High-purity gold wet refining and purifying method

Abstract

The invention discloses a high-purity gold wet refining and purifying method, and belongs to the technical field of precious metal metallurgy. According to the method, the gold raw material is subjected to bead spraying, granulation and aqua regia dissolution, the sponge gold is obtained through filtration and reduction, the high-purity gold meeting GB / T25933-2010 can be obtained after the sponge gold is washed and calcined, and the high-purity gold can be used for electronic industries such as integrated circuits and semiconductor devices. According to the method, the high-purity gold can be obtained through direct one-step purification of the gold ingot with the grade of 99.95% or above through the wet processes such as dissolution, filtration, reduction and washing, the whole process has the beneficial effects of being easy to operate, high in raw material adaptability, high in direct recovery rate and low in economic cost, energy saving and environmental protection are facilitated, and the high industrial popularization value is embodied.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of precious metal metallurgy, in particular to a high-purity gold wet refining purification method. BACKGROUND

[0002] High-purity gold is one of the important basic materials in the electronic industry such as integrated circuits and semiconductor devices due to its excellent physical and chemical properties such as low resistance, good thermal and electrical conductivity, and easy bonding, and its purity (mass fraction) is generally required to be above 99.999%. At present, the main methods for producing high-purity gold in China are chemical reduction method, solvent extraction method, and electrolytic refining method. The solvent extraction method mainly uses the ability of gold ions to form stable complexes with various organic chemical reagents for purification, and its process is simple, but the organic solvent has the problems of flammability and explosion safety and environmental protection. Although the electrolytic refining method has simple equipment and stable operation, it has poor adaptability to raw materials, and generally requires the raw material grade to be at least 99.99% or above, and a large amount of precious metals are occupied for electrolysis, resulting in large capital occupation and low utilization rate. The chemical reduction method generally uses aqua regia to dissolve and uses oxalic acid or sodium sulfite to reduce the solution after nitrate removal to obtain high-purity gold, but the nitrate removal process generates harmful nitrogen oxides, and the operating environment is poor. In addition, the oxalic acid reduction reaction is relatively slow and requires a long time, and the sodium sulfite reduction introduces sodium salt, which has a certain impact on the quality of high-purity gold.

[0003] The patent "A high-purity gold extraction method" CN201510130070.3 discloses a method for purifying high-purity gold by wet method, which comprises the following steps: dissolving, reducing, secondary dissolving, secondary reducing, which is essentially different from the method of the present application. The patent "A production process of high-purity gold" CN201910633224.9 discloses a high-purity gold refining method, which is characterized by aqua regia gold melting, urea nitrate removal, sodium sulfite reduction, acid leaching, and smelting to obtain high-purity gold. The use of urea as a nitrate removal agent and the use of sodium sulfite as a reducing agent are essentially different from the method of the present application. SUMMARY

[0004] The present application aims to provide a method for wet refining and purifying high-purity gold with high production efficiency, short process flow, and less accumulation of precious metals.

[0005] The technical solution adopted by the present application is as follows: A, sprinkle beads: gold raw materials are sprinkled to obtain granular gold particles with a particle size of 0.7-1mm; B, dissolving: the granular gold particles obtained in step A are dissolved with aqua regia to obtain a crude gold solution; C, dilution, cooling and filtering: the crude gold solution obtained in step B is diluted and cooled, and then filtered after cooling to obtain a gold solution; D, reduction: adding a reducing agent to the gold solution obtained in step C to perform reduction, and after sufficient reaction, performing solid-liquid separation to obtain a reduction mother liquor and sponge gold; E, washing and calcination: performing dilute hydrochloric acid and dilute nitric acid boiling washing on the sponge gold obtained in step D, and after the boiling washing is completed, performing calcination on the sponge gold to obtain high-purity gold.

[0006] The gold raw material in step A includes gold ingots with a grade of 99.95% or above or other sponge gold raw materials.

[0007] The aqua regia ratio in step B is different according to the state of the gold raw material. If the gold raw material is a gold particle, the amount of nitric acid added is 0.6 times the weight of the gold. If the gold raw material is sponge, the amount of nitric acid added is 0.45 times the weight of the gold. The amount of hydrochloric acid added is 2.5 times the weight of the gold regardless of the state of the raw material. The dissolution temperature is 70-80℃, and the dissolution time is 3-5h.

