Method for removing potassium ions in chloroiridic acid solution

Abstract

The invention discloses a method for removing potassium ions in a chloroplatinic acid solution. The method comprises the following steps: 1, adding sponge platinum into heated aqua regia to obtain a chloroplatinic acid solution; 2, adding a reducing agent A into the chloroiridic acid solution for reduction; 3, adding a chloroplatinic acid solution into the reduction solution for reaction; 4, filtering, adding an oxidizing agent B, and adding NH4Cl for oxidation reaction to obtain a precipitate; and 5, placing the precipitate in aqua regia, heating, dissolving and breaking ammonium. The valence state and potential of iridium ions in the chloroiridic acid solution are adjusted through the reduction reaction, the solubility of the potassium chloroiridate is changed, then the chloroplatinic acid solution potassium removal agent is added to react with the potassium chloroiridate (III) acid, and the potassium ions in the chloroiridate (III) acid solution are removed through the difference of the solubility of the potassium removal agent and the solubility of the potassium chloroiridate (III) acid in the solution. And the method is simple, convenient and efficient, effectively shortens the period of a later impurity removal process, and saves the production cost.

Description

Technical Field

[0001] The invention belongs to the technical field of purification of precious metal products, and in particular relates to a method for removing potassium ions from a chloroiridic acid solution. Background Art

[0002] Iridium (Ir), a member of the platinum group, is one of the densest and most corrosion-resistant elements known on Earth. It is mainly used in chemical catalysts, corrosion-resistant coatings, electronic equipment, precision instruments, and aerospace fields. These characteristics and applications of iridium demonstrate its importance as a unique metal in modern science and industry. Although the use of iridium and its chemical products is limited by their scarcity and high price, it is still an irreplaceable material in some key applications. Among them, H2IrCl6 is an important intermediate product for the preparation of other Ir chemical products and its status is very important. Therefore, the purity of H2IrCl6 determines the purity of other iridium chemical products as well as the quality and production efficiency of downstream products.

[0003] At present, when preparing H2IrCl6, due to factors such as the usage scenarios of H2IrCl6 raw materials, the source of materials, and the purity of chemical reagents used in the front-end process, potassium enters the iridium-containing solution and accumulates continuously, resulting in a large amount of potassium gathering in the H2IrCl6 solution, and the subsequent concentration of the H2IrCl6 solution ultimately leads to a high enrichment of potassium in the H2IrCl6 solution product. In the 2022 national standard, although there are no relevant requirements for the content of potassium ions in the H2IrCl6 product, excessive potassium ion impurity content in the H2IrCl6 solution will cause a certain amount of potassium chloroiridate precipitate to exist in the solution, thereby reducing the purity of the product, resulting in a decline in product quality and performance, and ultimately causing adverse effects on later production.

[0004] In the patent with application number 202211375012.3, the crude ammonium chloroiridate, water and reducing agent are reacted and filtered through a microporous filter membrane, and the filtrate is reacted with an oxidant to obtain high-purity ammonium chloroiridate, thereby preparing high-quality H2IrCl6. This process seriously affects the service life and performance of the membrane due to the acid environment. At the same time, the microporous filter membrane will entrain some iridium during filtration, resulting in a loss of iridium content.

[0005] Therefore, developing a method for purifying and producing high-quality H2IrCl6 has good application prospects. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method for removing potassium ions from a chloroiridic acid solution in view of the above-mentioned deficiencies in the prior art. The method adjusts the valence and potential of iridium ions in the chloroiridic acid solution by a reduction reaction, changes the solubility of potassium chloroiridate, and then adds a chloroplatinic acid solution potassium remover to react with potassium chloroiridate (III) to generate a potassium-containing precipitate, thereby removing potassium ions from the chloroiridic acid (III) solution, obtaining a high-purity chloroiridic acid (IV) solution, and solving the problem that potassium impurities in the chloroiridic acid are relatively high, resulting in reduced product quality and performance.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is: a method for removing potassium ions from a chloroiridic acid solution, characterized in that the method comprises the following steps:

