DE102022128972A1 - Process for preparing a pourable, flowable or pasty starting substrate and device for carrying out the process - Google Patents

Abstract

The method according to the invention for processing a starting substrate containing at least one solid and at least one high-boiling hydrocarbon comprises the steps of: adding a liquid extractant (B) to the starting substrate (A, A') in a mixing stage (3); homogenizing the starting substrate-extractant mixture in a homogenization stage (5); dividing the starting substrate-extractant mixture (C) withdrawn from the homogenization stage (5) in a solids separation stage (8) into a solids fraction (E) containing predominantly solids and a liquid fraction (F) containing predominantly liquid; batchwise division of the solids fraction (E) by means of vacuum evaporation (9) into a solids residue (G) and a vapor fraction (H); isolating the extractant from the liquid fraction (F) in a thermal separation stage (11) to form a hydrocarbon-containing residue (K); Returning the extractant isolated in the thermal separation stage (11) together with extractant recovered from the vapor fraction (H) resulting from the vacuum evaporation (9) for renewed addition to the starting substrate (A, A`); separate discharge of the hydrocarbon-containing residue (K) and the solid residue (G) from the processing plant.

Description

The present invention relates to a method for preparing a pourable, flowable or pasty starting substrate containing at least one solid and at least one high-boiling hydrocarbon. The invention further relates to a device for carrying out the method.

Solids in the sense of the present invention are all substances whose softening point at ambient pressure is above 500°C. And high-boiling hydrocarbons in the sense of the present invention are all hydrocarbons whose boiling point at ambient pressure is above 300°C. All other hydrocarbons are considered to be low-boiling in the sense of the present invention.

In various industrial processes, mixtures of substances are produced which contain at least one solid and at least one high-boiling hydrocarbon within the meaning of the present invention. A typical example of this is metal chips and/or other metal particles which are contaminated with cutting oil and which arise in metal processing, whereby corresponding mixtures of substances have a pasty or sludge-like consistency in the case of fine metal particles, such as those which arise in particular when grinding metal workpieces. Contaminated soils, namely sands contaminated with crude oil, can also be considered a typical example of a mixture of substances containing at least one solid and at least one high-boiling hydrocarbon within the meaning of the present invention, since crude oil typically contains, among other things, high-boiling hydrocarbons within the meaning of the present invention. Yet another typical example of a mixture of substances containing at least one solid and at least one high-boiling hydrocarbon within the meaning of the present invention are products containing mineral fibers and bitumen (e.g. in the form of a mineral fiber fleece impregnated with bitumen); Such mixtures of substances, which are pourable within the meaning of the invention at least after appropriate (mechanical) comminution, arise in large quantities, either as production waste or at the end of the intended service life of the product in question.

If, as is often the case, there is no immediate use for the mixtures of substances in question, they are mostly either deposited in landfills or disposed of in a waste incineration plant. In many respects, both are incompatible with the increasingly strict requirements and objectives with regard to sustainability, climate neutrality, energy efficiency, circular economy, etc.

Thus, the present invention is directed to providing a treatment of the said substance mixtures which is improved in the above respects compared to the prior art.

• - das schüttfähige, fließfähige oder pastöse, mindestens einen Feststoff und mindestens einen hochsiedenden Kohlenwasserstoff enthaltende Ausgangssubstrat wird in einer Mischstufe mit einem flüssigen Extraktionsmittel versetzt, in welchem der mindestens eine in dem Ausgangssubstrat enthaltene hochsiedende Kohlenwasserstoff lösbar ist;
• - das Ausgangssubstrat-Extraktionsmittel-Gemisch wird in einer Homogenisierungsstufe einer aktiven Durchmischung unterzogen;
• - aus der Homogenisierungsstufe abgezogenes homogenisiertes Ausgangssubstrat-Extraktionsmittel-Gemisch wird einer mechanischen Feststoffabscheidung unterzogen unter Aufteilung in eine überwiegend Feststoffe enthaltende Feststofffraktion und eine überwiegend Flüssigkeit enthaltende Flüssigkeitsfraktion;
• - die aus der mechanischen Feststoffabscheidung hervorgehende Feststofffraktion wird chargenweise einer Vakuumverdampfung unterzogen unter Aufteilung in einen Feststoff-Rückstand und eine Dampffraktion;
• - aus der aus der mechanischen Feststoffabscheidung hervorgehenden Flüssigkeitsfraktion wird in einer thermischen Trennstufe das Extraktionsmittel isoliert unter Bildung eines kohlenwasserstoffhaltigen Rückstands, in welchem die hochsiedenden Kohlenwasserstoffe angereichert sind;
• - das in der thermischen Trennstufe isolierte Extraktionsmittel wird zusammen mit Extraktionsmittel, welches aus der aus der Vakuumverdampfung hervorgehenden Dampffraktion zurückgewonnen wird, zur erneuten Zugabe zu Ausgangssubstrat rückgeführt;
• - der aus der thermischen Trennstufe hervorgehende kohlenwasserstoffhaltige Rückstand und der aus der Vakuumverdampfung hervorgehende Feststoff-Rückstand werden getrennt voneinander aus der Aufbereitungsanlage ausgeschleust.

