GB2045736A

GB2045736A - Preparation of magnesium chloride

Info

Publication number: GB2045736A
Application number: GB8008235A
Authority: GB
Original assignee: Nalco Chemical Co
Current assignee: ChampionX LLC
Priority date: 1979-03-21
Filing date: 1980-03-11
Publication date: 1980-11-05
Also published as: BR8001669A; CA1142324A; AU5667780A; FR2451890A1; NL8001653A; NO800803L; DE3010755A1; SE8002133L

Abstract

Anhydrous MgCl2 and KCl is recovered from carnallite mineral ore by (a) dissolving the one in the minimum amount of water required to obtain complete solubility (b) filtering out any residual precipitates (c) adding ethylene glycol to the filtrate of (b) to solubilize all MgCl2 present in the filtrate, (d) dehydrating the resultant solution of step (c) by distillation to obtain an anhydrous solution of MgCl2 in ethylene glycol and an anhydrous KCl precipitate and removing the precipitate (e) adding anhydrous NH3 to the MgCl2 solution forming MgCl2.6NH3 precipitate filtering off the precipitate, washing with a low molecular weight solvent for ethylene glycol, the solvent having previous been saturated with anhydrous NH3 and (f) heating the washed precipitate to drive off NH3. Alternatively the MgCl2 and K2SO4 are recovered by (a) dissolving a mixed double salt of Mg and K sulphates in water at 50 to 90 DEG C and filtering off the residue (b) adding KCl to the filtrate, (c) heating solution of (b) at 50 to 90 DEG C, (d) adding ethylene glycol to resultant solution from (c) to fully dissolve all MgCl2 and removing precipitated K2SO4 (e) distilling water from the solution of (d) to form an anhydrous MgCl2 solution in ethylene glycol and a precipitate of K2SO4 and removing the precipitate (f) combining the K2SO4 precipitate of steps (d) and (e) and washing with water and (g) treating the anhydrous solution of MgCl2 in ethylene glycol as in steps (e) and (f) of the first embodiment.

Description

SPECIFICATION Preparation of useful magnesium chloride The present invention relates to the preparation of magnesium chloride.

In the process of manufacturing magnesium metal, the electrolysis of anhydrous magnesium chloride in a molten salt eutectic is normally practiced. The magnesium metal is separated from the bath and electrolysis cell by flotation in molten baths that contain primarily MgCl2, KCI and NaCI along with additional CaCI2 salts. Other eutectic "mixed" salt baths used to recover magnesium metal have included molten baths containing MgCI2-LiCI mixtures with other salts such as KCI, BaCI2, NaCI, and CaCI2. Various types of trace metal such as vanadium, salts may be added to the mixed baths to enhance their electrolysis characteristics.

One of the more profound difficulties found in operting an electrolysis procedure to manufacture magnesium metal is the build up of cell "smut", which is primarily magnesium oxides, in the salt bath. This "smut" is not soluble in the eutectic molten baths and accumulates on electrodes, in flow paths, and generally throughout the equipment in contact with the molten salt bath. The presence of this "smut" is harmful to the electrolysis cell operation. It's presence is caused primarily by insufficiently dried magnesium chloride which is used as a cell feed during continued electrolysis.

Recently, new procedures have been developed to obtain high quality anhydrous magnesium chloride. These processes are described in U.S. Patent Nos. 3,983,244 and 3,966,888. These patents describe a process which successfully manufactures extremely high quality anhydrous MgCI2 from MgCI2 hydrate salts or concentrated MgCI2 aqueous solutions. These starting materials are admixed with ethylene glycol, exposed to temperatures sufficient to distill from these admixtures all water initially present leaving an an hydros ethylene glycol solution of MgCl2. This anhydrous ethylene glycol-MgCI2 solution is treated with anhydrous ammonia forming the insoluble MgCI2 . 6NH3-hexa ammoniate salt which precipitates and is then filtered from this glycol-MgCl2 6NH3 slurry.Subsequent unique washing steps, solvent recovery steps and a final roasting process which drives off ammonia (for recycle) and recovers high quality MgCI2 (anhydrous) completes the process.

