Method for rapidly preparing chloroiridic acid from acidic iridium-containing waste liquid

Abstract

The invention relates to the technical field of precious metal recovery, in particular to a method for rapidly preparing chloroiridic acid from acidic iridium-containing waste liquid, which comprises the following steps: preparing chloroiridic acid by adopting the processes of heating hydrolysis, oxidation precipitation, reduction dissolution, sulfuration impurity removal, oxidation precipitation and aqua regia dissolution. The process of recovering iridium from the iridium-containing solution and preparing chloroiridic acid is simplified, the recovery process is short, the operability is high, the waste liquid treatment amount is large, the auxiliary material consumption is low, the loss of iridium is reduced, and the recovery efficiency is remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of precious metal recovery, and in particular to a method for quickly preparing chloroiridic acid from acidic iridium-containing waste liquid. Background Art

[0002] In recent years, with the rapid development of electronics, electrochemistry and other fields, iridium has been widely used and plays an irreplaceable role in certain industries. Especially in the field of titanium anodes, chloroiridic acid and tantalum pentachloride are the main raw materials for titanium-based iridium-tantalum coated electrodes. Due to the advantages of high current density carrying capacity, low oxygen evolution potential, excellent electrolysis durability and good dimensional stability of iridium-tantalum coated anodes, it occupies an important position. In the process of titanium anode preparation, a large amount of acidic iridium-containing waste liquid is generated. The price of iridium is high. The recovery of iridium in acidic iridium-containing waste liquid is crucial to reducing the cost of iridium-tantalum titanium anodes.

[0003] For the recovery of iridium in solution, a common method is to convert iridium into oxide by evaporating the solvent and then roasting it so that it exists in the form of oxide, and then use medium-temperature chlorination method, alkali melting method, etc. to convert iridium into an easily soluble form, and convert iridium into solution by hydrochloric acid leaching. The process is cumbersome and lengthy, with large iridium loss, the need to add a large amount of auxiliary materials, and repeated melting, resulting in a low recovery rate.

[0004] Therefore, developing a method for efficiently recovering iridium from acidic iridium-containing waste liquid and converting it into chloroiridic acid is of great significance for reducing the production cost of iridium-tantalum anodes. Summary of the invention

[0005] In order to solve the above problems, the purpose of the present invention is to provide a method for quickly preparing chloroiridic acid from acidic iridium-containing waste liquid, wherein chloroiridic acid is prepared by hydrolysis and impurity removal, oxidation precipitation of iridium and dissolution in aqua regia, and the method has the advantages of short recovery process, strong operability, low consumption of auxiliary materials, reduced loss of iridium, and significantly improved recovery efficiency and recovery rate.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for rapidly preparing chloroiridic acid from acidic iridium-containing waste liquid comprises the following steps:

[0008] Step 1, heating and hydrolysis: heating the acidic iridium-containing waste liquid to remove impurities that are easily hydrolyzed;

[0009] Step 2, oxidation precipitation: the waste liquid treated in step 1 is subjected to solid-liquid separation, an oxidant is added to the separated solution for heating, and then ammonium chloride is added for precipitation, wherein the volume ratio of the oxidant to the solution is 1:20 to 60;

[0010] Step 3, reduction dissolution: the reaction product obtained in step 2 is subjected to solid-liquid separation, the separated solid is slurried with water, a reducing agent is added, and the mixture is heated, wherein the volume ratio of the reducing agent to the slurried solution is 1:50 to 200;

[0011] Step 4, sulfurization and impurity removal: the reaction product obtained in step 3 is subjected to solid-liquid separation, and the separated solution is added with a sulfurizing agent to carry out sulfurization and impurity removal at room temperature, wherein the volume ratio of the sulfurizing agent to the solution is 1:20 to 100;

[0012] Step 5, oxidation precipitation: the reaction product obtained in step 4 is subjected to solid-liquid separation, an oxidant is added to the separated solution and heated, and then ammonium chloride is added for precipitation, wherein the volume ratio of the oxidant to the solution is 1:10 to 50;

[0013] Step 6, dissolving in aqua regia: subjecting the reaction product obtained in step 5 to solid-liquid separation, dissolving the separated solid in aqua regia and heating and concentrating to obtain chloroiridic acid.

