WO1992015539A1

WO1992015539A1 - Method for producing homogeneous, fine, pulverulent solids dispersions optionally containing active substances

Info

Publication number: WO1992015539A1
Application number: PCT/EP1992/000436
Authority: WO
Inventors: Friedrich BÖLSING
Original assignee: Dcr International Environmental Services Inc.
Priority date: 1991-03-01
Filing date: 1992-02-28
Publication date: 1992-09-17
Also published as: KR100220560B1; AU648391B2; JPH05507440A; NO301222B1; NO924190D0; NO924190L; CA2081307A1; EP0527984A1; AU1205592A

Abstract

Homogeneous, fine, pulverulent solids dispersions are produced by homogenizing an aqueous solids suspension with the educt of a reaction which requires water, e.g., calcium oxide, aluminium alcoholate, silicic acid esters or mixtures thereof. The reaction requiring water yields a solid reaction product. To ensure homogeneous charging of the resulting solids dispersion with active substances, a homogeneous mixture of the aqueous solids suspension and a solution or finely dispersed supsension of the active substances is homogenized with the educt of a reaction requiring water. Depending on the components, the solids dispersions, possibly charged with active substances, can be used in a wide range of agricultural applications and technical processes, and especially in environmental protection.

Description

Process for the production of homogeneous, fine, powdery solid dispersions, optionally containing active substances

B e s c h r e i b u n

Solid dispersions play an important role in the agricultural field and in technology. Examples are clay flours, which play an important role as soil improvers and as adsorbents in industrial processes. If finely dispersed solid dispersions from finely dispersed, water-containing precursors, e.g. to be produced from natural clay, this requires thermally complex drying processes with a subsequent mechanical homogenization. If finely dispersed solid dispersions are to be produced from coarse-grained solids or solid components, mechanically complex grinding or grinding processes are required to obtain solid dispersions which are largely finely dispersed and homogeneous; These mechanical processes are in any case limited by the fact that the grain size that can be achieved in this case is determined solely by the maximum technically achievable shear forces.

The invention is therefore based on the object of providing a process by which extraordinarily homogeneous and finely dispersed solid dispersions can be prepared without any particular technical outlay.

To achieve this object, a water-containing, finely dispersed solid suspension is mechanically homogenized with an educt of a water-consuming chemical reaction, for example with an alkaline earth metal oxide or an aluminum alcoholate or a silicic acid ester or a mixture of these compounds, and the homogenate is then left with the stoichiometric consumption required amount of water react completely. The water-consuming reaction chosen is a reaction in which a finely dispersed solid is formed from the educt; Accordingly, alkaline earth metal hydroxides or aluminum hydroxides - ^> or silicic acid are formed from the starting materials mentioned.

Aqueous, finely dispersed solid suspensions which can be used for the purposes of the invention are suspensions of finely dispersed solids in water. Finely dispersed substances in the sense of the invention are substances with particle sizes in the range of

> 0 to <250 micrometers, preferably in the range from 1 to 50 micrometers, which have a good adsorption capacity due to their structural characteristics. Examples are layered silicates, finely dispersed silica, aluminum oxides and aluminum hydroxides, precipitated chalk and iron oxides. Their pasty mixtures with water are referred to here as finely disperse solid suspensions.

The water content in the finely dispersed solid suspension may fluctuate within wide limits, provided that there is sufficient water on the one hand for the subsequent chemical reaction with an alkaline earth metal oxide or aluminum alcoholate and on the other hand that there is no longer any water, such as for the production of a powdery solid dispersion. The water content of the finely dispersed solid suspension is preferably adjusted such that a pasty, kneadable mass is present.

