Method for recovering high-purity rhodium from rhodium-containing tailings

Abstract

The invention belongs to the technical field of resource recycling and precious metal smelting, and relates to a method for recycling high-purity rhodium from rhodium-containing tailings. The method comprises the following steps: dissolving palladium refining hydrolysis residues by using aqua regia, sequentially carrying out rhodium precipitation pretreatment and rhodium precipitation operation to obtain rhodium precipitation rhodium salt, calcining the rhodium precipitation rhodium salt to obtain a calcined sample, and carrying out hydrogen reduction on the calcined sample; wherein the rhodium precipitation pretreatment process comprises the following steps: diluting a solution dissolved by aqua regia with water and hydrochloric acid, and then adding sodium chlorate for oxidation; the rhodium precipitation operation comprises the following steps: adding the rhodium precipitation reagent, and precipitating at 80-90 DEG C; the rhodium precipitation reagent is prepared from an organic matter, water and hydrochloric acid, wherein the organic matter is diethylenetriamine or triethanolamine. According to the method provided by the invention, high-purity rhodium can be collected from the palladium refining hydrolysis slag, the operation is simple and convenient, the impurity removal effect is good, and rhodium powder with qualified grade can be cast.

Description

Technical Field

[0001] The present invention relates to the technical field of resource recovery and precious metal smelting, and relates to a method for recovering high-purity rhodium from rhodium-containing tailings. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Copper anode mud (insoluble solid produced at the anode during electrolytic refining of crude copper) contains valuable metals such as gold, silver, platinum, palladium, rhodium, and iridium, which need to be recovered. Palladium refining hydrolysis slag is a process material produced after recovering valuable metals such as gold, silver, platinum, and palladium during the process of platinum-palladium refining and purification of copper anode mud. This process material contains valuable metals such as rhodium, and rhodium in palladium refining hydrolysis slag needs to be recovered.

[0004] At present, the method for recovering rhodium is generally chlorination method or sodium bisulfate melting method, which converts rhodium into soluble salt and transfers it into solution, and then uses solvent extraction method, ion exchange method, precipitation method or multiple methods to cooperate with each other for refining and purification. However, the inventors have found that the existence of rhodium in palladium refining hydrolysis slag is different from the raw materials of the existing rhodium recovery method, and it contains a large amount of other metal elements. Therefore, it is difficult to recover rhodium from palladium refining hydrolysis slag using the existing rhodium recovery method to efficiently extract rhodium from palladium refining hydrolysis slag. Summary of the invention

[0005] In order to overcome the deficiencies in the prior art, the purpose of the present invention is to provide a method for recovering high-purity rhodium from rhodium-containing tailings. The method provided by the present invention can recover high-purity rhodium from palladium refining hydrolysis slag, has the advantages of simple operation and good impurity removal effect, and can cast rhodium powder with qualified grade.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] In a first aspect, a rhodium precipitation reagent for extracting rhodium from palladium refining hydrolysis slag is prepared from organic matter, water and hydrochloric acid in a volume ratio of 15-25:15-25:50-70, the organic matter is diethylenetriamine or triethanolamine, and the mass concentration of the hydrochloric acid is 36-38%.

[0008] Palladium refining hydrolysis slag contains a large amount of impurity elements (such as Cu, Au, Pb, Pd, Pt, etc.). When palladium refining hydrolysis slag is dissolved and rhodium is precipitated, these impurity elements are easily precipitated with Rh, thereby affecting the purity of Rh. Studies have shown that diethylenetriamine or triethanolamine can precipitate Rh with high selectivity. However, when only diethylenetriamine or triethanolamine is used, its precipitation efficiency for Rh is low. Therefore, the present invention uses water and hydrochloric acid and diethylenetriamine or triethanolamine for preparation. After experiments, it is unexpectedly found that the rhodium precipitation reagent prepared by the above ratio can precipitate rhodium in the solution after the palladium refining hydrolysis slag is dissolved with high yield and high selectivity.

