Column Flotation of a South African Cooking Coal

Abstract

The aims of the study reported here were to investigate whether column notation technology could be used to recover a saleable quality coal from a −0.15 mm fines sample obtained from a Natal colliery producing a coking quality coal; and to determine which column cell operating parameters had a dominant effect on the yield and grade of concentrate produced. Seven parameters were investigated namely, froth height, frother concentration, air flow rate, volumetric slurry feed rate, wash water addition rate, sparger type and column height. Tests runs were performed according to a 2-level 2^7.3 IV fractional factorial design.

The test results showed that the column cell was capable of producing a concentrate grade of coking quality. Frother concentration was found to exert the largest effect on yield and grade; followed by air flow rate and slurry feed rate. It was concluded that the high vitrinite (85%) content of the coal sample caused the overall rate of flotation to be determined by froth phase kinetics. Comparative tests showed that, in general, the performance of the column cell was better than conventional flotation but poorer than results obtained from density-based float and sink separations.

Keywords:

• column flotation
• South African coal fines
• factorial design
• column parameters
• flotation kinetics
• vitrinite content

Additional information

Notes on contributors

S. T. VON HOLT

Presently at Solutions Technology (Pty) Ltd, P O Box 11, Steenberg, South Africa, 7947