WO2012163791A1

WO2012163791A1 - Method for manufacturing a lithium chloride solution from brine

Info

Publication number: WO2012163791A1
Application number: PCT/EP2012/059689
Authority: WO
Inventors: Julie BERNARDI; Yves Le Quesne; Antoine GOUZE
Original assignee: Eramet
Priority date: 2011-05-27
Filing date: 2012-05-24
Publication date: 2012-12-06
Also published as: FR2976280A1; AR086547A1

Abstract

The invention relates to a method for producing a lithium chloride solution from brine containing lithium, characterized in that the separation of lithium chloride from the other components of the brine containing lithium is carried out using an ion-exchange resin arranged in at least one column (1, 2, 3, 4, 5, 6), and in that said separation is carried out using the sequential simulated moving bed (SMB) method.

Description

Process for producing a lithium chloride solution from a brine

The invention relates to the production of a solution of lithium chloride from brine collected in a salt lake and rich in magnesium sulfate.

Lithium is a metal whose industrial importance is growing because of its use in batteries, especially for laptops, mobile phones, and soon electric vehicles. Although not strictly speaking, it is present in the earth's crust only in dispersed form, exploitable in a very limited number of regions of the world. The main sources of lithium are:

volcanic rocks such as pegmatites, where lithium is present in the form of silicates (spodumene, in particular);

- brines from ancient saline lakes called "salars", in which lithium is in the form of LiCl chloride, mixed with other salts of alkali and alkaline earth metals; such salars are found mainly in Tibet and South America, between the two chains constituting the Andes Cordillera.

It is this latter mode of lithium source which is concerned by the invention. Indeed, when one wants to obtain pure lithium as final product, the treatment of the volcanic rocks is not generally an appropriate method because it leads first to obtain Li0 ₂ which must be grilled, lixivier and treated chemically. This is too expensive, and the treatment of volcanic rocks is generally reserved in case it is desired to obtain lithium in oxide form for use in ceramics or glasses.

Salars are old salt-water lakes, consisting of a porous salt crust 10 to 400 m thick, within which a brine, that is, water saturated with NaCl (approximately 250 g / l) which also contains lithium (0.3 to 1.5 g / l), potassium (at a rate of approximately 30 g / l KCl), magnesium, calcium, sulphates . Depending on the geological environment, the ratio S0 ₄ / Li varies from 2 to 30 and the ratio Mg / Li varies from 3 to 25.

To recover lithium from salars, the brine is pumped through a borehole in the salt layer and treated to produce Li ₂ CO ₃ or LiCl ₃ , leaving it in the open air in ponds. where the water evaporates easily due to the low rainfall, the high altitude, the sunshine and the intensity of the winds typical of the regions where the salars are.

In a first basin where the initial brine is poured whose concentration of lithium (and also boron) is of the order of, for example, 1 g / l, the sodium chloride is mainly precipitated. The rest of the brine is poured into a second basin where the majority of the precipitation of KCl occurs. The remainder of the brine is poured into a third basin where the precipitation of potassium and magnesium salts predominates. Evaporation takes place until approximately 99.5% of the water in the initial brine has evaporated, followed by separation steps of boron, magnesium and calcium, before obtaining carbonate or lithium chloride of high purity.

This conventional method, however, does not give completely satisfactory results under all circumstances, depending on the precise composition of the brines, especially their levels of sulfate ions and magnesium. When the ratio S0 ₄ / Li is high (which is the case of many salars), there is crystallization of mixed sulphates including Li, K and Mg. The Li sulphate mixes with the subsequent precipitates and the Li contained therein (which can be up to 90% of the total Li of the brine) can only be recovered by selective dissolution of these precipitates, at a high cost. When the Mg / Li ratio is high, crystallization of magnesium salts is observed at the end of evaporation, at a stage where the concentration of the brine in Li is high (approximately 40 g / l), and the salt recovered is strongly impregnated by this brine. This leads to significant losses of Li.

To overcome these drawbacks, it may therefore be necessary to carry out selective separations Li / Mg and Li / S0 ₄ . WO-A-2010/006366 discloses such a method.

Thus, as mentioned, lime (Ca (OH) ₂ treatment can be practiced to precipitate sulphates in the form of gypsum and Mg as magnesium hydroxide. However, the process requires a large amount of reagents and produces additional solid residues which must be reprocessed, so that for high ratios Mg / Li or S0 ₄ / Li the operation is not economically profitable.

Another solution is to treat the brine with CaCl ₂ to obtain CaSO ₄ which precipitates and MgCl ₂ which remains in solution. The results are good, but this process is expensive because of the high cost of CaCl ₂ , and it does not eliminate the magnesium content in brines.

