Mixed metal layered hydroxide-clay adducts as thickeners for water and other hydrophylic fluids.

DESCRIPTION

This invention concerns the thickening of water or hydrophilic solvents through the use of clay compounds and mixed metal stratified hydroxides.

There are various reasons for thickening water, aqueous solutions, hydrophilic solvents, and the like, such as for use as water-based metal work fluids, fire suppression (fire extinguishing) fluids, oilfield drilling fluids , food additives, hydroaulic fluids, water-based paints or coatings, separation and release solutions, and other applications in which the thickening of a liquid or a solution is beneficial.

Water thickening agents, such as guar gum and polyacrylamide, are not stable against high-shear hydrothermal treatment, at temperatures above about 121 ° C, oxidation, attack by bacteria, and salts. To compensate for and solve some of these problems, additives such as bactericides and antioxidants are sometimes required.

Thickening agents or viscosifying agents for aqueous materials, such as drilling fluids, which involve a certain form of hydrated aluminum compound, are described, for example, in US Patents 4,240,915; 4,349,443; 4,366,070; 4,389,319; 4,428,845; 4,431,550; 4,447,341; 4,473,479; and 4,486,318. Patents describing other forms of aluminum compounds for the same purpose are, for example, US 4,240,924; 4,353,804; 4,411,800; and 4,473,480. Similar patents, which describe other types of viscosifying agents, are, for example, US Patents 4,255,268; 4,264,455; 4,312,765;

4,363,736; and 4,474,667.

The above patents deal with the formation of hydrated aluminum compounds in situ. The main disadvantages of said process are: (1) The resulting thickened fluid contains copious amounts of reaction salts. This may be undesirable in many situations. For example, in applications such as paints, metalworking fluids, or water-based hydraulics, the presence of a salt could cause serious corrosion problems. In the case of oilfield drilling fluids, many performance enhancing additives do not work well if a salt was present. Therefore, it is desirable to drill in fresh water (again) if possible. (2) The reactions described in the cited patents are carried out in situ (for example, in the mud pit of a drilling tower). Under such conditions, the reaction cannot be adequately controlled and the properties of the resulting thickener may be unpredictable.

Other problems, which arise with the use of Al (OH) 3 as a gelling agent for procedures such as drilling fluids in oil fields, are the following:

one. It is known that Al (OH) 3 gels change harmfully over time, unless certain salts such as carbonate salts are present.

two. The rheology of Al (OH) 3 is not too constant with variable pH values. For example, a suspension of Al (OH) 3 can be very thick and uniform at pH 6, but at pH 10, which the drilling industry prefers, the suspension crumbles and Al (OH) 3 settles out of the suspension. . This creates significant problems, since most drilling operations are performed at pH values ​​within the range of 9 to 10.5.

A historically popular thickening agent, especially in a drilling mud, has been made of mineral clays, such as bentonite clay, often used together with other agents or densifiers, such as Fe2O3, BaSO4 and others. Variations from one batch to another batch of bentonite clay, and especially ion and temperature sensitivities have resulted in erratic results and adjustment of the formulation is often required during use; This hinders drilling operations.

Certain forms of crystalline stratified mixed metal hydroxides are described, for example, in US Patents 4,477,367; 4,446,201; and 4,392,979; in which the elements Li, Mg, Cu, Zn, Mn, Fe, Co and Ni form part of the stratified crystalline structure. Other metalolic aluminates are described, for example, in US Patents 2,395,931; 2,413,184; 3,300,577; and 3,567,472. These compounds are prepared by various reactions, including coprecipitations, intercalations, digestions with acids and digestions with bases.

In the drilling of oil wells, drilling fluids or “sludge” perform several functions:

one. Eliminate drilling debris from the well.

two. They cool the drill bit.

3. They provide hydrostatic pressure to equalize the pressure of the formation.

Four. They control the penetration of fluids into the formation and protect this formation.

