US3226311A - Process of producing calcium by electrolysis - Google Patents
Process of producing calcium by electrolysis Download PDFInfo
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- US3226311A US3226311A US283694A US28369463A US3226311A US 3226311 A US3226311 A US 3226311A US 283694 A US283694 A US 283694A US 28369463 A US28369463 A US 28369463A US 3226311 A US3226311 A US 3226311A
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- calcium
- electrolysis
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- chloride
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- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 title claims description 44
- 229910052791 calcium Inorganic materials 0.000 title claims description 44
- 239000011575 calcium Substances 0.000 title claims description 44
- 238000000034 method Methods 0.000 title claims description 34
- 238000005868 electrolysis reaction Methods 0.000 title claims description 33
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 claims description 16
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 claims description 10
- WDIHJSXYQDMJHN-UHFFFAOYSA-L barium chloride Chemical compound [Cl-].[Cl-].[Ba+2] WDIHJSXYQDMJHN-UHFFFAOYSA-L 0.000 claims description 10
- 229910001626 barium chloride Inorganic materials 0.000 claims description 10
- 239000001110 calcium chloride Substances 0.000 claims description 10
- 229910001628 calcium chloride Inorganic materials 0.000 claims description 10
- 229910001631 strontium chloride Inorganic materials 0.000 claims description 10
- AHBGXTDRMVNFER-UHFFFAOYSA-L strontium dichloride Chemical compound [Cl-].[Cl-].[Sr+2] AHBGXTDRMVNFER-UHFFFAOYSA-L 0.000 claims description 10
- 239000001103 potassium chloride Substances 0.000 claims description 8
- 235000011164 potassium chloride Nutrition 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 4
- 230000008018 melting Effects 0.000 claims description 4
- 238000002844 melting Methods 0.000 claims description 4
- 150000003839 salts Chemical class 0.000 description 20
- 229910052751 metal Inorganic materials 0.000 description 16
- 239000002184 metal Substances 0.000 description 16
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 8
- 239000000460 chlorine Substances 0.000 description 8
- 229910052801 chlorine Inorganic materials 0.000 description 8
- 101100496858 Mus musculus Colec12 gene Proteins 0.000 description 6
- 239000007787 solid Substances 0.000 description 6
- 229910001295 No alloy Inorganic materials 0.000 description 5
- 238000002360 preparation method Methods 0.000 description 5
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 4
- 150000001342 alkaline earth metals Chemical class 0.000 description 4
- 229910000882 Ca alloy Inorganic materials 0.000 description 3
- 210000004027 cell Anatomy 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 150000002739 metals Chemical class 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 229910052788 barium Inorganic materials 0.000 description 2
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 2
- 229910001634 calcium fluoride Inorganic materials 0.000 description 2
- 150000001805 chlorine compounds Chemical class 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 2
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 229910052712 strontium Inorganic materials 0.000 description 2
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000004581 coalescence Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 210000001787 dendrite Anatomy 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 150000001455 metallic ions Chemical class 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
- C25C3/02—Electrolytic production, recovery or refining of metals by electrolysis of melts of alkali or alkaline earth metals
Definitions
- the present invention relates to a new process for the preparation of calcium by electrolysis of baths of fused salts, and it is also concerned with a process for preparing alloys of calcium with metals which are less noble from the electrochemical point of view.
- the usual process for the preparation of calcium by electrolysis in the fused state is the process which produces calcium rods.
- the calcium is deposited in the liquid state at the cathode and solidifies as it is extracted from the bath of fused salts in the form of a rod or core.
- the conditions necessary for good formation of the core are extremely critical.
- the electrolysis of calcium chloride requires, under these conditions, a voltage in the region of volts and a cathode current density which is very high, e.g. above 100 amperes per square centimeter.
- the chloride admixed with chlorides of strontium and barium in the proportions of 20 to 80 mol percent of calcium chloride, 5 to 45 mol percent of strontium chloride and 5 to mol percent of barium chloride.
