The refining process, part 2: new data from Ynysfach Ironworks, Merthyr Tydfil
Abstract
Refining was an intermediate process for conversion of the grey cast iron produced by the smelting of, principally Coal Measures, iron ore into a white cast iron known as finers metal that was suitable for conversion to wrought iron by puddling. It was adopted first in Merthyr Tydfil in 1791, following the failure of Cort’s puddling process to produce good iron directly from coke pig. Refining entailed the remelting of the pig iron under strongly oxidising conditions, followed by rapid chilling of the iron. Archaeometallurgical analysis of samples from excavation of the 1830s–1870s refinery building of the Ynysfach Ironworks, Merthyr Tydfil, has permitted the first modern reappraisal of the refining process. The residues possessed a very high phosphorus content which generated an unusual mineralogy, including phosphoran varieties of the minerals olivine and iscorite. Dephosphorisation was a major function of refining.
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