Method for preparing alkali metal bicarbonate particles

Abstract

A method for preparing alkali metal bicarbonate particles by crystallization from an alkali metal carbonate and/or bicarbonate solution with an additive present in the solution, chosen from among sulfates, sulfonates, polysulfonates, amines, hydroysultaines, polycarboxylates, polysaccharides, polyethers and ether-phenols, alkali metal hexametaphosphate, phosphates, sulfosuccinates, amidosulfonates, amine sulfonates, preferably chosen from among polysaccharides, and such that the additive is present in the solution at a concentration of at least 1 ppm and preferably at most 200 ppm.

1 . A method for preparing alkali metal bicarbonate particles, comprising crystallization of alkali metal bicarbonate particles starting from a solution of alkali metal carbonate and/or bicarbonate in the presence of an additive in the solution, wherein:
 the additive is selected from the following compounds:
 alkyl ether sulfates; 
 isopropylamine dodecylbenzene sulfonate; 
 polyethers or ether-phenols selected from the group consisting of:
 polyethylene glycol mono(tristyrylphenyl) ether; 
 ethoxylated oleyl alcohols; 
 branched octylphenoxy poly(ethyleneoxy)ethanols; 
 ethoxylated polyarylphenols; 
 
 sulfosuccinates; 
 aminosulfonates selected from the group consisting of N-methyltaurine, sodium N-methyltaurinate, and isopropylamine dodecylbenzene sulfonate; 
 organophosphates or phosphonates selected from the group consisting of:
 polyoxyethylene alkylether phosphates, whose alkyl chain advantageously comprises from 6 to 20 carbons; 
 poly(oxy-1,2-ethanediyl),.alpha.-(dinonylphenyl)-omega-hydroxy-phosphate; 
 alkyl-phosphonic or hydroxyalkyl-phosphonic acids of semi-structural formula ((HO) 2 OP)—R with R being an alkyl group or hydroxyalkyl group, or salts thereof; 
 alkyl-diphosphonic acids of semi-structural formula ((HO) 2 OP)—R—(PO(OH) 2 ) with R being an alkyl group or a hydroxyalkyl group, or salts thereof; 
 nitrilo-alkyl-phosphonic acids of semi-structural formula ((HO) 2 OP—R) 3 —N with R being an alkyl chain with 1 to 5 carbons, or salts thereof; 
 
   and wherein the additive is present in the solution at a concentration of at least 1 ppm.   
     
     
         2 . The method as claimed in  claim 1 , wherein the additive is present at a concentration of at most 200 ppm. 
     
     
         3 . The method as claimed in  claim 1 , wherein crystallization of alkali metal bicarbonate particles is carried out by cooling the solution. 
     
     
         4 . The method as claimed in  claim 3 , wherein cooling of the solution is carried out between 70° and 30° C. 
     
     
         5 . The method as claimed in  claim 1 , wherein crystallization of alkali metal bicarbonate particles is carried out by carbonation of the solution with carbon dioxide. 
     
     
         6 . The method as claimed in  claim 1 , wherein carbonation of the solution is carried out at a temperature of at least 20° C. and at most 95° C. 
     
     
         7 . The method as claimed in  claim 1 , wherein crystallization of alkali metal bicarbonate particles is carried out by evaporation of at least a portion of the solution. 
     
     
         8 . The method as claimed in  claim 1 , wherein crystallization of alkali metal bicarbonate particles is carried out by concomitant cooling and carbonation of the solution; or by concomitant cooling and carbonation and evaporation of the solution. 
     
     
         9 . The method as claimed in  claim 1 , being carried out at a temperature between 20° C. and 95° C. 
     
     
         10 . The method as claimed in  claim 1 , wherein the additive is selected from alkyl ether sulfates. 
     
     
         11 . The method as claimed in  claim 1 , wherein the additive is isopropylamine dodecylbenzene sulfonate. 
     
     
         12 . The method as claimed in  claim 1 , wherein the additive is a polyether or ether-phenol selected from the group consisting of the following compounds:
 polyethylene glycol mono(tristyrylphenyl) ether;   ethoxylated oleyl alcohols;   branched octylphenoxy poly(ethyleneoxy)ethanols;   ethoxylated polyarylphenols.   
     
     
         13 . The method as claimed in  claim 1 , wherein the additive is sodium docusate as a sulfosuccinate. 
     
     
         14 . The method as claimed in  claim 1 , wherein the additive is an aminosulfonate selected from the group consisting of N-methyltaurine, sodium N-methyltaurinate, and isopropylamine dodecylbenzene sulfonate. 
     
     
         15 . The method as claimed in  claim 1 , wherein the additive is an organophosphate or phosphonate selected from the group consisting of the following compounds:
 polyoxyethylene alkylether phosphates, whose alkyl chain comprises from 6 to 20 carbons;   poly(oxy-1,2-ethanediyl),.alpha.-(dinonylphenyl)-omega-hydroxy-phosphate;   alkyl-phosphonic or hydroxyalkyl-phosphonic acids of semi-structural formula ((HO) 2 OP)—R with R being an alkyl group or hydroxyalkyl group, or salts thereof;   alkyl-diphosphonic acids of semi-structural formula ((HO) 2 OP)—R—(PO(OH) 2 ) with R being an alkyl group or a hydroxyalkyl group, or salts thereof;   nitrilo-alkyl-phosphonic acids of semi-structural formula ((HO) 2 OP—R) 3 —N with R being an alkyl chain with 1 to 5 carbons, or salts thereof.   
     
     
         16 . The method as claimed in  claim 1 , wherein addition of the additive is carried out for controlling or modifying:
 the undersize or oversize on a sieve at 125 μm, of the alkali metal bicarbonate particles obtained after separation of the crystallization solution and of the alkali bicarbonate particles.   
     
     
         17 . The method as claimed in  claim 1 , wherein addition of the additive is carried out for controlling or modifying:
 the bulk density (BD),   of the alkali metal bicarbonate particles obtained after separation of the crystallization solution and of the alkali bicarbonate particles, then drying of the alkali metal bicarbonate particles.   
     
     
         18 . Alkali metal bicarbonate particles obtainable by the method as claimed in  claim 1  and comprising at least 10 ppm of the additive.