DE1592145C3 - Process for the preparation of practically completely anhydrous magnesium chloride from hydrated magnesium chloride - Google Patents

Description

3 4

If the temperature is treated with HCl gas at a higher temperature and then the water content is gradually reduced until the water vapor content of the HCl gas in contact is reduced to about 1 mole or less of water per mole of salt with the magnesium chloride, but with increasing hydrolysis on-value is held, is characterized in that occurs. As will be shown in the following, for the temperature in the chamber in the range of about 5 according to the invention, the hydrolysis is kept to the extent that 227 to 538 ° C, while a vapor is not disturbing, as the basic chloride stream of hydrochloric acid formed, which is about 1 until Mg (OH) Cl contains 10 percent by volume of water vapor by chlorination in the anhydrous salt, which in itself is MgCl. The water content of the known conditions of a fluidized bed process by "spraying of dried hydrate" can be introduced into the chamber until rens and that the io can be reduced to 5 percent by weight, with the water vapor content of the approximately 5 percent by weight of MgO emerging from the bed as a hydrolysis product of the steam flow by controlling the operating parameters. incurred, which is chlorinated in the surveyor according to the invention, including the chamber temperature of the driving to anhydrous MgCl _2.
When spray drying, the dehydrated water vapor content in the stream when it enters the salt in a finely divided state with a sub-chamber is at most equal to the equilibrium size in the range from preferably about 20 to the vapor pressure of magnesium chloride monohydrate at 100 μ receive. These particles are quite porous as the chamber temperature is maintained. and essentially completely gas-permeable and thus

From German patent 336 612, that for the fluidized bed process according to the invention

German Auslegeschrift 1071592, the Swiss 20 suitable.

Roman patent specification 349 582 and from "Wirbel- A preferred temperature range for the invented layer technology" by Dr. Ing. Franz Schytil, dung proper method is 260-343 ⁰ C. Springer Verlag, 1961, pp 93 and 94 are, though, the water content of the vapors to the DC-fluidized drying method is known, but equilibrium vapor pressure of Magnesiumchloridmonoist these publications no reference to Do not exceed a 25 hydrate, MgCl ₂ · H _{2 O.} This can be seen from the ent-magnesium chloride drying process. speaks the latter, as in Fig. 3 shown and in the fol-

Finally, from the USA patent, the use of fluidized bed process at a fluidized bed temperature of about 227 ° C. and a vapor pressure of no more than about 5 percent by volume H for drying or dewatering of magnets is discussed ₂ O and known for a siumchloridhydrates. In this method, the fluidized bed temperature of 288 ° C with a steam is, however, a high temperature pressure of no more than about 30 percent by volume H ₂ O, which leads to the melt of the product. with a corresponding deviation from this limit. The process features according to the invention are lower vapor pressure for temperatures which cannot be seen between the processes of the USA patent and are those specified above. As a result of the take. 35 Moisture removed from the fluidized bed gases of

The starting material for the inventive method of removing the particles of magnesium chloride hydrate is preferably obtained from a concentration of 25 to 30 percent by weight of _{the moisture content of the entering, centered aqueous solution of the salt, the approximately HCl-H 2 O gas in contact with these particles} of the salt, although it is increased, the moisture content of a slurry of hydrated salt gases is in the range of about 1 to 10%, such as MgCl ₂ · 6 H ₂ O, in water as well preferably 2 to 6 percent by volume of this HCl-H ₂ O- can be used. Such solutions or hydrates are vapors.

from sea water and salt lakes by evaporation and. In a preferred form of the process, the

selective precipitation of the various other ur- dehydration of the spray-dried

Injected salts, such as the sodium, 45 particulate product in the fluidized bed rather than continuous

Potassium and Calcium Chlorides and Sulphates, and Process in a Closed Cylindrical Retort

by the precipitation or conversion of primary or fluidized bed chamber with a perforated one

originally present magnesium sulphate in the distributor plate, which is used to create a space between

Chloride available. After such processes, the plate and base of the chamber can see the interior

concentrated solutions or hydrated salts 50 in the vicinity of the soil, through-

Made from naturally occurring magnesium chloride. The Chamber can click on the appropriate

Solutions containing only small amounts of other salts, dehydration temperature by means of electrical

such as those mentioned above, can be obtained. Resistance heating elements or by other common ones