Functions 1 and 3 in the above list can only be performed if there is an acceptable rheology in the drilling fluid. The most desirable rheology that a drilling fluid can exhibit is a pseudoplasticity. There are various shear zones in the borehole of a well and the fluid should have varying viscosities in these areas. In the ring or ring, between the drill pipe and the formation, the shear regime is approximately 100 to 1,000 sec^-1. In the drilling auger, the shear regime was between approximately 25,000 and 200,000 sec^-1 In the mud pit the shear regime is less than 30 sec^-1. In order to carry drilling solids with low shear rates, a fluid must have an important viscosity. However, if the fluid has a high viscosity next to the drilling auger, energy is lost when the fluid is pumped. Therefore, a good drilling fluid should be dilutable by shear. It is very important that the fluid maintains this rheology throughout the drilling process. However, many conditions

000 Unfavorable 457, which typically inhibit the performance performance of existing drilling fluids, are various cations such as calcium and magnesium, fluctuating concentrations of salts, high temperatures, oxidation conditions and the presence of bacteria.

Some of the commercially accepted gelling agents, which are used in water-based drilling fluids, are polymers such as xanthan gum, guar gum and polyacrylamides. Non-polymeric gelling agents are, topically, clays such as bentonite and attapulgite. Each of these gelling agents has its own limitations. The polymers have topically instability against various salts, are susceptible to oxidation and attack by bacteria, degrade under extensive shear, and are only thermally stable at temperatures of around 120 to 150 ^ C. The clay type gelling agent, the most popular, is bentonite. Bentonite is severely affected by polyvalent cations and is limited to about 93 C unless certain diluents are incorporated. However, bentonite cannot be oxidized, and is completely stable against high shear conditions.

Frequently, polymeric materials are added to the bentonite dispersions in order to be able to use less clay. Some of the common bentonite extenders are polyacrylamide, and the copolymer Benex^(R) , which was available from Baroid. In a topical extended bentonite system, the level of bentonite was between 42.75 and 57 kg / m³, and the level of extender polymer was usually between 0.285 and 1.425 kg / m³. The extended bentonite system is still susceptible to experiencing problems associated with divalent ions such as Ca⁺², and is only as thermally stable as the extender polymer. The systems are also susceptible to attack by bacteria and oxidation.

In accordance with the present invention, a new composition of matter is prepared, consisting of the reaction product of at least one mineral clay, such as sodium bentonite, and a stratified mixed metal hydroxide. This new composition has utility as a gelling agent of, for example, a perforation fluid, or other thixotropic fluid. The mixed metal stratified hydroxide compound has the following empirical formula

LimDdT (OH) (m + 2d + 3 + na) A_toⁿ.qH2O (I) in which:

D represents divalent metal ions; d is the number of ions of D, from zero to about 4;

T represents trivalent metal ions;

A represents monovalent or polyvalent anions, other than OH^-;

m is from about zero to about 1;

to the ionic isomer of A;

n is the valence of A;

na is from zero to about -3;

(m + d) is greater than zero;

q is from zero to about 6; and (m + 2d + 3 + na) is equal to or greater than 3.

These mixed metal stratified hydroxides are preferably prepared by an instantaneous coprecipitation (of the "flash" English), in which soluble compounds, for example salts, of the metals, are mixed intimately (using stirring or mixing without shearing) with an alkaline material that It supplies hydroxyl groups to form the crystals of mixed metal hydrated oxides. While the empirical formula is similar to that of compositions described above, a distinctive feature of the present composition is that the crystals are essentially of the monolayer type, or a mixed metal hydroxide layer per unit cell. In a liquid vehicle, the essentially "monodispersed" staion crystals mean that individual crystals are distinct layers of mixed metal hydroxide. These monolayers, monodispersed crystals, are considered new.

In the previous formula (I), m can be from zero to about 1, more preferably 0.5 to 0.75, when used.

The metal D represents divalent metabolic ions and can be Mg, Ca, Ba, Sr, Mn, Fe, Co, Ni, Cu, Zn, most preferably Mg ooCa, omezules thereof, and the value of d can be from zero to about 4, preferably 1 to 3 and most preferably about 1.

The metal T may be Al, Ga, Cr o Fe, preferably Al oFFe, and preferably Al.

The anions A can be monovalent, divalent, trivalent or polyvalent, and they can be inorganic ions, such as halide, sulfate, nitrate, phosphate or carbonate ions, preferably halide halide, sulfate, phosphate or carbonate, or they can be hydrophilic organic ions such as glycolate, lignosulfonate, polycarboxylate, polyacrylates, or salts thereof, such as sodium polyacrylate. These anions are often the same as the anions that are part of the precursors of the metabolic compounds from which these new crystals are formed.

The formula compound (1) and its clay adduct are both substantially balanced and are preferably neutral in charge. The expression "substantially balanced" means that there is little positive or negative net charge.

