Attempted reduction of Iron content from Clay and limestone samples from A.C.C. for cement manufacture

Abstract

A sample of dry mix (mixture of limestone and clay) assaying 0.64% Fe (0.91% Fe2O3)was received at the instance of the Associated Cement Companies Ltd., Bombay for reduction of its Fe content at least to 0.42% after ignition. Straight magnetic separation of the table concentrate did not yield a non-magnetic product having an appreciably lower iron content. The clay sample which constituted about 15% of the above mix and assayed 1.22% Fe was then investigated separately. Straight tabling and magnetic separation did not yield any satisfactory result. Reduction roast followed by magnetic separation of the sample after heating in an oxidising atmosphere also proved unsuccessful in reducing the iron content. Electrostatic separation and flotation methods again did not yield product appreciably lower in iron content than in the original sample. The limestone sample consisting about 85% of the dry mix had an iron assayed of 0.33%. this was again attacked separately but straight magnetic separation at different sizes did not help in reducing its iron content. No methods can therefore be recommended for treating the mix or its separate constituents to give the desired results.