JPS6114133A - Method for recovering gellium from dust produced by electrolyzing aluminum - Google Patents

Abstract

PURPOSE:To recover Ga from dust produced by electrolyzing Al in a high yield by adding a specified oxidizing agent to the dust, carrying out oxidation leaching, and extracting Ga from the resulting leaching soln. CONSTITUTION:An oxidizing agent such as KMnO4, MnO2, H2O2, O3 or KCrO4 is added to dust produced in an Al electrolyzing furnace, and oxidation leaching with a mineral acid is carried out. An org, solvent A such as phenol contg. a cation exchange type extracting reagent such as di-2-ethylhexylphosphoric acid (DEHPA) is added to the resulting leaching soln. to extracted preferentially Ga ions, and this extraction soln. is washed with hydrochloric acid alpha to separate ions of Fe, Al, V, etc. The Ga ions are back-extracted by adding hydrochloric acid beta having a lower condn. than the hydrochloric acid alpha to the extraction soln., and an org. solvent B such as kerosene contg. a neutral or basic extracting reagent such as isopropyl ether as an ion pair extraction type extracting reagent is added to extracted preferentially the Ga ions. The Ga ions are further back- extracted by adding a dil. aqueous mineral acid soln. to the extraction soln.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recovering gallium from electrolytically generated aluminum dust.

Gallium has recently attracted attention as a semiconductor material such as gallium-arsenide (GaAs) or gallium-phosphide (GaP).

Gallium is an element that exists widely on earth, but because it is not produced as a high-grade mineral, it has traditionally been recovered from Bayer liquid when producing alumina from bauxite or from the leaching residue of lead smelting.

However, in these methods, the content of gallium 4 in the raw material for gallium recovery is very low, so that recovery requires complicated steps and expensive processing costs.

For example, methods for recovering from Bayer's liquid include the lime method, the carbonation method, and the electrolytic method, of which the electrolytic method is industrially the most superior. This electrolyte #@ performs primary electrolysis of Bayer's solution using a mercury cathode and a nickel anode, treats the resulting crude gallium with caustic soda, and then subjects the solution to secondary electrolysis, but mercury is used. Therefore, there are problems regarding pollution.

By the way, as mentioned above, the Bayer liquid contains gallium, and this gallium exhibits the same behavior as aluminum in the Bayer process, and almost all of it moves into the alumina. And the gallium concentration in alumina varies depending on the WWI of the raw bauxite ore, but it is the number 1 (lp, ρ, 100p, l), #, I! If removed, it will be mixed into the aluminum metal during the electrolysis of alumina, but some of it will migrate into the dust generated during the electrolysis. This dust can be collected by various sinus dust devices including electrostatic precipitators, but if the gallium concentration in the dust is O, OSS.
It reaches 0.3% by weight, which is several tens of times more concentrated than the concentration in the alumina. The general composition of some aluminum electrolytically generated dust is:
Ga O, O3, KCrO8~o, 3o weight x SFe
O, 5-2.0% by weight, Af 10-2020% by weight, Na 10-20% by weight: A1F15-30% by weight
, C10-30 10-30% by weight of Si, Ni, Ti
, Ca, Cu.

Each of Nf, Co, etc. is contained in an amount of 1% by weight or less, and the remainder is water.

A method for recovering gallium from this aluminum electrolytically generated dust is disclosed in British Patent No. 1,527,981. This method involves adding an excess of alkaline flux to a dust containing up to 0.62% gallium, and then S.O.
This method produces metallic gallium by adding metal powder such as aluminum or magnesium to dissolved gallium that is leached by roasting and immersion at 0°C and fixing it. However, this method does not require the use of an expensive alkaline flux. Since it is necessary to add several times the amount of dust and roast it, the cost increases accordingly and is not practical.

