Method for recovering indium from indium-containing acidic waste liquid

Abstract

The invention belongs to the technical field of metal recovery, and discloses a method for recovering indium from indium-containing acidic waste liquid, which comprises the following steps: adding an alkaline solution into the indium-containing acidic waste liquid until the pH value is 8-14 to obtain an intermediate liquid I, adding a flocculating agent into the intermediate liquid I, and carrying out filter pressing to obtain filter residues; the flocculating agent is selected from at least one of polyacrylamide, polyaluminum chloride, polyferric sulfate, polyferrous sulfate and polyaluminum sulfate, the reducing agent is selected from at least one of graphite powder, coke and anthracite, the flocculating agent is selected from at least one of sodium hydroxide, sodium hydroxide and sodium hydroxide, and the reducing agent is selected from at least one of sodium hydroxide, sodium hydroxide and sodium hydroxide. According to the method, indium in the indium-containing acidic waste liquid is preliminarily settled by adjusting the pH value, and then part of residual metal indium with positive charges is further settled and gathered by using the flocculating agent, so that the recovery rate of indium is increased.

Description

Technical Field

[0001] The present application relates to the technical field of metal recovery, and in particular to a method for recovering indium from indium-containing acidic waste liquid. Background Art

[0002] Indium is a rare metal element. Due to its unique physical and chemical properties, it occupies an important position in modern science and technology and industrial applications. The main application areas include liquid crystal displays (LCDs), touch screens, semiconductors, photovoltaic industries, and military and aerospace fields. However, due to the extremely low content of indium in the earth's crust, the distribution of indium ore resources is relatively concentrated in a few countries, which makes indium an extremely scarce and strategically important resource. The global annual output of indium is extremely limited, but its market demand is growing, especially in the application of high-tech industries, which makes the contradiction between supply and demand increasingly aggravated. Traditional indium mining is not only costly, but also extremely destructive to the environment. In view of this, improving the recycling rate of indium resources has become an urgent need to solve this problem.

[0003] The mining and purification process of indium is usually accompanied by a large amount of waste and pollutant emissions, causing serious harm to the surrounding environment and ecosystem. In contrast, the recycling process of indium can significantly reduce the environmental burden and avoid further pollution of the environment by discarded electronic products and solar panels. Due to the high market value of indium, recycling can greatly reduce the production costs of enterprises and reduce dependence on primary indium mines, thereby improving economic benefits. Especially in the context of the continuous advancement of modern technology, indium recycling technology is becoming more and more mature, and the recovery rate and purity are increasing year by year, further enhancing its economic benefits. The wide application of indium in high-tech products, such as LCD displays and touch screens, makes this material an irreplaceable and important component of high-tech industries. With the development of smart electronic products and clean energy technologies, the demand for indium is also increasing. Through effective recycling, the continuous demand for indium in high-tech industries can be guaranteed and the sustainable development of the industry can be promoted.

[0004] Indium not only plays an important role in the civilian high-tech industry, but also has key applications in national strategic fields such as military and aerospace. By improving the recycling rate of indium, we can effectively reduce dependence on imported resources and enhance the independent capabilities of domestic industries. In the process of indium recycling, the research and development and application of various new technologies continue to emerge, improving the efficiency of resource utilization. By continuously exploring and optimizing recycling technology, we can promote technological progress in the entire industrial chain, drive the development of related equipment manufacturing and environmental protection treatment industries, and form a relatively complete and technologically advanced industrial system.

[0005] Standardizing and promoting the recycling of indium will help enhance the public's environmental awareness, promote the rational recycling and treatment of waste electronic products, reduce resource waste, optimize resource utilization, and maximize social benefits. In summary, given the scarcity of indium resources, high demand, and the impact of its mining and purification processes on the environment, recycling indium resources can not only effectively alleviate the contradiction between supply and demand, reduce damage to the environment, and improve the economic benefits of enterprises, but also meet the needs of the sustainable development of high-tech industries, promote technological progress and industrial upgrading, and achieve significant social benefits. Therefore, improving the recycling rate of indium has important practical significance and long-term strategic value.