[0009] On the other hand, a method for recovering high-purity rhodium from rhodium-containing tailings comprises dissolving palladium refining hydrolysis slag with aqua regia, then sequentially performing rhodium precipitation pretreatment and rhodium precipitation operation to obtain rhodium precipitation rhodium salt, then calcining the rhodium precipitation rhodium salt to obtain a calcined sample, and subjecting the calcined sample to hydrogen reduction;

[0010] The process of rhodium precipitation pretreatment is as follows: diluting the solution dissolved in aqua regia with water and hydrochloric acid, and then adding sodium chlorate for oxidation;

[0011] The process of rhodium precipitation operation is: add the above-mentioned rhodium precipitation reagent and precipitate at 80-90°C.

[0012] Firstly, the present invention adopts aqua regia to dissolve palladium refining hydrolysis slag, thereby obtaining a rhodium-containing solution; secondly, the rhodium precipitation pretreatment of the present invention comprises hydrochloric acid absorption and sodium chlorate oxidation, which can not only reduce sodium chlorate, but also facilitate the separation of palladium and rhodium, while inhibiting the precipitation of other metal impurities; then, by adding the rhodium precipitation reagent provided by the present invention, rhodium in the rhodium-containing solution can be precipitated with high yield and high selectivity, thereby greatly reducing the entry of impurity elements into the rhodium precipitated rhodium salt; thirdly, the present invention selects the method of calcination and hydrogen reduction to reduce rhodium, thereby avoiding the problem of reduced rhodium purity caused by the reduction of other impurities in formic acid reduction, thereby recovering elemental rhodium from the palladium refining hydrolysis slag with high purity and high yield.

[0013] The beneficial effects of the present invention are:

[0014] The invention uses aqua regia to dissolve rhodium-containing substances in palladium refining hydrolysis slag, adopts a solution prepared by diethylenetriamine or triethanolamine, water and hydrochloric acid as a rhodium precipitation reagent, and can precipitate rhodium into rhodium salt with high yield and high selectivity, thereby solving the problem of infiltration of other harmful impurities; finally, high-purity metal rhodium powder is obtained through calcination and hydrogen reduction, and the recovery rate is high and the grade is high (the purity can reach 99.99%). BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0016] Figure 1 The present invention is a flow chart of a method for recovering high-purity rhodium from rhodium-containing tailings according to an embodiment of the present invention. DETAILED DESCRIPTION

[0017] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0018] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0019] In view of the fact that it is difficult to efficiently extract rhodium from palladium refining hydrolysis slag using existing methods, the present invention provides a method for recovering high-purity rhodium from rhodium-containing tailings.

[0020] A typical embodiment of the present invention provides a rhodium precipitation reagent for extracting rhodium from palladium refining hydrolysis slag, which is made of organic matter, water and hydrochloric acid in a volume ratio of 15-25:15-25:50-70, the organic matter is diethylenetriamine or triethanolamine, and the mass concentration of the hydrochloric acid is 36-38%.

[0021] In some embodiments, the volume ratio of organic matter, water and hydrochloric acid is 18-22:18-22:56-64.

[0022] In some embodiments, the preparation method is: firstly add hydrochloric acid to water, and then dropwise add the organic matter. When dropping the organic matter, stir to ensure that the temperature does not exceed 50°C.

[0023] Another embodiment of the present invention provides a method for recovering high-purity rhodium from rhodium-containing tailings, wherein the palladium refining hydrolysis slag is dissolved by aqua regia, and then a rhodium precipitation pretreatment and a rhodium precipitation operation are sequentially performed to obtain a rhodium precipitation rhodium salt, and then the rhodium precipitation rhodium salt is calcined to obtain a calcined sample, and the calcined sample is subjected to hydrogen reduction;

[0024] The process of rhodium precipitation pretreatment is as follows: diluting the solution dissolved in aqua regia with water and hydrochloric acid, and then adding sodium chlorate for oxidation;

[0025] The process of rhodium precipitation operation is: add the above-mentioned rhodium precipitation reagent and precipitate at 80-90°C.

[0026] In some embodiments, the temperature for dissolving palladium refining hydrolysis slag with aqua regia is 70-80°C.

[0027] In some embodiments, the temperature of the pre-treatment for rhodium precipitation is 75-85°C.

