CA2009616A1 - Method of producing carbonic acid salts of alkali metals - Google Patents
Method of producing carbonic acid salts of alkali metalsInfo
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- CA2009616A1 CA2009616A1 CA002009616A CA2009616A CA2009616A1 CA 2009616 A1 CA2009616 A1 CA 2009616A1 CA 002009616 A CA002009616 A CA 002009616A CA 2009616 A CA2009616 A CA 2009616A CA 2009616 A1 CA2009616 A1 CA 2009616A1
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- Prior art keywords
- alkali metal
- cell
- solution
- aqueous
- metal salt
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D7/00—Carbonates of sodium, potassium or alkali metals in general
- C01D7/07—Preparation from the hydroxides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
- B01D61/44—Ion-selective electrodialysis
- B01D61/445—Ion-selective electrodialysis with bipolar membranes; Water splitting
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
Abstract
Abstract An energy-saving, environmentally safe process for producing alkali carbonates by electrodialysis of alkali salts and carbonation of the resulting alkali hydroxide solution.
Description
;~009616 METHOD OF PRODUCING CARBONIC ACID
SALTS OF ALKALI METALS
Back~round of the Invention ~ he present invention relates to a method for the production of carbonic acid salts of alkali metals from aqueous solutions of an alkali metal salt by obtaining a high-purity aqueous solution of the alkali metal hydroxide and then carbonating this alkali metal hydroxide solution.
The known carbonic acid salts of the alkali metals are used in various technical fields.
Lithium carbonate serves, for example, for making glazes on porcelain.
Sodium carbonate, for example, is the technically most important sodium compound after sodium chloride, and it is widely needed in glass making and water softening, among other things, for the chemical industry for example. In addition, it serves as a reagent in analytical chemistry and as an adjuvant in pharmacology.
Sodium hydrogen carbonate is found, for example, in fire extinguishers. It also is used in the food industry as a baking aid or for producing carbonated beverages.
Potassium carbonate is needed industrially, for example, in the manufacture of glass and of soap, and in liquid shampoos.
Potassium hydrogen carbonate is used for the production of foods, as a baking aid, for example, and in substances for controlling the electrolyte balance, in athletes, for example.
A variety of methods have been developed for producing carbonic acid salts of the alkali metals.
Lithium carbonate is obtained, for example, by reacting lithium salts and carbonates, especially sodium or potassium carbonate, and by the carbonation of lithium hydroxide.
Sodium carbonate can be obtained in impure form from natural deposits, e.g., from Egyptian or American salt lakes. The Solvay process represents a large-scale manufacturing method for sodium carbonate, which starts from sodium chloride, ammonia and carbon dioxide. The soda obtained in this way has a purity of about 98%.
Sodium hydrogen carbonate and potassium hydrogen carbonate (the existence of lithium hydrogen carbonate is disputed) are prepared from the corresponding hydroxides or carbonates by contact with excess carbon dioxide (supercarbonation).
According to the state of the art, high-purity carbonic acid salts of alkali metals, such as those used in the food industry and pharmacology, are obtained by carbonating the corresponding alkali hydroxide solution, which has been prepared by electrolysis via the mercury process. If, for example, a direct electrical current is passed through an aqueous alkali chloride solution, chlorine gas is principally formed at the positive pole, or anode. At the negative pole, or cathode, hydrogen gas and alkali hydroxide form. To prevent the products from mixing, mercury is used as the cathode in a particular embodiment of that process.
The alkali metal primarily formed at the cathode dissolves in mercury (amalgamation) and can be reacted with water in an additional process step to high-purity alkali hydroxide.
The mercury process, therefore, is a modified electrolysis process. The decisive advantage of the mercury process--the high purity of the resulting alkali lye--is offset, however, by the disadvantage that small amounts of mercury 2~09616 are continuously lost from the electrolysis cells. These mercury losses are composed of the amounts of mercury that remain in the product (about 1 to 10 ppm in the hydroxide solution), and the amounts of mercury carried off with the exhaust air and filter sludges. Consequently, careful and expensive purification of the products, the exhaust air, the waste water and the reaction residues is necessary in order to prevent mercury emissions.
Carbonic acid alkali salts prepared by other methods can be obtained in pure form only after complex purification operations.
Summary of the Invention It is the object of the invention to provide a method of preparing high-purity carbonic acid salts of the alkali metals which will avoid the disadvantages of the previously known methods.
These and other objects of the invention are achieved by providing a method of producing a carbonic acid salt of an alkali metal from an aqueous inorganic alkali metal salt solution in which the aqueous alkali metal salt solution is converted to an alkali metal hydroxide solution and subsequently carbonated, comprising the steps of:
a) providing an electrodialyzer comprising an anode, a cathode, and at least one dialysis unit subdivided into:
- a cell X arranged toward said anode and bounded on its side oriented toward said anode by a cation-selective layer of a bipolar membrane, - a cell Z arranged toward said cathode and bounded on its side oriented toward said cathode by an anion-selective layer of a bipolar membrane, and - a middle cell Y arranged between cells X and Z, and separated from cell X by an anion-selective membrane and from cell Z by a cation-selective membrane, and 2()C~616 subjecting the alkali metal salt solution to electrodialysis in said electrodialyzer by:
- introducing an aqueous inorganic alkali metal salt solution as a feed stream into cell Y, a substantially salt-free aqueous solution of the acid corresponding to thealkali metal salt as a feed stream into cell X, and a substantially salt-free aaueous solution of the alkali metal hydroxide corresponding to the alkali metal salt as a feed stream into cell Z;
- passing electric current through the electrodialyzer by applying a direct current voltage across said anode and cathode; and - collecting a depleted alkali metal salt solution as a product stream from cell Y, an enriched aqueous solution of the inorganic acid corresponding to the alkali metal salt from cell X, and an enriched solution of the alkali metal hydroxide corresponding to the alkali metal salt as a product stream from cell Z; and b) introducing the alkali metal hydroxide solution collected in step a) to a carbonator and mixing it with a reagent selected from the group consisting of gaseous carbon dioxide and a solution of the hydrogen carbonate of the alkali metal, for carbonation to form a carbonic acid salt of the alkali metal; and c) recovering the carbonic acid salt of the alkali metal formed in step b).
Brief Description of the Drawings The invention will be explained in further detail with reference to the accompanying drawings in which:
Fig. 1 is a schematic representation of an electrodialyzer suitable for carrying out the method of the invention; and Fig. 2 is a schematic flow diagram of a preferred system according to the invention for carrying out a preferred embodiment of the method of the invention.
