CA1093277A - Process of producing aqueous solution of magnesium chloride - Google Patents
Process of producing aqueous solution of magnesium chlorideInfo
- Publication number
- CA1093277A CA1093277A CA247,230A CA247230A CA1093277A CA 1093277 A CA1093277 A CA 1093277A CA 247230 A CA247230 A CA 247230A CA 1093277 A CA1093277 A CA 1093277A
- Authority
- CA
- Canada
- Prior art keywords
- magnesium chloride
- mgo
- calcium chloride
- chloride
- magnesium
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F5/00—Compounds of magnesium
- C01F5/02—Magnesia
- C01F5/06—Magnesia by thermal decomposition of magnesium compounds
- C01F5/10—Magnesia by thermal decomposition of magnesium compounds by thermal decomposition of magnesium chloride with water vapour
Landscapes
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Inorganic Chemistry (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A process is disclosed for reducing the calcium chloride content of an aqueous solution containing 220 to 320 g/l of magnesium chloride and more than 6% by weight of calcium chloride, based on the magnesium chloride.
In the process, the aqueous solution is reacted with carbon dioxide and with MgO in the form of caustic magnesia or magnesium hydroxide, and the precipitated calcium carbonate is removed. The resulting solution contains 4 to 6% by weight of calcium chloride, based on the magnesium chloride and is suitable for use in the production of MgO by thermal decomposition, particularly by spray roasting.
A process is disclosed for reducing the calcium chloride content of an aqueous solution containing 220 to 320 g/l of magnesium chloride and more than 6% by weight of calcium chloride, based on the magnesium chloride.
In the process, the aqueous solution is reacted with carbon dioxide and with MgO in the form of caustic magnesia or magnesium hydroxide, and the precipitated calcium carbonate is removed. The resulting solution contains 4 to 6% by weight of calcium chloride, based on the magnesium chloride and is suitable for use in the production of MgO by thermal decomposition, particularly by spray roasting.
Description
1093~7 This invention relates to a process of producing aqueous solutions containing 220-320 g/l magnesium chloride and having a calcium chloride content amounting to 4-6% by weight of the magnesium chloride content, for use in the production of MgO
by thermal decomposition, particularly spray roasting.
The production of synthetic magnesia, i.e. MgO, from magnesium chloride-containing aqueous solutions by thermal de-composition and particularly by spray roasting has progressively increased in importance in recent times. This is due to various reasons. One reason is the fact that the demand for pure magnesia and particularly for very pure magnesia increases steadily and that magnesia which contains 99-99.5% MgO can be produced by such a thermal decomposition whereas magnesia recovered, e.g., from contaminated magnesite by various conventional physical dressing processes, such as heavy-liquid separation and/or flotation, has a much lower MgO content. Another reason for the increasing interest in the production of magnesia by thermal decomposition is the fact that this process enables the utilization of naturally occurring brines and abraum salts or solutions which result from the dressing of MgO-containing minerals and contain magnesium chloride.
It has now been found that aqueous solutions which contain 220-320 g/l magnesium chloride and have a calcium chlor-ide content of 4-6% by weight of the magnesium chloride content are particularly suitable for the production of MgO by thermal decomposition, particularly spray roasting, e.g., in a so-called Aman reactor, and that such aqueous solutions can advantageously be produced from solutions having a certain content of calcium chloride. Thus the invention relates to a process which serves to produce aqueous solutions of the kind stated and which essen-tially resides in that an aqueous solution which contains 220-~.
320 g/l magnesium chloride and has a calcium chloride content inexcess of 6% by weight of the magnesium chloride content is re-acted with carbon dioxide and with MgO in the form of caustic magnesia or magnesium hydroxide, and the precipitated calcium carbonate together with any additional magnesium chloride is removed. In that reaction, calcium chloride is transformed into calcium carbonate, and there is dissolved - la -10~33277 from the caustic magnesia or the magnesium hydroxide Mg in form of magnesium chloride in a quantity which is proportional to the reacted Ca. The result-ing solution may be subjected to thermal decomposition, e.g., in an Aman reactor, as such or after ha~ing been concentrated. If the solutions contain 10-25 g/l calcium chloride, the thermal decomposition will result in a magnesia which is rather coarse-grained, as this is preferred. In this context, the tern "caustic magnesia" refers to a magnesia which has been obtained by heating, e.g., raw magnesite or magnesium hydroxide to a temperature of about 600-1100C.