[0028] In some embodiments, in the rhodium precipitation operation, the ratio of the rhodium precipitation reagent to the rhodium-containing material is 1L: 100-200g.

[0029] In some embodiments, the calcination temperature is 750-850° C. and the calcination time is 7-9 hours.

[0030] In some embodiments, the temperature of hydrogen reduction is 600-800°C.

[0031] In some embodiments, after the palladium refining hydrolysis slag is acidified and impurities are removed by hydrochloric acid, the palladium refining hydrolysis slag after impurities removal is dissolved by aqua regia. Hydrochloric acid is used to remove some of the impurity metals that are easily soluble in acid, thereby reducing the types of impurities introduced during the rhodium precipitation process. Unless otherwise specified, the mass concentration of the hydrochloric acid described in the present invention is 36-38%. Specifically, the temperature for acidifying and impurities removal of palladium refining hydrolysis slag with hydrochloric acid is 70-80°C. The impurity removal efficiency under this condition is higher.

[0032] In some embodiments, the precipitated rhodium salt is subjected to at least one purification treatment and then calcined, and the extraction process is as follows: the precipitated rhodium salt is dissolved in aqua regia, and then the precipitated rhodium salt is subjected to a pre-treatment and a precipitated rhodium operation in sequence. Through multiple purification treatments, the content of impurity metals in the precipitated rhodium salt can be further reduced.

[0033] In some embodiments, the calcined sample is subjected to zinc pulverization, and then subjected to hydrochloric acid dezincification, followed by rhodium precipitation pretreatment, rhodium precipitation operation, and calcination. Zinc pulverization can further remove metal impurities in the calcined sample.

[0034] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in combination with specific embodiments and comparative examples.

[0035] The hydrochloric acid used in the following examples is analytically pure hydrochloric acid (mass concentration is 37%).

[0036] Example

[0037] A method for recovering high-purity rhodium from rhodium-containing tailings, such as Figure 1 As shown, the steps are as follows:

[0038] 1) Hydrochloric acid removal (removal of lead, iron, zinc and other impurity metals)

[0039] The palladium refining hydrolysis slag (metal composition is shown in Table 1) is placed in a titanium barrel, and a hydrochloric acid solution is prepared in the titanium barrel in a ratio of 1:1 between water and hydrochloric acid. The amount of the hydrochloric acid solution is 5 to 6 times the weight of the hydrolysis slag. The temperature is raised to 70 to 80°C under stirring, and the reaction is performed for 2 hours. The residue is cooled to 30 to 40°C and filtered. The residue is fully soaked and washed for more than 3 times, and the residue is collected.

[0040] Table 1 Metal composition of palladium refining hydrolysis slag

[0041]

[0042] 2) Dissolution in aqua regia

[0043] Put the filter residue into a titanium barrel, add appropriate amount of water to slurry, prepare aqua regia according to the solid-liquid ratio of 1:8, add aqua regia into the titanium barrel in small amounts and multiple times, start stirring, turn on the heating system to heat the solution to 70-80℃, react for 3-4 hours, boil after the filter residue is completely dissolved, and concentrate after concentrating to a certain amount. Add hydrochloric acid solution to drive out nitrate until no yellow smoke is generated, turn off the stirrer, turn off the heating system, and use pure water to clean the tools. After cooling slightly, perform vacuum filtration and collect the filtrate.

[0044] 3) Configuration of rhodium precipitation reagent

[0045] Take one portion of deionized water, add one portion of deionized water to the clean container, then slowly add three portions of hydrochloric acid while stirring with a glass rod, take one portion of reagent (diethylenetriamine), slowly drip the reagent into the container with a dropper, stir while adding, and ensure that the temperature does not exceed 50°C. After the reagent is added, wash the glass rod and dropper with deionized water, cool, then put it in a bottle, label it and set it aside. (The volume ratio of deionized water: reagent: hydrochloric acid is 1:1:3)