One of the difficulties of the economic operation of the above process is the source of the MgCl2 hydrate salts or concentrated solutions. Brines, bitterns, and even sea water may be use to recover these hydrated MgCI2 salts or concentrated aqueous solutions.

The object of the present invention is to also use various types of naturally occurring mineral ores or mixed salts containing magnesium values and to simply and economically convert these mineral ores and mixed salts to anhydrous MgCl2.

We have discovered that we can easily achieve the beneficiation of certain ores and mixed salts containing magnesium values, and by such beneficiation open up many geographic locations to possible economic consideration as sites to manufacture MgCI2 (anhydrous) and possibly even magnesium metal.

We have particularly discovered a process which converts any common magnesium containing sulfate or chloride salt, double salt, or mixture thereof to anhydrous magnesium chloride of exceptionally high purity while simultaneously recovering either fertilizer grade potassium sulfate or recovering anhydrous and economically valuable potassium chloride. We have also successfully discovered a combined process which can use the an hydros potassium chloride recovered from the beneficiation of a carnallite double salt to improve the economics of recovering anhydrous magnesium chloride from a mixed salt containing magnesium sulfate and potassium sulfate.

We have discovered a method of beneficiating'a mixed salt mineral ore containing potassium and magnesium values in either the sulfate or the chloride form and in either their anhydrous or hydrated form which allows the recovery of anhydrous magnesium chloride and the simultaneous recovery of either commercially acceptable potassium chloride or commercially acceptable sulfate. This beneficiation of these mixed salt mineral ores allows the separation and isolation of several critical and economically valuable salts. These salts are anhydrous magnesium chloride, anhydrous potassium sulfate, and/or anhydrous potassium chloride.

We have simultaneously discovered that we may obtain an hydros magnesium chloride from either mixed chloride ores containing magnesium and potassium values, such as carnallite, or independently from mixed salts or magnesium sulfate and potassium sulfate which may also be found in various locations throughout the world. Examples of the mixed sulfate salts containing both magnesium and potassium values are the mineral ores named langbeinite, leonite, shoenite, and picromerite. The langbeinites are often given the formula K2SO4 2Mg S04 4H20. The hexahydrate salt is referred to as shoenite. The picromerite is another mineral name given to a magnesium-potassium sulfate ore which is commercially mined.

The potassium-magnesium containing mixed salts which have chloride ion concentrations are normally referred to as carnallites. These materials are most often found containing water of hydration, for example, MgCI2 KCI . 6H20.

The invention, therefore, is a combination of a method of beneficiating a mixed salt mineral ore containing potassium chloride and magnesium chloride and/or their hydrates which allows the recovery of anhydrous magnesium chloride and the simultaneous recovery of commercially acceptable potassium chloride, a method of beneficiating a mixed salt mineral ore containing potassium and magnesium sulfate and/or their hydrates which allows the recovery of anhydrous magnesium chloride and the simultaneous recovery of commercially acceptable potassium sulfate, and finally, the combination of these two methods of beneficiating magnesium ores of the type mentioned in such a manner that a commercial facility may use either a carnallite ore as a feed material, a mixed potassium/magnesium sulfate ore as a feed material, or may use a combination of these two mineral ores or types of ores as feed material to the process.

The simplest way of describing our invention is to outline the separate processes involved and then demonstrate their mutual combination. Toward that end, we initially will describe the process of beneficiating a carnallite type ore primarily containing MgCl2 . KCI and its various hydrate forms.

