Sulphide and phosphide capacities of ferroalloy smelting slags
Date
2012-02-13
Authors
Saridikmen, Habib
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Abstract
In this study, the factors affecting sulphur distribution (Ls), phosphorus distribution
(Lp), sulphide capacity ( S ā2 C ) and phosphide capacity ( Pā3 C ) of ferrochromium
smelting slags were investigated under reducing conditions at 1600 oC. Also, sulphur
distribution (Ls) and sulphide capacity ( S ā2 C ) of ferromanganese smelting slags were
studied under reducing conditions at 1500 oC.
The results showed that the logarithms of sulphide capacities varied between -7.67 to
-9.28 and the logarithms of phosphide capacities were between -15.20 and -12.69 for
ferrochromium smelting slags. On the other hand the logarithms of sulphide capacities
of ferromanganese slags were found to be change between -7.63 and -8.11.
The experimental results indicated that CaO, SiO2, MgO and basicity ratio of the slags
were the main factors affecting phosphide and sulphide capacities of ferroalloy
smelting slags.
According to the results, the transfer of sulphur and phosphorus from metal to slag
phase increases with increase in the basicity ratio, calcium oxide and magnesium
oxide content of ferroalloys smelting slags. Also, it was found that sulphide and
phosphide capacities of ferroalloys smelting slags tend to decrease with increasing
concentration of silica in the slag phase.
Structural models based on binding energy of O-2 ions in the slag systems were
developed by using the linear relations among the logarithm of sulphide and
phosphide capacities of slags. In addition to these models, easy to use quadratic
multivariable regression model equations were developed in order to express sulphide
and phosphide capacities of the ferroalloy smelting slags and sulphur and phosphorus
partition ratios between slag and metal phases. These simple models which are
combination of regression and thermodynamic approaches can be used in industrial
ferrochromium and ferromanganese smelting operations. The usage of these models
can help ferroalloy smelting process engineers to predict sulphide and phosphide
capacities of the relevant slag systems.