[0046] 4) Rhodium precipitation operation

[0047] The rhodium-containing filtrate is sampled and tested. According to the test results, water and hydrochloric acid are added to dilute (the ratio of water to hydrochloric acid is 2:1) to 15g / L, which is used to reduce the grade of other impurity metals in the solution and facilitate the subsequent rhodium precipitation operation. The solution is heated to 80°C, sodium chlorate is weighed according to the ratio of rhodium content (rhodium content refers to the mass of rhodium element in the solution) 1 / 5-1 / 4, and slowly added to the solution. Oxidation is beneficial to the separation of palladium and rhodium, and the precipitation of other metal impurities is inhibited. After no chlorine is released, rhodium precipitation is carried out. An appropriate amount of rhodium precipitation reagent is added according to the ratio of rhodium precipitation reagent to rhodium content 1L:150g, and the addition speed is controlled to 15L / h. The temperature is maintained at 80-90°C. After addition, react for 0.5h and take samples. After cooling to below 40°C, filter operation is carried out.

[0048] According to the impurity content in the sample (the sample sent for inspection is the filtered solution), if the impurity content in the solution is high, the aqua regia dissolution and rhodium precipitation operation are repeated again until the impurity content meets the requirements. The comparative analysis of the pre-solution and post-solution of rhodium precipitation is shown in Table 2-1 and Table 2-2.

[0049] Table 2-1 Comparison of metal elements in the pre-liquid and post-liquid of rhodium precipitation

[0050]

[0051] Table 2-2 Comparison of metal elements in the pre-liquid and post-liquid of rhodium precipitation

[0052]

[0053]

[0054] 5) Muffle furnace calcination

[0055] Place the filtered rhodium salt in a clean and dry crucible, cover it to prevent dust from entering, slowly put it into a muffle furnace, and heat it in stages until it reaches 800°C. Keep the temperature constant for 8 hours, at which time black rhodium oxide is generated. Close the muffle furnace and cool it naturally to room temperature.

[0056] 6) Zinc pulverization

[0057] If the impurities in the samples taken after calcination do not meet the requirements, the rhodium oxide can no longer be dissolved in aqua regia. Zinc powder can be crushed and placed in a mixed PP tank. Five times the weight of zinc powder can be weighed and mixed evenly. A layer of zinc powder is spread on the bottom of the nickel-chromium alloy tank. The mixed materials are placed in the nickel-chromium alloy tank, and a layer of zinc powder is covered on the surface of the materials to prevent the loss of rhodium caused by oxidation and volatilization of zinc powder. The nickel-chromium alloy tank is placed in a muffle furnace, heated to 800°C, kept at a constant temperature for 8 hours, and taken out after cooling. The calcined rhodium-containing material is transferred to a titanium barrel, covered with an appropriate amount of clean water, and stirred to form a slurry. The hydrochloric acid solution is slowly added and stirred continuously to prevent the tank from overflowing. After there is no obvious reaction after adding hydrochloric acid, the acid addition is stopped, and the filtering operation is repeated. The filter residue is dissolved in aqua regia-precipitated rhodium-calcined to achieve the purpose of purifying rhodium oxide.

[0058] 7) Hydrogen reduction of rhodium powder

[0059] Take out the rhodium oxide in the crucible, crush it with a stainless steel spoon, transfer the rhodium oxide powder to a quartz boat, spread it evenly, put it into the hydrogen reduction furnace, connect the hydrogen reduction furnace, hydrogen generator, nitrogen tank, pressure reducing valve and flowmeter, turn on the nitrogen, use soapy water to detect the air tightness of each connection part, and reinforce it in time if there is leakage; after passing nitrogen for 10 minutes, evacuate the oxygen in the hydrogen reduction furnace, set the heating curve to 30℃, heat to 700℃ in 60 minutes, keep it at 700℃ for 6 hours, and start the heating program. When the temperature of the hydrogen reduction furnace reaches 500℃, open the hydrogen pressure reducing valve, open the hydrogen inlet valve, slowly pass hydrogen, and control the flow rate to 3-5L / h. And gradually close the nitrogen inlet valve. After the reduction at 700℃ is completed, the program stops and the temperature is lowered. When the temperature of the hydrogen reduction furnace drops to 500℃, open the nitrogen inlet valve, slowly pass nitrogen, and control the flow rate to 3-5L / h. Gradually close the hydrogen pressure reducing valve and the hydrogen inlet valve. When the hydrogen reduction furnace cools down to room temperature, close the nitrogen pressure reducing valve and the nitrogen inlet valve. Open the hydrogen reduction furnace and take out the quartz boat. Take out the rhodium powder from the quartz boat, grind the rhodium powder evenly with a grinding dish, take samples for testing, and the purity is 99.90% to 99.99%, and the recovery rate is 96% to 98%.