The method of beneficiating a mixed slat mineral ore containing potassium chloride and magnesium chloride and/or their hydrates allows the recovery of anhydrous magnesium chloride and the simultaneous recovery of commercially acceptable potassium chloride. This beneficiation of these carnallites allows the separation and isolation of two critical and economically valuable inorganic salts. These two salts are anhydrous magnesium chloride and potassium chloride.This method of beneficiation of these carnallite mineral ores which contain potassium chloride and magnesium chloride comprise the following steps: (a) Dissolving the carnallite mineral ores in the minimum amount of water required to obtain complete solubility, thereby obtaining a carnallite solution; (b) Filtering from the carnallite solution of (a) any residual precipitates which are not soluble in said solution, thereby obtaining a filtered solution; (c) Adding ethylene glycol to the filtered solution of (b) in sufficient quantities to solubilize all magnesium chloride present in said filtered solution, thereby obtaining an ethylene glycol-watercarnallite solution;; (d) Dehydrating the ethylene glycot-water-carnallite solution of step (c) by distilling water therefrom, thereby obtaining an anhydrous solution of magnesium chloride in ethylene glycol which may contain up to about 2.0% potassium chloride (by weight) and a precipitate of anhydrous potassium chloride, said precipitate then being removed and recovered from said solution of magnesium chloride in ethylene glycol;; (e) Adding anhydrous ammonia to the anhydrous solution of magnesium chloride in ethylene glycol, thereby forming a complex precipitate of MgCl2 . 6NH3 which may contain small quantities of KCI, said precipitate being filtered from the solution, washed with a low molecular weight solvent for ethylene glycol, said solvent having been saturated with anhydrous ammonia prior to washing said precipitate and recovering said washed precipitate of anhydrous MgCI2 . 6 NH3; (f) Heating the MgCI2 . 6NH3 of (e) to temperatures sufficient to drive off all ammonia, thereby recovering anhydrous magnesium chloride.

It is noted in step (e) that it is possible to remove trace quantities of potassium chloride from the MgCI2 . 6NH3/glycol cake by washing it with methanol saturated with ammonia in quantities sufficient to remove the potassium chloride. This is a surprising discovery since one would expect that the ammonia saturated methanol would not selectively extract the potassium chloride from the magnesium chloride ammoniate-glycol filter cake.

The sequence of steps outlined in the previous paragraphs allows for the production of anhydrous magnesium chloride of sufficient quality to be used as cell feed in an electrolysis cell recovering magnesium metal. In addition, it also allows the recovery of potassium chloride of sufficient quality to be used commercially.

Another operation that is preferred in this invention is the simultaneous dissolution and precipitation reactions that occur when water-ethylene glycol solutions are added to the original carnallite mineral ores. This mixture is then stirred and maintained at sufficient temperature to allow the solubilization of the mixed potassium and magnesium chloride making up the carnallite mineral ores. This solution, after treatment to remove any remaining suspended solids, is then dehydrated by distilling water therefrom, thereby obtaining an anhydrous solution of magnesium chloride in ethylene glycol which may contain up to about 2% potassium chloride (by weight). From this point on the procedures outlined above are followed to recover both the anhydrous magnesium chloride, potassium chloride as well as to recover and recycle the ethylene glycol, anhydrous ammonia, the low molecular weight solvent which is used to recover the glycol that is entrained in the magnesium chloride ammonia complex precipitate and to remove KCI from this complex precipitate.

It has been found that the use of a carnallite which contains water of hydration, for example-MgCl2 . KCI . 6H20, allows the use of ethylene glycol without the addition of more water to solubilize the carnallite material containing water of hydration. As an example of such a procedure, we present the possibility of adding sufficient hydrated carnallite as described above to ethylene glycol, such that a solution of magnesium chloride in the ethylene glycol after dehydration and removal of precipitated KCI would be between 8-10 weight percent. This solution is then heated to temperatures sufficient to distill from this solution the water of hydration contained in the original carnallite. As this distillation proceeds, the potassium chloride precipitates from the solution and may be recovered as described above.When the solution is totally anhydrous, the potassium chloride is removed by techniques described or anticipated above, and the magnesium chloride-ethylene glycol solution which may contain up to 2.0 weight percent potassium chloride is treated with anhydrous ammonia to form the magnesium chloride/ammonia complex precipitate and recovery steps are followed as described above.

