Processing of mineral part of refined ferrochrome slags to obtain pelleted porous heat insulator

Abstract

In the wastes of the joint stock Aktobe Ferro-alloy plant, there are over 12 mln ton of refined ferrochrome slags that contain significant amounts of the metal dorebead. Dust-like mineral part of the slagof refined ferrochrome mainly consists of di-calcium silicate contaminated with poisonous compounds of hexatomic chrome. The metal can be separated from the mineral part by air separation and screen sizing, while the mineral part of the slag can be very efficiently mixed with Kazakhstani ferri-ferrous diatomite(opoka) and fluid glass and thermally processed to obtainglass-like heat insulating material. Being heated up to t ≥ 1000оС Di-calcium silicate interacts with finely divided ferrumdioxyde and hydrated silica to formporous glass phase of ferro-silica-calcium compounds that strengthen the heat-processed pellets against any mechanical influence. It was found that the optimum conditions for pellet production are: the ratio of diatomite ore to the mineral part of the RFX slag 2: 1, because at other ratios, the formation of a rolling glass-phase pellet is observed, the processing temperature is 1050 ° C, because at lower temperatures there is practically no formation of a glass phase. The compounds of hexatomic chrome het destroyed at heating and dissolve in the glass mass where they become insoluble. It is shown that the mineral part of RFX slags due to the relatively high content of calcium and silicon oxides is a valuable raw material for the production of granular porous heat-insulating material. The proposed technology makes it possible to extract a high-value metal component of RFX slags in the form of an expensive metal concentrate of refined ferrochromium and to obtain porous pellet fillers for reinforced concrete products.