Finally, electrodialysis separation of LiCl and MgSO ₄ through membranes can be imagined. This process is efficient, but expensive in electricity that it is, in general, hardly possible to produce on the salar, and requires a large amount of membranes to treat the brine of a salar. Its economic profitability for a production of LiCI on an industrial scale is therefore debatable. The object of the invention is to propose a method for separating LiCl and MgSO ₄ contained in a brine which is both effective and economically viable.

For this purpose, the subject of the invention is a process for producing a lithium chloride solution from a lithiated brine, characterized in that the separation of lithium chloride from the other components of the lithiated brine is carried out. by means of an ion exchange resin disposed in at least one column, and said separation is effected by means of a plurality of simulated moving bed (SMB) columns.

Said separation can be performed according to the simulated sequential moving bed (SSMB) method.

It is then possible to use an installation comprising N columns enclosing the resin with N 4 4, so as to allow the creation of four zones placed in series in which a brine circulates, the exit of the zone 4 being connected to the entrance of the zone 1, and in which:

for Zone 1, an elution brine is introduced therein and an extract is extracted containing, in a preferred manner, lithium chloride;

for zone 2, the brine circulating in the plant is purified, by storing in a preferred manner the products with high affinity for the resin, preferentially LiCl, and by increasing the concentration of the brine in low affinity products for the resin, preferentially MgSO ₄ , so as to form a raffinate without adding or removing material;

for zone 3, the lithiated brine to be purified is introduced therein and the raffinate is removed, by storing in a preferred manner the products with a high affinity for the resin;

for zone 4, the brine is circulated without adding or removing material. At least one of said zones may comprise a plurality of columns.

Zone 1 and zone 4 may then each comprise a column, and zone 2 and zone 3 may each comprise two columns.

For each cycle of treatment of the brine, one can realize as many steps as there are columns, namely:

a first step in which the lithiated brine is introduced into the upper part of the first column of the third zone, the raffinate is extracted from the lower part of the last column of the third zone, said first stage comprising:

^* A first sub-step is carried out where an injection of a volume of brine lithiated in the upper part of the first column of the third zone is recovered an equivalent volume of raffinate in the lower part of the last column of the third zone , we inject a volume of elution brine in the upper part of the first column of zone 1, the same volume of extract is recovered in the lower part of the last column of zone 1, and brine is not circulated in zones 2 and 4;

^* A second sub-step in which then connects the first, second and third zones by isolating the zone 4, is injected an eluting volume of brine into the upper portion of the first column of the area 1, and recovering the same raffinate volume in the lower part of the last column of zone 3;

^* A third sub-step which is circulated in the loop brine already present in said N columns through the four zones, the brine discharged from zone 4 being fed at the beginning of zone 1;

and N-1 subsequent steps between which the functions of the different columns (1, 2, 3, 4, 5, 6) of rank n with 1 <n <N are shifted by circular permutation, the column of rank n fulfilling the function that filled the column of rank n-1 in the previous step and the column of rank 1 fulfilling the function that filled the column of rank N in the previous step.

The resin may be a strongly acidic cationic resin comprising at least sulfonic groups and having a particle size of between 200 and 800 μηι.

The resin may be a cationic resin containing at least sulfonic groups and together acidic and basic groups, and having a particle size of between 200 and 800μηι.

According to a variant of the process:

the quantity of brine feeding zone 1 is greater than or equal to 1.0 times the volume of the resin bed (BV) in each column of zone 1;

the amount of brine feeding line 2 is between 0.5 and 1.0 times the volume of the resin bed (BV) in each column of zone 2;

the quantity of brine feeding zone 3 is between 0.6 and 1.0 times the volume of the resin bed (BV) in each column of zone 3;

the quantity of brine feeding zone 4 is between 0.1 and 0.5 times the volume of the resin bed (BV) in each column of zone 4.

The temperature at which the process is performed can be between 10 and

80 ° C, preferably between 20 and 60 ° C.

The elution brine may have a dissolved solids concentration that differs by plus or minus 100 g / l from the dissolved solids content of the lithiated brine. Prior to introduction of the lithiated brine, the resin was preferably stabilized by residence in NaCl brine or NaCl brine circulation through the column (s).

The volume of the resin bed or beds (BV) with respect to which the amounts of brine are measured is preferably the volume of the resin bed (s) after stabilization by said NaCl brine.

