Resource-Saving Technology of Recycling of Wastes of Secondary Aluminium Production in a Blast Furnace in the Process of Aluminous Slag Smelting

Abstract

The paper considers the theoretical and practical aspects of recycling of secondary aluminium production wastes by adding them to the burden mix in the process of aluminous slag production (from bauxites) in the blast-furnace smelting operation. The comparative analysis of bauxite chemical composition and the secondary aluminium production waste was carried out and the feasibility of using secondary aluminium production waste as a raw material for blast-furnace smelting was studied. A mathematical model was presented to obtain aluminous slag by blast-furnace smelting of bauxites with their partial substitution with the secondary aluminium production waste; this model makes it possible to calculate the rational mixture of burden materials when aluminous slag is produced in a blast furnace taking into account chemical composition of the materials used and the required content of oxides of aluminium, calcium and silicon in the final slag. The high-alumina slag formed when the wastes of secondary aluminium production are used in burden materials is characterized by low gas content during slag tapping (in spite of the elevated temperature) and by high flowability. The laboratory tests of binding properties of the high-alumina slag obtained in a blast furnace using wastes of secondary aluminium production, which were carried out by the plant laboratory, showed that the cements produced from this slag have satisfactory strength characteristics, although their setting time is somewhat longer. Recycling of slag dumps of aluminium production will make it possible to obtain new sources of raw materials, enhance the technology of handling and transportation of materials from man-made mineral formations to recycling plants without increasing the environmental load.