[0014] Preferably, in step 1, the heating conditions are: heating temperature is 80-100° C., and heating time is 0.5-2 h.

[0015] Preferably, in step 2, the oxidant is any one of nitric acid, sodium hypochlorite, and hydrogen peroxide; the amount of ammonium chloride added is 20 g / L to 80 g / L, preferably 40 g / L to 60 g / L; the heating conditions are: the heating temperature is 80 to 100° C., and the heating time is 2 to 8 hours, preferably 2 to 4 hours.

[0016] Preferably, in step 3, the reducing agent is any one of ammonium sulfide, sodium sulfide, and hydrazine hydrate; the reduction reaction temperature is 70-100° C., and the reaction time is 0.5-2 h.

[0017] Preferably, in step 4, the vulcanizing agent is ammonium sulfide or sodium sulfide; the vulcanization temperature is 25 to 100° C., and the vulcanization time is 0.5 to 24 hours.

[0018] Preferably, in step 5, the oxidant is any one of nitric acid, hydrogen peroxide, and sodium hypochlorite; the amount of ammonium chloride added is 40 g / L to 60 g / L; the heating temperature is 80 to 100° C., and the heating time is 2 to 8 hours, preferably 4 to 6 hours.

[0019] Preferably, in step 6, the liquid-to-solid ratio of the aqua regia to the solid is 3 to 8:1, and the unit of the liquid-to-solid ratio is ml / g.

[0020] Preferably, the solid-liquid separation method is centrifugal separation or vacuum filtration, preferably centrifugal separation, and the centrifuge speed is 5000-11000 rpm, preferably 8000-10000 rpm.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. The present invention adopts a heating hydrolysis method to quickly remove impurities such as tantalum in the solution, and can achieve preliminary purification of the iridium-containing solution, which has the effects of convenient operation and high impurity removal efficiency.

[0023] 2. The present invention adopts oxidation precipitation, which can accelerate the rapid enrichment of iridium in the iridium-containing solution through oxidation with an oxidant, and quickly achieve the purpose of quickly separating iridium from other impurities in the solution. The iridium is converted from the ionic state in the solution to a solid state and separated, and has the effects of strong operability, large processing capacity, short time consumption and low iridium loss.

[0024] 3. The present invention adopts reduction dissolution, which can realize the rapid conversion of iridium in a solid state into a free state in a solution, and has the effects of low auxiliary material consumption and fast reaction.

[0025] 4. The present invention adopts sulfidation to remove impurities, which can effectively remove precious metal and base metal impurities in the iridium-containing solution, is easy to operate, saves manpower and has low auxiliary material cost.

[0026] In summary, the present invention adopts the process of heating hydrolysis, oxidation precipitation, reduction dissolution, sulfidation impurity removal, oxidation precipitation and aqua regia dissolution to prepare chloroiridic acid, simplifies the process of recovering iridium from an iridium-containing solution and preparing chloroiridic acid, has a short recovery process, strong operability, a large amount of waste liquid treatment, and a small amount of auxiliary material consumption, reduces the loss of iridium, and significantly improves the recovery efficiency. DETAILED DESCRIPTION

[0027] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention. The reagents used therein should be understood to be conventional commercial reagents or prepared according to the prior art unless otherwise specified; the operating methods used therein should be understood to be conventional operations in the art unless otherwise specified.

[0028] The method for rapidly preparing chloroiridic acid from acidic iridium-containing waste liquid provided by the present invention comprises the following steps:

[0029] Step 1, heating and hydrolysis: heating the acidic iridium-containing waste liquid at a temperature of 80-100° C. for 0.5-2 h, preferably 1-2 h, to remove impurities that are easily hydrolyzed; the acidic iridium-containing waste liquid is an extremely acidic iridium-containing solution containing a small amount of organic solvent, which contains some impurity elements such as tantalum.

