关键词: 硼酸, 酸化沉淀, 离心萃取, 热溶结晶, 混合醇

Abstract: A study for extracting boric acid from high magnesium brines by a combined process incorporating acidic precipi- tation，centrifugal solvent extraction，and dissolution crystallization was performed using highly concentrated winter brine from the East Taijinar Salt Lake as feedstock.It was found that this process was capable of extracting boron from the brine in a thorough manner.For this purpose，the key to acidic precipitation was to manipulate acid dosage as per the boron level in the raw material.Centrifugal extraction was carried out using 25%（volume fraction） isooctanol+25% isoamyl alcohol+50% sul- fonated kerosene as the organic system，at pH was 1.5~2.0，O/A ratio was 2∶1，and centrifuge rotation speed was 2 400 r/min； after 3 stages of extraction and stripping，the extraction rate achieved 97.3% while stripping attained 99%.The resulting stripped liquor was used for dissolving the crude boric acid obtained from acidic precipitation whereby 99.8% high purity boric acid was produced after cooling crystallization.

Key words: boric acid, acidification-precipitation, centrifugal extraction, thermal dissolve-crystallization, mixed alcohol