A concentrated, aqueous magnesium chloride auxiliary is heated. The HCl-H ₂ O vapors solution or the slurry of hydrated 55 is passed through an inlet line in the chamber floor. Salt is then introduced to drying in a conventional and thence upwardly through the distributor spray dryer, the plate of heated gases at the top of the chamber is flowed through through an outlet, which is preferably drawn off an inlet or a discharge line. The particulate material, dried by temperature at about 538 ° C. and an outlet or spray, is the outlet temperature for the product that is continuously sprayed out of the spray dryer through dried product in the range from about 196 to a feeder with a gas seal, e.g. B. a 274 ° C depending on the degree of the desired star feeder, have a salt dehydration in the fluidized bed chamber. If the outlet is fed to form a fluidized bed of the product dried by spraying temperature in the area of the lower limit of the hung product, through the above area, then there is HCl-H ₂ O vapors upwards with such dried product by spraying 65 essentially from dihydrate to pass through that the material is fully MgCl ₂ · 2 H ₂ O. If the outlet temperature in Rieh is constantly whirled up and the particles therein are suspended to the above-mentioned upper limit. The particles that come from the

air-layer chamber fly away, enter through a line in the side wall in-the chamber at a point spatially separated from the inlet line, preferably diametrically opposite, a.

Because of the continuous supply of HCl-H ₂ O vapors through the basal inlet pipe into the fluidized bed chamber and because of the above-mentioned volume proportions of H ₂ O to HCl, a charging and recycling system is still required before the speed is increased beyond this, this can be caused by entrainment lead to high product losses. This effect can be achieved by partially precipitating the particles, passing between a pair of pressure rollers and then grinding to bring the rolled product back to a particle size in the range of about 20 to 1000 and preferably about 50 to 500μ. With the so obtained

seen. In this an aqueous solution of io precipitated product, much higher HCl can be fed from a storage tank into a steam-heated flow rate for the HCl-H ₀ O stripper with falling film
Vapors at around 93.3 ° C are fed to a condenser, in which they are cooled in such a way that
that they are above the condensate on the 15
Benen HCl-H ₂ O proportions can be set.
From there they are fed into the inlet feed pipe at the bottom of the fluidized bed chamber
and blown into the chamber. Be at the same time

the monitoring and recycling of the HCl-H ₂ O vapor, HCl-H ₂ O vapors, which are loaded with an excess of moisture, have been drawn off via the drain pipe at the top from the fluidized bed chamber used in the fluidized bed dehydration
are, inserted into another capacitor, in
which they are also cooled in such a way that they
above the condensate again on the volume 25
ratios of the HCl-HgO charge for the soil
the fluidized bed chamber can be adjusted. from
there they are fed into the via a heating element
Inlet pipe at the base of the fluidized bed chamber
fed to together with the aforementioned 30
Steaming from the feed source into the chamber
to be blown in.

In the present process, the ranges specified above for the ratio of H ₂ O to HCl,

in the vapors, which are pumped into the fluidized bed chamber 35, film 4, which carries a steam-heated jacket, which is supplied via steam line 5 and which is drawn off from it, and which has a condensate return line 6 with a view to the technically successful drainage. The procedure is in the scraper. When this ratio is below the aqueous acid solution at about 93.3 to 104.4 ° C about 1 percent by volume of water evaporates in the incoming. The HCl-H., O-vapors emerge from the HCl-H ₂ O-vapors, the cost of the 40 head of the scraper is located at about 93.3 ° C by lei-removing the excess moisture from tion 7 , while the condensate from the base of these vapors in the fluidized bed chamber absorber was scraper at about 104.4 ° C by a drain, too high and are then no longer pipe 8 in a cooler 9 for residual acid technically portable. During the treatment of is fed, in which it forms an aqueous magnesium chloride particle in the fluidized bed by 45 HCl solution with 21% by weight HCl, which is returned via the presence of at least 1% and preferably the pipe 10 in the storage tank 11 for at least 4% by volume Moisture in the standing acid is drained off, the HCl-H ₂ O vapors released to about 32.2 ° C are improved, since it is cooled.

this is a slight "agglomeration of the particles and the 93.3 ° C warm HCl-H _o 0 vapor from the

If the moisture content of the vapors is too high, it is fed via line 7 to the head of an overhead steam condenser 12, which is developed by the fluidized bed chamber, in which the temperature reaches the point of overagglomeration of the particles is reduced by a rate at which the water vapor content leads to a deterioration in the fluidized bed effect. Thus, the desired ratio of HCl to H ₂ O is set for which the preferred upper limit is set for the moisture vapors that are to be fed into the bottom of the eddy content of the exiting vapors at around 20 volume layer chamber. The desired volume ratio can be 5% for an additional percentage as above and optimally at around 12 volume. H ₂ O to 95% HCl, which is a weight ratio

