The determination of bloomery furnace mass balance and efficiency

Abstract

Abstract A technique for the graphical solution of the ore:furnace lining:fuel ash mixture in the melt and the yield of the reaction during bloomery iron smelting is presented. The technique focuses on the so-called immobile elements, particularly the rare earth elements, but employs a wide range of elements. Previous attempts to determine ore sources from iron slag chemistry have generally examined the major and minor elements of the slags, but are complicated both by the significant, but variable, concentrations of some of these elements in charcoal and by the mobility of some major elements during weathering. The new approach has been developed to aid the provenancing of slags from the smelting of iron-ores from the Bristol Channel Orefield, which is characterized by high purity goethite/haematite ores with extremely low trace element concentrations. It is thus particularly important to understand the involvement of furnace lining in the melt, for this material will have the dominant contribution to the trace element chemistry. The mass balance approach is illustrated using smelting slags, furnace lining and roasted ore fragments from the Roman iron making town of Ariconium (near Ross-on-Wye, Herefordshire) and a good degree of compatibility of these materials is demonstrated.