Process for improving the formation of hydrous alumina dispersed within a weak base anion exchange resin

PROCESS TO IMPROVE THE FORMATION OF DISPERSED HYDRATED ALUMINUM IN A WEAK BASED ANION EXCHANGE RESIN »

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The term weak base, as defined here, refers to anion exchange resins, in which the salt modalities of the amine functional groups are transformed into the OH modality by NH ^ OH.

The aforementioned patents describe anion exchange resins of the weak or strong base varieties, and disclose that the neutral halide salt modalities of the strong base resins can be used as starting substances. During the precipitation process of alumina hydrated in the resin by precipitation of ΑΙΟΙ ^ ammonia, the halide salt modalities of the weak base anion exchange resins are transformed into the CH modality. Anion exchange resins can have functional amine groups that are all essentially of the weak base variety, some that are all essentially of the strong base variety, and some that contain both varieties. This invention relates only to anion exchange resins, which contain which groups of the weakly based variance, this term having a weak base having the meaning previously attributed to it.

It has been found that the amount of aluminum in the hydrate, which can be incorporated into the resin by the precipitation of the ammonia from the Al halide, is limited, at any stage, by the maximum solubility of the Al halide and by the free volume in the resin. The ammonia treatment also transforms the weak base resin into the OH ”modality, which is only about 80 percent of the volume of the halide modality, and in this way, the volume available to absorb more halide solution becomes smaller. of Al.

It is, therefore, desirable to be able to introduce greater amounts of the aluminum halide into the resin.

The aforementioned shortcoming has been largely eliminated by the invention under consideration, which is a process for precipitating Al (OH) ^ in the reticles of a weakly based anion exchange resin by precipitating

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ammonia in the Al halide site itself, in an aqueous medium, thereby forming an anion exchange resin compound, having dispersed in it Al (OH) ^ compound which is characterized by:

(1) acidification of said compound, in an aqueous medium, with HX, in which X is chlorine, bromine, iodine or fluoride, in an amount sufficient to provide a pH of not less than about 5 °, thereby transforming the anion exchange resin in the halide salt modality.

(2) separating the compound from the aqueous portion;

(3) flooding the compound with a diluted Al halide solution, draining the excess solution; and (4) adding for the additional precipitation of Al (OH) na in the resin.

By the invention under consideration, the OH modality of the resin is transformed into the halide modality, without solubilizing the Al (OH) ^ in the resin. This allows additional amounts of Al halide to be absorbable and then transformed by treatment with ammonia into additional amounts of Al (OH). The preferred acid halide is HCl and the preferred Al halide is AlCl2.

treatment, with the acid halide, of Al (OH) ^, containing the resin OH ', must be done carefully, taking care that the addition of the acid is not so fast, than a drop concentrated in the pH, for o lower than 5, is reached. A slow addition of the acid is recommended, with stirring and carefully checking the pH. Any convenient process, for lowering the pH, by adding the acid halide, can be employed, since the process does not result in the solubilization of a considerable amount of Al (OH) ^ that is already in the resin.

The acid halide treatment phase is

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beneficially aided and accelerated by the addition of ammonium halide, especially NH4 Cl. The amount of NH ^Cl added may be greater than a reasonably wide range, with an aqueous dose of about 5% being particularly beneficial.^The 25 per cent NH 4 Cl. Other amine hydrochlorides can be used, but NH4 Cl is preferred. The ammonium halide acts as a buffer against concentrated super acidification during the addition of the acid halide, thereby allowing for a faster addition of the acid halide. The ammonium halide added initially, before the addition of the acid halide, can be removed, for the most part, when the resin is drained before the addition of more Al halide. Then, when NH ^ OH is added, to transform the Al halide into Α1 (ΟΞ) ^, more ammonium halide is formed.

HCl is the most suitable acid to use. However, if the hydrated alumina, Al (OH) ^, is to be converted into IiiC1.2Al (0H) j. However, if it is intended to transform into LiX.2Al (0H) ^, where X is a halogen other than chlorine, then it is recommended to use the corresponding acid halide and the corresponding ammonium halide, thus avoiding a mixture of halo compounds.

The temperature for use in treating with HCl or NH2 Cl / HCl should be in the range of about 20 ° C to about 100 ° C, preferably from about 45 ° C to about 100 ° C. If higher temperatures are to be employed in order to speed up treatment, superatmospheric pressures may be necessary to avoid considerable loss of ingredients through vaporization.

It appears that treatment with HCl or HH2 Cl / HCl swells the resin, thereby allowing subsequent phases of subsequent treatment, thereby providing appreciable increases in the aluminum content of the resin. Increases of three times or more in the content of the resin Al are readily achieved. Because of this increase in the Al content of the resin (first as hydrated alumina and then as LiX.2Al (0H) the compound has a greater capacity for re.

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cuperation of Li values⁺ pickles, and a more efficient process of recovering Li⁺. A higher load of aluminate in the resin allows a higher concentration of LiX in the effluent from the exchange column, when the Li is recovered⁺pickles.

We have also found that the formation of LiX.2Al (0Hjj crystalline, produced by heating LiX (in which X is Cl^- or OH) within the resin / Àl (OH) compound is increased when heating at a high pH, ​​for example about 11 to about 11.5, which is done in a metal container (other than glass) to avoid heating the highly alkaline mixture in the glass. The heating of highly alkaline mixtures in the glass can result in very small amounts of lithite silicate, which can interfere, to some extent, with the formation of highly crystalline LiX.2Al (OH).