The starting material used in the process according to the invention may consist, e.g., of a solution which has been obtained by the action of gaseouq hydrogen chloride on an aqueous slurry of raw magnesite and/or waste magnesite. In a special embodiment, the starting material consists of a solution formed by reaction of calcium chloride-containing hydrochloric acid with raw magnesite. This measure enables a utilization of the calcium chloride-containing spent washing liquors which become available in the usual process of producing magnesia in a spray reactor by a thermal decomposition of solutions that contain magnesium chloride and calcium chloride and a subsequent washing of the resulting mixture of MgO and calcium chloride. In this way, the chloride losses which are due to the removal of CaC12 from the system, can be minimized.
The invention will be described more fully with reference to the following examples.
Example 1:
Hydrochloric acid having a concentration of about 20% (19~ g HCL/l, pH below 0.1) and containing calcium chloride is fed at a rate of 1963 kg/h HCl and 118 kg/h CaC12 in 9110 kg/h H20 into a vessel which has an acid-resist-ing lining and is provided with a stirrer. The vessel is then fed with raw magnesite at a rate of 2746.2 kg/h and subsequently with caustic magnesia at a rate of 238.8 kg/h. Said raw magnesite and caustic magnesia have the 1093Z7~7 following compositions in percent:
Raw Caustic magnesite magnesia MgO 37 8 72.2 CaO 3 9 4 0 SiO2 6.9 4.6
by thermal decomposition, particularly spray roasting.
The production of synthetic magnesia, i.e. MgO, from magnesium chloride-containing aqueous solutions by thermal de-composition and particularly by spray roasting has progressively increased in importance in recent times. This is due to various reasons. One reason is the fact that the demand for pure magnesia and particularly for very pure magnesia increases steadily and that magnesia which contains 99-99.5% MgO can be produced by such a thermal decomposition whereas magnesia recovered, e.g., from contaminated magnesite by various conventional physical dressing processes, such as heavy-liquid separation and/or flotation, has a much lower MgO content. Another reason for the increasing interest in the production of magnesia by thermal decomposition is the fact that this process enables the utilization of naturally occurring brines and abraum salts or solutions which result from the dressing of MgO-containing minerals and contain magnesium chloride.
It has now been found that aqueous solutions which contain 220-320 g/l magnesium chloride and have a calcium chlor-ide content of 4-6% by weight of the magnesium chloride content are particularly suitable for the production of MgO by thermal decomposition, particularly spray roasting, e.g., in a so-called Aman reactor, and that such aqueous solutions can advantageously be produced from solutions having a certain content of calcium chloride. Thus the invention relates to a process which serves to produce aqueous solutions of the kind stated and which essen-tially resides in that an aqueous solution which contains 220-~.
320 g/l magnesium chloride and has a calcium chloride content inexcess of 6% by weight of the magnesium chloride content is re-acted with carbon dioxide and with MgO in the form of caustic magnesia or magnesium hydroxide, and the precipitated calcium carbonate together with any additional magnesium chloride is removed. In that reaction, calcium chloride is transformed into calcium carbonate, and there is dissolved - la -10~33277 from the caustic magnesia or the magnesium hydroxide Mg in form of magnesium chloride in a quantity which is proportional to the reacted Ca. The result-ing solution may be subjected to thermal decomposition, e.g., in an Aman reactor, as such or after ha~ing been concentrated. If the solutions contain 10-25 g/l calcium chloride, the thermal decomposition will result in a magnesia which is rather coarse-grained, as this is preferred. In this context, the tern "caustic magnesia" refers to a magnesia which has been obtained by heating, e.g., raw magnesite or magnesium hydroxide to a temperature of about 600-1100C.
The starting material used in the process according to the invention may consist, e.g., of a solution which has been obtained by the action of gaseouq hydrogen chloride on an aqueous slurry of raw magnesite and/or waste magnesite. In a special embodiment, the starting material consists of a solution formed by reaction of calcium chloride-containing hydrochloric acid with raw magnesite. This measure enables a utilization of the calcium chloride-containing spent washing liquors which become available in the usual process of producing magnesia in a spray reactor by a thermal decomposition of solutions that contain magnesium chloride and calcium chloride and a subsequent washing of the resulting mixture of MgO and calcium chloride. In this way, the chloride losses which are due to the removal of CaC12 from the system, can be minimized.
The invention will be described more fully with reference to the following examples.