The present object is achieved according to the present invention by a method for preparing a pourable, flowable or pasty starting substrate containing at least one solid and at least one high-boiling hydrocarbon, comprising the following steps:

• - the pourable, flowable or pasty starting substrate containing at least one solid and at least one high-boiling hydrocarbon is mixed in a mixing stage with a liquid extraction agent in which the at least one high-boiling hydrocarbon contained in the starting substrate is soluble;
• - the starting substrate-extractant mixture is subjected to active mixing in a homogenisation stage;
• - the homogenised starting substrate-extractant mixture withdrawn from the homogenisation stage is subjected to mechanical solids separation by division into a solids fraction containing predominantly solids and a liquid fraction containing predominantly liquid;
• - the solid fraction resulting from the mechanical solid separation is subjected to vacuum evaporation in batches and divided into a solid residue and a vapour fraction;
• - the extraction agent is isolated from the liquid fraction resulting from the mechanical separation of solids in a thermal separation stage to form a hydrocarbon-containing residue in which the high-boiling hydrocarbons are enriched;
• - the extractant isolated in the thermal separation stage is recycled together with extractant recovered from the vapor fraction resulting from vacuum evaporation for re-addition to the starting substrate;
• - the hydrocarbon-containing residue resulting from the thermal separation stage and the solid residue resulting from the vacuum evaporation are discharged separately from the processing plant.

Through the synergistic interaction of the various treatment steps, which are carried out in a defined sequence one after the other or in parallel to one another, it is surprisingly easy to break down the mixture of substances forming the starting substrate into fractions of comparatively high purity, so that material recycling is not only possible, but - depending on the substances contained in the starting substrate - even economically profitable, not to mention the ecological advantages resulting from the avoidance of waste or the inerting of problem substances. The high energy efficiency of the process according to the invention benefits, among other things, from the synergistic effects that can be achieved by the combination - applied to the starting substrate mixed with a liquid extractant - of treating the solid fraction resulting from mechanical solid separation by means of vacuum evaporation, isolating the extractant from the liquid fraction resulting from mechanical solid separation in a thermal separation stage, and returning the extractant isolated in the thermal separation stage together with extractant recovered from the vapor fraction resulting from vacuum evaporation for re-addition to the starting substrate. In this functional interaction, the special qualities of vacuum evaporation, namely the evaporation of volatile components at temperatures substantially reduced compared to ambient pressure, come into their own.

The comparatively low temperatures in the various components of the processing plant designed to carry out the method according to the invention lead to a correspondingly low heat and thus energy requirement. In addition, the heat required - particularly for vacuum evaporation (e.g. at an operating pressure of 0.05 bar at a temperature level of up to 350°C) - can be provided and transferred in an energetically attractive way, e.g. by indirectly heating the starting substrate mixed with extractant in the vacuum evaporation stage using an electrically heated thermal oil. The advantages mentioned apply in particular to the separation of extractants under vacuum evaporation at very low temperatures, for example at only about 100°C. Here, even renewable energy sources are well suited for heating the vacuum evaporation stage.

