Process for the production of sodium bicarbonate from diaphram cell liquors
AssigneeRhone-Poulenc Industries
InventorsAndre Artur, Charles Meniere
Life of this patent
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Abstract
Process and apparatus for producing bicarbonates by converting sodium hydroxide to sodium carbonate and reacting the sodium carbonate with carbon dioxide in a gas-liquid exchange and solid discharge zone and then in a gas-liquid exchange and solid discharge zone with cooling means, with possible recirculation, whereby bicarbonate is formed and precipitated in the first zone and bicarbonate formation is completed and precipitated in the second zone.
Claims8
A continuous method for obtaining sodium bicarbonate as crystals of a size to enable easy separation by filtration by the treatment with CO.sub.2 of sodium chloride electrolysis diaphragm cell liquor containing sodium hydroxide and sodium chloride, comprising:
- in a first zone treating the cell liquor with a carbon dioxide containing gas in an amount to convert sodium hydroxide to a neutral sodium carbonate which remains in solution;
- in a second zone subjecting the solution from the first zone to the action of a carbon dioxide containing gas to precipitate a portion of the sodium carbonate as sodium bicarbonate while maintaining the maximum temperature in said second zone below 70.degree. C.;
- passing the suspension obtained from the second zone to a third zone whereby bicarbonation is completed by the action of a carbon dioxide containing gas, and cooling the suspension to a final temperature of no more than 45.degree. C.;
- and
- finally separating the precipitated sodium bicarbonate, which includes the step of recycling a part of the suspension from the third zone back into the second zone.
A continuous method for obtaining sodium bicarbonate as crystals of a size to enable easy separation by filtration by the treatment with CO.sub.2 of sodium chloride electrolysis diaphragm cell liquor containing sodium hydroxide and sodium chloride, comprising:
- in a first zone treating the cell liquor with a carbon dioxide containing gas in an amount to convert sodium hydroxide to a neutral sodium carbonate which remains in solution;
- in a second zone subjecting the solution from the first zone to the action of a carbon dioxide containing gas to precipitate a portion of the sodium carbonate as sodium bicarbonate while maintaining the maximum temperature in said second zone below 70.degree. C.;
- passing the suspension obtained from the second zone to a third zone whereby bicarbonation is completed by the action of a carbon dioxide containing gas, and cooling the suspension to a final temperature of no more than 45.degree. C.;
- and
- finally separating the precipitated sodium bicarbonate which includes the step in which a portion of the suspension from the third zone is recycled to the head of the second zone.
A continuous method for obtaining sodium bicarbonate as crystals of a size to enable easy separation by filtration by the treatment with CO.sub.2 of sodium chloride electrolysis diaphragm cell liquor containing sodium hydroxide and sodium chloride, comprising:
- in a first zone treating the cell liquor with a carbon dioxide containing gas in an amount to convert sodium hydroxide to a neutral sodium carbonate which remains in solution;
- in a second zone subjecting the solution from the first zone to the action of a carbon dioxide containing gas to precipitate a portion of the sodium carbonate as sodium bicarbonate while maintaining the maximum temperature in said second zone below 70.degree. C.;
- passing the suspension obtained from the second zone to a third zone whereby bicarbonation is completed by the action of a carbon dioxide containing gas, and cooling the suspension to a final temperature of no more than 45.degree. C.;
- and
- finally separating the precipitated sodium bicarbonate, which includes the step of recycling mother liquor resulting from the separation of the sodium bicarbonate from the effluent of the third zone to the head end portion of the second zone.
A continuous method for obtaining sodium bicarbonate as crystals of a size to enable easy separation by filtration by the treatment with CO.sub.2 of sodium chloride electrolysis diaphragm cell liquor containing sodium hydroxide and sodium chloride, comprising:
- in a first zone treating the cell liquor with a carbon dioxide containing gas in an amount to convert sodium hydroxide to a neutral sodium carbonate which remains in solution;
- in a second zone subjecting the solution from the first zone to the action of a carbon dioxide containing gas to precipitate a portion of the sodium carbonate as sodium bicarbonate while maintaining the maximum temperature in said second zone below 70.degree. C.;
- passing the suspension obtained from the second zone to a third zone whereby bicarbonation is completed by the action of a carbon dioxide containing gas, and cooling the suspension to a final temperature of no more than 45.degree. C.;
- and
- finally separating the precipitated sodium bicarbonate, which includes the step of recycling part of the suspension from the head of the third zone to the head of the second zone.
Dependencies are inferred from the claim text.