As will be understood, the process according to the invention is based on a principle identical to that of chromatography on ion exchange resin. By passing a brine concentrated in Li in a column containing an ion exchange resin with the aid of an eluent, the retentions of the different elements present in the brine are different and various solutions are collected at various times in the process. enriched in one or more of the constituents (Li, Mg, sulphates) which it is desired to separate. The separation can be performed in a simulated moving bed (SMB process), and preferably in the simulated sequential moving bed method (SSMB), which is practiced in fields such as pharmacy and pharmacy. agrochemicals. (see JP-A-3,924,700, US-A-5,770,087, EP-A-2,027,762).

The invention will be better understood on reading the description which follows, given with reference to the appended figures 1 to 6 which show the functions of the columns of the installation used during the different steps of an example of the method according to the invention, in the case where there are six columns filled with resin.

By way of example, an example of implementation of the process according to the invention, applied to a brine rich in Li and containing of the order of 200 to 300 g / l of dissolved salts, will be described.

It is preferable to use a strongly acidic cationic resin having at least sulfonic groups, and having a precise particle size of between 200 and 800 μm, so that the Li atoms can be housed between the grains as exclusively as possible. Resins commercially available under the references DOWEX 99/310 (sulfonated polystyrene divinylbenzene resin from DOW CHEMICAL), FINEX CS16GC (sulfonated polystyrene divinylbenzene resin from FINEX), DOWEX MONOSPHERE C-600B (sulfonated styrene-butadiene vinyl ester resin) of DOW CHEMICAL), DOWEX MONOSPHERE C-350 (sulfonated polystyrene divinylbenzene resin from DOW CHEMICAL) or DOWEX MARATHON MSC (sulfonated polystyrene divinylbenzene resin from DOW CHEMICAL) are examples of such resins. The Li-rich brine (lithiated brine) is obtained by dilution with distilled water of a raw Li brine containing more than 400 g / l of dissolved solids. The dilution produces a brine containing 200-300 g / l of dissolved solids, a total concentration similar to that of the soda brine that will be used for the elution of the resin. It has been found during testing that it is generally beneficial for the treated lithiated brine to have a dissolved solids concentration comparable to that of the elution brine, ie it differs only by ± 100g / l. In this way, it is avoided to cause significant variations in the volume of the resin, which would be unfavorable to the proper functioning of an industrial installation. Also, it avoids the formation of precipitates in the resin which would reduce its performance. If experience shows or suggests that treating the crude lithiated brine with a given elution brine could cause such operating problems, it is therefore recommended to proceed with the treatment prior to a dilution of the crude lithiated brine with water. Table 1 summarizes an example of the partial compositions of these three brines.

Table 1: Analysis of brines used in tests

It should be understood that these concentrations represent only a particular non-exclusive example of implementation of the method according to the invention, and other compositions will also be used in the tests to be described.

To separate and collect the Li from the other components of the lithiated brine, a separator operating according to the SSMB principle is used. This separator is divided into four distinct zones, each comprising at least one column filled with resin. The brine that exits through the bottom of a column is injected into the upper part of the next column, and the columns are thus connected in series to form a loop, the lower part of the last column being connected to the upper part of the column. the first column. Zone 1 is located between the inlet of the eluent and the outlet of the extract. It makes it possible to recover, thanks to its entrainment by the eluent, the high-affinity component for the resin, in this case Li, in a liquid called Γ "extract".

Zone 2 is located between the outlet of the extract and the entry into the loop of the lithiated brine to be purified. It allows high affinity products to be stored for the resin and low affinity products for the resin to be removed. It is therefore a purification zone. No addition or withdrawal of liquid is made.

Zone 3 is located between the entry in the loop of the lithiated brine to be purified and the exit of the raffinate. It makes it possible to store the high affinity product for the resin. It is therefore also a purification zone. It makes it possible to recover the low-affinity component for the resin, in this case MgSO ₄ , in a liquid called "raffinate".

Zone 4 is located between the raffinate outlet and the inlet of the eluting brine eluent. It is a buffer zone that avoids contamination of the product containing the resulting lithium. No addition or withdrawal of liquid is made.

In summary, zone 1 makes it possible to elute the extract (most retained product), zone 2 makes it possible to adsorb the extract on the resin and to elute the raffinate, zone 3 makes it possible to adsorb the extract and to elute the raffinate, and the zone 4 makes it possible to adsorb both the extract and the raffinate.

According to the principle of the SSMB method, the different columns change their role by circular permutation during six successive steps (one per column), so as to optimize the recovery of Li in the extract and to regenerate the resins filling the columns. This change of roles makes it possible to simulate a displacement against the current of the fluid with respect to the resin.

