Method for efficiently enriching iridium in acid tail liquid through coprecipitation

Abstract

The invention discloses a method for efficiently enriching iridium in acid tail liquid through coprecipitation, and belongs to the technical field of hydrometallurgy. In order to solve the problems of low recovery rate and high cost of an existing iridium recovery method, the method comprises the following steps: step 1, preparing materials: taking iridium-containing acidic tail liquid, detecting the content of iridium and iron, and then adding a proper amount of ferric chloride to enable the mass ratio of the iridium content to the iron content to be 1: 45; step 2, oxidation reaction: adding an oxidizing agent, uniformly stirring, and oxidizing residual iron ions in the solution into trivalent iron ions; step 3, alkali neutralization precipitation reaction: adding a small amount of precipitant into the tail liquid oxidized in the step 2 for multiple times until the pH value is 11-12; and 4, cooling and liquid-solid separation are conducted, specifically, the tail liquid neutralized in the step 3 is cooled to the room temperature, liquid-solid separation is conducted, precious metal iridium is enriched in solid residues, and the iridium precipitation rate is larger than 98%. The method has the advantages of being short in process, high in efficiency, beneficial to comprehensive recovery of precious metal iridium and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgy, and in particular relates to a method for efficiently enriching iridium in acidic tail liquid by coprecipitation. Background Art

[0002] Iridium belongs to the platinum group metals. It is expensive and scarce. Due to its superior performance, it is widely used in aerospace, electronics, new energy materials, medical equipment, petrochemicals, exhaust gas catalysis and other fields. It plays an irreplaceable role and is therefore called the "vitamin" of modern industry.

[0003] Iridium produces a large amount of industrial wastewater during the preparation of chemical products, catalyst synthesis, and coating application. It usually contains a small amount of precious metal ions, which is a typical secondary resource of precious metals and has considerable recycling value. Therefore, how to quickly, efficiently, and cost-effectively recycle precious metals in wastewater has become a key technical field of concern.

[0004] There is an urgent need for a method for recovering the precious metal iridium from high-salt, high-chlorine, multi-component impurity tail liquid. Summary of the invention

[0005] In view of the problems of low recovery rate and high cost in the current iridium recovery methods, the present invention provides a method for efficiently enriching the precious metal iridium in the acidic tail liquid by coprecipitation, which has the advantages of short process, high efficiency and is conducive to the comprehensive recovery of the precious metal iridium.

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

[0007] A method for efficiently enriching iridium in an acidic tail liquid by coprecipitation comprises the following steps:

[0008] Step 1, batching: taking the iridium-containing acid tail liquid, detecting the iridium and iron contents, and then adding an appropriate amount of ferric chloride so that the mass ratio of the iridium content to the iron content is 1:45;

[0009] Step 2, oxidation reaction: add an oxidant and stir evenly to oxidize the residual iron ions in the solution to trivalent iron ions;

[0010] Step 3, alkali neutralization precipitation reaction: add a precipitant in small amounts and multiple times to the tail liquid after oxidation in step 2 until the pH is 11-12;

[0011] Step 4, cooling and liquid-solid separation: the tail liquid after neutralization in step 3 is cooled to room temperature, and liquid-solid separation is performed, and the precious metal iridium is enriched in the solid slag.

[0012] In the process of forming colloidal precipitate Fe(OH)3, trivalent iron ions are used to enrich the low-content iridium in the tail liquid solution in the precipitate through surface adsorption and precipitate interaction.

[0013] Furthermore, the iridium content in the iridium-containing acidic tail liquid is 0.01% to 0.1%.

[0014] Furthermore, the oxidant is nitric acid.

[0015] Furthermore, the precipitant is solid sodium hydroxide.

[0016] Furthermore, in step 2, after adding the oxidant and stirring evenly, the mixture is kept warm at 60-70° C. for 1 hour.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. The method of the present invention is aimed at enriching low-content precious metal iridium in high-acidity, high-salt and complex solution systems. The selected process technology route has the advantages of short process, low cost, strong operability, wide applicability, and high iridium precipitation rate. 2. The present invention utilizes the principle of co-precipitation to achieve the enrichment of low-content precious metal iridium in acidic complex tail liquid, providing a new idea for the comprehensive utilization of precious metal iridium. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 The present invention is a process flow chart for enriching iridium from acidic complex tail liquid. DETAILED DESCRIPTION

[0021] In order to gain a deeper understanding of the present invention, we will provide a comprehensive and detailed description of the present invention. However, the present invention has multiple implementations and is not limited to the specific examples listed herein. The presentation of these examples is intended to deepen the comprehensive understanding of the disclosure of the present invention.

[0022] Example 1

[0023] The main metal components in the acidic tail liquid to be treated in this embodiment are as follows by weight: Ir 0.025%, Ca 0.66%, Fe 0.8%, Na 2.6%, Ni 0.05%. The implementation steps are as follows:

[0024] Step 1, ingredients: weigh 50 kg of pickling tail liquid, add an appropriate amount of ferric chloride so that the mass ratio of iridium to iron in the solution is 1:45;

[0025] Step 2, oxidation reaction: add 1000 mL of nitric acid to the solution prepared in step 1, stir evenly, heat to 70°C, and keep warm for 1 hour;

[0026] Step 3, coprecipitation reaction: select sodium hydroxide as the precipitant, and slowly add it into the solution in step 2 in small amounts and multiple times until the end point pH of the solution is 12;

[0027] Step 4, cooling and filtering: the solution obtained in step 3 is allowed to stand and cool to room temperature, and liquid-solid separation is performed. The content of precious metal iridium in the filtrate is detected to be 0.0001%, and the iridium precipitation rate is 99%.