The present invention aims to solve the above-mentioned problems and provide a method for recovering gallium with high yield. By adding the agent, it is possible to significantly and selectively improve the gallium leaching rate without performing high-temperature operations such as roasting the dust before leaching. aluminum ions and iron ions contained in high concentrations, and even at low concentrations, vanadium ions that are harmful to subsequent processes (such as aqueous electrolysis). It is a place where Ga can be effectively and easily separated and purified at a low concentration and recovered and concentrated with high yield.More specifically, when dust generated in an aluminum electrolytic furnace is treated with mineral acid,
Mn0g, MnO, H2O1, O3, KCrO,
Crag and other oxidizing agents are added to sl to perform oxidative leaching treatment, Ga ions are preferentially extracted from the leachate with organic solvent A containing a cation exchange extractant, and the back extract is extracted with aqueous hydrochloric acid solution A. After washing and separating each ion such as Fa, ^L, and V, Ga ions are back-extracted from the extract with a hydrochloric acid aqueous solution β having a lower concentration than the above α, and from the back-extract, Ga ions are extracted using an ion pair extraction type extractant. G8 ions are preferentially extracted with an organic solvent B containing a neutral extractant or a basic extractant, and the Ga ion-concentrated extract is extracted with a dilute mineral acid aqueous solution.
This is a method for recovering gallium from aluminum electrolytically generated dust, which is characterized by back extraction of ions, and in some cases, a hydrochloric acid aqueous solution lol! The order in which Ra and the aqueous hydrochloric acid solution β are used may be changed.

Here, the alkaline flux employed in the above method is Na.

These include CO2, NaOH, -COa, and OH.

Next, organic solvents A and B will be described.

The organic solvent A is composed of an extractant and a diluent, and the following cation exchange type extractant is preferably used as the extractant.

(a) Acidic organic phosphorus compounds, especially acidic phosphoric esters having 8 to 20 carbon atoms, such as 2-ethylhexyl phosphate mono-2-ethylhexyl ester or di-2-ethylhexyl phosphoric acid (DEHP^).

(b) Carboxylic acids, especially those having 6 to 20 carbon atoms, such as naphthenic acid represented by the formula or carboxylic acid represented by the formula.

(c) As a diluent for sulfonic acid, especially alkylbenzenesulfonic acid or dialkylnaphthalene sulfone group, or organic solvent A, any diluent may be used as long as it dissolves the extractant and is insoluble or very sparingly soluble in water. Examples include paraffin-threaded aromatic solvents, naphthenic solvents, halogenated hydrocarbon solvents, higher alcohols, phenols, ketones, and the like.

The organic solvent B also consists of an extractant and a diluent, and the extractant is a neutral extractant of ion pair extraction type, such as isopropyl ether, tributyl phosphatide, etc.
(TBP), methyl isobutyl ketone (AIBK),
Trioctylphosphine oxide (TOPO) or basic extractants such as primary, secondary and tertiary amines, and quaternary ammonium salts are used.

As the dilution for organic solvent B, the organic solvent A described above is used.
An appropriate diluent is selected and used.

The operating procedure of the present invention will be explained below along with a flowchart, and will be described in detail with reference to Examples and Comparative Examples.

<Example 1> Gallium content 0.13 weight 1X (^L22.2 weight
F-type, 8wt% SFe 0.72wt full t=
Dust collected by the electric collector installed in the +7-mu electrolytic cell
''-'''0°00a7zlC1''1pa2°G (purity 9
8x) was added and leaching was carried out at 95°C for 2 hours.

After filtering the leachate, analysis of the filtrate revealed that 78 s of gallium originally contained in the dust had been dissolved in the liquid. The composition of the leachate at this time is shown in Table 1 below.

Table 1 (Unit: gll) (Comparative Example 1) When the same dust as in Example 1 was used, KMnO4 was not added, and all other conditions were the same, the Ga leaching rate was 54. The composition of the leachate at this time is shown in Table 2 below.

Table 2 (Unit Q/1) LpHGa Aj! Fs V F Next, the oxidized leachate of dust will be explained using a flowchart of the extraction operation.