The liquid that is gelled by the new mixed metal hydroxides, which are described herein, may be an aqueous liquid, such as water or an aqueous solution, or a hydrophilic organic material such as an alcohol or a ketone; also in a dispersion or emulsion, which comprises an aqueous medium containing non-soluble ingredients (either organic or inorganic) in dispersed form, it can be gelled by using the gelling agent presently described. While the present gelling agent has been found useful as a thickening agent for metal-based, water-based fluids, fire extinguishing fluids, food additives, hydroaulic fluids, lóatex type paints, separation and release fluids , lubricants, and others, especially where

000 457 extreme pseudoplasticity is a desirable property, which is especially useful in drilling fluids, whether for drilling oil wells, water wells or gas wells, including drilling at the bottom of the ocean.

A mixture of the selected, soluble metal compounds, especially the salts of airborne (for example, chlorides, nitrates, sulfates, phosphates) are dissolved in an aqueous vehicle. The ratios of the metal ions in the solution are predetermined to give the desired ratios in the final product. The concentration limit of the metal compounds in the solution is governed, in part, by the saturation concentration of the least soluble metal compounds in the solution; any undissolved portion of the metal compounds can remain in the final product as a separate phase, which is not usually a serious problem, if the concentration of said separated phase is a relatively small magnitude compared to the soluble portions, and preferably It is not more than about 20 percent of the amount of soluble portions. Then the solution is quickly and intimately mixed with an alkaline source of OH ions^- while shear agitation is substantially avoided, thereby forming monodispersed crystals of mixed metal layered hydroxides. A convenient way to achieve said mixing is to circulate the various feed streams within a mixing tea, from which the mixture circulates, leading to the reaction product, including the stratified hydroxides of monodispersed mixed metals of formula (I) above. . Then, the mixture can be filtered, washed with fresh water to remove soluble foreign ions (such as Na ions⁺, NH₄⁺, and other soluble ions) that are not part of the desired product.

The particular electromagnetic transmission microscope, which is used to perform crystallographic analyzes of the stratified mixed metal target hydroxides, was operated together with its maximum detection limits, this is a resolution of approximately 8 angstroms. The monodispersed crystals were so thin, in relation to their diameter, that a certain curl of the monolayers was found, making exact measurements of the thickness difficult, but reasonable estimates placed the thickness of the crystals within the range of 8 to 16 angstroms for various crystals During the drying process, a certain agglomeration of the crystals is evident in the analysis, giving rise to particles containing a plurality of the monolayer unit cell structures. Many non-agglomerated, flattened crystals are detectable in the analysis. These monolayer crystals are in contrast to the 2-layer and 3-layer unit cell structures, which are mentioned in US Patent 4,461,714.

A process for preparing the mixed metal layered hydroxide composition, but which is not exclusively the only process, is to react a solution of metal salts, such as magnesium and aluminum salts (approximately 0.25 molar) with an appropriate base such as ammonia or seodic hydroxide in amounts sufficient to precipitate the stratified hydroxide compound of mixed metals of the starch (I). For amoene hydroxide, the most preferable range is between 1 and 1.5 equivalents of OH^- per year equivalent.

Precipitation should be done with little or no shear, so that the resulting florets or flakes are not destroyed. One method of achieving this is to circulate two currents, the salt current and the base current, towards each other, in such a way that they affect an area of ​​convergence, of low shear, as would be found in a tea. The reaction product is then filtered and washed, producing a filter cake with approximately 10 percent of seolides. At this point, if the mixed metal stratified hydroxide composition has been carefully washed to reduce the concentration of dissolved salts to a relatively low point, for example 300 ppm or less, a singular and strange phenomenon occurs. For a certain period of time, the filter cake goes from being a seolite waxy material to becoming an opalescent liquid, which effectively disperses light. If ionic material is added back to the dispersion, the viscosity increases dramatically and the dispersion gels. The "relaxation" regimen is dependent on the concentrations of free ions in the dispersion and will not occur if the concentrations are too high. The effect of various ions on the relaxation process differs. For example, the relaxation process is more tolerant for monovalent ions, such as chloride ions, than for polyvalent ions, such as sulfate, carbonate or phosphate.

If the relaxed dispersion is dried, when the level of seolides reaches approximately 20 to 25 percent, the material forms a translucent, hard and solid material, which is very fragile. This can be crushed to form a powder, even if it has a concentration of approximately 80 percent water. This solids will not be redispersed in water or other hydrophilic solvents. Even if shear is applied with a Waring Blender mixer or an ultrasonic cell breaker, seolides cannot be made to form stable dispersions.

