AT395706B - METHOD FOR INERTIZING AND / OR IMMOBILIZING INORGANIC AND / OR ORGANIC ENVIRONMENTALLY RELEVANT POLLUTANTS IN AQUEOUS WASTE MATERIALS - Google Patents

Abstract

A process is described for treating waste substances which contain organic and/or inorganic environmentally polluting compounds which is distinguished in that binders are added to the waste materials which are present in aqueous dispersion, suspension and/or solution, which waste materials have if appropriate been pretreated with materials for precipitation and/or conversion of the heavy metals, sulphur compounds and/or other pollutants present in them, and/or organic compounds and after the addition of these binders, and if appropriate after the addition of alkalis, slaked lime and/or setting time regulators, to compensate for losses of readily volatile components of the binder in the subsequent filtration operation by removal together with the press water, the water content is further decreased prior to the setting of the binder, preferably in a filter press, vacuum press, ram press, roller press, briquetting press or similar apparatuses.

Description

AT 395 706 B

The aim of the invention is to enable permanent, safe integration of pollutants by treating waste materials with hydraulic binders.

In the case of the wash water from flue gas cleaning systems or from sludges and similar aqueous dispersions, suspension »! or solutions in filter presses or similar dewatering devices · 5 the filter cakes are extraordinarily fine-grained material mixtures, which is suitable for the integration of

Pollutants in the filter cake prove to be cheap and improve them. After the filter press, these filter cakes often still have a water content of 50 to 70% or even higher. It has proven to be extremely difficult to mix these fine-particle, often plastic filter cakes with cement or other binders in such a way that there is a homogeneous distribution of the material forming the filter cake in the binder.However, these 10 non-digested waste particles represent weak points, since they bind the Deteriorate pollutants, can adversely affect hardening and can impair the durability of the shaped bodies or compact bodies formed from the binder-strengthened material. The miscibility with the binders is further complicated by textures that arise during the pressing process, which are similar to those that are formed when plastic clays are deformed in the ceramic industry. These textures increase the water content and thus impair the miscibility with the binder. Surprisingly, it has now been found that all of the above-mentioned difficulties which arise when mixing filter cake-forming material and binder by methods known in the art can be eliminated if, instead of the filter cake, the washing water or the sludge containing the waste material already before the pressing process is mixed with the binder, in particular the cement, 20 and the pressing process is then carried out after a waiting time due to the material, but before the binder has hardened. This prevents the formation of structures, as a result of which an optimal mixture of the material to be mixed and the binder is achieved, and the subsequent pressing process is essentially facilitated and accelerated. This procedure also increases the dry matter content of the filter cake. An advantage resulting from the greater reduction in the water content is the associated reduction in the chloride content of those filter cakes by increasing the removal of the contained »! Chloride with the press water, which significantly improves the strength of the molded body obtained in the pressing process and cemented with cement.

If, on the other hand, the binder is only mixed in after the filter cake has been pressed out, even a partially homogeneous mixture can only be achieved by adding considerable amounts additionally! Water, which naturally reduces the achievable strength and durability.

Mixing the aqueous dispersion, suspension and / or solution containing the waste materials with the binder prior to the pressing process also proves to be advantageous for an intended incorporation of the pollutants, since the hardening of the binder which begins and the surface products which harden it in the process the integration is improved, and the 35 denser structures resulting from the lower water content significantly reduce the diffusion of ions in the product obtained.

The aim of the present invention is therefore to use the above-mentioned, advantageous process step of mixing the waste materials present in aqueous dispersion, suspension and / or solution with the binder prior to the filtering process for permanent and safe disposal. 40 A process is therefore created for the inertization and / or immobilization of inorganic and / or organic pollutants relevant to the environment in aqueous waste material dispersions, suspensions, emulsions and / or solutions with the addition of binders, with the waste material dispersions, Suspensions, emulsions and / or solutions which, if necessary, are subjected to pre-treatment, simultaneous treatment or post-treatment for the precipitation and / or conversion of the sulfur, sulfur compounds, other pollutants and / or organic compounds they contain, at least an inorganic binder, in particular based on Portland cement clinker, alumina cement clinker and / or hydraulic lime, is added and in the dispersion, suspension, emulsion and / or solution, preferably by intensive stirring, a homogeneous mixture of the pollutant (s) with the ( the) binder (s) is brought about. This method is characterized in that, if necessary, after adding alkalis, 50 calcium hydroxide and / or solidification time regulators to compensate for losses of easily soluble portions of the binder in the subsequent filtering process by removal with the press water, but before the binder (s) has hardened , the water content of the homogeneous pollutant / binder mixture obtained, preferably by compressing in a press, is reduced.

