阅读说明：本技术 一种从含铑废水中回收铑的方法 (Method for recovering rhodium from rhodium-containing wastewater ) 是由 董岩 李坚 武陈 安欣 刘玉芬 袁滨 于 2019-08-30 设计创作，主要内容包括：本发明涉及一种从含铑废水中回收铑的方法,其包括：将含铑废水经冷等离子体辉光放电处理,使得所述含铑废水中的铑离子还原成铑单质。本发明采用冷等离子体辉光放电方法对含铑废水中的铑离子进行还原分离,避免了大量还原试剂的引入,简化了回收过程,降低了回收成本。同时,本发明方法还具有高选择性和高分离性的优点,铑回收率可高达97％以上,且回收的铑纯度在99.95％以上。(The invention relates to a method for recovering rhodium from rhodium-containing wastewater, which comprises the following steps: and (3) carrying out cold plasma glow discharge treatment on the rhodium-containing wastewater to reduce rhodium ions in the rhodium-containing wastewater into a rhodium simple substance. The invention adopts the cold plasma glow discharge method to carry out reduction separation on rhodium ions in the rhodium-containing wastewater, avoids the introduction of a large amount of reduction reagents, simplifies the recovery process and reduces the recovery cost. Meanwhile, the method also has the advantages of high selectivity and high separability, the recovery rate of rhodium can reach more than 97%, and the purity of the recovered rhodium is more than 99.95%.)

1. A method for recovering rhodium from rhodium-containing wastewater comprises the step of subjecting the rhodium-containing wastewater to cold plasma glow discharge treatment so as to reduce rhodium ions in the rhodium-containing wastewater into rhodium simple substances.

2. The method according to claim 1, wherein the method for treating the rhodium-containing wastewater by cold plasma glow discharge comprises the following steps:

placing a mixed solution formed by mixing rhodium-containing wastewater and an additive in a plasma discharge gas atmosphere;

under the action of alternating current, rhodium ions in the mixed solution are reduced to form a rhodium simple substance by plasma formed by discharging the plasma discharge gas.

3. The method according to claim 2, wherein the ratio of the molar amount of rhodium ions in the rhodium-containing wastewater to the molar amount of the additive is 1 (1-15), preferably 1 (3.5-15).

4. A process according to claim 2 or 3, characterised in that the additive comprises 4-8mol/L concentrated hydrochloric acid and/or pure perchloric acid.

5. The method of any of claims 2-4, wherein the plasma discharge gas comprises one or more of an inert gas, nitrogen, and air.

6. A method according to any of claims 2-5, characterized in that the voltage of the alternating current is 150-400V, preferably 200-300V; the reduction time is 5-15min, preferably 5-13 min.

7. The method according to any one of claims 1-6, further comprising:

filtering and washing the product obtained after the discharge treatment to obtain a rhodium metal crude product;

and sequentially roasting and reducing the crude rhodium metal product to obtain rhodium powder.

8. The method of claim 7, wherein the method of washing treatment comprises: and washing with absolute ethyl alcohol and deionized water in sequence.

9. A method according to claim 7 or 8, characterized in that the temperature of the roasting treatment is 400-800 ℃, preferably 550-700 ℃; and/or the time of the roasting treatment is 5.5 to 24.5 hours, preferably 8 to 22 hours.

10. The method according to any one of claims 7 to 9, wherein the temperature of the reduction treatment is 500 to 1000 ℃, preferably 700 to 900 ℃; and/or the time of the reduction treatment is 4 to 12 hours, preferably 5 to 10 hours.

Technical Field

The invention belongs to the technical field of precious metal recovery, and particularly relates to a method for recovering rhodium from rhodium-containing wastewater.

Background

The rhodium-containing catalyst has wide application in catalytic hydrogenation, methanol carbonylation to prepare acetic acid and hydroformylation of olefin, and is an indispensable important raw material even in the fields of automobile exhaust purification, electroplating and the like. Particularly in the field of oxo synthesis, domestic enterprises need more than 10 tons of rhodium catalysts every year, most of the rhodium catalysts need to be imported from abroad, the price of the rhodium catalysts is always high, and the rhodium has great economic and social values in recovery due to the high price of the rhodium.