A fruitful method of drying the material consists in adding a certain amount of hydrophilic organogenic material such as glycerol or polyglycol to the relaxed dispersion, before drying. If this is done, the resulting dry material will spontaneously disperse in water. If a salt is then added to this dispersion, the fluid will accumulate viscosity in the same manner as the liquid dispersion. This drying technique is ineffective if significant quantities of dissolved salts are present in the dispersion. In this case, a certain amount of dispersion is possible, but the resulting fluid would not accumulate viscosity.

One of the distinguishing characteristics of hydrated mixed metal oxides, which are described in the present case, is that, after filtration, after instantaneous coprecipitation, a gel is left on the filter that is predominantly labile with hydrated oxides.

000 457 crystals swollen by the liquid so that those are not visible as a solid phase. The gel can be referred to as a "semi-solution" or "quasi-solution" and it looks and feels like a semi-solid wax. This was in contrast to the precipitates of hydrated oxides of the prior art, which are easily separated by filtration from a liquid, in the form of solid material as discrete particles. Apparently, the particular crystalline morphology, obtained here, allows or causes the embedding and retention of large amounts of liquid.

The mixed metal hydroxide can also be composed of pure mixed metal hydroxy compounds or physical mixtures of the stratified compounds with themselves or with other hydrated oxides of the D or T metals, such as hydrated alumina, hydrated magnesia, hydrated iron oxides , hydrated zinc oxide, and hydrated chromium oxides.

Although this specification is based largely on the forms of so-called bentonite clays, it should be noted that other forms and classes of clay, such as amorphous clay (for example of the aliphane group) and crystalline clay, are within the scope of the present invention. (for example 2 layers, 3 layers, the expandable type, the non-expandable type, the elongated type, the regular mixed layer type, and the chain structure type). For example, a non-exhaustive enumeration of clays is as follows:

bentonite kaolinite haloisite smectite montmorillonite vermiculite chlorite atapulgite sepiolite paligorsquita illita bacon earth saconite.

If certain amounts of the compound mixed stratified hydrochloride hydrochloride compound (I) are mixed with an aqueous dispersion of sodium bentonite, which has a concentration as low as 0.5 percent by weight, the viscosity of the resulting dispersion will increase dramatically . The elastic point or limit increases dramatically and the plastic viscosity increases only slightly. The lower margin of the synthetic bentonite can be approximately 5.7 kg / m³(0.6 percent by weight), and the minimum amount of stratified mixed metal hydroxide, which is required to accumulate a significant viscosity, is approximately 0.285 kg / m³ (0.029 percent by weight). The benefits observed are that the resulting suspension of clay and mixed metal stratified hydroxide is not essentially affected by varying calcium concentrations; this appears as being thermally stable at least 204 C (test for 16 hours), effectively supports densifying materials such as barite; it is compatible with common fluid loss control agents such as carboxymethyl cellulose, carboxy ethyl cellulose, and polyacrylates; and the viscosity, especially the elliptical point, can be easily controlled with commercial diluents such as lignite and lignosulfonate.

The interaction with bentonite of the mixed metal stratified hydroxide appears as implying an ion exchange phenoimine. Our theory regarding interaction is as follows. It is normally known that clays, such as bentonite, have structural defects that give rise to net negative charges on the clay crystals. These charges must be balanced by cations in order to achieve electrical neutrality, resulting in the capacity for cation exchange observed with bentonite. In the case of sodium bentonite, which is usually the clay chosen for drilling fluids, sodium ion balances the charge on the glass. Our data also indicates that there is a significant amount of anion exchange capacity in the mixed metal stratified hydroxy compounds, which are described herein. We believe that mixed metal stratified hydroxide interacted with bentonite by exchanging ions with sodium ions. The result of this reaction is that there is an increase in the concentration of soluble sodium salts in the dispersion. Sodium comes from clay and anioin comes from stratified mixed metal hydroxide. Since the reaction seems to be an ion exchange reaction, it should be possible to prevent it from being carried out, or destroy the interaction of clay and mixed metal stratified hydroxide, replacing in the system with an ion or a group of ions having an affinity for the clay or for the mixed metal stratified hydroxide compound, greater than the respective associated crystal. Said ion is the phosphate ion. If phosphate ions are present in the mixed metal stratified hydroxide compound, interaction with the clay is not performed. If phosphate ions are added to a dispersion containing bentonite and mixed metal stratified hydroxy compounds, the viscosity decreases and the interaction can be completely destroyed. Other ions that can give rise to the same effect are organic ions such as lignite, lignosulfonate, and the like. Some ions that do not significantly decrease viscosities are Na⁺, Ca⁺², Mg⁺², Cl^-, CO3^-2, HSySO4^-2. This is not intended to be a complete list of ions that do not interfere with the interaction, but is only given as a means of showing the type of ions that may be compatible with the system.