In the process according to the invention, binders based on a pordand cement clinker, 55 a clay de-cementing agent and / or hydraulic lime are expediently used, preferably in an amount of 10 to 90%, in particular 20 to 60%, particularly preferably 30 to 50%, based on the sum of the dry mass of waste and binder. -2-

AT 395 706 B

In order to further increase the binding capacity for pollutants, in particular for heavy metals and / or organic compounds and / or disruptive ammonium compounds, in the process according to the invention, in addition to the binder, before, with or after the addition of the binder, but before the reduction in the water content Waste materials present in aqueous dispersion, suspension and / or solution are added which increase the binding capacity for these substances mentioned above. Fly ash, blast furnace slag, tress and / or structural minerals such as zeolites, in particular clinoptilolite, clays, bentonites, fine-grained silica, for example residues from the silicon industry or precipitated silica, are used in particular. Since the binding capacity of these materials depends, among other things, on their chemical nature and is very high, for example in the case of bentonites and zeolites, but is lower in the case of blast furnace slag, fly ash, blast furnace slag, trass and the like are preferably used in amounts of 3 to 60%, in particular 5 to 45 %, particularly preferably from 10 to 30%, based on the sum of the dry mass of waste, binder and additive, and the structural minerals, such as zeolites, in particular clinoptilolite, clays, bentonites, fine-grained silica, for example residues from the silicon industry or precipitated silica in quantities of over 0.5%, in particular over 1.5% and particularly preferably over 3%, based on the sum of the dry mass of waste material, binder and additive

To further increase the binding capacity, inorganic and / or organic ion exchange, for example based on polystyrene-vinyl resins, in anemic or cationic form in amounts of 0.5 to 10%, based on the hydraulic binder, can advantageously be added in the process according to the invention.

It has proven to be particularly advantageous that in the waste materials present in the aqueous dispersion, suspension and / or solution, the hardening of the hardening of the hydraulic binders added for solidification are converted into harmless calcium compounds. This conversion into harmless calcium compounds is expediently carried out by adding calcium nitrate, calcium chloride, calcium oxide and / or calcium hydroxide, advantageously 1 to 30%, in particular 1 to 20%, particularly preferably 1 to 10%, based on dry waste and calculated as CaO, be added.

By converting it into harmless calcium compounds, uniform, targeted strengths can be achieved. In many cases, especially when the waste content contains organic components, this also results in a substantial reduction in the water content, which leads to correspondingly higher strengths

The precipitation of mercury compounds and / or other heavy-duty compounds in the form of insoluble sulfides known from the art can also be used in the present process. For this purpose, alkali and / or alkaline earth metal sulfides, in particular calcium sulfide, and / or organosulfides can be added to the aqueous dispersion, suspension and / or solution, or the aqueous dispersion, suspension and / or solution can be treated with hydrogen sulfide, the sulfide addition advantageously being 0. 01 to 5%, in particular 0.05 to 1%, based on dry waste and indicated as S, is.

In order to precipitate sulfur compounds contained in the aqueous dispersion, suspension and / or solution in the form of harmless ettringite, in addition to the binder, metallic aluminum powder and / or aluminum compounds, in particular sodium aluminate, if necessary in combination with, may be added to the binder Defoaming, added. With waste »! With a particularly high content of sulfur compounds, up to 35% aluminum or a corresponding amount of aluminum compounds and / or alumina cement, particularly preferably 1 to 10% aluminum or aluminum compounds and / or alumina cement, are expediently added. This early forced ettiingite formation prevents the binder from being driven later.

