A METHOD OF SEPARATING AND RECOVERING BROMINE FROM PRINTED CIRCUIT BOARD INCINERATION ASH BY TWO-STEP PROCESS

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.

Claims

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.sup.3, after adding sodium peroxide, stir 0.5-2 hours.

Description

THE APPENDED DRAWING

[0014] FIG. 1 is the flow chart of two-step separation and recovery of bromine from circuit board incineration ash.

PREFERRED EMBODIMENT

Embodiment 1

[0015] (1) First alkali leaching: proceed first alkali leaching for circuit board incineration ash in sodium hydroxide solution, where the mass concentration of sodium hydroxide is 5%, solid-liquid ratio of ash to leach solution is 1:10 Kg/L, leaching temperature is 55° C., leaching time is 0.5 h, first leaching residue and first leaching solution is obtained after filtration;

[0016] (2) Secondary alkali leaching: water is added to first leaching residue obtained in (1) for secondary alkali leaching, solid-liquid ratio of first leaching residue and water is 1:5 Kg/L, leaching temperature is room temperature and add sodium peroxide in leaching process, solid-liquid ratio of sodium peroxide and water is 20:1 Kg/m.sup.3, after adding sodium peroxide, stir 0.5 hours, and filter to get secondary leaching residue and secondary leaching solution, secondary leaching residue is gathered for treatment;

[0017] (3) Lead and Zinc removal: combine first leaching solution obtained in (1) and secondary leaching solution obtained in (2) to obtain combined leaching solution, the mass ratio of first leaching solution and secondary leaching solution is 1:3, add 98% industrial concentrated sulfuric acid to combined leaching solution until the pH of the combined solution reaches 6.5, lead-zinc removal residue and lead-zinc removal solution are obtained by filtration;

[0018] (4) Bromide evaporation and crystallization: proceed evaporation and crystallization for lead-zinc removal solution obtained in (3), crude bromide is obtained;

[0019] (5) Lead separation: add lead-zinc removal residue obtained in (3) into water, solid-liquid ratio of lead-zinc removal residue and water is 1:1 Kg/L, add 98% industrial concentrated sulfuric acid with stirring until the solution pH is 4.5. Filter to get lead sulfate and lead separation solution;

[0020] (6) Zinc evaporation and crystallization: proceed evaporation and crystallization for lead separation solution obtained in (5), crude zinc sulfate is obtained.

[0021] Recovery rates of bromide are 98.3%, lead 97.1% and zinc 98.3%.

Embodiment 2

[0022] (1) First alkali leaching: proceed first alkali leaching for circuit board incineration ash in sodium hydroxide solution, where the mass concentration of sodium hydroxide is 15%, solid-liquid ratio of ash to leach solution is 1:15 Kg/L, leaching temperature is 75° C., leaching time is 1 h, first leaching residue and first leaching solution is obtained after filtration;

[0023] (2) Secondary alkali leaching: water is added to first leaching residue obtained in (1) for secondary alkali leaching, solid-liquid ratio of first leaching residue and water is 1:10 Kg/L, leaching temperature is room temperature and add sodium peroxide in leaching process, solid-liquid ratio of sodium peroxide and water is 50:1 Kg/m.sup.3, after adding sodium peroxide, stir 2 hours, and filter to get secondary leaching residue and secondary leaching solution, secondary leaching residue is gathered for treatment;

[0024] (3) Lead and Zinc removal: combine first leaching solution obtained in (1) and secondary leaching solution obtained in (2) to obtain combined leaching solution, the mass ratio of first leaching solution and secondary leaching solution is 3:1, add 98% industrial concentrated sulfuric acid to combined leaching solution until the pH of the combined solution reaches 8, lead-zinc removal residue and lead-zinc removal solution are obtained by filtration;

[0025] (4) Bromide evaporation and crystallization: proceed evaporation and crystallization for lead-zinc removal solution obtained in (3), crude bromide is obtained;

[0026] (5) Lead separation: add lead-zinc removal residue obtained in (3) into water, solid-liquid ratio of lead-zinc removal residue and water is 1:2 Kg/L, add 98% industrial concentrated sulfuric acid with stirring until the solution pH is 6. Filter to get lead sulfate and lead separation solution;

[0027] (6) Zinc evaporation and crystallization: proceed evaporation and crystallization for lead separation solution obtained in (5), crude zinc sulfate is obtained.