[0008] Step 1, adding sponge platinum to the heated aqua regia in small amounts several times, and boiling to promote the dissolution of the sponge platinum until the solution is clear and free of filter residues, cooling and filtering to obtain a chloroplatinic acid solution as a potassium removal agent;

[0009] Step 2: adding a reducing agent A to the chloroiridic acid solution for reduction, so that Ir(IV) is converted into Ir(III) to obtain a reduced solution;

[0010] Step 3: according to the potassium ion content of the reducing solution in step 2, add the chloroplatinic acid solution in step 1 to the reducing solution, and keep the temperature at 20° C. to 40° C. and stir the reaction for 2 h to 4 h to obtain a mixed solution;

[0011] Step 4: Filter the mixed solution in step 3, add oxidant B to the filtrate, heat it to 90°C to 95°C, add NH4Cl and carry out oxidation reaction at constant temperature for 2h to 4h to obtain (NH4)2IrCl6 precipitate;

[0012] Step 5: Place the (NH4)2IrCl6 precipitate obtained in step 4 in aqua regia and heat to dissolve the broken ammonium to obtain H2IrCl6 solution, and concentrate the H2IrCl6 solution to an Ir mass content of 35%±0.3% according to the YS / T 595-2022 "Chloroiridic Acid" standard.

[0013] The present invention first uses a reducing agent A to reduce chloroiridic acid, adjusts the valence state of iridium ions and changes the potential in the solution, thereby increasing the solubility of potassium chloroiridate (III), then adds a chloroplatinic acid solution as a potassium removing agent to react with potassium chloroiridate (III) to generate an insoluble K2PtCl6 precipitate, and then filters the K2PtCl6 to achieve K + The removal of ions to obtain the filtrate of H3IrCl6 involves the reaction mechanism shown in the following reaction equations (1) and (2):

[0014] 2K ++H2PtCl6→K2PtCl6↓+2H + (1)

[0015] 2K3IrCl6+3H2PtCl6→3K2PtCl6↓+2H3IrCl6 (2)

[0016] Next, the present invention adds oxidant B and NH4Cl to the filtrate of H3IrCl6 to carry out an oxidation reaction, so that Ir(III) is converted into Ir(IV), and a (NH4)2IrCl6 precipitate is obtained, which is then placed in aqua regia and heated to dissolve the broken ammonium to obtain a H2IrCl6 solution, and the H2IrCl6 solution is concentrated to an Ir mass content of 35%±0.3% according to the YS / T 595-2022 "Chloroiridic Acid" standard, so that the purity of the H2IrCl6 product meets the YS / T595-2022 "Chloroiridic Acid" standard.

[0017] The above method for removing potassium ions from a chloroiridic acid solution is characterized in that the reducing agent A in step 2 is at least one of oxalic acid, formic acid, hydrazine hydrate and sodium sulfite. More preferably, the reducing agent A is a hydrazine hydrate solution with a concentration of 50%.

[0018] The above-mentioned method for removing potassium ions from a chloroiridic acid solution is characterized in that the potential of the solution system after the reduction reaction in step 2 is 400mV±30mV.

[0019] The method for removing potassium ions from a chloroiridic acid solution is characterized in that the molar ratio of potassium ions in the reducing solution to platinum ions in the chloroplatinic acid solution in step 3 is n(K + ): n(Pt(VI))=2:0.5~1.5.

[0020] The above method for removing potassium ions from a chloroiridic acid solution is characterized in that the oxidant B in step 4 is at least one of hydrogen peroxide, sodium chlorate and chlorine. More preferably, the oxidant B is a 30% hydrogen peroxide solution.

[0021] The above-mentioned method for removing potassium ions from a chloroiridic acid solution is characterized in that the potential of the solution system after the oxidation reaction in step 4 is 750mV±30mV.

