Mixing agent for K gold purification instead of aqua regia

Abstract

The invention relates to a mixing agent for purifying K gold by replacing aqua regia, and efficient purification of a K gold material is realized by replacing traditional aqua regia with an agricultural fertilizer calcium nitrate and toilet cleaning hydrochloric acid mixing agent. The technology comprises the steps of dissolving, filtering, reducing, cleaning and smelting, and finally a gold product with the purity not lower than 999% o is obtained. The reagents used in the method are all non-control chemicals, are wide in source, simple to operate and high in recovery rate, and are suitable for purification of the K gold material in the jewelry industry.

Description

Technical Field

[0001] The invention relates to the technical field of precious metal purification, and in particular to a process for purifying K gold by using a mixture of agricultural fertilizer calcium nitrate and toilet-cleaning hydrochloric acid instead of aqua regia. Background Art

[0002] Karat gold is a common precious metal alloy widely used in jewelry manufacturing. Karat gold materials usually contain copper, silver, nickel and other filling elements, which cannot be directly remelted and used. They need to be converted into pure gold with a purity of not less than 990‰ through a purification process. The traditional Karat gold purification process usually uses aqua regia (a mixture of nitric acid and hydrochloric acid) to dissolve the gold material, and then uses a reducing agent to reduce the gold ions to metallic gold. However, the nitric acid and hydrochloric acid in aqua regia are explosive and toxic chemicals, and their acquisition and use are strictly controlled. The operation is complicated and the cost is high. Therefore, it is of great practical significance to develop a Karat gold purification process that uses non-controlled chemicals, is simple to operate, environmentally friendly and efficient. Summary of the invention

[0003] The purpose of the present invention is to provide a mixture and process for purifying K gold instead of aqua regia, using agricultural fertilizer calcium nitrate and toilet cleaning hydrochloric acid mixture instead of aqua regia to achieve efficient purification of K gold material and obtain a gold product with a purity of not less than 990‰.

[0004] The technical solution of the present invention is as follows: (1) Dissolution step: Place K gold material in a container, add agricultural fertilizer calcium nitrate and toilet cleaning hydrochloric acid mixture, make the mixture liquid level 1.5-2 times higher than the K gold material, and heat until the K gold material is completely dissolved to form a gold-containing solution; (2) Filtration step: Add tap water to the gold-containing solution to precipitate silver chloride, and filter using quantitative filter paper to obtain a clear and transparent green gold-containing solution; (3) Reduction step: add excess anhydrous sodium sulfite powder to the filtered gold-containing solution and stir until the gold is completely precipitated to form sponge gold; (4) Cleaning step: Boil the sponge gold in tap water for 3 times to remove impurities; (5) Smelting step: The cleaned sponge gold is transferred to a gold melting bowl and smelted into gold particles using a welding torch to obtain a gold product with a purity of not less than 990‰.

[0005] The advantages of the present invention are: (1) Using a mixture of agricultural fertilizer calcium nitrate and toilet cleaning hydrochloric acid instead of aqua regia, which is widely available, cheap, and unregulated; (2) The process is simple to operate and is suitable for small-scale purification needs in the jewelry industry; (3) The recovery rate is high (not less than 98%), and the purity of gold products complies with the national standard (GB 11887-2012). BRIEF DESCRIPTION OF THE DRAWINGS

[0006] In the drawings of the specification Figure 1 This is a process flow chart of the present invention, showing the complete purification process from the dissolution of K gold material to the final gold product, specifically including the steps of gold dissolution, gold precipitation, smelting and detection.

Claims

1. Claim 1 (independent claim): A mixture for replacing aqua regia for purifying K gold, characterized in that: The following steps are involved: (1) Dissolution step: put the K gold material into a container, add agricultural fertilizer calcium nitrate and toilet cleaning hydrochloric acid mixture, make the mixture liquid level 1.5-2 times higher than the K gold material, and heat until the K gold material is completely dissolved to form a gold-containing solution; (2) Filtration step: Add tap water to the gold-containing solution to precipitate silver chloride, and filter using quantitative filter paper to obtain a clear and transparent green gold-containing solution; (3) Reduction step: add excess anhydrous sodium sulfite powder to the filtered gold-containing solution and stir until the gold is completely precipitated to form sponge gold; (4) Cleaning step: Boil the sponge gold in tap water for 3 times to remove impurities; (5) Smelting step: The cleaned sponge gold is transferred to a gold melting bowl and smelted into gold particles using a welding torch to obtain a gold product with a purity of not less than 990‰.

2. Claim 2 (dependent claim): The mixed agent for replacing aqua regia for purifying K gold according to claim 1, characterized in that: The agricultural fertilizer calcium nitrate is commercially available packaged calcium nitrate, the chemical formula of which is Ca(NO3)2·nH2O, and the purity is not less than 99%.

3. Claim 3 (dependent claim): The mixed agent for replacing aqua regia for purifying K gold according to claim 1, characterized in that: The toilet cleaning hydrochloric acid is commercially available toilet cleaning hydrochloric acid, and its hydrochloric acid mass fraction is 5%-10%.

4. Claim 4 (dependent claim): The mixed agent for replacing aqua regia for purifying K gold according to claim 1, characterized in that: The heating temperature is 80-100° C. and the heating time is 1-2 hours, until the K gold material is completely dissolved.

5. Claim 5 (dependent claim): The mixed agent for replacing aqua regia for purifying K gold according to claim 1, characterized in that: The amount of anhydrous sodium sulfite added is 1.5-2 times the theoretical calculated amount to ensure complete reduction of gold ions.

6. Claim 6 (dependent claim): The mixed agent for replacing aqua regia for purifying K gold according to claim 1, characterized in that: In the cleaning step of the sponge gold, ammonia water is used to soak and stir the sponge gold to further remove impurities and increase the gold purity to more than 999‰.

7. Claim 7 (dependent claim): The mixed agent for replacing aqua regia for purifying K gold according to claim 1, characterized in that: The K gold material includes 18K yellow gold, 18K white gold and 18K red gold, and its filling elements include one or more of copper, silver and nickel.

8. Claim 8 (dependent claim): The mixed agent for replacing aqua regia for purifying K gold according to claim 1, characterized in that: The reagents used in the process are all non-regulated chemicals with wide sources and simple operation, and are suitable for the purification of K gold materials in the jewelry industry.

9. Claim 9 (dependent claim): The mixed agent for replacing aqua regia for purifying K gold according to claim 1, characterized in that: The recovery rate of the process is not less than 98%, and the purity of the gold product meets the standard of "pure gold" in "GB 11887-2012 Provisions and Naming Methods for the Purity of Precious Metals for Jewelry".

10. Claim 10 (dependent claim): The mixed agent for replacing aqua regia for purifying K gold according to claim 1, characterized in that: The equipment used in the process includes a 500mL or 1000mL beaker, an electric furnace, an asbestos mesh, a funnel, a glass rod, a quantitative filter paper, a gold melting bowl and a combination welding tool.

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