Since the material usability (including the achievable utilization proceeds) depends on the purity of the material flows discharged from the processing plant, namely the solid residue and the hydrocarbon-containing residue in which the high-boiling hydrocarbons are enriched, this influences the economic efficiency of the processing method according to the invention, as does the material value of the at least one solid contained in the starting substrate and the at least one high-boiling hydrocarbon contained in the starting substrate. And it is precisely with regard to the purity of the material flows discharged from the processing plant that the processing method according to the invention shows outstanding advantages, namely because the relevant parameters of the various treatment steps and stages can be excellently adapted to the respective starting substrate and its individual composition. This also includes the fact that, in the case of starting substrates which contain several different high-boiling hydrocarbons, a multi-stage thermal separation stage or a cascade of several thermal separation processes (individually tailored to the individual high-boiling hydrocarbons) can be provided in order to promote the recovery of hydrocarbons which are as pure as possible.

Which extraction agent is used - circulated in the process according to the invention - depends on the type of high-boiling hydrocarbon. Organic solvents (e.g. toluene) are very suitable for various high-boiling hydrocarbons. But organic acids (e.g. citric acid) can also lead to very good results in individual cases, possibly even better than organic solvents. If the starting substrate contains several different high-boiling hydrocarbons, extraction agent mixtures specifically adapted to these can also prove to be very suitable.

The present invention, as also expressed in the explanations below, provides a complete and closed solution for the separation of high-boiling hydrocarbons from mineral or metallic solids. The main, decisive advantages are that no additional, undefined processing steps are required and that there is a clear distinction from processing methods based on pyrolysis technology. The present invention is therefore also suitable for hazardous waste - unlike pyrolysis-based processing technologies. For safety reasons, pyrolysis technology can only be justified or used for non-hazardous, defined waste streams - at least in countries or regions with high safety standards such as Europe. Natural wastes with typically significant physical and/or chemical fluctuations in their composition can lead to the formation of unknown pyrolysis gases in pyrolysis reactors, which may have fatal consequences.

According to a first preferred development of the invention, the starting substrate is subjected to comminution before the addition of the extraction agent. In this way, the residence or treatment times in the various subsequent treatment stages can be kept comparatively short, which promotes high efficiency.

Another preferred development of the method according to the invention is characterized in that the addition of the liquid extractant to the starting substrate and the active mixing of the starting substrate-extractant mixture take place in a uniform mixing reactor that combines the mixing stage and the homogenization stage. In this way, the structural complexity of the processing plant can be reduced compared to plants with structurally separate mixing and homogenization stages.

According to yet another preferred development of the method according to the invention, the homogenized starting substrate-extraction agent mixture remains in a storage container before the mechanical solid separation.

In this way, not only can particularly good results be achieved in the subsequent removal of high-boiling hydrocarbons from the starting substrate-extraction agent mixture. Moreover, allowing the homogenized starting substrate-extraction agent mixture to remain in a container prepared for this purpose (intermediate storage) also has a positive effect due to the buffer effect. This is particularly true in view of the fact that in the process according to the invention one of the subsequent treatments, namely vacuum evaporation, takes place in batch operation.

As far as mechanical solids separation is concerned, various suitable methods and system components are available for this within the scope of the present invention. For various typical applications of the present invention, mechanical solids separation using a filter press or a screw press delivers very good results. Another very suitable system component for mechanical solids separation is a decanter. Particularly good results can be achieved with multi-stage mechanical solids separation, whereby two different technologies for mechanical solids separation can also be combined with one another if necessary.

Yet another preferred development of the invention is characterized in that the isolation of the extraction agent in order to be able to recycle it takes place in a multi-stage thermal separation stage. The advantages of such a multi-stage thermal separation stage are particularly evident when the liquid fraction resulting from the mechanical solid separation contains not only two components, namely the extraction agent and the high-boiling hydrocarbon extracted with it, but at least three components, for example also water. The multi-stage design of the thermal separation stage allows it to be adapted very specifically to the individually different composition of the liquid fraction resulting from the mechanical solid separation. This is conducive to a high degree of selectivity of the thermal separation stage in the sense of a high degree of purity of the material flows withdrawn from the processing plant, which in turn has a very positive effect on the economic efficiency of the process according to the invention or the processing according to the invention of the starting substrate in question for the material utilization of its components. In particular, this method allows the extraction agent intended for reuse to be recovered with a very high degree of purity, which not only benefits the quality of the treatment of the starting substrate, but also - due to the low "losses" of extraction agent - the economic efficiency of the process.