[0030] Step 2, oxidation precipitation: the waste liquid treated in step 1 is separated into solid and liquid, and the solid is treated as hazardous waste. An oxidant is added to the separated solution to break a small amount of organic matter and heat and oxidize the iridium, and then ammonium chloride is added for precipitation. The volume ratio of the oxidant to the solution is 1:20-60; the oxidant is any one of nitric acid, sodium hypochlorite, and hydrogen peroxide; nitric acid is preferably used in the embodiment of the present invention. The amount of ammonium chloride added is 20g / L-80g / L, preferably 40g / L-60g / L; the heating conditions are: the heating temperature is 80-100°C, and the heating time is 2-8h, preferably 2-4h.

[0031] Step 3, reduction dissolution: the reaction product obtained in step 2 is subjected to solid-liquid separation, the separated solid is slurried with water, and then a reducing agent is added, and the reaction is carried out at a reaction temperature of 70 to 100° C. and a reaction time of 0.5 to 2 h. The volume ratio of the reducing agent to the slurried solution is 1:50 to 200; the reducing agent is any one of ammonium sulfide, sodium sulfide, and hydrazine hydrate; the reducing agent in the embodiment of the present invention is preferably hydrazine hydrate.

[0032] Step 4, sulfurization and impurity removal: the reaction product obtained in step 3 is subjected to solid-liquid separation, and a sulfurizing agent is added to the separated solution to carry out sulfurization and impurity removal at a temperature of 25 to 100° C. and a sulfurization time of 0.5 to 24 hours, wherein the volume ratio of the sulfurizing agent to the solution is 1:20 to 100; the sulfurizing agent is ammonium sulfide or sodium sulfide; and the sulfurizing agent in the embodiment of the present invention is preferably ammonium sulfide.

[0033] Step 5, oxidation precipitation: the reaction product obtained in step 4 is subjected to solid-liquid separation, an oxidant is added to the separated solution and heated, and then ammonium chloride is added for precipitation, the volume ratio of the oxidant to the solution is 1:10-50; the oxidant is any one of nitric acid, hydrogen peroxide, and sodium hypochlorite; the oxidant in the embodiment of the present invention is preferably nitric acid or hydrogen peroxide. The amount of ammonium chloride added is 40g / L-60g / L; the heating temperature is 80-100°C, and the heating time is 1-8h, preferably 1-4h.

[0034] Step 6, dissolving in aqua regia: performing solid-liquid separation on the reaction product obtained in step 5, dissolving the separated solid in aqua regia for reaction for 3-4 hours and heating and concentrating to drive out nitric acid and acid to obtain chloroiridic acid; the liquid-solid ratio of aqua regia to solid is 3-8:1, and the unit of liquid-solid ratio is ml / g.

[0035] In the present invention, the solid-liquid separation method is centrifugal separation or vacuum filtration, preferably centrifugal separation, and the centrifuge speed is 5000-11000 rpm, preferably 8000-10000 rpm.

[0036] Example 1

[0037] A method for rapidly preparing chloroiridic acid from acidic iridium-containing waste liquid comprises the following steps:

[0038] Step 1, heating 200 ml of acidic iridium-containing waste liquid at 80° C. for 2 h;

[0039] Step 2, using a centrifugal separation method, using a centrifuge to separate the reaction product in step 1 into solid and liquid at a speed of 10,000 rpm, the solid is treated as hazardous waste, 10 ml of nitric acid is added to the liquid to react at 80° C. for 4 hours, and then 8 g of ammonium chloride is added for precipitation;

[0040] Step 3, using a centrifugal separation method, using a centrifuge to separate the reaction product in step 2 into solid and liquid at a speed of 10,000 rpm, adding 70 ml of water to 8 g of the obtained solid to make a slurry, and then adding 0.4 ml of hydrazine hydrate to react at 100° C. for 0.5 h for reduction;

[0041] Step 4, using a centrifugal separation method, using a centrifuge to separate the reaction product in step 3 into solid and liquid at a speed of 10,000 rpm, adding 1 ml of 4% ammonium sulfide by mass to the obtained liquid and reacting at room temperature for 24 hours for sulfidation and impurity removal;

[0042] Step 5, using centrifugal separation method, using a centrifuge, at a speed of 10000 rpm, the reaction product in step 4 is separated into solid and liquid, 4 ml of nitric acid is added to the obtained liquid for oxidation, reacted at 80° C. for 4 hours, and then 8 g of ammonium chloride is added for precipitation.