As mentioned above, the particles of which partly _{correspond to 2.5 H 2} O to 95.5 HQ. The condensation temperature, which is dehydrated by spray drying and at which this magnesium chloride particle size and porosity ratio is obtained , is 62.5 ° C. The condenser 19 did, which is a practically complete dehydration (Fig. 1) with a water-cooled jacket through fluidized bed treatment in HCl-H ₂ O-GaS see, which is supplied with cold water, the steam flow In the case of these particles, pipe 13 enters and, via pipe 14, thin-shelled, hollow spheres relatively 65 emerge.

low density, so that it can be used at relatively low levels. The HCl-H ₀ O-

speed of the HCl-H ₂ O vapor flow in the condensate must be treated via pipe 15 in the scraper 4 fluidized bed. If there- returned (with falling film) while the

Vapors are used, resulting in an increase in the rate of production of the anhydrous Product results.

A detailed description of FIG. 1 to 3 given.

F i g. 1 and 2 show the method and apparatus for practicing the invention. F i g. 1 primarily illustrates the production, transfer

wherein the steps of previous spray drying and dehydration in the fluidized bed are included.

3 shows the relationship between temperature and maximum water content in the fluidized bed chamber, above which dehydration beyond the level of the monohydrate MgCl ₂ · H ₀ O does not occur.

To Fig. 1: Technical hydrochloric acid of 22 ° Be as a starting material for HCl vapors is in a container 1 lined with rubber is kept. From there it is via pump 2 through line 3 in the head of a scraper with falling

adjusted HCl-H, O vapors via line 16 and 17 a are fed into the foot of a fluidized bed chamber 17, wherein, as below with reference to Fig. 2 explains a continuously replenished fluidized bed of the partially dried by spraying dehydrated magnesium chloride is treated in the fluidized bed and in a stream of HCl-H ^ O vapors flowing upwards through the Fluidized bed is blown in, is further practically completely dehydrated.

The HCl-H ₂ O vapors exit from the top of the fluidized bed chamber 17 via line 18 at elevated temperatures after they have passed the fluidized bed with absorption of water and are fed from there into the top of a recycle condenser 19, wherein the temperature on the Value is lowered at which the excess moisture absorbed by the magnesium chloride hydrate is removed by condensation. This temperature is determined with reference to FIG. The condensate in the condenser 19 is drained through the pipeline 20 (FIG. 1) as an approximately 40% aqueous HCl solution and discharged into a storage container 21 and from there pumped via pump 21a and pipeline 22 into the scraper charging container 1. The vapors from the recycle condenser are adjusted to the correct HCl-HoO volume ratio for recycle in the fluidized bed chamber 17 and withdrawn via line 23 from the condenser 19 and from there through the heater 24 and the 'pipes 25 and 26 by means of a fan 27 for return and fed for injection into the foot of the fluidized bed chamber 17 through line 17 a, as shown in the drawing. The recycling condenser 19 is provided with a cooling jacket which is cooled with cold water which is fed in via pipe 28. The heater 24 heats the HCl — H, O vapors to the correct temperature for injection into the foot of the fluidized bed chamber 17.

To F i g. 2: An aqueous solution of magnesium chloride having a magnesium chloride concentration of about 25 to 30 percent by weight, or alternatively, a water slurry of hydrated magnesium chloride crystals, such as the hexahydrate MgCl ₀ 6H ₂ O, is fed to the spray dryer 50 through feed pipe 51 and through a connecting nozzle 52 in the form of a Spray mist 53 is blown into chamber 54 of the spray dryer. The dryer is heated by an inflow of hot air which is blown at about 538 ° C. into the base of the drying chamber 54 through pipe 55 from a heater 56. These gases exit the chamber 54 at about 196 to 343 ° C. through an outlet pipe 57 at the top of the chamber and pass into a dust separator 58 to remove "blown over" particles of the spray-dried product. The particles of the partially dehydrated and spray dried magnesium chloride fall into the base of the chamber 54 and are collected in the conical base 59 and from there pass through a downwardly inclined chute 60 containing a gas lock star feeder 61 and through the side wall into one upright, cylindrical fluidized bed chamber 17 enters. The blown product from the drying chamber 54, which passes through the upper outlet 57 into the dust separator 58, is separated from the gases therein and also passes downwards, following the force of gravity, through a pipe 62 which is connected to the chute 60.
Somewhat above the floor 63, the interior of the fluidized bed chamber 17 is spanned by a perforated distributor plate 64, which creates a space 65 between it and the floor of the chamber. In the chamber 17 are a number of electrical resistors