Since a chemical reaction occurs between clay and mixed metal stratified hydroxy compounds, we believe that a new composition of matter has been formed. It seems that this new composition is a salt in which the cationin is a stratified hydroxide crystal of mixed metials and the anioin is a clay radical or radical. The composition is characterized as a compound in which both the cation and the anioin are discrete crystals. The compositions could be referred to as a "crystal salt," or it could be said that, in aqueous dispersion, pairs of crystal ions exist. This assumption is further supported and substantiated by the fact that it is revealed

000 457 that the degrees of interaction are associated with the exchange capacity of available cations of the clay that was being used.

The salt or crystal adduct can be prepared by reacting, by intimate mixing, an aqueous gel or an aqueous dispersion of the stratified hydroxide with an aqueous dispersion of the clay, whereby metalic ions from clay and anions from stratified hydroxide pass into the aqueous solution by ionic exchange of clay anions with stratified hydroxide anions and thereby form an adduct of the stratified mixed metal hydroxide and clay.

The adduct formed preferably has a weight ratio of stratified hydroxide / clay from about 0.02 / 1 to about 1/1.

In each of the subsequent examples, the mixed metal stratified hydroxide compound was prepared by coprecipitation. Then these were filtered and washed to produce pure material. This purified product was then dispersed in water containing certain amounts of clay minerals to form the thickened fluid.

The following examples are given to illustrate certain embodiments, but the invention was not limited to the particular embodiments shown.

Example 1

A 0.25 molar solution of MgCl2 was prepared. .AlCl3. Then this solution was pumped through a peristotic pump into an arm of a tea. A 2.5 molar solution of NH4OH was pumped into a second opposite arm of the tea, so that the two solutions converged in the tea. The product spilled out of the third arm and into a broad mouth glass (called precipitates). The flow rates of the two solutions were carefully adjusted so that the product of the coprecipitation reaction had a pH of approximately 9.5. In this situation, this amounts to an excess of NH4OH of approximately 10 to 20 percent. The reactor product consisted of delicate flakes or flocculates of MgAl (OH) 4.7Cl0.3 suspended in an aqueous NH4Cl solution. Then, the dispersion was carefully poured into a Buchner funnel with an intermediate paper filter. The product was filtered and washed inside the filter with water to remove excess NH4Cl. Cl concentration^- dissolved was approximately 300 ppm, measured by a specific ionic electrode for Cl^-. The filter cake that resulted was translucent, but not optically transparent.

The cake had a concentration of approximately 9 percent solids by weight, determined by drying a sample at 150 C for 16 hours. The cake had the consistency of soft candle wax. The product was analyzed for MgyAl. The Mg: Al ratio was found to be essentially 1: 1.

Electronic micrograph analysis of the product revealed tiny inserts with diameters of approximately 300 to approximately 500 angstroms. The particles were so thin that, in some cases, they curled up. The thickness estimates of these crystals are from about 10 to about 20 angstroms. The maximum resolution of the microscope is approximately 8 angstroms.

The theoretical thickness of a MgAl (OH) layer 4.7 Cl0.3 is 7.5 angstroms. It should also be noted that in the process of preparing the sample for electron microscopy, the material was dried, which probably caused a certain degree of agglomeration, giving rise to particles containing a plurality of single-layer unit cell structures.

After settling undisturbed for approximately 16 hours, the filter cake had the consistency of petroleum jelly. After about 48 hours, the material was a thixotropic liquid. The relaxation process continued for approximately 5 days. At the end of this period of time, the product was more viscous than water, but was pourable.

