Electrically augmented vacuum filter system for dewatering slurries - with permselective membrane around anode and opt. cathode to prevent contamination of slurry by anions

摘要

A system for dewatering a suspension of particulate solids e.g. hydrous kaolin clay comprises an electrically augmented vacuum filter of the known type (see US4168222) which has been modified by incorporation of a perm-selective membrane in the housing surrounding the anolyte chamber. This membrane is pref. a perfluorosulphonic acid polymeric film and permits passage of cations from the anolyte into and through the filter cake and the suspension while preventing passage of anions and gaseous anolyte prods. A similar membrane may be incorporated into the catholyte chamber housing. The system is esp. for use in dewatering hydrous kaolin clay slurries to about 70% solids for transportation. The membrane prevents contamination of the filter cake by undesirable species, e.g. hydroxyl ions which impart to the prod. an excessively high viscosity and low specific resistance. The prod. can be tailored to various end uses, e.g. in paper coating or paint formulation.