Example 1:
Hydrochloric acid having a concentration of about 20% (19~ g HCL/l, pH below 0.1) and containing calcium chloride is fed at a rate of 1963 kg/h HCl and 118 kg/h CaC12 in 9110 kg/h H20 into a vessel which has an acid-resist-ing lining and is provided with a stirrer. The vessel is then fed with raw magnesite at a rate of 2746.2 kg/h and subsequently with caustic magnesia at a rate of 238.8 kg/h. Said raw magnesite and caustic magnesia have the 1093Z7~7 following compositions in percent:
Raw Caustic magnesite magnesia MgO 37 8 72.2 CaO 3 9 4 0 SiO2 6.9 4.6
2 3 3.5 3 0 A1203 1.O 1.O
Mn304 0.1 0.1 Cr203 0.1 0.1 Ignition loss 46.7 15.0 The pH-value is increased above 1 by the addition of the raw magnesite, and to 5-6 by the subsequent addition of the caustic magnesia. In a batch process, the raw magnesite and the caustic magnesia are dissolved at a temperature of 80-85C in about 2 hours. At the same time, a mixture of air and chlorine gas is introduced to oxidize the ferrous compounds pre-sent to ferric compounds so that the hydroxides of iron, aluminium and manganese (sesquioxides) are precîpitated.
The reaction results in a solution which contains magnesium chloride and calcium chloride as well as insoluble matter, including the precipitated hydroxide~ or sesquioxides respectively. This solution is transferred from the dissolving vessel into a second vessel, in which calcium carbonate is to be precipitated. The transfer is effected at a rate of 2365 kg/h mgC12, 345 kg/h CaC12 and 558 kg/h insoluble matter in 9594 kg/h H20. C02 formed as a result of the dissolving of the raw magnesite, is simultaneously fed from the dissolving vessel into the second vessel at a rate of 1328 kg/h.
Alternatively, C02 in the form of combustion gases may be used. MgO in the for~ of caustic magnesia which is highly contaminated with silicates is added at a rate of 83 kg/h MgO (83 kg/h insoluble matter) to the solution then con-tained in the second vessel. The reaction in the second vessel takes about one hour. The action of carbon dioxide and caustic magnesia in the second vessel results in the precipitation of calcium carbonate at a rate of 208 kg/h. This calcium carbonate is withdrawn together with insoluble matter, which amounts to 641 kg/h and includes sesquioxides. C02 becomes available in the second vessel at a rate of 1281 kg/h.
The solution obtained in this second vessel is transferred at a rate of 2563 kg/h MgC12 and 118 kg/h CaC12 in 9594 kg/h H O into a spray roasting reactor, in which the thennal decomposition is effected at a temp-erature of 700-900C. HCl at a rate of 1963 kg/h, water at a rate of 9110 kg/h, and as end product 1083 kg/h MgO with 118 kg/h CaCl can be withdrawn from the reactor. The MgO can be freed from the calcium chloride by being washed with water, and the resulting spent washing liquor may be re-used in the process if this is desired. The hydrochloric acid recovered in the spray reactor may be used in the dissolving vessel to dissolve new material and, if desired, may previously be absorbed in that CaC12-containing spent washing liquor.
Ex~mple 2_ 11,0?3 kg hydrochloric acid having a concentration of about 20 %
(pH below 1, 1963 kg HCl, 9110 kg H O) are fed into a vessel which has an acid-resistinglining and is provided with a stirrer. 2746.2 kg raw magnesite and thereafter 238.8 kg caustic magnesia are then added to the hydrochloric acid. The raw magnesite and the caustic magnesia have the respective com-positions stated in Example 1.
The pH-value of the hydrochloric acid is increased to 1.1 by the addition of the raw magnesite and to 5.3 by the subsequent addition of caustic magnesia. The temperature at the reaction is 80-85 C. During the feeding of the caustic magnesia, simultaneously a mixture of air and chlorine gas is fed into the vessel, so that the sesquioxides are precipitated.
The solution obtained in the dissol~ing vessel contains 2365 kg MgC12, 231 kg CaC12, and 558 kg insoluble matter and sesquioxides in 9594 kg B ~ha~e~/
H20 and is ~*h~ into a second vessel, in which calcium carbonate is to be precipitated and which is fed at the same time with 1328 kg C02 from the dis-solving vessel. The feeding of 82 kg caustic magnesia, which contains 41 kg insoluble matter and sesquioxides, into the second vessel results in a preci-pitation of 101 kg calcium carbonate within about 1 hour. This calcium car-bonate is withdrawn together with 599 kg insoluble matter and sesquioxides.
