NL8001653A - METHOD FOR PREPARING MAGNESIUM CHLORIDE. - Google Patents

Description

S 3609-43 P&C

Process for the preparation of magnesium chloride.

The invention relates to the preparation of magnesium chloride.

To prepare metallic magnesium, anhydrous magnesium chloride is normally electrolysed in a molten eutectic salt mixture. The metallic magnesium is separated from the bath and the electrolytic cell by flotation in molten baths containing mainly MgCl2, KCl and NaCl, as well as CaCl2. Other "mixed" eutectic salt baths that have been used to recover metallic magnesium include molten baths containing MgCl 2 -LiCl mixtures with other salts, such as KCl, BaCl 2, NaCl and CaCl 2. Different types of trace metals, such as vanadium, can be added to the mixed baths in the form of salts to improve the electrolysis properties.

One of the major difficulties in performing an electrolysis process for preparing metallic magnesium is the accumulation of cell contamination ("smut"), which is mainly formed by magnesium oxides, in the salt bath. This cellular contamination 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 impurity is detrimental to the operation of the electrolysis cell. Its presence is mainly caused by insufficiently dried magnesium chloride, which is used as a feed to the cell during continued electrolysis.

Recently, new methods have been developed for obtaining high quality anhydrous magnesium chloride. These methods are described in U.S. Pat. Nos. 3,983,244 and 3,966,888. These patents describe a process for successfully obtaining extremely high quality anhydrous MgCl 2 from MgCl 2 hydrates or concentrated aqueous MgCl 2 solutions. These starting materials are mixed with ethylene glycol, and exposed to temperatures sufficient to distill all the water originally present from these mixtures, leaving an anhydrous solution of MgCl 2 in ethylene glycol. This anhydrous ethylene glycol MgCl2 solution is treated with anhydrous ammonia to form the insoluble MgCl2 (NE) salt (hexammonia salt) that precipitates and then filtered from this glycol MgCl2 SNH2 slurry. Subsequent special washes, solvent recovery steps and a final roasting step, which expels ammonia (for recirculation) and isolates high-quality anhydrous MgCl2, complete the process.

800 1 6 53

V

- 2 -

One of the difficulties associated with an economical implementation of the above-discussed process is the source of the MgCl 2 hydrates or concentrated MgCl 2 solutions. Saline solutions, mother liquor and even seawater can be used to obtain these hydrated MgCl2 salts or concentrated aqueous solutions.

According to the invention, different types of naturally occurring mineral ores or mixed salts containing magnesium values are used and these mineral ores or mixed salts are converted into anhydrous MgCl 2 in a simple and economical manner.

It has now been found that certain ores and mixed salts containing magnesium values can be easily treated to prepare MgCl2 (anhydrous) and optionally even metallic magnesium, through which treatment many geographical areas can become economically important. In particular, a process has been found according to which any conventional magnesium-containing sulfate or chloride salt, double salt or mixture thereof is converted into anhydrous magnesium chloride of exceptionally high purity, while simultaneously isolating fertilizer quality potassium sulfate or anhydrous and economically valuable potassium chloride . Also, a combined process has been found wherein the anhydrous potassium chloride obtained by treating a carnallite (double salt) can be successfully used to improve the economy of recovering anhydrous magnesium chloride from a mixed salt containing magnesium sulfate and potassium sulfate contains.

A process has been found for treating a mineral ore-containing mixed salt containing potassium and magnesium values in the sulfate or chloride form, in anhydrous or hydrated form, which process makes it possible to obtain anhydrous magnesium chloride and at the same time commercially acceptable potassium chloride or commercially acceptable sulfate. This treatment of these mixed salts makes it possible to separate and isolate various critical and economically valuable salts. These salts are anhydrous magnesium chloride, anhydrous potassium sulfate and / or anhydrous potassium chloride.

It has also been found that anhydrous magnesium chloride can be obtained from mixed chloride ores containing magnesium and potassium values, such as carnallite, or from the mixed salts magnesium sulfate and potassium sulfate, which are also found in various locations around the world. Examples of the mixed sulphate salts containing both magnesium and potassium values are the mineral ores of langbeinite, leonite, schoenite and picromerite. The Langbeinites often use the formula 80 0 1 6 53 - 3 -

* * V

K2S04.2MgS04.4H20 assigned. The hexahydrate salt is called Schoenite. Picromerite is the name of another magnesium potassium sulfate ore that is commercially mined.

