Method of purifying sodium bromide from waste circuit boards pyrolysis coke

Patent metadata

Field	Value
Publication number	US-2022356067-A1
Application number	US-202217867618-A
Country	US
Kind code	A1
Filing date	Jul 18, 2022
Priority date	Dec 25, 2019
Publication date	Nov 10, 2022
Grant date	—

Abstract

A method for producing and purifying sodium bromide using the coke from waste circuit boards pyrolysis residues as reducing agent, belonging to the field of purifying sodium bromide and high-value utilization, and more particularly, relating to a method for reducing and purifying crude bromine salt obtained from waste circuit boards smelting ash by using the coke in waste circuit boards pyrolysis residues. The main steps are as follows: carbonization conversion, water dissolution, filtration, and concentrated crystallization under vacuum heating. The pure sodium bromide was obtained by reducing crude bromine salt enriched from waste circuit board smelting ash by using the coke in waste circuit boards pyrolysis residues, realizing the resource coupling and high-value utilization of the two wastes, avoiding the secondary pollution in the process of recycling the waste circuit boards. It has the characteristics of simple operation, high resource utilization rate and no tail liquid discharge.

First claim

1 . A method for producing and purifying sodium bromide using coke from waste circuit boards pyrolysis residues as reducing agent, characterized by the following specific steps:
(1) carbonization conversion: crude bromine salt is mixed with the coke separated from the waste circuit boards pyrolysis residues to obtain a mixture; the crude bromide salt is a by-product obtained from waste circuit boards smelting ash through sulphating roasting-alkali washing-neutralization precipitation and evaporation crystallization, which contains NaBr, NaBrO and NaBrO 3 ; the mixture is heated to obtain carbon monoxide and a primary product of sodium bromide containing NaBr and C from the coke; the carbon monoxide is collected and used as raw material of water gas; during mixing, the mass of the coke is 0.1˜1.0 kg per kilogram of the crude bromine salt, the temperature is 250˜450° C., and the time is 1.0˜2.0 h; (2) water dissolution and filtration: the primary product of sodium bromide obtained in step (1) is added to distilled water for dissolution and filtration to obtain insoluble impurities which contain C and NaBr which contains leachate; (3) concentrated crystallization under vacuum heating: the NaBr obtained in step (2) is concentrated and crystallized by vacuum heating to obtain sodium bromide (NaBr); this step is carried out in a vacuum evaporation device, which includes an evaporator, a solvent collecting tank and a vacuum system; the evaporator is communicated with the solvent collecting tank and the vacuum system respectively, a condenser and a material head tank are arranged on the evaporator and respectively communicated with the same, and the vacuum system is communicated with the condenser and the solvent collecting tank respectively, so that pressure in the condenser can be kept balanced with that of the solvent colleting tank and liquefied solvent in the condenser flows into the solvent collecting tank automatically.

2 . A method for producing and purifying sodium bromide using the coke from waste circuit boards pyrolysis residues as reducing agent according to claim 1 , characterized in that, during the water dissolution and filtration, a liquid-solid volume/mass ratio of distilled water to the primary product of sodium bromide is 8:1˜3:1 (L/kg), the temperature is 50˜80° C., and the time is 20˜60 min.

3 . A method for producing and purifying sodium bromide using the coke from waste circuit boards pyrolysis residues as reducing agent according to claim 1 , characterized in that, during the concentrated crystallization, the time is 30˜60 min and the temperature is 60˜150° C.

Assignees

• Univ Beijing Technology

Inventors

• Wu Yufeng
• Liu Gongqi
• Pan de-an

Classifications

• C22B26/10 Primary

  Obtaining alkali metals · CPC title

• C22B1/04

  Blast roasting · CPC title

• Y02P10/20

  Recycling · CPC title

• C01D3/16

  by precipitation or adsorption {(C01D3/145 takes precedence)} · CPC title

• C01D3/10 Primary

  Bromides · CPC title