Method for purifying indium

Abstract

The invention provides a method for purifying indium, and belongs to the technical field of metallurgy. The method for purifying indium comprises the following steps: firstly, carrying out alkaline smelting on crude indium, sodium hydroxide and an additive, then carrying out chlorination refining on a first indium ingot and indium chloride, and then carrying out oxygen-enriched blowing on a second indium ingot, so that four metal impurities of Sn, Sb, Pb and Bi in the crude indium can be deeply removed, the purity of the obtained refined indium is greater than or equal to 3N5, and the contents of the four metal impurities of Pb, Sb, Sn and Bi in the refined indium are all less than 0.1%.

Description

Technical Field

[0001] The present application relates to the field of metallurgy technology, and in particular to a method for purifying indium. Background Art

[0002] Metal indium is mainly used as a raw material for manufacturing low-melting alloys, bearing alloys, semiconductors, electric light sources, etc. High-purity indium is a single element of indium with a purity of 99.999%, which is mainly used to make semiconductor compounds, high-purity alloys and dopants for semiconductor materials. In recent years, the application of metal indium has become more and more extensive, and the industry's requirements for the purity of metal indium have become higher and higher.

[0003] Existing purification methods include chemical precipitation, extraction, distillation, electrolysis, etc. The most widely used method is electrolysis + vacuum distillation, but the production process is very complicated, easy to pollute and affect the purity of indium, and the electrolyte needs to be constantly replaced, which affects production efficiency. In addition, the purity is not high and it is difficult to meet market demand.

[0004] The raw materials for preparing high-purity indium are mostly 2N crude indium. However, the four metal impurities Sn, Sb, Pb, and Bi in crude indium are difficult to remove using the above purification methods, resulting in a large impurity removal load in the back-end purification process of the indium ingot. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for purifying indium.

[0006] To achieve the above object, the technical solution adopted by the present disclosure is: a method for purifying indium is provided, comprising the following steps:

[0007] Smelting crude indium, sodium hydroxide and additives, cooling the obtained first melt to obtain a first indium ingot;

[0008] The first indium ingot and indium chloride are subjected to a chlorination reaction, and the obtained second melt is cooled to obtain a second indium ingot;

[0009] The second indium ingot is subjected to oxygen-enriched blowing, and the obtained third melt is cooled to obtain refined indium;

[0010] The additive is at least one of phosphorus pentoxide, sodium nitrate, sodium carbonate, carbon powder, potassium carbonate and silicon dioxide.

[0011] In some embodiments, the mass of the additive is 5-10% of the mass of the crude indium.

[0012] In some embodiments, the mass of the sodium hydroxide is 50-60% of the mass of the crude indium.

[0013] In some embodiments, the smelting temperature is 400-600° C. and the smelting time is 3-6 hours.

[0014] In some embodiments, the mass of the indium chloride is 10-15% of the mass of the first indium ingot.

[0015] In some embodiments, the chlorination reaction is carried out at a temperature of 300-400° C. and a time of 1-2 h.

[0016] In some embodiments, the oxygen-enriched blowing is carried out at a temperature of 250-350° C. and for a time of 30-60 min.

[0017] In some embodiments, the oxygen rate of the oxygen-enriched blowing is 0.1-0.5 L / min.

[0018] In some embodiments, before the cooling, the step further includes removing scum on the surfaces of the first melt, the second melt, and the third melt.

[0019] In some embodiments, the purity of the refined indium is ≥3N5.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention first performs alkaline smelting on crude indium, sodium hydroxide and additives, then performs chlorination refining on the first indium ingot and indium chloride, and then performs oxygen-enriched blowing on the second indium ingot, so as to deeply remove the four metal impurities Sn, Sb, Pb and Bi in the crude indium, so that the purity of the obtained refined indium is ≥3N5, and the contents of the four metal impurities Pb, Sb, Sn and Bi in the refined indium are all less than 0.1%.