[0043] Step 6, using centrifugal separation method, using a centrifuge, at a speed of 10000 rpm, the reaction product in step 5 is separated into solid and liquid, and 24 ml of aqua regia is added to the obtained solid to react for 3 hours and heated and concentrated to drive out nitric acid and acid to obtain chloroiridic acid.

[0044] Example 2

[0045] Step 1, heating 300 ml of acidic iridium-containing waste liquid at 90° C. for 1 h;

[0046] Step 2, using a centrifugal separation method, using a centrifuge to separate the reaction product in step 1 into solid and liquid at a speed of 9000 rpm, the solid is treated as hazardous waste, 15 ml of nitric acid is added to the liquid to react at 90° C. for 3 hours, and then 12 g of ammonium chloride is added for precipitation;

[0047] Step 3, using a centrifugal separation method, using a centrifuge to separate the reaction product in step 2 into solid and liquid at a speed of 9000 rpm, adding 100 ml of water to slurry the obtained solid, and then adding 2 ml of hydrazine hydrate to react at 80° C. for 1 hour for reduction;

[0048] Step 4, using a centrifugal separation method, using a centrifuge to separate the reaction product in step 3 into solid and liquid at a speed of 9000 rpm, adding 3 ml of 4% ammonium sulfide by mass to the obtained liquid, reacting at 80° C. for 2 hours to perform sulfide removal;

[0049] Step 5, using centrifugal separation method, using a centrifuge, the reaction product in step 4 is separated into solid and liquid at a speed of 9000 rpm, 8 ml of nitric acid is added to the obtained liquid for oxidation, reacted at 90° C. for 2 hours, and then 12 g of ammonium chloride is added for precipitation.

[0050] Step 6, using centrifugal separation method, using a centrifuge, at a speed of 9000 rpm, the reaction product in step 5 is separated into solid and liquid, and 35 ml of aqua regia is added to the obtained solid to react for 3 hours and heated and concentrated to drive out nitric acid and acid to obtain chloroiridic acid.

[0051] Example 3

[0052] Step 1, heating 400 ml of acidic iridium-containing waste liquid at 100° C. for 1 h;

[0053] Step 2, using a centrifugal separation method, using a centrifuge to separate the reaction product in step 1 into solid and liquid at a speed of 9500 rpm, the solid is treated as hazardous waste, 25 ml of nitric acid is added to the liquid to react at 100° C. for 2 hours, and then 20 g of ammonium chloride is added for precipitation;

[0054] Step 3, using a centrifugal separation method, using a centrifuge to separate the reaction product in step 2 into solid and liquid at a speed of 9500 rpm, adding 200 ml of water to 16 g of the obtained solid to make a slurry, and then adding 4 ml of hydrazine hydrate to react at 70° C. for 2 h for reduction;

[0055] Step 4, using a centrifugal separation method, using a centrifuge to separate the reaction product in step 3 into solid and liquid at a speed of 9500 rpm, adding 6 ml of 4% ammonium sulfide by mass to the obtained liquid, reacting at 100° C. for 0.5 h and then reacting at room temperature for 12 h to perform sulfide removal;

[0056] Step 5, using a centrifugal separation method, using a centrifuge to separate the reaction product in step 4 into solid and liquid at a speed of 9500 rpm, adding 20 ml of hydrogen peroxide to the obtained liquid for oxidation, reacting at 100° C. for 1 hour, and then adding 16 g of ammonium chloride for precipitation;

[0057] Step 6, using centrifugal separation method, using a centrifuge, at a speed of 9500 rpm, the reaction product in step 5 is separated into solid and liquid, and 60 ml of aqua regia is added to the obtained solid to react for 4 hours and heated and concentrated to drive out nitric acid and acid to obtain chloroiridic acid.

