Abstract: This invention relates to a process for the manufacture of crystal sugar from an aqueous sugar juice containing sugars and organic and mineral impurities, including Ca.sup.2+ and/or Mg.sup.2+ ions, such as a sugar cane or sugar beet juice, comprising the following operations:(a) concentration of said sugar juice to give a syrup, and(b) crystallization of said syrup to give a crystal sugar and a molasses,characterized in that it also comprises an operation:(c) of tangential microfiltration, tangential ultrafiltration or tangential nanofiltration, this operation being effected before operation (a).It also relates to a process for the production of crystal white sugar from a sugar juice of the sugar cane juice type, comprising the above-mentioned process for the production of crystal sugar, completed by re-melt, decolorization and crystallization operations.

Abstract: The invention relates to a process for softening an aqueous sugar juice containing sugars and Ca.sup.2+ and/or Mg.sup.2+ ions, such as a sugar factory molasses by means of a cation exchange resin, in the form of Na.sup.+ and/or K.sup.+, and for regeneration of said resin, comprising:(a) a softening step wherein the said sugar juice is brought into contact with the said cation exchange resin, in the form Na.sup.+ and/or K.sup.+, to give, on the one hand, a softened sugar juice depleted in Ca.sup.2+ and/or Mg.sup.2+ ions and charged with Na.sup.+ and/or K.sup.+ ions and, on the other hand, a cation exchange resin charged with Ca.sup.2+ and/or Mg.sup.2+ ions, and(b) a step for the regeneration of said latter resin,characterised in that the regeneration step (b) comprises bringing the said resin into contact with a liquid effluent produced on separation by chromatography of the sugars from a softened aqueous sugar juice containing sugars and Na.sup.+ and/or K.sup.