A method of recovering bromide from bromine-containing smelting ash

A method of recovering bromide from bromine-containing smelting ash comprising:

• (1) leaching by sub-molten salt method:
• smelting ash containing bromine and sodium hydroxide is leached by sub-molten salt method in a sodium hydroxide system, leaching liquid and residue are obtained;
• (2) washing:
• wash the leaching residue obtained in step (1), a solid-to-liquid ratio of leaching residue:water is 1:5 to 1:10 Kg/L, water is at room temperature, washing liquid and washing residue are obtained, the washing residue is collected and treated;
• (3) separation of lead and zinc:
• merge the leaching liquid obtained in step (1) with the washing liquid obtained in step (2) to obtain a mixture, a volume ratio of leaching liquid:washing liquid is 1:3 to 3:1, add 98% industrial concentrated sulfuric acid to the mixture until the pH of the mixture reaches 6.5-8, lead-zinc separation residue and lead-zinc separation liquid are obtained;
• (4) membrane separation concentration:
• the lead-zinc separation liquid obtained in step (3) is separated and concentrated by reverse osmosis membrane to obtain concentrated solution and water, the water is returned to the washing step (2);
• (5) evaporation crystallization of bromine salt:
• the concentrated solution obtained in step (4) is evaporated and crystallized to obtain crude bromine salt;
• (6) lead separation:
• lead-zinc separation residue obtained in step (3) is mixed with water, a solid-to-liquid ratio of lead-zinc separation residue:water is 1:1 to 1:2 Kg/L, stir and add 98% concentrated industrial sulfuric acid until pH thereof reaches 4.5 to 6, and filter to get lead sulfate and lead separation solution;
• (7) evaporative crystallization of zinc:
• crude zinc sulfate is obtained by evaporation and crystallization of the lead separation solution obtained in step (6);