[0058] Example 4

[0059] Step 1, heating 1000 ml of acidic iridium-containing waste liquid at 100° C. for 1 h;

[0060] Step 2, using a centrifugal separation method, using a centrifuge to separate the reaction product in step 1 into solid and liquid at a speed of 8000 rpm, the solid is treated as hazardous waste, 50 ml of nitric acid is added to the liquid to react at 100° C. for 2 hours, and then 50 g of ammonium chloride is added for precipitation;

[0061] Step 3, using a centrifugal separation method, using a centrifuge to separate the reaction product in step 2 into solid and liquid at a speed of 8000 rpm, adding 200 ml of water to 40 g of the obtained solid to make a slurry, and then adding 4 ml of hydrazine hydrate to react at 100° C. for 0.5 h for reduction;

[0062] Step 4, using a centrifugal separation method, using a centrifuge to separate the reaction product in step 3 into solid and liquid at a speed of 8000 rpm, adding 6 ml of 4% ammonium sulfide by mass to the obtained liquid and reacting at 60° C. for 3 hours to perform sulfide removal;

[0063] Step 5, using a centrifugal separation method, using a centrifuge to separate the reaction product in step 4 into solid and liquid at a speed of 8000 rpm, adding 20 ml of nitric acid to the obtained liquid for oxidation, reacting at 90° C. for 2 h, and then adding 50 g of ammonium chloride for precipitation;

[0064] Step 6, using centrifugal separation method, using a centrifuge, at a speed of 8000 rpm, the reaction product in step 5 is separated into solid and liquid, and 200 ml of aqua regia is added to the obtained solid to react for 4 hours and heated and concentrated to drive out nitric acid and acid to obtain chloroiridic acid.

[0065] Comparative Example

[0066] Take 1000ml of acidic iridium-containing waste liquid and place it on a heating furnace, heat and evaporate until the solvent is completely volatilized, then place it in a muffle furnace for roasting, mix the roasted powder with NaOH and Na2O2 in a certain proportion, and then place it in a muffle furnace for high-temperature firing for 2h. After the reaction, add 10% hydrochloric acid to dissolve the solid, filter it, and perform secondary firing on the insoluble residue with NaOH and Na2O2. Add 10ml nitric acid to the filtrate for oxidation, add ammonium chloride after oxidation for chemical precipitation, add aqua regia to dissolve the obtained solid, filter to remove the insoluble residue, exchange the filtrate with a strong acid cationic resin to remove impurities in the iridium solution, exchange it twice, and then regenerate the resin with 6mol / L hydrochloric acid. The regenerated liquid has a large volume, and aqua regia is added to it for oxidation and concentrated precipitation to obtain ammonium chloroiridate solid. The solid is added with aqua regia to dissolve and drive out nitric acid and acid to obtain a chloroiridic acid solution.

[0067] In summary, according to the comparison of the operation flow of Examples 1 to 4 with the comparative example, it can be seen that the embodiment of the present invention controls the amount of oxidant added and the oxidation time in the oxidation precipitation process to quickly achieve the enrichment of iridium in the waste liquid, reduce the long time consumption caused by the solvent evaporation process and the poor solubility of the solid obtained after evaporation, and the subsequent reduction dissolution is fast, short time consumption and less auxiliary material consumption compared to the comparative example of aqua regia dissolution, and the operation efficiency is high; the embodiment of the present invention adopts sulfidation impurity removal to simultaneously remove precious metal and base metal impurities in the solution, and the ion exchange impurity removal process in the comparative example has a large processing capacity and high efficiency. The present invention simplifies the process of recovering iridium from an iridium-containing solution and preparing chloroiridic acid, with a short recovery process, strong operability, large waste liquid processing capacity, and low auxiliary material consumption, which reduces the loss of iridium and significantly improves the recovery efficiency.

