SE508392C2 - Procedures for separating pollutants from a material contaminated with the pollutant - Google Patents

Abstract

A method of separating a contaminating substance, e.g. PCB, mercury, from a material contaminated with said contaminating substance, e.g. soil. The method involves heating the contaminated material in a first separation process and treating said material with a recirculating gas which is caused to pass repeatedly through the material in a closed circuit, a main loop (23), during the process while increasing in temperature to the boiling point of the contaminating substance present in said material, so that said contaminating substance will be successively expelled from the material and enriched in vapour phase in the recirculating gas. The expelled and enriched contaminating substance is separated from the gas in a second separation process carried out in a sub-flow loop (27). Any thermal energy that is released during the second separation process is returned to the closed circuit (23) and therewith supplied to the first separation process.

Description

508 392 2 Landfilling is a method that has often been used in the past, even though it does not solve the pollution problem but pushes it forward in time, to future generations.

Environmental toxins in such landfills will eventually also gradually leak to the surrounding soil, water and air. In recent years, legislation has been tightened regarding landfilling, including in the USA and Germany. This, combined with the introduction of landfill fees, will make landfilling a less attractive alternative to such remediation methods that aim to definitively address pollution problems.

Research and development of remediation methods based on biotechnology takes place to a significant extent, including in Germany and the USA. Great hopes have been placed, and are placed, on these methods. However, success has so far been limited. The naturally occurring bacteria used have difficulty in breaking down the heavier aromatic components in, for example, creosote; some components are toxic to microorganisms, hence the use of creosote as a wood preservative. However, new research findings indicate that anaerobic bacteria, ie those that live in an oxygen-free environment, have the ability to break down such substances as well. Effective and bacteria-based decontamination will therefore certainly take place in the future, but then probably in large, closed containers with an oxygen-free environment and for a long time and under constant treatment (temperature control, loosening, addition of nutrients, etc.). The costs will therefore be significant.

A fourth category of decontamination methods is extraction of the chemical substances with solvents (extractants), or washing with detergents of various kinds.

In the first case, the contaminated material is mixed with solvent, whereby contaminants are transferred to and enriched in the solvent. The method has been applied in various ways for a number of years, including in Denmark and Germany. The cost can vary, depending on, among other things, the type of material, water content and type and content of contaminants.

The applicability of the methods, especially the washing methods, is also strongly limited if the contaminated material is granular, ie contains clay.

A fifth method group consists of t_egn_isgiv¿dx'i_vrii_rig, with or without subsequent combustion of stripped pollutants. The present invention falls into this category.

German Patent Specification 4303722, for example, describes a method for stripping the contaminant sleeve from, for example, contaminated soil in a furnace with heated steam or hot gas containing oxidizing agent, the soil being freed from contaminating organic substances by direct oxidation in the material. Some of the substances are stated not to be oxidized in the material but to be evaporated and oxidized in a catalyst by catalytic oxidation or in a UV filter. 80 - 90% of the steam or hot gas is returned to the oven. 10 - 20% of the steam / hot gas is taken out for condensation, after which the rest of the non-oxidizing substances is separated from the condensation water by conventional methods.

When the steam / hot gas is introduced, an oxidizing agent containing oxygen is added. The purpose is that this oxidizing agent should be passed with the steam / hot gas through the material to thereby oxidize organic components therein, including organic pollutants. Enrichment of stripped pollutants is deliberately counteracted by continuous addition of oxidizing agents. There is an excess of oxygen in the steam or hot gas after the passage through the material, partly as residue and partly in the form of new supply, and therefore approximately 80-90% of the steam / hot gas + oxidant is recycled to the material.

The main debris from the furnace passes through a catalyst or a UV filter, whereby stripped contaminants are oxidized. A part fl desolation, 10-20%, is taken continuously for condensation followed by purification of the condensate water. Thus, some contaminants are oxidized in the material by the oxidant supplied with the steam or hot gas, while other substances are driven off and either oxidized by the catalyst or UV filter, or separated from the condensate by conventional methods after condensation of the steam / hot gas.

This known method entails a number of disadvantages. One such is that contaminated material often contains significant proportions of organic components, humic substances, wood fibers, etc., which consume the added oxidizing agent. Large quantities of oxidizing agents may thus be required, which entails additional costs.

Another disadvantage is that when 80-90% of the decomposition products recycle to the material, and if chlorinated substances occur and oxidize, the formed carbon dioxide, water (steam) and chlorine compounds will also recycle, which means continuous corrosion of the plant as chlorine is extremely corrosive .

