Method for recovering platinum from nickel-platinum alloy

Abstract

The invention belongs to the technical field of metal recovery, and discloses a method for recovering platinum from nickel-platinum alloy, which comprises the following steps: step 1, sequentially carrying out acid leaching and filtering treatment on the nickel-platinum alloy to obtain platinum-containing filter residues; 2, the platinum-containing filter residues are subjected to leaching treatment through aqua regia to obtain platinum-containing aqua regia liquid, and then the platinum-containing aqua regia liquid is subjected to nitrate removal treatment to obtain treatment liquid; 3, iron powder is added into the treating fluid, an ultrasonic vibration rod is adopted for a replacement reaction, and then coarse platinum slag is obtained through filtering; 4, the crude platinum slag is sequentially subjected to acid leaching, filtering and drying, and sponge platinum is obtained; wherein the adding amount of the iron powder in the step 3 is 25-30 times of the weight of platinum in the platinum-containing filter residues, and the pH value of the system is maintained to be 1-3 in the replacement reaction process. According to the method, the iron powder is adopted for replacing platinum in the treating fluid, platinum in the treating fluid is reduced, nickel in the treating fluid cannot be replaced together, the nickel and platinum separation effect is excellent, hydrazine hydrate does not need to be adopted subsequently, the platinum recovery rate is high, and meanwhile environmental pollution is small.

Description

Technical Field

[0001] The invention relates to the technical field of metal recovery, and in particular to a method for recovering platinum from a nickel-platinum alloy. Background Art

[0002] In recent years, with the rapid development of the semiconductor industry, nickel-platinum alloy targets, as an important material, are mainly used in diode and integrated circuit coating in the semiconductor industry. With the production and use of targets, the waste liquid in the production process and after use increases year by year, mainly including scraps generated during mechanical processing and contaminated high-purity residual targets. Therefore, it is necessary to recover metals from such nickel-platinum alloy target waste or scraps.

[0003] The current method for recycling platinum alloy waste in the industry is: the platinum-containing waste is directly dissolved in aqua regia, and the insoluble residue is filtered out, ammonium chloride is added to the solution to form ammonium chloroplatinate precipitate, and finally the ammonium chloroplatinate is reduced with hydrazine hydrate or calcined to recover sponge platinum; such as prior art 1: Chinese patent application 202410248860.0 discloses a method for recovering platinum group metals from platinum group-containing alloys, wherein aluminum is used as a fragmentation agent, and the mixture is mixed with the platinum group-containing alloy and first melted in an inert atmosphere, and then cast under vacuum conditions, and then the aluminum is removed with acid, thereby achieving fragmentation of the platinum group-containing alloy, so that the platinum group elements contained therein can be better dissolved in aqua regia; thereafter, the platinum group metals are effectively purified and recovered through aqua regia dissolution, ammonium chloride precipitation, sodium sulfite reduction, hydrogen peroxide oxidation and hydrazine hydrate reduction, without the need for capture metals, lower costs and shorter process flow.

[0004] The above-mentioned prior art 1 is to use ammonium chloride to dissolve the platinum-containing aqua regia liquid after dissolving the aqua regia to precipitate the platinum element, produce ammonium chloroplatinate, and then use hydrazine hydrate reduction. Although the process uses sodium sulfite reduction and hydrogen peroxide oxidation to improve the dissolution and precipitation effects of the platinum element, the method of hydrazine hydrate reduction is ultimately used. The pollution to the environment is large and the process is complicated. If this method is used to recover platinum from a large amount of nickel-platinum alloy waste targets or scraps, it will cause a large environmental control cost, and the complex process is easy to cause improper control during large-scale recovery, resulting in a decrease in the recovery rate. Summary of the invention

[0005] One of the purposes of the present invention is to provide a method for recovering platinum from a nickel-platinum alloy. Compared with the prior art, the method does not use ammonium chloride to precipitate the platinum element, thereby avoiding subsequent operations such as hydrazine hydrate reduction, which are complex in process and cause great environmental pollution. The method has the advantage of a high recovery rate when used for recovering platinum from a large amount of nickel-platinum alloy waste.