2~(~96~6 Detailed Description of Preferred Embodiments The method according to the invention for producing carbonic acid salts of alkali metals from aqueous inorganic alkali metal salt solutions by converting the aqueous alkali metal salt solutions to an alkali metal hydroxide solution, and then carbonating the latter, is characterized by the following steps:
a) subiecting the alkali metal salt solution to an electrodialysis in an electrodialyzer in which at least one dialysis unit defined at the sides facing the electrodes by bipolar or cation-selective membranes and divided into three cells X, Y and Z, in which dialysis unit the middle cell Y is separated from cell X facing the anode by an anion-selective membrane and from cell Z facing the cathode by a cation-selective membrane, and cell X is bounded on the side facing the anode electrode by the cation-selective layer of the bipolar membrane, and cell Z is bounded on the side facing the cathode by the anion-selective layer of the bipolar membrane, by introducing the aqueous inorganic alkali metal salt solution as feed stream into cell Y, introducing a substantially salt-free aqueous solution of the acid corresponding to the alkali metal salt as a feed stream into cell X, and introducing a substantially salt-free aqueous solution of the alkali metal hydroxide corresponding to the alkali metal salt as feed stream into cell Z, passing electric current through the electrodialyzer by applying a direct-current voltage, and withdrawing a depleted alkali metal salt solution as a product stream from cell Y, withdrawing an enriched aqueous solution of the inorganic acid corresponding to the alkali metal salt from cell X, and withdrawing an enriched solution of the alkali metal hydroxide corresponding to the alkali metal salt as a product stream from cell Z, and b) introducing the alkali metal hydroxide solution obtained in step a) to a carbonator and mixing it with a reagent selected from the group consisting of gaseous carbon dioxide and/or a solution of the hydrogen 5carbonate of the alkali metal for carbonation to form the carbonic acid salts of the alkali metal, and c) recovering the carbonic acid salts of the alkali metal formed in step b).
10Any water-soluble inorganic salts of the alkali metal in question can be used in the method of the invention.
Suitable acid anions include the anions of the oxo acids of the elements of Group V of the periodic table, particularly nitrate, phosphate, hydrogen phosphate and dihydrogen phosphate; the anions of the oxo acids of elements of the Group VI of the periodic table with the exception of oxygen, in various degrees of oxidation, particularly the sulfate anion and the hydrogen sulfate anion; the halide anions, and the anions of the oxo acids of the halogens in various degrees of oxidation.
The halide anions are preferably used. The chlorides are especially preferred.
In the method of the invention, an aqueous solution of a potassium salt, particularly of potassium chloride, is used as the aqueous inorganic alkali metal salt solution.
Known electrodialyzers can be used in the method of the invention. The manner of operation of an electrodialyzer that can be used in the method of the invention is illustrated by Figure 1. The dialyzer 1 comprises a cathode chamber 5 and an anode chamber 6, and one or more, for example up to several hundred, intermediately positioned dialysis separator units.
One electrodialysis separation unit comprises three cells, X, Y and Z. Cell Y is separated from cell X by a membrane A which is selectively permeable to anions ("anion-205:~9616 selective"), and separated from cell Z by a membrane K whichis selectively permeable to cations ("cation-selective").
Cell X is separated from the anode chamber on its side facing the anode either by a bipolar or cation-selective membrane, or from cell Z of an ad~oining additional separator unit by a bipolar membrane AK, whereby the cation-selective side of the membrane faces cell X.
Cell Z is also separated from the cathode chamber or from cell X of an adjacent separator unit, on its side facing the cathode, by a bipolar membrane AK. The anion-selective side of this membrane faces cell Z. Instead of the bipolar membrane, cell Z can be omitted from the final dialysis unit in the direction of the cathode, and the dialysis unit can terminate directly at the cathode with the cation-selective membrane of the side of cell Y facing the cathode.
Now, if an aqueous alkali metal salt solution is supplied through line 2 to cell Y, a substantially salt-free aqueous acid solution is supplied to cell X through line 3, and substantially salt-free aqueous alkali hydroxide solution is supplied to cell Z through line 4, and a direct current voltage, for example 0.5 to 4 volts per dialysis separator unit, is applied across the electrodes, then anions will migrate ~rom cell Y into cell X, and cations from cell Y into cell Z. The compensation of the charges is effected in the case of cell X by protons which are formed in the bipolar membrane AK from water diffused into it and which migrate through the cation-selective side of the membrane into cell X. In the case of cell Z, the compensation of the charges is effected by hydroxyl anions which are formed in the bipolar membrane AK from water diffused into it, and which can pass through the anion-selective side of the polar membrane into cell Z. Hydrogen evolves at the cathode and oxygen at the anode.
The electrodialysis thus produces in cell Y a solution depleted of alkali metal salt, in X an enriched aqueous Z0C~96~6 solution of an acid, and in cell Z an enriched aqueous solution of an alkali hydroxide, which are withdrawn from the electrodialysis apparatus through lines 7, 8 and 9, respectively.
The electrodialysis is carried out at temperatures above the freezing point of the solutions up to about 60C, preferably between about 35C and 50C.
An aqueous solution of an acid corresponding to the alkali salt is supplied as a feed stream to cell X. Its acid content can be within a wide range, for example from 0.1 to about 30 wt% and more, and depends substantially on the acid that is used. In the case of hydrochloric acid, the concentration may range from 0.5 to 32 wt%, and in the case of sulfuric acid from 0.5 to 60 wt%. Preferably the acid content is between about 1 to 10 wt%, particularly between about 3 to 5 wt%.
An aqueous solution of an alkali metal salt, whose alkali metal salt content can vary within a wide range, e.g., from about 0.5 wt% all the way to a saturated solution, is introduced into cell Y. Preferably solutions are used which contain the alkali metal salt in an amount corresponding to about 50 to 100% of saturation. Saturated solutions are especially preferred.
The depleted alkali metal salt solution obtained as product stream from cell Y is preferably not discarded but resaturated by addition of alkali metal salt and returned as a feed stream to cell Y.
An aqueous solution of an alkali hydroxide corresponding to the alkali metal salt is supplied as a feed stream to cell Z. The alkali hydroxide content of this stream may vary over a wide range, for example between about 0.5 to about 50 wt%. Hydroxide contents from about 2 to about 25 wt% are preferred, especially hydroxide contents from about 12 to about 18 wt%.
In the course of the method of the invention, a salt solution depleted of alkali metal salt is obtained from cell Z0096~6 Y, while in cell X an aqueous solution enriched in acid is obtained and in cell Z an aqueous solution enriched in alkali hydroxide.
The acid of the product stream from cell X can be used, for example, entirely for producing carbon dioxide in a separate step. In a preferred embodiment, a portion of the acid-containing product stream, however, is diverted and returned to the feed stream of cell X. In this case, therefore, a portion of the acid is recycled.
A greater or lesser proportion of the acid content of the feed stream can be derived from recycled acid.
Preferably the entire acid content of the feed stream is derived from recycled acid, so that no acid has to be introduced into the process.
Naturally, it is also possible to collect the acid-containing product stream from the process, or part thereof if desired, and supply it to some other use, for example to prepare a pure, concentrated acid.
The aqueous solution of alkali metal hydroxide withdrawn from cell Z may all be fed to the carbonation. In a preferred embodiment, however, a portion of the product stream containing alkali metal hydroxide is recycled to the feed stream of cell Z. In this case a portion of the alkali metal hydroxide is recycled.
A greater or lesser proportion of the alkali metal hydroxide content of the feed stream can be derived from recycled hydroxide solution. Preferably all of the alkali metal hydroxide in the feed stream is derived from recycled solution, so that no alkali metal hydroxide has to be introduced into the process.
