SU1576487A1 - Method of depositing silver halogenide from gelatin-containing solutions - Google Patents

Abstract

The invention relates to methods for the recovery of silver from aqueous solutions and can be used in the processing of gelatin-containing water from the film industry. The purpose of the invention is to increase the degree of recovery of silver from solution and reduce the process time. The silver-gelatin-containing solution is treated with coagulant containing AL 2 (SO 4) 3 and dispersant NP in the ratio (15-25): 1 at the rate of 150-400 mg of coagulant per 1 liter of solution. Alkali is then added to the solution to a pH of 6.5-7.5 and silver sludge is settled. The residual silver content in the solution does not exceed 0.86 mg / l, and the rate of settling is 1.22-1.56 mm / s. 1 tab.

Description

The invention relates to methods for extracting silver from aqueous solutions and can be used in the processing of gelatin-containing waters of film production.

The purpose of the invention is to increase the degree of extraction of silver from solutions and reduce the process time.

Example 1. Wastewater containing 315.1 mg / l of silver and 750 mg / l of gelatin is treated for 5 minutes with a coagulant with the ratio Ale (S04) 3 disodium methylene bis (naphthalene sulfonate) (NF) 19: 1, in the amount of 150 mg per 1 liter of solution. Then the solution is neutralized with alkali to a pH of 7.3, stirred for 2-5 minutes and settled for 30 minutes. The residual silver content in the solution

0.86 mg / l; rate of settling 1.22 mm / s.

Examples 2-7 .. Wastewater treatment is carried out analogously to example 1.

The processing conditions and the residual silver content are given in the table,

As can be seen from the table, with a ratio of A. (504) h: NP in a coagulant that is different from (15-25):, as well as when the consumption of coagulant is less than 150 mg / l and pH is less than 6.5, the residual silver content increases solution. This also increases the coagulation time.

 Increased coagulant consumption. (above 400 mg / l) and pH (above 7.5) is impractical because it is not a weight

05 Ј 00 S1

31

It is possible to increase the degree of silver recovery or reduce the process time, but it requires additional consumption of reagents.

Thus, the invention allows to halve the duration of the deposition process and increase the degree of silver recovery from solution.

Claims (1)

Invention Formula A method for precipitating a silver halide from gelatin-containing solutions, 764874 including treatment of the solution with coagulant, alkali and subsequent sedimentation of silver-containing sludge, characterized in that, in order to increase the recovery rate silver and reduce the process time, as a coagulant using "About fS euggsLg mixture of aluminum sulphate with disperser NF - disodium methylenebis (naphthalenesulfonate) with a mass ratio of A12 (B04) 3: NF equal to (15-25): lead to a pH of 6.5-7.5.