Abstract:The reactivity of Na₂B₄O₇·5H₂O and Na₂B₄O₇ in non-aqueous HCl-CH₃OH solvent system was investigated. The effects of H₂O, CH₃OH/B mole ratio and reaction time on the reaction at room temperature were examined. Experimental results show that when Na₂B₄O₇·5H₂O and Na₂B₄O₇ are the reactants, the dissolved B₂O₃ contents are observed to be 98.2% and 99%, respectively, in 5 min at the CH₃OH/B mole ratio of 4. The decrease of water in the reaction medium was observed to increase the crystallization of NaCl in the order of Na₂B₄O₇>Na₂B₄O₇·5H₂O. It was also observed that the boron solution obtained after the reaction could be hydrolyzed by the addition of H₃BO₃. The results show that HCl-CH₃OH system is a more effective solvent compared to H₂SO₄-CH₃OH both in the reactivity and the shortened reaction time.

Key words: non-metallic ores; oxide ores; hydrometallurgy; leaching