In the example described, the installation is equipped with six columns 1, 2, 3, 4, 5, 6 each 25 mm in diameter and 1 m long, and containing about 480 ml of a resin A, which is a strong cationic resin having at least sulfonic groups. Zone 1 comprises a column 1, zones 2 and 3 each comprise two columns 2, 3 and 4, 5 put in series, and zone 4 comprises a column 6. The fact that zones 2 and 3 each comprise two columns allows to increase their power of separation between the different elements, this separation taking place mainly at their level. The system is fed by two pumps, one for feeding eluent (soda brine) and the other for supplying lithiated brine. These pumps are controlled by a derivative integral proportional regulator (PID regulator), taking the flow rate measured at the output as the reference flow rate. The six columns 1, 2, 3, 4, 5, 6 are connected in series and are each equipped with five valves and pipes on which the valves are arranged: - two inlet valves, one for the supply of lithiated brine, the other for the supply of eluent;

- two outlet valves, one used for the recovery of the extract, the other for recovery of the raffinate;

and a valve controlling the connection of the column with the next column.

Figure 1 shows schematically the installation, as used in the first of the six steps of the described example of treatment according to the invention.

In this first step, the first zone is constituted by the first column 1, the second zone is constituted by the second column 2 and the third column 3, the third zone is constituted by the fourth column 4 and the fifth column 5, and the fourth zone is constituted by the sixth column 6. All these columns 1, 2, 3, 4, 5, 6 are put in series by lines 7, 8, 9, 10, 1 1, 12 which each connect the lower part of a column of rank n at the top of the column of rank n + 1. The last pipe 12 connects the lower part of the sixth column 6 to the upper part of the first column 1. It is on these lines 7, 8, 9, 10, 11, 12 that are arranged the valves controlling the connection of the columns discussed above.

In this first step, the lithiated brine, containing in particular Li, Mg, SO ₄ and B, is introduced from a reservoir 13 in the upper part of the fourth column 4, therefore at the beginning of the third zone. In this third zone, the beginning of the separation between Mg and Li occurs. Since Li is more importantly retained than Mg in the resin, Li is favorably retained in the upper part of column 4 and Mg is retained in a controlled manner. preferred and less than Li, in the lower part of column 5. It is therefore possible to extract from the third zone, in this case in the lower part of the fifth column 5, a brine which has been removed from the essential of its initial content in Li and which contains only a fraction of its initial contents in Mg, S0 ₄ and B. Part of this brine purified in Li and rich in Mg (the raffinate) is extracted from the circuit by a line 14, and the remainder is brought into the upper part of column 6 constituting the fourth zone.

This fourth zone serves as a buffer zone between zones 3 and 1. It is located between the exit of the raffinate and the entrance of the eluent (sodium brine) and avoids the mixture between the rich Mg raffinate and the rich Li extract.

In a first substep, an injection of lithiated brine is made at the beginning of zone 3 (top of column 4) from the tank 13, and an equivalent volume of raffinate is recovered at the outlet of this zone 3 (bottom of the column 5). In parallel, a volume of eluent is injected at the beginning of zone 1 (top of column 1) from a reservoir 15 and an identical volume of extract rich in Li is recovered at the outlet of zone 1 (bottom of column 1). There is no brine circulation in Zones 2 and 4.

In a second substep, zones 1, 2 and 3 are connected in series, while zone 4 remains isolated. At the beginning of zone 1, a given eluent volume is injected, and, after passing through zone 2, the same volume is recovered in the form of a raffinate at the outlet of zone 3 via a pipe 16.

In a third substep, the volume of brine already present in the entire installation is circulated in a loop, the brine leaving zone 4 being reinjected at the top of zone 1.

Figure 2 shows schematically the installation, as used in the second of the six steps of the treatment example according to the invention.

In this second step, the first zone is constituted by the second column 2, the second zone is constituted by the third column 3 and the fourth column 4, the third zone is constituted by the fifth column 5 and the sixth column 6, and the fourth zone consists of the first column 1. With respect to the first step, the functions of columns 1 to 6 of a row have been shifted, as will be done between each of the other steps.

In this second step, the lithiated brine containing Li, Mg, SO ₄ and B is introduced from the tank 13 in the upper part of the fifth column 5, thus at the beginning of the third zone. In this third zone is the beginning of the separation between Mg and Li. Since Li is more importantly retained than Mg in the resin, Li is favorably retained in the upper portions of columns 5, 6 and Mg is retained from preferred way and less than Li, in the lower parts of the columns 5, 6. It is therefore possible to extract from the third zone, in this case in the lower part of the sixth column 6, a brine which has been freed from most of its initial content in Li and which contains only a fraction of its initial contents in Mg, S0 ₄ and B. Part of this brine purified Li and rich in Mg is extracted from the circuit by a pipe 17 and the remainder is brought into the upper part of column 1 constituting the fourth zone.