- the bath can also contain 0 to 35 mol percent of potassium chloride.
- the proportions are to 75 mol percent of calcium chloride, 15 to 35 mol percent of strontium chloride, and 15 to 30 mol percent of barium chloride and, when potassium chloride is used, at least 10 mol percent of this salt is preferably present, with at least 25 mol percent being particularly preferred.
- Electrolysis is carried out at a temperature of 650 to 750 C. and the calcium is produced in the solid state and in a very pure form at the cathode.
- a cathode preferably rotating, constituted by a metal which forms no alloy with calcium.
- it is possible to render the process continuous by arranging a doctor blade at the cathode which removes the calcium deposited.
- the process forming the object of the invention is therefore characterized by the fact that one subjects to electrolysis a bath of fused salts which comprises, besides the chloride of calcium, at least strontium chloride and barium chloride, and preferably also potassium chloride, in the proportions indicated at a temperature between 650 and 750 C. and under a voltage of 5-7 volts, the calcium being obtained directly in the solid compact state on a rotating cathode of a metal which forms no alloy with calcium. Further characteristics of the invention become apparent from the following.
- the metallic ions which may constitute the bath of fused salts sodium, being slightly more noble from the electrochemical point of view than the alkaline earth metals, is suitably present as an ion in small quantities, e.g. 5 to 15%. Furthermore, it goes without saying that the process proposed makes it possible to obtain alloys of calcium with metals more noble than they are, that is to say, of alkali metals, by a judicious choice of the constituents of the baths of fused salts.
- the advantages of the new process are many, above all by reason of the decrease of the temperature at which one operates.
- the power required for obtaining and maintaining the salt bath at the electrolysis temperature is reduced.
- the corrosion of the material of construction of the cell is reduced and, in consequence, the life of the latter is prolonged.
- the solubility of the metal in the bath is further reduced, which avoids losses by redissolving of the metal, and likewise losses by vaporization of the metal are avoided because of the reduction of its volatility.
- the process permits operation with voltages in the region of 5 to 7 volts instead of 25 volts and the power consumption expressed in kilowatt hours per kilogram of alkaline earth metal produced is reduced to one-fifth of the consumption observed in the usual process.
- the process permits operation at relatively high current intensities, e.g. amperes. This is a particularly important advantage since operation at such current intensities with processes of the prior art have involved a serious sacrifice of efiiciency. High current intensities permit, of course, a greater production for a given apparatus.
- the new process is carried out in a cell constituted by a vessel made of generally impermeable refractory material serving to contain the bath of fused salts, a graphite anode and a cathode made of a metal which forms no alloy with calcium.
- the process is preferably carried out in an apparatus such as that described in Belgian Patent 578,670 under the title Process for the Preparation of Alkaline Earth Metals and of Alloys Based on Alkaline Earth Metals by Electrolysis of Baths of Fused Salts, wherein the anode is of an annular form and a screen of insulating and impermeable material imposes a non-linear course on the current lines between the electrodes.
- the cathode slowly turns, for example at 50 revolutions per minute, which avoids the formation of metal in the form of dendrites and favors the coalescence of the metallic deposit on the cathode.
- the metal collected is compact and homogeneous.
- the new process enables the calcium to be obtained in a very pure form, the degree of purity being above 96%.
- the oxygen content of the product obtained is much smaller than that of the product obtained by the rod or core process.
- the yield is further improved by subjecting the baths of fused salts to a previous purification for the purpose of removing all traces of water and oxygen.
- hydrogen chloride in the dry state or chlorine is bubbled into the bath of fused salts.
- This treatment may be advantageously combined with a pre-electrolysis under reduced voltage for example of 2 to 3 volts.
- Another feature of the present invention is the possibility of preparing alloys of calcium with metals which are more noble from the electrochemical point of view.
- a cathode is used which is made of the metal which it is desired to be alloyed with the calcium.
