CS232937B1 - A method of reducing the salinity of acidic solutions repeatedly used after acidification by the addition of sulfuric acid to hydrochemical uranium mining - Google Patents

Abstract

The purpose of the invention is to reduce the salinity of acidic solutions repeatedly used after acidification by adding sulfuric acid for hydrochemical uranium mining and containing aluminum salts. The stated purpose is achieved by increasing the sulfate ion content in a part of the solution intended for leaching by adding concentrated sulfuric acid to a value of 100 kg.m"3 to 500 kg.m"3, by adding ammonium salts the ammonium ion content is adjusted stoichiometrically with respect to the aluminum content and by cooling the solution to a temperature of 20 °C to -10 °C crystals of aluminum ammonium alum Al2(NH4)2(SO4)4.24 H20 are precipitated, which are separated from the reaction mixture as a by-product. The acidic mother liquor is used to acidify the remaining part of the solution intended for uranium leaching. The invention can be used wherever metals are obtained by leaching sulfuric acid solutions, with aluminum and ammonium ions accumulating in these solutions.

Description

The invention relates to methods for reducing the solubility of acidic solutions repeatedly used after acidification by adding sulfuric acid to hydrochemical uranium mining and containing aluminum salts.

Up to now, in the hydrochemical extraction of uranium by means of circulating acidic solutions, after the uranium separation, the treatment of these solutions is carried out before they are re-injected until underestimated by the addition of concentrated sulfuric acid. The leaching results in the dissolution of the aluminum contained in the ore, which, together with the ammonium ions resulting from the surface treatment of the leaches, creates conditions in the sulphate leaching solution for the elimination of the sparingly soluble sulphate - alum ammonium alum, which causes considerable technological problems. Separation of aluminum from leaching solutions is solved by MS. No. 208,897 by sorption of aluminum on the cation exchanger and subsequent elution, which is a technologically demanding operation.

These disadvantages are substantially reduced by the method of reducing the salinity of acidic solutions repeatedly used after acidification by the addition of sulfuric acid to the hydrochemical extraction of uranium and containing aluminum salts according to the invention, which consists in separating from leaching solution a portion corresponding to 1-40% of the total volume. in which the content of sulphate ions is increased by the addition of concentrated sulfuric acid to a value of 100 kg.a ^- ^ to 500 kg.m-3, by addition of ammonium salts, preferably in the form of a solution after separation of ammonium dlurenate. the stoichiometric ratio with respect to the aluminum content and after cooling the solution to a temperature of from 20 ° C to -10 ° C and the precipitated crystals of low soluble aluminum ammonium alum are separated from the reaction mixture and the acidic mother solution is used to acidify the remaining part the total volume of the solution to be mixed measurement.

The proposed method separates the contaminated amounts of aluminum from the solution and limits it from the supply of ammonium ions to the leach solution circuit, thereby reducing the risk of precipitation of aluminum oxide in the deposit. Separated ammonium alum can be used for the preparation of aluminum and ammonium compounds.

The invention can be used wherever metals are obtained by the hydrochaalting process by leaching with sulfuric acid solutions, in which aluminum and ammonium ions accumulate in these solutions.

Example 1 a

From 10 m ^{J of} uranium sorption acid waste containing 5 kg.a ^{J of} aluminum and aa separated 1 m m, to which ae added 250 kg of concentrated sulfuric acid and 16 kg of solution after separation of ammonium dlurenate, thereby adjusting the ammonium ion content to quantity relative to aluminum. By cooling the resulting solution to 5 ° C, crystals of aluminum nitrate in a quantity of 50 kg are separated, which are separated by filtration. The filtrate ae is used to acidify the remaining 9 ml of uranium sorption waste and the solution thus obtained is again used to leach uranium.

Example 2

Of the 10 m ^ acid waste after sorption of uranium containing 7 kg.m ^ aluminum is separated with a 4 bp, i.e. 40% of the original volume and adjusted therein by adding concentrated sulfuric acid, the content of sulfate ions to a value of 200 kgm ^- ^. The ammonium ion content was adjusted to 4.9 kg / m @ 2 by addition of 20% aqueous solution to the sulfur sulfides and cooling of the resulting solution at 0 DEG C. resulted in the formation of 365 kg of aluminum ammonium alum crystals, which were separated from the reaction mixture. The solution remaining after separation of the crystals is mixed with 6 ml of the original sorption feed and reused for leaching the uranium.

Claims (1)

A method for reducing the salinity of acidic solutions reused after acidification by the addition of sulfuric acid to hydro-silent extraction of uranium and containing aluminum salts, A portion corresponding to 1 to 40% of the total volume is separated from the leaching solution in which ae increases the sulphate ion content by not more than 100 kg.m3 to 500 kg.m < after separation - diuranétu ammonium content of ammonium ions adjusted to half to twice the stoichiometric ratio with respect to the aluminum content, and after cooling the solution to a temperature from 20 ° C to -10 ° C, the crystals had a soluble alum hlinltoamonného «A1 ₂ (NH _{4) 2} ( SO _{4) 4} .24 H ₂ 0 separated from the reaction mixture and the mother acidic solution is used for dokyselení remaining portion of the total volume of the solution to leaching.