A third disadvantage is the risk of ignition of the material or gas explosion. The described method means that the steam / hot gas contains an excess of oxygen. There is a risk that the organic constituents, not just pollutants, in the material may ignite due to the combination of oxidizable organic substances, oxygen and high process temperature (up to 700 ° C according to the text). There is also a risk that a hot and explosive mixture of gaseous pollutants and oxygen may be formed if such a mixture exceeds critical so-called LEL (Lower Explosive Limit) levels for various substances. The method is therefore risky, partly because the organic constituents of the material can catch fire in the furnace, partly because of the risk of explosion due to explosive gas mixtures in the plant.

It is also previously known, for example from U.S. Patent 5,172,709, that a chemical substance can be separated from a material containing this substance, by treating the material in a first step with water vapor so that the chemical substance is evaporated from the material with the water vapor. With this known method, however, the water vapor is then condensed directly with the chemical substance before the separation of the chemical substance from the water takes place in a second step. However, this method has been found to involve certain disadvantages of a technical and economic nature. The object of the present invention is, inter alia, to eliminate the above-mentioned disadvantages and enable a cost-effective separation method for industrial application, including soil remediation, and which is highly adapted to and utilizes the advantages of both so-called co-distillation with water and water vapor distillation and at the same time is to a large extent adapted to and utilizes the special chemical and physical properties of the chemical substances present in the material.

DEFINITIONS In the following, chemical substances in materials containing these substances are referred to as "pollutants" or "pollutants" when such a name is by definition justified, ie when such substances, according to the application of soil remediation chosen here for the purpose of the invention, are classified as harmful to the environment. .

By co-distillation with water is meant that water evaporates, which means that various pollutants due to the co-distillation principle can evaporate together with the water at the boiling point of the water even if the vapor pressure of the pollutants is extremely low at this temperature and their boiling point far higher than the water. By water vapor distillation is meant that the material is treated with superheated water vapor, whereby pollutants are evaporated from the steam. By "contaminated material" is meant soil, sediment, filling masses, etc. materials that contain the contaminating sleeve. The same applies to other applications of the invention, such as in certain industrial processes where separation of the chemical substances mentioned in the preamble from a material, solid or liquid, is desirable.

DISCLOSURE OF THE INVENTION The method according to the invention means that in a first separation process the contaminated material is heated and treated at a temperature up to the boiling point of the contaminant present with recirculating gas, which is passed through the material a rising number of times in a closed circuit during the process. , so that the pollutant present in the material is successively evaporated from the material and enriched in the vapor phase in the recirculating gas.

Stripped and enriched pollutants are separated from the gas in a second separation process in a part fl fate loop, whereby any released energy is returned to the closed circuit and thus the first separation process is supplied.

The separation of stripped pollutant from the gas takes place in either of three following ways, or different combinations thereof; Enriched contaminating sleeve is separated from the gas by combustion in a burner and / or in a catalyst, the heat energy formed being returned to the first separation process by means of heat exchangers. 2. Enriched pollutants are separated from the gas by cooling the gas and the substance, after which formed condensed water and non-condensable gases are purified from the pollutants in a conventional way, for example by uptake into chemical (filters (activated carbon). Enriched pollutant is separated from the gas by means of a pollutant-selective chemical substance, either a substance (a so-called sorbent) selected and arranged for the complete or partial uptake and binding of pollutants directly from the gas, or a sleeve selected and arranged for other chemical reaction, eg chemical precipitation, of polluting substance directly from the gas.

These and other features of the method according to the invention appear from the following claims. sos 592 6 DESCRIPTION OF THE FIGURES The invention will be described in more detail in connection with the accompanying drawings, in which Fig. 1 schematically shows diagrams of stripping processes for a number of pollutants A - E as a function of process temperature (° C) and process time (t); Fig. 2 shows a principle sketch of the process with a main loop 23 containing a process container 20 with particle filter 201 and an inlet 21 for contaminated material and an outlet 22 for treated material, a water injector 230, a fl 24 and a heating unit constituting a heat exchanger 26.

From the main loop 23 leads a part fl fate loop 27 which consists partly a sub-loop 271 with a dry-burning unit 25, constituting a burner and / or a catalyst, connected to the heating unit 26 and partly a sub-loop 272 with a unit 28 containing a pollution-selective nuclear substance.

Both of these sub-loops connect to a part-fate loop 273 with a unit 29 for gas cooling and condensation, which in turn is connected to a unit 291 containing a chemical filter for purifying formed condensed water and a unit 292 containing a chemical filter for purifying non-condensed water. condensable gas. The part fl loop loop 27 emanating from the main fl is also directly connected to this gas cooling and condensing unit. Purified condensed water is obtained at an outlet 2911 and returned to the treated material, and purified non-condensable gas at an outlet 2921 for discharge to the surrounding atmosphere.

