Chemistry: electrical and wave energy – Processes and products
Patent
1994-04-22
1995-12-26
Niebling, John
Chemistry: electrical and wave energy
Processes and products
423179, 4234994, 4234995, C01D 314, C01D 316, B01D 5334
Patent
active
054784476
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a process for the manufacture of aqueous sodium chloride solutions which can be employed in industrial processes.
TECHNOLOGY REVIEW
Aqueous sodium chloride solutions find important applications in industry. This is the case in particular in the industry for the manufacture of sodium carbonate by the ammonia-soda process, and in the processes for electrolytic manufacture of chlorine and of aqueous sodium hydroxide solutions.
These industrial processes generally require aqueous sodium chloride solutions of high purity, especially in respect of polyvalent metals such as, for example, calcium, magnesium, aluminium, iron, lead and zinc. This requirement is particularly strict in the case of electrolytic processes using membranes which are selectively permeable to cations, such as perfluorinated polymer membranes containing functional groups derived from carboxylic acid (GB-A-1,375,126). In these electrolytic processes sodium chloride solutions are generally recommended in which the polyvalent cation content, especially of calcium cations, does not exceed 0.1 ppm (GB-A-2,005,723).
The aqueous solutions intended for the electrolysis cells are generally obtained by dissolving rock salt in water (Chlorine, Its manufacture, Properties and Uses--J. S. Sconce--Reinhold Publishing Corporation, New York--1962--pages 119 and 123). However, the raw brines obtained by dissolving rock salt in water generally have a polyvalent cation content which is too high to permit their use in the electrolytic processes. It has been proposed, for this purpose, to treat them on chelating resins of the Na type, with the aim of extracting the polyvalent cations therefrom. (The American Institute of Chemical Engineers, No. 219, vol. 78, 1982, pages 46-53 :J. J. Wolff and R. E. Anderson, Ion-exchange purification of feed brine for chlor-alkali electrolysis cells; the role of Duolite ES-467).
Furthermore, there is a known process for purifying a smoke containing hydrogen chloride, according to which this smoke is treated with sodium bicarbonate so as to decompose the hydrogen chloride and to form sodium chloride (U.S. Pat. No. 4,767,605; SOLVAY & Cie, brochure Tr. 895/5c-B-1-1290). According to this known process sodium bicarbonate in powder form is introduced into the smoke to be purified and a solid residue containing sodium chloride is separated from the latter. When the smoke which is treated contains heavy metals, as is generally the case with smokes produced by the incineration of domestic or municipal waste, the solid sodium chloride residue is contaminated with these heavy metals, which thus cause difficulties in the storage or dumping of this residue.
The invention is aimed at providing a process which makes it possible to recover the solid sodium chloride residue from the known process described above, to manufacture an aqueous sodium chloride solution which can be employed in industrial processes.
SUMMARY OF THE INVENTION
Consequently, the invention relates to a process for the manufacture of an industrial aqueous solution of sodium chloride, according to which an aqueous medium comprising an aqueous solution of sodium chloride and of polyvalent metals is prepared and the said aqueous medium is treated to remove the polyvalent metals therefrom; according to the invention, in order to prepare the aqueous medium , a solid product collected from the dry-route treatment, with sodium bicarbonate, of a smoke containing hydrogen chloride and polyvalent metals is introduced into water.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a schematic diagram of a plant using a particular embodiment of the invention. FIGS. 2, 3, and 4 are also schematic diagrams illustrating three other embodiments of the invention. Each of these embodiments is described below.
DETAILED DESCRIPTION OF THE INVENTION
In the process according to the invention an industrial aqueous solution of sodium chloride is intended to denote an aqueous sodium chloride solution which is intended to be involved in the te
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Ian F. White et al.: "Secondary Brine Treatment: Ion-Exchange Purification of Brine". pp. 271-289 (no date).
Dale W. Kaufmann "Sodium Chloride--The Production and Properties of Salt and Brine". Reinhold Publishing Corporation, New York. 1960, pp. 204-275. (no month).
J. J. Wolff et al.: "Ion-exchange Purification of feed brine for chlor-alkali electrolysis cells; the role of Duolite ES-467." The American Institute of Chemical Engineers, No. 219, vol. 78, 1982, pp. 46-53 (no month).
J. S. Sconce: "Chlorine--Its Manufacture, Properties and Uses". Reinhold Publishing Corporation, New York, 1962, pp. 119-199 (no month).
"Sodium bicarbonate Purification of flue gases" Solvay & Cie, brochure Tr. 895/5c-B-1-1290 (no date).
Wolff et al. "Ion Exchange Purification of Feed Brine For Chlor-Alkali Electrolysis cell": the Role of Duolite .RTM.ES-46 (1982) pp. 46-53 no month.
Adam Jean-Francois
Humblot Cedric
Ninane Leon
Niebling John
Phasge Arun S,.
Solvay ( Societe Anonyme)
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