WO1991015429A1

WO1991015429A1 - Process for producing swellable laminated silicates

Info

Publication number: WO1991015429A1
Application number: PCT/EP1991/000586
Authority: WO
Inventors: Britta Liesenfeld; Hans Dolhaine; Heinz Müller; Claus-Peter Herold; Stephan Von Tapavicza; Willi WÜST; Josef Wollmann
Original assignee: Henkel Kommanditgesellschaft Auf Aktien
Priority date: 1990-04-04
Filing date: 1991-03-26
Publication date: 1991-10-17
Also published as: DE4010878A1

Abstract

The invention relates to a simplified process for producing swellable smectite-type laminated silicates by hydrothermal pressure treatment of mixtures and/or coprecipitates of the laminated silicate-forming components in the presence of excess water and free bases. The new process is characterized in that a reaction mixture containing excess base in the form of ammonia is introduced into the hydrothermal reaction step, and in that during processing of the reaction raw product, the aqueous-basic reaction medium is at least partially separated from the laminated silicate formed, if so desired.

Description

Process for the production of swellable layered silicates.

The invention relates to a simplified synthesis process for the production of water-swellable smectite clays and describes in particular a possibility in a simple manner to master the difficulties which arise in the production of highly swellable hectorites, saponites and / or saponite-hectorite hybrids.

The synthesis of phyllosilicates, especially hectorites, has been widely described in the literature (H. Strese and U. Hoffmann, Z. Anorg. Allg. Chem. 247 (1941) 65-95; WI Grandquist and SS Pollack in "Clays and Clay Minerals "Natl. Acad. Sei., Natl. Res. Council Publ. 8 (1960) 150-169; DE-AS 1 667 502). A recent literature entry deals in detail with the knowledge available today on the structure, genesis and production of hectorite, cf. Karl-Heinz Bergk et al. Chem. Techn. 41 vol., Issue 6, 245-251.

Highly swellable layered silicates of the smectite type (in particular hectorite, saponite and / or saponite-hectorite hybrids) are widely used, for. B. in the fields of cosmetics, paints, paints, wastewater treatment and rinsing liquids. In almost all applications, the pronounced swelling capacity of the representatives of this class of compounds in water is used. The use of naturally occurring materials of the type concerned here often stands in the way of their limited purity, so that the synthesis of corresponding materials with predeterminable material properties is of great importance. In practice, hydrothermal synthesis at high temperatures of of paramount importance. Details of the synthesis can be found in particular in the last-mentioned literature reference Karl-Heinz Bergk et al. , see . here in particular the flow diagrams from Figures 3 and 4 on page 247 aa. O.

A large-scale application area of high swellable synthetic layered silicates of the type concerned here is. the use thereof as a viscosity-building agent in aqueous drilling mud and borehole treatment agents in the exploration and development of deposits of, for example, petroleum and natural gas, but also in Ceothermal drilling, water drilling, in the execution of geoscientific drilling and in drilling in the mining sector. From the relevant literature, EP-A 260 538 should be mentioned here in particular. The use of selected synthetic swellable sheet silicates of the hectorite and / or saponite type for such water-based drilling fluid systems is described here. The last-mentioned literature reference describes in Example 1 a typical process for the production of the synthetic layer silicates of the hectorite type to be used there. An aqueous suspension is prepared from magnesium sulfate, sodium hydroxide solution, sodium silicate solution and lithium carbonate and is then reacted for about 4 hours at 180 ° C. in a stirred autoclave. The resulting product must then be filtered off from the mother liquor and the filter cake thus obtained must be washed with deionized water before the material is dried. These decisive steps of filtering a primarily formed hectorite slurry with subsequent washing of the separated solid phase are also integral components of the flow diagrams 3 and 4 from the cited literature reference Karl-Heinz Bergk et al. op. page 247 method shown. This filtering and washing is necessary to remove foreign constituents which have been introduced into the crude reaction mixture via the reactants and / or reaction auxiliaries used are. As a rule, these are water-soluble salts such as sodium sulfate, sodium carbonate or sodium chloride and the excess of free alkali used in the hydrothermal synthesis.

