Effect of pyrophyllite on the precipitation of aluminium sulphate during the dissolution of aluminosilicates by acid mixtures

Abstract

The dissolution of silicate rocks with hydrofluoric-sulphuric-nitric acid mixtures has been studied. When the samples contained pyrophyllite in addition to other silicoaluminate minerals, the pyrophyllite was not attacked and part of the aluminium dissolved and separated from the other minerals and was precipitated as aluminium sulphate with different degrees of hydration.