The concentrations of the acid in the product stream withdrawn from cell X, of the alkali metal hydroxide in the product stream withdrawn from cell Z, and of the alkali metal salt in the product stream withdrawn from cell Y, depend on the concentrations of the respective feed streams as well as on the reaction conditions of the 2oo96~6 electrodialysis, such as the capacity of the dialyzer, the residence times of the feed streams in the cells, the temperature, the voltage and the current.
Depending on the reaction conditions of the electrodialysis, the difference in concentration between the inlets and outlets of the cells may be larger or smaller.
Preferably the reaction conditions are selected such that the difference in concentration between the inlet and outlet of the cells is small, i.e., such that the concentration of the acid solution or alkali hydroxide solution withdrawn from the electrodialyzer is only slightly higher than the concentration of the acid solution or alkali hydroxide solution introduced into the electrodialyzer.
Advantageously, a large proportion of the product streams is thereby recirculated, and only a small portion is withdrawn. The difference can be compensated for by addition of water.
The feed streams to cells X and Z should be substantially salt-free. The expression, "substantially salt-free," as used in connection with the present invention, is to be understood to mean that, except for any slight contamination that may be present, no salts are present in solution. The alt content of the feed streams to cells X and Z should be, for example, less than about 0.1 wt%.
For the carbonation, the alkali metal hydroxide solution withdrawn from cell Z, after diverting a portion that is recycled to the feed stream, is introduced into a carbonator and mixed with gaseous CO2 and/or with solutions of the hydrogen carbonates of the particular alkali metal, so as to form the carbonic acid salts of the alkali metal.
The exhaust gas from a combustion process or from a lime kiln, for example, can be used as the carbon dioxide gas. It can also be obtained, however, by reacting carbonic acid salts, particularly CaC03, with an acid. The method of the present invention preferably makes use of carbon dioxide 2009~16 that has been released by the reaction of CaCO3 with the acid taken from cell X. Accordingly, in a preferred embodiment of the present invention, the enriched aqueous acld solution obtained as a product stream from cell X in step a), after diverting in some cases a portion to be recycled to the feed stream of cell X, is reacted at least partially wlth calcium carbonate, and the C02 gas that is formed is introduced into the carbonator in step b).
Within the scope of the invention, step b), i.e., the carbonation of the alkali metal hydroxide solution obtained in step a), and step c), i.e., the separation of the carbonic salts of the alkali metal which are obtained in stsp b), can be carried out in known manner. For example, a method is disclosed in German Patent No. DE 954 414 for the production of anhydrous, gritty alkali carbonate, the formation and isolation of the carbonate being performed in a single step. In this method, powdered or finely granular alkali carbonate is introduced into a fluidized-bed oven, fluidized with hot gases containing CO2, and alXali lye is sprayed into the fluidized bed. Due to the high temperature of the gases (about 300 to about 450C for the production of sodium carbonate, and about 250 to about 400C for the production of potassium carbonate), the resulting carbonates are anhydrous.
In the method of the invention, the carbonation of the alkali metal hydroxide solution and separation of the carbonic acid salts of the alkali metal can also be carried out separately from each other at different times and/or at different locations.
Step b), i.e., the carbonation, can be performed by contacting the alkali hydroxide solution collected from step a) with gases containing carbon dioxide in Gne or more stirring vessels or in one or more successively arranged perforated-tray or packed columns, or in spray towers.
201~9616 Step c), i.e., the separation of the carbonic aid salts of the alkali metal from the liquid flowing out of the carbonator, which contains the carbonic acid salts of the alkali metal in solution and, in some cases, in suspension, can be performed in a known manner. For example, if an aqueous suspension has been obtained from step b), it can first be concentrated in a concentrator or a centrifugal separator. Also, a solution or suspension obtained in step b) can be concentrated, e.g., by evaporating the water, with the aid of a vacuum if desired, or by treating the solution by ultrafiltration or reverse osmosis.
Also, the hydrogen carbonate salts of the alkali metals can be obtained by "supercarbonation," i.e., the reaction of alkali lye or alkali carbonate for example with cooled C02 gas in sprinkler towers. The resulting crystals can then be extracted by centrifugation and dried.
The process of the present invention has the following advantages:
- The method of the invention permits the energy-saving manufacture of pure alkali carbonates and alkali hydrogen carbonates from alkali salts and carbon dioxide without requiring the use of mercury.
- By-products are produced, such as inorganic acids and/or salt solutions, e.g., solutions of CaCl2, which due to their purity constitute valuable intermediate products.
- The method of the invention permits direct production of carbonic acid salts of alkali metals which can be used for pharmaceutical purposes and/or as additives in the food industry without complex purifying operations.
Without limiting the scope of the invention, the method of the invention will be described in further detail in the following example with reference to Figure 2, which represents a flow diagram of a preferred embodiment.
A commercially available apparatus with eight separator units, a voltage of 20 volts and a current of 10 amperes was used as the electrodialyzing apparatus 1. The basic method of operation of such a dialyzer has already been described with reference to Figure 1. The electro-dialysis was carried out at about 40c.
Through a conduit 2, an aqueous, saturated potassium chloride solution (potassium chloride content about 28% by weight), which also contained about 1000 ppm of magnesium chloride, was initially passed through a filter t0.1 mm mesh width) to remove any solids it might contain. The solution leaving the filter was introduced as a feed stream into cells Y.
An aqueous hydrochloric acid solution having a concentration of about 4 wt% HCl was introduced through a feed line 3 into cells X.
A potash lye having a concentration of about 15 wt% KOH
was introduced through a feed line 4 into cells Z.
The applied direct current of about 20 volts produced the transfer of Cl ions from the Y cells to the X cells and of K~ ions to the Z cells.
The volumetric flow rates of the feed streams were regulated such that an approximately 5% hydrochloric acid solution from the X cells, and an approximately 18% potash lye from the Z cells, were obtained as product streams. The KCl solution coming from cell Y was recycled after addition of fresh KCl up to the saturation point of about 28 wt%.
This saturated potassium chloride solution was then introduced as a feed stream through the filter and conduit 2 into cells Y.
The hydrochloric acid solution enriched to about 5 wt%
HCl was withdrawn from the X cells through conduit 8. A
portion of the product stream was diverted from conduit 8 through conduit 16 and mixed with water to obtain a hydrochloric acid solution of about 4 wt% HCl. This hydrochloric acid solution constituted the feed stream for 2009~6 the X cells. In this manner a portion of the hydrochloric acid solution was recycled.
A potash lye having a KOH content of about 18 wt~ was withdrawn from the Z cells. A portion of the product stream was diverted from conduit g through conduit 15 and mixed with water to obtain a potassium hydroxide solution having a concentration of about 15 wt% KOH. This solution constituted the feed stream for the Z cells. In this manner a portion of the potassium hydroxide solution was recycled.
