ABSTRACT
I. INTRODUCTION
Phosphate operations in Florida account for three-fourths of the phosphate production in the United States and are major contributors to world phosphate supplies (Terichow and May, 1973). In 1927 introduction of the flotation process for phosphate recovery revolutionized the industry but created a massive phosphate clay disposal problem. The slimes, or waste-clay suspensions, possess colloidal characteristics that make them difficult to dewater (Smelley and Feld, 1979). The fine particulate clays from the beneficiation process are discharged at a rate of 3.6 million metric tons per year per plant in an aqueous slurry of about 5% solids. These clay-wastes are stored in dams for settling; natural settling usually requires more than a decade to accomplish. These storage dams are an environmental hazard and an economic liability. Many laboratory techniques are available for dewatering of the slimes; however, none of these techniques is well-enough engineered to be economically practicable when applied in the field (Terichow and May, 1973; Lamont et al., 1975; Staff, 1975; Smelley and Feld, 1979). The primary settling problem with phosphatic slimes is attributed to attapul-gite, a fibrous clay mineral with a cardboard-like structure.