The potassium-magnesium-containing mixed salts with chloride ions are normally called carnallites. These materials very often contain hydrate water, for example MgCl2.KC1.6H20.

The invention therefore provides a method of treating a mixed salt (mineral ore) containing potassium chloride and magnesium chloride and / or their hydrates, which method allows the recovery of anhydrous magnesium chloride and the simultaneous recovery of commercially acceptable potassium chloride; a method of treating a mixed salt (mineral ore) containing potassium and magnesium sulfate and / or their hydrates, which permits the recovery of anhydrous magnesium chloride and the simultaneous recovery of commercially acceptable potassium sulfate; and finally a combination of these two methods of treating magnesium-containing ores of said types; According to the invention, a commercial plant may use as a starting material a carnallite ore, a mixed potassium / magnesium sulfate ore or a combination of these two mineral ores or types of ore.

The individual methods are described below, after which the combination of these methods is discussed. First, the method of treating a carnallite type ore containing mainly MgCl2.KCl and the various hydrate forms is described.

The treatment of a mixed salt (mineral ore) containing potassium chloride and magnesium chloride and / or their hydrates makes it possible to obtain anhydrous magnesium chloride and simultaneously commercially acceptable potassium chloride. This treatment of the carnallites enables 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 treating mineral carnallite ores containing potassium chloride and magnesium chloride includes the following steps; (a) The mineral carnallite ore is dissolved in the minimum amount of water required to obtain complete solubility, to obtain a carnallite solution; (B) the carnallite solution obtained in step (a) is filtered to remove any residual precipitates that are not soluble in the solution, to obtain a filtered solution; (c) ethylene glycol is added to the filtered solution obtained in step (b) in an amount sufficient to dissolve all the magnesium 80 0 1 fi 53-4 chloride present in the filtered solution to obtain an ethylene glycol, water and carnallite-containing solution; (d) the ethylene glycol-water-carnallite solution of step (c) is freed from water by distilling water therefrom, to obtain an anhydrous solution of magnesium chloride in ethylene glycol, which can be up to about 2.0 wt% potassium chloride and a precipitate of anhydrous potassium chloride, which precipitate is then removed from the solution of magnesium chloride in ethylene glycol and isolated; (E) Anhydrous ammonia is added to the anhydrous solution of magnesium chloride in ethylene glycol to form a complex precipitate of the formula MgC 2 .NH 3, which may contain a small amount of KCl, which precipitate is filtered from the solution, washed with a solvent for ethylene glycol, which solvent has a low molecular weight and is saturated with anhydrous ammonia before washing the precipitate, and the washed precipitate of anhydrous MgC1. (f) the MgClg.SNH2 obtained in step (e) is heated to a temperature sufficient to expel all the ammonia to obtain anhydrous magnesium chloride.

It is noted that in step (e) it is possible to remove trace amounts of potassium chloride from the MgC 2 OH NH / glycol cake by washing this cake with methanol saturated with ammonia in an amount sufficient to remove the potassium chloride. This is a surprising discovery since it would be expected that the ammonia-saturated methanol would not selectively extract the potassium chloride from the magnesium chloride-ammonia complex and glycol filter cake.

The above steps allow the preparation of anhydrous magnesium chloride of sufficient quality to be used as starting material in an electrolysis cell for the preparation of metallic magnesium. Furthermore, this method also allows the recovery of potassium chloride of sufficient quality to be used commercially.

In a preferred embodiment of the invention, dissolution and precipitation are allowed to occur simultaneously by adding water ethylene glycol solutions to the original carallite ore. The resulting mixture is stirred and kept at a sufficient temperature to allow the dissolution of the mixed potassium magnesium chloride, which forms the carnallite ore. Then, after treatment to remove any remaining suspended solid, this solution is freed from water by distilling water therefrom, 80 0 1 6 53 * 1 - 5 - to obtain an anhydrous solution of magnesium chloride in ethylene glycol, which is up to about 2 wt. .% potassium chloride. From this point, the above-described methods are followed to recover anhydrous magnesium chloride and potassium chloride as well as ethylene glycol, anhydrous ammonia and the low molecular weight solvent used to recover the glycol retained in the precipitated magnesium chloride. ammonia complex and for removing KC1 from this complex precipitate, to be recovered and recycled.

