ESSC & DUPLEX 2019

Several disposal options exist for waste products from steelmaking operations. The production of Cr-containing steels requires specific attention since slags and dust generated in melting processes often contain water-soluble Cr(VI). Due to the toxicity of hexavalent Cr landfill options are usually not considered feasible. Regulators apply concentration limits in respective leachates. Important parameter deciding on safe disposal is Cr(VI) which can be manipulated by appropriate treatment concepts and products. KRONOS ecochem is a supplier of iron salts dealing with environmental issues already since 1974. Besides offering solutions for water treatment the company is strongly involved in the cement industry providing products and expert service for Chromate reduction. With MKN Technologies they expanded their field of Fe-salt use to new applications, namely the metal industry with production of FeCr and Cr-alloyed steels. Utilising MKN’s stainless steelmaking expertise melting shop processes have been investigated where KRONOS ecochem technology is able to adequately address Cr(VI) issues. After identifying problem zones and determining toxicity levels suitable process steps were developed. Transferring learning points and methodology from cement operations assisted in specifying equipment and procedures needed to facilitate Chromate reduction. This paper discusses how stainless steelmaking dust is successfully treated enabling subsequent safe disposal by landfill. Main focus is given to the sustainability of Cr(VI) conversion, user-friendliness of the process and economical attractiveness of the entire concept.