[0021] The process adopted in the present invention can purify crude indium, with an indium metal loss of less than 0.5%. The crude indium is purified to 3N5 indium with a qualified rate of more than 99%. The process operation is simple and suitable for industrial production.

[0022] The process formula adopted by the present invention does not generate waste water or waste gas, and the generated byproduct scum can be sold as an indium-containing material for a second time, with less equipment investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The present invention is a process flow chart of the method for purifying indium. DETAILED DESCRIPTION

[0024] In order to facilitate understanding of the present disclosure, the present disclosure will be described more fully below. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present disclosure more thorough and comprehensive.

[0025] As used herein:

[0026] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0027] The conjunction "consisting of excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed-ended so that it does not include materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0028] When amount, concentration or other value or parameter is represented by range, preferred range or a series of upper preferred value and lower preferred value, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value and any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when disclosing range "1-5", described range should be interpreted as including range "1-4", "1-3", "1-2", "1-2 and 4-5", "1-3 and 5" etc. When numerical range is described in this article, unless otherwise stated, the range is intended to include its end value and all integers and fractions within the range.

[0029] In these examples, parts and percentages are by mass unless otherwise indicated.

[0030] "Parts by mass" refers to the basic unit of measurement for expressing the mass ratio of multiple components. 1 part can represent any unit mass, such as 1g or 2.689g. If we say that the mass of component A is a parts and the mass of component B is b parts, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it means that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number, indicating a multiple factor). It should not be misunderstood that, unlike the mass parts, the sum of the mass of all components is not limited to 100 parts.

[0031] “And / or” is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0032] In order to remove various metal impurities such as Sn, Sb, Pb, Bi, etc. in crude indium, the present invention provides a method for purifying indium, comprising the following steps:

[0033] Smelting crude indium, sodium hydroxide and additives, cooling the obtained first melt to obtain a first indium ingot;

[0034] The first indium ingot and indium chloride are subjected to a chlorination reaction, and the obtained second melt is cooled to obtain a second indium ingot;

[0035] The second indium ingot is subjected to oxygen-enriched blowing, and the obtained third melt is cooled to obtain refined indium;

[0036] The additive is at least one of phosphorus pentoxide, sodium nitrate, sodium carbonate, carbon powder, potassium carbonate and silicon dioxide.

[0037] The present invention firstly performs alkaline smelting on crude indium, sodium hydroxide and additives, then performs chlorination refining on the first indium ingot and indium chloride, and then performs oxygen-enriched blowing on the second indium ingot, so as to deeply remove four metal impurities of Sn, Sb, Pb and Bi in the crude indium, and make the purity of the obtained refined indium ≥3N5.

[0038] Taking phosphorus pentoxide as an additive as an example, the main reaction equation of alkaline smelting is:

[0039] 2MeO+2NaOH+P 2 O 5 =2NaMePO 4 +H 2 Oh,

[0040] 2Me+2xNaOH=2NaMeO x +H 2 ↑,

[0041] Me+H 2 O=MeO+H 2 ↑,

[0042] MeO + 2xNaOH = 2Na 2 MeO x +xH 2 O;

[0043] The main reaction equation of chlorination refining is:

[0044] 3Me+xInCl 3 =xIn+3MeCl x ;

[0045] The main reaction equation of oxygen-enriched blowing is:

[0046] 2Me+O 2 =2MeO;

[0047] Me in the reaction equation is a metal impurity such as Sn, Pb, Sb, Bi, etc.

[0048] In some embodiments, the additives are phosphorus pentoxide and silicon dioxide, and the mass ratio of phosphorus pentoxide to silicon dioxide is 1-7:1; for example, it can be but not limited to 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1.

[0049] In some embodiments, the mass of the additive is 5-10% of the mass of crude indium; for example, it can be but not limited to 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%.

