Method for preparing liquid from indissolvable platinum group metal material

Abstract

The invention provides a method for preparing liquid from an indissolvable platinum group metal material. The method comprises the following steps: (1) alkaline leaching and desilicication: reacting the indissolvable platinum group metal material with a sodium hydroxide solution; (2) neutralizing and activating: reacting the filter residue obtained in the step (1) with sulfuric acid; and (3) multiple oxidation system dissolution and liquid preparation: mixing the filter residues obtained in the step (2) with a liquid preparation agent, and introducing chlorine gas for reaction. According to the method, effective leaching of the platinum group metal in the indissolvable platinum group metal material is achieved, the dissolution rate of the platinum group metal reaches 90% or above, and the liquid making agent formed by mixing sodium chlorate, hydrogen peroxide and nitric acid and chlorine form a multiple oxidation system; the indissolvable platinum group metal material reacts with the platinum group metal in the material from the inside and outside of the indissolvable platinum group metal material, so that the dissolution speed and the dissolution rate of the indissolvable platinum group metal material are greatly improved through the synergistic effect, and serious dispersion and loss of the platinum group metal are avoided.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgy of platinum group metals, and in particular to a method for preparing liquid from refractory platinum group metal materials. Background Art

[0002] In the process of purification and refining of platinum group metals, due to the complexity of raw material composition and the diversity of chemical reactions, some difficult-to-handle intermediate materials are often produced. These materials include but are not limited to distillation return materials, chlorination insoluble materials and acid leaching materials. The platinum group metals in these intermediate materials often exist in extremely stable forms with extremely low activity. Traditional liquid making methods such as acid-base dissolution, oxidation-reduction, etc. are difficult to effectively dissolve them, thus hindering the further recovery and purification of platinum group metals. For such insoluble intermediate materials with extremely low activity, although traditional pyrometallurgical treatment methods can recover the platinum group metals therein to a certain extent, there are many disadvantages. Pyrometallurgical treatment usually needs to be carried out at high temperatures, which not only consumes a lot of energy, but also leads to serious dispersion of platinum group metals. Platinum group metals may be attached to waste materials such as slag and smoke in the form of tiny particles, making it difficult to achieve efficient recovery. In addition, pyrometallurgical treatment may also lead to the loss of precious metals such as platinum and palladium, especially when treating materials containing high levels of impurities, the loss of platinum and palladium is particularly serious. Summary of the invention

[0003] In view of the problems of low recovery rate and serious loss of platinum group metals in insoluble platinum group metal materials in the above-mentioned prior art, the present invention provides a method for making liquid from insoluble platinum group metal materials, which can effectively recover the platinum group metals in the insoluble materials, and the recovery rate of platinum group metals reaches more than 90%.

[0004] To achieve the above object, the technical solution of the present invention is as follows:

[0005] A method for preparing a liquid of a refractory platinum group metal material comprises the following steps:

[0006] (1) Alkaline leaching desiliconization: Mix the insoluble platinum group precious metal material with sodium hydroxide solution at a solid-liquid ratio of 1:6-8, react at 80-85°C for 1-1.5h, and filter;

[0007] (2) Neutralization and activation: the filter residue obtained in step (1) is mixed with sulfuric acid at a solid-liquid ratio of 1:4-5, reacted at 75-80° C. for 2-2.5 h, and filtered;

[0008] (3) Dissolution and liquid preparation by multiple oxidation system: The filter residue obtained in step (2) is mixed with a liquid-forming agent at a solid-liquid ratio of 1:5-6, chlorine gas is introduced at 70-75° C. to react for 3-4 hours, and filtered. The filtrate obtained is a platinum group metal solution. The liquid-forming agent is a mixed solution of sodium chlorate, hydrogen peroxide and nitric acid.

[0009] Furthermore, the concentration of the sodium hydroxide in step (1) is 30-40%.

[0010] Furthermore, it is characterized in that the concentration of sulfuric acid in step (2) is 3-4 mol / L.

[0011] Furthermore, the preparation method of the liquid-forming agent in step (3) comprises the following steps: mixing sodium chlorate and hydrogen peroxide in a volume ratio of 3-4:1, stirring for 30-35 minutes, adding 5-8% nitric acid of the total volume of the mixed solution to the mixed solution, and stirring for 10-15 minutes.

