A new method of red mud recycling in the process of hot metal pretreatment

Abstract

To realize a large-scale consumption of red mud in the steelmaking industry, a new recycling method was investigated through the pre-reduction roasting experiment and the slag-metal interaction experiment simulating the hot metal pretreatment process in the steelmaking industry. In virtue of the sensible heating of the hot metal and the reducibility of [C] and [Si], the iron could be separated and recovered from the pre-reduced red mud pellets into the hot metal directly with a recovery rate exceeding 75%. With the composition adjustment of the residual oxides in the pre-reduced red mud (PRRD) using CaO and Al2O3 or aluminium dross (AD), a slag having a low melting point (below 1300 °C) and a high sulfide capacity (lgCS = −2.3) was formed, and more than 94% of [S] in the hot metal could be removed into this slag through the slag-metal interaction. The desulfurization efficiency of the flux (PRRD-CaO–Al2O3; PRRD-CaO–AD) is approximate to the traditional desulfurizing flux (CaO–CaF2). The advantages of this method are summarized as the low energy cost and the slag valorization.