Fig. 3 shows the main loop 23 according to Fig. 2 and the part fl fate loop 271 which comprises the combustion unit 25, connected to the unit 29 for gas cooling and condensation and further to the units for purifying formed condensed water 291 and for purifying non-condensable gas 292. Purified condensed water is obtained at a outlet 2911 and returned to the treated material, and purified non-condensable gas at an outlet 2921 for release to ambient atmosphere.

Fig. 4 shows the main loop 23 according to Fig. 2 and part fl fate loop 273 which connects directly to the unit 29 for gas cooling and condensation and further to the unit 291 for purification of condensed water formed and the unit 292 for purification of non-condensable gas. Purified condensed water is obtained at an outlet 2911 and returned to the treated material, and purified non-condensable gas at an outlet 2921 for discharge to the surrounding atmosphere.

Fig. 5 shows the main loop 23 according to Fig. 2 and part fl fate loop 272 comprising the unit 28 containing a pollutant-selective chemical substance, connected to the unit 29 for gas cooling and condensation and further to the units 291 and 292 for purifying formed condensed water and non-condensable gas, respectively. Purified condensed water is obtained at an outlet 2911 and returned to the treated material, and purified non-condensable gas at an outlet 2921 for discharge to the surrounding atmosphere.

Fig. 6 finally shows the main loop 23 according to Fig. 2 and part fl waste loop 271 comprising the combustion unit 25, and part fl waste loop 272 comprising the unit 28 containing a pollutant-selective chemical substance; both of these units are connected partly to each other and partly to the unit 29 for gas cooling and condensation and further to the units 291 and 292 for purifying formed condensed water and non-condensable gas, respectively. Purified condensed water is obtained at an outlet 2911 and returned to the treated material, and purified non-condensable gas at an outlet 2921 for discharge to the surrounding atmosphere.

DETAILED DESCRIPTION OF THE INVENTION First Separation Process Contaminated material is treated in a first separation process with gas, air or inert gas which is successively replaced with water vapor, whereby any contaminants are evaporated in vapor phase from the contaminated material. According to Dalton's law, each substance is enriched individually in the gas, independently of other simultaneously driven substances. By recirculating the gas through the contaminated material a large number of times in a closed circuit during the process, each substance is successively enriched in the gas.

As the process temperature, ie the temperature of the contaminated material, is gradually raised, the constituent pollutants will be driven off (of course, provided that they have a vapor pressure required for the purpose at the current process temperature; metals such as lead, copper etc. can therefore not be separated by this method ). sus 392 8 The gas can be obtained by this process to contain a surprisingly high content of the respective pollutant which has been evaporated from the material. The stripped substance follows the gas around the circuit and back through the material without recondensing (provided that the gas temperature does not fall below that required for the stripping of the substance) while more of the pollutant is continuously evaporated to the water vapor from the material.

The enrichment of substances takes place until an equilibrium state is reached, so-called "saturation". Since different substances have different vapor pressures and occur in highly varying initial levels in the material, the substances will thus be evaporated and enriched in the gas to different extents.

Some substances (eg low boiling) will quickly reach this iron weight position while others (high boiling) due to their low vapor pressure and / or low initial content do not even come close to their respective "saturation content" in the gas.

To facilitate the evaporation of contaminants in the first separation process, a chemical substance may be added to the contaminated material before or during the first separation process. The contaminated material is heated with flowing and heated recirculating air or inert gas in a closed circuit, called the main loop 23. With increasing material temperature, moisture in the material begins to form water vapor mixed with recirculating air or inert gas. Low-molecular-weight and low-boiling pollutants present in the material begin to evaporate and are evaporated and enriched in the air or inert gas. The temperature increase in the material takes place by heating the air or inert gas before recirculation to the material in the main loop.

As the material temperature approaches the boiling point of the water, a rapidly increasing amount of water vapor is added to the recirculating and heated air or inert gas. The gas volume thus increases in the main fate. This increasing gas volume, air or inert gas and water vapor, is withdrawn in a partial flow loop 27 from the main loop.

