GB2024187A - Process for producing anhydrous sodium carbonate - Google Patents
Process for producing anhydrous sodium carbonate Download PDFInfo
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- GB2024187A GB2024187A GB7922190A GB7922190A GB2024187A GB 2024187 A GB2024187 A GB 2024187A GB 7922190 A GB7922190 A GB 7922190A GB 7922190 A GB7922190 A GB 7922190A GB 2024187 A GB2024187 A GB 2024187A
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- sodium carbonate
- process according
- anhydrous sodium
- transition
- monohydrate
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- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 title claims abstract description 170
- 238000000034 method Methods 0.000 title claims description 42
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims abstract description 64
- 229910000029 sodium carbonate Inorganic materials 0.000 claims abstract description 53
- 230000007704 transition Effects 0.000 claims abstract description 45
- MQRJBSHKWOFOGF-UHFFFAOYSA-L disodium;carbonate;hydrate Chemical compound O.[Na+].[Na+].[O-]C([O-])=O MQRJBSHKWOFOGF-UHFFFAOYSA-L 0.000 claims abstract description 42
- 229940076133 sodium carbonate monohydrate Drugs 0.000 claims abstract description 41
- 239000011780 sodium chloride Substances 0.000 claims abstract description 32
- 229940001593 sodium carbonate Drugs 0.000 claims abstract description 26
- 239000007864 aqueous solution Substances 0.000 claims abstract description 15
- 229920006395 saturated elastomer Polymers 0.000 claims abstract description 9
- 235000017550 sodium carbonate Nutrition 0.000 claims description 52
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 27
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 claims description 18
- 239000000243 solution Substances 0.000 claims description 17
- 239000012452 mother liquor Substances 0.000 claims description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 16
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 13
- 238000000926 separation method Methods 0.000 claims description 13
- 238000002425 crystallisation Methods 0.000 claims description 12
- 230000008025 crystallization Effects 0.000 claims description 12
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 12
- 235000011152 sodium sulphate Nutrition 0.000 claims description 12
- 239000002002 slurry Substances 0.000 claims description 11
- 235000017557 sodium bicarbonate Nutrition 0.000 claims description 9
- 229910000030 sodium bicarbonate Inorganic materials 0.000 claims description 9
- 238000005406 washing Methods 0.000 claims description 9
- 238000005868 electrolysis reaction Methods 0.000 claims description 7
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims description 4
- 235000019270 ammonium chloride Nutrition 0.000 claims description 2
- 238000006243 chemical reaction Methods 0.000 claims description 2
- 230000036571 hydration Effects 0.000 claims description 2
- 238000006703 hydration reaction Methods 0.000 claims description 2
- 239000007787 solid Substances 0.000 claims description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims 2
- 238000009621 Solvay process Methods 0.000 claims 1
- 239000001569 carbon dioxide Substances 0.000 claims 1
- 229910002092 carbon dioxide Inorganic materials 0.000 claims 1
- 235000011182 sodium carbonates Nutrition 0.000 claims 1
- 238000005507 spraying Methods 0.000 claims 1
- 239000013078 crystal Substances 0.000 description 49
- 239000007832 Na2SO4 Substances 0.000 description 8
- 230000000704 physical effect Effects 0.000 description 7
- 108091006629 SLC13A2 Proteins 0.000 description 5
- 238000010521 absorption reaction Methods 0.000 description 5
- 239000011521 glass Substances 0.000 description 5
- 239000012535 impurity Substances 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 3
- 241000276425 Xiphophorus maculatus Species 0.000 description 3
- 238000004090 dissolution Methods 0.000 description 3
- 238000001354 calcination Methods 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000010298 pulverizing process Methods 0.000 description 2
- 239000012047 saturated solution Substances 0.000 description 2
- JVBXVOWTABLYPX-UHFFFAOYSA-L sodium dithionite Chemical compound [Na+].[Na+].[O-]S(=O)S([O-])=O JVBXVOWTABLYPX-UHFFFAOYSA-L 0.000 description 2