The rhodium-containing wastewater is mainly generated from wastewater discharged by abnormal operation in the current carbonyl synthesis field, electroplating industry, rhodium smelting and the like. These wastewaters tend to have a relatively low rhodium content, are relatively corrosive and are not environmentally friendly. Two methods, i.e., a chemical method and a physical method, are generally adopted in the treatment of wastewater containing noble metals in various countries, and include, for example, a precipitation separation method, an ion exchange method, an electrodeposition method, an adsorption method, and the like. Among these methods, the precipitation separation method and the ion exchange method are most widely used.

The precipitation separation method is that a certain amount of chemical reagent is added into the waste water to react with noble metal ions to generate precipitation, and a product which is insoluble in water is separated and recovered. The precipitation separation method has the characteristics of mature technology, simple process, easy operation and the like, but has smaller application range and more strict conditions for rhodium metal ions and is not easy to use.

The ion exchange method achieves the purpose of separation and recovery based on ion exchange, has the advantages of wide application in metal recovery, simple operation, large treatment capacity and the like, but has the disadvantages of high resin price, large amount of reagents required by regeneration, easy generation of new waste liquid, environmental pollution, narrow working application range of the resin and high requirement on working conditions for the recovery of precious metals.

The traditional method for recovering rhodium from rhodium-containing wastewater at present has the defects of long process flow, low recovery rate, high impurity content, high environmental pollution, high cost and the like. Therefore, the problem is that research and development of a method for efficiently, greenly and economically recovering rhodium from rhodium-containing wastewater are urgently needed.

Disclosure of Invention

The invention aims to solve the technical problem of providing a method for recovering rhodium from rhodium-containing wastewater aiming at the defects of the prior art. The method adopts the cold plasma glow discharge treatment on the rhodium-containing wastewater, so that rhodium ions in the rhodium-containing wastewater are reduced into a rhodium simple substance, the introduction of a large amount of reducing agents is avoided, the recovery process is simplified, and the recovery cost is reduced. Meanwhile, the method also has the advantages of high selectivity and high separability, and the recovery rate and the purity of the recovered rhodium are high.

Therefore, the invention provides a method for recovering rhodium from rhodium-containing wastewater, which comprises the step of subjecting the rhodium-containing wastewater to cold plasma glow discharge treatment so as to reduce rhodium ions in the rhodium-containing wastewater into rhodium simple substances.

In some embodiments, the method for treating rhodium-containing wastewater by cold plasma glow discharge comprises the following steps:

placing a mixed solution formed by mixing rhodium-containing wastewater and an additive in a plasma discharge gas atmosphere;

under the action of alternating current, rhodium ions in the mixed solution are reduced to form a rhodium simple substance by plasma formed by discharging the plasma discharge gas.

In some embodiments, the ratio of the molar amount of rhodium ions in the rhodium-containing wastewater to the molar amount of the additive is 1 (1-15), preferably 1 (3.5-15).

In some embodiments, the additive comprises 4 to 8mol/L concentrated hydrochloric acid and/or pure perchloric acid.

In some embodiments, the plasma discharge gas comprises one or more of an inert gas, nitrogen, and air.

In some embodiments, the alternating current has a voltage of 150 to 400V, preferably 200 to 300V; the reduction time is 5-15min, preferably 5-13 min.

In some embodiments, the method further comprises:

filtering and washing the product obtained after the discharge treatment to obtain a rhodium metal crude product;

and sequentially roasting and reducing the crude rhodium metal product to obtain rhodium powder.

In some embodiments, the method of washing treatment comprises: and washing with absolute ethyl alcohol and deionized water in sequence.

In some embodiments, the temperature of the roasting treatment is 400 to 800 ℃, preferably 550 to 700 ℃; and/or the time of the roasting treatment is 5.5 to 24.5 hours, preferably 8 to 22 hours.

