Speciation of Mn in electric arc furnace clinker

Co-producing clinker and steel during electric arc furnace (EAF) steelmaking is an emerging pathway to reduce carbon emissions in cement production. However, several elements in steel may compromise EAF clinker performance. This study investigated the distribution of Mn in EAF clinker produced from normal steel scrap. The results reveal that these EAF clinkers contained 7–8 wt% Mn oxide and Mn in divalent and trivalent forms. The average Mn fractions substituting for Ca, Si, and Al in calcium silicate and aluminate phases were below 3.4 wt%, but up to 7.2 wt% in brownmillerite, Ca 4 (Al 1-x-y Fe x Mn y ) 4 O 10 , generally with y < 0.25. Most (44–58 wt%) of the Mn was distributed in the RO phase (i.e. divalent metal oxide solid solution), consistent with the thermodynamic modelling results. These findings demonstrate that Mn can be incorporated into several EAF clinker phases, which is an important initial step to understanding and controlling the effects of Mn on EAF clinker properties such as reactivity.