[0008] The dilution standard in step C is that the gold concentration is 100-200g / L, the cooling temperature is below 15℃, and the filtration is performed by first using 1 layer of 0.22μm PP filter membrane to perform suction filtration to obtain a primary filtrate, and then using 3-4 layers of double-circle qualitative filter paper to perform natural filtration on the primary filtrate to obtain a secondary filtrate, i.e., a gold-containing solution.

[0009] The reducing agent in step D is a mixture of hydrazine hydrate and hydrochloric acid, and the preparation ratio is hydrazine hydrate: water: hydrochloric acid = 1:1:2. The amount of addition is 0.9-1.1 times the weight of the gold. The reduction temperature is below 40℃, and the reduction time is controlled to be 30-60min. The reduction control yield is about 95%.

[0010] The sponge gold boiling washing standard in step E is that the dilute hydrochloric acid boiling washing is performed once at a temperature of 80℃ for a constant temperature time of ≥30min, and the dilute nitric acid boiling washing is performed three times at a temperature of 80℃ for a constant temperature time of ≥30min. The sponge gold calcination temperature is 650℃, and the constant temperature time is ≥90min.

[0011] The technical scheme provided by the present application has the following beneficial effects: (1) The present application controls the amount of nitric acid added during the dissolution process, and after the dissolution is completed, there is no need to use organic reagents such as urea and ethanol to remove the nitrate. On the one hand, this shortens the process flow and saves the recovery cycle. On the other hand, it avoids the introduction of C in the organic reagent, effectively controlling the quality of high-purity gold.

[0012] (2) The present application removes most of the silver in the raw material through dilution and cooling, 1-2 layers of 0.22μm PP filter membrane suction filtration, and 3-4 layers of filter paper natural filtration. At the same time, the use of an acidic reducing agent prepared from hydrazine hydrate and hydrochloric acid selectively reduces gold, leaving the base metal impurities in the reduction mother liquor, and removing the small amount of silver and base metal brought in during the reduction process through hydrochloric acid boiling washing and nitric acid boiling washing, effectively controlling the quality of high-purity gold.

[0013] (3) The whole process of the application is simple in process flow, strong in raw material adaptability, short in process flow, high in production efficiency, small in noble metal occupation, low in economic cost, and the produced high-purity gold meets the requirements of relevant standards and can meet the use of the electronic industry such as integrated circuits and semiconductor devices, and has high industrial popularization value. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 A flow chart of a high-purity gold wet refining and purification method provided by the application. DETAILED DESCRIPTION

[0015] In order to further understand the content of the application, the application will be described in detail in combination with the drawings and examples.

[0016] The concept and technical effects of the application will be described clearly and completely in combination with examples, so as to fully understand the purpose, features and effects of the application. Obviously, the described examples are only part of the examples of the application, but not all examples. Based on the examples of the application, other examples obtained by those skilled in the art without creative labor are within the protection scope of the application. Example 1