This apparently simple step of separating off the aqueous phase containing dissolved salts and then washing the synthetic smectite clay poses considerable difficulties for the practical process. This is immediately understandable from the following: The highly swellable layered silicate stubbornly holds onto at least parts of the aqueous reaction phase and requires special intensity for the subsequent cleaning with a water wash. The economy of the overall process is unduly burdened by the processing steps mentioned here. This is where the object of the invention begins.

The invention has set itself the task of designing the known process for the production of synthetic and, in particular, highly swellable smectite clays in such a way that cleaning the crude reaction product by filtration and subsequent washing no longer poses the previously known difficulties. In a special embodiment, the invention aims to make it possible to obtain high-purity smectite clays of a given structure and swellability by simply drying up the reaction crude product which is primarily obtained in the hydrothermal reaction, without intensive washing of the reaction raw product being necessary.

To achieve this object technically, the invention provides two main elements: the formation of the basic environment for the hydrothermal conversion is ensured by the use of a selected volatile base. In a preferred embodiment, the reactant mixture for the hydrothermal layered silicate-forming reaction should also be free or practical be free from those constituents that form non-volatile reaction by-products, in particular corresponding salts, during the implementation.

The invention accordingly relates to a process for the production of swellable layered silicates of the smectite type by hydrothermal pressure treatment of mixtures and / or coprecipitates of the layered silicate-forming components in the presence of an excess of water and free bases. The new process is characterized in that a reaction mixture is introduced into the hydrothermal reaction stage, the base excess of which is formed by means of ammonia. When processing the crude reaction product, if desired, the aqueous-basic reaction medium is at least partially separated from the layered silicate formed.

In an important embodiment, reaction mixtures containing at least predominantly oxidic and / or hydroxide reactants are used as the starting material for the hydrothermal reaction. These feed mixtures are essentially free of non-volatile foreign constituents and contain, as volatile mixture components, the water required for hydrothermal synthesis and ammonia for setting the basic reaction medium.

The process according to the invention is of particular importance for the production of synthetic swellable layered silicates as described in EP-A 260 538 and are accordingly characterized by the following general formula (1)

MgO. aMA. bAI ₂ O ₃ . cSi0 ₂ . nH ₂ 0 (I)

in the mean M = Na and / or Li with a Na / Li ratio equal to or greater than 1

A = F ^~ , OH ^~ and / or 1/2 O as well as a, b, c and n numbers are according to a = 0, 1 to 0, 6 b = 0 to 0, 3 c = 1, 2 to 1, 7 n = 0 to 3.0.

In the approach for hydrothermal synthesis, in the preferred embodiment described above, the reactants containing magnesium, aluminum and silicon are introduced as oxidic and / or hydroxide reaction components. The same applies to sodium and possibly lithium, unless the fluoride ion has to be introduced here. Mixed compounds, such as sodium silicate and / or sodium aluminate, can be added to the reaction mixture in a manner known per se. It is essential for the invention that the use of disruptive amounts of foreign constituents, such as are entered into the reaction mixture, for example when magnesium salts are used - for example of the type of magnesium sulfate or magnesium chloride - and thus the need for subsequent separation and Request cleaning of the raw reaction product.

After the hydrothermal reaction phase has ended, the swellable layered silicates formed can be freed from water and ammonia simply by drying. This drying can be carried out at normal pressure and / or at reduced pressure and can be accelerated by using elevated temperatures. The portions of the reaction mixture which are driven off via the vapor phase can, if desired, be condensed and used in whole or in part in circulation for further reaction mixtures. The drying of the product and / or that The free volatile base can be stripped off, for example, at temperatures up to 300 ° C., preferably in the range between 50 and approximately 250 ° C., the temperature range from approximately 80 to 180 ° C. being particularly important.