Subsequent to the recovery steps mentioned, anhydrous anhydrous magnesium chloride is recovered, ethylene glycol is recovered and recycled, anhydrous ammonia is recovered and recycled, and the low molecular weight solvent for ethylene glycol is also recovered and recycled.

EXAMPLES 50 grams of carnallite (MgCl2KCI . 6H2O) was added to 250 grams of ethylene glycol. This solution was heated to the point at which water began to distill from the solution. This distillation was continued until all of the water that had been contained in this precipitate was removed, leaving behind an anhydrous solution which contained magnesium chloride, potassium chloride and ethylene glycol. In this solution was suspended anhydrous potassium chloride. This KCI was removed by filtration and the remaining solution was then cooled to room temperature, and sufficient anhydrous ammonia was added to precipitate from this solution all of the magnesium chloride values obtained therein.After the precipitation of the magnesium chloride/ammonia complex was complete, the complex precipitate was filtered from the solution and washed with methanol saturated with ammonia. This washing removed all of the entrained ethylene glycol contained in the magnesium chloride ammonia complex precipitate. The precipitate cake also contains some potassium chloride. However, this potassium chloride may also be removed by washing with additional methanol saturated with ammonia. The potassium chloride recovered in the methanol wash as a solution in methanol may be recovered from said solution by distillation procedures.

Table I presents the results of treating the original carnallite-ethylene glycol mixture mentioned above as outlined.

TABLE I Complex Ethylene Glycol Filter Cake Filtrate Mg 8.75% Mg 0.05% K 0.86% K 1.04% Cl 27.26% Cl 2.22% NH3 56.39% After MeOH (sat. NH3) Wash Complex Filtrate Filtrate Cake Wash Liquor Mg 11.27% Mg None Detected K 0.43% K 0.09% CI 33.82% Cl 0.13% NH3 (remainder) *Additional washing can rid the complex filter cake completely of KCI.

The processes developed for the beneficiation of the magnesium/potassium sulfate ores are previously described as recoveing economically valuable salts. ?These two salts are anhydrous magnesium chloride and potassium sulfate. This method of the beneficiation of these mixed salts containing potassium and magnesium sulfates comprise the following steps:: (a) Dissolving the mixed double salt containing magnesium and potassium sulfate in water at a temperature between 50"C and 90"C and then filtering the insoluble residue from the solution; (b) Adding to and dissolving into the filtered solution of step (a) a molar equivalent to potassium chloride, the molar equivalent calculated on the basis of the solubilized magnesium cation requirement for chloride ion, thereby forming a final solution; (c) Heating the final solution of step (b) to a temperature within the range of 50"C and 90"C for a period of time sufficient to allow chemical equilibrium to be established, thereby forming an equilibrated solution;; (d) Adding sufficient ethylene glycol to the equilibrated solution af step (c) to fully dissolve all magnesium chloride calculated to be present in that solution, then removing from the ethylene glycol-water solution the potassium sulfate which precipitated on the addition of said ethylene glycol; (e) Distilling water from the solution of step (d) thereby forming an anhydrous magnesium chloride solution in ethylene glycol and an anhydrous precipitate of potassium sulfate, then removing said K2SO4 precipitate from said solution; (f) Combining the potassium sulfate precipitates of steps (d) and (e) and washing said combined precipitates with sufficient water (maintained below 7Q"C) to remove entrained ethylene glycol, and recovering the washed potassium sulfate;; (g) Treating the anhydrous magnesium chloride solution in ethylene glycol formed in step (e) with anhydrous ammonia to form a magnesium chloride ammonia complex which precipitates from the ethylene glycol solution; (h) Removing the complex precipitate from the ethylene glycol and washing it with a low boiling solvent for ethylene glycol to remove any ethylene glycol entrained in the precipitate; (i) Heating the magnesium chloride ammonia complex to drive off ammonia leaving as a finished product completely anhydrous magnesium chloride.

The sequence of steps outlined in the previous paragraphs also allows for the production of anhydrous magnesium chloride of sufficient quality to be used as cell feed in an electrolysis cell recovering magnesium metal, In addition it allows for the recovery of potassium sulfate of sufficient quality to be used in commercial grade fertilizers.

