METHOD OF ION-EXCHANGE PURIFICATION OF SEWAGE WATERS FROM NONFERROUS METALS Russian patent published in 1998 - IPC

FIELD: ion-exchange purification of industrial sewage waters, in particular, sewage waters of electroplating processes from ions of nonferrous metals. SUBSTANCE: method includes treatment of sewage water with solution of ammonia to attain pH 10.5-11.0 to produce excessive NH₄OH and separate ions of nonferrous metals in two groups. One of two groups forms soluble ammonia complexes, while the other, precipitates in the form of hydroxides. Then operation of holding for 3-45 min of solution is carried out with excessive content of NH₄OH in contact with carboxyl cationite in the form of hydrogen, loaded in sorption column. Solution is supplied to the upper part of column to 1/3-1/4 height of cationite layer to perform transition of the upper layer of cationite from hydrogen to ammonia form capable of sorption of ions of nonferrous metals from solution treated with ammonia in flow conditions. Used for the purpose is sorption column of the simplest design. EFFECT: higher efficiency. 3 tbl