AU648391B2 - Homogeneous, finely dispersed, pulverulent solid dispersions - Google Patents

Description

OPI DATE 06/10/92 AOJP DATE 12/11/92 (51) Internationale Patentkiassirikation 5 3/02, 9/00, C02F I11/00 3/00, A62D 3/00 APPLN. ID 12055 92 PCT NUMBER PCI/EP92/00136 ERTRAG OBER DIE ENTWESENS (PCT) Al (11) Internationale Veriiffentlichungsnummer: (43) Internationales Veroffentlichungsdatum: 17. Sept WO 92/15539 ember 1992 (17.09.92) (21) Internationales Aktenzeichen: PCT/EP92/00436 (22) Internationales Anmeldedatum: 28. Februar 1992 (28.02.92) Priori titsdaten P 4106 515.8 P 4106 516.6 1. irz 1991 (01.03.91) 1. Miirz 1991 (01.03.91) (71) Anmelder (flir alle Bestimmungsswtaaen ausser US): DCR INTERNATIONAL ENVIRONMENTAL SERVICES INC. [JP/JP]; European Division, 17-7, Todoroki 5-chome, Setagaya-ku, Tokyo 158 (JP).

(72) Erfinder; und Erfinder/Anmelder (nur ffir US) BOLSING, Friedrich [DE/DE]; Danziger Stra~e 5, D-3067 Lindhorst (DE).

(74)Anwalt: EGGERT, R~derscheidtstr. 1, D-5000 K6ln 41 (DE).

(81) Bestimmungsstaaten: AT (europiiisches Patent), AU, BE (europfiisches Patent), BR, CA, CH (europ~isches Patent), DE (europtiisches Patent), DK (europ~isches Patent), ES (europfiisches Patent), FR (europ~isches Patent), GB (europ~isches Patent), GR (europliisches Patent), IT (europfiisches Patent), JP, KR, LU (europilisches Patent), MC (europiiisches Patent), NL (europiiisches Patent), NO, RO, RU, SE (europdisches Patent), us.

Ver6ffentlicht Mit internationalem Recherc/ienberich.

5J4~ (54)Title: METHOD FOR PRODUCING HOMOGENEOUS, FINE, PULVERULENT SOLIDS DISPERSIONS OPTIO- NALLY CONTAINING ACTIVE SUBSTANCES (54) Bezeichnung: VERFARREN ZUR HERSTELLIJNG HOMOGENER, FEINER, PULVERFORM IGER, GEGEBENEN FALLS WIRKSTOFFE ENTHALTENDER FESTSTOFFD)ISPERSIONEN (57) Abstract Homogeneous, Fine, pulverulent solids dispersions are produced by homogenizing an aqueous solids suspension with the educt of a reaction which requires water, caicium 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 aqueonz, 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 technicai processes, and especially in environmental protection.

(57) Zusamnmenfassung Zur Herstellung einer homogenen, feinen, pulverflirmigen Feststoffdispersion wird eine wasserhaltige Feststoffsuspension mit dem Edukt einer Wasser verbrauchenden Reaktion, z.B. Calciumoxid, Aluminiumalkoholat, Kieseisgureester oder deren Gemisch homogenisiert. Die Wasser verbrauchende Reaktion fiihrt dabei zu einem festen Reaktionsprodukt. Zur homogenen Beladung der entstehenden Feststoffdispersion mit Wirkstoffen wird emn homogenes Gemisch aus der wasserhaltigen Feststoffsuspension und einer L6sung oder feindispersen Suspension der Wirkstoffe mit dem Edukt einer Wasser verbrauchenden Reaktion homogenisiert. Die gegebenenfalls mit Wirkstoffen beladenen Feststoffdispersionen sind je nach den verwendeten Komponenten vielfgltig einsetzbar im landwirtschaftlichen Bereich und in technischen Prozessen, insbesondere auch im Umweltschutzbeyeich.

PCT/EP92/00436 PROCESS FOR THE PRODUCTION OF HOMOGENEOUS, FINELY DISPERSED, PUL- VERULENT SOLID DISPERSIONS, IF NECESSARY HOMOGENEOUSLY CHARGED WITH ACTIVE COMPOUNDS, AND THE USE OF PRODUCTS THEREBY.OBTAINED.

DESCRIPTION

Dispersions of solids play an important part in agriculture and in engineering. Examples include clay powders,' which are important both as soil conditioners and as adsorption agents in industrial processes. Producing finely dispersed solid dispersions from finely dispersed aqueous intermediates such as natural clay calls for drying processes requiring large amounts of heat, followed by mechanical homogenisation. Producing finely dispersed solid dispersions from coarse-particle solids or solid constituents calls for mechanically complex grinding or comminution operations, in order to obtain solid dispersions comprising more or less fine homogeneous particles; however, there are limits to these mechanical operations by virtue of the fact that the specific grain size attainable for each material is determined solely by the maximum shear forces that can be attained by engineering.

It is therefore the object of this invention to provide a process that allows extremely homogeneous finely dispersed solid dispersions to be produced without the need for complex engineering solutions.

To achieve this object, an aqueous, finely dispersed suspension is homogenized mechanically with an educt of a water-consuming chemical reaction, e.g. with an alkaline earth oxide or an aluminium alcoholate or a silicic acid ester or a mixture of these compounds, and the educt of a water-consuming chemical reaction in the homogeneous mix is then allowed to react with the stoichiometric amount of water.

The water-consuming reaction is selected from reactions in whi-h finely dispersed solids are formed; said educts accordingly give rise to the formation of alkaline earth hydroxides, aluminium hydroxide and silica respectively.

The aqueous, finely dispersed suspensions suitable 'or the purposes of the invention are suspensions of finely diopersed solids in water. Finely dispersed substances within the meaning of the invention are substances having particle sizes within the range from 0 to 250 micrometer, preferably within the range from 1 to 50 micrometer, whose structural characteristics give them a good adsorption capacity. Examples include laminated silicates, finely dispersed silica, aluminium oxides and aluminium hydroxides, precipitated chalk and iron oxides.

