Reuse of slags from integrated steelmaking

ended

The main points of focus of the project will be the internal recycling of a Fe-enriched BOF slag fraction as a substitute for raw material as iron ore fines for the sinter plant and the external use of a Ca- and P enriched BOF fraction as high valuable cement additive and fertilizer. A new processes chain will be developed to increase the reuse. At the BOF slag special emphasis will be laid on a new process route to concentrate the Fe-content and reduce the P-content in the substitute. The route comprises a primary liquid Fe-enrichment by slag recirculation and secondary solid and dry Fe-enrichment processes. The enrichment processes take benefit from differences of physical and chemical slag properties as density, viscosity, solidification properties, magnetic susceptibility, hardness and thermal expansion. The secondary Fe-enrichment consists of a microwave assisted comminution of the BOF slag, selective grinding and dry magnetic separation. The secondary Enrichment step will multiply the Fe-concentration in the substitute of the primary step and further reduce the P-content. Simultaneously the quality of the Ca-rich non magnetic fraction will be improved. Due to the dry processing of the BOF slag the produced Ca-rich fractions will keep the hydraulic properties. On this basis the Ca-rich fractions will be evaluated for an external use in the cement industry as a raw meal in clinker production and as alternative reactive cement main constituent. Also the external use of the CaO-rich fraction from magnetic separation as lime fertilizer will be evaluated. The internal and external reuse concepts of SLAGREUS will be assessed regarding the environmental and economic advantages.