[0060] Optimization of rhodium precipitation reagent:

[0061] D-sodium isoascorbate and diethylenetriamine were used as rhodium precipitation reagents respectively, and the rhodium precipitation effect was compared with the rhodium precipitation reagent used in this embodiment. The experimental method was the same as the rhodium precipitation operation in step 4) of this embodiment. The results are shown in Table 3.

[0062] Table 3 Comparison of optimization data of rhodium precipitation reagents

[0063] Name of medicine used Rhodium precipitation pre-liquid content Rhodium precipitation liquid content Sodium D-isoascorbate 4.36 3.56 Diethylenetriamine 4.36 1.94 The rhodium precipitation reagent of this embodiment 4.36 0.4

[0064] Table 3 shows that in the rhodium precipitation system of the present invention, diethylenetriamine has a better effect as a rhodium precipitation reagent, but the effect of using diethylenetriamine as a rhodium precipitation reagent after it is made into a proportioning liquid is more obvious.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A rhodium precipitation reagent for extracting rhodium from palladium refining hydrolysis slag, characterized in that: The invention is prepared from organic matter, water and hydrochloric acid in a volume ratio of 15-25:15-25:50-70, wherein the organic matter is diethylenetriamine or triethanolamine, and the mass concentration of the hydrochloric acid is 36-38%.

2. The rhodium precipitation reagent as claimed in claim 1, characterized in that, The volume ratio of organic matter, water and hydrochloric acid is 18-22:18-22:56-64.

3. The rhodium precipitation reagent as claimed in claim 1, characterized in that, The preparation method is as follows: firstly, hydrochloric acid is added into water, and then organic matter is added dropwise.

4. A method for recovering high-purity rhodium from rhodium-containing tailings, characterized in that: Aqua regia is used to dissolve palladium refining hydrolysis slag, and then rhodium precipitation pretreatment and rhodium precipitation operation are carried out in sequence to obtain rhodium precipitation rhodium salt, and then the rhodium precipitation rhodium salt is calcined to obtain a calcined sample, and the calcined sample is subjected to hydrogen reduction; The process of rhodium precipitation pretreatment is as follows: diluting the solution dissolved in aqua regia with water and hydrochloric acid, and then adding sodium chlorate for oxidation; The process of rhodium precipitation operation is: adding the rhodium precipitation reagent described in any one of claims 1 to 3, and precipitating at 80 to 90° C.

5. The method according to claim 4, characterized in that: The temperature for dissolving palladium refining hydrolysis slag with aqua regia is 70-80°C.

6. The method according to claim 4, characterized in that: The temperature of the pretreatment for rhodium precipitation is 75-85°C; Alternatively, in the rhodium precipitation operation, the ratio of the rhodium precipitation reagent to the rhodium-containing material is 1L: 100-200g.

7. The method according to claim 4, characterized in that: The calcination temperature is 750-850°C and the calcination time is 7-9h; Alternatively, the temperature of hydrogen reduction is 600-800°C.

8. The method according to claim 4, characterized in that: After the palladium refining hydrolysis slag is acidified and impurities are removed by hydrochloric acid, the palladium refining hydrolysis slag after impurities are dissolved by aqua regia; preferably, the temperature for acidifying and impurities removal of the palladium refining hydrolysis slag by hydrochloric acid is 70-80°C.

9. The method according to claim 4, characterized in that: The rhodium salt is purified at least once and then calcined. The extraction process is as follows: the rhodium salt is added into aqua regia to dissolve, and then the rhodium pretreatment and rhodium precipitation operation are sequentially performed.

10. The method according to claim 4, characterized in that: The calcined sample is subjected to zinc pulverization, and then zinc is removed by hydrochloric acid, followed by rhodium precipitation pretreatment, rhodium precipitation operation, and calcination.

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