In order to improve the filtering behavior of the waste materials present in the aqueous dispersion, suspension and / or solution, the above-mentioned waste material can expediently be added to the binder before, with or after the addition of the binder, but before the water content is reduced, in the process according to the invention! Materials are added which improve the filtering behavior, in particular anionic, cationic or neutral-effect flocculants, minerals, such as, for example, burnt or slaked lime, sand, blast furnace slag and the like and / or fibers.

To increase the tightness, in addition to the binder, surface-active agents and / or plastics can be added before, with or after the addition of the binder, for which purpose water repellents, such as oleates, stearates, palmitates, silicones, silanes and the like, and also defoamers and the like in Migen from 0.05 to 5%, preferably 0.5 to 1%, or plastic dispersions based on homopolymers, copolymers or terpolymers, for example vinyl acetate polymers. Styrene-butadiene copolymers. Styrene-acrylates, in amounts of 0.1 to 15 %, preferably 1 to 5%, each related »! can be added to the amount of hydraulic binder. Among others To increase the tightness, polymer-forming substances, for example epoxy resins, can also be added in amounts of 0.1 to 10%, preferably 1 to 5%. The plastics used must be compatible with the cement, in particular alkali-stable. -3-

AT 395 706 B

For waste materials with high levels of sulfur compounds, a further increase in safety and improvement in hardening is achieved by using cements and / or hydraulic limes that do not contain sulfate solidification regulators (dihydrate gypsum, hemihydrate gypsum and / or anhydrite) or only one The usual proportions of the sulfate solidification regulator are greatly reduced. 5 Easily soluble substances present in the binder, e.g. As alkalis, raw gypsum stone, can go into solution during mixing with, for example, the washing water or sludge and can be carried out in the subsequent filtering or pressing process with the press water, which leads to a deterioration in the hardening or the strength of the molded or compact body subsequently produced It may be expedient to add additional amounts of these easily soluble substances, if necessary, before the hardening of the binder to compensate for the above-mentioned losses and / or to use binders which do not contain these slightly soluble substances or in smaller amounts. For this reason, it is preferable to use binders e.g. B. cements, which contain anhydrite as a solidification regulator instead of raw gypsum stone, or ground Portland cement clinker, alumina cement clinker and / or hydraulic lime without further additions of Erstamingsreglem. IS can also be used to avoid driving reactions to waste materials with reactive

Sulfur compounds, cements and / or hydraulic limes with a calcium aluminate content of less than 3.5%, in particular less than 3.0%, particularly preferably 0%, calculated according to Bogue, can be added.

Although heavy metals are generally well incorporated into cements, they are particularly well incorporated into cements or limes that form a lot of ettringite, i.e. H. which contain a lot of aluminate or aluminate ferrite. 20 Cements such as PSZ 400 with a content of 12 CaOJA ^ C ^ C ^ are particularly suitable. When these cements are used, an addition of alkalis, such as sodium carbonate, can be expedient in order to avoid hardening disorders, for example due to the readily soluble calcium compounds present as a result of the pretreatment of the waste materials. Cements or limes with high levels of aluminates or aluminate ferrite also include cements or limes with high levels of fly ash or blast furnace slag. In this case the aluminates / 25 aluminate ferrites originate from these additives. Combinations of these additives with appropriate cements, such as PSZ 400, are particularly suitable. A direct addition of ettringite can also be expedient.

An advantageous embodiment of the invention therefore provides for the use of a cement with over 5%, preferably over 10% and particularly preferably over 15% 12 CaOJA ^ Oj or 11 CaO.7Al2O3.CaF2. The abovementioned reduction in the calcium concentration in the liquid phase can be achieved by adding alkali compounds, in particular alkali carbonates, preferably in an amount of 0.1 to 5%.

