A method of separating and recovering bromine from printed circuit board incineration ash by two-step process

Patent metadata

Field	Value
Publication number	US-2023192488-A1
Application number	US-201916627721-A
Country	US
Kind code	A1
Filing date	Jan 15, 2019
Priority date	Sep 17, 2018
Publication date	Jun 22, 2023
Grant date	—

Abstract

The invention relates to the field of efficient separation and recovery of bromine by full wet method, especially to a two-step separating method of bromide and recovery of lead and zinc from printed circuit board Incineration ash. It mainly includes first sodium hydroxide alkaline leaching, secondary sodium peroxide alkaline leaching, pH adjustment, separate lead and zinc, bromide evaporation and crystallization to recover crude bromide and other steps. Compared with traditional comprehensive recovery process of ash, the invention uses sodium hydroxide to dissolve bromide, lead and zinc, and uses the strong oxidation of sodium peroxide in alkaline environment, copper bromide and other bromine are oxidized and leached; through two-step method, the efficient leaching of bromine, lead and zinc is realized, silver and other precious metals are enriched at the same time. It is beneficial to subsequent recovery of precious metals and has the characteristics of short tail liquid discharge.

First claim

What is claimed is:

1 . A method of separating and recovering bromine from circuit board Incineration ash by two-step process:
(1) first alkali leaching: proceed first alkali leaching for circuit board incineration ash in a sodium hydroxide solution, first leaching residue and a first leaching solution are obtained after filtration; (2) secondary alkali leaching: add water to the first leaching residue obtained in step (1) for secondary alkali leaching, and filter to get secondary leaching residue and a secondary leaching solution, the secondary leaching residue is gathered for treatment; (3) lead and zinc removal: combine the first leaching solution obtained in step (1) and the secondary leaching solution obtained in step (2) to obtain a combined leaching solution, a mass ratio of the first leaching solution to the secondary leaching solution is 1:3-3:1, add 98% industrial concentrated sulfuric acid to the combined leaching solution until pH of the combined leaching solution reaches 6.5-8, lead-zinc removal residue and a lead-zinc removal solution are obtained by filtration; (4) bromide evaporation and crystallization: proceed evaporation and crystallization for the lead-zinc removal solution obtained in step (3), crude bromide is obtained; (5) lead separation: add the lead-zinc removal residue obtained in step (3) into water, solid-liquid ratio of the lead-zinc removal residue and water is 1:1-1:2 Kg/L, add 98% industrial concentrated sulfuric acid with stirring until pH reaches 4.5-6; filter to get lead sulfate and a lead separation solution; (6) zinc evaporation and crystallization: proceed evaporation and crystallization for the lead separation solution obtained in step (5), crude zinc sulfate is obtained.

2 . A method of separating and recovering bromine from circuit board Incineration ash by two-step process according to claim 1 , wherein a mass concentration of the sodium hydroxide is 5%-15%, a solid-liquid ratio of the circuit board incineration ash to the sodium hydroxide solution is 1:10-1:15 Kg/L, leaching temperature is 55-75° C., leaching time is 0.5-1 h.

3 . A method of separating and recovering bromine from circuit board Incineration ash by two-step process according to claim 1 , wherein a solid-liquid ratio of the first leaching residue to water is 1:5-1:10 Kg/L, leaching temperature is room temperature and add sodium peroxide in leaching process, a solid-liquid ratio of sodium peroxide and water is 20:1-50:1 Kg/m 3 , after adding sodium peroxide, stir 0.5-2 hours.

Assignees

• Univ Beijing Technology

Inventors

• Pan Dean
• Wu Yufeng

Classifications

• C22B7/02 Primary

  Working-up flue dust · CPC title

• C22B13/045

  Recovery from waste materials · CPC title

• C01G9/06

  Sulfates · CPC title

• C22B7/008

  by an alkaline or ammoniacal leaching · CPC title

• C22B19/24

  with leaching with alkaline solutions, e.g. ammonia · CPC title