Recovery of Boron from the Clay Waste of Boron Industry by Leaching

In this study, the recovery of boron from the clay waste of boron industry by leaching with sulfuric acid solution was studied in a batch reactor and the subsequent production of boric acid (H3BO3) was investigated. The effects of acid concentration, solid-to-liquid ratio and reaction temperature on the leaching process were examined. Experimental studies were carried out in the ranges of 0.1-1.0 M for acid concentration, 1-10 g/120 mL for solid-to-liquid ratio and 25-75 degrees C for reaction temperature. The analysis of the experimental data showed that the kinetics of the leaching process fitted the Avrami model in the form of X = 1 -exp (-k t (n)). For the production of boric acid, the optimum leaching conditions were determined as follows: acid concentration, 0.1 M; solid-to-liquid ratio, 6 g/120 mL; reaction temperature, 50 degrees C and reaction time, 60 min. Finally, boric acid was produced in the purity of more than 95% by crystallization of the leach solution.