Patent ID: 6156191
Filing Date: 2000-12-05
Classification: C02F,Y10S

Abstract:
An apparatus for the continuous removal of selenium from a selenium containing aqueous stream comprising:a heat exchanger for maintaining the temperature of the selenium containing aqueous stream at a temperature between 80 and 90.degree. C. to give a cooled selenium containing aqueous stream;a means for introducing the selenium containing aqueous stream into the heat exchanger;a first reactor wherein the selenium containing aqueous stream is mixed with an aqueous ferric salt containing solution to form a first mixture;a means for introducing the cooled selenium containing aqueous stream from the heat exchanger into the first reactor;a pH controller for regulating the addition of the aqueous ferric salt containing solution to the first reactor so as to maintain the pH of the first mixture between approximately 4.0 to 4.2;a second reactor wherein the first mixture is mixed with an aqueous permanganate salt solution to oxidize the selenium compounds to give a second mixture, wherein said second mixture contains selenium containing solids;a means for introducing the first mixture from the first reactor into the second reactor;a ratio flow controller for adjusting the addition of the aqueous permanganate salt solution to the second reactor so as to maintain a fixed ratio to the flow rate of the first mixture into the second reactor;means for separating the selenium containing solids from the second mixture by centrifugation thus giving a an aqueous stream having a reduced selenium content; andmeans for the automatic metered addition of an aqueous base containing solution to the aqueous stream having a reduced selenium content to increase the pH of the centrifuged liquid stream to approximately 6.0 to 8.0.