[0012] Furthermore, in step (3), the concentration of the sodium chlorate used to prepare the liquid-forming agent is 35-40%, the concentration of the hydrogen peroxide is 5-8%, and the concentration of the nitric acid is 10-15%.

[0013] The reaction mechanism of the present invention is as follows:

[0014] In the alkaline leaching and desiliconization step, sodium hydroxide solution is used to remove impurities such as silicon dioxide from the material, which not only improves the solubility of the material, but also provides favorable conditions for the subsequent dissolution of platinum group metals;

[0015] In the neutralization and activation step, the acidic conditions of sulfuric acid are used to further activate the platinum group metals in the material, making it easier to react with the subsequent oxidant, thereby increasing the dissolution rate of the platinum group metals;

[0016] The multiple oxidation system dissolution and liquid-making step uses a mixed solution of sodium chlorate, hydrogen peroxide and nitric acid as a liquid-making agent, creating a strong oxidizing environment for the insoluble platinum group metal materials. Chlorine, as a gaseous oxidant, can penetrate the tiny pores of the insoluble platinum group metal materials, fully contact and react with the platinum group metals inside the insoluble platinum group metal materials. Sodium chlorate, hydrogen peroxide and nitric acid provide continuous oxidizing ability in the aqueous solution, synergistically promoting the dissolution of platinum group metals.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The invention provides a method for preparing liquid of a hardly soluble platinum group metal material. The method realizes effective leaching of platinum group metals in the hardly soluble platinum group metal material through a process flow of alkali leaching desiliconization, neutralization activation and multiple oxidation system dissolution and preparation of liquid, and the dissolution rate of platinum group metals reaches more than 90%. A liquid preparation agent formed by mixing sodium chlorate, hydrogen peroxide and nitric acid forms a multiple oxidation system with chlorine gas, which reacts with the platinum group metals in the hardly soluble platinum group metal material from the inside and outside of the material, respectively. The synergistic effect greatly improves the dissolution speed and dissolution rate of the hardly soluble platinum group metal material, and avoids serious dispersion and loss of the platinum group metals. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The embodiments of the present invention are further described below with reference to the accompanying drawings, in which:

[0020] Figure 1 The process flow chart of liquid preparation of insoluble platinum group metal materials is shown. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0022] Example 1

[0023] A method for preparing a liquid of a refractory platinum group metal material comprises the following steps:

[0024] (1) Alkaline leaching desiliconization: The insoluble platinum group precious metal material is mixed with a 40% sodium hydroxide solution at a solid-liquid ratio of 1:6, reacted at 85°C for 1.5 hours, and filtered;

[0025] (2) Neutralization and activation: the filter residue obtained in step (1) was mixed with 4 mol / L sulfuric acid at a solid-liquid ratio of 1:4, reacted at 80° C. for 2.5 h, and filtered;

[0026] (3) Dissolution and liquid preparation by multiple oxidation system: the filter residue obtained in step (2) is mixed with a liquid-forming agent at a solid-liquid ratio of 1:5, chlorine gas is introduced at 75° C. for reaction for 3 hours, and the filtrate is filtered. The obtained filtrate is a platinum group metal solution; wherein the preparation method of the contrast agent comprises the following steps: sodium chlorate with a concentration of 40% and hydrogen peroxide with a concentration of 5% are mixed at a volume ratio of 3:1, stirred for 30 minutes, nitric acid with a concentration of 5% of the total volume of the mixed solution is added to the mixed solution, and the concentration of the nitric acid is 10%, and stirred for 10 minutes.

[0027] The dissolution effect of this example is shown in Table 1.

[0028] Table 1 Dissolution effect of Example 1

[0029] Pt Pd R Ir Refractory platinum group precious metal materials (g) 171 139 32 11 Platinum group metal solution (g) 168 135 29 10 Dissolution rate (%) 98.01 97.12 90.62 90.91

[0030] Example 2

[0031] A method for preparing a liquid of a refractory platinum group metal material comprises the following steps:

[0032] (1) Alkaline leaching desiliconization: The insoluble platinum group precious metal material is mixed with a 30% sodium hydroxide solution at a solid-liquid ratio of 1:8, reacted at 80°C for 1 hour, and filtered;

[0033] (2) Neutralization and activation: the filter residue obtained in step (1) was mixed with 3 mol / L sulfuric acid at a solid-liquid ratio of 1:5, reacted at 75° C. for 2 h, and filtered;

