Environment-friendly platinum group noble metal slag analysis method

Abstract

The invention relates to an environment-friendly platinum group noble metal slag analysis method which comprises the following steps: S1, sampling: sampling a sample to a cremation cup, and synchronously performing compensation analysis; s2, stirring: uniformly stirred reagents are added into the sample, the reagents comprise anhydrous sodium carbonate, borax, silicon dioxide, soluble starch, calcium fluoride, copper alloy and a covering agent, and a mixture is obtained; s3, melting is conducted, specifically, the mixture is completely melted and then poured into a casting mold to be cooled, and a copper buckle is formed; s4, acid dissolution: cleaning out the copper buckle in the cremation cup, dissolving the copper buckle in concentrated nitric acid, and filtering out residual metal slag; and S5, weighing: drying and weighing the metal slag, and calculating the content of the metal slag in the sample. The method belongs to a fire assaying treatment method and has the advantage of simple operation, but lead oxide is replaced by copper alloy, the toxicity of reagents is effectively reduced, and the treatment is more environment-friendly.

Description

Technical Field

[0001] The invention relates to the technical field of precious metal recovery, and in particular to an environmentally friendly platinum group precious metal slag analysis method. Background Art

[0002] Platinum group refers to the third main group elements in the periodic table, including precious metals such as ruthenium, rhodium, iridium and osmium. The semiconductor and optoelectronic industries use evaporation processes in their manufacturing processes. The walls of the evaporation process chambers are protected by anti-fog plates, which are used to block unused evaporation materials to prevent them from adhering to the walls of the chambers and being difficult to remove, causing damage to equipment components. The filter residues from cleaning the anti-fog plates contain precious metals such as ruthenium, rhodium, iridium and osmium, which have high recycling value.

[0003] Chinese patent CN 106501044A discloses a method for quantitative determination of precious metal elements and a pretreatment method for fire assay. The ingredients include sodium carbonate, lead oxide, silicon dioxide, shed sand, silver nitrate and auxiliary materials, and the auxiliary materials are nitric acid or starch. This method mainly determines metals such as gold, platinum and palladium. Although this method is simple to use and can be quickly ash blown, the lead used is highly toxic and causes serious pollution to the human body and the environment. This problem has always troubled precious metal analysis workers.

[0004] Chinese patent CN 111044344A discloses a method for determining the content of platinum group metals in a catalyst, wherein the cosolvent includes cuprous oxide, sodium tetraborate, sodium carbonate, sea sand, and potassium hydrogen tartrate. Cuprous oxide has both reducing properties and the ability to generate copper. However, osmium will generate volatile oxides after oxidation (the boiling point of osmium oxide is 130°C), which will be lost at high temperatures exceeding 1000°C during the melting process. For the above reasons, if other platinum group elements in a sample are to be analyzed, fire assay is generally not used for analysis, but other chemical analysis methods are used.

[0005] Therefore, it is necessary to develop a more environmentally friendly platinum group precious metal slag analysis method to solve the above problems. Summary of the invention

[0006] The main purpose of the present invention is to provide an environmentally friendly platinum group precious metal slag analysis method, which can meet the needs of rapid determination of platinum group metals and reduce the toxicity of reagents to make the treatment more environmentally friendly.

[0007] The present invention achieves the above-mentioned purpose through the following technical scheme: an environmentally friendly platinum group precious metal slag analysis method, the steps comprising:

[0008] S1. Sampling: Samples are taken into the cremation cup and compensation analysis is performed simultaneously;

[0009] S2. Stirring: adding a well-mixed reagent to the sample, wherein the reagent includes anhydrous sodium carbonate, borax, silicon dioxide, soluble starch, calcium fluoride, copper alloy and a covering agent to obtain a mixture;

[0010] S3, melting: the mixture is completely melted, and then poured into a casting mold and cooled to form a copper buckle;

[0011] S4, acid dissolution: clean out the copper buckle in the cremation cup, dissolve the copper buckle in concentrated nitric acid, and filter out the remaining metal slag;

[0012] S5. Weighing: dry and weigh the metal slag to calculate the content of the metal slag in the sample.

[0013] Specifically, the reagent includes 30 parts by mass of anhydrous sodium carbonate, 20 parts by mass of borax, 10 parts by mass of silicon dioxide, 5 parts by mass of soluble starch, 10 parts by mass of calcium fluoride, 10 parts by mass of copper alloy and 14 parts by mass of covering agent.

[0014] Specifically, the copper alloy is a silver-copper alloy, the melting temperature in step S3 is 1100° C., and the melting time is 1 hour.

[0015] The beneficial effects of the technical solution of the present invention are:

[0016] This method belongs to the fire assay treatment method and has the advantage of simple operation. However, copper alloy is used instead of lead oxide to transfer heat and help other substances react and separate. Therefore, no elemental lead will be generated in the molten reaction product, which effectively reduces the toxicity of the reagent and makes the treatment more environmentally friendly. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below with reference to specific embodiments.