The water-containing, finely dispersed solid suspensions can be of natural or industrial origin. A pasty and kneadable, water-containing, finely dispersed solid suspension of natural origin is clay, as it is obtained in pits for the production of clay, and which can still be used according to the invention. Bleaching earth and clay flours are of industrial origin; if they are pasted with water, water-containing, finely dispersed solid suspensions are obtained which are likewise useful in the sense of the invention. In addition to clay, clay-like and clay-containing materials can also be used to produce water-containing, finely dispersed solid suspensions. If one speaks of clay-like and clay-containing materials, this refers solely to their adsorption capacity due to physical and structural characteristics and not to the chemical composition. Examples are clay-like or clay-like fly dusts, filter dusts, ashes and production residues, e.g. production residues from the food industry in the form of used bleaching earth, or e.g. red mud, a pasty mass vorweigeήd made of iron oxides and iron hydroxides, which is obtained in connection with the production of aluminum.

It is part of the essence of the invention that the water contained in the finely dispersed solid suspension is consumed uniformly in the chemical reaction with alkaline earth oxide or aluminum alcoholate, because only under this condition can a homogeneous powdery solid dispersion be formed. For this reason, water must verbrau¬-reaching reaction until such time as the starting material of water consuming reaction of FeststoffSus¬ is distributed pension uniform in. ^"This can be achieved if either the water-containing, finely dispersed Feststoffsuspen- sion as fast with the reactant homogenizes the water-consuming reaction, that the latter is uniformly distributed therein, before the water-consuming chemical reaction starts to any significant extent or by adding known reaction retarders to the water-containing, finely dispersed solids suspension, for example ammonia solution, alcohols, alkali metal sulfates and the like. , or that the starting material of the water-consuming reaction is pretreated in a corresponding manner, for example with alcohol or long-chain amines, fatty acids and the like. Instead of the pure starting materials, alkaline earth metal oxide or aluminum alcoholate or

Mixtures of alkaline earth metal oxides or aluminum alcoholates or silicic acid esters or mixtures of these compound classes can also be used. The clay products obtained according to the invention can be used as soil improvers or as earth building materials, for example for sealing landfills. This applies mutatis mutandis to all other named solid suspensions. Solid dispersions with aluminum hydroxide or silica can serve as effective adsorbents.

Numerous chemical and physical properties of active substances on a solid carrier change advantageously depending on their degree of dispersion. As a rule, the chemical reactivity increases the more finely divided a solid or liquid substance is as a reactant on a carrier. From a physical point of view, for example, the speed with which equilibria are set changes, for example with regard to adsorption or dissolution processes. With finely divided active ingredients on a solid carrier chemical and physical processes are possible which do not take place otherwise or only very slowly.

It is known that solid and liquid active ingredients can be mechanically applied to a solid carrier by grinding. A solid carrier can also be impregnated with an active ingredient solution and the suspension then dried. Suitable active ingredients can be evaporated onto a solid carrier. Finally, there is the possibility of converting active substances homogeneously and finely dispersed into a solid carrier in the course of a dispersing chemical reaction.

The methods mentioned are subject to certain limitations with regard to their applicability or have other disadvantages. There are limits to the milling of active ingredients insofar as the mechanically achievable shear forces are not sufficient to achieve an arbitrarily extensive fine distribution of the active ingredients in the regrind. The production of homogeneously loaded, powdery solid dispersions using an active ingredient solution or by vapor deposition is limited to soluble or vaporizable active substances and, because of the required technical outlay, is generally also expensive. The homogeneous fine distribution of active substances in the course of dispersing chemical reactions is limited to active substances which can be pre-distributed in the starting material of the dispersing chemical reaction. In addition, these starting materials, namely alkaline earth oxides, aluminum alcohols and silicic acid esters, are relatively expensive.

The invention therefore also has the object of producing powdery solid dispersions homogeneously loaded with active ingredients in a technically simple and thus economical manner and largely avoiding limitations and disadvantages.

To achieve this object, a water-containing, finely disperse solid suspension is mechanically homogenized with active substances or mixtures of active substances, and the homogenate is then homogenized with an alkaline earth oxide or an aluminum alcoholate.

