Rationalization of the flotation circuit of an Egyptian phosphorite plant

The current deterioration in the Sebaiya West phosphate flotation plant was confirmed in the laboratory to be due to inefficient liberation in the - 0 .25 mm ground product and to the presence of calcite gangue mineral. Phosph oconcentrates assaying from 26.9-27.8% P2O5 with recovery of 50-55% were ob tained from a nm-of-mine having 20.3% P2O5 using sulfonated fatty acid, pur e oleic acid or cationic fatty amine acetate-alcohol mixture as a selective silica collector Double calcite silica flotation gave better results and a cleaner concentrate assaying 29.2% P2O5 was obtained using H3PO4 as a phos phate depressant in the former circuit and the sulfonated;fatty acid as a c ollector. The concentrate grade increased to 30.70% P2O5 by using the catio nic silica flotation circuit at an overall recovery of about 68%. Fine grin ding of the flotation feed to less than 0.15 mm followed by desliming on 0. 04 mm screen led to a relative improvement concentrate grade to about 32% P 2O5 but with an overall recovery of 52.8% P2O5,. Super-phospho-concentrates assaying about 34.8% P2O5 and 1.32% acid insolubles (I.R) were obtained by double calcite-silica flotation of the -0.1 +0.04 mm finely ground ore but at an overall recovery of 46.6%. This increased to 72.6% with a correspond ing decrease in the concentrate grade to about 30% P2O5 by just silica flot ation only using the sulfonated fatty acid. However, when this single flota tion step was conducted using the cationic silica collector at pH 8 the con centrate grade increased to an average 31.5% P2O5 with an overall recovery of about 67%. Comparative cost estimate of the different flotation regimes indicated that the cationic silica flotation of the finely ground Sebayia W est phosphate is the least expensive with total reagents costs of only 1.71 Sit less than half the current cost of the plant using the agricultural by -product rice bran oil without taking into account the grinding costs of th e ore to less than 0.1 mm.