SU716306A1 - Method for purifying zinc solutions from cadmium by sorption - Google Patents

Abstract

A METHOD FOR CLEANING ZINC SOLUTIONS OF SURPTION Cadmium on anibnite, characterized in that, in order to increase the selectivity of the process and reduce the consumption of reagents, sorption is carried out on the ionite in the form of dialkyldithiophosphate.

Description

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ABOUT)

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The text refers to the field of hydrometallurgy of non-ferrous metals, mainly to the purification of zinc solutions, and can be used to deeply clean sulphate zinc solutions from cadmium, copper and other impurities, as well as to remove cadmium from zinc solutions. A known method of cleaning zinc solutions from cadmium by sorption on an; Onite C i 3.: - -;

According to this method, 0.5-2 g-ion / l CS is added to the solution in advance to bind cadmium to ibn ddfcgj, which is extracted by passing through an anohybene 10 cmL. . From anionitkadmi washed with a solution of NaCB with the addition of

The main disadvantage of the cadmium sorption method on anion exchangers is the need to introduce large amounts of ce ions into an aqueous solution, which are a harmful impurity during the electrolysis of zinc sulphate solutions and in the presence of chemical agents: special purification is required. In addition, the separation of cadmium and zinc is not sufficiently effective; a large consumption of reagents is required for carrying out the process.

The aim of the invention is to increase the selectivity of the process and reduce the consumption of reagents. The goal is achieved by the fact that the sorption is carried out on the anion exchange resin in the form. dialkyldithiophosphate. Strong, osnvNye anion, e.g., containing in its composition, quaternary ammonium, pyridinium or sulfonievao group - converted into a form dialkyl, e.g., di- or dibutilditiofosfata 2-etilgeksilditiofosfata by treating a resin containing a mineral acid anion, dialkyl dithiophosphoric acid with a solution of water and 6 an organic polar solvent (for example, in an aqueous ethanol solution). The degree of conversion of the anion exchanger into the dialkyDithiophosphate form is increased by adding an alkali solution to the reaction mixture and using porous anion exchangers. After processing, the resin is washed with ethanol and then with water.

When anion exchanger in a dialkyl dithiophosphate form is contacted with a zinc solution containing cadmium, the formation of a strong cadmium dialkyldithiophosphate complex, which is formed in the resin phase, and the practical polymer dissolves in the water solution due to its hydrophobicity. .

the functional group of the anion exchanger transforms into the form of the anion present in the aqueous solution. Nap limer, upon cadmium sorption from

sulfate solution with anion exchange resin containing a quaternary ammonium group in the form of dialkyl dithiophosphate, the reaction occurs:

reaction occurs:

(Cd2). {Sof) - (),

(cd

where ft is dialkyldithiophosphate ion, the indices b and c denote the aqueous phase and the resin phase, respectively. Since dialkyldithiophosphate ion with cadmium cation is a much more durable complex than with zinc cation, cadmium is extracted selectively from aqueous zinc solution,

Zinc almost completely remains in the YdBa phase. At the same time, the concentration of sulfate ion in the aqueous solution created by zinc sulfate contributes to obtaining high coefficients.

cadmium distribution. In contrast to the known method by which

cadmium is extracted in anionic form, for example, CdCPI, by the proposed method, in which

cadmium is absorbed in the form of a cation.

There is no need to add C ions to the solution.

Cadmium desorption can be carried out with water. In this case, due to the low concentration of b-ion in

orgfase, distribution coefficients

cadmium are small. Thus, it is possible to purify ZINC61X sulphate solutions from cadmium without the consumption of inorganic reagents. Desorbtsi cadmium,

5 In addition, it is possible with a solution of ammonia aka — moreover, more concentrated solutions containing ammonium cadmium complexes are obtained. After desorption, the anion exchanger in the dialkyldithio0 phosphate form is sent to the cadmium sorption stage without additional operations.

During cadmium sorption from zinc sulphate solutions using sil

5 noon anion exchangers in the dialkidithiophosphate form simultaneously extract a number of harmful cationic impurities (copper, lead, antimony, mice, etc.) and anionic character (chloride, fluoride, nitrate ions), which must be introduced before the solution is fed to electrolysis.

PRI me R 1. Conducted cleaning from impurities zinc sulfate solution containing 65 g / l Zn,

1.6 mg / l Cu, 6.4 mg / l Cd, 2.9 g / l

SS, AB-17 anion exchange resin (containing

quaternary ammonium groups) in

diisobutyldithiophosphate. The ratio of T: W 1:10. Found in aqueous solution after sorption: Cd 0.1 MG / L} C was not detected; NE 2.5 g / l. The degree of purification from impurities was,%: from copper 100%

45 from cadmium 98%, from ionic ion 14%.

Example2. In the conditions analogous to example 1, sorption of impurities was carried out using anion exchanger AB-17 in the form of di-2-ethylhexyldithiophosphate. (56 found in an aqueous solution after sorption: Cd 0.1 mg / l; Cu is not common; CB 2.0 g / l. The degree of purification from impurities was,%: from copper 100%, from 98% cadmium, from ions 31%.

The proposed method makes it possible to extract cadmium from zinc solutions q with a high selectivity; zinc is almost not sorbed by the anion exchanger in the dialkyl dithiophosphate form. Under certain conditions, cadmium is collected by more than 98% even under static conditions. The method makes it possible to reduce the consumption of reagents (in principle 5, the process of desorption by cadmium can be non-reagent). For effective cadmium sorption, the addition of ions to an aqueous solution is not required. When cleaning zinc

Cadmium sulfate electrolytes: extraction of other harmful impurities, such as copper, arsenic, chlorine, fluorine, etc., is reached at a time.

H

Claims (1)

METHOD FOR CLEANING ZINC SOLUTIONS FROM CADMIUM BY SORPTION on anion exchange resin, characterized in that, in order to increase the selectivity of the process and reduce the consumption of reagents, the anion exchange resin is in the form of dialkyldithiophosphate. .... SU „,. 716306 I ..-..-..-. '' ^to '' _71b306