Extraction of magnesium from salt pond waste with low lithium grade using sodium silicate reagent

Abstract

Abstract Nowadays, Indonesia’s salt production process has shifted from a traditional salt pond process to a salt pond with a geomembrane tarpaulin system. This system has the advantage of producing a faster salting process and a better salt quality and producing a thick yellow liquid waste known as bittern. The waste produced has not been fully utilized, even though the waste contains valuable elements, namely magnesium, lithium, and others. This paper investigates the potential utilization of bittern by extracting magnesium from by-product salt pond using sodium silicate reagent with various concentrations of 125–250 g/l. The bittern used in this experiment had the chemical composition as follows: 33,184 ppm magnesium (Mg), 23,787 ppm sodium (Na), 6.1 ppm lithium (Li), 5,491 ppm potassium (K), 617 ppm calcium (Ca), 152 ppm boron (B). The highest removal of magnesium ion by addition of sodium silicate of 250 g/l was about 96.2%. The results showed that the solid products were magnesium silicate precipitates without containing asbestos compounds. The magnesium silicate precipitate product can be applied as talc raw material for the pharmaceutical industry.