Patent ID: 8324377

Claim:
A method of separating a water-soluble cellulose ether from an aqueous suspension, comprising the steps of: introducing a reaction mixture containing water-soluble cellulose ether particles having an average particle size of 0.1 to 2000 microns in diameter, into an agitator vessel containing water at or above a dissolution temperature, thereby producing an aqueous suspension including water and water-soluble cellulose particles; flowing said suspension, under pressure and at a temperature of 70° to 140° C., through a rotary pressure filter, said rotary pressure filter including a perforated, 0.2 to 2 mm thick, metal filter plate, said filter plate having perforations which were formed by electron beam machining, said perforations having sidewalls of differing pore pitch and a diameter that substantially corresponds to the average particle size of the water-soluble cellulose either particles; capturing said particles on said filter plate as a result of said flowing, thereby forming a cake of accumulated particles; ceasing said flowing; removing said cake from said filter plate; directing a stream of water under pressure through a jet nozzle at said filter plate after said cake has been removed in order to remove any remaining accumulations from said filter plate; and recycling the water that had been used to remove any remaining accumulations in order to use it for washing said cake.