[0006] To achieve the above object, the present invention provides a method for recovering platinum from a nickel-platinum alloy, comprising the following steps:

[0007] Step 1: acid leaching and filtering the nickel-platinum alloy in sequence to obtain a platinum-containing filter residue;

[0008] Step 2: treating the platinum-containing filter residue with aqua regia leaching to obtain a platinum-containing aqua regia liquid, and then performing a nitrate removal treatment on the platinum-containing aqua regia liquid to obtain a treated liquid;

[0009] Step 3: adding iron powder to the treatment solution and using an ultrasonic vibrating rod to perform a replacement reaction, and then filtering to obtain a crude platinum slag;

[0010] Step 4: acid leaching, filtering and drying the crude platinum slag in sequence to obtain sponge platinum;

[0011] The amount of iron powder added in step 3 is 25-30 times the weight of platinum in the platinum-containing filter residue, and the pH of the system is maintained between 1-3 during the replacement reaction.

[0012] Preferably, the nickel-platinum alloy is a nickel-platinum alloy in block, flake or powder form.

[0013] More preferably, the size of the nickel-platinum alloy is preferably a nickel-platinum alloy with a length, width and height all less than 2 cm.

[0014] Preferably, the specific operation of step 1 is: adding the nickel-platinum alloy to a 30% dilute sulfuric acid solution and continuously stirring at a temperature of 80-100° C. for 6-8 hours, and then centrifugally filtering and separating using a tubular centrifuge to obtain a platinum-containing filter residue; wherein the solid-liquid ratio of the nickel-platinum alloy to the dilute sulfuric acid solution is 1g:2-10ml.

[0015] More preferably, the rotation speed of the tubular centrifuge in step 1 is 15000 r / min, the separation factor is 15000G, and the centrifugal speed is 0.5-1 min / L, which can effectively improve the efficiency of solid-liquid separation.

[0016] Preferably, the specific operation of step 2 is: adding the platinum-containing filter residue into aqua regia, leaching at a temperature of 80-90°C for 1-2h to obtain a platinum-containing aqua regia liquid, and then adding formic acid to the platinum-containing aqua regia liquid at a temperature of 95-100°C to control the redox potential at 500-600mV to perform a nitrate removal treatment to obtain a treated liquid.

[0017] Furthermore, the aqua regia is aqua regia with a volume ratio of 36wt% hydrochloric acid: 68wt% nitric acid = 3:1, the solid-liquid ratio of the platinum-containing filter residue to the aqua regia is 1g:7-8ml; the mass of the formic acid is 1-1.5 times the mass of the nitric acid in the aqua regia.

[0018] Compared with the conventional technology of using concentrated hydrochloric acid to remove nitrate, the present invention uses formic acid to remove nitrate, which does not produce waste gas such as chlorine, and further reduces environmental pollution.

[0019] Preferably, the specific operation of step 3 is: heating the treatment liquid to 60-80°C, then adding iron powder and vibrating with an ultrasonic vibrator for a replacement reaction for 1-2 hours, adding concentrated hydrochloric acid to the solution during the replacement reaction to maintain the pH of the solution between 1-3, and after the replacement reaction is completed, filtering to obtain crude platinum slag.

[0020] Since iron powder reacts with hydrochloric acid during the replacement reaction, consuming the acidity of the solution to generate hydrogen, causing the pH of the solution to slowly increase, it is necessary to maintain the pH environment of the replacement reaction by adding concentrated hydrochloric acid.

[0021] Preferably, the specific operation of step 4 is: adding 6 mol / L dilute hydrochloric acid to the crude platinum slag for acid leaching at a temperature of 80-100°C for 1-2 hours, and then filtering and drying in sequence to obtain sponge platinum; the solid-liquid ratio of the crude platinum slag to the dilute hydrochloric acid is 1g:3-4ml.

[0022] Preferably, the filtration in step 3 and step 4 is performed using a polypropylene microporous membrane filter.

[0023] Preferably, the iron powder has a purity of 4N or above, and a particle size of the iron powder is ≤0.5 μm.

[0024] The present invention adopts iron powder with a purity of 4N or above, and its impurities are only copper, aluminum, manganese and silicon, and the content is extremely small, which can reduce the introduction of some sulfuric acid insolubles, and ensure that the replaced platinum powder will not introduce excessive copper, manganese, aluminum, silicon and other elements; and the particle size of the iron powder is ≤0.5μm, which can effectively reduce the replacement and impurity removal time.