In a particularly preferred embodiment of this development, the multi-stage thermal separation stage can be realized by a combination of a thin-film evaporator and a condenser column, whereby the thin-film evaporation is used to first separate the extractant and other low-boiling substances (e.g. water) as vapor from the high-boiling hydrocarbon, before the vapor mixture of extractant and other low-boiling substances (e.g. water) is then separated in the condenser column into individual condensate streams (e.g. extractant condensate and water condensate).

The thermal separation stage, in which the extraction agent is isolated from the liquid fraction resulting from the mechanical solid separation to form a hydrocarbon-containing residue in which the high-boiling hydrocarbons are enriched, operates according to yet another preferred embodiment of the invention under an inert or inertized atmosphere (in particular under a nitrogen atmosphere). This prevents oxidation of the hydrocarbons contained in the hydrocarbon-containing residue. enriched high-boiling hydrocarbons are prevented, which improves their quality and thus their material usability. This in turn can significantly benefit economic efficiency.

However, if - due to the composition of the starting substrate - the liquid fraction resulting from the mechanical solid separation contains only two substances, namely the extraction agent and the high-boiling hydrocarbon extracted with it, a very good result can be achieved with a single-stage thermal separation stage (e.g. in the form of a thin-film evaporator), although here too the extraction agent must be liquefied in a condenser before it can be used again.

In an alternative embodiment of the present invention, which is modified from the development explained above, a hydrocarbon-containing residue formed in the multi-stage thermal separation stage by removing the extraction agent can - with a corresponding composition - be thermally separated into an aqueous fraction containing predominantly water on the one hand and an oily fraction containing predominantly hydrocarbons on the other. This separation, which is downstream of the separation of the extraction agent in terms of process technology, can in turn be carried out by means of thin-film evaporation, if the composition of the liquid fraction resulting from the mechanical solid separation is suitable for this purpose, possibly even in the same unit as the separation of the extraction agent.

In a preferred embodiment of the invention, the extractant isolated and re-condensed in the thermal separation stage is temporarily stored before being used again, wherein, if required, additional treatment of the returned extractant (e.g. by settling the suspended matter contained therein) can also be carried out in the container in which the temporary storage takes place.

Yet another preferred development of the invention is characterized in that the vapor fraction resulting from the vacuum evaporation is subjected to a multi-stage condensation to separate an aqueous condensate (and/or optionally an oily condensate) from the extractant contained in the vapor fraction. This design takes into account that the extraction agent circulated in the circuit does not reach the vacuum evaporation at all because it is already separated from the solid fraction fed to the vacuum evaporation upstream of this - namely in the mechanical solid separation upstream of the vacuum evaporation - but that a certain, more or less minor proportion of the extraction agent does reach the vacuum evaporation as part of the solid fraction. In implementing this development of the invention, this proportion of extraction agent is also fed to (internal) reuse - through circulating operation - so that the loss of extraction agent is minimized.

In yet another, particularly preferred embodiment of the method according to the invention, the starting substrate is the residue from an upstream pretreatment stage in which a raw substrate is subjected to a pretreatment carried out as vacuum evaporation in such a way that at least one low-boiling hydrocarbon and/or any water contained therein is separated from the raw substrate. This development proves to be particularly advantageous in the processing of a starting material (raw substrate) which contains water and/or various hydrocarbons that differ not only insignificantly in terms of boiling temperature. This is because the water or low-boiling hydrocarbons are separated early in the pretreatment stage, they do not pass through the downstream area of the processing plant explained above and therefore do not burden it; this downstream area can therefore be specifically designed and dimensioned for the separation of the at least one high-boiling hydrocarbon from the starting substrate. By removing low-boiling hydrocarbons and/or water from the raw substrate upstream of the extraction agent circuit, contamination of the extraction agent with water and low-boiling hydrocarbons is prevented. This is a very important aspect for the economic efficiency of the process, because the extraction agent is thus available to the greatest possible extent for the removal of high-boiling hydrocarbons from the starting substrate. The early separation of water or low-boiling hydrocarbons from the raw substrate in the pretreatment stage also simplifies the recovery of low-boiling hydrocarbons with a comparatively high degree of purity, which promotes material recycling.