10 "It has been found that the use of a carnallite containing hydrate water, for example MgCl2.KCl.6H2O, allows the use of ethylene glycol without adding more water to dissolve the hydrate water containing carallite material. For example, it is possible to of the above hydrated carnallite to ethylene glycol so that after removal of water and precipitated KCl a solution of 8-10 wt.% magnesium chloride in ethylene glycol is obtained.

This solution is then heated to a temperature sufficient to distill the hydrate water present in the original carnallite from this solution. As distillation proceeds, the potassium chloride precipitates from the solution, which precipitate can be isolated as described above. When the solution is completely anhydrous, the potassium chloride is removed as described above; the magnesium chloride ethylene glycol solution, which may contain up to 2.0 wt% potassium chloride, is treated with anhydrous ammonia to form a precipitate of the above magnesium chloride / ammonia complex; the following steps are the same described above. After these steps, anhydrous magnesium chloride is isolated, ethylene glycol is recovered and recycled, anhydrous ammonia is recovered and recycled, and the low molecular weight -30 solvent for ethylene glycol is also recovered and recycled.

EXAMPLE I

50 g of carnallite (MgC ^ KCl.S ^ O) was added to 250 g of ethylene glycol. This solution was heated to the point where water began to distill from the solution. This distillation was continued until all the water present in the carnallite was removed leaving an anhydrous solution containing magnesium chloride, potassium chloride and ethylene glycol. Anhydrous potassium chloride was suspended in this solution.

This KCl was removed by filtration; the remaining solution was then cooled to room temperature, and sufficient anhydrous 80 0 1 6 53-6 ammonia was added to precipitate from this solution all the magnesium chloride contained therein. After the precipitation of the magnesium chloride / ammonia complex was completed, the complex precipitate was removed from the solution by filtration and washed with methanol saturated with 5 ammonia. All of the ethylene glycol present in the precipitated magnesium chloride-ammonia complex was removed by this washing treatment. The precipitate cake also contained some potassium chloride. However, this potassium chloride can also be removed by washing with a further amount of methanol saturated with ammonia. The potassium chloride obtained on washing with methanol as a solution in methanol can be isolated from the solution by distillation.

Table A gives the results of the above-described treatment of the above original carnallite-ethylene glycol mixture.

TABLE A

15 Filter cake of complex Ethylene glycol lltrate

Mg 8.75% Mg 0.05% K 0.86% K 1.04%

Cl 27.26% Cl 2.22% NH3 56.39% 20 After washing with CHoOH (saturated with NH.)

1) J J

Filter cake of complex filtrate washing liquid

Mg 11.27% Mg Not shown K 0.43% K 0.09%

Cl 33.82% Cl 0.13% 25 NH3 (residual) 1) By further washing, the filter cake of the complex can be completely freed from KCl.

As mentioned above, in the method of treating magnesium / potassium sulfate ores, economically valuable salts are isolated. These two salts are anhydrous magnesium chloride and potassium sulfate. According to this method of treating the mixed salts containing potassium and magnesium sulfate, the following steps are performed: (a) The mixed salt (double salt) containing magnesium and potassium sulfate is dissolved in water at a temperature of 50®-90®C and then the insoluble residue is filtered from the solution; (b) a molar equivalent of potassium chloride is added to the filtered solution obtained in step (a) and dissolved therein, the molar equivalent calculated on the basis of the chloride ions required for the dissolved magnesium cations, to form a final solution; g Q 0 1 6 53 * * - 7 - (c) the final solution obtained in step (b) is heated to a temperature of 50® - 90®C for a period sufficient to allow a chemical equilibrium to be established, under formation of an equilibrated solution; 5 (d) to the equilibrated solution of step (c), enough ethylene glycol is added to dissolve the entire calculated amount of magnesium chloride contained in the solution, and then the potassium sulfate which is removed from the ethylene glycol water solution. precipitated upon addition of the ethylene glycol; (E) distilling water from the solution obtained in step (d) to form an anhydrous magnesium chloride solution in ethylene glycol and an anhydrous precipitate of potassium sulfate, then removing the K2 SO4 precipitate from the solution; (f) the potassium sulfate precipitates from steps (d) and (e) are combined and the combined precipitates are washed with sufficient water (kept at a temperature below 70 ° C) to remove ethylene glycol contained in the precipitate, and isolates the washed potassium sulfate; (g) the anhydrous solution of magnesium chloride in ethylene glycol obtained in step (e) is treated with anhydrous ammonia to form a magnesium chloride-ammonia complex which precipitates from the solution in ethylene glycol; (h) removing the precipitated complex from the ethylene glycol and washing the precipitate with a low boiling solvent for ethylene glycol to remove any ethylene glycol present in the precipitate; (I) The magnesium chloride-ammonia complex is heated to expel the ammonia, leaving as an end product completely anhydrous magnesium chloride.