[0025] Beneficial Effects

[0026] Compared with the prior art, the present invention has at least the following advantages:

[0027] (1) The present invention uses iron powder to replace the platinum in the treatment solution, reduces the platinum in the treatment solution and does not replace the nickel in the treatment solution together, has an excellent effect of separating nickel and platinum, and does not need to use hydrazine hydrate subsequently, has a high platinum recovery rate and low environmental pollution;

[0028] (2) In the process of the replacement reaction in step 3 of the present invention, the pH environment is maintained, which can effectively improve the recovery rate of platinum;

[0029] (3) The present invention uses excess iron powder to replace the platinum in the treatment solution, and is equipped with an ultrasonic vibration rod to promote the replacement reaction. The ultrasonic vibration allows the iron powder floating on the treatment solution to fully enter the treatment solution to complete the replacement reaction, thereby improving the recovery rate of platinum. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the embodiments, but it does not constitute any limitation to the present invention. Any limited number of modifications made within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0031] In order to explain the technical content of the present invention in detail, further description is given below in conjunction with the implementation modes.

[0032] In the following examples and comparative examples, the aqua regia is aqua regia with a volume ratio of 36wt% hydrochloric acid: 68wt% nitric acid = 3:1; the speed of the tubular centrifuge is 15000r / min, the separation factor is 15000G, and the centrifugal speed is 1min / L; the iron powder with a purity of 99.99% has a particle size of ≤0.5μm;

[0033] In the following examples and comparative examples, the nickel-platinum alloy is a square nickel-platinum alloy with a size of 1 cm*1 cm*1 cm, and the platinum content in the nickel-platinum alloy is detected by XRF before recovery; the platinum content in the alloy block and the platinum-containing filter residue is detected and calculated by XRF, and the purity of sponge platinum is obtained by GDMS detection.

[0034] Example 1

[0035] A method for recovering platinum from a nickel-platinum alloy comprises the following steps:

[0036] Step 1: adding the nickel-platinum alloy to a 30% dilute sulfuric acid solution and continuously stirring at a temperature of 85° C. for 7 hours, and then centrifugally filtering and separating the platinum-containing filter residue using a tubular centrifuge; wherein the solid-liquid ratio of the nickel-platinum alloy to the dilute sulfuric acid solution is 1 g:5 ml, and after XRF detection, the platinum content of the platinum-containing filter residue is 10.54 g;

[0037] Step 2: Add the platinum-containing filter residue to aqua regia, leach at 85°C for 2h to obtain a platinum-containing aqua regia liquid, then add formic acid at 100°C to control the redox potential at 550mV to perform a nitrate removal treatment to obtain a treated liquid, the solid-liquid ratio of the platinum-containing filter residue to the aqua regia is 1g:7ml; the mass of the formic acid is 1.5 times the mass of the nitric acid in the aqua regia;

[0038] Step 3: Heat the treatment solution to 75°C, then add iron powder and vibrate with an ultrasonic vibrator for a replacement reaction for 2 hours. During the replacement reaction, use concentrated hydrochloric acid to maintain the pH between 2±0.5. After the replacement reaction is completed, filter to obtain crude platinum slag. The amount of iron powder added is 25 times the weight of platinum in the platinum-containing filter residue;

[0039] Step 4: Add 6 mol / L dilute hydrochloric acid to the crude platinum slag and acid-leach at 90°C for 2 hours, then filter and dry in sequence to obtain sponge platinum; the solid-liquid ratio of the crude platinum slag to the dilute hydrochloric acid is 1g:3ml.

[0040] Example 2

[0041] A method for recovering platinum from a nickel-platinum alloy comprises the following steps:

[0042] Step 1: adding the nickel-platinum alloy to a 30% dilute sulfuric acid solution and continuously stirring at a temperature of 85° C. for 7 hours, and then centrifugally filtering and separating the platinum-containing filter residue using a tubular centrifuge; wherein the solid-liquid ratio of the nickel-platinum alloy to the dilute sulfuric acid solution is 1 g:10 ml, and after XRF detection, the platinum content of the platinum-containing filter residue is 10.87 g;

[0043] Step 2: Add the platinum-containing filter residue to aqua regia, leaching at 85°C for 2h to obtain a platinum-containing aqua regia liquid, then add formic acid at 100°C to control the redox potential at 550mV to perform a nitrate removal treatment to obtain a treated liquid, the solid-liquid ratio of the platinum-containing filter residue to the aqua regia is 1g:8ml; the mass of the formic acid is 1.5 times the mass of the nitric acid in the aqua regia;