- QNRATNLHPGXHMA-XZHTYLCXSA-N (r)-(6-ethoxyquinolin-4-yl)-[(2s,4s,5r)-5-ethyl-1-azabicyclo[2.2.2]octan-2-yl]methanol;hydrochloride Chemical compound Cl.C([C@H]([C@H](C1)CC)C2)CN1[C@@H]2[C@H](O)C1=CC=NC2=CC=C(OCC)C=C21 QNRATNLHPGXHMA-XZHTYLCXSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- WJHHDDHKGDBWIH-UHFFFAOYSA-M azanium sodium hydrogen carbonate chloride hydrate Chemical compound O.C([O-])(O)=O.[Na+].[Cl-].[NH4+] WJHHDDHKGDBWIH-UHFFFAOYSA-M 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- OCLWHYOULMTOJB-UHFFFAOYSA-L disodium hydrogen carbonate hydrate Chemical compound O.[Na+].[Na+].OC(O)=O.[O-]C([O-])=O OCLWHYOULMTOJB-UHFFFAOYSA-L 0.000 description 1
- SDCJMBBHNJPYGW-UHFFFAOYSA-L disodium;hydrogen carbonate;chloride Chemical compound [Na+].[Na+].Cl.[O-]C([O-])=O SDCJMBBHNJPYGW-UHFFFAOYSA-L 0.000 description 1
- 230000012447 hatching Effects 0.000 description 1
- 230000000887 hydrating effect Effects 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 150000004682 monohydrates Chemical class 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- PFUVRDFDKPNGAV-UHFFFAOYSA-N sodium peroxide Chemical compound [Na+].[Na+].[O-][O-] PFUVRDFDKPNGAV-UHFFFAOYSA-N 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
Classifications
-
- 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
- C01D7/35—Varying the content of water of crystallisation or the specific gravity
- C01D7/37—Densifying sodium carbonate
-
- 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
- C01D7/35—Varying the content of water of crystallisation or the specific gravity
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Glass Compositions (AREA)
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
Abstract
Anhydrous sodium carbonate which has high bulk density, high fluidity and high hardness and is non- hygroscopic in air is produced by converting sodium carbonate monohydrate into anhydrous sodium carbonate by a transition in a saturated aqueous solution of sodium carbonate containing from 10 to 22 wt.% of sodium chloride which is heated at a temperature of from 3 to 7 DEG C higher than its transition temperature.
Description
SPECIFICATION
Process for producing anhydrous sodium carbonate
The present invention relates to a process for producing sodium carbonate having improved physical characteristics.
Sodium carbonate has been produced by the following processes.
(1) Crude sodium bicarbonate obtained by the Solvay soda process or the ammonium chloride soda process is calcined to produce sodium carbonate (light soda ash).
2NaHCO3e Na2CO3 + H20 + CO2 (1)
(2) Light soda ash is hydrated to produce sodium carbonate monohydrate which is calcined to produce sodium carbonate (dense soda ash).
Na2CO3 + H20 < Na2CO3. H20 (2) Na2CO3 . H20e Na2CO3 + H20 (3)
(3) Sodium hydroxide is carbonated to produce sodium carbonate monohydrate which is calcined to produce sodium carbonate (dense soda ash).
2NaOH + CO2 < Na2CO3. H20 (4)
However, in the light soda ash obtained by process (1), the crude sodium bicarbonate is in a brittle crystalline form whereby it is pulverized in the conversion to the soda ash by the equation (1 ) to give a low bulk density of 0.8 to 1.0. Accordingly, it is not suitable to be used as a raw material for glass, which is the most important use of sodium carbonate. The light soda ash has only small scale specialized uses.
The dense soda ash has an improved bulk density of 1.0 to 1.3 and can be used as a raw material for glass.
However, in the calcination of sodium carbonate monohydrate, crystalline water is evaporated from the crystals of the sodium carbonate monohydrate whereby porous crystals having fine voids are formed as the anhydrous sodium carbonate. Accordingly, the bulk density is less than 1.3, and the anhydrous sodium carbonate is pulverized during its handling and does not easily flow. There are many other problems to overcome. The dense soda ash has the same form as that of the sodium carbonate monohydrate used as the raw material. In order to produce a dense soda ash having the desired shape, it is necessary to produce sodium carbonate monohydrate having a desired crystalline shape.
Sodium carbonate monohydrate has a hexagonal plate-like crystalline form having thickness in a rhombic system as its apparent crystalline form. Accordingly, the anhydrous sodium carbonate has a hexagonal plate-like form even though it is converted. The particles of the product do not turn to reduce its fluidity.