The above series of steps also allows the preparation of anhydrous magnesium chloride of sufficient quality to be used as a starting material in an electrolytic cell for the preparation of metallic magnesium. This method also allows the obtainment of potassium sulfate of sufficient quality to be used in commercial grade fertilizers.

According to the invention, it is preferable to allow the dissolution and the exchange reaction to take place simultaneously by adding the above-mentioned magnesium and potassium sulfate (mineral ore) to a mixture of water and glycol. This mixture is then stirred and kept at a temperature between 50®C and 90®C for a period sufficient to dissolve the mixed salt (magnesium and potassium sulfate).

80 0 1 6 53 - 8 -

After removal of any insoluble residue, by filtration, centrifugation, or other conventional method of separating solid from liquids, sufficient potassium chloride is added to this mixture to provide sufficient chloride ions, namely a molar equivalent of chloride ions for the dissolved magnesium cations present in the solution. The potassium chloride can be obtained commercially or can be obtained according to the carnallite ores treatment method discussed above if the two methods are performed simultaneously. Dissolving the added potassium chloride 10 is improved by raising the temperature to at least 50 ° C. At these temperatures, it has been found that the time required to establish a chemical equilibrium is at least 15 minutes.

After a chemical equilibrium has established itself in the solution, any remaining precipitates are removed by conventional solid-liquid separation methods. These deposits mainly contain potassium sulfate. At this point, the mixture is freed from water by distillation, so that the solution obtained after this distillation is a mixture of precipitated anhydrous potassium sulfate and a solution of anhydrous MgCl 2 in ethylene glycol.

The anhydrous potassium sulfate is removed from this mixture, washed with cold water to recover ethylene glycol, and isolated for marketing as fertilizer. The residual anhydrous magnesium chloride in ethylene glycol is treated as described above, ie by adding anhydrous ammonia, separating the magnesium chloride-ammonia complex from the ethylene glycol, washing the precipitated anhydrous magnesium chloride complex with a low boiling solvent for ethylene glycol to remove the ethylene glycol present in this precipitate, and finally heating the MgCl 2 ammonia complex to drive out and recover the ammonia, leaving a completely anhydrous magnesium chloride as the final product.

The mixed salts

The mixed salts of magnesium sulfate and potassium sulfate are found in various places around the world. Examples of these salts are the mineral ores of langbeinite, leonite, schoenite and picromerite. Langbeinites are often assigned the formula K2S0 ^ .2MgSO ^. Leonite is a tetrahydrate with the formula K2 SO ^ .MgSO ^ .4H20. The hexahydrate salt, K2SO ^. MgSO ^ .6 ^ 0, is called Schoenite. Picromerite is the name of another magnesium potassium sulfate ore that is commercially mined 80 0 1 6 53-9.

According to the invention, the source of the mixed salts is not of particular importance. However, it is important that the minerals used as starting materials are somewhat free from contaminants. However, it has been found that by using the methods discussed above, even these impurities can be precipitated and isolated from the products of these reactions. The impurities are normally isolated by initial filtration of an aqueous solution, by second filtration or solid isolation after the first addition of glycol to the aqueous solution, and by isolation after the total dewatering step leading to the above magnesium chloride glycol solutions.