ao floor heating elements, e.g. B. 66, which are supplied by lines such as line 67, which are recessed in the wall of the fluidized bed chamber, and are in communication with a source of electrical energy (not shown). The incoming HCl-H ₂ O vapors, which are fed into the bottom or space of the fluidized bed chamber 17, are as described above with reference to FIG. 1 described, blown through the lines 16, 26 and 17 a. The HCl-H ₂ O vapors emerging from the fluidized bed chamber are drawn off through line 18 at the top.

The spray-dried particulate product 59 from the spray dryer is fed into the fluidized bed chamber 17 by the star feeder 61 and forms a fluidized bed 70 with the particles, which builds up to approximately the height shown and under the action of the HCl-H ₂ O- Vapors remain which are blown in through the inlet pipe 17a at the foot and from there pass through the distributor plate 64 upward through the fluidized bed 70 to fluidize and suspend the hydrated magnesium chloride particles therein and to dehydrate them practically to the anhydrous form. _{The HCl-H 2} O-GaSe, laden with excess moisture after passing through fluidized bed 70, flow upward through chamber 17 and are withdrawn through flue 18 for excess moisture removal and recycling, as described above with reference to FIG. The anhydrous magnesium chloride particles obtained from the dehydrating fluidized bed treatment flow out of the fluidized bed chamber via a downwardly inclined chute 71 which leaves the chamber through the side wall at a point, preferably diametrically opposite that of the charging chute 60. The discharge chute 71 opens into a melting device 72 to convert the released anhydrous magnesium chloride into the molten or liquid state. From there it flows through a drain pipe 73 into a mold 74 where ingots are poured for shipping and use.

To Fig. 3: The curve ^ 4 shows the change in the equilibrium vapor pressure of magnesium chloride monohydrate, MgCl ₂ · H ₂ O, with the temperature over a range of 5 to 30% H ₂ O vapor. What is remarkable about this curve is that when the H ₂ O vapor pressure, at an operating temperature chosen in the range shown, is equal to or higher than the corresponding HoO content as it is taken from the graph, the treated, hydrated magnesium chloride is only dehydrated to monohydrate. For a higher degree of dehydration, the H ₂ O percentage must be lower than the value read from the graph at the operating temperature in question. If z. B. the operating temperature 282 ° C and the volume percentage for H ₂ O-

409 515/373

Steam in the fluidized bed chamber is 20% or more, the hydrated magnesium chloride _{product is dehydrated upon treatment to the monohydrate containing 1 mole of H 2} O per mole of MgCl ₂ as shown in the graph. On the other hand, when the H ₂ O vapor percentage is lower than 20%, the anhydrous magnesium chloride is formed in the equilibrium state. Or more simply, if the temperature / percent Η, Ο relationship falls to the left of curve A , the dehydrated product will contain 1 mole or more of water per mole of MgCl ₂ , while the opposite is true when this relationship is on the right side of the graph falls. The course of the curve A can be expressed approximately mathematically, precipitation from alcoholic solution is obtained in a fluidized bed chamber on a perforated distributor plate by introducing HCI-H ^ O vapors containing 1 percent by volume of water for 14 minutes at a steam flow rate of 0.116 m per second and at temperatures of 266 to 299 ° C. The vapors emerging from the chamber contained 11.6 percent by volume H ₂ O. The analyzes of the feed material and the product obtained are as follows (percent by weight):

feed
product

Vo MgCl ₂

69.7
97.4

%> H ₂ O

26.7
1.0

VoMgO

3.6
1.6

⁰ A) H ₂ O = 5+ 25

1.8 T - 408
210

where T (° C) is the temperature from the graph.

Therefore, in order to be certain that the treated product is substantially completely dehydrated, the operating parameters of the process must be adjusted to be certain that the process is clearly on the right hand side of the curve in FIG. These operating parameters include the rate of feed of the hydrated product to the fluidized bed chamber, the residence time of that product in the chamber, the HCl: H ₂ O ratio of incoming and outgoing hydrochloric acid and water vapors, and the temperature in the fluidized bed zone.