Moreover, the light soda ash or dense soda ash is easily converted to sodium carbonate monohydrate by its transition. It requires careful handling.
Japanese Patent Publication No. 16664/1971 discloses a process for producing dense soda ash by heating sodium carbonate hydrate crystals in an aqueous solution which can contain sodium hydroxide to convert it into anhydrous sodium carbonate crystals and directly separating the crystals from the mother liquor. In accordance with this known process, it is necessary to pressurize the aqueous solution, since the solution has a boiling point of 105"C, but the transition temperature for converting the hydrate into anhydrous sodium carbonate is higher than 105"C.
On the other hand, when the transition is carried out in the presence of sodium hydroxide in order to enable the transition to take place under atmospheric pressure, sodium hydroxide adheres to the anhydrous sodium carbonate. In washing the product to remove sodium hydroxide, a part of the anhydrous sodium carbonate is hydrated to give a product having a higher water content. The anhydrous sodium carbonate has also the disadvantages of relatively low bulk density, pulverizability and inferior fluidity.
It is an object of the present invention to produce sodium carbonate having higher bulk density than that of the dense soda ash produced by the conventional process while being non-hygroscopic with moisture in the air and having high fluidity and high hardness to prevent it pulverizing.
The present invention provides a process for producing an hydrous sodium carbonate which comprises converting sodium carbonate monohydrate into an hydros sodium carbonate by a transition in a saturated aqueous solution of sodium carbonate containing from 10 to 22 wt. % of sodium chloride which is heated at a temperature of from 3 to 7"C higher than its transition temperature.
The accompanying drawing shows a temperature range for the process for converting sodium carbonate monohydrate into anhydrous sodium carbonate by its transition depending upon the concentration of sodium chloride in a saturated aqueous solution of sodium carbonate.
The inventors have found the fact that a different transition mechanism is involved when converting sodium carbonate monohydrate into anhydrous sodium carbonate by its transition under the special conditions and in the presence of the specific concentration of sodium chloride used in the presence of the invention whereby the above-mentioned disadvantages of the conventional process can be overcome.
The conditions used for the process of the present invention and the effects thereof will be further illustrated.
When sodium carbonate monohydrate is fed into a crystallization vessel heated to a temperature higher than the transition temperature, the transition is performed by the following steps:
Dissolution of sodium carbonate mono hydrate < formation of super-saturation of sodium carbonate growth of crystals of an hydrous carbonate or growth of nuclei thereof.
The nuclei formed in the presence of crystals are usually called secondary nuclei. When the secondary nuclei of anhydrous sodium carbonate are grown, only flat crystals are present before feeding sodium carbonate monohydrate, the desired round shaped crystals are formed during growing the crystals which are previously present. However, when sodium carbonate monohydrate is further added, the crystals become flat and have a bulk density of from 1.0 to 1.3.
However, when sodium carbonate monohydrate is fed to convert it into anhydrous sodium carbonate by its transition in the presence of 10 to 22 wt.% of sodium chloride at a temperature of from 3 to 7"C higher than its transition temperature, no secondary nuclei for forming flat grown crystals are formed, but rod shape secondary nuclei which are grown to form spherical crystals are formed.
It is not clearly understood why the properties of the resulting secondary nuclei are different depending upon the conditions. In accordance with the observation, the nuclei are not formed from the solution, but formed from inner parts of the crystals of sodium carbonate monohydrate when rod shaped secondary nuclei are formed. That is, the dissolution of sodium carbonate monohydrate is stopped when the nuclei are formed, and the sodium carbonate monohydrate is converted into the anhydrous sodium carbonate by its transition without a dissolution. Accordingly, the crystals of sodium carbonate monohydrate are converted into agglomerates of nuclei of the anhydrous sodium carbonate, which are pulverized by a shock such as stirring.
Such phenomenon is not substantially found under a condition out of the above-mentioned ranges.
Thus, the physical property is remarkably improved. In order to produce spherical crystals of anhydrous sodium carbonate, it is important to select the condition for forming the rod shaped secondary nuclei. The additional feature is to be smaller effect of an impurity even though the impurity is included in the solution.
