Optimization by Using the Taguchi Method of Boric Acid Production by Dissolving Flash Calcined Colemanite in Water Saturated with SO۲

Turkey has the largest boron reserves in the world with a rate of approximately ۷۲%. The most common commercial boron reserves in Turkey are colemanite, tincal, and ulexite. Boric acid, which is the most commonly used boron compound in Turkey, is obtained from the dissolution of colemanite with sulfuric acid. In the present study, an aqueous medium saturated with sulfur dioxide instead of sulfuric acid was used in order to obtain boric acid.  Colemanite ore was flash calcined at various temperatures and optimum dissolution conditions of the ore obtained in water saturated with SO۲ were examined via the “Taguchi Method”. In the trials, flash calcination temperature (۵۰۰, ۶۰۰, ۷۰۰, ۸۰۰ °C), reaction temperature (۵۰, ۶۰, ۷۰, ۸۰ °C), solid-liquid ratio (۰.۱۵, ۰.۲۰, ۰.۲۵ and ۰.۳۰ g/mL), grain size (-۵۰۰+۳۵۵, -۳۵۵+۲۱۲, -۲۱۲+۱۵۰, and -۱۵۰ µm), and reaction time (۱۵, ۳۰, ۴۵, and ۶۰ minutes) were selected as the parameters and velocity of gas flow and mixing speed were considered as constant in all the experiments. In addition, experiments were carried out at atmospheric pressure. Accordingly, optimum conditions were found as flash calcination temperature of ۵۰۰oC, reaction temperature of ۵۰oC, grain size of -۲۱۲+۱۵۰ µm, solid-liquid ratio of ۰.۳۰ g/m, and reaction time of ۶۰ minutes. The estimated dissolution under these conditions was ۹۹.۴۷% and dissolution of ۱۰۰% was obtained in the experiments conducted. The aim of the study was to obtain more economical and high-purity boric acid compared to sulfuric acid via an environmentally friendly process without any waste.

کلیدواژه ها:

Sulfur dioxide ، flash calcination ، calcined colemanite ، Optimization ، boric acid