[0028] Example 2

[0029] The difference from Example 1 is that in step 1, an appropriate amount of ferric chloride is added so that the mass ratio of iridium to iron in the solution is 1:44;

[0030] Example 3

[0031] The difference from Example 1 is that in step 1, an appropriate amount of ferric chloride is added so that the mass ratio of iridium to iron in the solution is 1:46;

[0032] Example 4

[0033] The difference from Example 1 is that in step 2, 1000 ml of H2O2 is added to the solution prepared in step 1;

[0034] Example 5

[0035] Different from Example 1, in step 2, the temperature is raised to 50°C;

[0036] Example 6

[0037] Different from Example 1, in step 2, the temperature is raised to 60°C;

[0038] Example 7

[0039] Different from Example 1, in step 2, the temperature is raised to 80°C;

[0040] Example 8

[0041] Different from Example 1, in step 3, the precipitant selected is sodium carbonate;

[0042] Comparative Example 1

[0043] Steps 2, 3 and 4 are the same as those in Example 1. In step 1, 50 kg of pickling tail liquid is weighed without adding ferric chloride;

[0044] The iridium content in the filtrate obtained in step 4 of implementation examples 1 to 8 and comparative example 1 was detected respectively, and the iridium precipitation rate was calculated. The results are shown in Table 1:

[0045] Table 1

[0046] Iridium concentration in filtrate (%) Iridium precipitation rate (%) Example 1 0.0004 99.6 Example 2 0.0009 99.1 Example 3 0.0005 99.5 Example 4 0.01 90 Example 5 0.009 91 Example 6 0.0007 99.3 Example 7 0.0005 99.5 Example 8 0.006 94 Comparative Example 1 0.03 70

[0047] Compared with Examples 1, 2, and 3, when the mass ratio of iridium to iron in the solution is 1:45, the iridium precipitation rate is the highest;

[0048] Comparative Examples 1 and 4, the use of nitric acid with strong oxidizing properties can keep the solution at a certain potential, so that the iridium and iron ion coprecipitation effect is the best;

[0049] Comparing implementations 1, 5, 6, and 7, the temperature of 60 to 70°C is the optimal parameter;

[0050] Compared with implementations 1 and 7, sodium hydroxide was used as the precipitant, and the iridium precipitation rate was the best;

[0051] By comparing Example 1 with Comparative Example 1, it can be seen that whether ferric chloride is added has a crucial effect on the iridium precipitation rate. The principle of co-precipitation of iron and iridium ions is used to efficiently enrich low-concentration precious metal ions in the acidic tail liquid.

[0052] The present invention mainly utilizes the surface adsorption of trivalent iron ions and the interaction of precipitates in the process of forming colloidal precipitates Fe(OH)3, so that low-content iridium in the tail liquid solution is enriched in the precipitate, and the content of precious metal iridium in the acidic tail liquid is changed from 0.1% to 0.01% to 0.0003% to 0.0001%, and the precipitation rate of low-content iridium in the tail liquid is greater than 98%.

[0053] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in the field. Although the illustrative specific embodiments of the present invention are described above to facilitate the understanding of the present invention by the technical personnel in the field, it should be clear that the present invention is not limited to the scope of the specific embodiments. For the ordinary technical personnel in the field, as long as various changes are within the spirit and scope of the present invention defined and determined by the attached claims, these changes are obvious, and all inventions and creations using the concept of the present invention are protected.

Claims

1. A method for efficiently enriching iridium in acidic tail liquid by coprecipitation, characterized in that: The following steps are involved: Step 1, batching: taking the iridium-containing acid tail liquid, detecting the iridium and iron contents, and then adding an appropriate amount of ferric chloride so that the mass ratio of the iridium content to the iron content is 1:45; Step 2, oxidation reaction: add an oxidant and stir evenly to oxidize the residual iron ions in the solution to trivalent iron ions; Step 3, alkali neutralization precipitation reaction: add a precipitant in small amounts and multiple times to the tail liquid after oxidation in step 2 until the pH is 11-12; Step 4, cooling and liquid-solid separation: the tail liquid after neutralization in step 3 is cooled to room temperature, and liquid-solid separation is performed, and the precious metal iridium is enriched in the solid slag.

2. A method for efficiently enriching iridium in an acidic tail liquid by coprecipitation according to claim 1, characterized in that: The iridium content in the iridium-containing acidic tail liquid is 0.01% to 0.1%.

3. A method for efficiently enriching iridium in an acidic tail liquid by coprecipitation according to claim 1, characterized in that: The oxidant is nitric acid.

4. A method for efficiently enriching iridium in an acidic tail liquid by coprecipitation according to claim 1, characterized in that: The precipitant is solid sodium hydroxide.

5. A method for efficiently enriching iridium in an acidic tail liquid by coprecipitation according to claim 1, characterized in that: In step 2, after adding the oxidant and stirring evenly, the mixture is kept warm at 60-70° C. for 1 hour.

Images