The stream of hydrochloric acid solution that was not diverted for recycling was introduced into a lime dissolver 18 into which an amount of pulverized limestone corresponding to the amount of acid was continuously fed by a vibrating trough 17. The calcium chloride solution formed in the reaction between the aqueous hydrochloric acid solution and the limestone was withdrawn from the lime dissolver 18 through an overflow and carried away through a conduit 19, while the carbon dioxide gas formed in the reaction was injected into a carbonator 11 through line 10 from a water separator (not shown in Fig. 2).
At the same time the stream of potassium hydroxide solution that was not diverted for recycling was fed through line 9 into the carbonator 11. A conventional column was used as the carbonator. The suspension leaving the carbonator was concentrated and introduced into a crystallizer 12 and separated into solid material and a solution substantially free of solids. The solids were transferred to a dryer 13, dried there by hot air at a temperature of about 110 to 120C, and discharged from the dryer through the conduit 14. The resulting hydrated potash, corresponding to the formula K2CO3~1.5 H2O, had a purity of 99.1% and contained only 10 ppm of MgCl2. The yield amounted to about 85%, based on the amount of KCl used.
20096'~ 6 The foregoing description and examples have been set forth merely to illustrate the invention and are not intended to be limiting. Since modifications of the described embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the scope of the invention should be construed to include e~erything falling within the ambit of the appended claims and equivalents thereof.
SALTS OF ALKALI METALS
Back~round of the Invention ~ he present invention relates to a method for the production of carbonic acid salts of alkali metals from aqueous solutions of an alkali metal salt by obtaining a high-purity aqueous solution of the alkali metal hydroxide and then carbonating this alkali metal hydroxide solution.
The known carbonic acid salts of the alkali metals are used in various technical fields.
Lithium carbonate serves, for example, for making glazes on porcelain.
Sodium carbonate, for example, is the technically most important sodium compound after sodium chloride, and it is widely needed in glass making and water softening, among other things, for the chemical industry for example. In addition, it serves as a reagent in analytical chemistry and as an adjuvant in pharmacology.
Sodium hydrogen carbonate is found, for example, in fire extinguishers. It also is used in the food industry as a baking aid or for producing carbonated beverages.
Potassium carbonate is needed industrially, for example, in the manufacture of glass and of soap, and in liquid shampoos.
Potassium hydrogen carbonate is used for the production of foods, as a baking aid, for example, and in substances for controlling the electrolyte balance, in athletes, for example.
A variety of methods have been developed for producing carbonic acid salts of the alkali metals.
Lithium carbonate is obtained, for example, by reacting lithium salts and carbonates, especially sodium or potassium carbonate, and by the carbonation of lithium hydroxide.
Sodium carbonate can be obtained in impure form from natural deposits, e.g., from Egyptian or American salt lakes. The Solvay process represents a large-scale manufacturing method for sodium carbonate, which starts from sodium chloride, ammonia and carbon dioxide. The soda obtained in this way has a purity of about 98%.
Sodium hydrogen carbonate and potassium hydrogen carbonate (the existence of lithium hydrogen carbonate is disputed) are prepared from the corresponding hydroxides or carbonates by contact with excess carbon dioxide (supercarbonation).
According to the state of the art, high-purity carbonic acid salts of alkali metals, such as those used in the food industry and pharmacology, are obtained by carbonating the corresponding alkali hydroxide solution, which has been prepared by electrolysis via the mercury process. If, for example, a direct electrical current is passed through an aqueous alkali chloride solution, chlorine gas is principally formed at the positive pole, or anode. At the negative pole, or cathode, hydrogen gas and alkali hydroxide form. To prevent the products from mixing, mercury is used as the cathode in a particular embodiment of that process.
The alkali metal primarily formed at the cathode dissolves in mercury (amalgamation) and can be reacted with water in an additional process step to high-purity alkali hydroxide.
The mercury process, therefore, is a modified electrolysis process. The decisive advantage of the mercury process--the high purity of the resulting alkali lye--is offset, however, by the disadvantage that small amounts of mercury 2~09616 are continuously lost from the electrolysis cells. These mercury losses are composed of the amounts of mercury that remain in the product (about 1 to 10 ppm in the hydroxide solution), and the amounts of mercury carried off with the exhaust air and filter sludges. Consequently, careful and expensive purification of the products, the exhaust air, the waste water and the reaction residues is necessary in order to prevent mercury emissions.
Carbonic acid alkali salts prepared by other methods can be obtained in pure form only after complex purification operations.
Summary of the Invention It is the object of the invention to provide a method of preparing high-purity carbonic acid salts of the alkali metals which will avoid the disadvantages of the previously known methods.
These and other objects of the invention are achieved by providing a method of producing a carbonic acid salt of an alkali metal from an aqueous inorganic alkali metal salt solution in which the aqueous alkali metal salt solution is converted to an alkali metal hydroxide solution and subsequently carbonated, comprising the steps of:
a) providing an electrodialyzer comprising an anode, a cathode, and at least one dialysis unit subdivided into:
- a cell X arranged toward said anode and bounded on its side oriented toward said anode by a cation-selective layer of a bipolar membrane, - a cell Z arranged toward said cathode and bounded on its side oriented toward said cathode by an anion-selective layer of a bipolar membrane, and - a middle cell Y arranged between cells X and Z, and separated from cell X by an anion-selective membrane and from cell Z by a cation-selective membrane, and 2()C~616 subjecting the alkali metal salt solution to electrodialysis in said electrodialyzer by:
- introducing an aqueous inorganic alkali metal salt solution as a feed stream into cell Y, a substantially salt-free aqueous solution of the acid corresponding to thealkali metal salt as a feed stream into cell X, and a substantially salt-free aaueous solution of the alkali metal hydroxide corresponding to the alkali metal salt as a feed stream into cell Z;
- passing electric current through the electrodialyzer by applying a direct current voltage across said anode and cathode; and - collecting a depleted alkali metal salt solution as a product stream from cell Y, an enriched aqueous solution of the inorganic acid corresponding to the alkali metal salt from cell X, and an enriched solution of the alkali metal hydroxide corresponding to the alkali metal salt as a product stream from cell Z; and b) introducing the alkali metal hydroxide solution collected in step a) to a carbonator and mixing it with a reagent selected from the group consisting of gaseous carbon dioxide and a solution of the hydrogen carbonate of the alkali metal, for carbonation to form a carbonic acid salt of the alkali metal; and c) recovering the carbonic acid salt of the alkali metal formed in step b).
Brief Description of the Drawings The invention will be explained in further detail with reference to the accompanying drawings in which:
Fig. 1 is a schematic representation of an electrodialyzer suitable for carrying out the method of the invention; and Fig. 2 is a schematic flow diagram of a preferred system according to the invention for carrying out a preferred embodiment of the method of the invention.
