Master of Engineering
University of Wollongong. School of Mechanical, Materials and Mechatronic Engineering
Swinnerton, Mark, The influence of slag evolution on BOF dephosphorisation, Master of Engineering thesis, University of Wollongong. School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, 2005. http://ro.uow.edu.au/theses/282
A study has been conducted to examine the influence of slag evolution on BOF dephosphorisation. An experimental technique was developed where slag/metal emulsion samples were obtained from the BOF during processing.
The observed evolution of slag composition was consistent with many previous studies, where in the first half of the blow slags high in (%SiO2) and low in (%FeO) are generated. During the second half of the oxygen blow, (FeO) generation and lime dissolution improve the slag basicity and contribute to the transfer of phosphorus from metal to slag.
Poor levels of phosphorus removal during the centre region of the blow were found to coincide with a minimum in the (%FeO) composition. By the end of blow, 70% of the mass of phosphorus in the furnace is present in the slag, and the extent of phosphorus removal is proportional to the slag basicity and the (%FeO) concentration in the slag.
By utilizing mass balance calculations to estimate the mass of slag in the furnace, it was shown that at tap, approximately 30% of lime and 50% of magnesia remain undissolved in a liquid slag saturated in both components. It was concluded that the mass of lime added to the furnace could be reduced without influencing the dissolved concentration of (%CaO), and therefore without deteriorating the extent of dephosphorisation.
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