Recovery process in a pulp mill

A substantial and increasing problem with the pulping chemical recovery system, is the presence of chloride and potassium in the spent liquor entering the recovery boiler. Chloride and potassium increase the stickiness of carryover deposits and dust particles to the recovery boiler tubes, which accelerate fouling and plugging in the upper part of the recovery boiler. The present invention relates to a process by which the content of potassium ions in a recovery system for pulping chemicals can be reduced. The process comprises bringing spent liquor to a recovery boiler, burning said spent liquor, collecting precipitator dust formed, forming a solution by dissolving the precipitator dust (9) in a liquid (2,31,71), where the solution of precipitator dust is subjected to a treatment with an inorganic ion exchange material (8) in order to remove at least a part of the potassium therein.