JPS5831049A - Collecting method of high purity indium from sulfuric acid acidic solution containing indium - Google Patents

Abstract

PURPOSE:To collect In of high purity with high efficiency by use of a comparatively simple device, by adding NH4Cl to coarse In obtained by cementation from a sulfuric acid acidic solution containing In, heating and melting it, and separating the dross. CONSTITUTION:To a sulfuric acid acidic solution containing In, alkali is added, its pH is set to 0.5-1.2, and to In in this solution, Zn-Cd alloy powder of 1- 1.3 equivalent or Zn powder of high purity is added, by which cementation is executed. As a result, coarse In obtained by deposition and separation is melted in thick hydrochloric acid, cementation is executed by soaking an In plate into said hydrochloric acid, a precious metal is deposited and separated from the In, and after that, deposit containing In is obtained by executing the same cementation as the process in which said coarse In has been obtained, it is melted by alkali, and coarse In is obtained. Subsequently, NH4Cl being >=2wt% by external division is added to said coarse In, it is heated and melted, generated dross is separated, and In of purity being >= about 99.99wt% is obtained with actual yield being >= about 85%.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recovering indium from a smelting intermediate containing indium, and more specifically, a method for recovering indium from a smelting intermediate containing indium. The present invention relates to a method for efficiently recovering high-purity indium from a smelting intermediate from an aqueous solution leached with an aqueous sulfuric acid solution.

Originally, there is no ore for the purpose of recovering indium.1 It is usually contained in trace amounts in zinc ores, and indium is recovered from the residue etc. from the electrolysis of zinc in the lead source that is generated when recovering cadmium. things are being done.

The conventional method for recovering indium from the above-mentioned indium raw materials is, when the raw material is a lead source, the first method is to leach the lead source with a sulfuric acid aqueous solution, and the resulting indium-containing aqueous solution is leached with an alkali hydroxide solution. After neutralizing with water and precipitating indium, it is separated from the aqueous solution, and then this precipitate is redissolved in an aqueous sulfuric acid solution to form an aqueous solution of crude indium sulfate, and cadmium metal powder is added to this to perform cementation. Precipitate crude indium. The resulting sponge-like crude indium is separated and dissolved in a sulfuric acid solution.
9, perform water extraction after roasting with sulfuric acid at about 750C, separate the undissolved liquid and dissolve it in an aqueous sulfuric acid solution, then add alkali to this aqueous solution to adjust the pH to 4 to 4.5 to form a precipitate, and separate. There is a method of recovering indium by dissolving the precipitate again in an aqueous sulfuric acid solution and treating it with an electrolytic method.

The second method is to add sulfide to an aqueous solution in which a lead source is leached with an aqueous sulfuric acid solution to carry out a so-called sulfurization treatment, to separate the produced nonasulfides, and to neutralize them by adding alkali hydroxide to the pressurized aqueous solution. After separating the formed precipitate, this precipitate was dissolved in an aqueous solution of hydrochloric acid, and sulfide was added thereto again for sulfurization treatment. Similar methods have been proposed, including cementation, acid dissolution, alkali addition, precipitation separation, sulfuric acid dissolution, and electrowinning to obtain high-purity indium.

If the raw material is a residue from zinc hydrometallurgical smelting, in the third method, when the raw material is placed in a lead blast furnace and heat treated, indium is converted into lead and silver. Fuming this trowel,
The dust generated at this time is treated in a lead blast furnace as described above. When the lead content is oxidized, indium is concentrated in the dross, so the dross is reduced in an electric furnace, and the lead containing indium is electrolyzed by the Benz method. Indium remains in the anode mud. This anode mud is treated by a sulfuric acid roasting method and then extracted with water, and the insoluble residue is dissolved in an aqueous sulfuric acid solution, and zinc powder is added to an aqueous solution to precipitate sponge-like indium. In this method, the indium thus obtained is further electrolytically refined to obtain highly pure indium.

As a fourth method, Ni! containing indium! # An aqueous solution obtained by leaching the hydrometallurgical residue with an aqueous sulfuric acid solution is subjected to sulfurization treatment in the same manner as in the second method, and then the P solution is subjected to solvent extraction using tributyl phosphate, and then back-extracted with water. After adjusting the pH of the pressurized water solution as necessary, zinc powder is added and cementation/cheeseing is performed to obtain sponge-like indium.Then, the above indium is melted with alkali hydroxide to obtain crude indium, and the following is the first method. Similarly, a method of electrowinning has been proposed.

However, all of these recovery methods employ undesirable sulfurization, electrolysis, or solvent extraction methods to obtain high-purity indium, and have disadvantages such as the need for large equipment and double-track operations. There was a strong need for a simple and reliable method to recover high-purity indium.