That is, the effect of the impurity is substantially negligible because the secondary nuclei are not formed from the solution and also the effect of a small amount of the impurity for crystallization is not substantially imparted because the rod shaped secondary nuclei have a property for growing to form spherical crystals.
However, only sulfate ion affects to the growth of the rod shaped secondary nuclei. When a content of sulfate ion is higher than 0.2 wt.% as Na2SO4, it causes a tendencyforforming flat shape from the spherical shape and anhydrous sodium carbonate having excellent characteristics can not be usually obtained.
The process of the present invention will be further illustrated.
Sodium carbonate monohydrate as the raw material can be sodium carbonate monohydrate obtained by producing light soda ash by calcining a crude sodium bicarbonate obtained by Solvay soda process of the ammonium chloride sodium carbonate monohydrate obtained by a carbonatation of an aqueous solution of sodium hydroxide. It can be also sodium carbonate monohydrate obtained by a carbonatation an electrolyzed solution obtained by a diaphragm electrolysis of sodium chloride with sodium dioxide gas or sodium bicarbonate. The slurry of sodium carbonate monohydrate obtained by a carbonatation of the electrolyzed solution obtained by the diaphragm electrolysis of sodium chloride, contains sodium chloride whereby the slurry can be fed without a separation of crystals etc., into a vessel for converting into the anhydrous sodium carbonate.
When a content of sulfate ion is more than 0.2 wt.% as Na2SO4, it is preferable to separate partially or completely the crystals from the mother liquor in order to obtain a desired anhydrous sodium carbonate. It is not possible to obtain the anhydrous sodium carbonate having desired characteristics obtained by the process of the present invention, even though anhydrous sodium carbonate is crystallized after reacting sodium bicarbonate with an electrolyzed solution obtained by the diaphragm electrolysis of sodium chloride.
It is necessary to give from 10 to 22 wt.% of a concentration of sodium chloride in the saturated solution of sodium carbonate in the vessel for the transition. At the different concentration of sodium chloride, rod shaped secondary nuclei can not be formed and the desired anhydrous sodium carbonate can not be obtained even though a temperature in the vessel is controlled.
It is necessary to perform the transition from sodium carbonate monohydrate into anhydrous sodium carbonate at a temperature of from 3 to 7"C higher than its transition temperature.
When the temperature in the vessel is higher than 7"C over the transition temperature, agglomerated crystals are formed, but spherical crystals are not formed. On the other hand, when it is lower than 3"C over the transition temperature, desired crystals can not be obtained and the transition to the anhydrous sodium carbonate is remarkably slow and it is not practically operated. The range of the temperature for from 3 to 7"C higher than the transition temperature depending upon the concentration of sodium chloride in the aqueous saturated solution of sodium carbonate is shown in Figure 1 by the hatching line.
The transition temperature in the specification is measured by the following method.
In a 1 liter glass flask, 800 ml of a saturated aqueous solution of sodium carbonate and sodium chloride at specific concentrations thereof was charged and evaporated by heating by a heater under a reduced pressure at an evaporation speed of water of about 50 cc/hour whereby the crystals are precipitated. The concentrations of the components are varied depending upon the evaporation of water and the precipitation of crystals. An aqueous solution of sodium carbonate having a concentration of about 30 wt.% is added through a dropping funnel. When crystals are precipitated, the crystals are analyzed to determine whether they are sodium carbonate monohydrate or anhydrous sodium carbonate. The operation is repeated at various temperatures in various concentrations.The temperature for forming a mixture of sodium carbonate monohydrate and anhydrous sodium carbonate is decided as its transitional temperature.
Note
Concentration of Concentration of
sodium chloride sodium carbonate
Example1 10wt.% 20wt.% Example 2 15 wt.% 16 wt.% Example 3 20 wt.% 11 wt.%
The linear growth speed of the rod shaped secondary nuclei is about 0.06 mm/hour. A desired length of anhydrous sodium carbonate can be obtained by setting a crystal resident time for a desired average length of the crystals. The slurry of anhydrous sodium carbonate obtained by the transition from sodium carbonate monohydrate to anhydrous sodium carbonate can be separated by suitable method such as a centrifugal separation. It is possible to wash the crystals of anhydrous sodium carbonate to remove sodium chloride.