According to the concept of the invention, the latent adsorption capacity of the solids in finely dispersed form in a water-containing solid suspension, which are completely coated with water in this environment and are therefore practically incapable of adsorption, is made usable when the water-containing solid suspension is present Active substances which can be adsorbed, distributed homogeneously and which may be present as a solution or in a finely dispersed suspension, by a water-consuming reaction, for example by the hydration reaction of an alkaline earth metal oxide or by the hydrolysis of an aluminum alcoholate, chemically remove the water, so that the active substances be adsorptively bound to the surface of the now largely water-free solid. It is part of the essence of the invention that the finely disrupted reaction resulting from the starting material of a water-consuming reaction persistent, solid reaction product, for example finely dispersed alkaline earth metal or aluminum hydroxide made of alkaline earth oxide or aluminum alcoholate, also has an adsorptive effect.

The advantage of the invention is based on the fact that, unlike in mechanical dispersing, even small amounts of active ingredient can be homogeneously distributed on a solid carrier, and that, unlike in the case of a homogeneous fine distribution of active ingredients in the course of dispersing chemical reactions, the indispensable prerequisite there. namely the predistributability of the active ingredients to be distributed in the starting material of the dispersing chemical reaction, for example in an alkaline earth oxide, aluminum alcoholate or silicic acid ester is absolutely not necessary. On the contrary, according to the invention, in order to produce a powdery solid dispersion homogeneously loaded with active ingredients, the active ingredient is mechanically homogenized with a water-containing, finely dispersed solid suspension and the homogenized product is only then homogenized with an alkaline earth metal oxide or aluminum alcoholate. In this way, the proportion of alkaline earth oxide or aluminum alcoholate required to produce a powdery solid dispersion homogeneously loaded with active ingredients can be reduced considerably, in favorable cases to about a tenth of the amount required for a dispersing chemical reaction.

Here, active substances are substances that, in contrast to the substances in the solid suspension that are considered to be mere carriers, are particularly effective in chemical and physical terms in their finely divided state. In this context, too, it is not the physical and chemical properties of the substances involved that matter, but only the role that is assigned to them for the respective application. This. will be explained using two examples. Natural clay is homogenized by kneading with a concentrated aqueous solution of sodium sulfide; The resulting plastic mass in the subsequent water-consuming chemical reaction with about 15% hydrophobic calcium oxide, based on the amount of clay used, results in a powdery solid dispersion homogeneously loaded with sulfide ions. The finely divided active ingredient sulfide ions is known to be a highly reactive precipitation reagent with which numerous toxic heavy metals can be converted into water-insoluble heavy metal sulfides by precipitation and can thus be chemically fixed and immobilized. For this purpose, soils, fly ash, slags contaminated with heavy metals are mixed with the solid dispersion mentioned and then compacted to give a solid body. Coarse-particle contaminated materials, for example chimney linings, foundation parts, equipment and the like, are embedded in the solid dispersion as such or in a mixture with other materials which are advantageous from a soil mechanical point of view, with compaction. The soil mechanics aspect plays a particularly important role in the treatment of heavy metal contaminated sewage sludge with its soil mechanically unstable gel structures in order to be able to deposit them safely after homogenization with the solid dispersion mentioned in the form of soil mechanically stable and stable soil bodies. Mixing in suitable waste materials contaminated with heavy metals, such as slags and ashes, is particularly advantageous from an economic point of view.

According to a particularly effective process variant, a part of the clay is first kneaded with an aqueous alkali sulfide solution and a second part with a fine-grained aqueous suspension of iron sulfate. If the two subsets are then homogenized, iron sulfide which is very finely divided in situ and embedded in the clay structure is formed. The still pasty mass is now chemically converted with about 20%, based on the total amount of clay, of normal, ie not hydrophobicized, calcium oxide. The stoichiometric proportions are chosen so that there is a slight excess of iron ions, for example 10%. The active ingredient now consists of iron sulfide, which is considered to be water-insoluble. Because of the much smaller solubility product of the sulfides of toxic heavy metals, however, they are reprecipitated after being mixed into materials contaminated with heavy metals. In this way, a particularly effective immobilization of heavy metals is possible without endangering the groundwater through the direct use of reliable, ie water-soluble alkali sulfides.