A solution of 2462 kg MgC12 and 118 kg CaC12 in 9594 kg H20 is withdrawn from the second vessel and is transferred into a spray roasting reactor, in which a thermal decomposition is effected at a temperature of 700-900 C. 1888 kg HCl, 9110 kg water, and an end product consisting of a mixture of 1041 kg MgO and 118 kg CaC12 are withdrawn from the reactor.
Mn304 0.1 0.1 Cr203 0.1 0.1 Ignition loss 46.7 15.0 The pH-value is increased above 1 by the addition of the raw magnesite, and to 5-6 by the subsequent addition of the caustic magnesia. In a batch process, the raw magnesite and the caustic magnesia are dissolved at a temperature of 80-85C in about 2 hours. At the same time, a mixture of air and chlorine gas is introduced to oxidize the ferrous compounds pre-sent to ferric compounds so that the hydroxides of iron, aluminium and manganese (sesquioxides) are precîpitated.
The reaction results in a solution which contains magnesium chloride and calcium chloride as well as insoluble matter, including the precipitated hydroxide~ or sesquioxides respectively. This solution is transferred from the dissolving vessel into a second vessel, in which calcium carbonate is to be precipitated. The transfer is effected at a rate of 2365 kg/h mgC12, 345 kg/h CaC12 and 558 kg/h insoluble matter in 9594 kg/h H20. C02 formed as a result of the dissolving of the raw magnesite, is simultaneously fed from the dissolving vessel into the second vessel at a rate of 1328 kg/h.
Alternatively, C02 in the form of combustion gases may be used. MgO in the for~ of caustic magnesia which is highly contaminated with silicates is added at a rate of 83 kg/h MgO (83 kg/h insoluble matter) to the solution then con-tained in the second vessel. The reaction in the second vessel takes about one hour. The action of carbon dioxide and caustic magnesia in the second vessel results in the precipitation of calcium carbonate at a rate of 208 kg/h. This calcium carbonate is withdrawn together with insoluble matter, which amounts to 641 kg/h and includes sesquioxides. C02 becomes available in the second vessel at a rate of 1281 kg/h.
The solution obtained in this second vessel is transferred at a rate of 2563 kg/h MgC12 and 118 kg/h CaC12 in 9594 kg/h H O into a spray roasting reactor, in which the thennal decomposition is effected at a temp-erature of 700-900C. HCl at a rate of 1963 kg/h, water at a rate of 9110 kg/h, and as end product 1083 kg/h MgO with 118 kg/h CaCl can be withdrawn from the reactor. The MgO can be freed from the calcium chloride by being washed with water, and the resulting spent washing liquor may be re-used in the process if this is desired. The hydrochloric acid recovered in the spray reactor may be used in the dissolving vessel to dissolve new material and, if desired, may previously be absorbed in that CaC12-containing spent washing liquor.
Ex~mple 2_ 11,0?3 kg hydrochloric acid having a concentration of about 20 %
(pH below 1, 1963 kg HCl, 9110 kg H O) are fed into a vessel which has an acid-resistinglining and is provided with a stirrer. 2746.2 kg raw magnesite and thereafter 238.8 kg caustic magnesia are then added to the hydrochloric acid. The raw magnesite and the caustic magnesia have the respective com-positions stated in Example 1.
The pH-value of the hydrochloric acid is increased to 1.1 by the addition of the raw magnesite and to 5.3 by the subsequent addition of caustic magnesia. The temperature at the reaction is 80-85 C. During the feeding of the caustic magnesia, simultaneously a mixture of air and chlorine gas is fed into the vessel, so that the sesquioxides are precipitated.
The solution obtained in the dissol~ing vessel contains 2365 kg MgC12, 231 kg CaC12, and 558 kg insoluble matter and sesquioxides in 9594 kg B ~ha~e~/
H20 and is ~*h~ into a second vessel, in which calcium carbonate is to be precipitated and which is fed at the same time with 1328 kg C02 from the dis-solving vessel. The feeding of 82 kg caustic magnesia, which contains 41 kg insoluble matter and sesquioxides, into the second vessel results in a preci-pitation of 101 kg calcium carbonate within about 1 hour. This calcium car-bonate is withdrawn together with 599 kg insoluble matter and sesquioxides.