Paste-like mixtures of these with water are referred to here as finely dispersed suspensions.

The proportion of water in the finely dispersed suspension may vary within broad limits, provided, on the one hand, that PCT/EP92/00436 sufficient water is present for the subsequent chemical reaction of said water-consuming educts and, on the other hand, that no more than the permitted quartity of water for producing a pulverulent solid dispersion ispresent. The water content of the finely dispersed suspension is preferably adjusted to give a paste-like, kneadable material.

The aqueous, finely dispersed suspensions may be of natural or industrial origin. Clay, as extracted from pits for the production of earthenware, is a paste-like and kneadable, aqueous, finely dispersed suspension of natural origin, and can be employed without modification in accordance with the invention.

Bleaching earth and clay powders are industrial in origin; mixing them with water into a paste produces aqueous, finely dispersed suspensions which are likewise suitable for use under the invention.

In addition to clay, clay-like and clayey materials can also be used to produce aqueous, finely dispersed suspensions.

The terms clay-like and clayey materials, as used here, refer solely to the adsorption capacity of such materials which is a result of their physical and structural characteristics, not to their chemical composition. Examples include clayey or claylike flue-dusts, filter dusts, ashes and industrial residues and waste material, e.g. waste materials from the food industry in the form of spent bleaching earth, or, say, red mud from the Bayer process, a paste-like compound chiefly comprising iron oxides and iron hydroxides, which is a by-product of aluminium production.

It is an essential aspect of the invention that the water contained in the finely dispersed suspension is consumed uniformly in the chemical reaction with alkaline earth oxide or aluminium alcoholate or silicic acid esters, because only then can a homogeneous powdered solid dispersion be produced. For this reason the water-consuming reaction must not be allowed to begin until the educt of the water-consiming reaction has been uniformly distributed in the suspension. This can be achieved either by homogenizing the aqueous, finely dispersed suspension so quickly with the educt of the water-consuming reaction that said educt is uniformly distributed therein before the waterconsuming chemical reaction has appreciably begun, or by adding conventional reaction retarders to the aqueous finely dispersed suspension, e.g. ammonia solution, alcohols, alkali sulfates and the like, or else by suitably pre-treating the educt of the water-consuming reaction, e.g. with alcohols or long-chain amines, fatty acids and the like. In place of the pure educts alkaline earth oxide or aluminium alcoholate or silicic acid ester, it is also possible to use mixtures thereof.

The clay products obtained in accordance with the invention can be used as soil conditioners or as earth construction material, e.g. to seal off waste dumps. This similarly applies to all other suspensions designated. Solid dispersions with aluminium hydroxide or silica can be used as effective adsorption agents.

PCT/EP92/00436 Numerous chemical and physical properties of active compounds on a solid carrier advantageously change in response to their degree of dispersion. Generally speaking, the chemical reactivity of a solid or liquid substance acting as a reactant increases, the more finely dispersed it is on a carrier. One example of the physical effect is the change in the speed with which equilibrium states are reached, for instance in respect of adsorption or solution processes. When active compounds are finely dispersed on a solid carrier, chemical and physical processes become possible that would otherwise not, or only very slowly, take place.

It is known that solid and liquid active compounds can be put onto a solid carrier by mechanical means using comminution. It is also possible to impregnate a solid carrier with a solution of an active compound and then dry the suspension. Suitable active compounds can be put onto a solid carrier by vacuum deposition. Lastly it is possible to transfer active compounds homogeneously and in a finely dispersed form into a solid carrier in the course of a dispersing chemical reaction.

The foregoing processes are subject to certain limitations as to their applicability or else have other drawbacks. For instance, the comminution of active compounds is limited by the fact that the shear forces that can be achieved by mechanical means are not sufficient to produce as fine a dispersion as may be required of the active compounds in the material being ground. The production of homogeneously charged, powdered solid dispersions using a solution of an active compound or by vacuum deposition is restricted to soluble or volatile active compounds and, on account of the technical complexity required, is usually also costly. The option of very finely dispersing active compounds homogeneously in the course of dispersing chemical reactions is restricted to active compounds that can be dispersed beforehand in the educt of the dispersing chemical reaction. Added to this is the fact that these educts, notably alkaline earth oxides, aluminium alcoholates and silicic acid esters, are relatively expensive.

It is therefore the object of this invention to produce powdered solid dispersions charged homogeneously with active compounds by a method that is technically simple and hence also economic, at the same time largely avoiding limitations and drawbacks.

To achieve this object, an aqueous, finely dispersed suspension is homogenized by mechanical means with active compounds or mixtures of active compounds, and the resulting homogenized mix is then homogenized with an alkaline earth oxide or an aluminium alcoholate or a silicic acid ester or a mixture thereof.

The idea underlying the invention exploits the latent adsorption capacity of the solids present in a finely dispersed form in an aqueous suspension, said solids being completely coated \with water in this environment and hence practically incapable PCT/EP92/00436 of adsorption, if the water is chemically removed from the aqueous suspension in the presence of homogeneously dispersed active compounds capable of adsorption, and which may be in the form of a solution or in a finely dispersed suspension, by means of a reaction that consumes water, for example a hydration reaction of an alkaline earth oxide or by hydrolysis of an aluminium alcoholate, with the result that the active compounds are adsorptively bound on the surface of the now largely anhydrous solid. It is also an essential aspect of, the invention that the finely dispersed solid reaction product simultaneously resulting from the educt of a water-consuming reaction, for example finely dispersed alkaline earth hydroxide or aluminium hydroxide from alkaline earth oxide and aluminium alcoholate respectively, likewise becomes adsorptively active.