[0017] The high-purity gold wet refining and purification method provided by the application has the specific process as shown in Figure 1 The steps are as follows: A, sprinkle beads: 10000g of 99.99% bank gold ingot is obtained by sprinkling beads to obtain granular gold particles with a particle size of 0.7-1mm; B, dissolving: 10000g of the granular gold particles obtained in step A is dissolved with aqua regia, 6000mL of nitric acid and 25000mL of hydrochloric acid are added, the temperature is raised to 80℃, and the solution is dissolved for 5h to obtain a crude gold solution; 643.52g of gold particles cannot be dissolved, that is, the actual gold weight in the crude gold solution is 9356.48g; C, dilution, cooling and filtration: high-purity water is added to the crude gold solution obtained in step B to dilute the gold concentration to 100g / L, snow ice is added to cool the solution to below 7℃, and after cooling, 1 layer of 0.22μm PP filter membrane is used for suction filtration to obtain a first filtrate, and the first filtrate is naturally filtered using 3 layers of double-circle qualitative filter paper to obtain 93000mL of gold-containing solution; D, reduction: 9200mL of prepared reducing agent is slowly added to the gold-containing solution obtained in step C, the amount of reducing agent added is 0.983 times the amount of reduced gold, and the reducing agent is prepared according to the following ratio: hydrazine hydrate: water: hydrochloric acid = 1:1:2, the reduction temperature is 30℃, the reduction time is 30min, and after the reaction is completed, solid-liquid separation is performed to obtain 102200mL of reduction mother liquor and 8420.83g of sponge gold; E, washing and calcination: add 10000 mL of dilute hydrochloric acid with a ratio of hydrochloric acid: water = 1:1 to the sponge gold obtained in step D, and heat to 80°C for 30 min. After the sponge gold is washed to neutral, add 10000 mL of dilute nitric acid with a ratio of nitric acid: water = 1:1, heat to 80°C for 30 min, and then wash to neutral. Repeat the nitric acid washing process for 3 times, and replace the nitric acid each time. After the washing is completed, the sponge gold is calcined at 650°C for 90 min to obtain 8030.88 g of high-purity gold, with a direct reduction yield of 85.83%. The impurities of the sample meet the requirements of the high-purity gold standard, as shown in Table 1. Example 2

[0018] A, sprinkling beads: the gold raw material of 19676.93 g in this example 2 is in a sponge shape, so it does not need to be sprinkled with beads; B, dissolution: dissolve the sponge gold of 19676.93 g in step A with aqua regia, add 8854 mL of nitric acid and 49192 mL of hydrochloric acid, heat to 70°C for 4 h, and obtain a crude gold solution; 10.08 g of gold particles cannot be dissolved, i.e., the actual gold weight in the crude gold solution is 19666.85 g; C, dilution, cooling and filtration: add high-purity water to the crude gold solution obtained in step B to dilute to a gold concentration of 100 g / L, add snow ice to cool the solution to 7°C, and then use 1 layer of 0.22 μm PP filter membrane to perform suction filtration to obtain a first filtrate. The first filtrate is naturally filtered using 3 layers of double-circle qualitative filter paper to obtain a gold-containing solution of 197000 mL; D, reduction: slowly add 21000 mL of prepared reducing agent to the gold-containing solution obtained in step C, the amount of reducing agent is 1.068 times the amount of reduced gold, and the reducing agent is prepared according to the following ratio: hydrazine hydrate: water: hydrochloric acid = 1:1:2, the reduction temperature is 30°C, the reduction time is 60 min, and after the reaction is completed, solid-liquid separation is performed to obtain a reduction mother liquor of 218000 mL and sponge gold of 18683.51 g; E, washing and calcination: add 20000 mL of dilute hydrochloric acid with a ratio of hydrochloric acid: water = 1:1 to the sponge gold obtained in step D, and heat to 80°C for 30 min. After the sponge gold is washed to neutral, add 20000 mL of dilute nitric acid with a ratio of nitric acid: water = 1:1, heat to 80°C for 30 min, and then wash to neutral. Repeat the nitric acid washing process for 3 times, and replace the nitric acid each time. After the washing is completed, the sponge gold is calcined at 650°C for 90 min to obtain 18549.20 g of high-purity gold, with a direct reduction yield of 94.32%. The impurities of the sample meet the requirements of the high-purity gold standard, as shown in Table 1. Example 3