2~(~96~6 Detailed Description of Preferred Embodiments The method according to the invention for producing carbonic acid salts of alkali metals from aqueous inorganic alkali metal salt solutions by converting the aqueous alkali metal salt solutions to an alkali metal hydroxide solution, and then carbonating the latter, is characterized by the following steps:
a) subiecting the alkali metal salt solution to an electrodialysis in an electrodialyzer in which at least one dialysis unit defined at the sides facing the electrodes by bipolar or cation-selective membranes and divided into three cells X, Y and Z, in which dialysis unit the middle cell Y is separated from cell X facing the anode by an anion-selective membrane and from cell Z facing the cathode by a cation-selective membrane, and cell X is bounded on the side facing the anode electrode by the cation-selective layer of the bipolar membrane, and cell Z is bounded on the side facing the cathode by the anion-selective layer of the bipolar membrane, by introducing the aqueous inorganic alkali metal salt solution as feed stream into cell Y, introducing a substantially salt-free aqueous solution of the acid corresponding to the alkali metal salt as a feed stream into cell X, and introducing a substantially salt-free aqueous solution of the alkali metal hydroxide corresponding to the alkali metal salt as feed stream into cell Z, passing electric current through the electrodialyzer by applying a direct-current voltage, and withdrawing a depleted alkali metal salt solution as a product stream from cell Y, withdrawing an enriched aqueous solution of the inorganic acid corresponding to the alkali metal salt from cell X, and withdrawing an enriched solution of the alkali metal hydroxide corresponding to the alkali metal salt as a product stream from cell Z, and b) introducing the alkali metal hydroxide solution obtained in step a) to a carbonator and mixing it with a reagent selected from the group consisting of gaseous carbon dioxide and/or a solution of the hydrogen 5carbonate of the alkali metal for carbonation to form the carbonic acid salts of the alkali metal, and c) recovering the carbonic acid salts of the alkali metal formed in step b).
10Any water-soluble inorganic salts of the alkali metal in question can be used in the method of the invention.
Suitable acid anions include the anions of the oxo acids of the elements of Group V of the periodic table, particularly nitrate, phosphate, hydrogen phosphate and dihydrogen phosphate; the anions of the oxo acids of elements of the Group VI of the periodic table with the exception of oxygen, in various degrees of oxidation, particularly the sulfate anion and the hydrogen sulfate anion; the halide anions, and the anions of the oxo acids of the halogens in various degrees of oxidation.
The halide anions are preferably used. The chlorides are especially preferred.
In the method of the invention, an aqueous solution of a potassium salt, particularly of potassium chloride, is used as the aqueous inorganic alkali metal salt solution.
Known electrodialyzers can be used in the method of the invention. The manner of operation of an electrodialyzer that can be used in the method of the invention is illustrated by Figure 1. The dialyzer 1 comprises a cathode chamber 5 and an anode chamber 6, and one or more, for example up to several hundred, intermediately positioned dialysis separator units.
One electrodialysis separation unit comprises three cells, X, Y and Z. Cell Y is separated from cell X by a membrane A which is selectively permeable to anions ("anion-205:~9616 selective"), and separated from cell Z by a membrane K whichis selectively permeable to cations ("cation-selective").
Cell X is separated from the anode chamber on its side facing the anode either by a bipolar or cation-selective membrane, or from cell Z of an ad~oining additional separator unit by a bipolar membrane AK, whereby the cation-selective side of the membrane faces cell X.
Cell Z is also separated from the cathode chamber or from cell X of an adjacent separator unit, on its side facing the cathode, by a bipolar membrane AK. The anion-selective side of this membrane faces cell Z. Instead of the bipolar membrane, cell Z can be omitted from the final dialysis unit in the direction of the cathode, and the dialysis unit can terminate directly at the cathode with the cation-selective membrane of the side of cell Y facing the cathode.
Now, if an aqueous alkali metal salt solution is supplied through line 2 to cell Y, a substantially salt-free aqueous acid solution is supplied to cell X through line 3, and substantially salt-free aqueous alkali hydroxide solution is supplied to cell Z through line 4, and a direct current voltage, for example 0.5 to 4 volts per dialysis separator unit, is applied across the electrodes, then anions will migrate ~rom cell Y into cell X, and cations from cell Y into cell Z. The compensation of the charges is effected in the case of cell X by protons which are formed in the bipolar membrane AK from water diffused into it and which migrate through the cation-selective side of the membrane into cell X. In the case of cell Z, the compensation of the charges is effected by hydroxyl anions which are formed in the bipolar membrane AK from water diffused into it, and which can pass through the anion-selective side of the polar membrane into cell Z. Hydrogen evolves at the cathode and oxygen at the anode.
The electrodialysis thus produces in cell Y a solution depleted of alkali metal salt, in X an enriched aqueous Z0C~96~6 solution of an acid, and in cell Z an enriched aqueous solution of an alkali hydroxide, which are withdrawn from the electrodialysis apparatus through lines 7, 8 and 9, respectively.
The electrodialysis is carried out at temperatures above the freezing point of the solutions up to about 60C, preferably between about 35C and 50C.
An aqueous solution of an acid corresponding to the alkali salt is supplied as a feed stream to cell X. Its acid content can be within a wide range, for example from 0.1 to about 30 wt% and more, and depends substantially on the acid that is used. In the case of hydrochloric acid, the concentration may range from 0.5 to 32 wt%, and in the case of sulfuric acid from 0.5 to 60 wt%. Preferably the acid content is between about 1 to 10 wt%, particularly between about 3 to 5 wt%.
An aqueous solution of an alkali metal salt, whose alkali metal salt content can vary within a wide range, e.g., from about 0.5 wt% all the way to a saturated solution, is introduced into cell Y. Preferably solutions are used which contain the alkali metal salt in an amount corresponding to about 50 to 100% of saturation. Saturated solutions are especially preferred.
The depleted alkali metal salt solution obtained as product stream from cell Y is preferably not discarded but resaturated by addition of alkali metal salt and returned as a feed stream to cell Y.
An aqueous solution of an alkali hydroxide corresponding to the alkali metal salt is supplied as a feed stream to cell Z. The alkali hydroxide content of this stream may vary over a wide range, for example between about 0.5 to about 50 wt%. Hydroxide contents from about 2 to about 25 wt% are preferred, especially hydroxide contents from about 12 to about 18 wt%.
In the course of the method of the invention, a salt solution depleted of alkali metal salt is obtained from cell Z0096~6 Y, while in cell X an aqueous solution enriched in acid is obtained and in cell Z an aqueous solution enriched in alkali hydroxide.
The acid of the product stream from cell X can be used, for example, entirely for producing carbon dioxide in a separate step. In a preferred embodiment, a portion of the acid-containing product stream, however, is diverted and returned to the feed stream of cell X. In this case, therefore, a portion of the acid is recycled.
A greater or lesser proportion of the acid content of the feed stream can be derived from recycled acid.
Preferably the entire acid content of the feed stream is derived from recycled acid, so that no acid has to be introduced into the process.
Naturally, it is also possible to collect the acid-containing product stream from the process, or part thereof if desired, and supply it to some other use, for example to prepare a pure, concentrated acid.
The aqueous solution of alkali metal hydroxide withdrawn from cell Z may all be fed to the carbonation. In a preferred embodiment, however, a portion of the product stream containing alkali metal hydroxide is recycled to the feed stream of cell Z. In this case a portion of the alkali metal hydroxide is recycled.