The following examples illustrate the relative setting of the parameters for different selected ones Operating conditions and results:

example 1

Pure Magnesiumchloriddihydrat with a grain size of less than 0.15 mm was, as obtained by a result of HCl-H ₂ 0-Dehydration: The reduced H ₂ O content of the feed material was 26.7 to 1% and the MgO content of 3.6 decreased to 1.6%. The product recovered was essentially anhydrous MgCl ₂ of high purity.

Example 2

Hydrated magnesium chloride, as obtained by precipitation in the sun from the large salt lake in the USA, which contains small amounts of the chlorides of B, Ca, Na, K and Li as impurities, was dried by spraying and then as in Example 1 Introduction of HCl-H ₂ O vapors, the 2 percent by volume

Containing water, subjected to dehydration in a fluidized bed over a period of 82 minutes at a steam flow rate of 0.043 m per second and at temperatures of 260 to 310 ° C. The vapors emerging from the chamber contained 9.1 percent by volume H ₂ O. The analysis of the charge and the product recovered was as follows:

Vo Mg Vo B, Ca, Na, K, Li VoCl. Vo H ₂ O Vo MgO feed
product 16.06
18.34 8.67
9.82 59.19
70.00 15.4
1.6 1.7
0.6

The H ₂ O content was decreased from 15.4 to 1.6% and the magnesia content from 1.7 to 0.6% so that the product obtained was practically anhydrous and free from magnesia contamination. It should be mentioned that The Ca, Na, K and Li chlorides present in the product obtained are desired additives to the molten salt in the electrolytic production of metallic magnesium, since they increase the electrical conductivity or density of the bath and thus facilitate electrolysis.

Example 3

The same starting material and procedure were used as in Example 2, with the modification that the HCl-H ₂ O vapors contained _{3 percent by volume H 2} O when introduced into the fluidized bed chamber. The dehydration time in the fluidized bed chamber was 10 hours at a steam flow rate of 0.061 m per second and a temperature of 277 to 293 ° C. The vapors emerging from the chamber contained 7 percent by volume H ₂ O. The feed and the product recovered had the following analysis:

VoMg Vo B, Ca, Na, K, Li VoCl VoH ₂ O VoMgO feed
product 18.7
21.0 4.7
5.3 59.4
69.0 16.7
4.3 0.7
0.1

Accordingly, the H ₂ O content of the feed material was reduced from 16.7 to 4.3% and the MgO content from 0.7 to 0.1%.

Example 4

The same procedure and feed was used as in Example 3, _{except that the spray dried product was treated with HCl-H 2} O vapors containing 5% by volume H ₂ O when introduced over a period of 3 hours at a steam flow rate was dehydrated from 0.061 m per second and at a temperature of 277 to 293 ° C in a fluidized bed. The vapors emerging from the chamber contained 8.8 percent by volume H ₂ O. The feed and the recovered product had the following analysis:

% Mg VoB, Ca, Na, K, Li ° / o Cl % H ₂ O VoMgO feed
product 18.1
21.7 4.6
5.3 59.9
70.5 17.2
2.3 0.6
0.1

Accordingly, the H ₂ O content of the feed material was reduced from 17.2 to 2.3% and the MgO content from 0.6 to 0.1%.

Example'5

The same procedure and starting material was used as in Example 4, _{except that the spray-dried product was treated with HCl-H 2} O vapors containing 7 percent by volume of H ₂ O when introduced for a period of 7 hours at a Steam flow rate of 0.061 m per second and at a temperature of 277 to 293 ° C was subjected to a fluidized bed dehydration. The vapors emerging from the chamber contained 11 percent by volume H ₂ O. The analysis of the charge and the product recovered was as follows:

• / «Mg ° / oB, Ca, Na, K, Li o / oCl Vo H ₂ O Vo MgO feed
product 18.5
20.7 4.7
5.6 60.0
69.8 16.5
3.6 0.5
0.4

Accordingly, the H ₂ O content of the feed was decreased from 16.5 to 3.6% and the MgO content was decreased from 0.5 to 0.4%.