The mother liquor adhered on the crystals of anhydrous sodium carbonate can be removed by washing with several % of a washing liquid based on the crystals. Even though cold water is used as a washing liquid, a hydration is not substantially caused during its washing. When the crystals are dried immediately after the separation and the washing, it is possible to obtain anhydrous sodium carbonate having a water content of less than 1 wt.% especially about 0.2 wt.%.
The preferable embodiments of the process will be further described.
The solution of sodium carbonate containing sodium chloride in the transition vessel is saturated since sodium carbonate monohydrate or anhydrous sodium carbonate is included in a form of slurry. Accordingly, the solution fed to the transition vessel can be saturated or non-saturated, but it should contain sodium chloride to give a concentration of 10 to 22 wt.% in the transition vessel. The range of the temperature for from 3 to 7"C higher than the transition temperature shown in Figure 1 is ranging from (110.4 - 0.42 x) C to (114.4 - 0.42 x) C, wherein x designates a concentration of sodium chloride by weight.
In a separation of anhydrous sodium carbonate from the mother liquor, it is preferable to perform the separation by maintaining a temperature of the slurry at a temperature higher than the transition temperature whereby a transition from anhydrous sodium carbonate to sodium carbonate monohydrate can be prevented. The separation is preferably performed by a centrifugal separation so as to shorten a time for contacting anhydrous sodium carbonate with the mother liquor at a temperature lower than the transition temperature.
The resulting anhydrous sodium carbonate can be washed with water or an aqueous solution of sodium carbonate. It is necessary to shorten the time for contacting the washing solution with an hydrous sodium carbonate. It is preferable to spray the washing solution to anhydrous sodium carbonate rotated in a centrifugal separator.
The other characteristics of the resulting anhydrous sodium carbonate will be described.
(1) A bulk density is ranging from 1.3 to 1.6 which are remarkably higher than that of the conventional dense soda ash.
(2) A fluidity is excellent to be easily transferred.
(3) Moisture in air is not substantially absorbed even though it is kept in air.
(4) Hardness is high enough to prevent a pulverizing during its handling.
The present invention will be illustrated by certain examples and references which are provided for purposes of illustration only and are not intended to be limiting the present invention.
EXAMPLE 1
In a5 liter complete mixing type crystallization vessel, an aqueous solution containing 15.5 wt.% of sodium carbonate and 15.0 wt.% of sodium chloride was fed at a rate of 3200 g/hour, and crystals of hexagonal platy crystals of sodium carbonate monohydrate (A particle distribution is shown in Table 1) obtained by hydrating light soda ash obtained by Solvay soda process was fed at a rate of 1200 g/hour.The temperature in the crystallization vessel was maintained at 106"C. The resulting slurry of anhydrous sodium carbonate was separated by a centrifugal separation at 102 to 104"C whereby a cake of anhydrous crystals was obtained at a rate of 980 g/hour and a mother liquor containing 13.9wt.% of sodium chloride and 16.5 wt.% of sodium carbonate was obtained at a rate of 3420 g/hour. The cake was immediately dried to obtain anhydrous crystals.
The anhydrous crystals were substantially spherical crystals having an average diameter of 350it and had excellent fluidity and a bulk density of 1.59 which is unexpected in view of the conventional dense soda ash.
The anhydrous crystals had a water content of 0.3 wt.% and a content of sodium chloride of 0.4 wt.%. The crystals were washed with water at a ratio of 3 wt.% based on the cake during the centrifugal separation, whereby sodium chloride was substantially removed. The water content was not substantially increased.
The other characteristics of the anhydrous sodium carbonate are shown in Table 2.
EXAMPLES 2 to 6 and References 1 to 7:
In accordance with the process of Example 1 except varying the concentration of sodium chloride in the mother liquor and the temperature in the crystallization vessel, each transition and tests were carried out.
The result is shown in Table 2.
EXAMPLE 7
In accordance with the process of Example 1 except using hexagonal platy crystals of sodium carbonate monohydrate (A particle distribution is shown in Table 1) obtained by reacting sodium bicarbonate with an electrolyzed solution containing 9.6 wt.% of sodium hydroxide and 16.8 wt.% of sodium chloride obtained by a diaphragm electrolysis of sodium chloride, a transition and tests were carried out. The result was substantially the same with that of Example 1.