- alloys by using a cathode formed of magnesium, aluminum, silver, copper, gold, etc.
- compositions permit an operation at a temperature below 700 C. comprised between 660 and 680 C.
- Example 1 There is subjected to electrolysis a bath of fused salts comprising 60 gram mol percent calcium choride, 20 gram mol percent strontium chloride, and 20 gram mol percent barium chloride previously purified by treatment with dry hydrogen chloride gas or chlorine.
- a small quantity of alumina (A1 e.g. up to 3% by Weight of the bath, preferably at least 0.2% is added in powder form to improve the stability of the electrolysis.
- the bath temperature is maintained at 676 C. and, in the presence of a stainless steel cathode rotating at 50 revolutions per minute, electrolysis is carried out under a voltage of 5.33 volts.
- the cathode current density is 2 amperes per square centimeter.
- Example 2 At a temperature of 670 C. a bath of fused salts is subjected to electrolysis, formed by 25 gram mol percent calcium chloride, 25 gram mol percent strontium chloride, 25 gram mol percent barium chloride and 25 gram mol percent potassium chloride at a voltage of 5.29 volts and an anode current density of 2 amperes per square centimeter.
- Calcium is obtained in a solid homogeneous and compact state with an anode current efficiency of 79%.
- the power consumption is 9 kilowatt hours per kilogram of calcium.
- Example 3 Example 1 is repeated but working at 660 C. and with a current density of 2.5 amperes per square centimeter. Calcium is obtained in more than 96% purity with a power consumption of 9 kilowatt hours per kilogram of calcium.
- Example 14 A bath containing 50 gram mol percent of CaCl 15 gram mol percent of SrCl and 35 gram mol percent of BaCl at a temperature of 720 C. was submitted to electrolysis under a voltage of 5.05 volts and a current of 20 amperes. The current efficiency both for chlorine and calcium was 95 percent.
- Example 15 A bath containing 60 gram mol percent of CaC1 20 gram mol percent of BaCl 20 gram mol percent of SrCl and 3 weight percent of A1 0 was submitted to electrolysis at 670 C. under a voltage of 5.10 volts and a current of 12 amperes. The current efficiency both for chlorine and calcium was 98 percent.
- a process for the production of calcium metal by electrolysis of a bath of fused chlorides at a temperature lower than the melting point of calcium which comprises subjecting to electrolysis a bath comprising 20 to 80 mol percent of calcium chloride, 5 to 45 mol percent of strontium chloride, 5 to 35 mol percent of barium chloride and 0 to 35 mol percent of potassium chloride, said electrolysis being carried out at a temperature between 650 and 750 C.
- a process for the preparation of calcium which comprises subjecting to electrolysis a bath of fused salts comprising 60 gram mol percent calcium chloride, 20 gram mol percent strontium chloride, and 20 gram mol percent barium chloride at a temperature between 660 and 680 C. and at a voltage of 5 to 7 volts, said electrolysis being carried out in the presence of a cathode of a metal which forms no alloy with calcium, the calcium being obtained directly in the solid compact state on said cathode.
- a process for the preparation of calcium which comprises subjecting to electrolysis a bath of fused salts comprising 25 gram rnol percent calcium chloride, 25 gram mol percent strontium chloride, 25 gram rnol percent barium chloride and 25 gram mol percent potassium chloride at a temperature between 660 and 680 C. and at a voltage of 5 to 7 volts, said electrolysis being carried out in the presence of a cathode of a metal which forms no alloy with calcium, the calcium being obtained directly in the solid compact state on said cathode.