In a first substep, an injection of lithiated brine is made at the beginning of zone 3 (top of column 5), and an equivalent volume of raffinate is recovered at the outlet of this zone 3 (bottom of column 6). In parallel, a volume of eluent is injected from the reservoir 15 at the beginning of zone 1 (top of column 2) and an identical volume of extract at the outlet of zone 1 (bottom of column 2) is recovered by a 18. There is no circulation of liquid in zones 2 (columns 3 and 4) and 4 (column 1). In a second substep, zones 1, 2 and 3 are connected in series, while zone 4 remains isolated. At the beginning of zone 1, a given eluent volume is injected, and, after crossing zone 2, the same volume is recovered in the form of a raffinate at the outlet of zone 3 (column 6).

Figure 3 shows schematically the installation as used in the third of the six steps of the treatment example according to the invention.

In this third step, the first zone is constituted by the third column 3, the second zone is constituted by the fourth column 4 and the fifth column 5, the third zone is constituted by the sixth column 6 and the first column 1, and the fourth zone is constituted by the second column 2. Compared to the second step, we have shifted the functions of columns 1 to 6 of a row.

In this third step, the lithiated brine containing Li, Mg, SO ₄ and B is introduced from the tank 13 in the upper part of the sixth column 6, thus at the beginning of the third zone. In this third zone is the beginning of the separation between Mg and Li. Since Li is more importantly retained than Mg in the resin, Li is favorably retained in the upper part of columns 6, 1 and Mg is retained from preferential way and less than Li, in the lower parts of columns 6, 1. It is therefore possible to extract from the third zone, in this case in the lower part of the first column 1, a brine which has been freed of most of its initial content in Li and which contains only one fraction of its initial contents in Mg, S0 ₄ and B. Part of this brine purified Li and rich in Mg is extracted from the circuit by a pipe 19, and the remainder is brought into the upper part of column 2 constituting the fourth zoned.

In a first substep, an injection of lithiated brine is made at the beginning of zone 3 (top of column 6), and an equivalent volume of raffinate is recovered at the outlet of this zone 3 (bottom of column 1). In parallel, a volume of eluent is injected from the reservoir 15 at the beginning of zone 1 (top of column 3) and an identical volume of extract at the outlet of zone 1 (bottom of column 3) is recovered by a pipe 20. There is no circulation of liquid in zones 2 (columns 4 and 5) and 4 (column 2).

In a second substep, zones 1, 2 and 3 are connected in series, while zone 4 remains isolated. At the beginning of zone 1, a given eluent volume is injected, and, after passing through zone 2, this same volume is recovered in the form of a raffinate at the outlet of zone 3 (column 1) via line 19. In a third substep, the volume of brine already present in the entire installation is circulated in a loop, the brine leaving zone 4 being reinjected at the top of zone 1.

Figure 4 shows schematically the installation, as used in the fourth of the six steps of the treatment example according to the invention.

In this fourth step, the first zone is constituted by the fourth column 4, the second zone is constituted by the fifth column 5 and the sixth column 6, the third zone is constituted by the first column 1 and the second column 2, and the fourth zone consists of the third column 3. Compared to the third step, the functions of columns 1 to 6 of a row have been shifted.

In this fourth step, the lithiated brine containing Li, Mg, SO ₄ and B is introduced from the tank 13 in the upper part of the first column 1, thus at the beginning of the third zone. In this third zone is the beginning of the separation between Mg and Li. Since Li is more importantly retained than Mg in the resin, Li is favorably retained in the upper parts of columns 1, 2 and Mg is retained from preferential way and less than Li, in the lower parts of columns 1, 2. It is therefore possible to extract from the third zone, in this case in the lower part of the second column 2, a brine which has been freed from most of its initial content in Li and which contains only a fraction of its initial contents in Mg, S0 ₄ and B. Part of this brine purified Li and rich in Mg is extracted from the circuit by a pipe 21 , and the remainder is brought into the upper part of column 3 constituting the fourth zone.

In a first substep, an injection of lithiated brine is made at the beginning of zone 3 (top of column 1), and an equivalent volume of raffinate is recovered at the outlet of this zone 3 (bottom of column 2). In parallel, a volume of eluent is injected from the tank 15 at the beginning of zone 1 (top of column 4) and an identical volume of extract at the outlet of zone 1 (bottom of column 4) is recovered by a pipe 22. There is no circulation of liquid in zones 2 (columns 5 and 6) and 4 (column 3).

In a second substep, zones 1, 2 and 3 are connected in series, while zone 4 remains isolated. At the beginning of zone 1, a given eluent volume is injected, and, after passing through zone 2, this same volume is recovered in the form of a raffinate at the outlet of zone 3 (column 2) via line 21.