A greater or lesser proportion of the alkali metal hydroxide content of the feed stream can be derived from recycled hydroxide solution. Preferably all of the alkali metal hydroxide in the feed stream is derived from recycled solution, so that no alkali metal hydroxide has to be introduced into the process.
The concentrations of the acid in the product stream withdrawn from cell X, of the alkali metal hydroxide in the product stream withdrawn from cell Z, and of the alkali metal salt in the product stream withdrawn from cell Y, depend on the concentrations of the respective feed streams as well as on the reaction conditions of the 2oo96~6 electrodialysis, such as the capacity of the dialyzer, the residence times of the feed streams in the cells, the temperature, the voltage and the current.
Depending on the reaction conditions of the electrodialysis, the difference in concentration between the inlets and outlets of the cells may be larger or smaller.
Preferably the reaction conditions are selected such that the difference in concentration between the inlet and outlet of the cells is small, i.e., such that the concentration of the acid solution or alkali hydroxide solution withdrawn from the electrodialyzer is only slightly higher than the concentration of the acid solution or alkali hydroxide solution introduced into the electrodialyzer.
Advantageously, a large proportion of the product streams is thereby recirculated, and only a small portion is withdrawn. The difference can be compensated for by addition of water.
The feed streams to cells X and Z should be substantially salt-free. The expression, "substantially salt-free," as used in connection with the present invention, is to be understood to mean that, except for any slight contamination that may be present, no salts are present in solution. The alt content of the feed streams to cells X and Z should be, for example, less than about 0.1 wt%.
For the carbonation, the alkali metal hydroxide solution withdrawn from cell Z, after diverting a portion that is recycled to the feed stream, is introduced into a carbonator and mixed with gaseous CO2 and/or with solutions of the hydrogen carbonates of the particular alkali metal, so as to form the carbonic acid salts of the alkali metal.
The exhaust gas from a combustion process or from a lime kiln, for example, can be used as the carbon dioxide gas. It can also be obtained, however, by reacting carbonic acid salts, particularly CaC03, with an acid. The method of the present invention preferably makes use of carbon dioxide 2009~16 that has been released by the reaction of CaCO3 with the acid taken from cell X. Accordingly, in a preferred embodiment of the present invention, the enriched aqueous acld solution obtained as a product stream from cell X in step a), after diverting in some cases a portion to be recycled to the feed stream of cell X, is reacted at least partially wlth calcium carbonate, and the C02 gas that is formed is introduced into the carbonator in step b).
Within the scope of the invention, step b), i.e., the carbonation of the alkali metal hydroxide solution obtained in step a), and step c), i.e., the separation of the carbonic salts of the alkali metal which are obtained in stsp b), can be carried out in known manner. For example, a method is disclosed in German Patent No. DE 954 414 for the production of anhydrous, gritty alkali carbonate, the formation and isolation of the carbonate being performed in a single step. In this method, powdered or finely granular alkali carbonate is introduced into a fluidized-bed oven, fluidized with hot gases containing CO2, and alXali lye is sprayed into the fluidized bed. Due to the high temperature of the gases (about 300 to about 450C for the production of sodium carbonate, and about 250 to about 400C for the production of potassium carbonate), the resulting carbonates are anhydrous.
In the method of the invention, the carbonation of the alkali metal hydroxide solution and separation of the carbonic acid salts of the alkali metal can also be carried out separately from each other at different times and/or at different locations.
Step b), i.e., the carbonation, can be performed by contacting the alkali hydroxide solution collected from step a) with gases containing carbon dioxide in Gne or more stirring vessels or in one or more successively arranged perforated-tray or packed columns, or in spray towers.
201~9616 Step c), i.e., the separation of the carbonic aid salts of the alkali metal from the liquid flowing out of the carbonator, which contains the carbonic acid salts of the alkali metal in solution and, in some cases, in suspension, can be performed in a known manner. For example, if an aqueous suspension has been obtained from step b), it can first be concentrated in a concentrator or a centrifugal separator. Also, a solution or suspension obtained in step b) can be concentrated, e.g., by evaporating the water, with the aid of a vacuum if desired, or by treating the solution by ultrafiltration or reverse osmosis.
Also, the hydrogen carbonate salts of the alkali metals can be obtained by "supercarbonation," i.e., the reaction of alkali lye or alkali carbonate for example with cooled C02 gas in sprinkler towers. The resulting crystals can then be extracted by centrifugation and dried.
The process of the present invention has the following advantages:
- The method of the invention permits the energy-saving manufacture of pure alkali carbonates and alkali hydrogen carbonates from alkali salts and carbon dioxide without requiring the use of mercury.
- By-products are produced, such as inorganic acids and/or salt solutions, e.g., solutions of CaCl2, which due to their purity constitute valuable intermediate products.
- The method of the invention permits direct production of carbonic acid salts of alkali metals which can be used for pharmaceutical purposes and/or as additives in the food industry without complex purifying operations.
Without limiting the scope of the invention, the method of the invention will be described in further detail in the following example with reference to Figure 2, which represents a flow diagram of a preferred embodiment.
A commercially available apparatus with eight separator units, a voltage of 20 volts and a current of 10 amperes was used as the electrodialyzing apparatus 1. The basic method of operation of such a dialyzer has already been described with reference to Figure 1. The electro-dialysis was carried out at about 40c.
Through a conduit 2, an aqueous, saturated potassium chloride solution (potassium chloride content about 28% by weight), which also contained about 1000 ppm of magnesium chloride, was initially passed through a filter t0.1 mm mesh width) to remove any solids it might contain. The solution leaving the filter was introduced as a feed stream into cells Y.
An aqueous hydrochloric acid solution having a concentration of about 4 wt% HCl was introduced through a feed line 3 into cells X.
A potash lye having a concentration of about 15 wt% KOH
was introduced through a feed line 4 into cells Z.
The applied direct current of about 20 volts produced the transfer of Cl ions from the Y cells to the X cells and of K~ ions to the Z cells.
The volumetric flow rates of the feed streams were regulated such that an approximately 5% hydrochloric acid solution from the X cells, and an approximately 18% potash lye from the Z cells, were obtained as product streams. The KCl solution coming from cell Y was recycled after addition of fresh KCl up to the saturation point of about 28 wt%.
This saturated potassium chloride solution was then introduced as a feed stream through the filter and conduit 2 into cells Y.
The hydrochloric acid solution enriched to about 5 wt%
HCl was withdrawn from the X cells through conduit 8. A
portion of the product stream was diverted from conduit 8 through conduit 16 and mixed with water to obtain a hydrochloric acid solution of about 4 wt% HCl. This hydrochloric acid solution constituted the feed stream for 2009~6 the X cells. In this manner a portion of the hydrochloric acid solution was recycled.
A potash lye having a KOH content of about 18 wt~ was withdrawn from the Z cells. A portion of the product stream was diverted from conduit g through conduit 15 and mixed with water to obtain a potassium hydroxide solution having a concentration of about 15 wt% KOH. This solution constituted the feed stream for the Z cells. In this manner a portion of the potassium hydroxide solution was recycled.