[0018] Example:

[0019] The environmentally friendly platinum group precious metal slag analysis method of the present invention comprises the following steps:

[0020] S1. Sampling: Samples are taken into the cremation cup and compensation analysis is performed simultaneously.

[0021] S2. Stirring: Add a well-mixed reagent to the sample, wherein the reagent includes 30 parts by mass of anhydrous sodium carbonate, 20 parts by mass of borax, 10 parts by mass of silicon dioxide, 5 parts by mass of soluble starch, 10 parts by mass of calcium fluoride, 10 parts by mass of copper alloy and 14 parts by mass of a covering agent to obtain a mixture.

[0022] This method belongs to the fire assay method, which has the advantage of simple operation, but copper alloy is used instead of lead oxide to transfer heat and help other substances react and separate, so no single lead will be generated in the molten reaction product, which effectively reduces the toxicity of the reagent and makes the treatment more environmentally friendly. Anhydrous sodium carbonate, as an alkaline solvent, can form salts with acidic substances. Borax and silicon dioxide, as acidic solvents, can react with metal oxides in the sample to form borates and silicates. Soluble starch and calcium fluoride, as reducing agents, can reduce metal oxides that do not react with borax and silicon dioxide to metal elements (including metal oxides of the platinum group). The covering agent can block the molten fluid from the air during melting to prevent the reduced metal elements from being oxidized again.

[0023] S3. Melting: The mixture is completely melted and then poured into a mold to cool to form a copper buckle.

[0024] The copper alloy is a silver-copper alloy. Because the boiling point of the alloy is lower than the boiling point of each single metal it contains. The boiling point of silver is 2210℃, and the boiling point of copper is 2567℃, but the boiling point of the silver-copper alloy can be as low as 779℃ to 1090℃, so this can greatly reduce the temperature required for melting. The melting temperature here is 1100℃ and the melting time is 1 hour. During the melting stage, the oxides of the platinum group precious metals will be reduced to simple substances and then captured by copper, while other impurities will react with other components in the reagent to form salt substances and separate in the molten copper.

[0025] S4. Acid dissolution: Clean out the copper buckle in the cremation cup, dissolve it in concentrated nitric acid, and filter out the remaining metal slag.

[0026] Concentrated nitric acid has strong oxidizing properties and can dissolve inactive metals such as copper and silver, but it cannot dissolve platinum group metals. The reason why copper-silver alloy is used as the solvent is to reduce the melting temperature and facilitate acid dissolution. The metallic copper and silver in the copper buckle will be oxidized by concentrated nitric acid to form copper nitrate, which then enters the solution. Other salt substances in the copper buckle will also be dissolved by nitric acid, so that only platinum group precious metals will be precipitated in the form of metal slag because they cannot be dissolved. The copper and silver dissolved in nitric acid can also be recycled without increasing the cost of raw materials.

[0027] S5. Weighing: Dry and weigh the metal slag to calculate the content of metal slag in the sample.

[0028] Because other impurities have basically been dissolved by concentrated nitric acid, the effective components of the metal slag are platinum group precious metals, so a more accurate content can be obtained by weighing after drying.

[0029] Table 1 shows the ruthenium content of ruthenium-containing ash measured using the method of the present invention.

[0030] Table 1:

[0031] Sample No. (Ruthenium) Actual ratio (%) Results of this patent (%) RSD(%) Difference rate Ruthenium-containing ash-1 36.955％ 36.944 0.03 excellent Ruthenium-containing ash-2 25.011％ 24.993 0.07 excellent

[0032] It can be seen that the measured RSD (Relative Standard Deviation) is only one ten-thousandth of an order of magnitude. This indicates that the accuracy is very high. The physical and chemical properties of platinum group metals are similar, so the situation of other precious metals will not be repeated.

[0033] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. An environmentally friendly platinum group precious metal slag analysis method, characterized by the steps of include: S1. Sampling: Samples are taken into the cremation cup and compensation analysis is performed simultaneously; S2. Stirring: adding a well-mixed reagent to the sample, wherein the reagent includes anhydrous sodium carbonate, borax, silicon dioxide, soluble starch, calcium fluoride, copper alloy and a covering agent to obtain a mixture; S3, melting: the mixture is completely melted, and then poured into a casting mold and cooled to form a copper buckle; S4, acid dissolution: clean out the copper buckle in the cremation cup, dissolve the copper buckle in concentrated nitric acid, and filter out the remaining metal slag; S5. Weighing: dry and weigh the metal slag to calculate the content of the metal slag in the sample.

2. The environmentally friendly platinum group precious metal slag analysis method according to claim 1, characterized in that: The reagents include 30 parts by mass of anhydrous sodium carbonate, 20 parts by mass of borax, 10 parts by mass of silicon dioxide, 5 parts by mass of soluble starch, 10 parts by mass of calcium fluoride, 10 parts by mass of copper alloy and 14 parts by mass of covering agent.

3. The environmentally friendly platinum group precious metal slag analysis method according to claim 2, characterized in that: The copper alloy is a silver-copper alloy, and the melting temperature in step S3 is 1100° C. and the melting time is 1 hour.