To avoid misconceptions, it should be noted that a treatment stage which “only” precedes the above-described method according to the invention, but which is carried out at least partially in the identical facilities (with a time delay) can also be considered as an “upstream” pretreatment stage in the above sense. also) for the process according to the invention (in its basic form). In particular, in this sense the pretreatment carried out as vacuum evaporation can optionally be carried out in the same vacuum evaporator in which - in the process according to the invention in its basic form - the solid fraction resulting from the mechanical solid separation is also subjected to vacuum evaporation in batches (with a time delay) - dividing it into a solid residue and a vapor fraction. This is particularly useful when the quantities to be processed are comparatively small and the vacuum evaporator is only sporadically required to carry out the process according to the invention in its basic form.

Processing systems which are specially prepared for carrying out the above-described pretreatment of a raw substrate by means of vacuum evaporation by implementing additional components which form a spatially/functionally completely independent pretreatment stage in such a way that the pretreatment takes place in a separate area of the system, particularly preferably have a bypass to the said pretreatment stage, so that the substrate to be processed (as the starting substrate) can be fed directly to the mixing stage, possibly after prior comminution, bypassing the pretreatment stage. In other words: a material switch is provided here, via which the raw substrate is optionally fed either to the pretreatment stage or - as the starting substrate for the treatment according to the invention - directly to the mixing stage. This results in a processing system which can be easily and flexibly adapted to the respective substrate to be processed in terms of process control. This is a significant advantage, especially for mobile processing plants, which are used one after the other at different locations to process a wide variety of substrates.

The method according to the invention, particularly in its preferred embodiments explained above, is suitable for the processing of a wide variety of starting substrates for which satisfactory, practical recycling processes have not yet existed. These include in particular starting substrates which contain at least one metallic solid. An economically particularly relevant example of this are starting substrates arising in the metalworking industry which contain a mixture of metal particles and cutting oil. Another very important preferred application of the invention relates to the processing of starting substrates which contain at least one mineral solid. An economically extremely relevant example of this are starting substrates arising in the decontamination of contaminated soils which contain a mixture of sand and crude oil. Yet another, economically also very important application of the present invention relates to the processing of starting substrates which contain fibrous solids, in particular metal, glass or mineral fibers. Economically particularly relevant examples of this are starting substrates in the building materials industry that contain bitumen as a high-boiling hydrocarbon.

The above explanations of the method according to the invention readily provide a person skilled in the art with structural features of a device suitable and prepared for carrying out the method. In particular, a corresponding processing plant therefore has at least the following components - which are coupled and interconnected as intended to carry out the process according to the invention: material inlet for the starting material, mixing stage for adding the extractant to the starting material, homogenization stage, separation unit for mechanical solids separation to divide the starting substrate-extractant mixture into a solid fraction and a liquid fraction, vacuum evaporator for batch-wise division of the solids fraction into a solid residue and a vapor fraction, thermal separation stage for isolating the extractant from the liquid fraction to form a hydrocarbon-containing residue, recirculation device for returning the extractant recovered in the thermal separation stage by isolation together with extractant which is recovered from the vapor fraction of the vacuum evaporation for renewed addition to the starting substrate, separate outputs for the hydrocarbon-containing residue and the solid residue.

Advantageous structural developments of this device will become apparent to a person skilled in the art directly from the above explanations of preferred developments of the method according to the invention.

In the following, the present invention is explained in more detail using a preferred embodiment illustrated in the drawing. The drawing shows the relevant components and units of a processing plant suitable for carrying out the process according to the invention and the material flows characteristic of the process according to the invention; for the sake of better clarity, the material flows (paths) and the respective flowing Substances are designated with corresponding reference symbols.

The system illustrated in the drawing for the inventive processing of a pourable, flowable or pasty starting substrate, which contains at least one solid and at least one high-boiling hydrocarbon, has a material inlet 1, at which raw substrate is introduced. The material inlet 1 is followed by a material switch 2, by means of which it is possible to switch between processing the raw substrate with pretreatment or processing the raw substrate without pretreatment. In the basic concept - explained below - the raw substrate - without pretreatment - passes as starting substrate (path A) from the material inlet 1 via the switch 2 directly into a mixing stage 3, where it is mixed with a liquid extraction agent (path B), in which the at least one high-boiling hydrocarbon contained in the starting substrate is soluble.