The stream of hydrochloric acid solution that was not diverted for recycling was introduced into a lime dissolver 18 into which an amount of pulverized limestone corresponding to the amount of acid was continuously fed by a vibrating trough 17. The calcium chloride solution formed in the reaction between the aqueous hydrochloric acid solution and the limestone was withdrawn from the lime dissolver 18 through an overflow and carried away through a conduit 19, while the carbon dioxide gas formed in the reaction was injected into a carbonator 11 through line 10 from a water separator (not shown in Fig. 2).
At the same time the stream of potassium hydroxide solution that was not diverted for recycling was fed through line 9 into the carbonator 11. A conventional column was used as the carbonator. The suspension leaving the carbonator was concentrated and introduced into a crystallizer 12 and separated into solid material and a solution substantially free of solids. The solids were transferred to a dryer 13, dried there by hot air at a temperature of about 110 to 120C, and discharged from the dryer through the conduit 14. The resulting hydrated potash, corresponding to the formula K2CO3~1.5 H2O, had a purity of 99.1% and contained only 10 ppm of MgCl2. The yield amounted to about 85%, based on the amount of KCl used.
20096'~ 6 The foregoing description and examples have been set forth merely to illustrate the invention and are not intended to be limiting. Since modifications of the described embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the scope of the invention should be construed to include e~erything falling within the ambit of the appended claims and equivalents thereof.
Claims (14)
1. A method for producing a carbonic acid salt of an alkali metal from an aqueous inorganic alkali metal salt solution in which the aqueous alkali metal salt solution is converted to an alkali metal hydroxide solution and subsequently carbonated, comprising the steps of:
a) providing an electrodialyzer comprising an anode, a cathode, and at least one dialysis unit bounded by bipolar or cation-selective membranes and subdivided into:
- a cell X arranged toward said anode and bounded on its side oriented toward said anode by a cation selective layer of a bipolar membrane, - a cell Z arranged toward said cathode and bounded on its side oriented toward said cathode by an anion selective layer of a bipolar membrane, and - a middle cell Y arranged between cells X and Z, and separated from cell X by an anion-selective membrane and from cell Z by a cation-selective membrane, and subjecting the alkali metal salt solution to electrodialysis in said electrodialyzer by:
- introducing an aqueous inorganic alkali metal salt solution as a feed stream into cell Y, a substantially salt-free aqueous solution of the acid corresponding to the alkali metal salt as a feed stream into cell X, and a substantially salt-free aqueous solution of the alkali metal hydroxide corresponding to the alkali metal salt as a feed stream into cell Z;
- passing electric current through the electrodialyzer by applying a direct current voltage across said anode and cathode; and - collecting a depleted alkali metal salt solution as a product stream from cell Y, an enriched aqueous solution of the inorganic acid corresponding to the alkali metal salt from cell X, and an enriched solution of the alkali metal hydroxide corresponding to the alkali metal salt as a product stream from cell Z; and b) introducing the alkali metal hydroxide solution collected in step a) to a carbonator and mixing it with a reagent selected from the group consisting of gaseous carbon dioxide and a solution of the hydrogen carbonate of the alkali metal, for carbonation to form a carbonic acid salt of the alkali metal; and c) recovering the carbonic acid salt of the alkali metal formed in step b).
a) providing an electrodialyzer comprising an anode, a cathode, and at least one dialysis unit bounded by bipolar or cation-selective membranes and subdivided into:
- a cell X arranged toward said anode and bounded on its side oriented toward said anode by a cation selective layer of a bipolar membrane, - a cell Z arranged toward said cathode and bounded on its side oriented toward said cathode by an anion selective layer of a bipolar membrane, and - a middle cell Y arranged between cells X and Z, and separated from cell X by an anion-selective membrane and from cell Z by a cation-selective membrane, and subjecting the alkali metal salt solution to electrodialysis in said electrodialyzer by:
- introducing an aqueous inorganic alkali metal salt solution as a feed stream into cell Y, a substantially salt-free aqueous solution of the acid corresponding to the alkali metal salt as a feed stream into cell X, and a substantially salt-free aqueous solution of the alkali metal hydroxide corresponding to the alkali metal salt as a feed stream into cell Z;
- passing electric current through the electrodialyzer by applying a direct current voltage across said anode and cathode; and - collecting a depleted alkali metal salt solution as a product stream from cell Y, an enriched aqueous solution of the inorganic acid corresponding to the alkali metal salt from cell X, and an enriched solution of the alkali metal hydroxide corresponding to the alkali metal salt as a product stream from cell Z; and b) introducing the alkali metal hydroxide solution collected in step a) to a carbonator and mixing it with a reagent selected from the group consisting of gaseous carbon dioxide and a solution of the hydrogen carbonate of the alkali metal, for carbonation to form a carbonic acid salt of the alkali metal; and c) recovering the carbonic acid salt of the alkali metal formed in step b).
2. A method according to Claim 1, wherein said alkali metal salt is an alkali metal halide.
3. A method according to Claim 2, wherein said alkali metal halide is an alkali metal chloride.
4. A method according to Claim 1, wherein said alkali metal salt is a potassium salt.
5. A method according to Claim 1, wherein in step a) a portion of the aqueous acid solution withdrawn as a product stream from cell X is recycled to the feed stream to cell X.
6. A method according to Claim 5, wherein an amount of aqueous acid solution sufficient to obtain an acid concentration of from 1 to 10 wt%, is recycled to the feed stream to cell X.
7. A method according to Claim 6, wherein an amount of aqueous acid solution sufficient to obtain an acid concentration of from 3 to 5 wt% is recycled to the feed stream to cell X.
8. A method according to Claim 1, wherein in step a) a portion of the aqueous alkali metal hydroxide solution withdrawn from cell Z as a product stream, is recycled to the feed stream to cell Z.
9. A method according to Claim 8, wherein an amount of the aqueous alkali metal hydroxide solution sufficient to produce an alkali hydroxide concentration of from 0.5 to 50 wt% is recycled to the feed stream to cell Z.
10. A method according to Claim 9, wherein an amount of aqueous alkali metal hydroxide solution sufficient to produce an alkali hydroxide concentration of from 2 to 25 wt% is recycled to the feed stream to cell Z.
11. A method according to Claim 10, wherein an amount of aqueous alkali metal hydroxide solution sufficient to produce an alkali hydroxide concentration of from 12 to 18 wt% is recycled to the feed stream to cell Z.
12. A method according to Claim 1, wherein the enriched aqueous acid solution obtained in step a) as a product stream from cell X, is at least partially reacted with calcium carbonate to produce CO2 gas, and the resulting CO2 gas is introduced into the carbonator in step b).
13. A method according to Claim 1, wherein the feed stream for cell Y is a saturated alkali metal salt solution.
14. A method according to Claim 13, wherein enriched alkali metal salt solution obtained as a product stream from cell Y, is resaturated by addition of alkali metal salt and returned as a feed stream to cell Y.