Another operation that is preferred in this invention is the simultaneous dissolution and exchange reactions that occur when the mixed magnesium and potassium sulfates mineral ores previously mentioned are added to a mixture of water and glycol. This mixture is then stirred and maintained at a temperature between 50"C and 90"C for a period of time sufficient to dissolve the mixed double salt of magnesium and potassium sulfates.

To this mixture, after removal of any insoluble residues, either by filtration, centrifigation, or any other technique commonly used to separate solids from liquid solutions, is added sufficient potassium chloride to provide enough chloride ion to provide a molar equivalent of chloride ion for the solubilized magnesium cation present in this mixed solution. The potassium chloride may be commercially obtained or may be obtained from the previously outlined process for the beneficiation of carnallite ores, if the two processes are operated simultaneously. The rate of the dissolution of the added potassium chloride is enhanced by increasing the temperature to at least 50"C. A period of time sufficient to allow chemical equilibration has been found to be at least 1 5 minutes at theses temperatures.

After chemical equilibration has been established in this solution mixture, any residual precipitates are removed by common solid-liquid separation procedures. These precipitates contain primarily potassium sulfate. At this point the mixture is dehydrated by a distillation process such that the final solution derived following this distillation process is a mixture of an anhydrous potassium sulfate solid precipitate in a solution of an hydros MgCi2 in ethylene glycol.

Again the an hydros potassium sulffate is removed from this mixture, washed with cold water to recover ethylene glycol, and isolated for sale as a fertilizer. The remaining anhydrous magnesium chloride in ethylene glycol is treated as above, that is, by addition of anhydrous ammonia, separation of the magnesium chloride-ammonia complex from the ethylene glycol, washing the anhydrous magnesium chloride complex precipitate with a low boiling solvent for ethylene- glycol to remove the ethylene glycol entrained in this precipitate, and finally heating the MgCI2 ammonia complex to drive off and recover the ammonia and leave as a finished product a completely anhydrous magnesium chloride.

The Mixed Salts The mixed salts of magnesium sulfate and potassium sulfate are found in various locations throughout the world. An example of these salts are the mineral ores called Langbeinite, Leonite, Schoenite, and Picromerite. The Langbeinites are often given the formula K2S04 . 2MgSO4.

Leonite on the other hand is a tetrahydrate having the formula K2S04 . MgSO4 4H20. The hexahydrate salt, K2SO4 MgSO4 6H20, is referred as Schoenite. The Picromerite is another mineral name given to a magnesium potassium sulfate ore that is commercially mined.

In the practice of this invention, the source of the mixed salts is not particularly important. It is, however, important that the minerals used as raw materials be somewhat free of impurities.

However, it has been found that by following the procedures outlined previously, even these impurities can be precipitated and isolated from the products of these reactions. The impurities normally would be isolated either by initial filtration of a water solution, by the second filtrations or solids isolations following the first addition of glycol to the water solution, or finally isolated following- the total dehydration step leading to the magnesium chloride glycol solutions mentioned above.

The reactions mentioned above are limited to those solutions that contain water. A demonstration of this is found in an attempt to accomplish the above reactions and the above beneficiation of the mixed salts containing potassium and magnesium sulfates by the procedures outlined above in totally an hydros and non-aqueous solvent systems. Those solvent systems checked included methanol, acetone, ethylene glycol, the diethylether of tetraethylene glycol, and tetraethylene glycol. Without the presence of water, no metathetical exchange reactions occurred that would be of more than nominal interest. The organic solvent systems mentioned above were checked both as is and in the presence of aqueous mixtures. There was no reaction between the potassium chloride and the minerals containing potassium and magnesium sulfate in the organic solvents as is.Water had to be added for the metathetical exchange reactions to occur. However, those reactions made using the solvent as an aqueous solution provided no additional benefit to the metathetical reactions or their rates that occurred when using only an equivalent amount of water. The presence of the organic compounds were not found to enhance the metathetical exchange reaction rates.