In some embodiments, the temperature of the reduction treatment is 500 to 1000 ℃, preferably 700 to 900 ℃; and/or the time of the reduction treatment is 4 to 12 hours, preferably 5 to 10 hours.

Compared with the prior art, the invention has the following beneficial effects:

according to the method for recovering rhodium from rhodium-containing wastewater provided by the invention, the rhodium ions in the rhodium-containing wastewater are reduced and separated by adopting a cold plasma glow discharge method, so that the introduction of a large amount of reducing agents is avoided, the recovery process is simplified, and the recovery cost is reduced. Meanwhile, the method also has the advantages of high selectivity and high separability, the recovery rate of rhodium can reach more than 97%, and the purity of the recovered rhodium is more than 99.95%. In addition, the recovery method provided by the invention is simple and does not cause secondary pollution to the environment.

Detailed Description

In order that the present invention may be more readily understood, the following detailed description of the invention is given by way of example only, and is not intended to limit the scope of the invention.

In view of the fact that the traditional method for recovering rhodium from rhodium-containing wastewater has the defects of long process flow and low recovery rate, and the traditional refining method has the defects of high impurity content, high environmental pollution, high cost and the like, repeated experimental research shows that the cold plasma glow discharge technology is applied to the recovery treatment of rhodium, so that the treatment process is simplified, a large amount of reducing agents are not required to be introduced for reducing rhodium ions, the recovery rate of rhodium is high, and the purity of the recovered rhodium is high. The present invention has been made based on the above findings.

Accordingly, the present invention provides a process for recovering rhodium from a spent rhodium catalyst residue comprising the steps of:

s1, carrying out cold plasma glow discharge treatment on the rhodium-containing wastewater to reduce rhodium ions in the rhodium-containing wastewater into a rhodium simple substance;

s2, filtering and washing the product obtained after the discharge treatment to obtain a rhodium metal crude product;

and S3, sequentially roasting and reducing the crude rhodium metal product to obtain rhodium powder.

Specifically, the method for treating the rhodium-containing wastewater by cold plasma glow discharge comprises the following steps:

s11, placing a mixed solution formed by mixing rhodium-containing wastewater and an additive in a plasma discharge gas atmosphere;

and S12, under the action of alternating current, reducing rhodium ions in the mixed solution into a rhodium simple substance by plasma formed by the discharge of the plasma discharge gas.

The rhodium-containing wastewater in the invention contains rhodium metal salt, and the rhodium metal salt comprises chloride of rhodium metal and/or sulfate of rhodium metal. Reducing rhodium ions in rhodium metal salt in the rhodium-containing wastewater into a rhodium simple substance through cold plasma glow discharge treatment.

In step S11, the ratio of the molar amount of rhodium ions in the rhodium-containing wastewater to the molar amount of the additive is 1 (1-15), preferably 1 (3.5-15), more preferably 1 (5-15), still more preferably 1 (6-14), and most preferably 1 (7.5-10).

In step S11, the additive is added to reduce rhodium ions in the solution under glow discharge conditions. Preferably, the additive comprises 4 to 8mol/L concentrated hydrochloric acid and/or pure perchloric acid.

The plasma discharge gas in step S11 of the present invention is a gas plasma capable of generating positive and negative ions under high pressure. The plasma discharge gas comprises one or more of an inert gas, nitrogen and air, preferably an inert gas, more preferably argon. The inventors of the present invention have found that the selectivity and efficiency of the inert gas are higher compared to nitrogen and air because: (1) inert gases and other elements are difficult to form in a stable compound form; (2) inert gas, such as argon, has a high first ionization point, and the formed argon anions exist as electron-rich substances, so that high energy can be provided to act on rhodium ions to reduce the rhodium ions into nano metal rhodium, and finally the argon anions become argon.

In step S12, the voltage of the alternating current is 150-400V, preferably 200-300V; the reduction time is 5-15min, preferably 5-13 min. In the present invention, the discharge voltage (ac voltage) needs to be strictly controlled. Too low discharge voltage can result in weaker reduction reaction and lower rhodium yield; the discharge voltage is too high, so that the requirements on equipment, grounding environment and the like are high, the requirements are difficult to meet in practical application, and the product post-treatment process is difficult due to the too high voltage, the loss of rhodium is caused, and the yield of the noble metal rhodium is influenced.

