The acid decomposition of silicate minerals part I. Reactivities and modes of dissolution of silicates

Factors determining the modes of dissolution and reactivities of silicates in acids are discussed. Under the action of acids, ortho-, pyro- and cyclosilicates decompose with dissolution of metal cations and silica. In contrast, partial decomposition of the chain, sheet and framework silicates is the normal result of acid attack. This leads to dissolution of metal cations and leaves a siliceous residue. Silicate reactivity is determined by a combination of structural factors and the properties of the metal cation of the silicate. Complexing of the metal ion with anions is capable of enhancing the dissolution rate of metal silicates in acids. Cases where silicate reactivity is determined by diffusion processes or by properties of the ore containing the silicate are considered.