Characterization and Thermal Treatment of Electric Arc Furnace Dusts Generated During Steel Production in Peruvian Industries

Gómez-Marroquín M.C.; D´Abreu J.C.; de Avillez R.; Letichevsky S.; Terrones-Ramires A.J.; Phatti-Satto K.J. · Minerals, Metals and Materials Series (2022) · DOI: 10.1007/978-3-030-92563-5_33

Resumen

Self-reduction is a pyrometallurgical treating process that aims to valuable metal recovery from mining-metallurgical industry wastes, mainly from steelmaking industries. Electric Arc Furnace Dusts (EAFD) are still the most attractive materials to be tested in using this technique, due to their high magnetite and franklinite/zinc ferrite contents. This research will address the reuse of these co-products in steel plants, providing added value to this material that until now is constituted as an environmental liability of considerable economic importance in steelmaking industries. Chemical and microstructural analysis has determined high contents of iron and zinc from magnetite and franklinite/zinc ferrite. Iron was present in the non-stoichiometric form of “hapkeite” (Fe1.34Si0.06) in both EAFD 1 and EAFD 2. A rare appearance of Moissanite CSi –2H was also found in EAFD 1. Thermogravimetric evaluations allowed elimination of almost 15% of volatile matter at 1000 °C in EAFD 1. EAFDs were partially reduced and showed a high porosity, which would make it possible for the recovery of its main metal content by carbothermic self-reduction. Proximate analysis and carbon dioxide reactivity of two reductants were tested for evaluating the behavior of selected reductants in carbothermic self-reduction of EAFDs using a procedure given by the Steelmaking and Ironmaking Group of DEQM PUC/RJ. This mixture included 85% (EAFD + coal), 6% CPV ARI, and 9% water. Operational Diagram of Phase Predominance (ODPP) from the Zn–Fe–C–O system was used to calculate the required carbon and to guarantee the occurrence of the global chemical reactions of carbothermic reduction either in franklinite/zinc ferrite as in magnetite by 100% CO and temperatures between 1000 and 1100 °C. In these conditions, self-reducing briquettes of EADF 2 lost more weight so reacted faster than EAFD 1. Finally, reactions rates of carbothermic self-reducing briquettes EAFDs were very fast during the first 5 min and retarded from 5 to 40 min.

Instituciones: Universidad Nacional de Ingeniería