Research on boron recovery from sulfate-type saline lakes with a novel dilution method

A novel dilution method was developed to extract boron from sulfate-type salt lake brine in the Qinghai Tibet plateau. The boron-concentrated brine was prepared by evaporation after magnesium removal using Na2SO4·10H2O solid. The extraction process parameters such as boron concentration, dilution ratio, temperature, initial precipitation time, aging time, and extraction efficiency of boron were tested. The results showed that the solution pH after dilution with deionized water increased from 4.2 to 8.0, indicating dissociation of polyborate ions in brine by hydrolysis to give monoborate species and hydroxide ions. The initial precipitation time and aging time were observed to be strongly influenced by the boron concentration, dilution ratio, and temperature. A low temperature, high boron concentration and moderate mass dilution ratio (water/brine) were beneficial to boron extraction, allowing for an extraction efficiency of more than 80%. The only salts that precipitated from diluted brine were magnesium borates. The obtained results indicated the application potential of the novel technology of boron extraction from salt lake brine.