[0044] Step 3: Heat the treatment liquid to 75°C, then add iron powder and vibrate with an ultrasonic vibrator for 2 hours to perform a replacement reaction. During the replacement reaction, use concentrated hydrochloric acid to maintain the pH between 2±0.5. After the replacement reaction is completed, filter to obtain a crude platinum slag. The amount of iron powder added is 28 times the weight of platinum in the platinum-containing filter residue;

[0045] Step 4: Add 6 mol / L dilute hydrochloric acid to the crude platinum slag and acid-leach at 90°C for 2 hours, then filter and dry in sequence to obtain sponge platinum; the solid-liquid ratio of the crude platinum slag to the dilute hydrochloric acid is 1g:3ml.

[0046] Example 3

[0047] A method for recovering platinum from a nickel-platinum alloy comprises the following steps:

[0048] Step 1: adding the nickel-platinum alloy to a 30% dilute sulfuric acid solution and continuously stirring at a temperature of 85° C. for 7 hours, and then centrifugally filtering and separating the platinum-containing filter residue using a tubular centrifuge; wherein the solid-liquid ratio of the nickel-platinum alloy to the dilute sulfuric acid solution is 1 g:5 ml, and after XRF detection, the platinum content of the platinum-containing filter residue is 8.15 g;

[0049] Step 2: Add the platinum-containing filter residue to aqua regia, leach at 85°C for 2h to obtain a platinum-containing aqua regia liquid, then add formic acid at 100°C to control the redox potential at 550mV to perform a nitrate removal treatment to obtain a treated liquid, the solid-liquid ratio of the platinum-containing filter residue to the aqua regia is 1g:7ml; the mass of the formic acid is 1.5 times the mass of the nitric acid in the aqua regia;

[0050] Step 3: Heat the treatment liquid to 75°C, then add iron powder and vibrate with an ultrasonic vibrator for 2 hours to perform a replacement reaction. During the replacement reaction, use concentrated hydrochloric acid to maintain the pH between 2±0.5. After the replacement reaction is completed, filter to obtain a crude platinum slag. The amount of iron powder added is 30 times the weight of platinum in the platinum-containing filter residue;

[0051] Step 4: Add 6 mol / L dilute hydrochloric acid to the crude platinum slag and acid-leach at 90°C for 2 hours, then filter and dry in sequence to obtain sponge platinum; the solid-liquid ratio of the crude platinum slag to the dilute hydrochloric acid is 1g:3ml.

[0052] Comparative Example 1

[0053] It is generally the same as Example 1, except that the platinum content of the platinum-containing residue obtained in step 1 is 10.11 g, and the pH value is not maintained in step 3.

[0054] Comparative Example 2

[0055] It is generally the same as Example 1, except that the platinum content of the platinum-containing residue obtained in step 1 is 10.70 g, and the amount of iron powder added in step 3 is 18 times the weight of platinum in the platinum-containing residue.

[0056] Comparative Example 3

[0057] It is generally the same as Example 1, except that in step 3, instead of using ultrasonic vibration rod vibration to carry out the replacement reaction, stirring is used to carry out the replacement reaction.

[0058] Finally, the platinum content of the sponge platinum in Example 1-3 and Comparative Example 1-3 was tested, and the platinum recovery rate was calculated based on the platinum content in the nickel-platinum alloy used in Example 1-3 and Comparative Example 1-2. The results are shown in Table 1.

[0059] Table 1 Platinum recovery results of Examples 1-3 and Comparative Examples 1-3

[0060]

[0061]

[0062] According to the results in Table 1, we can see that:

[0063] According to the data of Examples 1-3, it can be seen that the use of the technical solution of the present invention to recover platinum can achieve an extremely high platinum recovery rate. A comparison of the data of Example 1, Example 2 and Example 3 shows that the purity of the sponge platinum obtained in Example 1 reaches the 4N standard. It may be that the excessive amount of iron powder used may result in incomplete acid leaching and removal of some iron elements, affecting the purity of the platinum.

[0064] According to the data comparison between Example 1 and Comparative Example 1, in the process of replacing platinum with iron powder, the control of pH has a greater impact on the replacement reaction. If the pH value is not controlled, the recovery rate of platinum will be greatly reduced and the purity of the recovered sponge platinum will be low.

