Patent ID: 8337571

Claim:
A method for reducing the content in water-soluble impurities originating from a waste which is used before a crystallization step in a manufacturing process that produces a crystalline product comprising sodium carbonate, sodium sulfite, or sodium bicarbonate, the method comprising the following steps: providing a waste comprising water-soluble impurities selected from the group consisting of silicates, organic foam-causing agents, and combinations thereof, performing a magnesium treatment on at least a portion of said waste to form a treated solution, said treatment comprising adding a magnesium compound to the waste in order to form water-insoluble matter with at least a portion of said impurities, wherein when the waste is in solid form, the waste is dissolved in an aqueous medium before or after the magnesium treatment; passing a liquor comprising at least a portion of said treated solution though at least one separation unit to obtain a purified solution; and forming crystals comprising sodium carbonate, sodium sulfite, or sodium bicarbonate by performing at least the following step: passing at least a portion of the purified solution in a reactor and/or a crystallizer under conditions suitable to form said crystals.