In a third substep, the volume of brine already present in the entire installation is circulated in a loop, the brine leaving zone 4 being reinjected at the top of zone 1. FIG. 5 schematizes the installation, as used in the fifth of the six steps of the treatment example according to the invention.

In this fifth step, the first zone is constituted by the fifth column 5, the second zone is constituted by the sixth column 6 and the first column 1, the third zone is constituted by the second column 2 and the third column 3, and the fourth zone is constituted by the fourth column 4. Compared to the fourth step, we have shifted the functions of columns 1 to 6 of a row.

In this fifth step, the lithiated brine containing Li, Mg, SO ₄ and B is introduced from the tank 13 in the upper part of the second column 2, thus at the beginning of the third zone. In this third zone is the beginning of the separation between Mg and Li. As Li is more importantly retained than Mg in the resin, Li is favorably retained in the upper part of columns 2, 3 and Mg is retained from preferred way, and less than Li, in the lower parts of columns 2, 3. It is therefore possible to extract from the third zone, in this case in the lower part of the third column 3, a brine which has been removed the bulk of its initial content in Li and which contains only a fraction of its initial contents in Mg, S0 ₄ and B. Part of this brine purified in Li and rich in Mg is extracted from the circuit by a pipe 23, and the remainder is brought into the upper part of column 4 constituting the fourth zone.

In a first substep, an injection of lithiated brine is made at the beginning of zone 3 (top of column 2), and an equivalent volume of raffinate is recovered at the outlet of this zone 3 (bottom of column 3). In parallel, a volume of eluent is injected from the tank 15 at the beginning of zone 1 (top of column 5) and an identical volume of extract at the outlet of zone 1 (bottom of column 5) is recovered by a 24. There is no circulation of liquid in zones 2 (columns 6 and 1) and 4 (column 4).

In a second substep, zones 1, 2 and 3 are connected in series, while zone 4 remains isolated. At the beginning of zone 1, a given eluent volume is injected, and, after passing through zone 2, this same volume is recovered in the form of a raffinate at the outlet of zone 3 (column 3) via line 23.

Figure 6 schematizes the installation, as used in the sixth of the six steps of the treatment example according to the invention.

In this sixth step, the first zone is constituted by the sixth column 6, the second zone is constituted by the first column 1 and the second column 2, the third zone consists of the third column 3 and the fourth column 4, and the fourth zone is constituted by the fifth column 5. Compared with the fifth step, the functions of the columns 1 to 6 d have been shifted. 'rank.

In this sixth step, the lithiated brine containing Li, Mg, SO ₄ and B is introduced from the reservoir 13 in the upper part of the third column 3, thus at the beginning of the third zone. In this third zone is the beginning of the separation between Mg and Li. Since Li is more importantly retained than Mg in the resin, Li is favorably retained in the upper part of columns 3, 4 and Mg is retained from preferred way and less than Li, in the lower parts of columns 3, 4. It is therefore possible to extract from the third zone, in this case in the lower part of the fourth column 4, a brine which has been freed from the bulk of its initial content in Li and which contains only a fraction of its initial contents in Mg, S0 ₄ and B. Part of this brine purified Li and rich in Mg is extracted from the circuit by a pipe 25 and the remainder is brought into the upper part of column 5 constituting the fourth zone.

In a first substep, an injection of lithiated brine is made at the beginning of zone 3 (top of column 3), and an equivalent volume of raffinate is recovered at the outlet of this zone 3 (bottom of column 4). In parallel, a volume of eluent is injected from the reservoir 15 at the beginning of zone 1 (top of column 6) and an identical volume of extract at the outlet of zone 1 (bottom of column 6) is recovered by a 26. There is no circulation of liquid in zones 2 (columns 1 and 2) and 4 (column 5).

In a second substep, zones 1, 2 and 3 are connected in series, while zone 4 remains isolated. At the beginning of zone 1, a given eluent volume is injected, and, after passing through zone 2, this same volume is recovered in the form of a raffinate at the outlet of zone 3 (column 4) via line 25.

Once these six steps have been completed, the installation can start working again from the first step.

In other words, the general principle of the invention is based on the passage of the lithiated brine to be treated in four successive zones, comprising in total a number N of columns (N may be greater than 4) preferably filled with a cationic resin strongly acid having at least sulfonic groups, and having a particle size of 200-800 μηι. An N number of stages of treatment of the lithiated brine is carried out, by shifting by one unit between each step the function of each column of rank n (with 1 <n <N), and passing the column of rank N to rank 1 (circular permutation).

