Ferruginous lime is the name given to burnt lime (CaO) coated with di-calcium ferrite (2CaO·Fe_2O_3). Its high degradation strength, its resistance to hydration and its capacity for fast and complete solution of fluxes in the BOF and EAF make it extremely attractive as a steelmaking flux.The objectives of the present work were to assess the feasibility of producing ferruginous lime in a rotary-kiln-type reactor and to deter mine the operating conditions favourable both for the formation of a hydration resistant product and the minimisation of problems such as accretions and agglomeration within the reactor.With respect to processing conditions, the trials suggest that ferruginous lime should be generated using a peak reaction temperature of 1260 deg C and allowing 45 min at greater than 1200 deg C. The optimal oxide addition is 10 percent (referring to mass contents) of the limestone charge to the rotary lime kiln.When subjected to short duration hydrating conditions i.e. 30 min in contact with steam at 100 deg C (as per ASTM specification X6) the ferruginous lime product exhibited good resistance to hydration (relative to pure CaO) and moderate physical degradation.Laboratory tests demonstrated the significantly enhanced rate and degree of dissolution of ferruginous lime (cf. uncoated lime) in a steel- making slag.
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