Reversible flocculation and deflocculation of ball clays

One of the main usages of ball clays is in the pottery industry. However, in order to transport the clay suspensions from the mine site, some distance away from the consumer, dewatering of the clay suspension must be performed. The main restriction is that any dewatering treatment must not interfere in obtaining deflocculated, free flowing suspensions required by the pottery manufacturer.Investigations in the flocculation/deflocculation of these clay suspensions, resulted in finding a technique capable of achieving both requirements. The technique employs flocculation by an anionic flocculant in the presence of 10 mM of magnesium sulfate, thus achieving the dewatering step. When the magnesium sulfate was removed from the flocculated suspensions by simply washing the filter cake, good deflocculation of the clay suspension was achieved at alkaline pH. The role of MgSO₄ in the flocculant adsorption/flocculation, and subsequently in the flocculant desorption/deflocculation, was discussed.