[0065] Although the purity of sponge platinum reaches 4N in Comparative Example 2, the platinum recovery rate is only 87.01%, and the loss is large, indicating that the amount of Fe powder added is insufficient, and part of the platinum in the solution has not been replaced; Comparative Example 3 has the same purity as Comparative Example 2, and the platinum recovery rate is higher than that of Comparative Example 2, which is 90.31%, but 9.69% of the platinum remains in the solution and is not recovered, indicating that the use of normal stirring for the replacement reaction will cause some Fe to fail to react with Pt, thereby reducing the recovery rate.

[0066] The embodiments presented herein are only embodiments selected according to the combination of all possible embodiments. The appended claims should not be limited by the embodiments describing the present invention. Some numerical ranges used in the claims include sub-ranges therein, and the changes in these ranges should also be covered by the appended claims.

Claims

1. A method for recovering platinum from a nickel-platinum alloy, characterized in that: The steps include: Step 1: acid leaching and filtering the nickel-platinum alloy in sequence to obtain a platinum-containing filter residue; Step 2: treating the platinum-containing filter residue with aqua regia leaching to obtain a platinum-containing aqua regia liquid, and then performing a nitrate removal treatment on the platinum-containing aqua regia liquid to obtain a treated liquid; Step 3: adding iron powder to the treatment solution and using an ultrasonic vibrating rod to perform a replacement reaction, and then filtering to obtain a crude platinum slag; Step 4: acid leaching, filtering and drying the crude platinum slag in sequence to obtain sponge platinum; The amount of iron powder added in step 3 is 25-30 times the weight of platinum in the platinum-containing filter residue, and the pH of the system is maintained between 1-3 during the replacement reaction.

2. The method for recovering platinum from a nickel-platinum alloy according to claim 1, characterized in that: The specific operation of step 1 is: adding the nickel-platinum alloy to a dilute sulfuric acid solution with a concentration of 30%, stirring continuously at a temperature of 80-100° C. for 6-8 hours, and then centrifugally filtering and separating using a tubular centrifuge to obtain a platinum-containing filter residue; wherein the solid-liquid ratio of the nickel-platinum alloy to the dilute sulfuric acid solution is 1g:2-10ml.

3. The method for recovering platinum from a nickel-platinum alloy according to claim 1, characterized in that: The specific operation of step 2 is: adding the platinum-containing filter residue into aqua regia, leaching at a temperature of 80-90°C for 1-2h to obtain a platinum-containing aqua regia liquid, and then adding formic acid to the platinum-containing aqua regia liquid at a temperature of 95-100°C to control the redox potential at 500-600mV to perform a nitrate removal treatment to obtain a treated liquid.

4. The method for recovering platinum from a nickel-platinum alloy according to claim 3, characterized in that: The aqua regia is aqua regia with a volume ratio of 36wt% hydrochloric acid: 68wt% nitric acid = 3:1, and the solid-liquid ratio of the platinum-containing filter residue to the aqua regia is 1g:7-8ml; the mass of the formic acid is 1-1.5 times the mass of the nitric acid in the aqua regia.

5. The method for recovering platinum from a nickel-platinum alloy according to claim 1, characterized in that: The specific operation of step 3 is: heating the treatment liquid to 60-80° C., then adding iron powder and vibrating with an ultrasonic vibrator for a replacement reaction for 1-2 hours, adding concentrated hydrochloric acid to the solution during the replacement reaction to maintain the pH of the solution between 1-3, and filtering to obtain crude platinum slag after the replacement reaction is completed.

6. The method for recovering platinum from a nickel-platinum alloy according to claim 1, characterized in that: The specific operation of step 4 is: adding 6 mol / L dilute hydrochloric acid to the crude platinum slag for acid leaching at 80-100°C for 1-2 hours, and then filtering and drying in sequence to obtain sponge platinum; the solid-liquid ratio of the crude platinum slag to the dilute hydrochloric acid is 1g:3-4ml.

7. The method for recovering platinum from a nickel-platinum alloy according to claim 1, characterized in that: The filtration in step 3 and step 4 is performed by filtration with a polypropylene microporous membrane.

8. The method for recovering platinum from a nickel-platinum alloy according to claim 1, characterized in that: The nickel-platinum alloy is a nickel-platinum alloy in block, sheet or powder form.

9. The method for recovering platinum from a nickel-platinum alloy according to claim 1, characterized in that: The iron powder has a purity of 4N or above, and a particle size of the iron powder is ≤0.5 μm.

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