A progenitor dispersion containing 57 kg / m was prepared³ of sodium bentonite (obtained from Baroid under the brand name Aquagel) and allowed to settle without disturbances for 24 hours. Then several dispersions were prepared from the progenitor dispersion. Each contained 14.25 kg / m³ of bentonite and the amount of MgAl (OH) 4.7Cl0.3, described above, was varied from 0.285 kg / m³ at 2.85 kg / m³. The following Table I lists the point or elastic limit, the plastic viscosity and the mecoan gel strengths at 10 seconds and 10 minutes for each of the compositions, measured using a Fann viscometer.

TABLE I

<td>TO</td><td>B</td><td>C</td><td>D</td><td>AND</td>

<td> 0,285</td><td> -2,44</td><td> 2,0</td><td> 0,00</td><td> 0,00</td>

<td> 0,855</td><td> 14,64</td><td> 3,0</td><td> 1,22</td><td> 4,88</td>

<td> 1,425</td><td> 51,24</td><td> 3,0</td><td> 19,52</td><td> 24,40</td>

<td> 2,28</td><td> 119,56</td><td> 4,5</td><td> 46,36</td><td> 39,04</td>

<td> 2,85</td><td> 136,64</td><td> 6,5</td><td> 39,04</td><td> 34,16</td>

Being:

A Amount of mixed metal hydroxide, added to the dispersion of bentonite, in kg / m³

B Elóastico point in kg / 100 m²

C Plastic viscosity cp.

D Gel resistances in kg / 100 m² gel 10 sec.

E Gel resistances in kg / 100 m² gel 10 min. Example 2

A sample of ultra pure sodium bentonite (obtained from Baroid, under the brand name Aquagel Gold Seal) was dispersed in deionized water to give a dispersion of 28.5 kg / m³. This was allowed to settle for 24 hours. Two 350 ml allochthotic portions of the bentonite suspension were prepared. One of them did not contain MgAl (OH) 4.7Cl0.3 and the other containing 2.85 kg / m³of MgAl (OH) 4.7Cl0.3 described above. It was also prepared in a 350 ml sample, which only contained 2.85 kg / m³ MgAl (OH) 4.7 Cl0.3 ynadadebentonite. Next, each of the samples

000 457 was filtered in an API press filter at 7 kg / cm².

The filtrates were placed in polypropylene bottles washed with an acid. A sample of MgAl (OH) 4.7Cl0.3 and deionized water, which was used throughout the experiment, was filtered through the filter press. After the filtrates had been collected, the solutions were analyzed for 27 elements with a Leeman Plasma Spectrometer. The elements that appeared in significant quantities were Na, Ca and Mg. The chloride is analyzed by means of a specific ionic electrode and the NH₄⁺ It will be analyzed colorimetrically. The results are tabulated below in Table II. TABLE II

Concentration, meq / 1

<td>_*</td><td>NH₄⁺</td><td>Na⁺</td><td>_Mg⁺²</td><td>Ca + 2</td><td>Cl^-</td>

<td>TO</td><td> 0,04</td><td> 0,012</td><td> 0,014</td><td> 0,01</td><td> 0,28</td>

<td>B</td><td> 2,79</td><td> 0,00</td><td> 2,24</td><td> 0,08</td><td> 3,09</td>

<td>C</td><td> 1,16</td><td> 6,17</td><td> 0,08</td><td> 0,08</td><td> 5,49</td>

<td>D</td><td> 1,63</td><td> 0,0</td><td> 2,16</td><td> 0,00</td><td> 0,00</td>

Being:

* - Composition of the sample

A - H₂Or deionized

B - 2.85 kg / m³ MgAl (OH) 4.7Cl0.3

C - 2.85 kg / m³ MgAl3 (OH) 4.7Cl0.3 and 14.25 kg / m³ of sodium bentonite D - No. of meq. of ions exchanged in bentonite

From the foregoing, the following calculations are made:

meq of Na⁺ in excess = / Na / - / NH4 / - / Mg / = 6.17-1.63-2.16 = 2.38.

N^° from meq. of Cl ions^- exchanged from MgAl (OH) 4.7 Cl0.3 = 5.49-3.09 = 2.40 meq.

These data indicate that substantially equivalent amounts of sodium and chloride ions are released when the reaction is performed.

It will be understood by the practicing technicians of these relevant sectors, that the adducts formed in accordance with the present invention will be expected to have "hydration waters" that accompany them, unless they are expelled by an elevated temperature, generally greater than approximately 100^°C. Therefore, in formula (I) and in its adducts with clay, qH2 is hydration water where q is zero to about 6.

000 457