After the treatment in step S1, since the rhodium simple substance is formed in the solution, in the subsequent step S2, it is necessary to centrifuge and filter the solid-liquid mixture, and wash the cake obtained by the filtration.

In step S2, the method of washing processing includes: and sequentially adopting absolute ethyl alcohol and deionized water for washing until the filtrate is neutral.

In order to further produce the crude rhodium metal into rhodium powder, the crude rhodium metal needs to be further processed.

In step S3, some residual organic matters can be further removed by the baking treatment, and since the baking treatment oxidizes part of the rhodium, a further reduction treatment is required after the baking treatment, and the reduction treatment is also a process for removing impurities. The roasting treatment temperature is 400-800 ℃, preferably 550-700 ℃; and/or the time of the roasting treatment is 5.5 to 24.5 hours, preferably 8 to 22 hours.

In step S3, the temperature of the reduction treatment is 500-1000 ℃, preferably 700-900 ℃; and/or the time of the reduction treatment is 4 to 12 hours, preferably 5 to 10 hours.

The starting materials used in the present invention are commercially available unless otherwise specified.

The operations and treatments involved in the present invention are conventional in the art unless otherwise specified.

The apparatus used in the present invention is an apparatus conventional in the art unless otherwise specified.

The test method or the calculation method provided by the invention is as follows:

the rhodium recovery is calculated as:

rhodium recovery rate ═ rhodium powder mass g × rhodium powder purity ]/(rhodium content in rhodium-containing wastewater mass% × rhodium-containing wastewater mass g) × 100%

The mass percentage of rhodium in the rhodium-containing wastewater is analyzed by ICP (inductively coupled plasma emission spectrometer), and the purity of the rhodium powder is analyzed by ICP after the rhodium powder is electrified and dissolved by concentrated hydrochloric acid (37 wt%).

Examples

Example 1

Will contain H₃RhCl₆、FeCl₃And NiCl₂5.50g of rhodium-containing wastewater (rhodium content: 1.44 wt%, measured by a method of dissolving with 37 wt% concentrated hydrochloric acid) and a mixed solution (H) of hydrochloric acid having a concentration of 4mol/L₃RhCl₆The molar weight ratio of the raw materials to HCl is 1:6), placing the raw materials into a quartz boat, placing the quartz boat into a cold plasma discharger, placing the quartz boat between two electrode plates of a discharge tube in a vacuum chamber, sealing the vacuum chamber, vacuumizing the vacuum chamber, filling argon as discharge gas, applying 150V alternating voltage on the electrodes at normal pressure, reducing rhodium by adopting cold plasma glow discharge for 5min, and collecting a solid-liquid mixture after the reaction is finished. Repeating the experiment for 20 times under the same conditions, centrifuging, standing, filtering the solid-liquid mixture to obtain filter cake, sequentially washing with ethanol and deionized water until pH value is neutral, and oven drying to obtain rhodium metal crude productAnd (5) preparing the product. Heating the rhodium metal crude product to 400 ℃ in a muffle furnace, roasting for 5.5 hours, naturally cooling to room temperature, and grinding to obtain solid powder; subjecting the solid powder to H treatment at 700 deg.C₂Reducing for 4h to obtain 1.56g of high-purity rhodium powder, wherein the recovery rate of rhodium is 98.44 percent, and the purity is 99.95 percent.