[0019] A, sprinkling beads: 30000 g of 99.95% bank gold ingots are sprinkled with beads to obtain granular gold particles with a particle size of 0.7-1 mm; B, Dissolution: The granular gold particles 30000 g from step A were dissolved with aqua regia, 18000 mL of nitric acid and 75000 mL of hydrochloric acid were added, and the solution was heated to 80°C and kept constant for 5 hours to obtain a crude gold solution; 42.08 g of gold particles failed to dissolve, i.e. the actual gold content in the crude gold solution was 29957.92 g; C, Dilution, cooling and filtration: high-purity water was added to the crude gold solution obtained in step B to dilute it to a gold concentration of 150 g / L, and snow ice was added to cool the solution to 10°C. After cooling, 1 layer of 0.22 μm PP filter membrane was used for suction filtration to obtain a primary filtrate, and 4 layers of double-circle qualitative filter paper were used for natural filtration of the primary filtrate to obtain a gold-containing solution of 200000 mL; D, Reduction: The gold-containing solution obtained in step C was slowly added with the prepared reducing agent 30500 mL, the amount of reducing agent was 1.018 times the amount of reduced gold, and the reducing agent was prepared according to the following ratio: hydrazine hydrate: water: hydrochloric acid = 1:1:2, the reduction temperature was 40°C, the reduction time was 60 min, and after the reaction was completed, solid-liquid separation was performed to obtain a reduction mother liquor of 230500 mL and sponge gold of 28160.45 g; E, Washing and calcination: 30000 mL of dilute hydrochloric acid with a ratio of hydrochloric acid to water of 1:1 was added to the sponge gold obtained in step D, and the temperature was raised to 80°C and kept constant for 30 min. After the sponge gold was washed to neutral, 30000 mL of dilute nitric acid with a ratio of nitric acid to water of 1:1 was added, and the temperature was raised to 80°C and kept constant for 30 min before being washed to neutral. This nitric acid washing process was repeated 3 times, and new nitric acid was used each time. After the washed sponge gold was calcined at 650°C for 90 min, high-purity gold of 27803.99 g was obtained, with a direct reduction yield of 92.81%, and the impurities met the requirements of high-purity gold standards, as shown in Table 1. Example 4

[0020] A, Spraying beads: 29500 g of 99.95% bank gold ingots were sprayed to obtain granular gold particles with a particle size of 0.7-1 mm; B, Dissolution: 29500 g of granular gold particles from step A were dissolved with aqua regia, 17700 mL of nitric acid and 73750 mL of hydrochloric acid were added, and the solution was heated to 80°C and kept constant for 5 hours to obtain a crude gold solution; 402.73 g of gold particles failed to dissolve, i.e. the actual gold content in the crude gold solution was 29097.27 g; C, Dilution, cooling and filtration: high-purity water was added to the crude gold solution obtained in step B to dilute it to a gold concentration of 150 g / L, and snow ice was added to cool the solution to 15°C. After cooling, 1 layer of 0.22 μm PP filter membrane was used for suction filtration to obtain a primary filtrate, and 4 layers of double-circle qualitative filter paper were used for natural filtration of the primary filtrate to obtain a gold-containing solution of 190000 mL; D, Reduction: The prepared reducing agent 31500 mL was slowly added to the gold-containing solution obtained in step C, the amount of reducing agent was 1.083 times the amount of reduced gold, the reducing agent was prepared according to the following ratio: hydrazine hydrate: water: hydrochloric acid = 1:1:2, the reduction temperature was 40℃, the reduction time was 60 min, after the reaction was completed, solid-liquid separation was carried out, and 221500 mL of reduction mother liquor and 28224.35 g of sponge gold were obtained; E, Washing and calcination: 30000 mL of dilute hydrochloric acid with a ratio of hydrochloric acid: water = 1:1 was added to the sponge gold obtained in step D, and the temperature was raised to 80℃ and kept for 30 min. After the sponge gold was washed to neutral, 30000 mL of dilute nitric acid with a ratio of nitric acid: water = 1:1 was added, and the temperature was raised to 80℃ and kept for 30 min, then washed to neutral. The sponge gold after washing with nitric acid was calcined at 650℃ for 90 min to obtain high-purity gold 27933.38 g, with a direct reduction yield of 96.00%, and the impurities of the sample met the requirements of high-purity gold standard, as shown in Table 1. Example 5