A solution of 2462 kg MgC12 and 118 kg CaC12 in 9594 kg H20 is withdrawn from the second vessel and is transferred into a spray roasting reactor, in which a thermal decomposition is effected at a temperature of 700-900 C. 1888 kg HCl, 9110 kg water, and an end product consisting of a mixture of 1041 kg MgO and 118 kg CaC12 are withdrawn from the reactor.
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process of producing aqueous solutions containing at least 220 g/l magnesium chloride and having a calcium chloride content amounting to 4-6% by weight of the magnesium chloride content, for use in the production of MgO by thermal decompo-sition, particularly spray roasting, wherein an aqueous solu-tion which contains about 220-320 g/l magnesium chloride and has a calcium chloride content in excess of 6% by weight of the magnesium chloride content is reacted with carbon dioxide and with MgO in the form of caustic magnesia or magnesium hydroxide, and the precipitated calcium carbonate is removed.
2. A process according to claim 1 wherein the starting material consists of a solution which has been obtained by the action of gaseous hydrogen chloride on an aqueous slurry of a material selected from raw magnesite, waste magnesite, and mixtures thereof.
3. A process according to claim 1 wherein the starting material consists of a solution formed by reaction of calcium chloride-containing hydrochloric acid with raw magnesite.
4. A process according to any of claims 1 to 3 wherein carbon dioxide is used which has been formed as a result of the dissolving of raw magnesite in hydrochloric acid.
5. A process according to claim 1 wherein carbon dioxide contained in combustion gases is used.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ATA1890/75 | 1975-03-12 | ||
| AT189075A AT335973B (en) | 1975-03-12 | 1975-03-12 | PROCESS FOR THE PREPARATION OF AQUATIC SOLUTIONS OF MAGNESIUM CHLORIDE |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1093277A true CA1093277A (en) | 1981-01-13 |
Family
ID=3523226
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA247,230A Expired CA1093277A (en) | 1975-03-12 | 1976-03-05 | Process of producing aqueous solution of magnesium chloride |
Country Status (7)
| Country | Link |
|---|---|
| AT (1) | AT335973B (en) |
| AU (1) | AU501146B2 (en) |
| BR (1) | BR7601483A (en) |
| CA (1) | CA1093277A (en) |
| DE (1) | DE2608617A1 (en) |
| ES (1) | ES445970A1 (en) |
| IL (1) | IL49163A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5286285A (en) * | 1989-05-05 | 1994-02-15 | Veitscher Magnesitwerke-Actien-Gesellschaft | Finely powdery magnesium hydroxide and a process for preparing thereof |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT367376B (en) * | 1979-12-06 | 1982-06-25 | Veitscher Magnesitwerke Ag | METHOD FOR SEPARATING IRON, ALUMINUM AND MANGANE IMPURITIES FROM SALT ACID MAGNESIUM CHLORIDE SOLUTIONS |
| AT392774B (en) * | 1989-05-05 | 1991-06-10 | Veitscher Magnesitwerke Ag | FINE POWDERED MAGNESIUM HYDROXIDE AND METHOD FOR THE PRODUCTION THEREOF |
-
1975
- 1975-03-12 AT AT189075A patent/AT335973B/en not_active IP Right Cessation
-
1976
- 1976-03-02 DE DE19762608617 patent/DE2608617A1/en active Pending
- 1976-03-05 CA CA247,230A patent/CA1093277A/en not_active Expired
- 1976-03-05 IL IL49163A patent/IL49163A/en unknown
- 1976-03-08 AU AU11754/76A patent/AU501146B2/en not_active Expired
- 1976-03-11 BR BR7601483A patent/BR7601483A/en unknown
- 1976-03-11 ES ES445970A patent/ES445970A1/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5286285A (en) * | 1989-05-05 | 1994-02-15 | Veitscher Magnesitwerke-Actien-Gesellschaft | Finely powdery magnesium hydroxide and a process for preparing thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| AU1175476A (en) | 1977-09-15 |
| IL49163A0 (en) | 1976-05-31 |
| IL49163A (en) | 1979-11-30 |
| ATA189075A (en) | 1976-08-15 |
| AU501146B2 (en) | 1979-06-14 |
| ES445970A1 (en) | 1977-07-01 |
| AT335973B (en) | 1977-04-12 |
| BR7601483A (en) | 1976-09-14 |
| DE2608617A1 (en) | 1976-09-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |