Abstract
Deoxidation, desulphurisation and inclusion modification are some of the essential features in secondary steel refining through injection of calcium alloy in the form of a cored wire. It is imperative that the filling material must be consumed by the melt to the maximum extent in order to make this cored wire alloy addition cost effective and efficient. In this connection study of calcium recovery is an important issue, which may provide guidelines to select the optimum operating parameters from a fundamental basis. The present study is based on plant data from Tata Steel, Jamshedpur, India. The results demonstrate that maximum calcium recovery is achievable at an optimum speed of the cored wire. Dimensional analysis was carried out to analyse the plant data and the calcium recovery was found to correlate well with physically sound dimensionless numbers such as Biot number, the dimensionless bath temperature and the relative rate of silicon to sulphur transfer from/to the added calcium silicide in the melt. A correlation has also been obtained between the calcium recovery and various dimensionless parameters. The efficacy of calcium addition is also assessed through characterisation of inclusions by scanning electron microscopy and energy dispersive X-ray spectroscopy.
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