Since the solubility of pollutants incorporated in the cement is strongly dependent on the pH value - at low pH values the solubility is ten orders of magnitude higher. In the long term, ensuring a high pH value is of particular interest. This permanent maintenance of a high pH value can be achieved by adding an alkali depot, in particular in the form of alkali and / or alkaline earth compounds, in particular of coarse-grained Portland cement clinker, hardened cement stone, gas concrete, asbestos cement, hard-fired

Lime or dolomite or semi-burned dolomite, blast furnace slag, fly ash and / or alkali hydroxide. Depending on the application of the alkali depot, a very different additional amount may prove necessary, so that the alkali depot is expediently added in amounts of 1 to 75%, based on the sum of dry waste material and hydraulic binder. 40 heavy metals are directly integrated into the cement stone phases during the consolidation with cement and are fixed there. Even in very favorable conditions with regard to the spatial stability and the tightness of the structure, it can occur in individual cases that small portions of the heavy metals are not optimally fixed and can therefore be mobilized (e.g. mercury). Through the addition of selectively binding materials, an additional elution camera is built that firmly binds any mobile pollutants that are released. This effect 45 is also supported by a sufficient alkali deposit and ensured in the long term.

By using the method according to the invention, it is possible to reduce the water content to such an extent that waste materials mixed with binder can be converted into moldings, if appropriate after adding further amounts of binder. It is therefore possible, immediately after the pressing process, to process the filter cakes in a further press or an extruder and the like to give shaped bodies, 50 of which are transferred to shaped bodies under the action of pressure and / or temperature, a mechanical pressure of over 3, in particular over 6, particularly preferably over 15 and in particular over 40 bar is used.

Furthermore, it has also proven to be advantageous to coat the moldings according to the invention with an inert protective layer consisting of mineral substances, for example water glass solution or organic substances, for example based on acrylate, styrene butadiene, vinyl copolymer or mixtures, for example plastic-modified 55 hydraulic compositions.

The moldings thus obtained in the process according to the invention can at most also be used as building blocks or the like. However, the filter cake obtained in the pressing device can be allowed to harden without further processing and can be deposited without any adverse effects on the environment. -4-

AT 395 706 B

The mixtures produced by the process according to the invention can also advantageously be shaped into granules, aggregates or concrete aggregates.

The advantageous properties of the moldings obtained by using the process according to the invention, in particular the strengths which can be achieved thereby, are explained in more detail in the example below, which is not intended to restrict the invention.

Example:

A wastewater from the flue gas scrubber of a waste incineration plant was mixed with lime hydrate, ferric chloride solution and reagents to precipitate the heavy metals in the usual way and the resulting sludge was pressed on a filter press at a dry matter content of 3.9%. The resulting filter cake had a dry matter content of 35%. and was then mixed with Portland cement PZ 275 (H) in a compulsory mix in a ratio of 1: 2, based on the dry state, in order to achieve an adequate distribution of cement and filter cake, 50% water had to be added again. Concrete cubes were made from the filter cake / cement / water mixture produced in this way (procedure according to the state of the art).

In a second test series, the same amount of Portland cement was added to the sludge according to the invention before the filter press. Due to the high water content of the sludge at this stage, the waste and cement could be mixed by simply stirring the sludge for 3 minutes. The waste / cement mixture was then fed to the filter press. The filter cake obtained had a dry matter content of 55%. It was stamped into concrete cubes without any additional water or cement.

The strengths achieved on the concrete cubes produced in this way are shown in Table 1. As can be seen from this, the addition of the cement according to the invention even before the reduction in the water content in the filter press decisively improved the development of strength. It was also noteworthy that the filtering time in 25 of the feed press when the binder was added before the filter press decreased to a quarter of the usual duration and that As mentioned, the dry matter content of the filter cake has increased from 35 to 55%

In further experiments, the mixing ratio “filter cake waste 1 to cement” was then changed. It was found that the addition amount necessary for solidification could be chosen significantly lower by adding the binder according to the invention before the filter press. 30 Even better results were obtained with alumina cement as a binder.

