JP2720918B2 - How to recover indium from zinc alloy - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for preferentially extracting indium from a zinc alloy containing Pb, Sn, Fe, Cu, etc. as impurities in addition to indium. is there.

(Prior Art) Demand for indium as a liquid crystal material and a III-V compound semiconductor material is expected to increase in the future. However, there is no so-called indium ore, and a small amount of indium is present in zinc ore and is recovered from zinc smelting intermediate products. Therefore, an efficient recovery method is required.

Zinc smelting intermediates as indium raw materials vary widely depending on the zinc smelting method, and include residues in zinc smelting, for example, distillation residues in dry refining and residues in hydrometallurgy.

JP-A-55-11149 proposes a method of distributing and recovering indium in molten lead by bringing molten zinc containing indium into contact with molten lead. In this method, in order to further recover indium from molten lead containing indium, indium is oxidized by a method such as blowing air into the molten lead, and is recovered as dross. However, this method is not suitable for extracting indium from a zinc alloy having a low indium concentration because the ratio of indium in molten zinc / molten lead is at most about 1 / 1.5. In addition, when an acid dissolution method is studied as a method for recovering indium from an indium-containing lead alloy, the dissolution rate of the alloy is low, so that there is a disadvantage that the cost is high and the productivity is low.

Next, JP-A-56-146834 (JP-B-61-36055)
Is to volatilize and remove zinc from indium, iron, lead, arsenic, iron dross containing zinc, etc., and then cool it by In, Ag, Sn
We propose a method of separating a non-magnetic lead liquid phase containing iron and a magnetic solid phase containing Fe and As, and recovering indium, silver, tin and the like as valuable metals. This method requires a post-treatment of removing silver, tin, and the like in order to selectively recover only indium because silver and tin in addition to indium are mixed in soda scum in a large amount. That is, after indium and tin are collected in soda scum by soda treatment of a non-magnetic substance, they are leached as an acidic solution containing In, and indium is recovered by a known method. Therefore, this method has a disadvantage that the number of processing steps is increased when selectively recovering indium.

(Problems to be Solved by the Invention) Japanese Patent Application Laid-Open No. 55-111449, which is a conventional method for preferential extraction of indium from a zinc melt containing impurities, is a method for recovering indium in molten lead. Although it is suitable for oxidizing and removing the indium, when considering dissolving the indium-containing lead alloy in an acid or the like and recovering the indium by a known wet treatment method, it is generally difficult to recover the indium because the dissolution rate is low. That is, when the indium content in the lead alloy is extremely high, the indium can be recovered economically even if the dissolution rate in the acid is low, but is generally not economically viable.

Therefore, the present invention eliminates the disadvantages of the above-mentioned known art,
It is an object of the present invention to provide a method capable of extracting indium preferentially from a zinc melt containing indium and other impurities, and subjecting the indium extracted substance to a known indium recovery treatment.

(Means for Solving the Problems) As a basic experiment, the present inventors conducted an extraction test using a Zn-1% In alloy produced by adding In metal to JIS pure zinc.

 The experimental method was as follows.

150 g of a Zn-In alloy (In 0.99%) was sealed in a quartz tube together with 15 g of zinc chloride, kept at 500 ° C. for 4 hours, and quenched with a sufficient amount of water.

The quartz tube was broken, and zinc chloride was taken out and weighed. Since zinc chloride is hygroscopic, zinc chloride was rapidly dissolved in water and the weight of the solution changed. Therefore, the amount of zinc chloride was determined from the change in weight.

Since undissolved zinc chloride, indium hydroxide, and the like remain in the aqueous chloride solution, the undissolved material was completely dissolved using a nitrate mixed acid.

When the In grade in the chloride was calculated from the volume and In concentration of this solution and the chloride weight obtained earlier, the In grade in the chloride after the treatment was 3.3%, and in the Zn-In alloy after the treatment. I
The n grade was found to be 0.70%.

This result shows that In was extracted from the alloy phase into the chloride melt. In addition, it can be seen that the In grade of the Zn—In composite chloride melt is about five times that of the equilibrium Zn—In alloy.