The purpose of the tests was to first determine the optimum conditions for recovery of Li in the extract. Elution volumes were then increased until Li began to be lost in the raffinate. Material balances and concentration profile analyzes at the different stages of the treatment are carried out in order to follow the evolution of the position of the Li, Mg and S0 ₄ peaks. We then try to increase the productivity of the system by increasing the concentration of the feed or the speed of circulation of the brine in the columns if the pressure drops allow it.

Experience 1:

A strong cationic resin based on sulfonic groups is introduced at room temperature into a column after being stabilized by a 24 hour hold in 250 g / l NaCl brine to shrink. In simple elution tests with brine at 250 g / l NaCl, it was found that no contraction of the resin bed previously stabilized in this way was observed.

Simple elution tests through the resin thus prepared, introducing 20 ml of lithiated brine to 480 ml of resin and eluting with a brine of 250 g / l NaCl show that;

the first main compound to be predominantly removed from the column is sulphate;

the second main compound to emerge mainly from the column is Mg, accompanied by B;

the third main compound to be predominantly removed from the column is Li;

K leaves most of the column after Li.

It turns out that about 90% of the sulphate can be removed before the Li starts to come out of the column. This suggests that sulfate / Li separation is easy. On the other hand, only about 20% of the Mg was eliminated at the beginning of the Li output. It is therefore essentially on the Mg / Li separation that the optimization of the process must take place.

Experience 2:

Experiment 1 is resumed at 60 'Ό. It turns out that under these conditions 90% of the sulphate can be removed before lithium starts to come out significantly. About 50% of Mg has also been eliminated. In general, it turns out that the method according to the invention should preferably be implemented at a temperature of 10 to 80 ^<€, preferably between 20 and 60 ^<€, preferably between 40 and 60 ^<€.

Experience 3:

A synthetic lithiated brine representative of the composition of a brine resulting from a silver salar containing 70.8 g / l of Na, 4.16 g / l of Li and 21.4 g / l of Mg 85, is prepared. 8 g / l of S0 ₄ and 5.47 g / l of B.

A bed of resin A is prepared in a column whose resin bed has been compacted in 5 steps. In each step is introduced into the 1/5 column of the resin which will ultimately be present in the column, and is then circulated continuously in the column of deionized water at a rate of 20 ml / min for 1 h. Then a solution of NaCl at 300 g / l is continuously introduced into the resin at a rate of 10 ml / min for 2 h.

During the introduction of the lithiated brine, a flow rate of 10 ml / min is used until, at the outlet of the column, the concentrations of the principal elements equal to the concentrations are measured by means of sampling. at the column entrance, sign that the resin of said column has played its role during the corresponding step, and that it is time to move to the next step of implementation of the method.

The elution brine at 300 g / l NaCl crosses the columns at a rate of 10 ml / min for 2 h.

It was verified that the volume variation of the resin thus prepared, during the adsorption tests, was low, of the order of 2%, that the discharge rate of the materials was relatively constant during the tests, and that precipitation was not observed during the adsorption and elution steps.

These steps were conducted at room temperature with a volume of treated liquids of 2.3 BV / h, i.e. the volume introduced was equal to 2.3 times the value of the bed volume in each column ( BV) per hour. The reference BV is, in this case, the volume of the bed measured after its equilibration with the NaCl solution, therefore before any adsorption operation.

A study of the retention times for the various components taking as a reference the retention time of the sulphate during the adsorption leads to the following results, summarized in Table 2:

Adsorption Desorption Compound

Li 1, 8 1, 8

Mg 1, 3 1, 3 B 1, 1 1, 3

S0 ₄ 1, 0 1, 1

Table 2: retention times of the components of the brine in the resin

The separation properties of sulfate and Mg on the one hand and Li on the other hand are good for the resin A used.

Experience 4:

Tests were also carried out under the same conditions as for experiment 3 with a resin B, containing at least sulfonic groups, which differs from the previous one by the joint presence of acidic and basic groups. They also gave good results on the separation (sulfate + Mg) / Li, but a slower elution of Li than with the resin A. The latter is thus better adapted to an industrial use than the resin B. Experiment 5:

The lithiated brine was then treated at room temperature using the previously described SSMB device with six columns, one for zone 1, two for zone 2, two for zone 3 and one for zone 4. We will describe what happens in each area of the device ..

The strong cationic resin A based on sulfonic groups is introduced at room temperature into the six columns after having been stabilized by a 24 hour hold in 250 g / l NaCl brine to shrink.