With this drying stage, not only the water but in particular also the volatile basic compound used for the reaction control can be driven off in the process according to the invention. This process step can be carried out in one or more stages in the sense of a joint removal of water and volatile base or a gradual separation of these volatile reaction aids.

The time period for such a final drying and / or temperature treatment results primarily from the time period required for the volatile components to be driven off. In general, this period will not exceed 1 to 2 hours. The temperature treatment can range from a few minutes to about 45 minutes.

The solid reaction product obtained is expediently ground into a fine powder. All suitable grinding devices, for example toothed disk mills, are suitable for this.

In order to carry out the basic reaction under the conditions of the hydrothermal synthesis in detail, the extensive details of the referenced prior art apply. Thus, in the preferred embodiment, magnesium hydroxide or magnesium oxide can be used as the magnesium-containing compound; in particular, amorphous silicic acid, for example precipitated silica, diatomaceous earth, but also water glass can be used as the silicon-containing compound, with the proviso that the sodium hydroxide content which is registered at the same time is the stoichiometric desired proportion not or not significantly exceeds. Aluminum hydroxide, so-called aluminum moist hydrate or aluminate lye can be used as the aluminum-containing compound, taking into account the restriction given previously for water glass. A suitable lithium-containing compound is, for example, lithium hydroxide. If fluoride ions are to be introduced into the reaction product, appropriate proportions of sodium and / or lithium fluoride are particularly suitable.

The amount of volatile base to be used in each case can be in a relatively wide range and - based on the magnesium oxide present in the reaction mixture - can be, for example, in the range from 0.1 to 5 mol of the volatile base per mol of magnesium oxide. It will generally be preferred to limit the amount of this basic component as much as possible so that preferred addition amounts of the base to the reaction mixture for the hydrothermal reaction are in the range of about 0.2 to 2 moles of ammonia per mole of magnesium oxide in the reaction mixture.

The information given in the prior art also applies to the choice of the process parameters of the hydrothermal reaction. Accordingly, the reaction is carried out in particular under the pressure of the reaction mixture at process temperature. The process temperatures in particular range from about 150 to 300 ° C., expediently from about 200 to 270 ° C. The reaction time is in the range of 1 to 100 hours, preferably between about 1 and 20 hours. After about 2 to 8 hours, the reaction has usually progressed so far that the workup can be carried out in the sense of the drying treatment according to the invention.

The solids contents during the hydrothermal reaction phase are in the usual range. For example, the solids content can be up to about 40% (by mass) in aqueous / basic Reaction mixture can be raised. However, preference is given to working at lower solids contents, which are in the range up to approximately 15% (mass fraction) and in particular below approximately 10% (mass fraction). In detail cf. the details of the cited prior art document, for example in Karl-Heinz Bergk et al. ok

In further refinements, the invention relates to the swellable smectite clays produced by the process according to the invention and to their use in particular in the context of water-based drilling fluid systems, as described in detail in EP-A 260 538.

B e i s p i e l e

■ Example 1

To carry out the hydrothermal synthesis in a reaction autoclave, the reactants given below are combined:

21.0 g MgO, 98% 2.0 g LiOH, 98 ig

79.1 g water glass 37/40 (HENKEL)

26.4 g precipitated silica FK320 (DEGUSSA) 13.6 g ammonia solution, 25% 863.8 g dist. water

The mixture of reactants in this batch corresponds to the following molar ratios:

1 MgO: 1.5 Si0 ₂ : 0.08 i ₂ 0: 0.2 Na ₂ 0: 0.4 NH: 120 HO

The details are as follows:

Magnesium oxide was slurried in about 700 g of water on a Pendraulik stirrer, lithium hydroxide was dissolved in it, and the mixture of water glass, about 150 g of water and precipitated silica was added. After stirring for 5 minutes, the suspension was added to the autoclave, to which the ammonia solution was added after sealing. Crystallization: 4 hours at 250 ° C

After cooling, the product thus produced was immediately dried in a forced-air drying cabinet at 120 ° C. and ground. Example 2