Various additives were used, and none used seemed to improve the yield or the final brine concentration. The addition of small amounts of polyacrylic acid, ammonium chloride, magnesium chloride, sodium chloride, and calcium chloride had no effect on the extent of the metathetical reaction or the rate of the metathetical reactions. Trace amounts of inorganic acids, such as sulfuric acid and hydrochloric acid, seemed to depress the extent of the reaction as well as the rate of the metathetical exchange reactions.

From the work that we have completed, it would appear that the potassium sulfate formed by the metathetical reactions outlined above or initially present in the mixed salts must be removed from the solution as the reaction proceeds to allow the maximum degree of this metathetical reaction to occur.

EXAMPLES A typical example of the beneficiation of the mixed double salt containing magnesium sulfate and potassium sulfate is outlined below.

29.5 grams of a double salt which analyzed as containing 10.7% magnesium and 18.2% potassium, the remainder being sulfate and trace quantities of other salts, was added to 60 grams of water and heated to 80"C. This mixture was stirred and allowed to dissolve (approximately 5 min.). To this mixture was added 14.9 grams of potassium chloride followed by additional stirring and heating. A reaction time and equilibration time of from 3 to 10 minutes was allowed. This mixture was then filtered to accomplish a removal of insoluble salts.

To the filtrate was added 90 grams of ethylene glycol. This mixture was then heated until the water began to distill from these mixed solutions. As the water is removed, an hydros potassium sulfate precipitates from the solution remaining. The distillation is complete when no further water can be removed from the solution mixture remaining. At that time the entire amount of potassium sulfate initially present has precipitated and the remaining solution is composed of anhydrous magnesium chloride in ethylene glycol. This anhydrous solution of magnesium chloride in glycol is recovered through a filtration or any solids-liquid separation technique of choice while simultaneously recovering the glycol wetted potassium sulfate precipitate.The potassium sulfate precipitate is given a cold water wash (temperatures are maintained below 70"C) and analyzes at a sufficient quality to be sold as a potassium sulfate fertilizer. The MgCI2 solution in ethylene glycol is exposed to anhydrous ammonium chloride which precipitates the MgCI2 as a complex whose formula is thought to be MgCI2 . 6NH3. This MgCI2 ammonia precipitate is removed from the glycol solution, washed with a solvent for ethylene glycol that is a low boiling solvent, and then heated to temperatures that are sufficient to drive off the complexed ammonia. These reactions to isolate the anhydrous MgCI2 from the MgCI2 ammonia comple are outlined in U.S. patents 3,983,244 and U.S. 3,966,888.

Additional work was done which allowed the definition of reactions which would lead to a higher concentration of MgCI2 in both the initial brines as well as the ethylene glycol-MgCI2 brines. The summary of the reactions are given in Table II. This table will outline the amount of double salt reaction with KCI, the amount of water and ethylene glycol used in the reaction, the temperatures of the reaction, the extent of the metathetical exchange, and the effects of any added salts such as magnesium chloride, sodium chloride and calcium chloride.

