RU1819856C - Method of silver extraction from industrial, gelatin-containing sewage - Google Patents

Description

0 dose of lignosulfonate 0.11 kg per 1 m of waste

3,5. then

sodium in quantity

water, mix for 15 minutes and stand in

within 1 h. Clarified water contains 2.2

mg / l of silver.

PRI me R 2. In example 1, sulfuric acid is introduced to a pH of 4.0, and sodium lignosulfonate in an amount of 0.09 kg per 1 m of wastewater. Silver content in clarified

water is 3.9 mg / l,

PRI me R 3. In example 1, sulfuric acid is introduced to a pH of 4.5, and sodium lignosulfonate in an amount of 0.12 kg per 1 m of wastewater. The clarified water contains 1.7 mg / l of silver.

L rimer 4 (comparative). In Example 1, sulfuric acid was introduced to a pH of 3.9, and sodium lignosulfonate in an amount of 0.13 kg per 1 m of waste water. The silver content of clarified water is 2.0 mg / L.

PRI me R 5 (comparative), In example 1, sulfuric acid was introduced to a pH of 4.0, and sodium lignosulfonate in an amount of 0.08 kg per 1 m of waste water. The silver content of clarified water is 12.4 mg / l.

Example b (comparative), In example 1, sulfuric acid was added to pH 5.0, and sodium lignosulfonate in an amount of 0.09 kg per 1 m of wastewater. The silver content of clarified water is 31.1 mg / L.

Example p 7 (comparative). In Example 1, sulfuric acid is added to a pH of 3.0. The clarified water contains 4.8 mg / l of silver.

Example 3 (prototype). Concentrated sulfuric acid is added to wastewater with a silver content of 900 mg / L and a pH of 6.85 to a pH of 2.3. Then it is boiled in a decanter for 2 hours until completely clarified, neutralized with a pH of 7.0 and then boiled still in

for 30 minutes, after which the heating is turned off and cooled at a speed of 0.15 ° C / min. The clarified water contains 4.0 mg / l of silver.

The results of experiments on the extraction of silver from wastewater are given in the table,

The table shows that the dose reduction

sodium lignosulfonate below 0.09 kg / m3

(experiment 5) leads to poor recovery

silver. A similar effect is observed.

in cases where the treatment of LST water

lead at a pH below 3.5 units and above 4.5

units (experiments 6.7). LBT dose increase higher

0.12 kg / m3 (experiment 4) is impractical since

does not lead to a significant increase

silver extracts.

Thus, the process of extracting silver from wastewater should be carried out by treating the effluents with sodium lignosulfonate in an amount of 0.09 - 0.12 kg per 1 m3 of wastewater at a pH of 3.5 - 4.5.

The application of the proposed method allows: to reduce by 4 to 5 times the processing and coagulation of silver-containing sludge; exclude from the process the boiling stages of wastewater; reduce energy costs; reduce the consumption of sulfuric acid by 5-6 times.

Claims (1)

SUMMARY OF THE INVENTION A method for recovering silver from industrial gelatin-containing wastewater, comprising treating them with sulfuric acid and precipitating, characterized in that In order to reduce the time of the process, the number of operations, reduce the energy consumption and consumption of sulfuric acid, the wastewater is additionally treated with sodium lignosulfonate in an amount of 0.09 - 0.12 kg per 1 m3 of wastewater at pH 3.5 - 4.5.