The lithiated brine is introduced at the beginning of zone 3 (top of rank 4 column). This is where Mg / Li separation begins, the retention time of Li being greater than that of Mg. Li tends to remain in the upper parts of the columns while the lower parts of columns contain very much Mg. This makes it possible to bring out from zone 3 (bottom of the rank 5 column) a raffinate substantially free of Li and containing essentially Mg, S0 ₄ and B. This is achieved if the zone 3 is fed with a volume of liquid of order of 0.6 to 1.0 BV / cycle. A value of 0.9 BV / cycle can be recommended.

Zone 4 (row 6 column), as mentioned, is a buffer zone that pushes the solution avoiding mixing between the raffinate and the extract. For this, the volume of liquid supplying the zone 4 must be between 0.1 and 0.5 BV, for example 0.40 BV. As this zone comes after zone 3, it is essentially Mg ions that are accumulate in the upper part of the column, and it is a liquid whose composition is comparable to that of the eluent that emerges from zone 4 and is reinjected at the beginning of zone 1.

The eluent is introduced into zone 1 at the top of the rank 1 column, in order to push the extract, containing the Li, out of the column. For this, the quantity of liquid supplying the zone 1 must be greater than or equal to 1.0 BV in order to be able to evacuate at least 50% of the Li contained in zone 1.

Zone 2 is the area where the raffinate begins to form. The weakly retained elements are pushed while the other elements are retained. A volume of liquid between 0.5 and 1.0 BV circulates therein.

When a cycle is complete, the solution is pushed by eluent so that the zones can be shifted by one column and a new cycle can begin.

Claims

1. Process for the production of a lithium chloride solution from a lithiated brine, characterized in that the separation of the lithium chloride from the other components of the lithiated brine is carried out by means of an ion exchange resin arranged in at least one column (1, 2, 3, 4, 5, 6) and in that said separation is effected by means of a plurality of columns (1, 2, 3, 4, 5, 6) in a moving bed simulated (SMB).

2. The method of claim 1, characterized in that said separation is performed according to the simulated sequential moving bed method (SSMB).

3. Method according to claim 2, characterized in that an installation comprising N columns (1, 2, 3, 4, 5, 6) containing the resin with N≥ 4 is used, so as to allow the creation of four zones. in series in which circulates a brine, the exit of zone 4 being connected to the entry of zone 1, and in which:

for zone 2, the brine circulating in the plant is purified, by storing in a preferred manner the products with high affinity for the resin, preferentially LiCl, and by increasing the concentration of the brine in low affinity products for the resin, preferentially MgSO ₄ so as to form a raffinate, without adding or removing material;

for zone 4, the brine is circulated without adding or removing material.

4. Method according to claim 3, characterized in that at least one of said zones comprises a plurality of columns (2, 3; 4, 5).

5. Method according to claim 4, characterized in that the zone 1 and the zone 4 each comprise a column (1; 6), and in that the zone 2 and the zone 3 each comprise two columns (2, 3; , 5).

6. Method according to one of claims 3 to 5, characterized in that, for each cycle of treatment of the brine, one carries out as many steps as there are columns, namely:

^* A first sub-step is carried out where an injection of a volume of brine lithiated in the upper part of the first column of the third zone is recovered an equivalent volume of raffinate in the lower part of the last column of the third zone, a volume of elution brine is injected into the upper part of the first column of zone 1, the same volume of extract is recovered in the lower part of the last column of zone 1, and no do not circulate brine in zones 2 and 4;

a second substep where the first, second and third zones are then connected by isolating zone 4, injecting a volume of elution brine into the upper part of the first column of zone 1, and recovering a single raffinate volume in the lower part of the last column of zone 3;

7. Method according to one of claims 1 to 6, characterized in that the resin is a strongly acidic cationic resin having at least sulfonic groups and having a particle size of between 200 and 800 μηι.

8. Method according to one of claims 1 to 6, characterized in that the resin is a cationic resin containing at least sulfonic groups and together acidic and basic groups, and having a particle size between

200 and 800μηι.

9. Method according to one of claims 1 to 8, characterized in that:

10. Method according to one of claims 1 to 9, characterized in that the temperature at which it is performed is between 10 and 80 ° C, preferably between 20 and 60 ° C.

1 1. Process according to claim 3, characterized in that the elution brine has a dissolved solids concentration which differs by plus or minus 100 g / l from the dissolved solids concentration of the lithiated brine.

12. Method according to one of claims 1 to 1 1, characterized in that before the introduction of the lithiated brine, the resin has been stabilized by a residence in NaCl brine or a circulation of NaCl brine through the column or columns (1, 2, 3, 4, 5, 6).

13. The method of claim 12, characterized in that the volume of the resin bed (s) (BV) relative to which the amounts of brine are measured is the volume of the resin bed or beds after stabilization by said brine NaCl.