Patent ID: 8758556
Filing Date: 2014-06-24
Classification: C02F,D21C,Y10S

Abstract:
1. A method for inhibiting calcium salt scale formation in a chemical pulping process comprising adding an effective scale inhibiting amount of a composition to the alkaline aqueous mixture in the digester of said chemical pulping process and/or to the black liquor of a chemical pulping process, said composition consisting of at least one phosphonate component (I) selected from at least one of the compounds (i), (ii), (iii) and (iv), and at least one component (II) consisting of at least one carboxylated fructan compound, wherein compound (i) is at least one aminoalkylene phosphonic acid, or its corresponding aminoalkylene phosphonate salt, selected from compounds having the general formula (X) a [N(W)(Y) 2-a ] z wherein X is selected from C with the proviso that the aminoalkylene phosphonic acid (and its corresponding aminoalkylene phosphonate), contains, at least, two phosphonic acid (or corresponding phosphonate) groups; wherein compound (II) is at least one alkylene phosphonic acid, or its corresponding alkylene phosphonate, having the formula: wherein D is selected from C wherein compound (iii) is selected from at least one phosphono-alkane-polycarboxylic acids and its corresponding salts based on alkali, earth alkali, ammonium, and protonated amine ions, wherein the alkane moiety is a C wherein compound (iv) is selected from at least one linear or branched hydrocarbon chains having from 6 to 2,000,000 carbon atoms containing amino groups substituted by ZPO wherein the further component (II) consists of a carboxylated fructan component and is selected from the group of (a) carboxyalkylfructan having from 1 to 4 carbon atoms in the alkyl moiety, (b) dicarboxyfructan having a degree of oxidation (DO) of from 10 to 100% expressed as a molar percentage of monosaccharide units converted into the corresponding dicarboxy analogues, (c) 6-carboxyfructan, and/or (d) fructan polycarboxylic acid, having a degree of carboxyalkylation or carboxyacylation of from 0.2 to 3.0, or (e) mixtures thereof,