- said bath further comprises up to 3% by weight of the bath of alumina.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Electrolytic Production Of Metals (AREA)
- Manufacture And Refinement Of Metals (AREA)
Description
United States Patent 3,226,311 PROCESS 0F PRUDUCHNG CALCEUM BY ELECTRQLYSHS Jacques Van Diest, Uccle-Brussels, Beigiurn, assignor to Solvay & Cie, Uccle-Brussels, Belgium No Drawing. Filed May 28, 1963, Ser. No. 283,694
Claims priority, application Belgium, May 13, 1959, 458,486
7 Claims. (til. 204-69) This is a continuation-in-part of my copending application, Serial No. 25,530 filed April 29, 1960, and now abandoned.
The present invention relates to a new process for the preparation of calcium by electrolysis of baths of fused salts, and it is also concerned with a process for preparing alloys of calcium with metals which are less noble from the electrochemical point of view.
The usual process for the preparation of calcium by electrolysis in the fused state is the process which produces calcium rods. In this process, the calcium is deposited in the liquid state at the cathode and solidifies as it is extracted from the bath of fused salts in the form of a rod or core. The conditions necessary for good formation of the core are extremely critical. Thus, one uses a bath of fused calcium chloride in the pure state, or alloyed with a lesser quantity of calcium fluoride, and to maintain this bath in the fused state it is necessary to use temperatures of the order of 800 C. The electrolysis of calcium chloride requires, under these conditions, a voltage in the region of volts and a cathode current density which is very high, e.g. above 100 amperes per square centimeter. The disadvantages of such a process are apparent; it requires a high consumption of power not only for the electrolysis proper, but also to obtain and maintain the bath of salts in the fused state. This consumption is of the order of 50 kilowatt per kilogram of calcium product. Moreover, the elevated temperatures required for carrying out the process lead to considerable corrosion of the materials of construction of the cell and reduce the life of the latter. Furthermore, chlorine is obtained at the anode in a very diluted state and, finally, the process is essentially discontinuous and requires considerable labor.
I have now discovered that it is possible to obtain calcium in a pure state by the electrolysis of baths of fused salts and under conditions of current efficiency and power consumption which are extremely advantageous.
I have established the surprising fact that by using as baths of fused salts, rather than the chloride of calcium alone or admixed with a little calcium fluoride, the chloride admixed with chlorides of strontium and barium in the proportions of 20 to 80 mol percent of calcium chloride, 5 to 45 mol percent of strontium chloride and 5 to mol percent of barium chloride. The bath can also contain 0 to 35 mol percent of potassium chloride. Preferably the proportions are to 75 mol percent of calcium chloride, 15 to 35 mol percent of strontium chloride, and 15 to 30 mol percent of barium chloride and, when potassium chloride is used, at least 10 mol percent of this salt is preferably present, with at least 25 mol percent being particularly preferred. Electrolysis is carried out at a temperature of 650 to 750 C. and the calcium is produced in the solid state and in a very pure form at the cathode. One thus obtains directly the calcium in a compact form by operating in the presence of a cathode, preferably rotating, constituted by a metal which forms no alloy with calcium. Moreover, it is possible to render the process continuous by arranging a doctor blade at the cathode which removes the calcium deposited.
The process forming the object of the invention is therefore characterized by the fact that one subjects to electrolysis a bath of fused salts which comprises, besides the chloride of calcium, at least strontium chloride and barium chloride, and preferably also potassium chloride, in the proportions indicated at a temperature between 650 and 750 C. and under a voltage of 5-7 volts, the calcium being obtained directly in the solid compact state on a rotating cathode of a metal which forms no alloy with calcium. Further characteristics of the invention become apparent from the following.
Among the metallic ions which may constitute the bath of fused salts, sodium, being slightly more noble from the electrochemical point of view than the alkaline earth metals, is suitably present as an ion in small quantities, e.g. 5 to 15%. Furthermore, it goes without saying that the process proposed makes it possible to obtain alloys of calcium with metals more noble than they are, that is to say, of alkali metals, by a judicious choice of the constituents of the baths of fused salts.