An object of the present invention is to eliminate the above-mentioned drawbacks and provide a method for reliably recovering high-purity indium using a relatively simple device. That is, an alkali is added to an acidic aqueous solution containing indium to adjust the pH to 0.5 to 1.2, and a zinc-cadonium alloy or zinc powder is added to this in an amount of 1.0 to 1.3 equivalents based on the amount of indium. Then, the crude indium obtained is poured into an aqueous solution of pH 1 or less dissolved in hydrochloric acid to precipitate and separate metals nobler than indium. , 5 to 1.2, add 0.9 to 1.1 equivalents of zinc-cadmium or zinc powder to the amount of indium, perform cementation, and melt the crude indium with sodium hydroxide. to remove dross, then add crude indicum to 11 or 90
After heating at 0 to 1050C, add 2% by weight or more, preferably 2 to 5% by weight of ammonium chloride, based on the amount of indium, and dross to obtain high purity (99,99%).
This is a method for recovering indium (more than % by weight).

The reason why the pH during the above-mentioned cementation is set in the range of 0.5 to 1.2 is that efficient cementation cannot be performed otherwise. and the amounts of zinc and cadmium or zinc added in the third step were 1.0 to 1.3 equivalents and 0.9 to 1.1 equivalents, respectively.
The reason why the former is defined as equivalent is that if the former is less than 1.0, the yield of indium will be poor, and if it is more than 1.3, the purity will similarly be reduced.

The lower limit of the latter addition was set at 0.9 to improve the purity of the obtained indium, and the upper limit was also set at 1.1 for the same reason. The pH during reverse cementation (precipitating impurities) is 1.
The reason why it is set to 0 or less is to efficiently remove impurities, and it is not limited to 41. -Also, the alkali used to adjust the pH is not particularly limited as long as it does not interfere with subsequent operations, but alkali hydroxide is preferred.

The choice of whether to heat the crude indium that has undergone cementation and alkaline melting treatment to a predetermined temperature or to move it to the next step is that if there are a lot of impurities such as cadmium, heat treatment is necessary, and the amount of heat treatment is small. This is because in some cases, this processing is not necessary. Processing temperature is 900-1050
C is appropriate.

If it is less than this, the separation of impurities will be poor, and if it is more than this, the yield of indium will decrease.

The amount of ammonium chloride added in the final knee is 2% by weight or more based on indium, preferably in the range of #i2 to 5% by weight. If the amount added is less than this, the removal of impurities will not be sufficient, and if it is added more than this, the quality of indium will not particularly improve and the yield may actually decrease.

The present invention will be explained in more detail below.

As the starting material of the present invention, any intermediate containing indium can be used, but here, a case will be described in which the raw material is powder, which is a by-product during cadmium smelting (Cd melting furnace).

As an example, when the soda water shown in Table 1 is placed in a rotating drum with water and treated, indium easily dissolves and is separated from the residue as an aqueous solution. A suspension similar to a solid substance is formed, so if this sediment is separated using an ordinary filter, the composition shown in Table 2 will be obtained. Add acid to pH 3.5
When adjusted to ~5.0, indium becomes hydroxide and precipitates, and most of Cd, Zn%PB can be separated by leaching.

The nine precipitates obtained here are separated from the aqueous solution, dissolved in 1+1 sulfuric acid in an equivalent amount or a slight excess of indium, and the undissolved residue is separated. . The residue at this time contains metallic Cd, Zn
In many cases, there is a large amount of indium present in the leachate, which causes cementation with indium in the leachate, so it is best to separate the indium from the residue as quickly as possible. In addition, in order to prevent the above-mentioned cementation, the pH of the aqueous solution should be adjusted to 0.1.
It is preferable to carry out in the range of -1.5. The composition of the sulfuric acid leachate thus obtained had a concentration composition as shown in Table 3 of Examples below, and the Ip concentration was about 8.5 t/.

Add a small amount of alkali to this leachate as necessary to adjust the pH.
After setting the pH to 0.5 to 1.2, preferably 1.0, Zn
Cementition is performed by adding 1.0 to 1.3 of -Cd alloy powder or JIS standard purest zinc ingot powder to the amount of indium. Zinc with poor purity, especially p
It is undesirable to use a material containing b, etc., as it will affect the purity of the precipitated indium.The indium obtained in the 0th order is dissolved in an amount of mineral acid, preferably dilute hydrochloric acid, in an amount sufficient to leach out the indium obtained. is adjusted to 1.0 or less, and a high purity indium plate is immersed in the aqueous solution to purify the solution. The amount of indium plate added is preferably such that its surface area is 5 d/aqueous solution (t) or more, and the immersion time is several hours, preferably 10 hours or more.

Gold nut, which is more dangerous than indium precipitated here, is normal r
Zn
-Cd alloy powder or zinc powder is added in an amount of 0.9 to 1 tl based on the amount of indium, and cementation is performed again to precipitate sponge-like indium.

The indium thus obtained is heated and melted by adding a predetermined amount of sodium hydroxide, and zinc and the like are removed as dross to obtain crude indium.