Example 2

Will contain Rh₂(SO₄)₃、FeCl₃、Fe₂(SO₄)₃、NiSO₄And NiCl₂5.45g of rhodium-containing wastewater (rhodium content: 1.79 wt%, measured by a method of dissolving with 37 wt% concentrated hydrochloric acid) and a mixed solution of hydrochloric acid (Rh) having a concentration of 4mol/L₂(SO₄)₃The molar weight ratio of the metal halide to HCl is 1:20) is placed into a quartz boat, then the quartz boat is placed into a cold plasma discharger, the quartz boat is placed between two electrode plates of a discharge tube in a vacuum chamber, the quartz boat is sealed, the vacuum chamber is vacuumized, then nitrogen is filled as discharge gas, the alternating voltage of 200V is applied to the electrodes under normal pressure, the cold plasma glow discharge is adopted to reduce rhodium, the reduction time is 12min, and after the reaction is finished, a solid-liquid mixture is collected. And repeating the experiment for 20 times according to the same conditions, centrifuging, standing and filtering the finally collected solid-liquid mixture to obtain a filter cake, washing the filter cake with ethanol and deionized water in sequence until the pH value is neutral, and drying to obtain the crude rhodium metal product. Heating the rhodium metal crude product to 550 ℃ in a muffle furnace, roasting for 8 hours, naturally cooling to room temperature, and grinding to obtain solid powder; subjecting the solid powder to H treatment at 800 deg.C₂Reducing for 5h to obtain 1.90g of high-purity rhodium powder, wherein the recovery rate of the rhodium is 97.33 percent, and the purity is 99.95 percent.

Example 3

Will contain Rh₂(SO₄)₃、Fe₂(SO₄)₃And NiCl₂5.50g of rhodium-containing wastewater (rhodium content: 1.77 wt%, measured by a method of dissolving with 37 wt% concentrated hydrochloric acid) and a mixed solution of hydrochloric acid (Rh) having a concentration of 8mol/L₂(SO₄)₃The molar weight ratio of HCl to HCl is 1:30) is put into a quartz boat and then put into a cold plasma discharger, the quartz boat and the cold plasma discharger are put between two electrode plates of a discharge tube in a vacuum chamber, the vacuum chamber is sealed and vacuumized, and then argon is filled as a discharge gasApplying 200V alternating voltage on an electrode by using electric gas under normal pressure, reducing rhodium by adopting cold plasma glow discharge for 12min, and collecting a solid-liquid mixture after the reaction is finished. And repeating the experiment for 20 times according to the same conditions, centrifuging, standing and filtering the finally collected solid-liquid mixture to obtain a filter cake, washing the filter cake with ethanol and deionized water in sequence until the pH value is neutral, and drying to obtain the crude rhodium metal product. Heating the rhodium metal crude product to 550 ℃ in a muffle furnace, roasting for 12 hours, naturally cooling to room temperature, and grinding to obtain solid powder; subjecting the solid powder to H treatment at 900 deg.C₂Reducing for 6h to obtain 1.89g of high-purity rhodium powder, wherein the recovery rate of rhodium is 97.02 percent, and the purity is 99.95 percent.

Example 4

Will contain Rh₂(SO₄)₃、Fe₂(SO₄)₃And NiSO₄5.50g of rhodium-containing wastewater (rhodium content: 1.96 wt%, measured by a method of dissolving with 37 wt% concentrated hydrochloric acid) and a mixed solution of hydrochloric acid (Rh) having a concentration of 6mol/L₂(SO₄)₃The molar weight ratio of the catalyst to HCl is 1:24) is placed into a quartz boat, then the quartz boat is placed into a cold plasma discharger, the quartz boat is placed between two electrode plates of a discharge tube in a vacuum chamber, the quartz boat is sealed, the vacuum chamber is vacuumized, then air is filled as discharge gas, the alternating voltage of 400V is applied to the electrodes under normal pressure, the rhodium is reduced by cold plasma glow discharge, the reduction time is 15min, and after the reaction is finished, a solid-liquid mixture is collected. And repeating the experiment for 20 times according to the same conditions, centrifuging, standing and filtering the finally collected solid-liquid mixture to obtain a filter cake, washing the filter cake with ethanol and deionized water in sequence until the pH value is neutral, and drying to obtain the crude rhodium metal product. Heating the rhodium metal crude product to 600 ℃ in a muffle furnace, roasting for 24.5 hours, naturally cooling to room temperature, and grinding to obtain solid powder; subjecting the solid powder to H treatment at 500 deg.C₂Reducing for 12h to obtain 2.11g of high-purity rhodium powder, wherein the recovery rate of rhodium is 97.82 percent, and the purity is 99.95 percent.

