Method for comprehensive recovery of silver-containing lead slag

Patent metadata

Field	Value
Publication number	US-2019032170-A1
Application number	US-201716073805-A
Country	US
Kind code	A1
Filing date	Nov 21, 2017
Priority date	Nov 5, 2016
Publication date	Jan 31, 2019
Grant date	—

Abstract

The main steps are as follows: purification, de-leading, recovery and filtration, dissolving lead, hot filtration, cooling filtration, washing and hot decomposition, silver is recycled as silver powder, lead was recovered in the form of red lead, yellow lead and chlorinated lead respectively. Compared to existing technologies, the invention adopts a wet process, the amount of waste gas and dust produced in the process of fire treatment is reduced; silver powder, red (yellow) lead and chloride lead were obtained, it can be sold as final product with high value-added features. The tail liquid produced by the process returns to the corresponding process respectively, and the tailless liquid is discharged. The pyrolysis flue gas returns to the lead removal process, flue gas treatment process is reduced, lead smoke pollution is avoided. This method has the characteristics of simple technics and pollution-free process.

First claim

What is claimed is:

1 . A comprehensive recovery method of silver lead slag comprising:
(1) Purification: add silver lead slag into ammonia-ammonium chloride solution, keep warm and stir, after filtration, the residue removal and the impurity removal solution are obtained; (2) De-leading: ammonium bicarbonate is added into the obtained purification liquid in (1), de-lead residue and de-lead solution were obtained by filtration; (3) Recovery and filtration: de-lead solution obtained in (2) is added into methanol to proceed silver reduction. methanol:silver is 1:4˜1:6 in molar ratio, after filtration, silver powder and reduced liquid were obtained, the solution after filtration is returned to (1) to process purification. (4) Dissolving lead: residue removal obtained in (1) is added into sodium chloride-hydrochloric acid solution, lead powder is added to process lead dissolve, after that, lead pulp is obtained; (5) Hot filtration: lead pulp obtained in (4) is heating filtrated to obtain lead-soluble slag, this slag is recovered by tri-chlorination; (6) Cooling filtration: lead-soluble slag obtained in (5) is cooling down to room temperature to obtain lead chloride and coolant, coolant is returned to (4) to process lead dissolving. (7) Washing: de-lead residue obtained in (2) is washed by ammonium hydroxide until there is no silver contains in washing liquid to obtain lead carbonate, washing liquid is returned to (1) to process purification. (8) Hot decomposition: process hot decomposition for lead carbonate which is obtained in (7), red lead product is obtained when decomposition temperature is 450° C.˜500° C., decomposition time is 1˜2.5 h; yellow lead product is obtained when decomposition temperature is 550° C.˜650° C., decomposition time is 1˜2.5 h; smoke generated during hot decomposition is returned to (2) to process de-leading.

2 . A comprehensive recovery method of silver lead slag in claim 1 comprising: the composition of ammonia water-ammonium chloride solution in step (1) is: the mass percentage concentration of ammonia in ammonia solution is 5%˜15%, ammonium chloride is 200˜400 g/L, the solid mass ratio between ammonia-ammonium chloride solution and silver-lead slag solution is 5:1˜30:1, reaction temperature is 30° C.˜60° C., reaction time is 2-5 hours.

3 . A comprehensive recovery method of silver lead slag in claim 1 comprising: ammonium bicarbonate added in step (2) is a room temperature saturated solution, the adding process is not ended until there is no precipitation appears.

4 . A comprehensive recovery method of silver lead slag in claim 1 comprising: in step (4) the solubility of sodium chloride is 200 g/L˜300 g/L, PH in solution is 0˜0.5.

5 . A comprehensive recovery method of silver lead slag in claim 1 comprising: in step (4), liquid-solid ratio between sodium chloride-hydrochloric acid solution and residue removal is 20:1˜30:1, reaction temperature is 65° C.˜95° C., reaction time is 1-3 hours, 1 the reaction process always controls the pH of the reaction solution from 0˜1, the amount of lead added is 0.5 g/L-3 g/L.

Assignees

• Univ Beijing Technology

Inventors

• Pan De'An
• Wu Yufeng
• Li Liquan

Classifications

• C22B13/045

  Recovery from waste materials · CPC title

• C22B7/04 Primary

  Working-up slag · CPC title

• C22B7/008

  by an alkaline or ammoniacal leaching · CPC title

• C22B11/042 Primary

  Recovery of noble metals from waste materials · CPC title

• Y02P10/20

  Recycling · CPC title