[0022] The above-mentioned method for removing potassium ions from a chloroiridic acid solution is characterized in that the constant temperature condition in step 4 is 90°C±5°C.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. The present invention first adjusts the valence and potential of iridium ions in a chloroiridic acid solution by a reduction reaction to change the solubility of potassium chloroiridate, then adds a chloroplatinic acid solution potassium remover to react with potassium chloroiridate (III), and utilizes the difference in solubility between the potassium remover and potassium chloroiridate (III) in the liquid to remove potassium ions in the chloroiridic acid solution, thereby obtaining a high-purity chloroiridic acid (IV) solution.

[0025] 2. The present invention adds oxidant B and NH4Cl to the filtrate of H3IrCl6 after potassium removal to carry out oxidation reaction to obtain (NH4)2IrCl6 precipitate, while converting Ir(III) into Ir(IV), separating it in the form of (NH4)2IrCl6 precipitate, and converting it into chloroiridic acid solution through subsequent dissolution and ammonium breaking, thereby avoiding the presence of potassium ions or K2PtCl6 precipitates in the filtrate in the chloroiridic acid solution, and further improving the purity of the chloroiridic acid solution.

[0026] 3. The method of the present invention is simple, convenient and efficient, and can achieve one-time removal of potassium ions in H2IrCl6 solution, with a potassium removal rate of more than 99%. In addition, the iridium content in the solution is high and easy to recover, which shortens the subsequent impurity removal process cycle and saves production costs.

[0027] 4. The H2IrCl6 subsequently prepared from the chloroiridic acid solution obtained by the present invention has high purity and quality better than the industry standard YS / T 595-2022 "Chloroiridic Acid", and is suitable for industrial production.

[0028] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The present invention is a schematic diagram of the process of removing potassium ions from the chloroiridic acid solution. DETAILED DESCRIPTION

[0030] Example 1

[0031] like Figure 1 As shown, this embodiment includes the following steps:

[0032] Step 1, adding sponge platinum to the heated aqua regia in small amounts several times, and boiling to promote the dissolution of the sponge platinum until the solution is clear and free of filter residues, and concentrating to a Pt mass content of 37%, and then cooling and filtering to obtain a chloroplatinic acid solution as a potassium removal agent;

[0033] Step 2: Add reducing agent A, i.e., 50% hydrated hydrazine solution, to 1200 g of chloroiridic acid solution containing 0.5% potassium ion concentration for reduction, so that Ir(IV) is converted into Ir(III) to obtain a reduced solution; the potential of the solution system after the reduction reaction is 400 mV±30 mV;

[0034] Step 3: According to the potassium ion content of the reducing solution in step 2, 30 g of the chloroplatinic acid solution in step 1 is slowly added to the reducing solution, and the temperature is maintained at 40 ° C. and stirred for 4 hours to obtain a mixed solution;

[0035] Step 4: Filter the mixed solution in step 3, add oxidant B, i.e., 30% hydrogen peroxide solution, to the filtrate, and then place it on a temperature-controlled heating furnace and heat it to 90°C, then add 350g of NH4Cl and perform oxidation reaction at a constant temperature of 90°C to 95°C for 4h to obtain (NH4)2IrCl6 precipitate; the potential of the solution system after the oxidation reaction is 750mV±30mV;

[0036] Step 5. Place the (NH4)2IrCl6 precipitate obtained in step 4 in aqua regia and heat to dissolve the broken ammonium to obtain H2IrCl6 solution, and concentrate the H2IrCl6 solution to an Ir mass content of 35%±0.3% in accordance with the YS / T 595-2022 "Chloroiridic Acid" standard, and the purity of the H2IrCl6 product meets the YS / T595-2022 "Chloroiridic Acid" standard.

[0037] After testing, the potassium ion concentration in the chloroiridic acid solution after potassium removal in this embodiment was reduced from 0.5% to about 0.14%, K + The removal rate reached 73%.

[0038] The reducing agent A in this embodiment can also be replaced by at least one of oxalic acid, formic acid, hydrazine hydrate and sodium sulfite other than hydrazine hydrate solution; the oxidizing agent B can also be replaced by at least one of hydrogen peroxide, sodium chlorate and chlorine gas other than hydrogen peroxide solution.