The above reactions are limited to the solutions containing water. This was evidenced by an attempt to carry out the above reactions for treating the mixed salts (potassium and magnesium sulfate) in completely anhydrous and non-aqueous solvent systems by the methods described above. The solvents tested included methanol, acetone, ethylene glycol, the diethyl ether of tetraethylene glycol and tetraethylene glycol. Without the presence of water, no exchange reactions of more than nominal importance took place. The above-mentioned organic solvents were tested as such and in the presence of aqueous mixtures. No reaction took place between the potassium chloride and the mineral materials containing potassium and magnesium sulfate in the organic solvents. Water had to be added in order for an exchange reaction to occur. The use of the solvent as an aqueous solution gave no additional advantage in terms of the reactions and rates thereof, over the use of only an equivalent amount of water. The presence of the organic compounds was found not to improve the exchange reaction rates.

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

It has been found that the potassium sulfate formed by the above reaction or initially present in the mixed salts must be removed from the solution as the reaction proceeds 800 1 6 53 -10- to allow maximum conversion take place.

EXAMPLE II

Below is a representative example of the treatment of a double salt containing magnesium sulfate and potassium sulfate.

29.5 g of a double salt, which, according to analysis, contained 10.7% magnesium and 18.2% potassium and the remainder sulfate and trace amounts of other salts, was added to 60 g water and heated to 80 ° C. This mixture was stirred and dissolved (about 5 minutes). 14.9 g of potassium chloride were added to the resulting mixture, followed by further stirring and heating. A reaction time and an equilibrium time of 3-10 minutes were used. The mixture was then filtered to remove insoluble salts. 90 g of ethylene glycol were added to the mixture. The mixture was then heated until water started to distill therefrom. During the removal of the water, anhydrous potassium sulfate precipitated from the remaining solution. Distillation is complete when no further water can be removed from the remaining solution. At this time, the entire amount of potassium sulfate initially present has precipitated and the remaining solution is anhydrous magnesium chloride in ethylene glycol.

This anhydrous solution of magnesium chloride in glycol is isolated by filtration or other solid-liquid separation method, simultaneously isolating the glycol-wetted potassium sulfate precipitate. The precipitated potassium sulfate was washed with cold water (the temperature was kept below 70 ° C); analysis shows that this precipitate was of sufficient quality to be marketed as fertilizer. The solution of MgCl2 in ethylene glycol was treated with anhydrous ammonia to precipitate the MgCl2 in the form of a complex believed to be the formula MgC2. This MgCl 2 ammonia precipitate was removed from the glycol, washed with a low boiling solvent for ethylene glycol, and then heated to a temperature sufficient to expel the ammonia present in the complex. These steps for isolating anhydrous MgCl2 from the MgCl2-ammonia complex are described in U.S. Pat. Nos. 3,983,244 and 3,966,888.

Furthermore, a study was conducted on reactions leading to a higher concentration of MgCl2 in both the initial saline and in the ethylene glycol MgCl2 solution. The reactions are summarized in Table B. This table lists the amount of double salt for the reaction with KCl, the amounts of water and ethylene glycol used, the reaction temperature 800 1 6 53 - 11 - the degree of the exchange reaction, and the effects of any added salts such as magnesium chloride, sodium chloride and calcium chloride.

80 0 1 6 53 - 12 - iji Ui Ui Ui tT> Ö> _ BB CCfiC g1 • HHHH Η HGO 'οι jj cn tn ω cn -hg cn + j tn cn cn tn cn h ooi -o - o ·· » o "· ov · 3 · * £ £, -tn 4j -uo \ <- t cn · —i spout — t tn« —j © o © cn · χ ui

ftg 0) oöö) GQ (GftG0i © © GHGO © G

0 0 N N Η o Ή O Η O H O G G H ft Η H G H

1 φ φ 4J | -UI -UI -PI Ή iH -PO + ft -ri + J

G CS UI Ui dP υι +) £ Ν-ΡεΝ +) ίΝ +) £ Ν + 1 · Ρ · Ι-> Ι +} O -P +> CN

φ H dP S SUHCUt-iCUHCUr-i + J-G OJCNCUI + J CD H

OIO G O COO NO NO NO NO Φ <D NH N CN φ CN N O

G iji H © rs S © S © g © gU N N S O Η H NH S & 1 • H a <Ü χ © - & Ö S OS Sa OS g g OfrOOSOOa λ; s; o a o a oo a & o © ^ CH> dPdPdPdPdPdPdPdP dP # S S # #