Example 5

Will contain H₃RhCl₆、FeCl₃And NiCl₂5.45g of rhodium-containing wastewater (rhodium content: 1.93 wt%, using a method of dissolving with 37 wt% concentrated hydrochloric acid)Measured by the method) and a small amount of a mixed solution of pure perchloric acid (H)₃RhCl₆With HClO₄The molar weight ratio of the rhodium to the rhodium is 1:1), placing the quartz boat into a cold plasma discharger, placing the quartz boat between two electrode plates of a discharge tube in a vacuum chamber, sealing the chamber, vacuumizing the vacuum chamber, filling argon as discharge gas, applying 220V alternating voltage on the electrodes under normal pressure, reducing the rhodium by cold plasma glow discharge for 10min, and collecting a solid-liquid mixture after the reaction is finished. And repeating the experiment for 20 times according to the same conditions, centrifuging, standing and filtering the finally collected solid-liquid mixture to obtain a filter cake, washing the filter cake with ethanol and deionized water in sequence until the pH value is neutral, and drying to obtain the crude rhodium metal product. Heating the rhodium metal crude product to 550 ℃ in a muffle furnace, roasting for 8 hours, naturally cooling to room temperature, and grinding to obtain solid powder; subjecting the solid powder to H treatment at 800 deg.C₂Reducing for 8h to obtain 2.05g of high-purity rhodium powder, wherein the recovery rate of the rhodium is 97.40 percent, and the purity is 99.95 percent.

Example 6

Will contain H₃RhCl₆、FeCl₃And NiCl₂5.50g of rhodium-containing wastewater (rhodium content: 1.84 wt%, measured by a method of dissolving with 37 wt% concentrated hydrochloric acid) and a mixed solution (H) of hydrochloric acid having a concentration of 4mol/L and a small amount of pure perchloric acid₃RhCl₆With HCl and HClO₄The ratio of the total molar amount of (A) is 1:3.5, wherein, H₃RhCl₆Molar ratio to HCl of 1:3, H₃RhCl₆With HClO₄The molar weight ratio of the rhodium to the argon is 1:0.5), placing the quartz boat into a cold plasma discharger, placing the quartz boat between two electrode plates of a discharge tube in a vacuum chamber, sealing, vacuumizing the vacuum chamber, filling argon as discharge gas, applying 200V alternating current voltage on the electrodes under normal pressure, reducing the rhodium by cold plasma glow discharge for 9min, and collecting a solid-liquid mixture after the reaction is finished. And repeating the experiment for 20 times according to the same conditions, centrifuging, standing and filtering the finally collected solid-liquid mixture to obtain a filter cake, washing the filter cake with ethanol and deionized water in sequence until the pH value is neutral, and drying to obtain the crude rhodium metal product. Heating the crude rhodium metal in a muffle furnaceRoasting for 6h at 600 ℃, naturally cooling to room temperature, and grinding to obtain solid powder; subjecting the solid powder to H treatment at 800 deg.C₂Reducing for 8h to obtain 1.97g of high-purity rhodium powder, wherein the recovery rate of rhodium is 97.28 percent, and the purity is 99.95 percent.

Example 7

Will contain H₃RhCl₆、Fe₂(SO₄)₃And NiSO₄5.50g of rhodium-containing wastewater (rhodium content: 1.74 wt%, measured by a method of dissolving with 37 wt% concentrated hydrochloric acid) and a mixed solution (H) of hydrochloric acid having a concentration of 4mol/L₃RhCl₆The molar weight ratio of the rhodium to the HCl is 1:8), placing the quartz boat into a cold plasma discharger, placing the quartz boat between two electrode plates of a discharge tube in a vacuum chamber, sealing, vacuumizing the vacuum chamber, filling air as discharge gas, applying 300V alternating current voltage on the electrodes under normal pressure, reducing the rhodium by cold plasma glow discharge for 13min, and collecting a solid-liquid mixture after the reaction is finished. And repeating the experiment for 20 times according to the same conditions, centrifuging, standing and filtering the finally collected solid-liquid mixture to obtain a filter cake, washing the filter cake with ethanol and deionized water in sequence until the pH value is neutral, and drying to obtain the crude rhodium metal product. Heating the rhodium metal crude product to 800 ℃ in a muffle furnace, roasting for 22h, naturally cooling to room temperature, and grinding to obtain solid powder; subjecting the solid powder to H treatment at 1000 deg.C₂Reducing for 4h to obtain 1.88g of high-purity rhodium powder, wherein the recovery rate of rhodium is 98.17 percent, and the purity is 99.95 percent.

