Processing of boric acid from borax by a wet chemical method

Boric acid crystals were obtained from borax (Na2B4O7 · 10H2O) solutions which were prepared from borax ore. The concentration of borax solutions was varied from 1120 to 1240 kg/m3 and 1180 kg/m3 was determined to be the optimum concentration value for boric acid production from a relation between borax solution concentration and boric acid production yield and boric acid purity. Boric acid production yield was around 91% for a borax solution of 1180 kg/m3. Boric acid purity ranged from 94 to 97% for different concentrations before refining, and a high purity boric acid over 99.6% with low sulfate and sodium was obtained after refining. Boric acid crystals were characterized by X-ray diffraction, differential thermal and thermograrimetric analysis, and scanning electron microscopy observation.