The advantage of the invention lies in the fact that, unlike with mechanical distribution, it is also possible to disperse very small amounts of active compounds homogeneously onto a solid carrier, and that, unlike with a homogeneous very fine dispersion of active compounds achieved in the course of dispersing chemical reactions, the indispensable prerequisite for the latter, viz. the fact that it must be possible to disperse the active compounds for dispersion beforehand in the educt of the dispersing chemical reaction, e.g. in an alkaline earth oxide, aluminium alcoholate or silicic acid ester, is not necessary at all. Quite the contrary: under the invention to produce a pulverulent solid dispersion charged homogeneously with active compounds, the active compound is homogenized by mechanical means with an aqueous, finely dispersed suspension and the resulting homogenized mix only then homogenized with an alkaline earth oxide or aluminium alcoholate. This allows the proportion of alkaline earth oxide or aluminium alcoholate required to produce a powdered solid dispersion charged homogeneously with active compounds to be substantially reduced, in favourable cases to around one-tenth the amount needed for a dispersing chemical reaction.

The term active compounds refers here to substances which, unlike the substances of the suspension regarded merely as the carrier substance, are particularly active chemically and physically in their finely dispersed state. Likewise in this connection, the physical and chemical properties of the compounds concerned are not important per se, but only in relation to the part that they will play in the particular application envisaged. This will be illustrated by means of two examples.

Natural clay is homogenized by kneading it with a concentrated aqueous solution of sodium sulphide; in the subsequent waterconsuming chemical reaction with some 15% hydrophobic calcium oxide, based on the amount of clay used, the resulting plastic material produces a pulverulent solid dispersion homogeneously charged with sulfide ions. As is known, the finely dispersed active compound, sulfide ions, is a highly reactive precipitation reagent, by means of which numerous toxic heave metals can be converted by precipitation into water-insoluble heavy metal Ssulphides and thus chemically fixed and immobilized. To this 41

,IA

INTERNATIONALER RECHERCHENBERICHT PCT/EP 92/00436 IntenmtionWsi Aktenz mlc PCT/EP92/00436 end, soils, fly ashes or slags contaminated with heavy metals are mixed with said solid dispersion and then compacted into a solid material. Large lumps of contaminated materials, for example chimney linings, foundation sections,' equipment and the like, are embedded in said solid dispersion either as such or in a mixture with other materials having advantages in terms of soil mechanics and the resulting mix is then compacted. The question of soil mechanics is of particularly great importance in the treatment of sludge from sewage-treatment plants contaminated with heavy metals, in view of the gel structures of such sludge which are unstable in terms of soil mechanics, in order, after homogenizing them with said solid dispersion, to be able to dump them in the form of a material with a high bearing capacity which is stable from a soil-mechanical point of view. In this connection it is especially advantageous from an economic point of view to mix in suitable waste materials that have been contaminated witn heavy metals, for example slags and ashes.

According to one especially effective variant of the process, one portion of the clay is first kneaded with an aqueous alkali sulphide solution and a second clay portion with a finely dispersed aqueous suspension of iron sulphate. When the two portions are subsequently homogenized, this gives rise in situ to very finely dispersed iron sulfide embedded in the clay structure. The compound, which is still paste-like, is now chemically reacted with around 20%, based on the total amount of clay, normal calcium oxide, i.e. not rendered water-repellent. The stoichiometric ratios are chosen to give a slight excess of iron ions, e.g. 10%. The active compound now consists of iron sulfide, which is considered insoluble in water. However, the very much smaller solubility product of the sulfides of toxic heavy metals means that a precipitation occurs after mixing in materials contaminated with heavy metals. This allows a particularly effective method of immobilizing heavy metals without risk to the ground water through direct use of mobile, i.e. water-soluble, alkali sulfides.

In the aforementioned example and in the associated variant of the process, substances, like said iron sulfide, are employed that are readily recognizable as active compounds on account of their chemical reactivity, notably as a precipitating reagent.

However, the invention also allows substances regarded as chemically inert to be used as active substances.

For example, if hard bitumen is melted down and kneaded with clay, and this mix, once it has become homogeneous, is reacted with preferably hydrophobic calcium oxide and then kneaded again, after some time the water-consuming calcium oxide hydration reaction will take place, and the originally paste-like material disintegrates into a pulverulent solid dispersion charged homogeneously with hard bitumen. As is known, the calcium hydroxide contained in this solid dispersion is by no means inert chemically, but has highly basic properties and can therefore readily be reacted, e.g. with carbon dioxide, whereas the hard bitumen likewise contained in this solid dispersion is I x PCT/EP92/00436 completely inert from a chemical viewpoint.

However, the mixture of clay particles and calcium hydroxide present in the solid dispersion_ is the carrier and the hard bitumen the active compound if the object is, say, to render harmless, by a process of irreversible immobilization, highly toxic organic substances such as polychlorinated biphenyls (PCB) or dioxins and dibenzofurans (PCDD/PCDF), e.g. as substances contained in filter dusts from refuse incineration plants or as contamination in soils. To this end, such contaminated flue dusts or soils are mixed with a powdered solid dispersion charged with a hard bitumen and produced using clay and calcium oxide, and the mixture is compacted to produce a soil. After a short time the finely dispersed hard bitumen in the solid matrix has incorporated the harmful organic substances on account of their good solubility in the hard bitumen solid solvent. Leaching trials under long-term test conditions and applying trace analysis methods vouch for the fact that harmful organic substances treated in this way in accordance with the invention remain permanently and completely immobilized. Other high-boiling inert organic substances such as high melting point wax, vaseline or mineral oil may be used in place of the hard bitumen.