In the aforementioned example and in the associated process variant, substances are used with the sulfides mentioned which, owing to their chemical reactivity, in particular as a precipitation reagent, can be readily addressed as active ingredients. Active substances within the meaning of the invention can also be substances that are considered chemically inert.

If, for example, hard bitumen is melted, kneaded with clay and, as soon as it is homogeneous, this mass is mixed with calcium oxide, preferably with hydrophobic calcium oxide, and then kneaded again, the water-consuming hydration reaction of the calcium oxide begins after some time. and the originally pasty mass disintegrates into a powdery, homogeneously loaded with hard bitumen

Solid dispersion. The calcium hydroxide contained in this solid dispersion is known to be in no way inert from a chemical point of view, but has strongly basic properties and can therefore be easily, e.g. react with carbon dioxide, while the hard bitumen also contained in this solid dispersion is completely inert from a chemical point of view.

Nevertheless, the mixture of clay particles and calcium hydroxide present in the solid dispersion is the carrier and. the hard bitumen the active ingredient if the task. it consists, for example, of highly toxic organic pollutants, such as polychlorinated biphenyls (PCB) or dioxins and dibenzofurans (PCDD / PCDF), for example as ingredients in filter dusts from waste incineration plants or as contaminants in soils, by irreversible immobilization. For this purpose, contaminated flue dusts or soils are mixed with a powdered solid dispersion loaded with hard bitumen, which was produced using clay and calcium oxide, and a soil body is produced from the mixture with compaction. After a short time, the finely dispersed hard bitumen in the solid matrix incorporated the organic pollutants, because of their good solubility in the solid solvent hard bitumen. Leaching tests under long-term conditions and using trace analysis methods prove that. organic pollutants treated in accordance with the invention remain permanently and completely immobilized. Other high-boiling organic inert substances, such as hard paraffin, petroleum jelly or mineral oil, can take the place of hard bitumen.

It is impossible to enumerate the individual active substances and active substance mixtures, because, according to known aspects, their selection results automatically from the respective task. It is known, for example, that trace elements in different concentrations and bioavailability are required in the production of plant substrates. These include copper, iron, manganese, zinc, molybdenum and boron, the water-soluble compounds of which are mixed mechanically and used in the form of heterogeneous concentrates. The disadvantage of these preparations is that the trace elements mentioned are not uniformly available to the plant because uniform distribution in the substrate is impossible. If, on the other hand, the same compounds of the trace elements mentioned are first kneaded into a clay matrix and distributed uniformly in this way, an extremely finely dispersed solid preparation is obtained after homogenizing this mixture with calcium oxide, in which the active ingredients are extremely uniform. By co-dispersing wine and citric acid it is in the hand to predict the bioavailability of the trace elements mentioned. If you want to convert the trace element compounds, with or without tartaric acid, individually into a powdery solid dispersion and only want to mix them later in the required quantity ratio for the application, then it is also advisable to co-distribute a hydrophobing agent because then within the mixture of the individual powdery solid dispersions no adverse interactions of the compounds of the trace elements with each other are possible.

In the same way, plant nutrients of the most varied types can be processed into extraordinarily homogeneous long-term fertilizers, provided they are stable in the resulting alkaline medium.

The number of active ingredients that can be used in the environmental protection field is unmanageably large because the number of pollutants with problems is so large. Theoretically, for every pollutant, but at least for each pollutant class, there are active substances within the meaning of the invention which can be used as reaction partners, for example as precipitation, condensation or addition partners, for immobilization and detoxification, to name just a few examples to call. In this context, high-boiling organic phases are particularly important as active ingredients for the adsorption and absorption of inorganic and organic pollutants, because this form of immobilization and physical fixation is particularly simple and comprehensive; One example among many is the absorptive removal of pollutants from waste gases from waste incineration plants using long-chain amines as active ingredients. In addition, however, it is also possible to incorporate other active ingredients into the high-boiling organic phase which are capable of a chemical interaction with pollutants and therefore shift the equilibrium position in favor of complete absorption, for example through long-chain ones A in a bituminous phase. The relationship between the active substances to be selected and the task to be solved is familiar to any person skilled in the art and therefore requires no further explanation; it is known to any person skilled in the art that 5 finely dispersed metals such as magnesium or aluminum can be used for the dehalogenation of halogen-containing aromatics.