[0006] Chinese patent application 201610039562.6 discloses a method for recovering copper indium gallium selenide materials, which mainly includes the steps of sulfuric acid roasting, acid dissolution, extraction of electrolytic copper metal, production of gallium hydroxide precipitation, replacement of indium, etc. The method for recovering copper indium gallium selenide materials in this scheme adopts sulfuric acid roasting to remove selenium. The remaining slag after roasting is an oxide slag that can be directly acid-dissolved, thereby reducing acid gas pollution; at the same time, copper extractant is used to extract copper, which has good separation effect and low cost, and the extracted copper is directly electrolyzed to obtain high-purity metallic copper; on the other hand, this scheme adopts alkaline gallium separation, and only needs to adjust the pH value of the solution to achieve indium and gallium separation, which solves the co-extraction problem when extracting and separating indium and gallium, has good separation effect, and the obtained indium and gallium products have high purity; but this scheme does not use flocculants to flocculate indium hydroxide;

[0007] Chinese patent application 201310388675.3 discloses a method for treating heavy metal wastewater, comprising: (a) introducing heavy metal wastewater into a wastewater reaction tank;

[0008] (b) adding an appropriate amount of ion precipitation agent to the heavy metal wastewater for precipitation;

[0009] (c) adding an appropriate amount of flocculant to the settled heavy metal wastewater for efficient flocculation;

[0010] (d) adding an appropriate amount of coagulant to the heavy metal wastewater after the flocculant is added;

[0011] (e) allowing the heavy metal wastewater to settle for a certain period of time after the addition of the coagulant aid;

[0012] (f) Separate the precipitated flocs from the heavy metal wastewater.

[0013] The process flow of this scheme is simple, the raw materials of the reagents are easy to obtain, the cost is low, and no new "three wastes" are generated during the treatment process. The treatment effect is significant. After flocculation-ion sedimentation treatment, the concentration of residual heavy metal ions in the water is far lower than the national emission standards, and the average removal rate is as high as over 95%; however, there may be differences in the flocculation effects of different flocculants on different metal ions.

[0014] The problem that this scheme needs to solve is: how to propose a method for recovering indium from indium-containing acidic waste liquid with a high recovery rate. Summary of the invention

[0015] The purpose of the present invention is to provide a method for recovering indium from indium-containing acidic waste liquid. The method firstly adjusts the pH value to make the indium in the indium-containing acidic waste liquid undergo preliminary sedimentation, and then uses a flocculant to cause part of the residual positively charged indium to precipitate and aggregate in one step, thereby improving the recovery rate of indium.

[0016] To achieve the above object, the present application discloses a method for recovering indium from indium-containing acidic waste liquid, comprising the following steps:

[0017] Step 1: adding an alkaline solution to the indium-containing acidic waste liquid until the pH is 8 to 14 to obtain an intermediate solution 1;

[0018] Step 2: adding a flocculant to the intermediate solution 1 obtained in step 1, followed by filter pressing to obtain a filter residue;

[0019] Step 3: calcining the filter residue obtained in step 2 once to obtain crude indium oxide, then mixing the crude indium oxide with a reducing agent, and calcining it twice to obtain metallic indium;

[0020] The flocculant is selected from at least one of polyacrylamide, polyaluminium chloride, polyferric sulfate, polyferrous sulfate and polyaluminium sulfate;

[0021] The reducing agent is selected from at least one of graphite powder, coke and anthracite.

[0022] Preferably, the flocculant is a mixture of polyacrylamide and polyaluminium chloride, and the mass ratio of polyacrylamide to polyaluminium chloride is 1 to 3:1.

[0023] Preferably, in step 2, the mass ratio of flocculant to intermediate liquid 1 is 1 to 5:100.

[0024] Preferably, the reducing agent is graphite powder, and in step 3, the mass ratio of crude indium oxide to the reducing agent is 1 to 5:1.

[0025] Preferably, the mass of indium ions in the indium-containing acidic waste liquid is at least 90% of the total mass of metal ions.

[0026] Preferably, in the primary calcination process, the calcination temperature is 300-700° C. and the calcination time is 2-6 hours.

[0027] Preferably, during the secondary calcination process, the calcination temperature is 600-1000° C. and the time is 4-6 hours.