Table 1 35

Binder addition after the filter filter press in front of the mixing ratio of binder: waste material (based on dry mass of both) Compressive strength (N / mm ^) after n days 1 7 28 120 X 2: 1 n. E. 0.8 1.5 2.9 X 2: 1 2.2 3.8 6.3 103 X 0.9: 1 1.0 2.1 33 43 X 0.2: 1 0.2 1.0 1 , 6 2.7 X 0.4: 1 3.4 3.9 5.0 - (clay cement) 40 45 50 ne = not demouldable -5- 55

Claims (26)

AT 395 706 B PATENT CLAIMS 1. Process for the inertization and / or immobilization of inorganic and / or organic environmentally relevant pollutants in aqueous waste material dispersions, suspensions, emulsions and / or solutions with the addition of binders. Dispersions, suspensions, emulsions and / or solutions, which are optionally subjected to a pretreatment, simultaneous treatment or aftertreatment for the precipitation and / or conversion of the heavy metals, sulfur compounds, other pollutants and / or organic compounds contained therein, at least one inorganic binder , in particular based on Portland cement clinker, alumina cement clinker and / or hydraulic lime, is added and in the dispersion, suspension, emulsion and / or solution, preferably by intensive stirring, a homogeneous mixture of the pollutant (s) with the binder (s) ) is brought about, characterized in that d ate if necessary after adding alkalis, hydrated lime and / or Erstamingszeitreglem to compensate for losses of easily soluble parts of the binder in the subsequent filtering process by removal with the press water, but before the binder (s) has hardened, the water content of the homogeneous obtained Pollutant / binder mixture, preferably by compressing in a »press, is reduced. 2. The method according to claim 1, characterized in that at least one binder based on Portland cement clinker, alumina cement clinker and / or hydraulic lime in an amount of 10 to 90%, in particular from 20 to 60%, particularly preferably from 30 to 50%, based on the sum of the dry mass of waste and binder, is added. 3. The method according to claim 1 or 2, characterized in that in addition to the binder before, with or after the addition of the binder, but still before the reduction of the water content, the waste materials present in aqueous dispersion, suspension and / or solution are added materials which the Increase binding capacity for pollutants, in particular for heavy metals and / or organic substances, such as hydrocarbons, and / or disruptive ammonium compounds, in particular fly ash, blast furnace slag, trass, and the like, preferably in amounts of 3 to 60%, in particular 5 to 45%, particularly preferably from 10 to 30%, based on the sum of the dry mass of waste material, binder and additive, and / or structural minerals, such as zeolites, in particular clinoptilolite, clays, bentonites, fine-grained silica, for example residues from the silicon industry or precipitated silica in amounts of over 0 , 5%, especially over 1.5% and particularly preferably over 3%, based on the sum of the dry mass of waste material, binder and additive. 4. The method according to any one of claims 1 to 3, characterized in that to further increase the binding capacity of pollutants, in particular heavy metals and / or organic substances, such as hydrocarbons and / or disruptive ammonium compounds in addition to the binder, with or after the addition of the binder, inorganic and / or organic ion exchangers, for example based on polystyrene-vinyl resins, in anionic or cationic form, in amounts of 0.5 to 10%, based on the hydraulic binder, are added. 5. The method according to any one of claims 1 to 4, characterized in that contained in aqueous dispersion, suspension and / or solution waste materials, the hardening of the added to the solidification of hydraulic binders compounds before, with or after the addition of the binder by adding Calcium nitrate, chloride, oxide and / or hydroxide and / or other soluble calcium compounds can be converted into harmless calcium compounds. 6. The method according to claim 5, characterized in that 1 to 30%, in particular 1 to 20%, particularly preferably 1 to 10%, based on dry waste, calcium compounds, indicated as CaO, are added. -6- AT395706B 7. The method according to any one of claims 1 to 6, characterized in that for the precipitation of sulfur compounds in the form of harmless ettringite additionally binders before, with or after the addition of the binder metallic aluminum powder and / or aluminum compounds, especially sodium aluminate, if necessary in combination with Defoaming, added. 8. The method according to claim 7, characterized in that present in aqueous dispersion, suspension and / or solution «! Waste materials with a particularly high content of sulfur compounds up to 35% aluminum or an amount of aluminum compounds and / or alumina cement corresponding to this amount of aluminum can be added, based on dry waste material. 9. The method according to claim 8, characterized in that in aqueous »dispersion, suspension and / or solution waste materials with a particularly high content of sulfur compounds 1 to 10% aluminum or an amount of aluminum compounds corresponding to this amount of aluminum and / or alumina cement are added , based on dry waste. 