The advantages of the new process are many, above all by reason of the decrease of the temperature at which one operates. Thus the power required for obtaining and maintaining the salt bath at the electrolysis temperature is reduced. The corrosion of the material of construction of the cell is reduced and, in consequence, the life of the latter is prolonged. The solubility of the metal in the bath is further reduced, which avoids losses by redissolving of the metal, and likewise losses by vaporization of the metal are avoided because of the reduction of its volatility. The process permits operation with voltages in the region of 5 to 7 volts instead of 25 volts and the power consumption expressed in kilowatt hours per kilogram of alkaline earth metal produced is reduced to one-fifth of the consumption observed in the usual process. In addition, the process permits operation at relatively high current intensities, e.g. amperes. This is a particularly important advantage since operation at such current intensities with processes of the prior art have involved a serious sacrifice of efiiciency. High current intensities permit, of course, a greater production for a given apparatus.
The new process is carried out in a cell constituted by a vessel made of generally impermeable refractory material serving to contain the bath of fused salts, a graphite anode and a cathode made of a metal which forms no alloy with calcium. The process is preferably carried out in an apparatus such as that described in Belgian Patent 578,670 under the title Process for the Preparation of Alkaline Earth Metals and of Alloys Based on Alkaline Earth Metals by Electrolysis of Baths of Fused Salts, wherein the anode is of an annular form and a screen of insulating and impermeable material imposes a non-linear course on the current lines between the electrodes. The cathode slowly turns, for example at 50 revolutions per minute, which avoids the formation of metal in the form of dendrites and favors the coalescence of the metallic deposit on the cathode. The metal collected is compact and homogeneous. By contrast to the hitherto known electrolytic processes, the new process enables the calcium to be obtained in a very pure form, the degree of purity being above 96%. The oxygen content of the product obtained is much smaller than that of the product obtained by the rod or core process.
The yield is further improved by subjecting the baths of fused salts to a previous purification for the purpose of removing all traces of water and oxygen. For this purpose, hydrogen chloride in the dry state or chlorine is bubbled into the bath of fused salts. This treatment may be advantageously combined with a pre-electrolysis under reduced voltage for example of 2 to 3 volts.
During the course of electrolysis it has been established that the current density is not critical. It may be very small without affecting the current efficiency which permits working with an extremely low power consumption.
Another feature of the present invention is the possibility of preparing alloys of calcium with metals which are more noble from the electrochemical point of view. For this purpose, a cathode is used which is made of the metal which it is desired to be alloyed with the calcium. In this way there may be obtained alloys by using a cathode formed of magnesium, aluminum, silver, copper, gold, etc.
To prepare calcium according to the present invention, fused baths of the specified composition are subjected to electrolysis. The following compositions, expressed in gram mol percent, are particularly suitable for carrying out the manufacture of calcium according to the process which forms the object of the present invention:
CaCl 60 SrCl 20 BaCI 20 CaCl 25 SrCl 25 BaCI 25 KCl: 25
These compositions permit an operation at a temperature below 700 C. comprised between 660 and 680 C.
The following examples serve to illustrate the advantages of the process forming the objects of the invention. It must be understood that they do not limit the scope of the invention which is capable of variations without departing from the invention as defined in the claims.
Example 1 There is subjected to electrolysis a bath of fused salts comprising 60 gram mol percent calcium choride, 20 gram mol percent strontium chloride, and 20 gram mol percent barium chloride previously purified by treatment with dry hydrogen chloride gas or chlorine. A small quantity of alumina (A1 e.g. up to 3% by Weight of the bath, preferably at least 0.2% is added in powder form to improve the stability of the electrolysis.
The bath temperature is maintained at 676 C. and, in the presence of a stainless steel cathode rotating at 50 revolutions per minute, electrolysis is carried out under a voltage of 5.33 volts. The cathode current density is 2 amperes per square centimeter.
At the cathode, solid calcium is collected in a compact and homogeneous form. It is brilliant in appearance and its degree of purity exceeds 96%. The impurities are principally formed by strontium and barium.
