VERFAHREN ZUR HERSTELLUNG VON KAOLINGEGENSTÄNDEN

摘要

A method of concentrating solids in an aqueous clay slurry (15) is disclosed wherein liquid in the slurry is removed by contacting the aqueous clay slurry (15) with a semi-permeable membrane (80), preferably by passing the dilute aqueous slurry (15) of beneficiated kaolin along a surface of a semi-permeable membrane (80), while imposing a pressure differential across the membrane surface whereby water molecules are caused to pass through said semi-permeable membrane (80) which is substantially impervious to the passage of clay solids therethrough, but pervious to the passage of water molecules, ions and dissolved salts therethrough. The aqueous kaolin slurry (17) having passed over the membrane surface is collected separately from the permeate as a more concentrated aqueous slurry of beneficiated fine-particle size kaolin particles. The filtrate (75) contains only ions and dissolved salts, such as the sulfates and chlorides of iron, potassium, calcium or sodium, but is substantially free of carry over clay solids, that is no solids or so little solids that the need to further process the filtrate liquid (75) to recover clay solids, which is necessary when using conventional dewatering equipment, is eliminated.