Towards a new process for the flotation of quartz

• Quartz can be floated in diluted HF solutions simply by the aid of frothers.
• The floated quartz is significantly purer than the corresponding feed materials.
• The results could be important for production of high purity quartz concentrates.

Results obtained from flotation experiments performed on three different quartz concentrates demonstrate that quartz can be floated in diluted solutions of hydrofluoric acid (HF) simply by the aid of frothers alone. The recovery was found to be highly dependent on the choice of frother and strongly positively correlated with the concentration of both frother and HF, as well as with the HF conditioning time. Experiments using HNO3 instead of HF showed no flotation of quartz. Of the five different frothers tested, Brij 58 was found to produce the highest recovery. Good recoveries were also obtained for Dowfroth 400 and Flotanol C07, whereas Dowfroth 200 and MIBC failed to float any quartz. From experiments in which a given feed material were tested at two different particle size distributions it was found that highest recoveries were obtained for the finer feed. Chemical analysis of the floated products showed that these were significantly purer than their corresponding feed materials, and that most of the contaminating elements were concentrated in the sink fraction that remained in the cell. Contact angle measurements corresponded well with flotation recoveries.