EXAMPLE 8
In a 5 liter complete mixing type crystallization vessel, an aqueous slurry having the following formula which contained hexagonal platy crystals of sodium carbonate monohydrate (a particle distribution is the same with that shown in Table 1) having a solid content of 30 wt.% obtained by reacting sodium bicarbonate with an electrolyzed solution containing 9.6 wt.% of sodium hydroxide and 16.8 wt.% of sodium chloride obtained by a diaphragm electrolysis of sodium chloride, at a rate of 4500 g/hour and the temperature in the crystallization vessel was maintained at 1060C to obtain a slurry of anhydrous sodium carbonate.
Na2CO3 15.8wt.% NaC1 15.1 wt.% Na2SO4 0.2 wt.%
Other
In accordance with the process of Example 1, anhydrous sodium carbonate was separated. The result is shown in Table 2. The physical properties are slightly inferior because of the impurity of Na2SO4. The mother liquor contained 14.0 wt.% of sodium chloride and 0.2 wt.% of sodium sulfate.
EXAMPLES 9 to 11:
In accordance with the process of Example 1 except adding Na2SO4 in the aqueous solution so as to give each specified concentration of sodium sulfate in each mother liquor, each transition and separation were carried out. The result is shown in Table 2. When a concentration of sodium sulfate is higherthan 0.2wt.%, a shape of spherical crystals becomes flat.
Reference 8
Sodium carbonate monohydrate used in Example 1 was converted into a dense soda ash by a conventional process. The physical properties are shown in Table 2.
Measurements of Physical Properties
Bulk density:
In a 100 ml mescylinder, 100 g of a sample is charged and the mescylinderis shocked until finding no volumetric variation. The bulk density is calculated by the balanced volume and the weight (100 g).
Water absorption: In a glass plate having a diameter of 10 cm, 50 g of a sample is sampled and maintained at 300C in relative humidity of 50% for 14 days to measure an increased weight. The increased weight is divided by the weight (50 g) to calculate the water absorption.
Fluidity:
A time required for passing 150 g of a sample through a glass funnel having a tube having an inner diameter of 4.5 mm.
Table 1
Sodium carbonate
Sodium carbonate monohydrate
Mesh ,a monohydrate obtained by elec
obtained by Solvay trolyzed solution
soda process by diaphragm
electrolysis of NaC1 wt.% wt.%
+20 +840 0.1 2.4 20-24 840-710 0.5 9.0 24-28 710-590 3.1 14.1 28-35 590-420 19.5 33.8 35-70 420-210 62.5 32.3 70-100 210-149 10.3 5.0 100-145 149-105 2.8 2.0 145-300 105-46 1.0 1.1
> 300 < 46 0.2 0.3
Average particle
diameter 240 350
Table 2
Example Exp. 1 Exp.2 Exp.3 Exp.4 Exp.5 Exp.6
Condition for transition::
NaC1 concentration mother liquor (wt.%) 14 20 20 16 16 10
Na2SO4 concentration in mother 0 0 0 0 0 0 liquor (wt.%)
Temperature in crystallization 106 103 105 105 107 106 vessel ("C) Difference from transition temper- 4.5 4 6 4 6 3 ature (OC) Physical properties of anhydrous sodium carbonate:
Bulk density 1.59 1.52 1.51 1.60 1.55 1.45
Water absorption (%) 1.3 1.5 1.6 1.4 1.3 2.0
Fluidity (sec.) 18.1 18.0 18.0 17.5 16.9 20.5
Shape of crystals Sp. Sp. Sp. Sp. Sp. Sp.
Table 2 (cont'd) Exampleorreference Exp.8 Exp.9 Exp.10 Exp.11 Ref.1 Ref.2 Condition for transition: NaC1 concentration mother liquor (wt.%) 14 14 14 14 23 9
Na2SO4 concentration in mother 0.2 0.05 0.1 0.5 0 0 liquor (wt.%)
Temperature in crystallization 106 106 106 106 103 105 vessel ("C) Difference from transition temper- 4.5 4.5 4.5 4.5 5 1.5
Physical properties of an hydros sodium carbonate:
Bulk density 1.41 1.55 1.48 1.20 -
Water absorption (%) 1.9 1.4 1.5 5.5 -
Fluidity (sec.) 19.7 18.3 18.0 29.0 -
Shape of crystals Sp-fl. Sp. Sp. . Fl. Ag. Inc.