The composition of the recirculating gas in the main loop is thus gradually changed from air or inert gas to water vapor with increasing process and material temperature. At a material temperature corresponding to the boiling point of the water, the gas consists mainly of water vapor from part of the evaporated water content of the material. 9 sus 392 The gas extracted from the main loop in part fl the fate loop contains, in addition to air or inert gas followed by air or inert gas and water vapor and finally water vapor, also pollutants which are evaporated in vapor phase from the material and enriched in the gas by co-distillation with water or water vapor distillation. This occurs during all phases of the process and is conditioned by the properties of the substances; low-boiling substances are evaporated at a lower temperature than high-boiling substances. The gas extracted in part fl of the fate loop can therefore contain different types and contents of stripped substances, as a function of mainly the process temperature and degree of enrichment (saturation) in the gas.

Through so-called co-distillation with water (water codistillation), certain high-molecular-weight and high-boiling pollutants can be evaporated and evaporated and enriched in the gas already at low temperature, such as the boiling point of water.

At a process temperature corresponding to the boiling point of the water, the gas consists of water vapor and evaporated pollutants. When all the moisture in the material has evaporated by the recirculating heated water vapor in the main loop, the material temperature rises above the boiling point of the water and up to the temperature required for the remaining pollutants to evaporate and be driven off the material. The temperature is regulated to the required level by heating the water vapor with a heating unit during its recirculation in the main loop of the material.

When the material has dried, no new water vapor is formed for extraction in the part-fl loop, which means that stripped contaminants can be enriched to an even greater extent in the recirculating water vapor in the main loop than during the evaporation of the moisture in the material. However, a small part of the water vapor in the main loop is taken out in part fl the fate loop during the temperature increase to compensate for the volume increase that the temperature increase results in.

The material is treated with gas at a temperature up to the boiling point of the polluting medium and at atmospheric pressure or as close to atmospheric pressure as the technical design of the process allows.

To remove water vapor and enriched pollutants in a controlled manner during the high-temperature phase, ie when water vapor is no longer produced from evaporated moisture in the material, water is injected into the main loop. The water evaporates, which leads to an increase in volume in the main loop which is compensated by withdrawing the corresponding volume in the 508 392 10 part fl fate loop. Thus, by injecting a certain volume of water, a fixed volume of water vapor containing enriched contaminant can be withdrawn from the main loop to the partial flow loop.

Gas taken from the main loop in the partial flow loop is led to the second separation process for separating enriched pollutants from the gas, which is then either recycled to the main loop, or taken out of the system.

Other separation processes After evaporation, the substances are separated from the gas in a second separation process in a sampled part fl desolation in either of three ways, combustion, complete or partial uptake on a pollutant-selective substance, separation after cooling and condensation of the gas, or in different combinations of these three ways. The choice of separation method or methods depends on the number, type (s) and levels of enriched pollutants.

The separation can take place from the start of the respective substance enrichment in the gas and until the particles have reached their respective "saturation levels" in the recirculating gas. 1 Separation by combustion A separation method is to destroy pollutants in a removed part fl desolate by combustion directly in the gas. This presupposes that the substance in question is combustible, ie a hydrocarbon compound. The destruction takes place by passing the gas containing such a substance to a combustion unit, whereby the substance is combusted (oxidized) and decomposed into water vapor and carbon dioxide and - for chlorinated hydrocarbons - also gaseous chlorine. In cases where chlorinated hydrocarbons are combusted, chlorine (probably as chlorine gas) can then be separated from the gas by passing the gas after the combustion unit to a chemical substance, a chlorine-selective sorbent (see below), which absorbs and binds the chlorine as the gas passes through.

The combustion unit consists of a burner, a catalyst or a combination of burner and catalyst. During the combustion of pollutants, heat energy is developed. An advantage of this process is that at the same time as the substances are annihilated, heat energy is developed which can be directly utilized and used in the process by supplying the energy via heat exchangers to the first separation process. Another advantage is that there is no need for either sorbent or disposal of concentrate of contaminants (see below), which is obtained when regenerating the sorbent.

To achieve maximum destruction of pollutant in the gas, the gas can be recycled a number of times through the combustion unit.

The heat energy released during combustion is transferred to the gas in the main loop via heat exchanger.

The gas can then be returned to the process, or taken out of the system. Gas that is extracted is cooled to below the boiling point of the water, after which formed condensed water and non-condensable gases pass through chemical filters, adapted for the uptake of any residues of pollutants. The condensed water is then returned to the treated material and the gas is released to the surrounding atmosphere. 2 Separation after cooling and condensation A second separation method to separate pollutants in a part fl fate is that the gas is cooled down to below the boiling point of the water, after which the substances are separated formed condensed water and non-condensable gases in a conventional way using chemical filters (eg activated carbon). has the property of absorbing and binding the contaminating sleeve directly from the non-condensable gas and the condensed water, respectively.