[0039] Example 2

[0040] like Figure 1 As shown, this embodiment includes the following steps:

[0041] Step 1, adding sponge platinum to the heated aqua regia in small amounts several times, and boiling to promote the dissolution of the sponge platinum until the solution is clear and free of filter residues, and concentrating to a Pt mass content of 37%, and then cooling and filtering to obtain a chloroplatinic acid solution as a potassium removal agent;

[0042] Step 2: Add reducing agent A, i.e., 50% hydrated hydrazine solution, to 1200 g of chloroiridic acid solution containing 0.5% potassium ion concentration for reduction, so that Ir(IV) is converted into Ir(III) to obtain a reduced solution; the potential of the solution system after the reduction reaction is 400 mV±30 mV;

[0043] Step 3: According to the potassium ion content of the reducing solution in step 2, 36 g of the chloroplatinic acid solution in step 1 is slowly added to the reducing solution, and the temperature is maintained at 20 ° C. and stirred for 3 hours to obtain a mixed solution;

[0044] Step 4: Filter the mixed solution in step 3, add oxidant B, i.e., 30% hydrogen peroxide solution, to the filtrate, and then place it on a temperature-controlled heating furnace and heat it to 90°C, then add 350g of NH4Cl and perform oxidation reaction at a constant temperature of 90°C to 95°C for 3h to obtain (NH4)2IrCl6 precipitate; the potential of the solution system after the oxidation reaction is 750mV±30mV;

[0045] Step 5. Place the (NH4)2IrCl6 precipitate obtained in step 4 in aqua regia and heat to dissolve the broken ammonium to obtain H2IrCl6 solution, and concentrate the H2IrCl6 solution to an Ir mass content of 35%±0.3% in accordance with the YS / T 595-2022 "Chloroiridic Acid" standard, and the purity of the H2IrCl6 product meets the YS / T595-2022 "Chloroiridic Acid" standard.

[0046] After testing, the potassium ion concentration in the chloroiridic acid solution after potassium removal in this embodiment was reduced from 0.5% to about 0.08%, K + The removal rate reached 84.0%.

[0047] The reducing agent A in this embodiment can also be replaced by at least one of oxalic acid, formic acid, hydrazine hydrate and sodium sulfite other than hydrazine hydrate solution; the oxidizing agent B can also be replaced by at least one of hydrogen peroxide, sodium chlorate and chlorine gas other than hydrogen peroxide solution.

[0048] Example 3

[0049] like Figure 1 As shown, this embodiment includes the following steps:

[0050] Step 1, adding sponge platinum to the heated aqua regia in small amounts several times, and boiling to promote the dissolution of the sponge platinum until the solution is clear and free of filter residues, and concentrating to a Pt mass content of 37%, and then cooling and filtering to obtain a chloroplatinic acid solution as a potassium removal agent;

[0051] Step 2: Add reducing agent A, i.e., 50% hydrated hydrazine solution, to 1200 g of chloroiridic acid solution containing 0.5% potassium ion concentration for reduction, so that Ir(IV) is converted into Ir(III) to obtain a reduced solution; the potential of the solution system after the reduction reaction is 400 mV±30 mV;

[0052] Step 3: According to the potassium ion content of the reducing solution in step 2, 45 g of the chloroplatinic acid solution in step 1 is slowly added to the reducing solution, and the temperature is maintained at 20 ° C. and stirred for 3 hours to obtain a mixed solution;

[0053] Step 4: Filter the mixed solution in step 3, add oxidant B, i.e., 30% hydrogen peroxide solution, to the filtrate, and then place it on a temperature-controlled heating furnace and heat it to 90°C, then add 350g of NH4Cl and perform oxidation reaction at a constant temperature of 90°C to 95°C for 3h to obtain (NH4)2IrCl6 precipitate; the potential of the solution system after the oxidation reaction is 750mV±30mV;

[0054] Step 5. Place the (NH4)2IrCl6 precipitate obtained in step 4 in aqua regia and heat to dissolve the broken ammonium to obtain H2IrCl6 solution, and concentrate the H2IrCl6 solution to an Ir mass content of 35%±0.3% in accordance with the YS / T 595-2022 "Chloroiridic Acid" standard, and the purity of the H2IrCl6 product meets the YS / T595-2022 "Chloroiridic Acid" standard.