The starting substrate-extractant mixture is then subjected to active mixing in a homogenization stage 4. In the illustrated preferred embodiment, however, the homogenization stage 4 and the mixing stage 3 form a structural unit in which both process stages take place, i.e. a uniform mixing reactor 5 that combines the mixing stage and the homogenization stage.

The homogenized starting substrate-extractant mixture (path C) withdrawn from the homogenization stage 4 is fed to a buffer tank 6 for intermediate storage, from which it is then fed (path D) to a separation unit 8 used for mechanical solids separation, illustrated here as a decanter 7 by way of example. There, the starting substrate-extractant mixture is subjected to mechanical solids separation, dividing it into a solids fraction containing predominantly solids (path E) and a liquid fraction containing predominantly liquid (path F). The optional multi-stage design of the mechanical solids separation was explained in detail above, as was the use of a different separation unit 8 (e.g. a filter press).

The solid fraction resulting from the mechanical solid separation (path E) is fed to a vacuum evaporator 9 (e.g. VacuDry ^® from the applicant), in which it is subjected to vacuum evaporation in batches, dividing into a solid residue (cleaned of organic contaminants) (path G) and a vapor fraction (path H) leaving the vacuum evaporator 9 via a filter 10. The solids contained in the starting substrate are concentrated in the solid residue.

The liquid fraction resulting from the mechanical solid separation (path F) is fed to a thermal separation stage 11, which is shown here as an example in two stages, namely as a combination of thin-film evaporator 12 and downstream condenser column 13. Here, the extraction agent and a possible water content (as steam) are withdrawn from the liquid fraction (path I), forming a hydrocarbon-containing residue (path K) that - like the solid residue (path G) - is discharged from the processing plant. The high-boiling hydrocarbons contained in the starting substrate are concentrated in this residue.

The extractant-water-vapor mixture (path I) discharged from the first stage of the thermal separation stage 11, i.e. the thin-film evaporator 12, is finally fed, together with the vapor fraction (path H) from the vacuum evaporator 9, to the condenser column 13 forming the second stage of the thermal separation stage 11, in which the extractant is isolated and separated from the water, namely by multi-stage liquefaction of the extractant-water-vapor mixture for separating condensation into an extractant condensate (path L) on the one hand and a water condensate (path M) on the other. The extractant condensate is temporarily stored in a buffer tank 14 before it is added again to the starting substrate in the mixing stage 4 (path B). The water condensate (path M) is discharged from the processing plant.

If the raw substrate to be processed contains not only at least one high-boiling hydrocarbon, but also at least one low-boiling hydrocarbon to a significant extent, then - with the appropriate switching position of the material switch 2 - a pretreatment of the raw substrate takes place in a pretreatment stage 15 serving to separate the low-boiling hydrocarbons. For this purpose, the raw substrate passes - via a dosing and feeding unit 16 - into a vacuum evaporator 17. The vapor fraction (path N) leaving this - via a filter 18 - containing vaporous low-boiling hydrocarbon is liquefied in a condenser 19 in order to be able to be discharged from the processing plant in liquid form. In the illustrated embodiment, this condenser 19 is designed as a condenser column 20 against the background that in the processing plant, if required, moist, i.e. Water-containing raw substrate can be treated. In this case, a hydrocarbon-water vapor mixture, which also contains water vapor, leaves the vacuum evaporator 17 via the filter 18 and is separated in the condenser column 20 by multi-stage liquefaction into a hydrocarbon condensate (path O) on the one hand and a water condensate (path P) on the other. The water condensate from the pretreatment stage 15 and the water condensate from the thermal separation stage 11 are discharged together (see water outlet 21). Likewise, unless the separation is maintained with a view to separate utilization, the low-boiling hydrocarbons (path O) and the high-boiling hydrocarbons (path K) can be discharged from the processing plant together (see KW outlet 22), as shown.

If the raw substrate is pretreated in the manner explained here in the described pretreatment stage 15, the starting substrate (path A`) for the processing described in detail above is formed from the residue of the vacuum evaporation in the vacuum evaporator 17.

