Concentration of Swarnarekha river sand for Steel Foundry purposes

Abstract

A Sample of Swarnarekha river sand, received from M/s Telco, assayed 82.10 percent SiO2, 8.05 percent Al2O3, 2.76percent Fe2O3, 0.97 percent CaO, 0.96 percent MgO, 3.21 percent alkalies, 0.29 percent TiO2, with 0.73 percent loss on ignition. The gangue minerals present were feldspar (microcline and soda plagioclase varieties), hornblende, muscovite and chlorite. It was required to produce a quartz concentrate of high fusion point suitable for steel foundry purposes, without at the same time grinding the sand to any extent beyond the absolute minimum, as this would increase the A.F.A. grain fineness number and decrease permeability. It was found that a high grade silica concentrate could be prepared from the river sand as a flotation tailing, after a rough grind, to remove ferruginous coating from the mineral surfaces and to expose fresh surface. The recovery was quite attractive. The reagents required for flotation include however, hydrofluoric acid and Armac CD (Armour & Co.) both of which would have to be imported.