Claims As on 10 October 2019
We Claim:
1. A method for preparing, by crystallization, alkali metal bicarbonate particles
starting from a solution of alkali metal carbonate and/or bicarbonate (solution
designated hereunder: 'the solution') in the presence of an additive in the
solution, characterized in that:
- the additive is selected from the following compounds:
• amines, in particular primary amines, cyclic amines, quaternary amines comprising at least one carboxylic acid group and hydroxysultaines;
• sulfates, in particular sodium sulfate and organosulfates;
• sulfonates;
• polysulfonates;
• polycarboxylates;
• polyethers and ether-phenols;
• sulfosuccinates;
• amidosulfonates;
• aminosulfonates;
• alkali metal hexametaphosphate in particular of sodium or potassium;
• phosphates, in particular organophosphates, and phosphonates;
- and the additive is present in the solution at a concentration of at least 1 ppm, advantageously at least 5 ppm, more advantageously at least 10 ppm.
2. The method as claimed in claim 1, in which the additive is an amine selected from hexamethylenediamine, hydroxysultaines and quaternary amines comprising at least one carboxylic acid group.
3. The method as claimed in claim 2, in which the amine is selected from quaternary amines comprising at least one carboxylic acid group.
4. The method as claimed in claim 2, in which the additive is selected from

• quaternary amines of formula: (H3C)3-N-R-COOH with R = (CH2)n and n = 1 to 4;
• cocamidopropyl hydroxysultaine.
5. The method as claimed in claim 2, in which the additive is trimetylglycine or hexamethylenediamine.
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Claims As on 10 October 2019
6. The method as claimed in any one of claims 2 to 5, in which the additive is present at a concentration of at most 200 ppm, advantageously at most 100 ppm, more advantageously at most 70 ppm.
7. The method as claimed in any one of claims 2 to 6, in which crystallization of alkali metal bicarbonate particles is carried out by cooling the solution.
8. The method as claimed in claim 7, in which cooling of the solution is carried out between 70° and 30°C.
9. The method as claimed in any one of claims 2 to 8, in which crystallization of alkali metal bicarbonate particles is carried out by carbonation of the solution with carbon dioxide.
10. The method as claimed in claim 9, in which carbonation of the solution is carried out at a temperature of at least 20°C, advantageously at least 30°C, and preferably at most 95°C, more preferably at most 90°C.
11. The method as claimed in any one of claims 2 to 10, in which crystallization of alkali metal bicarbonate particles is carried out by evaporation of at least a proportion of the solution.
12. The method as claimed in any one of claims 2 to 11, in which 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.
13. The method as claimed in any one of claims 9, 10 or 12, in which carbonation of the solution with carbon dioxide is carried out with a gas comprising: 10 to 100% of CO2 by volume based on dry gas, advantageously at least 20% of CO2 by volume based on dry gas, more advantageously at least 30% of CO2 by volume based on dry gas, even more advantageously at least 35% of CO2 by volume based on dry gas.
14. The method as claimed in any one of claims 2 to 13, carried out at a temperature between 20°C and 95°C, preferably between 30 and 90°C.
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Claims As on 10 October 2019
15. The method as claimed in any one of claims 2 to 14, in which addition of the
additive is carried out for controlling or modifying:
• the granulometry (such as D10, D50, D90 or the span), 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.
16. The method as claimed in any one of claims 2 to 15, in which addition of the
additive is carried out for controlling or modifying:
• the dissolution time, or
• the bulk density (BD), or
• the flow rate in a calibrated orifice,
• 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.
17. Alkali metal bicarbonate particles obtainable by the method as claimed in any
one of claims 1 to 16 and comprising at least 10 ppm, advantageously at least 20
ppm of the additive.
Dated this 10 day of October 2019
-Digitally Signed-(Rengasamy V) Reg. No: IN/PA-2051 Of De Penning & De Penning Agent for the Applicant
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