Lime – in the batch system, first a part of the lime was added, neat the required P2O5
then the remainder of the lime, to give a pH of 7.0 to 7.3 on the clarified liquor.
The amount of lime used ranges from 400 to 500 lb CaO per 106 lb melt, the average yearly figure for one refinery using Williamson clarification being 460 lb of CaO with 175 lb of P2O5 i.e. 635 ton per 106ton melt