1 sheet of drawings

Claims (4)

1 2-like process is expensive, however, and the sources of patent claims: for the supply of naturally occurring magnesium oxide are limited. In contrast, hydra- 1. Process for the production of practically tized magnesium chloride all over the world readily available completely anhydrous magnesium chloride from 5, e.g. B. by precipitation from salt lakes and hydrated magnesium chloride, in which one from salt deposits, which were formed in the past by bedding of hydrated magnesium chloride in the vaporization of lakes under solar radiation from the form of small particles in a chamber near inland lakes. The hydrahigh temperature thus obtained is treated with HCl gas tized form is usually the hexahydrate with and the water vapor content of the HCl gas in the io 6 molecules of crystal water, MgCl ₂ · 6 H ₂ O. Four contact with the magnesium chloride on one water molecule can from the Hexahydrate is kept by a low value, characterized in that drying at elevated temperature by 204 ° C below indicates that the temperature in the formation of the dihydrate MgCl ₂ · 2H ₂ O is eliminated in the range of about 227 to 538 ° C. However, on further heating, in an effort to maintain a vapor stream of 15% to remove the residual water, decomposition and hydrochloric acid, which about 1 to 10 volume hydrolysis occurs, with the result that the anhydrous percent contains water vapor, per se - Magnesium chloride and the basic magnesium known conditions of a fluidized bed process hydroxychloride Mg (OH) Cl are formed. rens is introduced into the chamber and that the dehydration of the dihydrate can therefore occur Water vapor content of from the bed 20 MgCl ₂ · 2 H ₂ O austreten- not simply by heating without the steam flow by controlling the operating significant "decomposition, hydrolysis and the formation of parameters including the chamber temperature, Mg (OH) Cl are reached. It can however, due to the charging speed of the particles drying in an atmosphere of dry and the water vapor content in the stream with the HCl gas, which _{removes the H 2} O without hydrolysis, entry into the chamber at most equal to 25. But the later separation of the equilibrium vapor pressure of magnesium chloride of the water from HCl for its recovery in trokrid monohydrate at the chamber temperature reduced state and for recycling requires extensive and complicated equipment as well 2. The method according to claim 1, characterized by expensive measures, such as the distillation or the marking that the hydrated particles 3 ° turn of concentrated sulfuric acid,
are continuously fed into the chamber So describes the German patent specification 1102 122 and the dehydrated particles continuously a process for the production of anhydrous Maaus are removed from it. magnesium chloride, in which in a first stage a 3. The method according to any one of the preceding concentrated magnesium chloride solution of a spray claims, characterized in that the 35 is subjected to evaporation. In a second The water vapor content of the stage escaping from the bed is left in the spray-dried, still water-vapor stream by cooling to the area containing magnesium chloride in a countercurrent of 1 to 10 percent by volume, dry hot hydrogen chloride gas is reduced by a and then the steam flow is returned and chute furnaces fall. Where is the temperature is reinserted into the bed. 40 of the dry hydrogen chloride stream so high that 4. The method according to any one of the preceding, the falling magnesium chloride particles in the Claims, characterized in that the lowermost zone melts. Since the melting point of Fluidized bed chamber is at a temperature of anhydrous magnesium chloride at 718 ° C, about 260 to 343 ° C, which must be the temperature of the entering dry Vapor flow on entering the bed about 45% hydrogen chloride gas well above this temperature Contains 2 to 6 percent by volume of water vapor. stand. This method has the above Filings associated with a process in which anhydrous hydrogen chloride gas for dewatering magnesium chloride 50 is turned. Another process in which magnesium The invention relates to the preparation of anhydrous magnesium chloride, which is essential in the chloride, using a dry chlorine substance. It is dewatered by the hydrogen stream creates an improved method for obtaining German patent 748 089 known. Also the same from concentrated aqueous magnesium 55 ses process has the aforementioned chloride solutions or from one of the various disadvantages. hydrated, crystalline forms of magnesium according to the invention became a relatively simple and chlorides, such as B. the hexahydrate MgCl ₂ · 6 H ₂ O, economical process for the production of im those from such solutions on evaporation and essentially anhydrous magnesium chloride Failure to dry. 60 concentrated aqueous solutions or from these An essentially anhydrous magnesium, which can be obtained by evaporation and precipitation, Chloride is particularly suitable for electrolytically her- ted salts without the use of dry magnesium is required. HCl found as a dehydrating agent. Completely anhydrous magnesium chloride can be obtained by the process according to the invention for the production Chlorination of magnesium oxide at elevated temperatures of practically completely anhydrous magnesium temperature in the presence of carbon or carbon chloride from hydrated magnesium chloride material-producing compounds such as carbon monoxide and a bed of hydrated magnesium chloride and carbon tetrachloride. One of those in the form of small particles in a chamber at