MUlldPlIdP G G dP dP

|> Φ o <oouocooio <d <do o # d? ewe 01 χ <U U O UlOOxOxOxOxCU Φ O O O O O -

O ΙΠ Na LO S f- η ffl rH tn rt vfl rt Ο Ο U Η H tHVO LDCTl * -d NP

r- \ o o> 1 t — i G * ioooo oo Φ Mo o tn tn tn tn φ © r-d UI CN CN T-f-r-i

H

s

+ J

H

Jj φ S O O OO LH o o o o o o o o yy (ö o o r ~ in cn m tn tn tn © o o o -

(Ö M * - <t-4 CN * - <* - <* “<T-ICN CN

J3 UI

(5

tG

approx

PQ

c o

Ed CN

M S

CN 10 • M CO CO CN Ο co CN © * -) Ή © vd τΗ

rH

o rö o

O i CN CN

(O M ^ ^ s o o

CN

tCJ S

νηφ © ro tn © cn cn rn

. M CN CN CN CN CN

CN U H

o u s s OM Öï © CO CO CO CO CO ΙΟ © τΗ tH * -f * -d t- (d-d

Nf + J O G W 0 CN N S

cd h cd tn tn o in co cn cn cn cn cncncn cn cn o

• O M CN CN cn CN CN CN CN CN CN CNCNCN CN CN CN

YOU

O Λ W G U Ό a ~

8 0 0 1 6 53 cn o cn o JQ

- 13 - hirriöi Öi &> ÖiDiO> ÖtOi ö rj rj Dl Dl Ol (3 (3 tjfcö Ü ö β ^ H -H -H (3 (3 I Ö 1 -5 I · Η I (3 i -H! -HI) -H 1 -Η I -rj

ö 4J CS Ü Ü CS + J +3 O + J O + J O + J O 4J O + J P ^ U + JU-PU-P

Oi NU N CS N O CD (DOCDONONOtUONONONONON

C g Ol g H g D> NN CO N CO 6 CO g 00 N CO g CO g CO g 00 g CO g wosoooagg eoogooooo 11 n «π o <pj λ * n * n O 'Π * i" iiii 1 i * s * »* E **„,%, g »3 * a * a * s * I §;> §: §5 SSSS32 §2 SS §2 §2 S2 §2 §2 r-ï o ü> 1 r — 1 tji Ö s _ _ Q) fö oo dj M m ld rl t? Tl £ +> w Ö1 7) (USO oooooooooooooooi> jjSo oo in in σι σι σι οι οι ci 01 01 £}

Snj + lCSCN-r-t dj S &> _ «^ o

H CS

(XI Kg rtj cs (β

EΗ · W

cs Di

H

O

(CS

O

r-i P

O 3 cs cs oo 1-1 co c ^ r ^ c ^ (0 ^ 1-1 1-4 2 & o

CS

S § co nn tninin. μ cs cs cs cs Di H O Di a hIo incooocooococooococoooco Q ^ (η iH «—I» —i »—I H 1-4 i-l 1-4 1-4 i-4 i-l 1-1 W Dl 'ff +)

O 0 W 0 CS N

φ I (31 in Dl 01 01 01 01 Ol 01 01 01 01 Ol Ol Λ + i cs cs cs cs cs CS cs cs cs cs cs cs cs cs O Λ 01 UI 0 Dl Ό a ^ enn 1 «m - 14 - σ 'σι θ' σ> σι O 'O' β β β O 'θ' β cc I Ö I · γΗ I · Ρ | · Ρ Ö I β I -PI · Η I · Ρ