It has been found that by operating in this manner the anode current efliciency is 80% and the power consumption is 9 kilowatt hours per kilogram of calcium, instead of 50 kilowatt hours per kilogram of calcium as in the conventional process.
Example 2 At a temperature of 670 C. a bath of fused salts is subjected to electrolysis, formed by 25 gram mol percent calcium chloride, 25 gram mol percent strontium chloride, 25 gram mol percent barium chloride and 25 gram mol percent potassium chloride at a voltage of 5.29 volts and an anode current density of 2 amperes per square centimeter.
Calcium is obtained in a solid homogeneous and compact state with an anode current efficiency of 79%. The power consumption is 9 kilowatt hours per kilogram of calcium.
Example 3 Example 1 is repeated but working at 660 C. and with a current density of 2.5 amperes per square centimeter. Calcium is obtained in more than 96% purity with a power consumption of 9 kilowatt hours per kilogram of calcium.
Various other combinations of salts falling within the ranges set forth above were subjected to electrolysis at various temperatures. These additional examples of the process of this invention are set forth below. In the 4- following table, the concentrations of the salts are given in mol percent:
Example Melting Electrolysis No. CaCl SrCl BaCI K01 ppigt, temperature Example 13 A bath containing 60 gram mol percent of CaCl 20 gram mol percent of BaCl and 20 gram mol percent of SrCl and having a melting point of 608 C., was submitted to electrolysis for an hour and a half at a temperature of 675 C. There was obtained 108 g. of calcium metal of 98 percent purity. The current efiiciency both for chlorine and calcium amounted to percent.
In th table below the conditions of the foregoing example are set forth.
Current (amperes) 100 Temperature (C.) 675 Period of electrolysis (minutes) 90 Current density (amp/cm?) 8 Voltage 5.37 Ampere hours Chlorine current eificiency (percent) 95 Chlorine evolved (grams) 167 Calcium current etficiency (percent) 95 Calcium collected (grams) 106 Example 14 A bath containing 50 gram mol percent of CaCl 15 gram mol percent of SrCl and 35 gram mol percent of BaCl at a temperature of 720 C. was submitted to electrolysis under a voltage of 5.05 volts and a current of 20 amperes. The current efficiency both for chlorine and calcium was 95 percent.
Example 15 A bath containing 60 gram mol percent of CaC1 20 gram mol percent of BaCl 20 gram mol percent of SrCl and 3 weight percent of A1 0 was submitted to electrolysis at 670 C. under a voltage of 5.10 volts and a current of 12 amperes. The current efficiency both for chlorine and calcium was 98 percent.
I claim:
it. A process for the production of calcium metal by electrolysis of a bath of fused chlorides at a temperature lower than the melting point of calcium, which comprises subjecting to electrolysis a bath comprising 20 to 80 mol percent of calcium chloride, 5 to 45 mol percent of strontium chloride, 5 to 35 mol percent of barium chloride and 0 to 35 mol percent of potassium chloride, said electrolysis being carried out at a temperature between 650 and 750 C.
2. A process as defined in claim 1, wherein the bath contains 40 to 75 mol percent of calcium chloride, 15 to 35 mol percent of strontium chloride, and 15 to 30 mol percent of barium chloride.
3. A process for the preparation of calcium which comprises subjecting to electrolysis a bath of fused salts comprising 60 gram mol percent calcium chloride, 20 gram mol percent strontium chloride, and 20 gram mol percent barium chloride at a temperature between 660 and 680 C. and at a voltage of 5 to 7 volts, said electrolysis being carried out in the presence of a cathode of a metal which forms no alloy with calcium, the calcium being obtained directly in the solid compact state on said cathode.