It is not possible to list the active compounds and mixtures thereof individually, because the choice thereof will automatically be decided on conventional criteria on the basis of the particular application envisaged. It is, for example, known that different concentrations and bioavailability of trace elements are needed when producing 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 ;aid plant trace elements are not uniformly available because they cannot be uniformly dispersed in the substrate. On the other hand, if the same compounds of the said trace elements are first kneaded into a clay matrix and uniformly distributed in this manner, after homogenizing this mixture with calcium oxide an extremely finely dispersed solid preparation is obtained in which the active ingredients are extremely uniformly dispersed. Simultaneously dispersing tartaric and citric acid provides a way of determining the bioavailability of said trace elements in advance. If the trace element compounds, with or without tartaric acid, are individually converted to a powdered solid dispersion and it is not desired to mix them in the particular proportions required for the application until later, it is also advisable to mix in a water repellent, for then no detrimental interactions are possible between the compounds of the trace elements within the mixture of the individual powdered solid dispersions.

In the same way is possible to process the most diverse types of plant nutrients, provided they are stable in the resulting alkaline medium, into extremely homogeneous slow-release fertilizers.

n3 PCT/EP92/00436 The number of active compounds that can be used in the field of environmental protection is too great to list, because the number of harmful substances leading to problems is so great.

Thus, in theory, for each harmful substance, or at least for each class of harmful substances, there are active compounds within the meaning of the invention that can be employed as reagents, e.g. as precipitating, condensing or addition agents, for immobilization and detoxification, to name but a few examples. In this connection high-boiling organic phases are of particularly great importance as active compounds for the adsorption or absorption of both harmful inorganic and organic substances, for this form of immobilization and physical fixation is especially straightf orward and thorough; one example among many is the absorptive removal of harmful substances from waste gases from refuse incineration plants with the help of long-chain amines as the active compound. Furthermore, still further active compounds may also be worked into the highboiling organic phase that have the ability to interact chemically with harmful substances and therefore shift the equilibrium position in favour of complete absorption, for instance by means of long-chain amines in a bituminous phase. Anyone skilled in the art will be familiar with the relationship between choice of active compounds and the object that is to be achieved, and this therefore requires no further explanation here; for instance, any person skilled in the art will be aware that finely dispersed metals such as magnesium or aluminium can be used to dehalogenate aromatic compounds containing halides.

In the second example cited further above, in which the use of hard bitumen as active compound is illustrated, hydrophobic calcium oxide is preferably employed. It is an essential aspect of the invention that the water contained in the finely dispersed suspension is consumed uniformly in the chemical reaction with alkaline earth oxide or aluminium alcoholate, because only on this condition can a homogeneously charged powdered solid dispersion be.produced. For this reason the water-consuming reaction must not begin until the alkaline earth oxide or aluminium alcoholate has been uniformly dispersed in the homogenized mix from the active compound and the suspension.

This can be achieved either by homogenizing the homogenized mix comprising aqueous, finely dispersed suspension and active compounds so quickly with the alkaline earth oxide or aluminium alcoholate that the latter are uniformly dispersed in the homogenized mix before the water-consuming chemical reaction has begun to any appreciable extent, or by adding conventional reaction retarders to the aqueous finely dispersed suspension, e.g. ammonia solution, alcohols, alkali sulphates and the like, or else by pre-treating the alkaline earth oxide or aluminium alcoholate in the corresponding manner, e.g. with alcohol or long-chain amines, fatty acids or the like.

In place of the pure alkaline earth oxides or aluminium alcoholates it is also possible to use mixtures of alkaline earth oxides or aluminium alcoholates or mixtures of both classes of S\ compounds.

PCT/EP92/00436 Where these pulverulent suspensions charged homogeneously with active compounds are to be used for agricultural or engineering applications, more particularly in the field of environmental protection, it is advantageous to set an excess amount of calcium oxide, preferably hydrophobic calcium oxide, by use of a suitable procedure or subsequent mixing. This allows cohesive contaminated materials to be so broken down in one operation that the active compounds are dispersed uniformly in the medium and all the harmful substances are intercepted and rendered harmless.

EXAMPLES

Example 1 100 parts by weight of a natural plastic clay are homogenized in a compounder with 18 parts by weight of a calcium oxide rendered hydrophobic with 1% fatty acid. The hydration reaction, which begins after about 5 minutes, takes place outside the compounder; the result is an extremely homogeneous solid dispersion of calcium hydroxide in clay, which is so homogeneous that the constituents are no longer visible even under a microscope.

Variant The plastic clay is first kneaded with 2% potassium sulfate as reaction retarder and then with calcium oxide that has not been rendered hydrophobic. The hydration reaction only begins after some 20 minutes have elapsed.

Variant In place of clay, red mud from the Bayer process is used, or a paste prepared from 70 parts by weight of dry, spent bleaching earth and 30 parts by weight of water.

Variant In place of calcium oxide, the stoichiometric equivalent of aluminium mixed alcoholate or silicic acid esters can be used; in these cases the alcohol released during hydrolysis evaporates; it can be recovered by condensation.

Example 2 parts by weight of clay, 7.6 parts by weight of iron sulfate FeSO4.7H20, 3 parts by weight of sodium sulfide Na2S and 4 parts by weight of water are homogenized in a compounder. The homogenized mix is homogenized with 15.4 parts by weight of calcium oxide. The result is 100 parts by weight of a pulverulent solid dispersion charged homogeneously with 2% iron sulfide FeS, which can be used to precipitate heavy metals in contaminated materials. The proportion of iron sulfate is chosen to give a 20% excess relative to the amount required stoichiomecrically; this prevents soluble alkali sulfide, for example in the treatment of contaminated soils or contaminated ,industrial wastes, from being able to pass into the ground PCT/EP92/00436 water in the course of treatment in accordance with the invention. The clay in this example can be replaced in full or in part by pastes mixed from dry, spent bleaching earth with water, for example 77 parts by weight of spent bleaching earth from the food industry with 23 parts by weight of water or with so-called red mud from the Bayer process, or else by mixing a fine-particle filter dust with enough water to produce a claylike matrix. It is not necessary to add reaction retarders in this example, for the iron sulfate, like the alkali sulfates, already retards the chemical reaction of t. calcium oxide such that complete homogenization is possible before the waterconsuming 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 positive mixer.

parts by weight of clay are homogenized with an aqueous solution of 3 parts by weight of sodium sulfide in 2 parts by weight of water in a positive mixer.