[0055] After testing, the potassium ion concentration in the chloroiridic acid solution after potassium removal in this embodiment was reduced from 0.5% to about 0.012%, K + The removal rate reached 97.7%.

[0056] The reducing agent A in this embodiment can also be replaced by at least one of oxalic acid, formic acid, hydrazine hydrate and sodium sulfite other than hydrazine hydrate solution; the oxidizing agent B can also be replaced by at least one of hydrogen peroxide, sodium chlorate and chlorine gas other than hydrogen peroxide solution.

[0057] Example 4

[0058] like Figure 1 As shown, this embodiment includes the following steps:

[0059] Step 1, adding sponge platinum to the heated aqua regia in small amounts several times, and boiling to promote the dissolution of the sponge platinum until the solution is clear and free of filter residues, and concentrating to a Pt mass content of 37%, and then cooling and filtering to obtain a chloroplatinic acid solution as a potassium removal agent;

[0060] Step 2: Add reducing agent A, i.e., 50% hydrated hydrazine solution, to 1200 g of chloroiridic acid solution containing 0.5% potassium ion concentration for reduction, so that Ir(IV) is converted into Ir(III) to obtain a reduced solution; the potential of the solution system after the reduction reaction is 400 mV±30 mV;

[0061] Step 3: According to the potassium ion content of the reducing solution in step 2, 52 g of the chloroplatinic acid solution in step 1 is slowly added to the reducing solution, and the temperature is maintained at 20 ° C. and stirred for 3 hours to obtain a mixed solution;

[0062] Step 4: Filter the mixed solution in step 3, add oxidant B, i.e., 30% hydrogen peroxide solution, to the filtrate, and then place it on a temperature-controlled heating furnace and heat it to 90°C, then add 350g of NH4Cl and perform oxidation reaction at a constant temperature of 90°C to 95°C for 3h to obtain (NH4)2IrCl6 precipitate; the potential of the solution system after the oxidation reaction is 750mV±30mV;

[0063] Step 5. Place the (NH4)2IrCl6 precipitate obtained in step 4 in aqua regia and heat to dissolve the broken ammonium to obtain H2IrCl6 solution, and concentrate the H2IrCl6 solution to an Ir mass content of 35%±0.3% in accordance with the YS / T 595-2022 "Chloroiridic Acid" standard, and the purity of the H2IrCl6 product meets the YS / T595-2022 "Chloroiridic Acid" standard.

[0064] After testing, the potassium ion concentration in the chloroiridic acid solution after potassium removal in this embodiment was reduced from 0.5% to about 0.003%, K + The removal rate is up to 99.4%.

[0065] The reducing agent A in this embodiment can also be replaced by at least one of oxalic acid, formic acid, hydrazine hydrate and sodium sulfite other than hydrazine hydrate solution; the oxidizing agent B can also be replaced by at least one of hydrogen peroxide, sodium chlorate and chlorine gas other than hydrogen peroxide solution.

[0066] Example 5

[0067] like Figure 1 As shown, this embodiment includes the following steps:

[0068] Step 1, adding sponge platinum to the heated aqua regia in small amounts several times, and boiling to promote the dissolution of the sponge platinum until the solution is clear and free of filter residues, and concentrating to a Pt mass content of 37%, and then cooling and filtering to obtain a chloroplatinic acid solution as a potassium removal agent;

[0069] Step 2: Add reducing agent A, i.e., 50% hydrated hydrazine solution, to 1200 g of chloroiridic acid solution containing 0.5% potassium ion concentration for reduction, so that Ir(IV) is converted into Ir(III) to obtain a reduced solution; the potential of the solution system after the reduction reaction is 400 mV±30 mV;

[0070] Step 3: According to the potassium ion content of the reducing solution in step 2, 45 g of the chloroplatinic acid solution in step 1 is slowly added to the reducing solution, and the temperature is maintained at 35 ° C. and stirred for 3 hours to obtain a mixed solution;