[0050] In some embodiments, the mass of the sodium hydroxide is 50-60% of the mass of the crude indium; for example, it can be but not limited to 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%.

[0051] The quality of additives and / or sodium hydroxide will affect the purity of refined indium. If the quality of additives and / or sodium hydroxide is too low or too high, the purity of refined indium will be low.

[0052] In some embodiments, the smelting temperature is 400-600°C, for example, it can be but not limited to 400°C, 420°C, 440°C, 460°C, 480°C, 500°C, 520°C, 540°C, 560°C, 580°C, 600°C; the time is 3-6h, for example, it can be but not limited to 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h.

[0053] The above smelting temperature and time can make the metal impurities in the crude indium fully react with the additive and the sodium hydroxide.

[0054] In some embodiments, the mass of the indium chloride is 10-15% of the mass of the first indium ingot; for example, it can be but not limited to 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%.

[0055] The quality of indium chloride will affect the purity of refined indium. If the quality of indium chloride is too low or too high, the purity of refined indium will be low.

[0056] In some embodiments, the chlorination reaction temperature is 300-400°C, for example, but not limited to 300°C, 320°C, 340°C, 360°C, 380°C, 400°C; the time is 1-2h, for example, but not limited to 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2h.

[0057] The temperature and time of the chlorination reaction can allow the metal impurities in the first indium ingot to fully react with indium chloride.

[0058] In some embodiments, the temperature of the oxygen-enriched blowing is 250-350°C, for example, it can be but not limited to 250°C, 270°C, 290°C, 310°C, 330°C, 350°C; the time is 30-60min, for example, it can be but not limited to 30min, 35min, 40min, 45min, 50min, 55min, 60min.

[0059] In some embodiments, the oxygen rate of the oxygen-enriched blowing is 0.1-0.5 L / min, for example, but not limited to 0.1 L / min, 0.2 L / min, 0.3 L / min, 0.4 L / min, 0.5 L / min.

[0060] The temperature and time of the oxygen-enriched blowing process can allow the metal impurities in the second indium ingot to fully react with oxygen.

[0061] In some embodiments, before the cooling, the step further includes removing scum on the surfaces of the first melt, the second melt, and the third melt.

[0062] Removing scum on the surfaces of the first melt, the second melt and the third melt can achieve a better purification effect of crude indium.

[0063] Specifically, in the process of removing the scum on the surface of the second melt, ventilation is performed at the same time, and the obtained ventilation rate is 4-6 m / s. Ventilation can remove toxic gases generated by the chlorination reaction and improve the safety of indium purification.

[0064] In some embodiments, the purity of the refined indium is ≥3N5, specifically 3N5-4N; for example, it can be but not limited to 3N5, 3N6, 3N7, 3N8, 3N, 4N.

[0065] In the following embodiments and comparative examples, the crude indium is a 2N indium ingot, which includes the following components by mass percentage: In: 98%, Pb: 0.3%, Sn: 0.63%, Sb: 0.45%, Bi: 0.3%, and the total amount of other impurity metals is 0.32%.

[0066] Example 1

[0067] This embodiment provides a method for purifying indium, comprising the following steps:

[0068] S1: Put a 2N indium ingot, sodium hydroxide and an additive into a cylindrical graphite crucible, place it in a muffle furnace, and smelt it at 400°C for 2 hours. After 30 minutes, remove the surface scum of the first melt. The total smelting time is 6 hours. After the smelting is completed, cool it naturally to obtain a first indium ingot; wherein the mass of sodium hydroxide is 55% of the mass of the 2N ingot, and the additive is phosphorus pentoxide, and the mass of the additive is 5% of the mass of the 2N ingot;