10. The method according to any one of claims 1 to 9, characterized in that in addition to the binder before, with or after the addition of the binder, but still before the reduction in the water content, the waste material present in aqueous dispersion, suspension and / or solution « ! Filter aids are added, in particular anionic, cationic or neutral flocculants, minerals, such as, for example, burnt or slaked lime, sand, blast furnace slag and the like, and / or fibers. 11. Move «! according to one of claims 1 to 10, characterized in that in addition to the binder before, with or after the addition of the binder, but still before the reduction of the water content, the waste materials present in aqueous dispersion, suspension and / or solution to increase the Waterproofing surfactants and / or plastics are added. 12. The method according to claim 11, characterized in that hydrophobicizing agents, such as oleates, stearates, palmitates, silicones and / or silanes and the like and / or defoamers and the like, in a proportion of 0.05 to 5%, preferably 0.5 to 1%, based on dry waste. 13. The method according to claim 11, characterized in that plastic dispersions based on homopolymer, copolymer or Teipolym «, for example vinyl acetate polymers, styrene-butadiene copolymers, Sfyrolaciylate, in amounts of 0.1 to 15%, preferably 1 to 5 %, are added, based on dry waste. 14. The method according to claim 11, characterized in that polymer-forming substances, for example epoxy resins, are added in amounts of 0.1 to 10%, preferably 1 to 5%, based on dry waste. 15. The method according to any one of claims 1 to 14, characterized in that cements and / or hydraulic limes are used for the harmless incorporation of reactive sulfur compounds present in the waste materials present in aqueous dispersion, suspension and / or solution, which do not contain any sulfate solidification rules. (Dihydrate gypsum, hemihydrate gypsum and / or anhydrite) contain or only a proportion of solidification regulator which is greatly reduced in comparison with usual conditions. 16. The method according to any one of claims 1 to 15, characterized in that for compensation or to prevent losses of easily soluble portions of the binder during the filtering process by removal with the press water as a binder, cements and / or hydraulic limes which contain anhydrite as a sulfate solidification regulator, and / or ground Portland cement clinker and / or alumina cement clinker are used, and / or such substances are added before the binder has hardened. 17. The method according to any one of claims 1 to 16, characterized in that to avoid driving reactions in the case of waste materials with reactive sulfur compounds, cements and / or hydraulic limes with a calcium aliminates content of less than 3.5%, in particular less than 3.0%, particularly preferably from 0%, calculated according to Bogue. 18. The method according to any one of claims 1 to 17, characterized in that a cement with over 5%, preferably over 10% and particularly preferably over 15% 12Ca0.7Al203 or HCaO.7Al2O3.CaF2 is used as the cement. -7- AT 395 706 B Process according to one of claims 1 to 18, characterized in that to reduce the calcium ion concentration of the liquid phase, alkali compounds, in particular alkali carbonates, preferably in an amount of 0.1 to 5%, are added. 20. The method according to any one of claims 1 to 19, characterized in that an alkali depot is added to permanently maintain a high pH, in particular in the form of alkali and / or alkaline earth compounds, in particular of coarse-grained Portland cement cement, hardened cement stone, gas concrete, asbestos cement , hard-burned lime or dolomite or half-burned dolomite, blast furnace slag, fly ash, and / or alkali hydroxide. 21. The method according to claim 20, characterized in that the alkali depot is added in amounts of 1 to 75%, based on the sum of dry waste and hydraulic binder. 22. The method according to any one of claims 1 to 21, characterized in that the water content is reduced to such an extent that the waste materials mixed with binder can optionally be converted into moldings after the addition of further amounts of binder. 23. The method according to any one of claims 1 to 22, characterized in that the mixture is transferred into moldings under pressure and / or temperature 24. The method according to claim 23, characterized in that the production of the molded body follows under a mechanical pressure of over 3, in particular over 6, particularly preferably over 15 and in particular over 40 bar 25. The method according to any one of claims 22 to 24, characterized in that the moldings with an inert protective layer consisting of mineral substances, for example water glass solution, or organic substances, for example based on acrylate, styrene-butadiene, vinyl copolymer, or mixtures, for example plastic-modified hydraulic masses to be coated. 26. The method according to any one of claims 1 to 25, characterized in that the mixtures are deformed into granules, aggregates or concrete aggregates. -8th-