Impurity control and increasing of product yield in boric acid production process

Boric acid is produced in solution medium in accordance with the reaction between colemanite ore with sulfuric acid and then crystallized. However, due to the reactions of sulfuric acid with the side minerals contained in the ore, various sulfate salts (impurities) other than boric acid are formed in the solution medium. The aim of this thesis is to control the concentration of impurities in the boric acid process. For this purpose, the studies were designed in two different stages and thus the control of the impurity concentration in the process was provided. In the first stage studies, the reaction between colemanite ore with sulfuric acid was carried out in a semi- batch reactor. Since the semi-batch reactor provides the advantage of selectivity, the reaction rates of the side-minerals are reduced and the concentration of impurities in the medium is decreases. Experimental results revealed that the use of a semi-batch reactor is more advantageous than the use of batch reactor in terms of both efficiency and impurity control. In the semi-batch reactor, the product yield increased by at least 5 %, while the impurity concentration decreased by 40 % on average. The second stage studies were based on the adsorption of sulfate ions in the main solution. The main solution was obtained from Emet Boron Factories. For selective adsorption, chitosan bentonite biocomposite film was synthesized as adsorbent. In adsorption studies, it has been determined that the biocomposite adsorbent can remove sulfate with an adsorption capacity of approximately 300 mg/g.