In the second example listed above, in which the use of hard bitumen as an active ingredient is explained, hydrophobic calcium oxide is preferably used. It is part of the essence of the invention that the water contained in the finely dispersed solid suspension is consumed uniformly in the chemical reaction with alkaline earth oxide or aluminum alcoholate, because only under this condition can a homogeneously loaded powdery solid dispersion be formed. For this reason, the water-consuming reaction may only start when the alkaline earth metal oxide or aluminum alcoholate is uniformly distributed in the homogenate of active ingredient and solid suspension. This can be achieved if either the homogenate of water-containing, finely dispersed solid suspension and active substances is homogenized with the alkaline earth metal oxide or aluminum alcoholate so quickly that the latter are uniformly distributed in the homogenate before the water-consuming chemical reaction occurs significant extent or by adding known reaction retarders to the water-containing, finely dispersed solid suspension, for example Ammonia solution, alcohols, alkali sulfates and the like, or that the alkaline earth oxide or aluminum alcoholate is pretreated in a corresponding manner, e.g. with alcohol or long chain amines, fatty acids and the like.

Instead of the pure alkaline earth oxides or aluminum alcoholates, it is also possible to use mixtures of alkaline earth oxides or aluminum alcoholates or mixtures of both classes of compounds. For applications of such powdery solid suspensions homogeneously loaded with active substances for agricultural or technical purposes, in particular also in the field of environmental protection, it is advantageous if an excess of calcium oxide is preferred by appropriate process control or by a subsequent mixture ¬ wise on hydrophobic calcium oxide. In this way, cohesive contaminated materials can be broken down in one operation in such a way that the active ingredients are uniformly distributed in the medium and the pollutants are completely detected and rendered harmless.

example 1

100 parts by weight of a natural plastic clay are homogenized in a kneader with 18 parts by weight of a calcium oxide hydrophobicized with 1% fatty acid. The hydration reaction which begins after about 5 minutes is allowed to run outside the kneader; this results in an extraordinarily homogeneous solid dispersion of calcium hydroxide in clay, which is so homogeneous that the components themselves can no longer be seen under the microscope.

Variant The plastic clay is kneaded first with 2% potassium sulfate as a reaction retardant and then with non-hydrophobized calcium oxide. The hydration reaction only begins after about 20 minutes.

variant

Instead of clay, red mud is used or a paste consisting of 70 parts by weight of dry, used bleaching earth and 30 parts by weight of water.

variant

Instead of calcium oxide, the stoichiometric equivalent of mixed aluminum alcoholate or silicic acid esters be applied; in these cases the alcohol released in the hydrolysis evaporates; it can be recovered by condensation.

Example 2

70 parts by weight of clay, 7.6 parts by weight of iron sulfate FeSO. x 7H 0.3 parts by weight of sodium sulfide Na_S (60%) and 4 parts by weight of water are homogenized in a kneader. The homogenate is homogenized with 15.4 parts by weight of calcium oxide. 100 parts by weight of a pulverulent solid dispersion which is homogeneously loaded with 2% iron sulfide FeS and can be used to precipitate heavy metals in contaminated materials. The proportion of iron sulfate is such that there is a 20% excess in relation to the stoichiometrically required amount; In this way it is prevented that soluble alkali sulfide, for example in the treatment of contaminated soils or contaminated production residues, can get into the groundwater in the course of the treatment according to the invention. The clay in this example can be replaced in whole or in part by pastes of dry, used bleaching earth with water, for example 77 parts by weight of used bleaching earth from the food industry with 23 parts by weight of water or with so-called red mud, or by pasting a finely disperse Filter dust with so much water that a clay-like matrix is created. The addition of reaction retarders is not necessary in this example because, in analogy to the alkali sulfates, the iron sulfate already delays the chemical reaction of the calcium oxide in such a way that complete homogenization is possible before the water-consuming reaction of the calcium oxide begins.