Table 2 (cont'd)
Reference Ref. 3 Ref. 4 Ref. 5 Ref. 6 Ref. 7 Ref. 8
Condition for
transition: NaC1 concentration
mother liquor (wt.%) 22 20 20 16 12
Na2SO4 concentra
tion in mother 0 0 0 0 0
liquor (wt.%) Temperature in
crystallization 106 107 101 103 105
vessel ("C) Difference from
transition temper- 8 8 2 2 2.5
ature ("C) Physical properties
of anhydrous sodium
carbonate
Bulk density 1.35 1.39 1.32 1.35 1.44 1.29
Water absorption (%) 3.8 3.4 3.4 2.9 2.2 7.8
Fluidity (sec.) 21.5 20.2 24.0 21.0 22.5 23.0
Shape of crystals Ag. Ag. Fl. Fl. Fl.
Sp.: spherical crystals
Sp-fl.: slightly flat crystals
Fl.: many flat crystals
AG.: many irregular agglomerates
Inc.: incomplete anhydrous crystallization
Claims (14)
1. A process for producing anhydrous sodium carbonate which comprises converting sodium carbonate monohydrate into anhydrous sodium carbonate by a transition in a saturated aqueous solution of sodium carbonate containing from 10 to 22 wt.% of sodium chloride which is heated at a temperature of from 3 to 7"C higher than its transition temperature.
2. A process according to claim 1, wherein the saturated aqueous solution of sodium carbonat containing sodium chloride contains not more than 0.2 wt.% of sodium sulphate.
3. A process according to claim 1 or claim 2, wherein the sodium carbonate monohydrate used is obtained by a hydration of light soda ash produced by baking sodium bicarbonate obtained by Solvay process and/or an ammonium chloride soda process.
4. A process according to claim 1 or claim 2, wherein the sodium carbonate monohydrate used is obtained by carbonation of sodium hydroxide.
5. A process according to claim 1 or claim 2, wherein the sodium carbonate monohydrate is fed to the solution in the form of a slurry.
6. A process according to claim 5, wherein the slurry of sodium carbonate monohydrate is obtained by carbonation with carbon dioxide gas or sodium bicarbonate of an electrolyzed solution obtained by a diaphragm electrolysis of sodium chloride.
7. A process according to any one of claims 1 to 4, wherein sodium carbonate monohydrate is fed in a form of solid into said unsaturated aqueous solution.
8. A process according to any preceding claim, wherein anhydrous sodium carbonate obtained by the conversion is separated from its mother liquor while maintaining the temperature of the slurry of anhydrous sodium carbonate above the transition temperature of anhydrous sodium carbonate.
9. A process according to any preceding claim, wherein separation of anhydrous sodium carbonate from its mother liquor is carried out by a centrifugal separation.
10. A process according to any preceding claim, wherein anhydrous sodium carbonate separated from its mother liquor is washed with water or an aqueous solution of sodium carbonate by spraying it during a centrifugal separation from the washing solution.
11. A process according to any preceding claim, wherein a mother liquor containing sodium carbonate and sodium chloride separated from the anhydrous sodium carbonate product is reused.
12. A process according to any preceding claim, wherein the temperature in the transition is from (110.4 0.42 x) C to (114.4 - 0.42 x) C, wherein x designates the concentration of sodium chloride by weight in the crystallization vessel.
