Dry processing of borax by calcination as an alternative to wet methods

Beneficiation of borax in the Kirka concentrator, Turkey is presently accomplished by wet processing techniques involving scrubbing of the minus 6 mm borax to remove the undesirable clayey impurities followed by cyclone and spiral classification of the fine fraction. The fine borax tailings assaying as high as 20% B₂O₃ mostly below 0.2 mm is disposed into the environment. Over a quarter million tons of borax in the saturated brine have now accumulated in vast tailing ponds for a new remediation technology. In this study, a new alternative technology to wet processing is proposed. This technique encompasses the calcination of borax at 450°C to a maximum growth in size followed by fragmenting and air classification of the fine gangue minerals. Comparison of the wet and dry processing schemes reveals that the dry technique yields superior results in terms of the concentrate recoveries and tailings grade. The results of the air separator show a concentrate grade of 51.05% B₂O₃ with 93.75% recovery. A thermodynamic analysis conducted on pure borax along with other boron minerals is presented to explain the relationship between the maximum growth of borax and the optimum upgrading conditions. These results indicate that the dry processing not only provides a successful benefication scheme but also a plausible alternative for the abatement of the environmental pollution from boron concentrators.