30voj di-2-ethylhexyl phosphate (DEHP
The organic solvent A, which is the kerosene solution in step ^), and the dust sulfuric acid leachate were reacted in operation 1 at a ratio of 0/^ = 171.

In step 2, react with a washing solution of 7v+oll/l aqueous hydrochloric acid solution at 0/^=271 to remove Fe, ^1, and V by washing with an organic solvent, and in step 3, use a back-extracted solution of 2IIot/i aqueous hydrochloric acid solution. , 0/^=10/1 to back-extract Ga.

In step 4, concentrated hydrochloric acid was added to obtain a 4-chain Oa/no hydrochloric acid aqueous solution. In Operation 5, 20voJLX ) Liptylphosphiny ) (TOP) is reacted with organic solvent B, which is a kerosene solution, at a ratio of 0/^ = 1/4, and in Operation 6, 0.1mo7/
Ga from organic solvent B with JL hydrochloric acid aqueous solution at 0/^=3/1
I did a back extraction.

The results are shown in Table 3.

Table 3 (Unit glI!> *The overall yield of Ga was 74%.

<Example 2> Gallium content 0.20 weight 7g (A719.8 weight
lX 5F 23.9% by weight, Fe 1.1% by weight 2)
The dust 1509 collected in an electrostatic precipitator attached to an aluminum electrolytic tank was reduced to a slurry concentration of 300 seconds, and then HaS 0z1909 and Mn02159 (purity 90x) were added and leached at 95°C for 2 hours. .

After filtering the leachate, the filtrate was analyzed, and it was found that 78X of gallium, which was originally contained in the dust, had been dissolved in the liquid. The composition of the leachate at this time is shown in Table 4 below.

Table 4 (Unit a/I!> (Comparative Example 2) When using the same dust as in Example 2 above, without adding MnO, and keeping other conditions the same, the Ga leaching rate was 41
It was X. The composition of the leachate at this time is shown in Table 5 below.

Table 5 (Unit: 91) Table 6 shows the results obtained using the same method as in Example 1.

Table 6 (Unit: g/l~) *As a result, the overall yield of Ga was 57.

[Brief explanation of the drawing]

The figure is a flowchart showing the operating procedure of the present invention.

Claims (1)

[Claims] 1. When treating dust generated in an aluminum electrolytic furnace with mineral acid, KMnO_4, MnO_2, H_2O_2
, O_3, KCrO_4 and other oxidizing agents are added to carry out oxidative leaching treatment, Ga ions are preferentially extracted from the leachate with organic solvent A containing a cation exchange type extractant, and the extract is extracted with aqueous hydrochloric acid solution A. After washing and separating each ion such as Fe, Al, and V, Ga ions are back-extracted from the extract with a hydrochloric acid aqueous solution β having a lower concentration than α above, and from the back-extract, Ga ions are extracted using an ion-pair extraction type extractant. Aluminum characterized by preferentially extracting Ga ions with an organic solvent B containing a basic extractant or a basic extractant, and then back-extracting the Ga ions from the concentrated extract with a dilute mineral acid aqueous solution. A method for recovering gallium from electrolytically generated dust. 2. When treating dust generated in an aluminum electrolytic furnace with mineral acid, KM_nO_4, MnO_2, H_2O_
2. Oxidative leaching treatment is performed by adding O_3, KCrO_4 and other oxidizing agents, and Ga ions are preferentially extracted from the leachate with organic solvent A containing a cation exchange type extractant.
After preferentially back-extracting Ga ions from the extract using an aqueous hydrochloric acid solution β, the same extract was washed with an aqueous hydrochloric acid solution a having a higher concentration than the above β to separate Fe, Al, V, and other ions. Ga ions are preferentially extracted from the back extraction solution β containing Ga using an organic solvent B containing a neutral extractant or a basic extractant, which is an ion pair extraction type extractant, and the Ga ions are extracted from the concentrated extract. A method for recovering gallium from aluminum electrolytically generated dust, which comprises back-extracting Ga ions with a dilute mineral acid aqueous solution.