The Effect of Boron Forms on the Crystallization Process of Lithium Carbonate

The present study investigates the effect of low concentrations of boron on the crystallization of lithium carbonate (Li 2 CO 3 ). Experimental results indicate that the boron in brine mainly exists in the forms of boric acid (B(OH) 3 ) and borate anion (B(OH) 4 − ). Temperature and pH are critical factors to adjust the ratio of B(OH) 3 and B(OH) 4 − . Meanwhile, the density functional theory calculation results suggest that the interaction of B(OH) 4 − with Li + is stronger than that of B(OH) 3 with Li + . Based on this result, the effect of boron on the crystallization of Li 2 CO 3 is investigated and discussed at different added forms of boron, added amount of sodium hydroxide, temperatures, and concentrations of boron. B(OH) 4 − is proved to be the form of boron that has significant influence. Temperature and amount of sodium hydroxide have significant influence on the balance of B(OH) 3 and B(OH) 4 − . The boron content of Li 2 CO 3 significantly decreases as the temperature increases, and that at 80 °C is 133 ppm while that at 25 °C is 397 ppm. And that increases as n NaOH / n B increases. Finally, effect of addition of polyhydric alcohols on reducing boron entrainment is investigated.