Flotation of iron ore washing plant tailings

Abstract

Iron ore washing plant operations generally consist of sizing of the ore by dry / wet screening, scrubbing, washing, gravity concentration, magnetic separation and classification by hydrocyclones. All these physical separation processes are known to be sensitive to particle size, mineralogy, liberation and feed grade. Depending on the efficiency of the above operations or otherwise, iron values are lost in the form of fines and ultra fines into the tailing ponds. These fines / ultra fines had little commercial value in the past and accumulated in huge quantities over the years. As the high-grade deposits are getting exhausted and the demand for high grade finer material for pellet making is ever increasing, focus is shifting towards recovering the values from the erstwhile tailing ponds. Froth flotation is more suitable process under such circumstances. Flotation in general and Column Flotation in particular proved to be highly promising. The R&D efforts undertaken at CSIR - NML Madras Centre, India in this direction have been highlighted. Case studies on flotation / column flotation of iron ore washing plant tailings of varying silica and alumina content from different regions of India were discussed. The results clearly indicated the feasibility and significance of flotation process in adding value to washing plant tailings to obtain marketable concentrates. This is also supposed to mitigate to certain extent the environmental problems caused by the ever expanding and unmanageable tailing dams.