4. A process for the preparation of calcium which comprises subjecting to electrolysis a bath of fused salts comprising 25 gram rnol percent calcium chloride, 25 gram mol percent strontium chloride, 25 gram rnol percent barium chloride and 25 gram mol percent potassium chloride at a temperature between 660 and 680 C. and at a voltage of 5 to 7 volts, said electrolysis being carried out in the presence of a cathode of a metal which forms no alloy with calcium, the calcium being obtained directly in the solid compact state on said cathode.
5. A process as defined in claim 1, wherein said bath further comprises up to 3% by weight of the bath of alumina.
6. A process as defined in claim 1 wherein during said References Cited by the Examiner UNITED STATES PATENTS 886,857 5/1908 Price et al. 204-69 2,850,442 9/1958 Cathcart et al. 204-68 3,043,756 7/1962 Cobel et al. 204-69 JOHN H. MACK, Primary Examiner. WINSTON A. DOUGLAS, Examiner.
Claims (1)
1. A PROCESS FOR THE PRODUCTION OF CALCIUM METAL BY ELECTROLYSIS OF A BATH OF FUSED CHLORIDES AT A TEMPERATURE LOWER THAN THE MELTING POINT OF CALCIUM, WHICH COMPRISES SUBJECTING TO ELECTROLYSIS A BATH COMPRISING 20 TO 80 MOL PERCENT OF CALCIUM CHLORIDE, 5 TO 45 MOL PERCENT OF STRONTIUM CHLORIDE, 5 TO 35 MOL PERCENT OF BARIUM CHLORIDE AND 0 TO 35 MOL PERCENT OF POTASSIUM CHLORIDE, SAID ELECTROLYSIS BEING CARRIED OUT AT A TEMPERATURE BETWEEN 650 AND 750*C.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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BE458486 | 1959-05-13 |
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US3226311A true US3226311A (en) | 1965-12-28 |
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ID=3844393
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---|---|---|---|
US283694A Expired - Lifetime US3226311A (en) | 1959-05-13 | 1963-05-28 | Process of producing calcium by electrolysis |
Country Status (3)
Country | Link |
---|---|
US (1) | US3226311A (en) |
ES (1) | ES257371A1 (en) |
GB (1) | GB951254A (en) |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3335076A (en) * | 1963-06-11 | 1967-08-08 | Vereintgte Deutsche Metallwerk | Process for purifying and transporting light metal |
US4738759A (en) * | 1984-10-05 | 1988-04-19 | Extramet S.A. Zone Industrielle | Method for producing calcium or calcium alloys and silicon of high purity |
US5024737A (en) * | 1989-06-09 | 1991-06-18 | The Dow Chemical Company | Process for producing a reactive metal-magnesium alloy |
US20080053838A1 (en) * | 2004-10-12 | 2008-03-06 | Toho Titanium Co., Ltd. | Method for Production of Metal by Molten-Salt Electrolysis and Method for Production of Titanium Metal |
US20080078679A1 (en) * | 2004-10-12 | 2008-04-03 | Toho Titanium Co., Ltd. | Method and Apparatus for Producing Metal by Molten-Salt Electrolysis |
EP1785509A4 (en) * | 2004-06-30 | 2008-06-25 | Toho Titanium Co Ltd | Method and apparatus for producing metal by electrolysis of molten salt |
US20090032405A1 (en) * | 2005-04-25 | 2009-02-05 | Yuichi Ono | Molten Salt Electrolytic Cell and Process for Producing Metal Using the Same |
US20090152104A1 (en) * | 2005-09-21 | 2009-06-18 | Yuichi Ono | Molten salt electrolyzer for reducing metal, method for electrolyzing the same, and process for producing refractory metal with use of reducing metal |
CN107557818A (en) * | 2017-08-22 | 2018-01-09 | 中南大学 | It is a kind of can continuous electrolysis production copper calcium alloy large scale industry electrolytic cell |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2797891A1 (en) * | 1999-08-26 | 2001-03-02 | Ind Des Poudres Spheriques | Production of calcium and its alloys involves dissolving calcium carbide in anhydrous calcium chloride, contacting obtained solution with molten metal phase, and decomposing formed alloy by physical or electrochemical refining |