Example 3

In a variant of Example 2, 35 parts by weight of clay are homogenized with a suspension of 7.6 parts by weight of iron sulfate and 2 parts by weight of water in a compulsory mixer; 35 parts by weight of clay are mixed with an aqueous solution of

Homogenize 3 parts by weight of sodium sulfide (60%) in 2 parts by weight of water in a compulsory mixer.

After homogenization, both portions are homogenized in a compulsory mixer and then homogenized with 15.4 parts by weight of hydrophobic calcium oxide. The result is a powdery solid dispersion which is loaded extremely homogeneously with 2% iron sulfide FeS and which, like that from Example 1, can be used.

Example 4

In a variant of example 2 or 3, the separately prepared homogenates of clay and iron sulfate or of clay and sodium sulfide are homogenized with 7.7 parts by weight of calcium oxide and hydrophobic calcium oxide, respectively. Mixing the two pulverulent solid dispersions loaded with iron hydroxide or sodium sulfide gives a preparation which, in the presence of an excess of hydrophobic calcium hydroxide, can be used particularly effectively and at the same time in an environmentally friendly manner for the treatment of heavy metal-containing, binding materials because, on the one hand, the The heavy metals are precipitated immediately with the aid of the alkali sulfide, but on the other hand no trace of this sulfide can get into the environment, because it is trapped by the iron hydroxide present, without the precipitating effect on heavy metals which have not yet been eliminated becomes.

Example 5

56 parts by weight of clay are plasticized with 15 parts by weight of water and preheated to 70 ° C. This water-containing, finely disperse solid suspension is homogenized with 35 parts by weight of melted bitumen B 80 in a kneader. There; The homogenate is then homogenized with 56 parts by weight of calcium oxide, which has been made hydrophobic with 1% fatty acid. siert. The result is a powdery solid suspension loaded homogeneously with bitumen, which can be used in the environmental protection field for the isolation and protection of landfill bodies and for the immobilization of nonionic, inorganic and organic pollutants. To this

For this purpose, they are mixed, for example, in a ratio of 1: 4 with a contaminated material which contains, for example, halogenated dibenzodioxins or dibenzofurans in the ppm range. The exact required proportions are determined by simple manual tests, whereby the absorption capacity of the pure bitumen is determined in relation to the existing type and quantity of pollutant. In order to absorb pollutants with certain functional groups, the melted bitumen is mixed, for example, with the required amount of an active ingredient which contains a functional group capable of reacting with the pollutant, so that the adsorption equilibrium is shifted towards complete absorption becomes. For the treatment of pollutants that cannot be immobilized in the alkaline range, a commercially available aluminum mixed alcoholate, e.g. made of aluminum isopropanolate and aluminum isobutanolate. At this point, the clay can be replaced particularly advantageously by red mud, because this finely dispersed system adsorbs the dioxins and furans mentioned particularly effectively in the dry state.

Example 6

150 parts by weight of clay with a water content of 23% are plasticized with 10 parts by weight of water in a kneader and 1 part by weight of a water-soluble salt of copper or manganese, or zinc, or molybdenum or boron or iron, for example in the form of the corresponding copper, iron, manganese and zinc sulfates, or as ammonium molybdate or potassium metaborate. The homogenates are then mixed in with an alkaline earth oxide mixture of 90% calcium oxide and 10% magnesium oxide, which has been made hydrophobic with 0.2% fatty acid homogenized in a kneader. The individually obtained homogeneous, powdery solid dispersions loaded with the trace elements mentioned are mixed in a downpipe mixer in a proportion required according to the task. An additive for substrate production from peat or compost is obtained. The hydrophobic properties of the additive cause rapid mixing even with very moist peat or compost. If one speaks here of the mixing ratio according to the task at hand, this means the different needs of the plants in their different growth phases. In the event that the bioavailability of individual components is to be increased above average, the clay in the corresponding preparation is additionally homogenized with 1 part by weight of tartaric acid or for a further increase in bioavailability with 1 part by weight of citro nenoic acid.