Indium obtained in this way can be used as is if there is a small amount of Cd etc., but if it is relatively large, it can be distilled using an open-top crucible tube at a temperature of 1000-1050 C1 and normal pressure. is separated by evaporation. The exhaust gas generated at this time is sucked out using a bag filter, etc. Next, the final step of adding ammonium chloride is carried out. In this case, the amount of ammonium chloride added is approximately 2% by weight based on indium, and this process is repeated several times to remove impurities. Removed as chlorinated dross. It can be heated at about 300 to 400C, which will not cause any problems to the gear.

By following the process described above, it is possible to recover indium, which is present in a very small amount in the raw material, as a metal with a purity of 99.99% by weight or more at an actual yield of 85N or more, and it is also a low-cost method. It can also be applied to all smelting intermediates containing indium, or to the purification of crude indium.

The implementation of the present invention will now be described with reference to the following examples.

Example Indium 2.0% by weight, Cadium cum 66.7% by weight,
Zinc 10.0% by weight, lead 0.05% by weight, thallium 0.
Smelting intermediate 100Kf (dry 11) containing 5wt 1%
K Add 20t of water and add 1+1 sulfuric acid to pH 5.
, stirred gently for 1 hour, left to stand for 4 hours, removed the supernatant, added 1+1 sulfuric acid to the residue until the pH of the aqueous solution reached 1.0, and washed with a filter press for 1 hour. 230 tons of an aqueous solution having the composition shown in Table 3 was obtained.

Table 3: To the above aqueous solution, 1.2 tons of Zn-Cd alloy powder obtained at a zinc distillation factory was added to the indium in the aqueous solution, and in a quiet device for 24 hours, the sponge-like indium was 2.1 to 4.
(dry) was obtained. Its quality is shown in Table 4.

Table 4 The crude indicum shown in Table 4 was dissolved by adding concentrated hydrochloric acid,
An indium plate having an In concentration of 180 t/l and a pH of 1 or less was prepared, and an indium plate having a surface area of 200 mm was added thereto, and the mixture was left for 24 hours with gentle stirring. The precipitated metal content was separated by 1, and the R liquid was adjusted to pH 1.0 by adding 50% by weight aqueous sodium hydroxide solution.After that, the same alloy powder used in the previous step was mixed with 1.0% of the indium content. After adding an amount of OW and stirring, the mixture was allowed to stand still for 24 hours to obtain O-phase indium having a composition of 1.9 as shown in Table 5.

Table 5 This sponge-like indium was thoroughly washed with water, further dehydrated using a hydraulic press, and then flaky sodium hydroxide was added to the indium at a ratio of 5 weights and 1% to the amount of indium, and the weight valves formed by heating and melting were removed. 1.8% crude indium was obtained. The quality of the tuna is shown in Table 6.

Table 6: Put the above crude indium into a crucible with an open top S.
The mixture was treated at normal pressure for 5 hours at t:' to evaporate and remove impurities. The quality of the distilled I/Zicum was as shown in Table 7.

Table 7 Next, this distilled indium was dissolved at 350C, 2% by weight of ammonium chloride was added thereto to generate dross, which was removed, and the same amount of ammonium chloride was added to dross. , 1.7k of purified indium with a purity of 99.99 or higher was obtained.

The yield of indium from the smelting intermediate was 85%.

Its composition is shown in Table 8.

Table 8 As is clear from the above examples, according to the method of the present invention, extremely pure indium can be recovered at a high yield.

Patent applicant: Sumitomo Metal Mining Co., Ltd. Agent: Patent attorney Yasuzo Kaizu Same: Patent attorney Hirayama - Sachi

Claims (1)

[Claims] In a method for recovering high-purity indium from an acidic sulfuric acid aqueous solution containing indium, an alkali is added to the aqueous solution to adjust the pH to 0.5 to 1.2, and zinc-cadmium is added in an amount of 1 to 1.3 times the indium in the aqueous solution. A first step in which alloy powder or zinc powder with good purity is added and cementation is performed to precipitate and separate crude indium, and the crude indium obtained in the first step is dissolved in a mineral acid aqueous solution and then dissolved in the aqueous solution. a second step in which an indium plate is added to perform cementation and the generated metal is separated to obtain an indium-containing aqueous solution, and an alkali is added to the aqueous solution obtained in the second step p) 10. 5 to 1.2, add 0.9 to 1.1 equivalents of zinc-cadmium alloy powder or zinc powder of good purity to the indium in the aqueous solution and perform cementation to form a precipitate containing indium. a third step of separating the nine precipitates obtained in the third step, a fourth step of melting the nine precipitates obtained in the above third step to obtain crude indium, and separating the nine precipitates to obtain crude indium; The fifth step is to heat indium to its i-t or 900 to 1051V, add ammonium chloride of 2% by weight or more, heat and melt it, separate the resulting dross, and recover high-purity indium. The above method, characterized in that it consists of.