Once homogenization has taken place, the two portions are homogenized in a positive mixer and then the resulting homogenized mix homogenized with 15.4 parts by weight of hydrophobic calcium oxide. The result is a pulverulent solid dispersion charged extremely homogeneously with 2% iron sulfide FeS, and said dispersion can be employed in the same way as that of Example 2.

Example 4 In a variant of Examples 2 and 3, the separately produced homogeneous mixes of clay and iron sulfate, and of clay and sodium sulfide, respectively, are homogenized with 7.7 parts by weight of calcium oxide and hydrophobic calcium oxide, respectively. By mixing the two pulverulent solid dispersions charged homogeneously with iron hydroxide and sodium sulfide, respectively, a preparation is obtained which can be used particularly effectively and at the same time in an environmentally safe manner in the presence of excess hydrophobic calcium hydroxide to treat cohesive materials containing heavy metals.

This is because on the one hand precipitation of the heavy metals takes place immediately with the help of the alkali sulfide, but on the other hand no trace of this sulfide is able to pass into the environment because it is intercepted by the iron hydroxide that is present, without thereby cancelling the precipitating action on heavy metals not yet reached.

Example 56 parts by weight of clay are plasticized with 15 parts by weight of water and pre-heated to 70 0 C. This aqueous, finely dispersed suspension is homogenized in a compounder with parts by weight of melted bitumen B 80. The resulting homogene-

U

kZ PCT/EP92/00436 ous mix is then homogenized with 56 parts by weight of calcium oxide which has been rendered water-repellent with 1% fatty acid. The result is a pulverulent suspension homogeneously charged with bitumen which suspension can bd used in the field of environmental protection both to isolate and protect landfills and to immobilize non-ionic harmful inorganic and also organic substances. To this end, the suspension is mixed with a contaminated material, say in a ratio of 1:4, for example with a material containing halogenated dibenzodioxins or dibenzofurans in ppm range. The exact proportions required are determined by simple routine tests to ascertain the pure bitumen's capacity for adsorbing the type and quantity of harmful substance concerned. To absorb harmful substances with certain functional groups, the melted bitumen is for example mixed with the required amount of an active compound that contains a functional group capable of reacting with the harmful substance, thereby shifting the adsorption equilibrium towards a complete adsorption. To treat harmful substances thac cannot be immobilzed inside the alkaline range, rather than the calcium oxide a commercial mixed aluminium alcoholate is employed, e.g.

from aluminium isopropanolate and aluminium isobutanolate. The clay can at this point be replaced to particular advantage by red mud from the Bayer process, because this finely dispersed system is especially efficient in the dry state at adsorbing said dioxins and furans.

Example 6 150 parts by weight of clay with a 23% water content are plasticized with 10 parts by weight of water in a compounder and homogenized with 1 part by weight of a water-soluble salt of copper, manganese, z molybdenum, boron, and iron, respectively, e.g. in the form of the corresponding copper, iron, manganese and zinc sulfates, and respectively as ammonium molybdate and potassium metaborate. The resulting homogeneous mixes are then homogenized in a compounder with an alkaline earth mixture comprising 90% calcium oxide and 10% magnesium oxide, rendered water-repellent with 0.2% fatty acid. The individually obtained homogeneous pulverulent solid dispersions charged with the aforementioned trace elements are mixed in a vertical tube mixer in a required ratio corresponding to the envisaged application. The result is an additive for producing substrates for plants from peat or compost. The water-repellent properties of the additive bring about rapid mixing even with very moist peat or compost. The term mixing ratio corresponding to the envisaged application, as used here, denotes the different requirement which plants have in their various growth phases. Should an above-average increase in the bioavailability of the individual constituents be desired, the clay is homogenized in the corresponding preparation with an additional 1 part by weight of tartaric acid or, to still further increase the bioavailability, with 1 part by weight of citric acid.

Example 7 [7 i 100 parts by weight of clay or loam are plasticized with PCT/EP92/00436 parts by weight of water and homogenized with 20 parts by weight of calcium cyanamide; the resulting homogeneous mix is then homogenized with 10 parts by weight of hydrophobic calcium oxide. The solid dispersion thus obtained can be used af a nitrogenous agricultural slow-release fertilizer.

Example 8 In a combination of Examples 2 and 5, 100 parts by weight of clay are homogenized in turn 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 of melted bitumen in a positive mixer; the resulting homogeneous mix is then homogenized with 28 parts by weight of a calcium oxide rendered water-repellent with 0.5% fatty acid. The resulting pulverulent solid dispersion, charged homogeneously with the active compounds iron sulfide and bitumen, can be used for simultaneous irreversible immobilization of heavy metals and high-toxicity compounds, e.g. PCDD/DF in correspondingly contaminated filter dusts and ashes from refuse incineration plants.

Example 9 Respective double excesses of the stoichiometrical amounts of dipotassium hydrogen phosphate, iron sulfide and calcium carbonate are separately converted to homogeneous solid dispersions as in the method in Example 2, using calcium oxide that has been rendered water-repellent with 1% fatty acid. The mixture of the various solid dispersions is eminently suited to irreversibly immobilizing heavy metal ions in sewage sludge, composts, river and harbour sediments, by precipitating the individual heavy metals as carbonates, sulfides and phosphate-.

Arsenic and antimony can also be chemically fixed in this way.

To this end, said solid dispersions are mixed simultaneously with additional, slightly water-repellent calcium oxide into the waste matters that are to be treated, e.g. by feeding thpm synchronously into a vertical tube mixer. For the first 1-*.e this enables large quantities of these waste matters to z'e stored without further safety measures in an environmentally neutral fashion or used as landfill, e.g. for landscaping purposes. The necessary proportions are determined by the requirements of soil mechanics; they can be ascertained in conventional suitability tests, e.g. by determining Proctor density.

