Electrostatic Processing of Mineral Salt Mixtures: The Selectively‐stimulated Contact Charging of Kieserite (MgSO₄ · H₂O). An Interpretation

Abstract

In th~electrostatic processing o~crude potash salt, a mixture of mainly KCl, NaCI and MgS0 4 · H 20, the single salt particles gain an electnc charge component-selectively on contact with each other. This enables the components to be separated in an electric field. The component-selective stimulation of contact charging can be achieved using a technology developed over many years, where small amounts of certain monocarboxylic acids are added to the salt mixture, while the relative humidity of the ambient air is maintained at some ?efimte value. -Recently a model has been proposed to elucidate the mechanism of stimulated contact charging. It has been applied In the case o~NaCI. H 20 molecules bonded in surface-cation-vacancies of the crystal have an important role in this model, which will b~extended In the 'p~esent work to th~case of the s~imulated contact charging of kieserite. This enables the interpretation of empirical diagrams characterising the electrostatic salt separation to be made for the first time. Conversely, this may be regarded as a convincing verification of the model itself.