Recycling of steelworks refractories: processing and properties

Abstract

The maintenance of several steel-making equipment of the Companhia Siderúrgica Nacional (CSN/ Brazil) builds up about 11 000 tons of refractory waste per year. Most of that refractory waste is disposed off in landfill sites without any application. That action permanently excludes an important alternative source of raw material from the productive cycle. In this context, in the particular case in CSN, all critical points of the generation cycle and recycling of refractory waste were investigated, aiming to use these residues as reprocessed raw material in the Refractory Industryreverse logistics. The project implementation, through an integrated solution, was technically and financially feasible with an economic return of about US$ 1 million per year in terms of net present value. The reuse of this refractory waste also minimises the environmental impact generated by the production, consumption and disposal of refractory materials from steel production.

Life Cycle Assessment Comparison of Two Refractory Brick Product Systems for Ladle Lining in Secondary Steelmaking

“…At this point, it is necessary to emphasize that the present analysis was performed on the production process of "pure" (i.e., not-recycled) bricks. However, it is expected that, in normal operating conditions, around 20% in weight of the raw materials to produce a new brick will come from the recycling process [32] (i.e., after the complete demolition of the internal lining of a ladle, part of the used bricks, not affected by the direct contact with steel nor by degradation, can be grinded and reused in the recipe), although alumina based larger grains would be preferred, depending on their market price [33]. As far as it is expected the same amount of recycled materials for both types of bricks, corresponding environmental impacts will be reduced accordingly, except for the emissions of volatile organic compounds (VOCs) in the MgO-C type, since the phenolic resin must be added and fired necessarily and except for air emissions (in particular CO/CO 2 , NO x ) and energy consumption consequences, during firing/sintering; in brief, the environmental consequences of the production phase would maintain similar figures even adopting recycling for both types.…”