[0034] (3) Dissolution and liquid preparation by multiple oxidation system: the filter residue obtained in step (2) is mixed with a liquid-forming agent at a solid-liquid ratio of 1:6, chlorine gas is introduced at 70°C for reaction for 4 hours, and the filtrate is filtered to obtain a platinum group metal solution; wherein the preparation method of the contrast agent comprises the following steps: sodium chlorate with a concentration of 35% and hydrogen peroxide with a concentration of 8% are mixed at a volume ratio of 4:1, stirred for 35 minutes, nitric acid with a concentration of 8% of the total volume of the mixed solution is added to the mixed solution, and the concentration of the nitric acid is 15%, and stirred for 15 minutes.

[0035] The dissolution effect of this example is shown in Table 2.

[0036] Table 2 Dissolution effect of Example 2

[0037] Pt Pd R Ir Refractory platinum group precious metal materials (g) 342 278 64 22 Platinum group metal solution (g) 335 272 63 22 Dissolution rate (%) 97.95 97.84 98.44 100

[0038] The invention provides a method for preparing liquid of a hardly soluble platinum group metal material. The method realizes effective leaching of platinum group metals in the hardly soluble platinum group metal material through a process flow of alkali leaching desiliconization, neutralization activation and multiple oxidation system dissolution and preparation of liquid, and the dissolution rate of platinum group metals reaches more than 90%. A liquid preparation agent formed by mixing sodium chlorate, hydrogen peroxide and nitric acid forms a multiple oxidation system with chlorine gas, which reacts with the platinum group metals in the hardly soluble platinum group metal material from the inside and outside of the material, respectively. The synergistic effect greatly improves the dissolution speed and dissolution rate of the hardly soluble platinum group metal material, and avoids serious dispersion and loss of the platinum group metals.

[0039] Some exemplary embodiments of the present invention are described above. It can be understood that the above embodiments are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention. The features in these embodiments can be recombined in a suitable manner, and the scheme obtained thereby is still within the protection scope required by the present invention. Based on the above embodiments, all other embodiments obtained by those skilled in the art without making creative work, that is, all modifications, equivalent substitutions and improvements made within the spirit and principles of this application, fall within the protection scope required by the present invention.

Claims

1. A method for preparing a liquid of a poorly soluble platinum group metal material, characterized in that: The steps include: (1) Alkaline leaching desiliconization: Mix the insoluble platinum group precious metal material with sodium hydroxide solution at a solid-liquid ratio of 1:6-8, react at 80-85°C for 1-1.5h, and filter; (2) Neutralization and activation: the filter residue obtained in step (1) is mixed with sulfuric acid at a solid-liquid ratio of 1:4-5, reacted at 75-80° C. for 2-2.5 h, and filtered; (3) Dissolution and liquid preparation by multiple oxidation system: The filter residue obtained in step (2) is mixed with a liquid-forming agent at a solid-liquid ratio of 1:5-6, chlorine gas is introduced at 70-75° C. to react for 3-4 hours, and filtered. The filtrate obtained is a platinum group metal solution. The liquid-forming agent is a mixed solution of sodium chlorate, hydrogen peroxide and nitric acid.

2. The method for preparing a liquid of a hardly soluble platinum group metal material according to claim 1, characterized in that: The concentration of the sodium hydroxide in step (1) is 30-40%.

3. The method for preparing a liquid of a hardly soluble platinum group metal material according to claim 1, characterized in that: The concentration of sulfuric acid in step (2) is 3-4 mol / L.

4. The method for preparing a liquid of a hardly soluble platinum group metal material according to claim 1, characterized in that: The preparation method of the liquid-forming agent in step (3) comprises the following steps: mixing sodium chlorate and hydrogen peroxide in a volume ratio of 3-4:1, stirring for 30-35 minutes, adding 5-8% nitric acid of the total volume of the mixed solution to the mixed solution, and stirring for 10-15 minutes.

5. The method for preparing a liquid of a hardly soluble platinum group metal material according to claim 1 or 4, characterized in that: In step (3), the concentration of the sodium chlorate used to prepare the liquid-forming agent is 35-40%, the concentration of the hydrogen peroxide is 5-8%, and the concentration of the nitric acid is 10-15%.

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