[0069] S2: placing the first indium ingot and indium chloride in an induction medium frequency furnace with a graphite inner tank, adjusting the heating power of the induction medium frequency furnace to 15kW / h, reacting at a temperature of 400°C for 1h, removing the surface scum of the second melt after the reaction is completed, and turning on the exhaust system at the same time, exhausting at a rate of 5m / s until there is no obvious pungent smell in the working environment, and then closing the exhaust hood; cooling naturally to obtain a second indium ingot; wherein the mass of indium chloride is 15% of the mass of the first indium ingot;

[0070] S3: Place the second indium ingot into a bottom resistance wire heated graphite crucible, insert the titanium tube into the second indium ingot, introduce oxygen at a rate of 0.3L / min, react at 300°C for 45min, remove the surface slag of the third melt after the reaction is completed, cool naturally, and obtain refined indium.

[0071] Example 2

[0072] This embodiment provides a method for purifying indium, comprising the following steps:

[0073] S1: Put a 2N indium ingot, sodium hydroxide and an additive into a cylindrical graphite crucible, place it in a muffle furnace, and smelt it at a temperature of 500°C for 2 hours. After an interval of 30 minutes, remove the surface scum of the first melt. The smelting is 4 hours in total. After the smelting is completed, cool it naturally to obtain a first indium ingot; wherein the mass of sodium hydroxide is 50% of the mass of the 2N ingot, and the additive is phosphorus pentoxide, and the mass of the additive is 10% of the mass of the 2N ingot;

[0074] S2: placing the first indium ingot and indium chloride in an induction medium frequency furnace with a graphite inner tank, adjusting the heating power of the induction medium frequency furnace to 15kW / h, reacting at a temperature of 350°C for 1.5h, removing the surface scum of the second melt after the reaction, and turning on the exhaust system at the same time, exhausting at a rate of 4m / s until there is no obvious pungent smell in the working environment, and then closing the exhaust hood; cooling naturally to obtain a second indium ingot; wherein the mass of indium chloride is 13% of the mass of the first indium ingot;

[0075] S3: Place the second indium ingot into a bottom resistance wire heated graphite crucible, insert the titanium tube into the second indium ingot, introduce oxygen at a rate of 0.1L / min, react at 250°C for 60min, remove the surface slag of the third melt after the reaction is completed, cool naturally, and obtain refined indium.

[0076] Example 3

[0077] This embodiment provides a method for purifying indium, comprising the following steps:

[0078] S1: Put 2N indium ingot, sodium hydroxide and additive into a cylindrical graphite crucible, place it in a muffle furnace, smelt it at 600°C for 1 hour, remove the surface scum of the first melt after 30 minutes, and smelt it for a total of 3 hours. After the smelting is completed, cool it naturally to obtain the first indium ingot; wherein, the mass of sodium hydroxide is 60% of the mass of the 2N ingot, and the additive is phosphorus pentoxide, and the mass of the additive is 15% of the mass of the 2N ingot;

[0079] S2: placing the first indium ingot and indium chloride in an induction medium frequency furnace with a graphite inner tank, adjusting the heating power of the induction medium frequency furnace to 15kW / h, reacting at a temperature of 300°C for 2h, removing the surface scum of the second melt after the reaction is completed, and turning on the exhaust system at the same time, exhausting at a rate of 6m / s until there is no obvious pungent smell in the working environment, and then closing the exhaust hood; cooling naturally to obtain a second indium ingot; wherein the mass of indium chloride is 10% of the mass of the first indium ingot;

[0080] S3: Place the second indium ingot into a bottom resistance wire heated graphite crucible, insert the titanium tube into the second indium ingot, introduce oxygen at a rate of 0.5L / min, react at 350°C for 30min, remove the surface slag of the third melt after the reaction is completed, cool naturally, and obtain refined indium.

[0081] Example 4

[0082] This embodiment provides a method for purifying indium, which differs from the method for purifying indium in Example 2 only in that the additives in this embodiment are phosphorus pentoxide and silicon dioxide, and the mass ratio of phosphorus pentoxide to silicon dioxide is 3:1; the remaining steps and parameters are the same as those in Example 2.