[0028] Preferably, step 3 specifically comprises: calcining the filter residue obtained in step 2 once to obtain crude indium oxide, then mixing the crude indium oxide with a reducing agent and a slag-forming agent, and calcining twice to obtain metallic indium;

[0029] The slag-forming agent is selected from at least one of quartz, borax and sodium carbonate;

[0030] The mass ratio of crude indium oxide, reducing agent and slag-forming agent is 1-5:1:4.

[0031] Preferably, the indium recovery rate of the method for recovering indium from indium-containing acidic waste liquid is greater than or equal to 90%.

[0032] The beneficial effects of the present invention are:

[0033] The invention provides a method for recovering indium from indium-containing acidic waste liquid. The method firstly adjusts the pH value to make the indium in the indium-containing acidic waste liquid undergo preliminary sedimentation, then uses a flocculant to further precipitate and aggregate some of the residual positively charged indium, thereby improving the recovery rate of indium, and finally reduces the indium-containing oxide by a reducing agent to recover indium metal. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is the EDS energy spectrum of the O element in the metallic indium obtained in Example 8;

[0035] Figure 2 This is the EDS energy spectrum of the In element in the metallic indium obtained in Example 8;

[0036] Figure 3 This is the EDS energy spectrum of the O element in the metallic indium obtained in Example 1;

[0037] Figure 4 This is the EDS energy spectrum of the In element in the metallic indium prepared in Example 1. DETAILED DESCRIPTION

[0038] In the description of the present invention, it should be noted that, if the specific conditions are not specified in the examples, the experiments were carried out according to conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used, if the manufacturer is not specified, are all conventional products that can be purchased commercially.

[0039] Example 1

[0040] Step 1: adding an alkaline solution to 1 L of indium-containing acidic waste liquid until the pH is 8 to obtain an intermediate solution 1;

[0041] It should be noted that the indium-containing acidic waste liquid used in this embodiment is taken from the waste liquid generated in the actual production process. After testing (in the indium-containing acidic waste liquid, the mass of indium ions is 3693ppm of the total volume of the indium-containing acidic waste liquid, the mass of tin ions is 103ppm of the total volume of the indium-containing acidic waste liquid, and the mass of other metal ions is 22ppm of the total volume of the indium-containing acidic waste liquid;

[0042] The above-mentioned other metal ions are other metal ions contained in the indium-containing acidic waste liquid except indium ions and tin ions. According to detection, the other metal ions in this embodiment are specifically copper ions, iron ions, zinc ions, aluminum ions, and molybdenum ions.

[0043] Step 2: adding a flocculant to the intermediate solution 1 obtained in step 1, followed by filter pressing to obtain a filter residue;

[0044] The indium ion content in the intermediate solution 1 remaining after the filter press was tested, and the results showed that the indium ion content in the intermediate solution 1 remaining after the filter press was 352 ppm.

[0045] Step 3: calcining the filter residue obtained in step 2 once, during which the calcination temperature is 300° C. and the time is 6 hours to obtain crude indium oxide;

[0046] Subsequently, the crude indium oxide is mixed with a reducing agent and subjected to secondary calcination. During the secondary calcination, the calcination temperature is 600° C. and the time is 6 hours to obtain metallic indium.

[0047] The flocculant is polyacrylamide, and the mass ratio of polyacrylamide to the intermediate liquid is 1:100;

[0048] The reducing agent is graphite powder, and the mass ratio of the crude indium oxide to the reducing agent is 3:1.

[0049] Example 2

[0050] Step 1: adding an alkaline solution to an indium-containing acidic waste liquid (taken from the same source as in Example 1) until the pH is 14 to obtain an intermediate solution 1;

[0051] Step 2: adding a flocculant to the intermediate solution 1 obtained in step 1, followed by filter pressing to obtain a filter residue;

[0052] The indium ion content in the intermediate solution 1 remaining after the filter press was tested, and the results showed that the indium ion content in the intermediate solution 1 remaining after the filter press was 361 ppm.

[0053] Step 3: calcining the filter residue obtained in step 2 once, during which the calcination temperature is 700° C. and the time is 2 h to obtain crude indium oxide;

[0054] Subsequently, the crude indium oxide is mixed with a reducing agent and subjected to secondary calcination. During the secondary calcination, the calcination temperature is 1000° C. and the time is 4 hours to obtain metallic indium.