TABLE II MgSO4 . K2SO4 Double Salt KCl MgCl2 . 6H2O NaCl CaCl2 . 2H2O Water Ethylene Glycol Grams Grams Grams Grams Grams Grams Grams Remarks 25 16 100 5.7% MgCl2 solution 25 16 100 Very little reaction; Mg = 0.7% 50 32 100 500 50% Mg reacted 25 16 250 Mg =.28% 25 16 70 250 70% Mg reacted 25 9 23 250 100% reaction; 8.6% MgCl2 solution 25 9 23 125 100% reaction; 9.9% MgCl2 solution 25 18 5 150 100% reaction; 6.8% MgCl2 solution 25 18 23 150 100% reaction; 8.6% MgCl2 solution 25 18 5 50 150 No reaction 25 18 23 50 150 No reaction 25 18 23 190 100% reaction; 10% MgCl2 solution 25 12 200 100% reaction; 6% MgCl2 solution 25 60 50% reaction; 9% MgCl2 29 15 12 200 100% reaction; 4.9% MgCl2 29 30 200 100% reaction; 4.1% MgCl2 25 12 200 100% reaction; 5% MgCl2 29 15 8 100 100% reaction; 5.5% MgCl2 29 18 1 50 150 50% reaction 29 18 6 50 150 50% reaction 29 18 23 190 20 at 80 C-90% reaction 29 18 23 190 40 at 80 C-100% reaction 29 18 23 190 60 at 80 C-100% reaction 29 18 7 190 20 at 80 C-80% reaction 29 18 7 190 40 at 80 C-100% reaction 29 18 7 190 60 at 80 C-100% reaction 29 18 5 190 20 at 80 C-100% reaction 29 18 5 190 40 at 80 C-100% reaction 29 18 5 190 60 at 80 C-100% reaction 29 15 190 10 at 80 C-85% reaction 29 15 190 15 at 80 C-100% reaction 29 15 190 20 at 80 C-100% reaction 29 15 190 40 at 80 C-100% reaction 29 18 50 200 No reaction 29 13 190 20 at 80 C-90% reaction 29 13 190 40 at 80 C-100% reaction 29 13 190 60 at 80 C-100% reaction 29 15 13 190 20 at 80 C-100% reaction Examination of Table II and observations made when attempting to work with more concentrated solutions of the double salt containing MgSO4 and K2SO4 allow us to conceive of a process that would convert only a portion of the double salt magnesium values to anhydrous MgCI2 in glycol. The portion of unreacted double salt, unreacted potassium chloride, and the potassium sulfate product derived from the metathetical exchange reaction that would be present in the precipitates in the previously described process steps could be recycled back to earlier process steps and still derive the benefits of the invention.

The combination of the above techniques allows the recovery of an hydros magnesium chloride by simultaneously treating carnallite ores, as previously described, and mixed sulfate ores containing magnesium and potassium values. Fig. I outlines in block diagram form a potential process for accomplishing this beneficiation and recovery of high purity, high quality, anhydrous MgCI2 suitable for use as electrolysis cell feed in the recovery of magnesium metal.

Either anhydrous KCI or anhydrous K2SO4 or a combination of the two may be recovered by this process, depending on the relative amounts of either type of mixed ores are being processed.

The blocks in the process outlined in Fig. I are meant to represent each of the steps previously described in the separate detailed outline of the individual processes. The benefits of the combined process are obvious; First, only a single processing scheme is necessary to isolate MgCI2 (anhydrous) from the MgCI2 . 6NH3/glycol slurry formed in both processes. This eliminates equipment duplication and has obvious economic advantages; secondly, the KCI byproduct obtained from the carnallite beneficiatior may be used advantageously as a raw material in the initial metathetical exchange reactions required for the beneficiation of the mixed Mg/K sulfate salts; Lastly, the combination of the two processes allows technical, processing, and economic variability which may be used to advantage depending on pricing and availability of all raw materials.

Although Fig. I describes, in diagram form a combination, it is not our intention to be limited by its particular schematic design. Many flexabilities may be anticipated from the diagram as well as the previous descriptions.

Claims

1. A process to beneficiate carnallite mineral ores for the purpose of recovering anhydrous MgCI2 and KCI said process comprising the following steps: (a) Dissolving the carnallite mineral ores in the minimum amount of water required to obtain complete solubility, thereby obtaining a carnallite solution; (b) Filtering from the carnallite solution of (a) any residual precipitates which are not soluble in said solution, thereby obtaining a filtered solution; (c) Adding ethylene glycol to the filtered solution of (b) in sufficient quantity to solubilize all MgCI2 present in said filtered solution, thereby obtaining an ethylene glycol-water-carnallite solution;; (d) Dehydrating the ethylene glycol-water-carnallite solution of step (c) by distilling water therefrom, thereby obtaining an anhydrous solution of MgCI2 in ethylene glycol which may contain up to about 2.0% KCI (be weight) and a precipitate of anhydrous potassium chloride, said precipitate then being removed and recovered from said solution of MgCI2 in ethylene glycol, thereby obtaining an anhydrous solution of MgCI2 in ethylene glycol; (e) Adding to the anhydrous solution of MgCI2 in ethylene glycol anhydrous ammonia thereby forming a precipitate of MgCI2 . 6NH3, said precipitate being filtered from solution, washed with a low molecular weight solvent for ethylene glycol, said solvent having been saturated with anhydrous ammonia prior to washing said precipitate, and recovering said washed precipitate of anhydrous MgCI2 . 6NH3;; (f) Heating the MgCI2 . 6NH3 of (e) to temperatures sufficient to drive off all ammonia, thereby recovering an hydros MgCl2.