[0071] Step 4: Filter the mixed solution in step 3, add oxidant B, i.e., 30% hydrogen peroxide solution, to the filtrate, and then place it on a temperature-controlled heating furnace and heat it to 90°C, then add 350g of NH4Cl and perform oxidation reaction at a constant temperature of 90°C to 95°C for 4h to obtain (NH4)2IrCl6 precipitate; the potential of the solution system after the oxidation reaction is 750mV±30mV;

[0072] Step 5. Place the (NH4)2IrCl6 precipitate obtained in step 4 in aqua regia and heat to dissolve the broken ammonium to obtain H2IrCl6 solution, and concentrate the H2IrCl6 solution to an Ir mass content of 35%±0.3% in accordance with the YS / T 595-2022 "Chloroiridic Acid" standard, and the purity of the H2IrCl6 product meets the YS / T595-2022 "Chloroiridic Acid" standard.

[0073] After testing, the potassium ion concentration in the chloroiridic acid solution after potassium removal in this embodiment was reduced from 0.5% to about 0.01%, K + The removal rate reached 98.0%.

[0074] The reducing agent A in this embodiment can also be replaced by at least one of oxalic acid, formic acid, hydrazine hydrate and sodium sulfite other than hydrazine hydrate solution; the oxidizing agent B can also be replaced by at least one of hydrogen peroxide, sodium chlorate and chlorine gas other than hydrogen peroxide solution.

[0075] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for removing potassium ions from a chloroiridic acid solution, characterized in that: The method comprises the following steps: Step 1, adding sponge platinum to the heated aqua regia in small amounts several times, and boiling to promote the dissolution of the sponge platinum until the solution is clear and free of filter residues, cooling and filtering to obtain a chloroplatinic acid solution as a potassium removal agent; Step 2: adding a reducing agent A to the chloroiridic acid solution for reduction, so that Ir(IV) is converted into Ir(III) to obtain a reduced solution; Step 3: according to the potassium ion content of the reducing solution in step 2, add the chloroplatinic acid solution in step 1 to the reducing solution, and keep the temperature at 20° C. to 40° C. and stir the reaction for 2 h to 4 h to obtain a mixed solution; Step 4: Filter the mixed solution in step 3, add oxidant B to the filtrate, heat it to 90°C to 95°C, add NH4Cl and carry out oxidation reaction at constant temperature for 2h to 4h to obtain (NH4)2IrCl6 precipitate; Step 5: Place the (NH4)2IrCl6 precipitate obtained in step 4 in aqua regia and heat to dissolve the broken ammonium to obtain H2IrCl6 solution, and concentrate the H2IrCl6 solution to an Ir mass content of 35%±0.3% according to the YS / T 595-2022 "Chloroiridic Acid" standard.

2. A method for removing potassium ions from a chloroiridic acid solution according to claim 1, characterized in that: The reducing agent A in step 2 is at least one of oxalic acid, formic acid, hydrazine hydrate and sodium sulfite.

3. A method for removing potassium ions from a chloroiridic acid solution according to claim 1, characterized in that: The potential of the solution system after the reduction reaction in step 2 is 400 mV±30 mV.

4. A method for removing potassium ions from a chloroiridic acid solution according to claim 1, characterized in that: The molar ratio of potassium ions in the reducing solution to platinum ions in the chloroplatinic acid solution in step 3 is n(K + ): n(Pt(VI))=2:0.5~1.

5.

5. A method for removing potassium ions from a chloroiridic acid solution according to claim 1, characterized in that: The oxidant B in step 4 is at least one of hydrogen peroxide, sodium chlorate and chlorine.

6. A method for removing potassium ions from a chloroiridic acid solution according to claim 1, characterized in that: The potential of the solution system after the oxidation reaction in step 4 is 750 mV±30 mV.

7. A method for removing potassium ions from a chloroiridic acid solution according to claim 1, characterized in that: The constant temperature condition in step 4 is 90°C ± 5°C.

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