Example 100 parts by weight of clay, or a paste mixed from finely dispersed aluminium hydroxide or zeolith or bentonite with water, or spent, moist bleaching earth, or 100 parts by weight of a mixture of said suspensions, are homogenized in a compounder with 50 parts by weight of a long-chain amine, e.g.

stearylamine, and 10 parts by weight cf an aminosilane, e.g. a trialkoxyaminosilane, and then homogenized with 500 parts by weight of hydrophobic calcium oxide. The resulting dry, pul- Iv, -4 PCT/EP92/00436 verulent and homogeneous solid dispersion, containing excess calcium oxide, can be used as such or else, after the hydration reaction with not quite the stoichiometric amount of water in relation to the calcium oxide excess has hren carried out, in the form of this reaction product, i.e. icalcium hydroxide as the chief component in terms of quantiL for very extensive adsorption or chemisorption of harmful substances in the offgases of refuse incinerator plants, especially of halogenated dibenzodioxins and dibenzofurans.

Example 11 100 parts by weight, or a paste mixed from finely dispersed aluminium hydroxide or zeolith or bentonite with water, or spent, moist bleaching earth, or 100 parts by weight of a mixture of said suspensions, are homogenized in a compounder with 50 parts by weight of an alkali sulfide or alkaline earth sulfide and the resulting homogeneous mix then homogenized with 150 parts by weight of hydrophobic calcium oxide. Thanks to its hydrophobic nature, the resulting Iry, pulverulent and homogeneous solid dispersion, containing excess calcium oxide, can readily be worked into the surface of industrial waste tips containing heavy metals. This produces, over a large area, a deposit with precipitating reagents which, on account of slowacting desorption processes (sulfide ions) or else on account of their poor solubility (calcium hydroxide and calcium carbonate obtained from calcium hydroxide), are only incorporated very slowly into the tip along with rainwater as the vehicle, and there bring about precipitation reactions in situ. The absolute quantity of precipitating reagents required for this, and thus the thickness of the deposited layer, can be ascertained from the height of the tip and the average concentration of precipitable heavy metals in the tip. A similar procedure is adopted for immobilizing harmful substances in other accumulated deposits and waste dumps.

Claims (25)

1. Process for producing homogeneous, finely dispersed, pulveru- lent solid dispersions, consisting essentially of a) mechanically homogenizing an aqueous, finely dispersed suspen- sion with an alkaline earth oxide or an aluminium alcoholate or a silicic acid ester or with a mixture of these compounds, and b) allowing the alkaline earth oxide or the aluminium alcoholate or the silicic acid ester or the mixture of these compounds in the homogeneous mix to react with the stoichiometric quantity of water.

2. Process of claim 1 wherein said aqueous, finely dispersed sus- pension comprises a material of natural or industrial origin.

3. Process of claim 1 wherein said aqueous, finely dispersed sus- pension has been obtained from finely dispersed dry materials of natural or industrial origin through the addition of water.

4. Process according to claims 1 to 3 wherein said aqueous, finely dispersed suspension of natural origin comprises pulverulent natural clay, natural clay and clay-like or clay-containing ma- terialj.

Process according to claims 1 to 4 wherein said aqueous, finely dispersed suspension of industrial origin comprises production residues, such as used bleaching earth and red mud in the form of a residue of the Bayer Process.

6. Process according to one of claims 1 to 5 wherein calcium oxide is employed as the alkaline earth oxide.

7. Process according to one of claims 1 to 6 wherein the alkaline earth oxide has been pre-treated with reaction retarders.

8. Process according to claim 7 wherein the reaction retarder com- prises a hydrophobizing agent. £CT/EP92/00436

9. Process according to one of claims 1 to 8 wherein the reaction retarders are added to said aqueous, finely dispersed suspen- sion.

Process according to one of the foregoing claims wherein said aluminium alcoholate comprises a commercial liquid mix of alu- minium alcoholates.

11. Process according to one of the foregoing claims wherein said silicic acid ester comprises a commercial mix of silicic acid esters.

12. Process according to claim 1 for producing pulverulent solid dispersions, homogeneously charged with active compounds, con- sisting essentially of a) mechanically homogenizing an aqueous, finely dispersed sus- pension with active compounds, b) homogenizing the resulting homogenized mix with an alkaline earth oxide or an aluminium alcoholate or a silicic acid ester or with a mixture of these compounds, and c) allowing the alkaline earth oxide or the aluminium alcoholate or the silicic acid ester or the mixture of these compounds in the homogeneous mix to react with the stoichiometric quantity of water.

13. Process according to claim 12 wherein the active compounds are formed in situ within an aqueous finely dispersed suspension by mixing appropriate proportions of aqueous, finely dispersed suspensions mechanically homogenized with the stoichiometrical quantity of the corresponding chemical components of the active compounds to be formed.

14. Process according to on of the claims 12 and 13 wherein said active compounds comprise substances and mixes of substances utilizable in agriculture.

Process according to claim 14 wherein said substances and mixes of substances utilizable in agriculture comprise fertilizers and/or trace elements and/or plant protection agents or mixes thereof. pFCT/EP92/00436

16. Process according to on of the claims 12 and 13 wherein said active compounds comprise inorganic or organic reaction partners for the detoxification, imnmobilization and chemical fixation of harmful substances.

17. Process according to claim 16 wherein said active compounds comprise reducing metals like magnesium and aluminium or pre- cipitating agents like sulfides, carbonates and phosphates.

18. Process according to on of the claims 12 and 13 wherein said active compounds comprise inorganic and/or organic adsorption and absorption agents for the immobilization and adsorptive or absorptive fixation of harmful substances.

19. Process according to claim 18, wherein said inorganic and/or organic adsorption and absorption agents comprise high-boiling inert substances.

Process according to claim 19, wherein said high-boiling inert substances comprise paraffin wax, vaseline, bitumen and bitumi- nous substances.