[0055] The flocculant is polyacrylamide, and the mass ratio of the flocculant to the intermediate liquid is 5:100;

[0056] The reducing agent is coke, and the mass ratio of the crude indium oxide to the reducing agent is 5:1.

[0057] Example 3

[0058] Step 1: adding an alkaline solution to an indium-containing acidic waste liquid (taken from the same source as in Example 1) until the pH is 11 to obtain an intermediate solution 1;

[0059] Step 2: adding a flocculant to the intermediate solution 1 obtained in step 1, followed by filter pressing to obtain a filter residue;

[0060] The indium ion content in the intermediate solution 1 remaining after the filter press was tested, and the results showed that the indium ion content in the intermediate solution 1 remaining after the filter press was 353 ppm.

[0061] Step 3: calcining the filter residue obtained in step 2 once, during which the calcination temperature is 500° C. and the time is 4 hours to obtain crude indium oxide;

[0062] Subsequently, the crude indium oxide is mixed with a reducing agent and subjected to secondary calcination. During the secondary calcination, the calcination temperature is 800° C. and the time is 5 hours to obtain metallic indium.

[0063] The flocculant is polyacrylamide, and the mass ratio of the flocculant to the intermediate liquid is 3:100;

[0064] The reducing agent is anthracite, and the mass ratio of the crude indium oxide to the reducing agent is 1:1.

[0065] Example 4

[0066] The method is substantially the same as Example 1, except that the same mass of polyaluminium chloride is used instead of polyacrylamide;

[0067] At the same time, the indium ion content in the remaining intermediate liquid 1 after the filter press was tested, and the results showed that the indium ion content in the remaining intermediate liquid 1 after the filter press was 361 ppm.

[0068] Example 5

[0069] The method is basically the same as Example 1, except that the flocculant is a mixture of polyacrylamide and polyaluminium chloride, and the mass ratio of polyacrylamide to polyaluminium chloride is 3:1;

[0070] At the same time, the indium ion content in the remaining intermediate solution 1 after the filter press was tested, and the results showed that the indium ion content in the remaining intermediate solution 1 after the filter press was 313 ppm.

[0071] Example 6

[0072] The method is basically the same as Example 1, except that the flocculant is a mixture of polyacrylamide and polyaluminium chloride, and the mass ratio of polyacrylamide to polyaluminium chloride is 1:1;

[0073] At the same time, the indium ion content in the remaining intermediate solution 1 after the filter press was tested, and the results showed that the indium ion content in the remaining intermediate solution 1 after the filter press was 302 ppm.

[0074] Example 7

[0075] The method is basically the same as Example 1, except that the flocculant is a mixture of polyacrylamide and polyaluminium chloride, and the mass ratio of polyacrylamide to polyaluminium chloride is 2:1;

[0076] At the same time, the indium ion content in the remaining intermediate solution 1 after the filter press was tested, and the results showed that the indium ion content in the remaining intermediate solution 1 after the filter press was 248 ppm.

[0077] Example 8

[0078] Step 1: adding an alkaline solution to an indium-containing acidic waste liquid (taken from the same source as in Example 1) until the pH is 8 to obtain an intermediate solution 1;

[0079] Step 2: adding a flocculant to the intermediate solution 1 obtained in step 1, followed by filter pressing to obtain a filter residue;

[0080] At the same time, the indium ion content in the remaining intermediate solution 1 after the filter press was tested, and the results showed that the indium ion content in the remaining intermediate solution 1 after the filter press was 348ppm;

[0081] Step 3: calcining the filter residue obtained in step 2 once, during which the calcination temperature is 300° C. and the time is 6 hours to obtain crude indium oxide;

[0082] Subsequently, the crude indium oxide is mixed with a reducing agent and a slag-forming agent, and is subjected to secondary calcination. During the secondary calcination, the calcination temperature is 600° C. and the time is 6 hours to obtain metallic indium;

[0083] The flocculant is polyacrylamide, and the mass ratio of polyacrylamide to the intermediate liquid is 1:100;

[0084] The reducing agent is graphite powder;

[0085] The slag-forming agent is quartz;

[0086] The mass ratio of crude indium oxide, reducing agent and slag-forming agent is 3:1:4.