• Betriebsdaten des Vakuumverdampfers 17 der Vorbehandlungsstufe 15: Innendruck im Verdampfer ca. 50mbar abs; Beheizungstemperatur bis ca. 400°C bzw. Materialtemperatur bis ca. 300°C; mittlere Verweilzeit ca. 240 Minuten. Die den Vakuumverdampfer 17 der Vorbehandlungsstufe 15 auf dem Pfad N verlassende Fraktion enthält als verdampfte Bestandteile Wasser sowie Kohlenwasserstoffe mit einer Kettenlänge bis ca. C 30.

The plant shown in the drawing is suitable, for example, for the treatment of soil contaminated with crude oil. For this application - when using toluene as the extraction agent - the operating parameters used are in the ranges given below:

• Operating data of the vacuum evaporator 17 of the pretreatment stage 15: Internal pressure in the evaporator approx. 50 mbar abs; heating temperature up to approx. 400°C or material temperature up to approx. 300°C; average residence time approx. 240 minutes. The fraction leaving the vacuum evaporator 17 of the pretreatment stage 15 on path N contains water as evaporated components and hydrocarbons with a chain length of up to approx. C 30.

Mixing ratio of extractant to solid in mixing stage 3 approx. 2:1 or higher. Average residence time in buffer tank 6 approx. 60 minutes.

The solids separation taking place in the separation unit 8 (designed, for example, as a decanter) produces, on the one hand - via path F - a liquid mixture of extractant and high-boiling hydrocarbons with a chain length > C 30 and, on the other hand - via path E - a highly viscous mixture, usually consisting of more than 50 wt.% mineral solids and extractant.

Operating data of the vacuum evaporator 9: Internal pressure in the evaporator approx. 50 mbar abs; heating temperature up to approx. 150°C or material temperature up to approx. 50°C; average residence time approx. 60 minutes. The fraction leaving the vacuum evaporator 9 on path H consists of the extraction agent toluene.

Thus, after complete treatment, the main fractions leaving the plant are a solids- and solvent-free crude oil fraction (path 22), which is prepared for material recycling in a refinery, a mineral fraction purified from crude oil with a feasible hydrocarbon target value of less than 0.1 wt. % (path G) and a water fraction (path 21).

Claims (25)