[0028] Recovery rates of bromide are 99.3%, lead 99.5% and zinc 99.3%.

Embodiment 3

[0029] (1) First alkali leaching: proceed first alkali leaching for circuit board incineration ash in sodium hydroxide solution, where the mass concentration of sodium hydroxide is 10%, solid-liquid ratio of ash to leach solution is 1:12 Kg/L, leaching temperature is 65° C., leaching time is 1 h, first leaching residue and first leaching solution is obtained after filtration;

[0030] (2) Secondary alkali leaching: water is added to first leaching residue obtained in (1) for secondary alkali leaching, solid-liquid ratio of first leaching residue and water is 1:8 Kg/L, leaching temperature is room temperature and add sodium peroxide in leaching process, solid-liquid ratio of sodium peroxide and water is 35:1 Kg/m.sup.3, after adding sodium peroxide, stir 1 hours, and filter to get secondary leaching residue and secondary leaching solution, secondary leaching residue is gathered for treatment;

[0031] (3) Lead and Zinc removal: combine first leaching solution obtained in (1) and secondary leaching solution obtained in (2) to obtain combined leaching solution, the mass ratio of first leaching solution and secondary leaching solution is 1:1, add 98% industrial concentrated sulfuric acid to combined leaching solution until the pH of the combined solution reaches 7, lead-zinc removal residue and lead-zinc removal solution are obtained by filtration;

[0032] (4) Bromide evaporation and crystallization: proceed evaporation and crystallization for lead-zinc removal solution obtained in (3), crude bromide is obtained;

[0033] (5) Lead separation: add lead-zinc removal residue obtained in (3) into water, solid-liquid ratio of lead-zinc removal residue and water is 1:1.5 Kg/L, add 98% industrial concentrated sulfuric acid with stirring until the solution pH is 5. Filter to get lead sulfate and lead separation solution;

[0034] (6) Zinc evaporation and crystallization: proceed evaporation and crystallization for lead separation solution obtained in (5), crude zinc sulfate is obtained.

[0035] Recovery rates of bromide are 97.8%, lead 98.2% and zinc 99.1%.

Embodiment 4

[0036] (1) First alkali leaching: proceed first alkali leaching for circuit board incineration ash in sodium hydroxide solution, where the mass concentration of sodium hydroxide is 5%, solid-liquid ratio of ash to leach solution is 1:15 Kg/L, leaching temperature is 55° C., leaching time is 1 h, first leaching residue and first leaching solution is obtained after filtration;

[0037] (2) Secondary alkali leaching: water is added to first leaching residue obtained in (1) for secondary alkali leaching, solid-liquid ratio of first leaching residue and water is 1:5 Kg/L, leaching temperature is room temperature and add sodium peroxide in leaching process, solid-liquid ratio of sodium peroxide and water is 50:1 Kg/m.sup.3, after adding sodium peroxide, stir 0.5 hours, and filter to get secondary leaching residue and secondary leaching solution, secondary leaching residue is gathered for treatment;

[0038] (3) Lead and Zinc removal: combine first leaching solution obtained in (1) and secondary leaching solution obtained in (2) to obtain combined leaching solution, the mass ratio of first leaching solution and secondary leaching solution is 2:1, add 98% industrial concentrated sulfuric acid to combined leaching solution until the pH of the combined solution reaches 8, lead-zinc removal residue and lead-zinc removal solution are obtained by filtration;

[0039] (4) Bromide evaporation and crystallization: proceed evaporation and crystallization for lead-zinc removal solution obtained in (3), crude bromide is obtained;

[0040] (5) Lead separation: add lead-zinc removal residue obtained in (3) into water, solid-liquid ratio of lead-zinc removal residue and water is 1:1 Kg/L, add 98% industrial concentrated sulfuric acid with stirring until the solution pH is 6. Filter to get lead sulfate and lead separation solution;

[0041] (6) Zinc evaporation and crystallization: proceed evaporation and crystallization for lead separation solution obtained in (5), crude zinc sulfate is obtained.