Thereafter, the above method was carried out on an intermediate product of zinc smelting (containing impurities other than indium to be recovered), thereby completing the present invention.

That is, the method of the present invention is a method for recovering indium from a zinc alloy, comprising: bringing a zinc chloride melt into contact with a zinc alloy containing indium; and extracting indium in the zinc alloy into a chloride melt. It is.

 Hereinafter, the configuration of the present invention will be described in detail.

The starting material in the method of the present invention is a zinc alloy containing Cu, Ag, Fe, Sn, Pb and the like as impurities in addition to indium to be recovered. For example, in dry smelting of zinc, sinter containing zinc oxide as a main component is reduced to obtain distilled zinc. When this distilled zinc is treated, for example, in a New Jersey rectification column, the iron dross obtained as an intermediate product is a starting material for the process of the present invention. Iron dross is generally about 80-90
% Zinc, about 5-15% lead, about 0.5-1.5% indium, about 0.5-2.0% iron, about 0.2-0.6% arsenic, about 0.05-
It contains 0.7% silver and about 0.2-2.0% tin.

In addition, distilled zinc contains several hundred ppm of indium, and such distilled zinc is also treated by the method of the present invention.

Furthermore, smoke ash, anode slime and the like generated in the smelting process of zinc and lead also contain a small amount of indium, and these smoke ash and the like are melted and recovered as indium by the method of the present invention.

Similarly, among the residues generated in the dry smelting of zinc, the non-magnetic material subjected to magnetic separation contains about 0.01 to 0.04% of indium and contains Ag, Fe, Zn and the like as impurities. Such non-magnetic residues are also treated by the method of the present invention.

In addition, sludge generated by galvanization can be treated.

Although the indium content of the zinc alloy industrially generated as a by-product as described above is at most several percent, the method of the present invention can also treat an alloy containing a higher concentration of indium if necessary.

The treatment method in the present invention, for example, by heating and melting a zinc alloy containing indium among zinc smelting intermediate products, by bringing the zinc chloride melt into contact with the zinc alloy melt, the In in the alloy into the chloride It is extracted and recovered as a Zn-In complex chloride melt. The indium is recovered in this way because there is a significant difference in the distribution of indium between the molten zinc alloy and zinc chloride, and indium is highly concentrated in the molten zinc chloride.

When zinc chloride is used because the extraction target is a zinc alloy, an intermetallic compound that prevents extraction is not formed by the reaction between the salt and the alloy, and the extraction operation can be performed. Zinc chloride has an affinity between sodium chloride and ferric chloride. If the affinity is large like sodium chloride, indium will not concentrate in sodium chloride. On the other hand, when trying to recover indium from a zinc alloy using a salt having a small affinity such as ferric chloride, copper having a small difference in affinity with ferric chloride and having a smaller affinity than ferric chloride, Chloride such as silver may also be concentrated in ferric chloride. Therefore, indium can be preferentially extracted using zinc chloride which does not have such a defect.

Since the molten zinc chloride has a lower specific gravity than the molten zinc alloy, it exists floating above the molten zinc alloy layer, and the extraction temperature may be at least the melting point of zinc chloride and the zinc alloy. The extraction time depends on the amount of the zinc alloy and the like. In the method of the present invention, indium is extracted through the contact interface between the two. It is preferable to mix both for effective extraction, but usually stirring for 1 to 2 hours is sufficient.

The amount ratio of zinc alloy and zinc chloride is increased as the ratio of zinc chloride is increased, but the amount of indium recovered is increased, but the amount of liquid in wet post-treatment is increased. It is necessary to decide.

In order to recover indium from zinc chloride from which indium has been extracted as described above, a method of dissolving solidified zinc chloride in water or an acid and substituting and depositing indium with aluminum or the like, a solvent extraction method (JP-A-60-251128) And known methods such as a method such as (A) and a chelating exchange resin method.

The zinc content in the zinc chloride for extraction is recovered as zinc hydroxide which can be used as a raw material for zinc smelting after treating the acid solution.

