US 12,330,955 B2
Method for recovering high-purity sodium bromide from bromine-containing crude salt
Dean Pan, Beijing (CN); and Guanjun Li, Beijing (CN)
Assigned to BEIJING UNIVERSITY OF TECHNOLOGY, Beijing (CN)
Appl. No. 17/626,805
Filed by Beijing University of Technology, Beijing (CN)
PCT Filed Sep. 18, 2021, PCT No. PCT/CN2021/119297
§ 371(c)(1), (2) Date Jan. 12, 2022,
PCT Pub. No. WO2022/160742, PCT Pub. Date Aug. 4, 2022.
Claims priority of application No. 202110120746.6 (CN), filed on Jan. 28, 2021.
Prior Publication US 2024/0010507 A1, Jan. 11, 2024
Int. Cl. C01D 3/10 (2006.01); B01D 9/00 (2006.01); B01D 11/04 (2006.01)
CPC C01D 3/10 (2013.01) [B01D 9/0018 (2013.01); B01D 11/0488 (2013.01); B01D 11/0492 (2013.01)] 4 Claims
OG exemplary drawing
 
1. A method for recovering high-purity sodium bromide from bromine-containing crude salt, comprising steps are as follows:
(1) immersion and filtration: immersing bromine-containing crude salt in tap water and filtering the tap water with the immersed bromine-containing crude salt to obtain an immersion solution and an immersion residue, wherein a ratio of volume of tap water to mass of the bromine-containing crude salt is 3:1-5:1 L/kg, the bromine-containing crude salt is immersed for 10-20 minutes under 25-35° C. to obtain the immersion solution and the immersion residue, in which the mass ratio of bromine-containing crude salt is 5-25%;
(2) acidification and oxidation: performing an acidification and oxidation reaction by acidifying the immersion solution obtained in step (1) with 36% concentrated hydrochloric acid, and then adding sodium chlorate to the immersion solution while stirring the immersion solution, wherein a pH of the immersion solution is maintained at 0-1 with the concentrated hydrochloric acid to obtain an acidification oxidation solution and acidification oxidation gas, an amount of the added concentrated hydrochloric acid is 0.4-0.8 L/L of the immersion solution, an amount of the added sodium chlorate is 10-20 g/L of the immersion solution, a time of the acidification and oxidation reaction is 30-60 min, and a temperature of the acidification and oxidation is 25-35° C.;
(3) multi-stage extraction: subjecting the acidification oxidation solution obtained in step (2) to a multi-stage extraction with carbon tetrachloride, wherein a volume ratio of the carbon tetrachloride to the acidification oxidation solution is 1.5:1-2.5:1, and a number of extraction stages in the multi-stage extraction is 2-5 with 2-8 min extraction time and a temperature of the multi-stage extraction is 25-35° C., wherein an extract solution and a raffinate obtained as a result of the multi-stage extraction, and wherein the raffinate is evaporated and crystallized to obtain crude sodium bromide for centralized treatment;
(4) cooperative back extraction: performing a cooperative back extraction reaction by adding a back extractor to the extract solution obtained in step (3) while stirring the extract solution, and when a pH of the extract solution reaches 6-7, stopping adding the back extractor, and continuing the cooperative back extraction reaction for 5-10 minutes at 25-35° C. to obtain an organic phase and a back extraction solution; and
(5) evaporative crystallization: subjecting the back extraction solution obtained in step (4) to evaporative crystallization to obtain sodium bromide, wherein a temperature of the evaporative crystallization is 110° C.-140° C.