21. Method for the improvement of agricultural and technical proc- esses consisting of employing said pulverulent finely dispersed solid dispersions produced according to one of the claims 1 to

22. Method for the improvement of agricultural and technical proc- esses consisting of employing said pulverulent finely dispersed solid dispersions produced according to one of the claims 1 to along with an excess of calcium oxide and/or aluminium alco- holate.

23. Method for the immobilization, fixation, insulation, encapsula- tion and detoxification of harmful substances consisting of em- ploying said pulverulent finely dispersed solid dispersions produced according to one of the claims 1 to

24. Method for the immobilization, fixation and detoxification of harmful substances in off-gases consisting of employing said pulverulent finely dispersed solid dispersions produced accord- ing to one of the claims 1 to Method for the dehalogenation of halogenated organics consist- ing of employing said pulverulent finely dispersed solid dis i\persions produced according to one of the claims 1 to i INTERNATIONAL SEARCH REPORT International Application No PCT/EP 92/00436 I. CLASSIFICATION OF SUBJECT MATTER (if several classification symbols apply, Indicate all) According to International Patent Classification (IPC) or to both National Classification and IPC Int. C 5 C05D 3/02; C05D 9/00; C02F 11/00; C05G 3/00 A62D 3/00 II. FIELDS SEARCHED Minimum Documentation Searched 7 Classification System Classification Symbols Int. Cl. C05D; C05G; A62D; C02F Documentation Searched other than Minimum Documentation to the Extent that such Documents are Included In the Fields Searched s Ill. DOCUMENTS CONSIDERED TO BE RELEVANT' Category Citation of Document, I with Indication, where appropriate, of the relevant passages 1 Relevant to Claim No. 1I X FR, A, 2319407 (BOLSING

25 February 1977 1-8,10, see claims 1,3-12,14,15 21 A see page 1, line 28 line 39 -11,12,22 see page 2, line 12 line see page 3, line 14 line 18 see page 3, line 32 page 5, line 9 X WO, A, 8802269 (BOLSING, 7 April 1988 1-9,12, see claims 1-13 16-21,23 A see page 4, line 32 page 6, line 3 10,11, see page 7, line 12 page 8, line 25 13,24 see examples 1,4 X DE, A,2533791 (BOLSING, 3 February 1977 1,12,15, see claims 21 A WO, A, 8802268 (BOLSING. 7 April 1988 1,12,25 see claims A DE, A, 204665 (POHL, ED.) 29 January 1907 1,12,14, see claims 15,21 Special categories of cited documents: 1o later document published after the International filing date document defining the general state of the art which is not or priority date and not in conflict with the application but duentde te oe ohe art which is not cited to understand the principle or theory und rlying the considered to be of particular relevance Invention earlier document but pubiished on or after the International document of particular relevance; the claimed invention filing date cannot be considered novel or cannot be considered to document which may throw doubts on priority claim(s) or involve an inventive step which is cited to establish the publication date of another document of particular relevance; the claimed Invention citation or other special reason (as specified) cannot be considered to involve an inventive step when the document referring to an oral disclosure, use, exhibition or document Is combined with one or more other such docu- other means ments, such combination being obvious to a person skilled document published prior to the international filing date but in the art. later than the priority date claimed document member of the same patent family IV. CERTIFICATION Date of the Actual Completion of the International Search Date of Mailing of this International Search Report 21 April .1992 (21.04.92) 20 May 1992 (20.05.92) International Searching Authority Signature of Authorized Officer European Patent Office Form PCT/ISA/210 (second sheet) (January 1985) ANNEX TO THE INTERNATIONAL SEARCH REPORT ON INTERNATIONAL PATIENT APPLICATION No. EP 9200436 SA 56667 Tis am.e fists the patent family members relating to the patent documents cited in the above-mentioned international search report- The members are as contained in the European Patent Office EDJP file on The European Patent Office is in no way liable for these particulars which are merely given for the purpose of information. 21/04192 Patent document Publication Patent family Publication cited in search report L date member(s) date FR-A-23 19407 25-02-77 DE-A- 2533789 03-02-77 AT-B- 359979 10-12-80 BE-A- 844618 16-11-76 CH-A- 621946 13-03-81 GB-A- 1563504 26-03-80 JP-C- 1478068 27-01-89 JP-A- 52021276 17-02-77 JP-B- 63015008 02-04-88 NL-A- 7608336 01-02-77 US-A- 4350598 21-09-82 US-A- 4488971 18-12-84 WO-A-8802269 07-04-88 OE-A- 3632365 3 1-03-88 EP-A,B 0326561 09-08-89 JP-T- 2500488 22-02-90 DE-A-2533791 03-02-77 None WO-A-8802268 07-04-88 DE-A- 3632363 31-03-88 EP-A,B 0324754 26-07-89 JP-T- 2500006 11-01-90 DE-A-204665 None 'W For more details about this annex :see Official Journal of the European Patent Office, No. 121S2 INTEJINATIONALER RECHERCHENBERICHT Intanationsfes Akteuz~cden PCT/EP 92/00436 1. "CASIFIKATION DES ANMEW.UNGSGEGENSTANDS (bei wehmwa- Ylasiftkitiocssymbolen si all. anzugjea)6 Nach der loternatigoclen Patentklassifktao (IPC) oder nach der natoalen Kiasslflkadof and der ]PC Int.K1. 5 C05D3/02; C0509/00; C02F11/00; C05G3/00 A62D3/00 H. RECHLROIIERTE SACHGEBETrE Redhercblerter MlndestpMllfsff 7 Mmfktionsrytem Maiiktonsrymbole Int.Kl. 5 C05D C05G ;A62D C02F Rechercblefle nidbt Dim Mlndestrlfstaff gdibrende Vetilffentichungen, somelt die. unter die redherdhienen Sachgeblete Malln