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US886857A (en) * | 1906-12-29 | 1908-05-05 | Central Trust Company Of New York | Electrolytic process of producing metals. |
US2850442A (en) * | 1956-04-11 | 1958-09-02 | Du Pont | Bath for the manufacture of sodium |
US3043756A (en) * | 1958-07-31 | 1962-07-10 | Dow Chemical Co | Calcium metal production |
-
1960
- 1960-04-14 ES ES0257371A patent/ES257371A1/en not_active Expired
- 1960-05-09 GB GB16365/60A patent/GB951254A/en not_active Expired
-
1963
- 1963-05-28 US US283694A patent/US3226311A/en not_active Expired - Lifetime
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US886857A (en) * | 1906-12-29 | 1908-05-05 | Central Trust Company Of New York | Electrolytic process of producing metals. |
US2850442A (en) * | 1956-04-11 | 1958-09-02 | Du Pont | Bath for the manufacture of sodium |
US3043756A (en) * | 1958-07-31 | 1962-07-10 | Dow Chemical Co | Calcium metal production |
Cited By (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3335076A (en) * | 1963-06-11 | 1967-08-08 | Vereintgte Deutsche Metallwerk | Process for purifying and transporting light metal |
US4738759A (en) * | 1984-10-05 | 1988-04-19 | Extramet S.A. Zone Industrielle | Method for producing calcium or calcium alloys and silicon of high purity |
US5024737A (en) * | 1989-06-09 | 1991-06-18 | The Dow Chemical Company | Process for producing a reactive metal-magnesium alloy |
EP1785509A4 (en) * | 2004-06-30 | 2008-06-25 | Toho Titanium Co Ltd | Method and apparatus for producing metal by electrolysis of molten salt |
US20090211916A1 (en) * | 2004-06-30 | 2009-08-27 | Masanori Yamaguchi | Method and apparatus for producing metal by electrolysis of molton salt |
US20080053838A1 (en) * | 2004-10-12 | 2008-03-06 | Toho Titanium Co., Ltd. | Method for Production of Metal by Molten-Salt Electrolysis and Method for Production of Titanium Metal |
JPWO2006040979A1 (en) * | 2004-10-12 | 2008-05-15 | 東邦チタニウム株式会社 | Method for producing metal by molten salt electrolysis and method for producing titanium metal |
EP1808513A4 (en) * | 2004-10-12 | 2009-07-29 | Toho Titanium Co Ltd | Method for producing metal by molten salt electrolysis and method for producing metal titanium |
US20080078679A1 (en) * | 2004-10-12 | 2008-04-03 | Toho Titanium Co., Ltd. | Method and Apparatus for Producing Metal by Molten-Salt Electrolysis |
JP4602986B2 (en) * | 2004-10-12 | 2010-12-22 | 東邦チタニウム株式会社 | Method for producing metallic calcium by molten salt electrolysis |
US20090032405A1 (en) * | 2005-04-25 | 2009-02-05 | Yuichi Ono | Molten Salt Electrolytic Cell and Process for Producing Metal Using the Same |
US20090152104A1 (en) * | 2005-09-21 | 2009-06-18 | Yuichi Ono | Molten salt electrolyzer for reducing metal, method for electrolyzing the same, and process for producing refractory metal with use of reducing metal |
CN107557818A (en) * | 2017-08-22 | 2018-01-09 | 中南大学 | It is a kind of can continuous electrolysis production copper calcium alloy large scale industry electrolytic cell |
CN107557818B (en) * | 2017-08-22 | 2019-04-09 | 中南大学 | A large-scale industrial electrolytic cell capable of producing copper-calcium alloys by continuous electrolysis |
Also Published As
Publication number | Publication date |
---|---|
ES257371A1 (en) | 1960-11-16 |
GB951254A (en) | 1964-03-04 |
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