(Function) The present invention is characterized in that, as in the prior art, indium is extracted once in a state where it can be directly dissolved in an acid or the like without being transferred to a metal such as lead.

For this purpose, indium is concentrated in the molten zinc chloride using molten zinc chloride as an extractant. As a technique of using chloride for recovery of indium, Japanese Patent Application Laid-Open No. 57-9842
(No. 61-17888). In this method, chloride is added together with a reducing agent to zinc ore containing indium, dry or hydro-smelting residue, etc., and heated to 800 ° C or higher to convert In to chloride.
Chloride such as calcium chloride and ammonium chloride is used as a chloride volatile agent because it is a method of volatilizing and recovering. In addition, Sn, Ag, Cu and the like are also mixed in the recovered chloride.
That is, it is not used as a selective enrichment agent for indium as in the present invention.

Similarly, JP-A-56-9340 discloses a method for recovering indium using chloride. This method is a method of oxidizing and roasting zinc sulfide ore, smoke ash, anode slime, and the like in the presence of a reducing agent to volatilize indium. The present invention is a method in which the roasted ore or the like can be treated, but chloride is used not as a volatilizing agent but as a condensing agent.

 Hereinafter, the present invention will be described in detail with reference to examples.

(Examples) Examples Generated in the rectification step of distilled zinc in a new jersey system.
Elution of Pb from run-off metal (residual zinc residue) (Liqu
ation), a zinc-iron alloy containing In (hereinafter referred to as iron dross) generated during the treatment was treated. Iron dross usually has a Zn grade of 80-85%, and has a high Pb grade because it contains a lead phase as a separate phase.

The composition of the iron dross subjected to this treatment was as follows.

15 kg of iron dross was heated and melted at 520 ° C in a # 30 graphite crucible. As soon as 3 kg of zinc chloride was added to the molten iron dross, the zinc chloride dissolved.

The melt was heated to 560 ° C. and then stirred for 90 minutes. Thereafter, an analytical sample was sampled from iron dross and zinc chloride. After the analytical sample is weighed, it is dissolved with a nitrate mixed acid, and the chlorine content and the iron dross quality after treatment obtained from the amount of the solution, each element concentration and the chloride weight are as shown in the table below.

The above results show that In can be selectively extracted from iron dross.

Immerse the Zn plate in a solution in which zinc chloride after treatment is dissolved in acid,
The indium was recovered by displacement. Indium recovery from zinc chloride was 90-95%.

Comparative Example 1 The same stirring treatment as in Example 1 was performed at 850 ° C. using sodium chloride in place of zinc chloride used in Example 1, and the indium content in sodium chloride was analyzed. It is considered that this was contaminated by a small amount of metal mixed into the chloride, but in any case, it was found that indium was not extracted into the chloride.

Comparative Example 2 Ferric chloride was used in place of zinc chloride used in Example 1, and the same stirring treatment was performed at 550 ° C. as in Example 1. As a result, chloride and iron dross solidified in a short time. The stirring was stopped because the indium could no longer be extracted.

(Effect of the Invention) This method is an excellent method for recycling indium because indium can be preferentially extracted even when impurities such as Cu, Ag, Fe, Sn, and Pb are contained.

In addition, the industrial zinc chloride used as a concentrating agent in the present invention is 200 to 250 yen / kg, and its zinc content can be recovered as a zinc smelting raw material, so that it is practical in terms of cost.

Furthermore, in the zinc dry smelting method, a small amount of indium is contained in distilled zinc, and is concentrated in the rectification step. According to this method, In concentrated in the zinc melt together with other impurities (Pb, Sn, Fe, Cu, etc.) can be selectively recovered in a form that can be directly dissolved in an acid. Thus, indium can be recovered from a zinc alloy containing a small amount of indium.

Claims (1)

(57) [Claims] 1. A method for recovering indium from a zinc alloy, comprising bringing a zinc chloride melt into contact with a zinc alloy containing indium and extracting indium in the zinc alloy into a chloride melt.