperature is 1170 ℃, the stirring speed is 1000 r / min, the annealing condition is that argon is used as a protective gas, the temperature is 800 ℃, the holding time is 5.5 h, and then slow cooling is carried out to room temperature, to obtain a gold plate blank;

[0048] S8: The gold plate blank is subjected to mechanical processing and surface polishing treatment to obtain the high-purity target material.

[0049] Example 3

[0050] S1: The recycled gold scrap is subjected to sorting treatment to remove large-particle impurities, and then is placed in a ball mill for ball milling at a speed of 350 r / min for 30 min to obtain gold scrap with uniform size;

[0051] S2: The gold scrap is placed in a cleaning solution which is a mixture of sodium dodecyl sulfonate, sodium bicarbonate, ethanol and deionized water, and the mass ratio of sodium dodecyl sulfonate, sodium bicarbonate, ethanol and deionized water is 2:1:3:3. The cleaning solution needs to completely cover the gold scrap, and at the same time, ultrasonic vibration is introduced, the vibration frequency is 5 kHz, the ultrasonic time is 30 min, and then the gold scrap is repeatedly cleaned with deionized water and dried in a vacuum drying oven, the drying temperature is 60 ℃, and the drying time is 12 h;

[0052] S3: The dried gold scrap is placed in a solution mixed from concentrated hydrochloric acid and concentrated nitric acid at a mass ratio of 1:3, ultrasonic dissolution is carried out at 80 ℃ for 1 h, and stirring is carried out at a speed of 500 r / min to obtain solution A;

[0053] S4: Solution A is mixed with an extractant at a volume ratio of 1:2, wherein the extractant is a solution of dibutyl carbitol and secondary octanol mixed at a volume ratio of 1:4, the pH of the mixed solution is adjusted to 5, high-purity argon is introduced into the mixed solution, and the mixed solution is fully stirred at 60 ℃ for 30 min, then it is left to stand for 1 h, two-phase separation is carried out by using a separatory funnel, and the organic phase is further purified by using 0.2 M hydrochloric acid solution as a washing agent to obtain organic phase B;

[0054] S5: Organic phase B is heated to 85 ℃ and high-purity argon is introduced, 0.5 M oxalic acid solution is added, stirring is carried out for 2.5 h, separation is carried out by using 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 temperature of 60 ℃ for 12 h to obtain smelting raw material;

[0055] S6: The smelting raw material is placed in a graphite crucible, and the crucible is placed in a vacuum smelting furnace. First, a mechanical pump is started to pump the furnace to low vacuum, at this time the vacuum degree is about 10 -2 Pa, then a molecular pump is started to pump the furnace to high vacuum, at this time the vacuum degree is ≤10 -5Pa, using a medium-frequency induction heating method, the smelting time is 1 h, the smelting temperature is 1100 DEG C, a propeller stirrer is started to stir the melt during smelting, the stirring speed is 800 r / min, and a golden ingot is obtained after rapid pouring;

[0056] S7: the obtained golden ingot is placed in a vacuum smelting furnace for secondary smelting, the time of the secondary smelting is 1.5 h, the temperature of the secondary smelting is 1200 DEG C, the stirring speed is 1000 r / min, the annealing condition is 800 DEG C for 5 h under argon as a protective gas, and then slow cooling to room temperature to obtain a gold sheet blank;

[0057] S8: the gold sheet blank is subjected to mechanical processing and surface polishing treatment to obtain the high-purity target material.

[0058] Comparative Example 1

[0059] In the present comparative example, the extractant is dibutyl carbitol, and the other steps are the same as those in Example 1.

[0060] Comparative Example 2

[0061] In the present comparative example, the extractant is secondary octanol, and the other steps are the same as those in Example 1.

[0062] Comparative Example 3

[0063] In the present comparative example, only one smelting process is performed, and the other steps are the same as those in Example 1.

[0064] The mass m1 of the gold scrap and the mass m2 of the prepared high-purity target material are measured respectively, and the recovery rate is calculated, that is, the recovery rate = m2 / m1 x 100%.

[0065] The Au content of the examples and the comparative examples is measured by an inductively coupled plasma mass spectrometer.

[0066] The density of the high-purity target material of the examples and the comparative examples is measured respectively. The actual density of the high-purity target material of the examples and the comparative examples is measured at 20 DEG C and one atmosphere by using the Archimedes drainage method, and the ratio of the actual density to the theoretical density is calculated, that is, the density = actual density / theoretical density x 100%.

[0067] The experimental results are arranged in the following table,

[0068]

[0069] It can be known from the experimental data that the mixed extractant prepared in the present application at a suitable ratio ensures the highest recycling rate of waste and the purity of the prepared gold target material meets the use requirements. Through optimization of the smelting process, a secondary refining step is added, and the gold target material with higher density and better quality is obtained.

[0070] The above merely describes the preferred embodiments of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed with the preferred embodiments as above, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, without departing from the technical solution of the present application. Any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, without departing from the technical solution of the present application, are still within the scope of the technical solution of the present application.

Claims

1. A process for preparing high-purity target materials based on gold scrap, characterized in that, The specific steps of the high-purity target material preparation process are as follows: S1: The recycled 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 with uniform size. S2: Place the gold waste in a cleaning solution that completely covers the gold waste, and simultaneously introduce ultrasonic vibration at a frequency of 5 kHz for 30 min. Then, repeatedly clean the gold waste with deionized water and place it in a vacuum drying oven to dry at a temperature of 60 ℃ for 12 h. S3: Place the dried gold waste in a strong acid mixture, sonicate it at 80 °C for 1 h, and stir it at 500 r / min to obtain solution A; S4: Mix solution A with the extractant, which is a mixture of dibutylcarbidol and 2-octanol, wherein the volume ratio of dibutylcarbidol to 2-octanol is 1:(2~4). Adjust the pH of the mixture to 4~5, and introduce high-purity argon gas into the mixture. Stir thoroughly 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 washing agent to obtain organic phase B. S5: Heat organic phase B to 85 °C and introduce high-purity argon gas, add oxalic acid solution, stir for 2.5 h, separate using a high-speed centrifuge at 5000 r / min for 10 min, wash the precipitate with deionized water, and dry it in a vacuum drying oven at 60 °C for 12 h to obtain the smelting raw material. S6: Place the smelting raw material in a graphite crucible and place the crucible in a vacuum melting furnace. Vacuum the furnace and use medium-frequency induction heating. The melting time is 1 hour and the melting temperature is 1000~1100 ℃. During the melting process, turn on the propeller stirrer to stir the melt at a stirring speed of 800 r / min. After rapid casting, gold ingots are obtained. S7: The obtained gold ingot is placed in a vacuum melting furnace for secondary melting. The secondary melting time is 1.5 h, the secondary melting temperature is 1150~1200 ℃, the stirring speed is 1000 r / min, and the annealing conditions are 800 ℃ for 5~6 h. Then it is slowly cooled to room temperature to obtain gold slab blank. S8: The gold plate blank is machined and surface polished to obtain the high-purity target material.

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

3.

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

2.

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

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

7. The process for preparing high-purity target material based on gold scrap according to claim 1, characterized in that, The vacuuming method in S6 is to first start the mechanical pump to evacuate the furnace to a low vacuum level of 10. -2 Pa, then start the molecular pump to evacuate the furnace to a high vacuum, at which point the vacuum level is ≤10. -5 Pa.

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

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