REMOVAL OF SILICA FROM KAKUL ROCK PHOSPHATE BY DIRECT FLOTATION TECHNIQUE

Abstract

The Kakul rock phosphate deposits are not in a uniform grade. These include parts which are rich in phosphate (P2O3) and have silica (SiO2) in acceptable limits whereas some portions of these deposits contain low percentage of phosphate i.e. around 20% to 22% in average with a higher percentage of silica reaching to 36%. Therefore, the rock phosphate is extracted sorted and graded into high and low grades on the basis of percent of P205 and Si02 . The rich ore with high percentage of Pf )s and low percent of Si02 is directly transported for treatment. The low content phosphate rock with high percentage of silica is sometimes blended with very high grade phosphate to make it useable for making phosphate fertilizer but usually low grade mined phosphate rock is dumped as rejected material. The aim of this study was to investigate how to upgrade the phosporite content of the rejected material which should be acceptable for industrial use. To achieve this goal, flotation technique was selected and experiments were carried out to increase the percentage of P2O5 by reducing the percentage of silica content in the rock, either P205 was made liable to float and taken as froth or vice versa. Flotation concentration process has many parameters which effect the overall performance of this concentration process. Some of the most important variables including dosage of collector, depressant and pH of the pulp were investigated to see their effects with different values on the floatability of P2O5 or Silica and the remaining parameters were kept constant. The purpose was to get an optimum value of each variable for use in future test work so that this technique can be applied to a pilot plant. Tests were conducted under optimum conditions to observe the results and the recommendations were made for further studies on a pilot plant. It is observed in this direct flotation test work that the phosphate rock can be upgraded upto 29% of P203 and Si02 is reduced to 19%which meets the specifications of the fertilizer industry