[0042] Recovery rates of bromide are 96.9%, lead 96.8% and zinc 97.2%.

Embodiment 5

[0043] (1) First alkali leaching: proceed first alkali leaching for circuit board incineration ash in sodium hydroxide solution, where the mass concentration of sodium hydroxide is 15%, solid-liquid ratio of ash to leach solution is 1:10 Kg/L, leaching temperature is 75° C., leaching time is 0.5 h, first leaching residue and first leaching solution is obtained after filtration;

[0044] (2) Secondary alkali leaching: water is added to first leaching residue obtained in (1) for secondary alkali leaching, solid-liquid ratio of first leaching residue and water is 1:10 Kg/L, leaching temperature is room temperature and add sodium peroxide in leaching process, solid-liquid ratio of sodium peroxide and water is 20:1 Kg/m.sup.3, after adding sodium peroxide, stir 2 hours, and filter to get secondary leaching residue and secondary leaching solution, secondary leaching residue is gathered for treatment;

[0045] (3) Lead and Zinc removal: combine first leaching solution obtained in (1) and secondary leaching solution obtained in (2) to obtain combined leaching solution, the mass ratio of first leaching solution and secondary leaching solution is 1:2, add 98% industrial concentrated sulfuric acid to combined leaching solution until the pH of the combined solution reaches 6.5, lead-zinc removal residue and lead-zinc removal solution are obtained by filtration;

[0046] (4) Bromide evaporation and crystallization: proceed evaporation and crystallization for lead-zinc removal solution obtained in (3), crude bromide is obtained;

[0047] (5) Lead separation: add lead-zinc removal residue obtained in (3) into water, solid-liquid ratio of lead-zinc removal residue and water is 1:2 Kg/L, add 98% industrial concentrated sulfuric acid with stirring until the solution pH is 4.5. Filter to get lead sulfate and lead separation solution;

[0048] (6) Zinc evaporation and crystallization: proceed evaporation and crystallization for lead separation solution obtained in (5), crude zinc sulfate is obtained.

[0049] Recovery rates of bromide are 97.2%, lead 99.1% and zinc 96.1%.

Embodiment 6

[0050] (1) First alkali leaching: proceed first alkali leaching for circuit board incineration ash in sodium hydroxide solution, where the mass concentration of sodium hydroxide is 12%, solid-liquid ratio of ash to leach solution is 1:14 Kg/L, leaching temperature is 70° C., leaching time is 1 h, first leaching residue and first leaching solution is obtained after filtration;

[0051] (2) Secondary alkali leaching: water is added to first leaching residue obtained in (1) for secondary alkali leaching, solid-liquid ratio of first leaching residue and water is 1:6 Kg/L, leaching temperature is room temperature and add sodium peroxide in leaching process, solid-liquid ratio of sodium peroxide and water is 30:1 Kg/m.sup.3, after adding sodium peroxide, stir 1.5 hours, and filter to get secondary leaching residue and secondary leaching solution, secondary leaching residue is gathered for treatment;

[0052] (3) Lead and Zinc removal: combine first leaching solution obtained in (1) and secondary leaching solution obtained in (2) to obtain combined leaching solution, the mass ratio of first leaching solution and secondary leaching solution is 2.5:1, add 98% industrial concentrated sulfuric acid to combined leaching solution until the pH of the combined solution reaches 7.5, lead-zinc removal residue and lead-zinc removal solution are obtained by filtration;

[0053] (4) Bromide evaporation and crystallization: proceed evaporation and crystallization for lead-zinc removal solution obtained in (3), crude bromide is obtained;

[0054] (5) Lead separation: add lead-zinc removal residue obtained in (3) into water, solid-liquid ratio of lead-zinc removal residue and water is 1:1.6 Kg/L, add 98% industrial concentrated sulfuric acid with stirring until the solution pH is 5.8. Filter to get lead sulfate and lead separation solution;

[0055] (6) Zinc evaporation and crystallization: proceed evaporation and crystallization for lead separation solution obtained in (5), crude zinc sulfate is obtained.

[0056] Recovery rates of bromide are 99.1%, lead 98.0% and zinc 96.9%.