[0021] A, Spraying beads: The gold raw material 12700 g in this example 5 was in the form of sponge, so it did not need to be sprayed with beads; B, Dissolution: The granular gold particles 12700 g in step A were dissolved with aqua regia, nitric acid 5715 mL, hydrochloric acid 31500 mL, the temperature was raised to 70℃ and kept for 3 h to obtain a crude gold solution; 63.50 g of gold particles could not be dissolved, i.e. the actual gold content in the crude gold solution was 12636.50 g; C, Dilution, cooling and filtration: high-purity water was added to the crude gold solution obtained in step B to dilute the gold concentration to 200 g / L, and snow ice was added to cool the solution to 15℃. After cooling, 1 layer of 0.22 μm PP filter membrane was used for suction filtration to obtain a first filtrate, and 4 layers of double-circle qualitative filter paper were used for natural filtration to obtain a gold-containing solution 63000 mL; D, Reduction: The prepared reducing agent 12649 mL was slowly added to the gold-containing solution obtained in step C, the amount of reducing agent was 1.001 times the amount of reduced gold, the reducing agent was prepared according to the following ratio: hydrazine hydrate: water: hydrochloric acid = 1:1:2, the reduction temperature was 30℃, the reduction time was 45 min, after the reaction was completed, solid-liquid separation was carried out, and 75650 mL of reduction mother liquor and 11751.95 g of sponge gold were obtained; E, washing and calcination: add 10000 mL of dilute hydrochloric acid with hydrochloric acid: water = 1:1 to the sponge gold obtained in step D, heat to 80°C and keep constant for 30 min. After washing the sponge gold to neutral, add 10000 mL of dilute nitric acid with nitric acid: water = 1:1, heat to 80°C and keep constant for 30 min, then wash to neutral. This nitric acid washing process is repeated for 3 times, and new nitric acid is used each time. After the sponge gold obtained by washing is calcined at 650°C for 90 min, high-purity gold 11519.43 g is obtained, with a reduction direct recovery rate of 91.16%, and the impurities of the sample meet the requirements of the high-purity gold standard, as shown in Table 1 below.

Claims

1. The present application provides a high-purity gold wet refining purification method, comprising the following steps: A, sprinkle beads: gold raw materials through sprinkle beads to get the particle size of 0.7-1mm granular gold particles; B, dissolution: the granular gold particles obtained in step A are dissolved with aqua regia to obtain a crude gold solution; C, dilution cooling and filtration: the crude gold solution obtained in step B is diluted and cooled, and after cooling, filtration is carried out to obtain a gold solution; D, reduction: adding a reducing agent to the gold solution obtained in step C to reduce, and after sufficient reaction, solid-liquid separation is carried out to obtain a reduction mother liquor and sponge gold; E, washing and calcination: the sponge gold obtained in step D is boiled and washed with dilute hydrochloric acid and dilute nitric acid, and after calcination, high-purity gold is obtained.

2. The method for purifying high purity gold by wet process according to claim 1, characterized in that: The gold raw material in step A includes gold ingots with a grade of 99.95% and above or other sponge gold raw materials.

3. The method of claim 1, wherein the method is characterized by: The aqua regia in step B is prepared by adding nitric acid in an amount of 0.45-0.6 times the weight of gold and hydrochloric acid in an amount of 2.5 times the weight of gold; the dissolution temperature is 70-80℃, and the dissolution time is 3-5h.

4. The method of claim 1, wherein the method is characterized by: In step C, the dilution standard is gold concentration of 100-150g / L, the cooling temperature is below 15℃, and the filtration is first performed using 1-2 layers of 0.22μm PP filter membrane to obtain a primary filtrate, and then using 3-4 layers of double-circle qualitative filter paper to perform natural filtration to obtain a secondary filtrate, i.e., a gold-containing solution.

5. The method of claim 1, wherein the method is characterized by: The reducing agent in step D is a mixture of hydrazine hydrate and hydrochloric acid, with a preparation ratio of hydrazine hydrate: water: hydrochloric acid = 1:1:2.5, and the addition amount is 0.9-1.1 times the weight of gold, and the reduction temperature is below 40℃.

6. The method of claim 1, wherein the method is characterized by: In step E, the sponge gold boiling and washing standard is 1 pass of dilute hydrochloric acid boiling and washing at a temperature of 80℃ and a constant temperature time of ≥30min; 3 passes of dilute nitric acid boiling and washing at a temperature of 80℃ and a constant temperature time of ≥30min; and the sponge gold calcination temperature is 650℃, and the constant temperature time is ≥90min.

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