1 Chloride Removal from Kraft Liquors Using Ion Exchange Technology

A new system has been developed for removal of chloride contamination from kraft process liquors. The compact, skid-mounted system which utilizes ion exchange columns only 24 inches in height, is shown to be capable of removing 90-99% of the chloride from a wide variety of sources including dissolved ESP catch, oxidized white liquor, spent bleach scrubber liquors, spent ion exchange demineralizer regenerants and caustic soda makeup. By removing chloride contamination, these liquors can be recycled to kraft recovery without causing a chloride buildup. By lowering the chloride content in kraft liquors, the sticky temperature of recovery boiler deposits can be significantly increased, which should lead to reduced pluggage and boiler down-time. Selectivity of the ion exchanger for chloride is extremely high and recovery of other chemicals such as sodium sulfate, sodium carbonate and sodium hydroxide is demonstrated to be typically 92-98%. Regeneration of sodium chloride from the resin is achieved with only water (ie. no chemicals), so that operating costs are negligable.