The following examples illustrate the invention.

For comparison, the same resin was used in each of the following examples. This resin is a specific anion exchange and macroporous resin, comprising a cross-linked polymer of styrene-divinylbenz. in, having annexes tertiary amine groups.

EXAMPLE 1

A portion of the aforementioned resin is flooded with a concentrated aqueous solution of heat. aluminum straight is dried until it is flowing freely, and then it is treated with ammonium hydroxide, to cause precipitation of the aluminum hydroxide dispersed within the resin. The ammonium chloride, ammonium hydroxide and aluminum hydroxide are washed, leaving the resin in the OH mode containing the AL (OH) already dispersed therein. At this exact moment, the resin contains about 1.1 millimoles per cubic centimeter of Al per cubic centimeter of resin

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dry in the base mode.

The preparation of the resin in the drying mode is passed through the sieve, and 223.58 g of beads, mesh size of -30 are subsequently treated as follows: Add. Enough water is made to make a semi-liquid mixture, which is stirred from above with a mechanical blade paddle stirrer. About 40 g of NH4 Cl are stirred in the mixture; the temperature rises to about 80 to 95 ° θ, θ 75 ° meg of HCl is added slowly, during which the pH is not allowed to be below 5After having added all the acid, the pH remains at 5 »2. Production is 645 ml of resin. After the product has been thoroughly washed with water and drained dry to 460.3 g, a saturated solution of AlOl ^ (200 cc) is added to the resin, and then 20 g of water are added. an AlCly supplement After the exothermic phase begins to de. grow, the resin is filtered. The filtrate has a gravity s. 1.28. The resin product is dried in a flow of nitro, dry genius to a weight of 476.8 g. The dry substance is mixed in 380 cc of 30% NH2 OH and the resulting exothermic reaction is allowed to reduce. After stirring for half an hour, the solids are washed well by decanting the Al (OH) que which forms outside the resin. The washed resin is again mixed with water and heated. Again NH4 Cl and 720 meg of HCl are added, to again reach a slight acidity of not less than pH 5 · θ volume of the washed resin is 640 cc, after having dried at 507.5 g. Then, 250 cc of the saturated AlCl2 solution and 83 g of anhydrous AlCl2 are stirred with the resin, and then allowed to stand overnight.

The resin is filtered to a weight of 583.5 g and the wet-dry resin is mixed in 380 cc of 3% percent NH 3OH. After washing, the volume of the product is 580 cc.

Approximately 500 cc of the resin is added to an excess 35 percent AICl ^ solution, mixed and, in ί3, ο: δ.Ο, Οβ

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then filtered and dried in a stream of P³¹³4-46.8 g.

The dry resin is then mixed in 300 ml of 30 percent NH2 OH. After washing thoroughly to remove Al (OH) no outside, the volume of the resin is 450 ml. Each ml contains about 3.33 millimoles of Al.

Fifty grams of LiCl and saturated NaCl brine (lower Ca and Mg) are added to a volume of 750 ml and are heated to 68 ° C. The pH is 7.75 · After cooling for 20 hours, the mixture is heated to boil and add. 250 meg of NaOH are slowly added to a pH of 8.5 · The resin, a compound of LiX.2Al (0H) ^, is filtered and placed in a metal container at 95 ° C in the oven for 24 hours. Then, 40 g of NH4 Cl are added and heated, with stirring; as 722 meg of HCl is added to obtain the pH 5 at 90 ° C. The Al content is now about 3.1 millimoles per cubic centimeter of resin. The production is 470 cc of the resin compound.

A 118 cc sample of the resin is tested on a jacketed column and the temperature is controlled. A brine containing lithium from Arkansas is passed through it, at 20 cc per minute and at 90 ° C, until the effluent is the same as the influent, with respect to Li⁺, at 3.08 cc per minute and at 90 ° 0, and the effluent is collected. The first installment is 5θ cc; all others are 10.cc. The analysis with the flame photometer shows, in milligrams of Li per liter;

Installment 4 - 740)

- 5000 )

- 7650) 7 - 6800) 8 - 3266) 9 - 2450) (taking / 5, 6, 7, 0 average LiCl content is 3.97 percent, ie about 20 times the loading brine)

EXAMPLE 2

Following the process employed in Example 1, it was found that multiple precipitations of Al (OH) ^ in the resin

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anion exchange, prior to the reaction with LiOl to clear crystalline LiC1.2Al (0H), are more beneficial to obtain an increased dose of Li⁺ in the effluent of the li recovery process, than a single precipitation, as they are

<td>presented in the following are also</td><td>Mentioned patents the data:</td><td>on page 1. Introducing -</td>

<td>Precipitation</td><td>Loading Al</td><td>Cone, by Li⁺ in the effluent</td>

<td>of Al (OH),</td><td colspan="2">in resin (mmole Al / cc and Ilg Li * ”/ liter (oon-</td>

<td> 5</td><td>resin)</td><td>culminating)</td>

<td>only *</td><td>rvz 1.2</td><td> 3.000</td>

<td>multiple</td><td> 2,0</td><td> 4.000</td>

<td>multiple</td><td> 5,0</td><td> 5.200</td>

<td>multiple</td><td> 4,0</td><td> 6.200</td>

* For the purpose of comparison with previous Patents.