FACTORAL DESIGN FOR COLUMN FLOTATION OF PHOSPHATE WASTES

Abstract

ABSTRACT The results of column flotation of fine particles of phosphate are presented in this paper. A factorial design was used to study effects and their interactions of the main parameters affecting column efficiency. Three-phase experiments were performed using a mixture of fatty acid and fuel oil as a collector for phosphate while pine oil was used as a frother, The results of 3-phase experiments were correlated to bubble diameter and air holdup. The results showed that factorial design of column flotation experiments and their analysis gave an insight on the effect of column parameters on grade and recovery of concentrates. From a feed sample containing about 7.8 % P2O5 (˜ 17.1% BPL) and 78.5 % silica, it is possible to obtain concentrates with different grade (23.4-29.0 % P2O5) and recovery (54.9-80.2%) depending on the operating conditions. Increasing frother concentration increased air holdup and in turn decreased bubble diameter. This caused a significant improvement for grade and recovery. Also, increasing superficial air velocity increased air holdup but the bubble size was increased with a resultant of improving the recovery at the expense of grade. The order of significant of the main effects of variables for grade was as follows: superficial wash water velocity (X3) > frother concentration (X2) > superficial air velocity (X1), whereas the order of significance of the main effects of variables for recovery was as follows: superficial air velocity (X1) > frother concentration (X2) > superficial wash water velocity (X3). The interaction between each two parameters is also determined.