GB1480261A - Dry scrubbing tar ladened reduction cell off gases to remove fluorides - Google Patents

Abstract

1480261 Removing fluoride and carbonaceous matter from gases KAISER ALUMINUM & CHEMICAL CORP 16 Oct 1974 [24 Oct 1973] 44876/74 Heading C1A Gaseous fluorides and condensable carbonaceous matter are removed from a gaseous stream by introducing pulverulent alumina into the stream so as to cause at least part of the carbonaceous matter to condense on the alumina, directing the alumina-containing gaseous stream through a foraminous plate into a chamber which contains a turbulent mass of pulverulent alumina and subsequently removing all particulate matter from the gas stream. The process is particularly applicable to the treatment of the off-gases from an aluminium reduction cell having a horizontal stud Soderberg anode. In a preferred embodiment the off-gases from the reduction cells are passed through a conduit 14 wherein alumina is dispersed into the stream from hopper 19. The mixture is directed upwardly through the dispersing foraminous plate 12, through the turbulent mass of pulverulent alumina maintained above the plate and then through the filter bags 13 for particulate removal. The gas is then vented through conduit 21 to the atmosphere or other treatment facilities. Periodically the filter bags are agitated to remove build-up of particles. Alumina is discharged from the chamber 11 through conduit 20. All of the alumina discharge may be fed to the reduction cell but may be recycled to the gaseous stream in conduit 14. Tar coated alumina discharged from the reactor may be passed through a combustion chamber to burn off carbonaceous contaminants before passage to the reduction cell.