[0087] Example 9

[0088] The method is basically the same as Example 1, except that step 3 specifically comprises: calcining the filter residue obtained in step 2 once, wherein the calcination temperature is 200° C. and the calcination time is 7 h to obtain crude indium oxide;

[0089] Subsequently, the crude indium oxide is mixed with a reducing agent and subjected to secondary calcination. During the secondary calcination, the calcination temperature is 500° C. and the time is 7 hours to obtain metallic indium;

[0090] The indium ion content in the intermediate solution 1 remaining after the filter press was tested, and the results showed that the indium ion content in the intermediate solution 1 remaining after the filter press was 356 ppm.

[0091] Example 10

[0092] The method is basically the same as Example 1, except that step 3 specifically comprises: calcining the filter residue obtained in step 2 once, wherein the calcination temperature is 800° C. and the calcination time is 1 h to obtain crude indium oxide;

[0093] Subsequently, the crude indium oxide is mixed with a reducing agent and subjected to secondary carbothermal reduction. During the secondary carbothermal reduction, the calcination temperature is 1100° C. and the time is 3 h to obtain metallic indium.

[0094] The indium ion content in the intermediate solution 1 remaining after the filter press was tested, and the results showed that the indium ion content in the intermediate solution 1 remaining after the filter press was 352 ppm.

[0095] Comparative Example 1

[0096] The method is substantially the same as Example 1, except that, step 1 specifically comprises adding an alkaline solution to an indium-containing acidic waste liquid (taken from the same source as in Example 1) until the pH value is 7 to obtain an intermediate solution 1;

[0097] At the same time, the indium ion content in the remaining intermediate solution 1 after the filter press was tested, and the results showed that the indium ion content in the remaining intermediate solution 1 after the filter press was 874 ppm.

[0098] Comparative Example 2

[0099] The method is basically the same as Example 1, except that the flocculant is ferric sulfate;

[0100] At the same time, the indium ion content in the remaining intermediate solution 1 after the filter press was tested, and the results showed that the indium ion content in the remaining intermediate solution 1 after the filter press was 758 ppm.

[0101] Comparative Example 3

[0102] The method is basically the same as Example 1, except that the flocculant is aluminum sulfate;

[0103] At the same time, the indium ion content in the remaining intermediate solution 1 after the filter press was tested, and the results showed that the indium ion content in the remaining intermediate solution 1 after the filter press was 723 ppm.

[0104] Performance Testing

[0105] 1. Test the recovery rate of indium. The specific method is: use ICP-MS mass spectrometer to measure the content of indium in the recovered liquid to determine the recovery rate of indium;

[0106] The recovery rate is calculated as follows: Recovery rate = (the content of indium ions in the indium-containing acidic waste liquid - the content of indium ions in the intermediate solution remaining after filter pressing) / the content of indium ions in the indium-containing acidic waste liquid × 100%

[0107] The test results are shown in Table 1:

[0108] Table 1

[0109]

[0110]

[0111] 2. Use an energy spectrometer to test the oxygen content of metal indium. The results are shown in Table 2:

[0112] Table 2

[0113]

[0114] Result analysis:

[0115] 1. In combination with Table 1-2, it can be seen from Examples 1-3 that when the relevant parameters in the metal indium recovery process are slightly adjusted, although the indium recovery rates between Examples 1-3 fluctuate to a certain extent, the overall fluctuation range is small;

[0116] 2. It can be seen from Examples 1 and 4 that when polyaluminium chloride is used instead of polyacrylamide, the indium recovery rate of Example 4 shows a very small downward trend relative to Example 1. Further observation of Examples 5-7 shows that when polyacrylamide and polyaluminium chloride are used to prepare the flocculant, the flocculation effect of Examples 5-7 is significantly improved relative to Examples 1 and 4.