2. A method of removing trace quantities of potassium chloride from glycol wet filter cakes of MgCI2 6NH3 which comprises washing said cakes with methanol saturated with ammonia in a quantity sufficient to remove the potassium chloride and the glycol from said cake.

3. A method for the beneficiation of mixed salts containing potassium and magnesium sulfates which allows the recovery of anhydrous MgCI2 and the recovery of potassium sulfate, said method comprising the steps: (a) Dissolving a mixed double salt/magnesium and potassium sulfates in water at a temperature between 50"C and 90"C and then filtering the residue from the solution; (b) Adding to and dissolving into the filtered solution of (a), a molar equivalent of potassium chloride, the molar equivalent calculated on the solubilized magnesium cation requirement for chloride ion, a solution; (c) Heating the solution produced in step (b) within the range of 50"C-90"C for a period of time to allow equilibrium to be established, thereby forming an eqilibriated solution;; (d) Adding sufficient ethylene glycol to the equilibriated solution of (c) to fully dissolve all MgCI2 calculated to be present, then removing from solution the K2504 which precipitated on the addition of said ethylene glycol; (e) Distilling water from the solution of step (d) thereby forming an anhydrous MgCI2 solution in ethylene glycol and a precipitate of K2SO4, then removing said precipitate from said solution; (f) Combining the K2SO4 precipitate of steps (d) and (e) and washing said precipitates with sufficient water maintained below 70"C to remove entrained ethylene glycol, and recovering the washed K2SO4; (g) Treating the anhydrous MgCI2 solution in ethylene glycol formed in step (e) with anhydrous ammonia to form a MgCI2-ammonia complex which precipitates from the ethylene glycol solution;; (h) Removing the complex precipitate from the ethylene glycol and washing it with a low boiling solvent for ethylene glycol to remove any (EG) entrained in the precipitate; (i) Heating the magnesium chloride ammonia complex to drive off ammonia leaving as a finished product completely anhydrous magnesium chloride.

4. The method of claim 3, comprising the use of a Langbeinite material ore as the source of the mixed salts containing potassium and magnesium sulfates.

5. The method of claim 3, comprising the use of a Leonite mineral ore as the source of the mixed salts containing potassium and magnesium sulfates.

6. The method of claim 3, comprising the use of Schoenite mineral ore as the source of the mixed salts containing potassium and magnesium sulfates.

7. The method of claim 3, comprising the use of Picromerite mineral ore as the source of the mixed salts containing potassium and magnesium sulfates.

8. A process of recovering anhydrous MgC12 and recovering either anhydrous KgCI2 or anhydrous K2SO4, or both, said process consisting essentially of following, in a simultaneous manner, the method and process described in claim 1 and in claim 3.

9. The process of claim 8, wherein the KCI by product obtained by beneficiating carnallite ores is used as a raw material in the process of recovering anhydrous MgCI2 from mixed salts containing magnesium and potassium sulfates.

10. A process to beneficiate carnallite mineral ores for the purpose of recovering anhydrous MgCI2 and KCI substantially as herein described with reference to the examples.

11. A method for the beneficiation of mixed salts containing potassium and magnesium sulfates which allows the recovery of anhydrous MgCl2 and the recovery of potassium sulfate, substantially as herein described with reference to the examples.