Method for preparing particles of alkali metal bicarbonate

Patent metadata

Field	Value
Publication number	US-2016145115-A1
Application number	US-201414900533-A
Country	US
Kind code	A1
Filing date	Jun 26, 2014
Priority date	Jun 26, 2013
Publication date	May 26, 2016
Grant date	—

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 amines, the hydroxysultaines, the polycarboxylates, the polysaccharides, the polyethers and the ether-phenols, alkali metal hexametaphosphate, the phosphates, the sulfosuccinates, the amidosulfonates, the aminosulfonates, preferably selected from the polycarboxylates having a mean molecular weight lower than 8000 g/mol, 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.

First claim

1 . 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 following compounds:
sulfates, in particular sodium sulfate and organosulfates;
sulfonates;
polysulfonates;
amines, in particular primary amines, cyclic amines, quaternary amines comprising at least one carboxylic acid group;
hydroxysultaines;
polysaccharides;
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.

2 . 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 a polycarboxylate; and wherein the additive is present in the solution at a concentration of at least 1 ppm.

3 . The method as claimed in claim 2 , wherein the additive is a polycarboxylate selected from the following compounds: polyacrylates, or copolymers of acrylic and maleic acids, or of sodium prop-2-enoate; and wherein the additive has an average molecular weight below 8000 g/mol.

4 . The method as claimed in claim 3 , wherein the additive is present at a concentration of at most 200 ppm.

5 . The method as claimed in claim 3 , wherein crystallization of alkali metal bicarbonate particles is carried out by cooling the solution.

6 . The method as claimed in claim 5 , wherein cooling of the solution is carried out between 70° and 30° C.

7 . The method as claimed in claim 3 , wherein crystallization of alkali metal bicarbonate particles is carried out by carbonation of the solution with carbon dioxide.

8 . The method as claimed in claim 7 , wherein carbonation of the solution is carried out at a temperature of at least 20° C.

9 . The method as claimed in claim 3 , wherein crystallization of alkali metal bicarbonate particles is carried out by evaporation of at least a proportion of the solution.

10 . The method as claimed in claim 3 , 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.

11 . The method as claimed in claim 7 , wherein carbonation of the solution with carbon dioxide is carried out with a gas comprising: 10 to 100% of CO 2 by volume based on dry gas.

12 . The method as claimed in claim 3 , being carried out at a temperature between 20° C. and 95° C.

13 . The method as claimed in claim 3 , wherein addition of the additive to the solution is carried out for controlling or modifying:
the granulometry 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.

14 . The method as claimed in claim 3 , 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.

15 . The method as claimed in claim 5 , wherein addition of the additive to the solution makes it possible to:
reduce the fraction of sieve oversize at 250 μm, or reduce the bulk density (BD)
of the alkali metal bicarbonate particles relative to one and the same preparation effected without the additive.

16 . The method as claimed in claim 7 , wherein the additive is present at a concentration of at most 200 ppm, and wherein addition of the additive to the solution makes it possible to:
reduce the granulometry or increase the span, or increase the sieve undersize at 125 μm, or reduce the dissolution time, or reduce the bulk density (BD), or increase the abrasion index,
of the alkali metal bicarbonate particles relative to one and the same preparation effected without the additive.

17 . The method as claimed in claim 7 , wherein the additive is present at a concentration of about 500 ppm, and wherein addition of the additive to the solution makes it possible to:
reduce the granulometry, or increase the span, or increase the sieve undersize at 125 μm, or increase the dissolution time, or reduce the bulk density (BD),
of the alkali metal bicarbonate particles relative to one and the same preparation effected without the additive.

18 . Alkali metal bicarbonate particles obtainable by the method as claimed in claim 2 and comprising at least 10 ppm of the additive.

Assignees

• Solvay

Inventors

• Savary David Jean Lucien

Classifications

• C01P2004/02

  obtained by optical microscopy · CPC title

• C01D7/40 Primary

  Influencing the crystallisation process · CPC title

• C01P2006/11

  Powder tap density · CPC title

• C01D7/00

  Carbonates of sodium, potassium or alkali metals in general · CPC title

• C01P2004/51

  Particles with a specific particle size distribution · CPC title