Claims

1. A method for rapidly preparing chloroiridic acid from acidic iridium-containing waste liquid, characterized in that: The following steps are involved: Step 1, heating and hydrolysis: heating the acidic iridium-containing waste liquid to remove impurities that are easily hydrolyzed; Step 2, oxidation precipitation: the waste liquid treated in step 1 is subjected to solid-liquid separation, an oxidant is added to the separated solution for heating, and then ammonium chloride is added for precipitation, wherein the volume ratio of the oxidant to the solution is 1:20 to 60; Step 3, reduction dissolution: the reaction product obtained in step 2 is subjected to solid-liquid separation, the separated solid is slurried with water, a reducing agent is added, and the mixture is heated, wherein the volume ratio of the reducing agent to the slurried solution is 1:50 to 200; Step 4, sulfurization and impurity removal: the reaction product obtained in step 3 is subjected to solid-liquid separation, and the separated solution is added with a sulfurizing agent to carry out sulfurization and impurity removal at room temperature, wherein the volume ratio of the sulfurizing agent to the solution is 1:20 to 100; Step 5, oxidation precipitation: the reaction product obtained in step 4 is subjected to solid-liquid separation, an oxidant is added to the separated solution and heated, and then ammonium chloride is added for precipitation, wherein the volume ratio of the oxidant to the solution is 1:10 to 50; Step 6, dissolving in aqua regia: subjecting the reaction product obtained in step 5 to solid-liquid separation, dissolving the separated solid in aqua regia and heating and concentrating to obtain chloroiridic acid.

2. The method for rapidly preparing chloroiridic acid from acidic iridium-containing waste liquid according to claim 1, characterized in that: In step 1, the heating conditions are: heating temperature is 80-100° C., and heating time is 0.5-2 h.

3. The method for rapidly preparing chloroiridic acid from acidic iridium-containing waste liquid according to claim 1, characterized in that: In step 2, the oxidant is any one of nitric acid, sodium hypochlorite, and hydrogen peroxide; The amount of ammonium chloride added is 20 g / L to 80 g / L, preferably 40 g / L to 60 g / L; The heating conditions are as follows: the heating temperature is 80-100° C., and the heating time is 2-8 hours, preferably 2-4 hours.

4. The method for rapidly preparing chloroiridic acid from acidic iridium-containing waste liquid according to claim 1, characterized in that: In step 3, the reducing agent is any one of ammonium sulfide, sodium sulfide, and hydrazine hydrate; The reduction reaction temperature is 70-100° C., and the reaction time is 0.5-2 h.

5. The method for rapidly preparing chloroiridic acid from acidic iridium-containing waste liquid according to claim 1, characterized in that: In step 4, the sulfiding agent is ammonium sulfide or sodium sulfide; The vulcanization temperature is 25-100° C., and the vulcanization time is 0.5-24 hours.

6. The method for rapidly preparing chloroiridic acid from acidic iridium-containing waste liquid according to claim 1, characterized in that: In step 5, the oxidant is any one of nitric acid, hydrogen peroxide, and sodium hypochlorite; The amount of ammonium chloride added is 40g / L to 60g / L; The heating temperature is 80-100° C., and the heating time is 2-8 hours, preferably 4-6 hours.

7. The method for rapidly preparing chloroiridic acid from acidic iridium-containing waste liquid according to claim 1, characterized in that: In step 6, the liquid-to-solid ratio of the aqua regia to the solid is 3 to 8:1, and the unit of the liquid-to-solid ratio is ml / g.

8. The method for rapidly preparing chloroiridic acid from acidic iridium-containing waste liquid according to claim 1, characterized in that: The solid-liquid separation method is centrifugal separation or vacuum filtration, preferably centrifugal separation, and the centrifuge speed is 5000-11000 rpm, preferably 8000-10000 rpm.