1101. EINSCHLAGIGE VEROFFENTLICHUNGEN I Art Keanzeiebnung icr Vertlffentliung t1 soweit erfordeich unter Anpabe der maflrbllcben Tell. 12 -7 Betr. Ansrucki N. 12 X FR,A,2 319 407 (BULSING 25. Februar 1977 1-8,10, 21 siehe AnsprUche 1,3-12,14,15 A siehe Seite 1, Zeile 28 Zeile 39 11,12,22 siehe Seite 2, Zeile 12 Zeile siehe Seite 3, Zeile 14 Zeile 18 siehe Seite 3, Zeile 32 Selte 5, Zeile 9 X WO,A,8 802 269 (BUSING, 7. April 1988 1-9,12, 16-21,23 siehe AnsprUche 1-13 A siehe Seite 4, Zeile 32 Seite 6, Zeile 3 10,11, 13,24 siehe Seite 7, Zelle 12 Seite 8, Zelle siehe Beispiele 1,4 X DE,A,2 533 791 (BbLSING, 3. Februar 1977 1,12,15, 21 1 siehe Anspr~che________ Bfesoodere Kategorien von angelebens Veroffentllcbun. ml e lgzle Stand der Tedhnlk Sj~ Veroffestlichunj i. ah dew Intetnatlocalen An- deflilrt, alar nthe1,beoo.derbedeutas anzuscen 1st meldedaturs oder ioam Froritltstum veroffentit warden MLteres Dokament, das fedoch ams aca oder nach demterne- Ist and tilt der Anatoldun 1 nldht kollidlert, sondern ourt Dim tionalen Anmededatum veofntih wode i Veusandmis des der Erfindung znrnolleooden Priazips W Ve~anicbug. ie gdfot Lt, enenPriowsa Mcboder der ibr zagpunollegenden neurle angegoben ist LTP 'IrVeoffondiang von baoodwor "&vtag dl. beanspiuch- feotllchansdw elneadro it. RedcrdbGnbetht go- to Erfindung kann nlit als non oder adf aflndetlader Meig fisonten Verffetlicbang bake warden soil odor diauiness kelt berubaid baradita warden anderen besonioten Grand angeeon ist (wic ansgefuhrt) "Y VetC'ffentllchang vga besoorer BDndoutn die beassrucb- 0' Vet~ftliiung, die sicli aid eine ulinilcho Offenbaning toeErfindung kan nlit aft aid eridrs rTjLtl e- eine Beontun. dun. Anwsteilung odet andero Mailahmen eie oe menrcron anderen Veofnlcugo irKte beziebt gone in Verbiung geixacht wind and these Ven dte Kate 'P Veaoffentllchung al vor dew Inteenasionslen Anxnelidad- anan Faduasan nahqilegad 1st turn, alter naat de beanspruchten Priorkliftdatutm verdt-fet W veo tuichug, die Nfitgiled derseben Pulentfazilio is? lidat warden int MV BESCREINIGUNG Datum des Abschlusses ier internatioamlen Racherche Absendociatum des internadonalen Rtachebakbacts 21.APRIL 1992 20 05.92 Internationale Recberchenbelabrde Untersdarift des bevollmichtlten Bedlenstten EUROPAISCHES PATENTAMT RODRIGUEZ FONTAO H. BI Paeiag PCTISAJ21O 1111W. 21 (Juser 192M) PCT/EP 92/00436 Intunatgnales AluenzeideL U1. ON'SCIAGIGE VEROFFENUICHUNGEN (Fortsetl~fg von Manl 2) An IvenzAichnang der V(?tffenfichufl, soveit erfotdeiIc flic ner Ampbe der MLaehlend Teie Btu. Awspnmch Nr. A WO,A,8 802 268 (BULSING, 7. April 1988 1,12,25 siehe Anspriiche A DE,A,204 665 (POHL, ED.) 29. Januar 1907 1,12,14, siehe AnsprUche152 A WORLD PATENTS INDEX LATEST 1,12,24 Week 8850, Derwent Publications Ltd., London, GB; AN 88-354759 DE,A,3 717 848 (RH WESTFAL KALKWERK RH WESTF ELECTRIZIrF AG) 8. Dezember 1988 siehe Zusammenfassung Fa,"21I PCTILW210I (Zmk1dxom 4jaw~ I9asl ANHANG ZUM INTERNATIONALEN RECHERCHENBERICHT O)BER DIE INTERNATIONALE PATENTANMELDUNG NR. EP 9200436 SA 56667 In dievmg Anbang dnd die Mtglieder der Pateatfamilen der im obengenanoten iaternationaica Rocbmenebericbt mngefithrtco Pateatdokumente angegebec. Die Angaben fiber die Farni enmitglieder entipeeben dean Stand der Datel dom Earopiischen Patentatats am Dime Angaben dienen nur zair Unterriebtung und erfolgen obne Ge; -Sr. 2 1/04/92 Im Rcberchezabericht Datmn der Mltglieder) der Danon der mngefirtes Patentdolwinent Vermenadicbing Patenafie Verbffendichung FR-'A-23 19407 25-02-77 DE-A- 2533789 03-02-77 AT-B- 359979 10-12-80 BE-A- 844618 16-11-76 CH-A- 621946 13-03-81 GB-A- 1563504 26-03-80 JP-C- 1478068 27-01-89 JP-A- 52021276 17-02-77 JP-B- 63015008 02-04-88 NL-A- 7608336 01-02-77 US-A- 4350598 21-09-82 US-A- 4488971 18-12-84 WO-A-8802269 07-04-88 DE-A-- 3632365 3 1-03-88 EP-A,B 0326561 09-08-89 JP-T- 2500488 22-02-90 DE-A-2533791 03-02-77 Keine WO-A-8802268 07-04-88 DE-A- 3632363 3 1-03-88 EP-A,B 0324754 26-07-89 JP-T- 2500006 11-01-90 DE-A-204665 Keirue Fuir nihere Einzelheiten zu diesesn Anliang: ebe Amtsbtu des Europiischen Patentamts, Nr.12/82