Classification of BOF Slag by Data Mining Techniques According to Chemical Composition

In the process of converting pig iron into steel, some co-products are generated—among which, basic oxygen furnace (BOF) slag is highlighted due to the great amount generated (about 126 kg of BOF slag per ton of steel grade). Great efforts have been made throughout the years toward finding an application to minimize the environmental impact and to increase sustainability while generating added value. Finding BOF slag valorization is difficult due to its heterogeneity, strength, and overall swallowing, which prevents its use in civil engineering projects. This work is focused on trying to resolve the heterogeneity issue. If many different types of steel are manufactured, then different types of slag could also be generated, and for each type of BOF slag, there is an adequate valorization option. Not all of the slag can be valorized, but it can be a tool for reducing the amount that must go to landfill and to minimize the environmental impact. An analysis by means of data mining techniques allows a classification of BOF slag to be obtained, and each one of these types has a better adjustment to certain valorization alternatives. In the plant used as an example of the application of these studies, eight different slag clusters were obtained, which were then linked to their different potential applications with the aim of increasing the amount valorized.

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

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.