Method for preparing particles of alkali metal bicarbonate
AssigneeSolvay SA
InventorDavid Jean Lucien SAVARY
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Abstract
A method for preparing particles of alkali metal bicarbonate by crystallization from a solution of alkali metal carbonate and/or bicarbonate in the presence of an additive in the solution, selected from the sulfates, sulfonates, the polysulfonates, the mines, the hydroxysultaines, the polycarboxylates, the polysaccharides, the polyethers and the etherphenols, alkali metal hexametaphosphate, the phosphates such as the organophosphates or the phosphonates, the sulfosuccinates, the amido-sulfonates, the aminosulfonates, preferably selected from: the phosphates, the organophosphates or the phosphonates, and such that the additive is present in the solution at a concentration of at least 1 ppm and preferably of at most 200 ppm.
Claims26
A method for preparing, by crystallization, 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 group consisting of:
- sulfates, in particular sodium sulfate and organosulfates;
- sulfonates;
- polysulfonates;
- hydroxysultaines;
- polycarboxylates;
- polysaccharides;
- polyethers and ether-phenols;
- sulfosuccinates;
- amidosulfonates;
- aminosulfonates;
- alkali metal hexametaphosphate in particular of sodium or potassium;
- and
- phosphates, in particular organophosphates, and phosphonates;
- and the additive is present in the solution at a concentration of at least 1 ppm.
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The method as claimed in claim 20, wherein the additive is present at a concentration of at most 200 ppm.
The method as claimed in claim 20, wherein crystallization of the alkali metal bicarbonate particles is carried out by cooling the solution.
The method as claimed in claim 20, wherein crystallization of the alkali metal bicarbonate particles is carried out by carbonation of the solution with carbon dioxide.
The method as claimed in claim 20, wherein crystallization of the alkali metal bicarbonate particles is carried out by evaporation of at least a proportion of the solution.
The method as claimed in claim 20, wherein crystallization of the 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.
The method as claimed in claim 20, being carried out at a temperature between 20° C. and 95° C.
The method as claimed in claim 20, wherein addition of the additive to the solution is carried out for controlling or modifying:
- the granulometry, or
- the undersize or oversize on a sieve at 125 μm, or
- the undersize or oversize on a sieve at 250 μm,
- of the alkali metal bicarbonate particles obtained after separation of the crystallization solution and of the alkali bicarbonate particles.
The method as claimed in claim 20, wherein addition of the additive to the solution is carried out for controlling or modifying:
- the dissolution time, or
- the bulk density (BD), or
- the flow rate in a calibrated orifice, or
- the abrasion index,
- 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.
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Alkali metal bicarbonate particles obtainable by the method as claimed in claim 20 and comprising at least 10 ppm of the additive.
A method for preparing, by crystallization, alkali metal bicarbonate particles starting from a solution of alkali metal carbonate and/or in the presence of an additive in the solution,
- wherein the additive is an amine, and
- wherein the additive is present in the solution at a concentration of at least 1 ppm.
Dependencies are inferred from the claim text.