According to the ^information of Example 1, a series Reaktions¬ is batches with the respective following molar ratios compiled zu¬:

1) Hectorite a) 1 MgO: 1.5 Si0 ₂ : 0.08 Li ₂ 0: 0.2 Na ₂ 0: 0.4 NH ₃ : 120 H ₂ 0 b) 1 MgO: 1.5 Si0 ₂ : 0 , 08 Li _∑ 0: 0.1 Na ₂ 0: 0.6 NH ₃ : 120 HO c) 1 MgO: 1.5 Si0 ₂ : 0.08 Li ₂ 0: 0.1 Na ₂ 0: 1.2 NH ₃ : 120 H ₂ 0

2) Saponite a) 1 MgO: 1.15 SiO ₂ : 0.03 Al ₂ 0 ₃ : 0.35 Na., 0: 1.0 NH ₃ : 120 H ₂ 0

The respective products were examined according to the following main criteria:

X-ray diffraction analysis (crystallinity)

Viscosity of the 2.5% suspension in distilled water after 24 hours

Modified sedimentation number (swelling capacity)

The procedure for determining the modified sedimentation number is as follows:

2 g of the reaction product in 94 ml of 0.01 molar aqueous EDTA solution are stirred for 8 minutes, then 4 ml of a 1 oily sodium chloride solution are added and the mixture is stirred for 2 minutes. The product is placed in a measuring cylinder. After 24 hours in the measuring cylinder at room temperature, the volume ratio of sediment / total volume is determined. The working conditions used in the respective tests are given in the table below. Basically, all products produced show a well-defined crystalline structure in X-ray diffraction analysis.

table

Saponite:

Claims

Patent claims

1 . Process for the production of swellable layered silicates of the smectite type by hydrothermal pressure treatment of mixtures and / or coprecipitates of the components forming layered silicate in the presence of an excess of water and free bases, characterized in that a reaction mixture is introduced into the hydrothermal reaction stage, the base excess of which is by means of Ammonia is formed and that, if desired, at least a portion of the aqueous basic reaction medium is separated from the layered silicate formed in the preparation of the crude reaction product.

2. The method according to claim 1, characterized in that a reaction mixture containing at least predominantly oxidic and / or hydroxide reactants, which is essentially free of non-volatile foreign constituents, is introduced into the hydrothermal reaction.

3. Process according to Claims 1 and 2, characterized in that, in the presence of essentially volatile auxiliary components in the raw reaction mixture, at least one does not wash the raw reaction product intensively.

4. Process according to Claims 1 to 3, characterized in that the sheet silicates are freed from water and / or ammonia by drying - preferably at normal pressure and / or reduced pressures - and, if appropriate, a finely powdered solid product is obtained after comminution, where Drying temperatures up to about 300 C, preferably those in the range from 50 to 250 C may be preferred.

5. Process according to Claims 1 to 4, characterized in that synthetic swellable sheet silicates of the following general formula (I) are prepared

MgO. aMA bAI ₂ 0 ₃ cSiO. nH ₂ 0 (I)

in the mean

MM == NNaa ⁺ and / or Li with a Na / Li ratio equal to or greater than 1

A = F ^~ , OH ~ and / or 1/2 O ^2- as well as a, b, c and n numbers are according to a = 0.1 to 0.6 b = 0 to 0.3 c = 1.2 to 1 , 7 n = 0 to 3.0.

6. The method according to claims 1 to 5, characterized gekennzeich¬ net that one carries out the hydrothermal reaction at the autogenous pressure of the reaction system under reaction conditions.

7. The method according to claims 1 to 6, characterized gekennzeich¬ net that the hydrothermal reaction at temperatures of about 150 to 300 C, preferably from about 200 to 270 ° C with reaction times between 1 and 20 hours, preferably between 2 and 8 hours carries out.

8. Process according to Claims 1 to 7, characterized in that ammonia is used in amounts of 0.1 to 5 moles, preferably in amounts of 0.2 to 2 moles, based in each case on moles of magnesium oxide in the reaction mixture.