[0117] And it can be seen from the observation of Examples 5-7 that when the mass ratio of polyacrylamide to polyaluminium chloride in Example 7 is 2:1, the recovery rate of indium is particularly outstanding, and the flocculant at this mass ratio produces a more excellent flocculation effect;

[0118] 3. Combined with Table 1-2, it can be seen from Example 1 and Example 8 that during the secondary calcination of metallic indium, although the addition of slag-forming agent cannot improve the recovery rate of indium, it has a significant inhibitory effect on the oxygen content in metallic indium. Figure 1-4 , the EDS spectrum of metal indium with slag-forming agent added shows that, Figure 1-2 Its surface is smoother when slag-forming agent is added;

[0119] 4. It can be seen from Example 1 and Comparative Example 1 that when the pH value of the intermediate solution 1 after the alkaline solution is added is changed, the indium recovery rate of Comparative Example 1 is significantly reduced. After analysis, the reason for this phenomenon is that the pH value of the intermediate solution 1 is too low, resulting in a large amount of indium still existing in the solution in the form of ions and unable to precipitate, which leads to a decrease in the recovery rate;

[0120] 5. It can be seen from Example 1 and Comparative Examples 2-3 that after the flocculant is replaced, the indium recovery rates of the two methods show a significant downward trend compared with Example 1. The reason is that after the flocculant is replaced, the indium metal with small particle size cannot be completely flocculated, which leads to a decrease in the indium recovery rate.

[0121] 6. It can be seen from Example 1 and Examples 9-10 that when the calcination temperature or calcination time in the primary calcination and secondary calcination processes is greatly changed, although Comparative Examples 4 and 5 still have a high indium recovery rate, the oxygen content of both is too high.

[0122] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

Claims

1. A method for recovering indium from indium-containing acidic waste liquid, It is characterized in that The following steps are involved: Step 1: adding an alkaline solution to the indium-containing acidic waste liquid until the pH is 8 to 14 to obtain an intermediate solution 1; Step 2: adding a flocculant to the intermediate solution 1 obtained in step 1, followed by filter pressing to obtain a filter residue; Step 3: calcining the filter residue obtained in step 2 once to obtain crude indium oxide, then mixing the crude indium oxide with a reducing agent, and calcining it twice to obtain metallic indium; The flocculant is selected from at least one of polyacrylamide, polyaluminium chloride, polyferric sulfate, polyferrous sulfate and polyaluminium sulfate; The reducing agent is selected from at least one of graphite powder, coke and anthracite.

2. The method for recovering indium from indium-containing acidic waste liquid according to claim 1, It is characterized in that The flocculant is a mixture of polyacrylamide and polyaluminium chloride, and the mass ratio of polyacrylamide to polyaluminium chloride is 1 to 3:

1.

3. The method for recovering indium from indium-containing acidic waste liquid according to claim 1, It is characterized in that In step 2, the mass ratio of flocculant to intermediate liquid 1 is 1 to 5:

100.

4. The method for recovering indium from indium-containing acidic waste liquid according to claim 1, It is characterized in that The reducing agent is graphite powder, and in step 3, the mass ratio of crude indium oxide to the reducing agent is 1 to 5:

1.

5. The method for recovering indium from indium-containing acidic waste liquid according to claim 1, It is characterized in that The mass of indium ions in the indium-containing acidic waste liquid is at least 90% of the total mass of metal ions.

6. The method for recovering indium from indium-containing acidic waste liquid according to claim 1, It is characterized in that During the primary calcination process, the calcination temperature is 300-700°C and the time is 2-6 hours.

7. The method for recovering indium from indium-containing acidic waste liquid according to claim 1, It is characterized in that During the secondary calcination process, the calcination temperature is 600-1000°C and the time is 4-6 hours.

8. The method for recovering indium from indium-containing acidic waste liquid according to claim 1, It is characterized in that The step 3 specifically comprises: calcining the filter residue obtained in step 2 once to obtain crude indium oxide, then mixing the crude indium oxide with a reducing agent and a slag-forming agent, and calcining twice to obtain metallic indium; The slag-forming agent is selected from at least one of quartz, borax and sodium carbonate; The mass ratio of the crude indium oxide, the reducing agent and the slag-forming agent is 1-5:1:

4.

9. The method for recovering indium from indium-containing acidic waste liquid according to claim 1, It is characterized in that The indium recovery rate of the method for recovering indium from indium-containing acidic waste liquid is greater than or equal to 90%.

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