Method for preparing a pourable, flowable or pasty starting substrate containing at least one solid and at least one high-boiling hydrocarbon, with the following steps: - the pourable, flowable or pasty starting substrate (A, A`) containing at least one solid and at least one high-boiling hydrocarbon is mixed in a mixing stage (3) with a liquid extractant (B) in which the at least one high-boiling hydrocarbon contained in the starting substrate (A, A`) is soluble; - the starting substrate-extractant mixture is subjected to active mixing in a homogenization stage (5); - the homogenized starting substrate-extractant mixture (C) withdrawn from the homogenization stage (5) is subjected to mechanical solids separation (8) with division into a solids fraction (E) containing predominantly solids and a liquid fraction (F) containing predominantly liquid; - the solid fraction (E) resulting from the mechanical solid separation is subjected to a vacuum evaporation (9) in batches, dividing it into a solid residue (G) and a vapor fraction (H); - the extractant is isolated from the liquid fraction (F) resulting from the mechanical solid separation (8) in a thermal separation stage (11) to form a hydrocarbon-containing residue (K); - the extractant isolated in the thermal separation stage (11) is returned together with extractant recovered from the vapor fraction (H) resulting from the vacuum evaporation (9) for renewed addition to the starting substrate (A, A`); - the hydrocarbon-containing residue (K) resulting from the thermal separation stage (11) and The solid residue (G) resulting from the vacuum evaporation (9) is discharged separately from the processing plant. Procedure according to Claim 1 , characterized in that the starting substrate (A, A`) is subjected to comminution before the addition of the liquid extractant (B). Procedure according to Claim 1 or Claim 2 , characterized in that the addition of the liquid extractant (B) to the starting substrate (A, A`) and the active mixing of the starting substrate-extractant mixture take place in a uniform mixing reactor (5) combining the mixing stage (3) and the homogenization stage (4). Method according to one of the Claims 1 until 3 , characterized in that the homogenized starting substrate-extraction agent mixture (C) remains in a storage container (6) before the mechanical solids separation (8). Method according to one of the Claims 1 until 4 , characterized in that a multi-stage mechanical solid separation (8) takes place. Method according to one of the Claims 1 until 5 , characterized in that the mechanical solid separation (8) takes place at least partially in a filter press. Method according to one of the Claims 1 until 6 , characterized in that the mechanical solid separation (8) takes place at least partially in a decanter (7). Method according to one of the Claims 1 until 7 , characterized in that in the thermal separation stage (11) a multi-stage separation takes place with at least three outlets, namely an outlet for extraction agent, an outlet for an aqueous fraction containing predominantly water and an outlet for an oily fraction containing predominantly hydrocarbons. Procedure according to Claim 8 , characterized in that a vapor mixture formed in a first stage of the thermal separation stage (11) is condensed in a second stage of the thermal separation stage to form a water condensate (M) on the one hand and an extractant condensate (L) on the other hand. Procedure according to Claim 8 or Claim 9 , characterized in that in the thermal separation stage (11) the separation takes place by means of a thin-film evaporation (12) and a column condensation (13) downstream of this. Procedure according to Claim 8 , characterized in that a hydrocarbon-containing residue formed in the thermal separation stage (11) is thermally separated into an aqueous fraction containing predominantly water and an oily fraction containing predominantly hydrocarbons. Method according to one of the Claims 1 until 11 , characterized in that the extraction agent (L) isolated in the thermal separation stage (11) is temporarily stored after its re-liquefaction and before its reuse. Method according to one of the Claims 1 until 12 , characterized in that the vapor fraction (H) resulting from the vacuum evaporation (9) is subjected to a multi-stage condensation to separate an aqueous condensate and/or an oily condensate from the extractant contained in the vapor fraction. Method according to one of the Claims 1 until 13 , characterized in that the starting substrate (A`) is the residue from the pretreatment stage (15) in which at least one low-boiling hydrocarbon is separated from a raw substrate by means of vacuum evaporation (17). Procedure according to Claim 14 , characterized in that the raw substrate is fed to the pretreatment stage (15) via a switch (2), which optionally also allows the alternative feeding of the raw substrate as starting substrate (A) directly into the mixing stage (3). Method according to one of the Claims 1 until 15 , characterized in that the starting substrate (A, A`) contains at least one metallic solid. Procedure according to Claim 16 , characterized in that the starting substrate (A, A`) contains a mixture of metal particles and cutting oil or other high-boiling hydrocarbons. Method according to one of the Claims 1 until 15 , characterized in that the starting substrate (A, A`) contains at least one mineral solid. Procedure according to Claim 18 , characterized in that the starting substrate (A, A`) contains a mixture of sand and crude oil. Method according to one of the Claims 1 until 15 , characterized in that the starting substrate (A, A`) contains fibrous solid, in particular glass or mineral fibers. Method according to one of the Claims 1 until 20 , characterized in that the high-boiling hydrocarbon contains bitumen. Procedure according to Claim 21 , characterized in that the starting substrate consists of hydrocarbon-containing road demolition material. Method according to one of the Claims 1 until 22 , characterized in that the extraction agent contains an organic solvent, preferably consists at least predominantly of an organic solvent. Method according to one of the Claims 1 until 22 , characterized in that the extractant contains an organic acid, preferably consists at least predominantly of an organic acid. Plant for the processing of a pourable, flowable or pasty starting substrate containing at least one solid and at least one high-boiling hydrocarbon, comprising the following for carrying out the processing process according to Claim 1 components coupled and interconnected with one another: material inlet (1) for the starting material, mixing stage (3) for adding the extractant to the starting material, homogenization stage (4), separation unit (8) for mechanical solids separation for dividing the starting substrate-extractant mixture into a solid fraction (E) and a liquid fraction (F), vacuum evaporator (9) for batchwise division of the solid fraction (E) into a solid residue (G) and a vapor fraction (H), thermal separation stage (11) for isolating the extractant from the liquid fraction (F) to form a hydrocarbon-containing residue (K), recirculation device for returning the extractant recovered in the thermal separation stage (11) by isolation together with extractant which is recovered from the vapor fraction (H) of the vacuum evaporation for renewed addition to the starting substrate, separate outputs for the hydrocarbon-containing residue (K) and the solid residue (G).