Commercial Products from Phosphatic Clays: A Pre-Feasibility Study
A process was developed to make lightweight aggregates using phosphatic clays. In this process, dilute phosphatic clay slurry is first treated with a flocculant and a fibrous material, then dewatered on a screen, achieving about 20% solids. This mix is further dewatered using either a belt press or air drying to obtain a 50% solids paste, which is then extruded and fired at 900 oC in a kiln. The final product had a density as low as 1.4 gm/cm3 and crushing strength of over 1000 psi. Several processing routes are proposed. The cost for the most expensive flowsheet is about nine dollars (± 30%) per ton of aggregates.