Example 7

100 parts by weight of clay or clay are plasticized with 10 parts by weight of water and homogenized with 20 parts by weight of calcium cyanamide; the homogenate is then homogenized with 10 parts by weight of hydrophobic calcium oxide. The solid dispersion obtained in this way can be used as long-term nitrogenous fertilizer in agriculture.

Example 8

In a combination of Examples 2 and 5, 100 parts by weight of clay are mixed with a suspension of 32 parts by weight of iron sulfate in 7 parts by weight of water, with 8 parts by weight of sodium sulfide and with 30 parts by weight. Parts of melted bitumen are homogenized one after the other in a compulsory mixer and then homogenized with 28 parts by weight of a calcium oxide hydrophobicized with 0.5% fatty acid. The resulting powdery solid dispersion loaded with the active ingredients iron sulfide and bitumen homo¬ gen can be used for simultaneous irreversible immobilization of heavy metals and ultra poisons, for example PCDD / DF in appropriately contaminated filter dusts and ashes from waste incineration plants.

Example 9

A double excess of the stoichiometrically required amounts of dipotassium hydrogen phosphate, iron sulfide and calcium carbonate are converted analogously to the procedure in Example 1 separately into homogeneous solid dispersions using calcium oxide which has been hydrophobized with 1% fatty acid. The mixture of the individual solid dispersions is particularly suitable for irreversibly immobilizing heavy metal ions in sewage sludge, compost, river and harbor silt by precipitating the individual heavy metals as carbonates, sulfides and phosphates. Arsenic and antimony can also be chemically fixed in this way. For this purpose, the solid dispersions mentioned are mixed into the waste materials to be treated simultaneously with additional, slightly hydrophobicized calcium oxide, e.g. through synchronous feeding into a downpipe mixer. This makes it possible for the first time to store large quantities of these waste materials in an environmentally neutral manner without further safety measures or to use them as earth building material, e.g. for the purpose of landscaping. The required proportions are determined by the soil mechanical requirements; they can be found in the known proficiency tests, e.g. by determining the Proctor density.

Example 10

100 parts by weight of clay or a paste of finely dispersed aluminum hydroxide or zeolite or bentonite with water or used, moist bleaching earth, or 100 parts by weight of a mixture of the solid suspensions mentioned are mixed with 50 parts by weight of a long-chain amine, for example stearylamine, and 10 parts by weight of an aminosilane, for example a trialkoxy aminosilanε, homogenized in a kneader and then homogenized with 500 parts by weight of hydrophobic calcium oxide. The resulting dry, powdery and homogeneous solid dispersion, which contains an excess of calcium oxide, can be used as such or after the hydration reaction has elapsed, with not quite the stoichiometrically required amount of water in relation to the calcium oxide excess, in the form of the subsequent product, ie with calcium hydroxide as the predominant component in terms of quantity, use for the greatest possible absorption or absorption of pollutants in the exhaust gases of waste incineration plants, in particular of halogenated dibenzodioxins and dibenzofurans.

Example 11

100 parts by weight of clay, or a paste of finely dispersed

Aluminum hydroxide or zeolite or bentonite with water, or used, moist bleaching earth, or 100 parts by weight of a mixture of the solid suspensions mentioned are homogenized with 50 parts by weight of an alkali or alkaline earth metal sulfide in a kneader and then with 150 parts by weight of hydrophobic Calcium oxide homogenized. The resulting dry, powdery and homogeneous solid dispersion, which contains an excess of calcium oxide, can, because of its hydrophobic character, be easily incorporated into the surface of heaps which consist of production residues containing heavy metals. In this way, a comprehensive depot with precipitation reagents is created, which, due to slow desorption processes

(Sulfide ions) or, due to their poor solubility (calcium hydroxide and calcium carbonate from calcium oxide), are only very slowly introduced into the stockpile with rainwater as a vehicle and cause precipitation reactions there in situ. The absolute amount of precipitation reagents required for this and thus the layer thickness of the depot can easily be determined from the height of the heap and the average concentration of precipitated heavy metals in the heap. An analogous procedure is used to immobilize pollutants in other deposited deposits and landfills.