[0083] Example 5

[0084] This embodiment provides a method for purifying indium, which differs from the method for purifying indium in Example 2 only in that the additives in this embodiment are phosphorus pentoxide and silicon dioxide, and the mass ratio of phosphorus pentoxide to silicon dioxide is 1:1; the remaining steps and parameters are the same as those in Example 2.

[0085] Example 6

[0086] This embodiment provides a method for purifying indium, which differs from the method for purifying indium in Example 2 only in that the additives in this embodiment are phosphorus pentoxide and silicon dioxide, and the mass ratio of phosphorus pentoxide to silicon dioxide is 4:1; the remaining steps and parameters are the same as those in Example 2.

[0087] Example 7

[0088] This embodiment provides a method for purifying indium, which differs from the method for purifying indium in Example 2 only in that the additives in this embodiment are phosphorus pentoxide and silicon dioxide, and the mass ratio of phosphorus pentoxide to silicon dioxide is 7:1; the remaining steps and parameters are the same as those in Example 2.

[0089] Example 8

[0090] This embodiment provides a method for purifying indium, which differs from the method for purifying indium in Example 2 only in that the additives in this embodiment are phosphorus pentoxide and silicon dioxide, and the mass ratio of phosphorus pentoxide to silicon dioxide is 9:1; the remaining steps and parameters are the same as those in Example 2.

[0091] Example 9

[0092] This embodiment provides a method for purifying indium, which differs from the method for purifying indium in Example 2 only in that the additives in this embodiment are sodium carbonate, silicon dioxide and carbon powder, and the mass ratio of sodium carbonate, silicon dioxide and carbon powder is 5:2:3; the remaining steps and parameters are the same as those in Example 2.

[0093] Comparative Example 1

[0094] This comparative example provides a method for purifying indium, which differs from the method for purifying indium in Example 2 only in that: in step S1 of this comparative example, no additive is included; the remaining steps and parameters are the same as those in Example 2.

[0095] Comparative Example 2

[0096] This comparative example provides a method for purifying indium, which differs from the method for purifying indium in Example 2 only in that: in step S1 of this comparative example, the mass of the additive is 3% of the mass of the 2N indium ingot; the remaining steps and parameters are the same as those in Example 2.

[0097] Comparative Example 3

[0098] This comparative example provides a method for purifying indium, which differs from the method for purifying indium in Example 2 only in that: in step S1 of this comparative example, the mass of the additive is 12% of the mass of the 2N indium ingot; the remaining steps and parameters are the same as those in Example 2.

[0099] Comparative Example 4

[0100] This comparative example provides a method for purifying indium, which differs from the method for purifying indium in Example 2 only in that: in step S1 of this comparative example, the mass of sodium hydroxide is 45% of the mass of the 2N indium ingot; the remaining steps and parameters are the same as those in Example 2.

[0101] Comparative Example 5

[0102] This comparative example provides a method for purifying indium, which differs from the method for purifying indium in Example 2 only in that: in step S1 of this comparative example, the mass of sodium hydroxide is 65% of the mass of the 2N indium ingot; the remaining steps and parameters are the same as those in Example 2.

[0103] Comparative Example 6

[0104] This comparative example provides a method for purifying indium, which differs from the method for purifying indium in Example 2 only in that: in step S2 of this comparative example, the mass of indium chloride is 8% of the mass of the first indium ingot; the remaining steps and parameters are the same as those in Example 2.

[0105] Comparative Example 7

[0106] This comparative example provides a method for purifying indium, which differs from the method for purifying indium in Example 2 only in that: in step S2 of this comparative example, the mass of indium chloride is 17% of the mass of the first indium ingot; the remaining steps and parameters are the same as those in Example 2.

[0107] Comparative Example 8

[0108] This comparative example provides a method for purifying indium, which differs from the method for purifying indium in Example 2 only in that this comparative example does not include step S2 and step S3, and the remaining steps and parameters are the same as those in Example 2.