Example 8

Will contain H₃RhCl₆、FeCl₃、Fe₂(SO₄)₃And NiSO₄5.50g of rhodium-containing wastewater (rhodium content: 1.91 wt%, measured by a method of dissolving with 37 wt% concentrated hydrochloric acid) and a mixed solution (H) of hydrochloric acid having a concentration of 4mol/L₃RhCl₆The molar weight ratio of the HCl to the quartz is 1:14) is placed in a quartz boat, then the quartz boat is placed in a cold plasma discharger, the quartz boat is placed between two electrode plates of a discharge tube in a vacuum chamber, the quartz boat is sealed, the vacuum chamber is vacuumized, then argon is filled as discharge gas, normal pressure is achieved, 400V alternating current voltage is applied to the electrodes, the cold plasma glow discharge is adopted to reduce rhodium, and the reduction time is 15minAnd after the reaction is finished, collecting the solid-liquid mixture. And repeating the experiment for 20 times according to the same conditions, centrifuging, standing and filtering the finally collected solid-liquid mixture to obtain a filter cake, washing the filter cake with ethanol and deionized water in sequence until the pH value is neutral, and drying to obtain the crude rhodium metal product. Heating the rhodium metal crude product to 700 ℃ in a muffle furnace, roasting for 24 hours, naturally cooling to room temperature, and grinding to obtain solid powder; subjecting the solid powder to H treatment at 800 deg.C₂Reducing for 10h to obtain 2.04g of high-purity rhodium powder, wherein the recovery rate of rhodium is 97.05 percent, and the purity is 99.95 percent.

Example 9

Will contain H₃RhCl₆、FeCl₃、Fe₂(SO₄)₃And NiSO₄5.50g of rhodium-containing wastewater (rhodium content: 1.91 wt%, measured by a method of dissolving with 37 wt% concentrated hydrochloric acid) and a mixed solution (H) of hydrochloric acid having a concentration of 4mol/L₃RhCl₆The molar weight ratio of the metal halide to HCl is 1:14) is placed into a quartz boat, then the quartz boat is placed into a cold plasma discharger, the quartz boat is placed between two electrode plates of a discharge tube in a vacuum chamber, the quartz boat is sealed, the vacuum chamber is vacuumized, then argon is filled as discharge gas, the electrode is applied with 450V alternating current voltage under normal pressure, the cold plasma glow discharge is adopted to reduce rhodium, the reduction time is 15min, and after the reaction is finished, a solid-liquid mixture is collected. And repeating the experiment for 20 times according to the same conditions, centrifuging, standing and filtering the finally collected solid-liquid mixture to obtain a filter cake, washing the filter cake with ethanol and deionized water in sequence until the pH value is neutral, and drying to obtain the crude rhodium metal product. Heating the rhodium metal crude product to 700 ℃ in a muffle furnace, roasting for 24 hours, naturally cooling to room temperature, and grinding to obtain solid powder; subjecting the solid powder to H treatment at 800 deg.C₂Reducing for 10h to obtain 1.92g of high-purity rhodium powder, wherein the recovery rate of the rhodium is 91.34 percent, and the purity is 99.95 percent.

The embodiment shows that the recovery rate of rhodium can reach more than 97%, the purity of the recovered rhodium is more than 99.95%, and better effect is achieved. Therefore, the invention provides a method for efficiently, greenly and economically recovering rhodium, and the method has wide industrial application prospect.

It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.