• H + j -P + j -P -rt + J +) + J

β U-P U-P U-P U-P -p O -P U-P U-P U-P

dja + jeajeajaa) 4je + jaaja (uea) OiOd) ON ON ON OJOtUONONON

Ö 03 N IS g 03 β CO S NCONCOSCOSCOa • daoooaaooo · η 0 -η · η -r-i 0 -m 0 * n * n · γ * ι

p -Η -H df> -P OP r! dP -P Ή OP Ή <X> -P dP

0) Λ <#> Λ Λ Λ β Λ <x> £ 1 Λ Λ g ΟΟΟΦ ο ο ο ο ftom mo οο οο α> οο οο οο οο ο 00 * Η τ-Ί CM rH »d <* Η C5 CM CT > «D1« Η Ο ·> -ι CN * “Ι Η ο ο> 1 rp θ '_ β a ο ο 3 ο

CD Ρ CN

Η θ '> ι Λ -Ρ Η θ' (—1 ρ ο αο g ο ο ο ο οο ο ο ο> -Pido σι ο σι mo ο σι σι Ρ (Ö p * -Η rH * -Ι τΗ τ- Ηί-Ι ^ -Ιτ-Ι <α & σ £ Ρ3 ΡΙ Ο Η <Ν cq aa ri3 CM id

f · P

CN O 'r-1 u cd

YOU

h a U 3 m co m m

(Ö p «-I T-ι ΤΗ TH

g o '

O

CN

K „co g m • 3 cn p H O 'u o> a g h id m m m m co U p' —i * - '-—I -— <-— * g O'

M * + J Ο β Ui 0 CN N

W H g • oido cn σι o ones cn σι σι

Ν 'Λ Ρ Μ CN CN CN CNCN CN CN CN

Ο Λ 0>

Ui β θ 'Ό a ~ · in Ο Lf! Ο

CN

80 0 1 6 53 - 15 -

Table B and observations from attempts with concentrated solutions of the MgSO 2 and K 2 SO 2 containing double salt show that a method is possible in which only part of the magnesium values of the double salt are converted into anhydrous MgCl 2 in glycol. Unreacted double salt, unreacted potassium chloride and potassium sulfate produced by the exchange reaction, which are present in the precipitates in the above process steps, can be recycled to previous steps in the process while still obtaining the advantages of the invention.

The combination of the methods discussed above makes it possible to recover water-free magnesium chloride by simultaneous treatment of carnallite ore, as described above, and mixed sulfate ore containing magnesium and potassium values. The accompanying figure schematically shows a possible method for this treatment and isolation of high quality, high purity, anhydrous MgCl 2, which magnesium chloride is suitable for being fed into an electrolysis cell for the preparation of metallic magnesium. Anhydrous KCl and / or anhydrous K2 SO4 can be isolated by this method, depending on the treated relative amounts of both types of mixed ores.

In the accompanying figure, blocks represent the different steps discussed above in detail for the individual methods. The advantages of the combined process are obvious: First, only a single process step is required to isolate anhydrous MgCl2 from the MgCl2 · NHH / glycol slurry formed in both processes; This means that less equipment is needed and economic advantages are obtained. Secondly, the KCl obtained from the treatment of the carnallite as a by-product can advantageously be used as starting material in the exchange reaction required for the treatment of the mixed Mg / K sulfate. Finally, the combination of the two methods allows for a technical, process and economic variability that can be used advantageously depending on the price and availability of all starting materials.

The invention is not limited by the scheme shown in the attached figure, since numerous modifications are possible within the scope of the invention.

800 1 6 53

Claims (12)