13. A process according to claim 1 substantially as herein described with reference to the Examples.
14. Anhydrous sodium carbonate made by a process according to any preceding claim.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7853978A JPS557530A (en) | 1978-06-30 | 1978-06-30 | Manufacture of anhydrous sodium carbonate |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2024187A true GB2024187A (en) | 1980-01-09 |
| GB2024187B GB2024187B (en) | 1982-07-21 |
Family
ID=13664708
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7922190A Expired GB2024187B (en) | 1978-06-30 | 1979-06-26 | Process for producing anhydrous sodium carbonate |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS557530A (en) |
| BE (1) | BE877106A (en) |
| DE (1) | DE2926380A1 (en) |
| FR (1) | FR2429749A1 (en) |
| GB (1) | GB2024187B (en) |
| IT (1) | IT1121968B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2475067A1 (en) * | 1980-02-01 | 1981-08-07 | Asahi Glass Co Ltd | PROCESS FOR THE PREPARATION OF ANHYDROUS SODIUM CARBONATE CRYSTAL |
| US4406869A (en) * | 1980-02-04 | 1983-09-27 | Asahi Glass Company Ltd. | Process for producing anhydrous sodium carbonate crystal |
| FR2576589A1 (en) * | 1985-01-30 | 1986-08-01 | Solvay | PROCESS FOR THE MANUFACTURE OF DENSE ANHYDROUS SODIUM CARBONATE AND DENSE ANHYDROUS SODIUM CARBONATE OBTAINED BY THIS PROCESS |
| CN103998378A (en) * | 2011-12-09 | 2014-08-20 | 默克专利股份有限公司 | Anhydrous sodium carbonate with few pores |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5756318A (en) * | 1980-09-19 | 1982-04-03 | Asahi Glass Co Ltd | Manufacture of dense ash |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2133455A (en) * | 1935-05-07 | 1938-10-18 | Solvay Process Co | Production of dense soda asii |
| DE1076651B (en) * | 1958-10-09 | 1960-03-03 | Chem Fab Kalk Ges Mit Beschrae | Process for the production of a coarsely crystalline and abrasion-resistant sodium carbonate |
-
1978
- 1978-06-30 JP JP7853978A patent/JPS557530A/en active Granted
-
1979
- 1979-06-20 BE BE0/195843A patent/BE877106A/en not_active IP Right Cessation
- 1979-06-20 FR FR7915822A patent/FR2429749A1/en active Pending
- 1979-06-26 GB GB7922190A patent/GB2024187B/en not_active Expired
- 1979-06-29 DE DE19792926380 patent/DE2926380A1/en active Granted
- 1979-06-29 IT IT23987/79A patent/IT1121968B/en active
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2475067A1 (en) * | 1980-02-01 | 1981-08-07 | Asahi Glass Co Ltd | PROCESS FOR THE PREPARATION OF ANHYDROUS SODIUM CARBONATE CRYSTAL |
| US4405592A (en) * | 1980-02-01 | 1983-09-20 | Asahi Glass Company Ltd. | Process for producing anhydrous sodium carbonate crystal |
| US4406869A (en) * | 1980-02-04 | 1983-09-27 | Asahi Glass Company Ltd. | Process for producing anhydrous sodium carbonate crystal |
| FR2576589A1 (en) * | 1985-01-30 | 1986-08-01 | Solvay | PROCESS FOR THE MANUFACTURE OF DENSE ANHYDROUS SODIUM CARBONATE AND DENSE ANHYDROUS SODIUM CARBONATE OBTAINED BY THIS PROCESS |
| EP0191512A1 (en) * | 1985-01-30 | 1986-08-20 | SOLVAY & Cie (Société Anonyme) | Process for the manufacture of dense anhydrous sodium carbonate, and dense anhydrous sodium carbonate obtained by this process |
| CN103998378A (en) * | 2011-12-09 | 2014-08-20 | 默克专利股份有限公司 | Anhydrous sodium carbonate with few pores |
| US20140336273A1 (en) * | 2011-12-09 | 2014-11-13 | Merck Patent Gmbh | Anhydrous sodium carbonate having a low pore content |
| US9388053B2 (en) | 2011-12-09 | 2016-07-12 | Merck Patent Gmbh | Anhydrous sodium carbonate having a low pore content |
| CN103998378B (en) * | 2011-12-09 | 2016-12-14 | 默克专利股份有限公司 | The natrium carbonicum calcinatum of low porosity |
Also Published As
| Publication number | Publication date |
|---|---|
| DE2926380C2 (en) | 1988-03-10 |
| JPS557530A (en) | 1980-01-19 |
| JPS616010B2 (en) | 1986-02-22 |
| IT7923987A0 (en) | 1979-06-29 |
| DE2926380A1 (en) | 1980-01-10 |
| BE877106A (en) | 1979-12-20 |
| GB2024187B (en) | 1982-07-21 |
| IT1121968B (en) | 1986-04-23 |
| FR2429749A1 (en) | 1980-01-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |