Study on preparation process of strontium rich functional salt from Zigong underground brine
Underground brine in Zigong contains rich sodium,magnesium,lithium bromide,strontium,etc.It can be used to produce raw salt,magnesium salt,bromine and other industrial products,which is an important liquid mineral resource for the alkali industry and salt industry.In response to the characteristics of rich strontium in underground brine in Zigong and the current status of salt production technology,strontium rich salt was developed.By optimizing oxalic acid as brine purify-ing agents,calcium and magnesium were removed from brine,and more strontium was retained.The optimized brine purifica-tion process was as follows:adding 5.2 mL of oxalic acid with concentration of 0.7 mol/L at a constant rate of 5 mL/min to 100 mL of brine at 45℃,adjusting the pH to 8.0,stirring for 30 min,adding 0.3 mL of polyacrylamide with mass concentra-tion of 2 g/L and molecular weight of 8 million,allowing the final solution to stand for 1 h.The strontium content in the table salt(100 g dry basis)prepared by high-temperature evaporation of purified brine obtained by optimizing the process was 37.5 mg,which was 20 times of the strontium content in the currently available table salt.The strontium salts and other in-dex requirements complied with the national standard(GB 2721-2015).The new process realized the comprehensive utili-zation of strontium in Zigong brine,and also provided citizens with the choice of strontium rich functional salts.
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