A process for treating a carnallite-type mineral material to recover anhydrous MgCl 2 and KCl 1 therefrom, characterized in that: 5 (a) the carnallite ore is dissolved in the minimum amount of water required for complete dissolution, to obtain a carnallite solution; (b) filtering from the carnallite solution obtained in step (a) any residual precipitate, which is not soluble in the solution, filtering to obtain a filtered solution; (c) adding ethylene glycol to the filtered solution obtained in step (b) in an amount sufficient to dissolve all of the MgCl 2 contained in the filtered solution to obtain an ethylene glycol water carnallite solution; (D) remove water from the ethylene glycol water-camallite solution obtained in step (c) by distilling the water therefrom, to obtain an anhydrous solution of MgCl 2 in ethylene glycol, which can be up to about 2.0 wt% KCl and a precipitate of anhydrous potassium chloride, and then removes and isolates the precipitate from the solution of MgCl 2 in ethylene glycol to obtain an anhydrous solution of MgCl 2 in ethylene glycol; (e) to the anhydrous solution of MgCl 2 in ethylene glycol, anhydrous ammonia to form a precipitate of MgCl 4 OH, and filter the precipitate out of the solution, wash with a solvent for ethylene glycol, which solvent is of low molecular weight, and before washing the precipitate is saturated with anhydrous ammonia, and isolates the washed precipitate from anhydrous MgCl2.6NH2; (f) heating the MgCl2, δΝΗΝΗ, obtained in step (e) at a temperature sufficient to expel all the ammonia, to obtain anhydrous MgCl2. Process according to claim 1, characterized in that steps (a) and (c) are combined by adding water and ethylene glycol simultaneously to the carnallite and then steps (b), (d), (e) and ( f) performs. A method according to claim 1, characterized in that ethylene glycol is added to a hydrate water-containing carnallite to obtain a solution of carnallite in ethylene glycol, and then steps (b), (d), (e) and (f) performs. 4. Process for removing trace amounts of potassium chloride from 800 1 6 53 Γ - 17 - a glycol-moistened filter cake of MgCl 2 .eNH 2, characterized in that the cake is washed with methanol saturated with ammonia in an amount which sufficient to remove the potassium chloride and glycol from the cake. A process for treating a mixed salt containing potassium and magnesium sulfate to obtain anhydrous MgCl 2 and potassium sulfate, characterized in that: (a) a mixed salt (double salt) containing magnesium and potassium sulfate is dissolved in water at a temperature of 50 ° - 90 ° C and the residue is filtered from the solution; (b) adding a molar equivalent of potassium chloride to and dissolving in the filtered solution obtained in step (a), the molar equivalent being calculated. based on the chloride ions required for the dissolved magnesium cations; (C) heating the solution obtained in step (b) at a temperature of 50®-90®C for a period sufficient to allow a chemical equilibrium to be established, to obtain an equilibrated solution; (d) to the equilibrated solution obtained in step (c), add sufficient ethylene glycol to dissolve the entire calculated amount of MgCl 2 present in the solution, and then the 2 SO 2, which is addition of the ethylene glycol is precipitated, removed from the solution; (e) distilling water from the solution of step (d) to form an anhydrous MgCl 2 solution in ethylene glycol and a precipitate of K 2 SO 4 then removing the precipitate from the solution; (f) pooling the K 2 SO 2 precipitates of steps (d) and (e) and washing the combined precipitates with sufficient water maintained at a temperature below 70 ° C to react ethylene gly- 30 col, and the washed 1 SO 2 isolates; (g) treating the anhydrous solution of magnesium chloride in ethylene glycol obtained in step (e) with anhydrous ammonia to form an MgCl 2 ammonia complex which precipitates from the solution in ethylene glycol; (h) removing the complex precipitate from the ethylene glycol and washing with a low boiling ethylene glycol solvent to remove any ethylene glycol present in the precipitate; (i) heated the magnesium chloride-ammonia complex to displace ammonia, leaving completely anhydrous magnesium chloride as the final product. _ 800 1 6 53 - 18 - Process according to claim 5, characterized in that langbeinite is used as a source of the mixed salt containing potassium and magnesium sulphate. 7. Process according to claim 5, characterized in that leonite is used as a source of the mixed salt containing potassium and magnesium sulphate. Process according to claim 5, characterized in that it is used as a source of the mixed salt containing potassium and magnesium sulfate. 9. Process according to claim 5, characterized in that picromerite 10 is used as a source of the mixed salt containing potassium and magnesium sulfate. 10. Process according to claims 5-9, characterized in that the mixed salt is dissolved in a mixture of water and ethylene glycol at a temperature of 50®-90®C, any insoluble residue present is removed, and then steps (b) , (c) and (e) to (i). Process for the recovery of anhydrous MgCl 2 and anhydrous KCl 1 and / or anhydrous K 2 SO 2, characterized in that a combination of the process according to claim 1, 2 or 3 and the process according to one or more of claims 5 - 9 or claim 10. 12. Process according to claim 11, characterized in that the KCl obtained by treating a carnallite ore as a by-product is used as starting material in the process for the recovery of anhydrous MgCl 2 from mixed magnesium and potassium sulfate. 80 0 1 6 53