Process for making basic sodium and/or potassium aluminum sulphates and for making paper with such

摘要

A process in which a leach liquor of Al2(SO4)3+K2SO4+Fe2SO4 and other sulphates is introduced to a surface-cooled crystallizer that drops the Al2(SO4)3+18H2O. The leach liquor is pumped through a heat exchanger that keeps a temperature of 160 DEG F. and the surface temperature of the surface-cooled crystallizer is maintained at 60 DEG F. The temperature gradient within the leach liquor promotes crystal formation. These crystals are then supplied to mixture which includes K2SO4 in a simple crystallization and evaporation step that uses a vacuum of twenty inches of mercury and heat to drop Al2(SO4)3+K2SO4+24H2O. A pressure of 250 PSI and a temperature of 200 DEG C. are then applied in a discrete continuous process that yield a basic sodium or potassium aluminum sulphate and excess sodium sulphate or potassium. The excess sodium sulphate or potassium sulphate is returned to the simple crystallization and evaporation step. The basic sodium aluminum sulphate comprises particles that are at least forty percent below two micron. This is then applied to a delaminator that converts eighty-five percent of the particles to under two micron. The BKAS and/or BNaAS is used as a filler in the making of paper.