Smelting experiments in the early medieval fajszi-type bloomery and the metallurgy of iron bloom

Abstract

Until the late middle ages iron was made from the iron ore in a one-step process in the small bloomery furnaces (direct production of iron).Due to the relatively low metallurgical temperature (1100-1300^o C) the product of this ancient technology was a spongy-structured solid iron mass with some slag, called iron bloom. During the past two years a team in a collaborated study with archaeologists set out to discover this ancient technology using experimental archaeology consisting of more than 20 smelting experiments.From these experiments the parameters of the technology (i.e. temperature, gas composition) were measured and the resulting iron ore, slag and iron bloom samples were examined (i.e. chemical, metallographic and mineralogical analysis). Based on the results of these smelting experiments, measurements and analysis, it is possible to draw some conclusions regarding the physical-chemical and metallurgical processes of the early medieval iron production.