Priority Applications (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3834807A DE3834807A1 (en) | 1988-10-13 | 1988-10-13 | METHOD FOR PRODUCING CARBONIC SALTS OF ALKALI METALS |
| EP90101631A EP0439636A1 (en) | 1988-10-13 | 1990-01-27 | Alkali metal (hydrogen) carbonate production process |
| CA002009616A CA2009616A1 (en) | 1988-10-13 | 1990-02-08 | Method of producing carbonic acid salts of alkali metals |
| ZA901038A ZA901038B (en) | 1988-10-13 | 1990-02-12 | Process for producing carbonates of alkali metals |
| JP2031661A JPH03245824A (en) | 1988-10-13 | 1990-02-14 | Manufacture of alkali metal carbonate |
| BR909000759A BR9000759A (en) | 1988-10-13 | 1990-02-19 | PROCESS FOR OBTAINING ALKALINE METAL CARBONATES |
| CN90100955A CN1054234A (en) | 1988-10-13 | 1990-02-24 | The manufacture method of alkaline carbonate |
| AU51329/90A AU621463B2 (en) | 1988-10-13 | 1990-03-15 | Method for the preparation of carbonic acid salts of alkali metals |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3834807A DE3834807A1 (en) | 1988-10-13 | 1988-10-13 | METHOD FOR PRODUCING CARBONIC SALTS OF ALKALI METALS |
| CA002009616A CA2009616A1 (en) | 1988-10-13 | 1990-02-08 | Method of producing carbonic acid salts of alkali metals |
| ZA901038A ZA901038B (en) | 1988-10-13 | 1990-02-12 | Process for producing carbonates of alkali metals |
| CN90100955A CN1054234A (en) | 1988-10-13 | 1990-02-24 | The manufacture method of alkaline carbonate |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2009616A1 true CA2009616A1 (en) | 1991-08-08 |
Family
ID=36754830
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002009616A Abandoned CA2009616A1 (en) | 1988-10-13 | 1990-02-08 | Method of producing carbonic acid salts of alkali metals |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0439636A1 (en) |
| JP (1) | JPH03245824A (en) |
| CN (1) | CN1054234A (en) |
| AU (1) | AU621463B2 (en) |
| BR (1) | BR9000759A (en) |
| CA (1) | CA2009616A1 (en) |
| DE (1) | DE3834807A1 (en) |
| ZA (1) | ZA901038B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8865096B2 (en) | 2010-06-22 | 2014-10-21 | Solvay Sa | Process for the joint production of sodium carbonate and sodium bicarbonate |
| CN105849047A (en) * | 2013-10-23 | 2016-08-10 | 内玛斯卡锂公司 | Processes for preparing lithium carbonate |
| US9422166B2 (en) | 2008-01-08 | 2016-08-23 | Solvay (Societe Anonyme) | Process for producing sodium bicarbonate |
| US9868644B2 (en) | 2011-12-23 | 2018-01-16 | Solvay Sa | Process for the joint production of sodium carbonate and sodium bicarbonate |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2729305A1 (en) * | 1995-01-18 | 1996-07-19 | Atochem Elf Sa | REGENERATION OF STRONG ORGANIC ACIDS BY BIPOLAR MEMBRANES |
| JP4061902B2 (en) * | 2001-12-25 | 2008-03-19 | 旭硝子株式会社 | Method for producing porous potassium carbonate |
| EP1900688A1 (en) * | 2006-09-14 | 2008-03-19 | SOLVAY (Société Anonyme) | Method for obtaining sodium carbonate crystals |
| EP2078697A1 (en) * | 2008-01-08 | 2009-07-15 | SOLVAY (Société Anonyme) | Process for producing sodium carbonate and/or sodium bicarbonate from an ore mineral comprising sodium bicarbonate |
| EP2749535B1 (en) * | 2010-02-17 | 2019-07-31 | All American Lithium LLC | Processes for preparing highly pure lithium carbonate and other highly pure lithium containing compounds |
| AU2010351550B2 (en) * | 2010-04-23 | 2014-03-20 | Terralithium Llc | A process for making lithium carbonate from lithium chloride |
| KR102140915B1 (en) * | 2018-11-27 | 2020-08-05 | 한국에너지기술연구원 | Carbon dioxide mineralization reactor and carbon dioxide immobilization method |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE954414C (en) * | 1954-09-16 | 1956-12-20 | Basf Ag | Process for the production of anhydrous alkali carbonates in gritty form |
| US4219396A (en) * | 1979-08-03 | 1980-08-26 | Allied Chemical Corporation | Electrodialytic process |
| DE3381495D1 (en) * | 1983-03-14 | 1990-05-31 | Allied Signal Inc | ACID FORMATION IN LAUGES WITH SIMULTANEOUS PRODUCTION OF ALKALINE METAL HYDROXIDE AND SALT ACID THROUGH WATER DECOMPOSITION IN AN ELECTRODIALYSIS APPARATUS THREE CHAMBER TYPES. |
| US4880513A (en) * | 1986-06-20 | 1989-11-14 | The Graver Company | Method and apparatus for generating acid and base regenerants and the use thereof to regenerate ion-exchange resins |
| US5162076A (en) * | 1988-11-30 | 1992-11-10 | Allied-Signal Inc. | Method for purification of acids from materials comprising acid and salt |
| US4976838A (en) * | 1988-12-01 | 1990-12-11 | Allied-Signal Inc. | Method for purification of bases from materials comprising base and salt |
-
1988
- 1988-10-13 DE DE3834807A patent/DE3834807A1/en not_active Withdrawn
-
1990
- 1990-01-27 EP EP90101631A patent/EP0439636A1/en not_active Withdrawn
- 1990-02-08 CA CA002009616A patent/CA2009616A1/en not_active Abandoned
- 1990-02-12 ZA ZA901038A patent/ZA901038B/en unknown
- 1990-02-14 JP JP2031661A patent/JPH03245824A/en active Pending
- 1990-02-19 BR BR909000759A patent/BR9000759A/en not_active Application Discontinuation
- 1990-02-24 CN CN90100955A patent/CN1054234A/en active Pending
- 1990-03-15 AU AU51329/90A patent/AU621463B2/en not_active Ceased
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9422166B2 (en) | 2008-01-08 | 2016-08-23 | Solvay (Societe Anonyme) | Process for producing sodium bicarbonate |
| US8865096B2 (en) | 2010-06-22 | 2014-10-21 | Solvay Sa | Process for the joint production of sodium carbonate and sodium bicarbonate |
| US9868644B2 (en) | 2011-12-23 | 2018-01-16 | Solvay Sa | Process for the joint production of sodium carbonate and sodium bicarbonate |
| CN105849047A (en) * | 2013-10-23 | 2016-08-10 | 内玛斯卡锂公司 | Processes for preparing lithium carbonate |
| CN105849047B (en) * | 2013-10-23 | 2018-11-13 | 内玛斯卡锂公司 | The method for preparing lithium carbonate |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1054234A (en) | 1991-09-04 |
| AU621463B2 (en) | 1992-03-12 |
| JPH03245824A (en) | 1991-11-01 |
| DE3834807A1 (en) | 1990-05-10 |
| ZA901038B (en) | 1990-11-28 |
| EP0439636A1 (en) | 1991-08-07 |
| AU5132990A (en) | 1991-10-31 |
| BR9000759A (en) | 1991-10-15 |
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