Claims

Patent claims

1. A process for the preparation of homogeneous, finely dispersed solids dispersions, characterized in that a water-containing, finely dispersed solids suspension is mechanically homo nized with an alkaline earth metal oxide, aluminum alcoholate, silicic acid ester or a mixture of these compounds, and the homogenate is then ometric with the stδc the required amount of water can react.

2. Method according to claim 1, characterized in that materials of natural or industrial origin are used as the water-containing, finely dispersed solid suspension.

3. The method according to claim 1, characterized in that the water-containing, finely dispersed solid suspension is obtained from finely dispersed, dry materials of natural or industrial origin by adding water.

4. The method according to claim 1, characterized in that clay flour, clay and clay-like and clay-containing materials are used as the water-containing, finely dispersed solid suspension of natural origin.

5. The method according to claim 1, characterized in that production residues, such as used bleaching earth and red mud, are used as the water-containing, finely dispersed solid suspension of industrial origin.

6. The method according to any one of claims 1 to 5, characterized ge indicates that calcium oxide is used as the alkaline earth oxide.

7. The method according to any one of claims 1 to 6, characterized ge indicates that the alkaline earth metal is pretreated with reaction delayers.

8. The method according to claim 7, characterized in that the reaction retardant is a hydrophobicizing agent.

9. The method according to any one of claims 1 to 8, characterized in that the reaction retarders are added to the solid suspension.

10. The method according to any one of claims 1 to 9, characterized in that a commercially available liquid mixed alcoholate is used as the aluminum alcoholate.

11. The method according to any one of claims 1 to 10, characterized in that mixtures of commercially available silicic acid esters are used as silicic acid esters.

12. The method according to claim 1, characterized in that for the production of powdery solid dispersions homogeneously loaded with active ingredients, a water-containing, finely dispersed solid suspension is mechanically homogenized with active ingredients, and the homogenate then with an alkaline earth metal oxide, aluminum alcoholate, silica ester or a mixture of these Connections is homogenized.

13. The method according to claim 12, characterized in that the active substances are formed in situ during the preparation of the solid dispersion.

14. The method according to claim 12 or 13, characterized in that agriculturally usable as active ingredients

Substances and mixtures of substances are used.

15. The method according to claim 14, characterized in that fertilizers, trace elements, crop protection agents or mixtures thereof are used as agriculturally usable substances.

16. The method according to claim 12 or 13, characterized gekennzeich¬ net that inorganic or organic reactants for detoxification, immobilization or chemical fixation of pollutants are used as active ingredients.

17. Verfa ren according to claim 16, characterized in that as organic reactants reducing metals, such as K-magnesium or aluminum, or precipitation reagents, such as S__i-fide, carbonates, phosphates, are used.

18. The method according to claim 12 or 13, characterized gekennzeich¬ net that inorganic or organic adsorbents and absorbents for immobilization and adsorptive or absorptive fixation of harmful substances are used as active ingredients.

19. The method according to claim 18, characterized in that high-boiling inert substances are used as organic adsorbents or absorbents.

20. The method according to claim 19, characterized in that hard paraffin, petroleum jelly, bitumen and bituminous substances are used as high-boiling inert materials.

21. Use of the solid suspension according to one of claims 1 to 20 for agricultural or technical purposes.

22. Use of the solid dispersion according to claim 21 with an excess of calcium oxide and / or aluminum alcohol for agricultural or technical purposes.

23. Use of the solid dispersion according to one of claims 1 to 20 for the isolation, embedding and detoxification of pollutants.

24. Use of the solid dispersion according to one of claims 1 to 20 for removing pollutants from exhaust gases.

25. Use of the solid dispersion according to one of claims 1 to 20 for the dehalogenation of halogen-containing pollutants.