[0109] Comparative Example 9

[0110] This comparative example provides a method for purifying indium, which differs from the method for purifying indium in Example 2 only in that this comparative example does not include step S2, and the remaining steps and parameters are the same as those in Example 2.

[0111] Comparative Example 10

[0112] This comparative example provides a method for purifying indium, which differs from the method for purifying indium in Example 2 only in that this comparative example does not include step S3, and the remaining steps and parameters are the same as those in Example 2.

[0113] The components of the refined indium products obtained in Examples 1-9 and Comparative Examples 1-10 were analyzed by chemical detection analysis using ICP-OES. The analysis results are shown in Table 1.

[0114] Table 1

[0115]

[0116]

[0117] It can be seen from the experimental data in Table 1 that the purity of the refined indium product is ≥99.5% by using the method for purifying indium of the present invention, which indicates that the method for purifying indium of the present invention has a good purification effect.

[0118] By comparing Example 2 with Examples 4-9, it can be seen that when the additives are phosphorus pentoxide and silicon dioxide, the purity of the obtained refined indium product is ≥99.9%; further, when the mass ratio of phosphorus pentoxide and silicon dioxide is 1-7:1, the purity of the obtained refined indium product is ≥99.95%, indicating that in the present invention, when the additives are phosphorus pentoxide and silicon dioxide, the purification effect of the method for purifying indium is good, and when the mass ratio of phosphorus pentoxide and silicon dioxide is 1-7:1, the purification effect of the method for purifying indium is better.

[0119] By comparing Example 2 with Comparative Examples 1-10, it can be seen that when any step in the method for purifying indium is missing or any parameter is not within the scope of the present invention, such as the amount of additives added, the amount of sodium hydroxide added, the amount of indium chloride added, etc., the purity of the refined indium product will decrease.

[0120] Finally, it should be noted that the above embodiments are used to illustrate the technical solution of the present disclosure rather than to limit the protection scope of the present disclosure. Although the present disclosure has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present disclosure can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present disclosure.

Claims

1. A method for purifying indium, characterized in that: The following steps are involved: Smelting crude indium, sodium hydroxide and additives, cooling the obtained first melt to obtain a first indium ingot; The first indium ingot and indium chloride are subjected to a chlorination reaction, and the obtained second melt is cooled to obtain a second indium ingot; The second indium ingot is subjected to oxygen-enriched blowing, and the obtained third melt is cooled to obtain refined indium; The additive is at least one of phosphorus pentoxide, sodium nitrate, sodium carbonate, carbon powder, potassium carbonate and silicon dioxide.

2. The method for purifying indium according to claim 1, characterized in that: The mass of the additive is 5-10% of the mass of the crude indium.

3. The method for purifying indium according to claim 1, characterized in that: The mass of the sodium hydroxide is 50-60% of the mass of the crude indium.

4. The method for purifying indium according to claim 1, characterized in that: The smelting temperature is 400-600°C and the smelting time is 3-6h.

5. The method for purifying indium according to claim 1, characterized in that: The mass of the indium chloride is 10-15% of the mass of the first indium ingot.

6. The method for purifying indium according to claim 1, characterized in that: The temperature of the chlorination reaction is 300-400° C. and the time is 1-2 hours.

7. The method for purifying indium according to claim 1, characterized in that: The temperature of the oxygen-enriched blowing is 250-350° C., and the time is 30-60 minutes.

8. The method for purifying indium according to claim 1, characterized in that: The oxygen rate of the oxygen-enriched blowing is 0.1-0.5 L / min.

9. The method for purifying indium according to claim 1, characterized in that: Before the cooling, the method further includes removing scum on the surfaces of the first melt, the second melt and the third melt.

10. The method for purifying indium according to claim 1, characterized in that: The purity of the refined indium is ≥3N5.

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