Residues of pollutants can also be separated from the condensed water and non-condensable gas by filling, etc.

The enrichment of pollutants in the gas during the first separation process in the main loop means that when the gas is extracted and cooled / condensed, there is a correspondingly high enrichment of substances in the condensate water and / or non-condensable gas.

This is a considerable technical and economic advantage compared to such methods which perform condensation of water vapor which has once passed through a contaminated material.

The condensed water is returned to the treated material and the gas is released to the surrounding atmosphere. 508 392 12 3 Separation by means of substance-selective chemical substances A third separation method, where the pollutants are not destroyed directly in the gas or cooled with the gas as above, is to separate enriched pollutants in a part fl fate by letting the gas pass a substance-selective chemical substance that is selected and arranged to take up or otherwise chemically separate the polluting substance or group of pollutants from the gas.

To achieve maximum separation of the pollutant from the gas, it can be recycled a number of times to the pollutant-selective chemical substance. By allowing the gas to pass through two or more such chemical arrays in series, various pollutants or groups of substances enriched in the gas can be selectively separated from the gas.

A type group of chemical substances (so-called sorbents) is characterized by the fact that they absorb and bind an antique pollutant from the gas in a non-destructive way. Another type group of chemical substances, so-called dehalogenating sorbents, is characterized by the fact that they take up enriched chlorinated hydrocarbon compounds, eg PCBs (polychlorinated biphenyl), from the gas while the chlorine bonds are broken and the chlorine atoms are released: The biphenyl part of the PCB molecule is taken up and bound to the chemical substance while the chlorine atoms are released and accompany the gas. This liberated chlorine (probably as chlorine gas or other gaseous chlorine compound) can then be taken up on another and chlorine-selective chemical substance as the gas passes through.

The gas can then be returned to the process, or taken out of the system. Gas that is extracted is cooled to below the boiling point of the water, after which condensed water formed and non-condensable gases pass through chemical filters, adapted to absorb any residues of pollutants. The condensed water is then returned to the treated material and the gas is released to the surrounding atmosphere. Combination of separation methods 1 - 3 above These separation methods can be applied individually or in combination with each other, the latter if the material is contaminated with two or more types of substances or groups of substances that can not be separated from the gas with one and the same separation method, which often is the case.

B sos 592 EXAMPLES An example of the separation of a plurality of pollutants from a polluted material shall now be briefly described before connection to Fig. 1 and Fig. 2- 6. It is assumed that a material (eg soil) is polluted with fl your various pollutants or groups, named A - E (Fig. 1), each of which exhibits different behaviors during treatment, ie they are stripped from the material at different temperatures, have different properties and / or form decomposition products which mean that they must be separated from the gas in different ways. Substance A is evaporated during the heating phase, substance B and (partially) substance C during the drying phase, and substances D and E are evaporated during the high temperature phase. This example has been simplified for the sake of clarity; in reality, many of these different substances are evaporated under significantly wider and thus strongly overlapping temperature ranges. This fact means that the different separation methods are used simultaneously during the process, for example by passing the gas with enriched pollutants in the part-loop loop to, for example, a unit for uptake on a type of pollutant-selective sorbent and then to a combustion unit or vice versa. for example another type of chlorine or pollution selective sorbent.

In practice, process fates can be unchanged throughout the process; gas fl fate passes continuously through different separation units in series; these units fulfill their respective function as the gas during the process carries with it the pollutants or decomposition products which the units are designed to separate from the gas.

The process consists of three phases; the heating phase with a temperature up to 100 ° C, a drying phase with a temperature of 100 ° C and a high temperature phase of up to, in this example, 500 ° C. Subject A Mercury, Hg, in metallic (elemental) form.

Metallic Hg is slightly volatile and is rapidly evaporated in the vapor phase from the contaminated material already below 100 ° C, ie the heating phase, see Fig. 1. Hg cannot be destroyed and must therefore be separated directly from the gas by means of a Hg-selective chemical substance (sorbent). _Å__mLB Lightweight - medium petroleum hydrocarbons.

This substance is actually a group of substances consisting of aromatic and / or aliphatic sus 392 M hydrocarbons which gradually emit at a temperature of about 100 ° C, ie during the drying phase; the lighter ones are expelled first and the medium ones afterwards, to be destroyed by incineration. Subject Medium-heavy - heavy hydrocarbons This is an inert group consisting of aliphatic hydrocarbons which gradually emit at a temperature of about 150 - 200 ° C, ie during the high temperature phase. The substances are destroyed by incineration. Subject D PCB PCB is a collective term for an aromatic hydrocarbon group consisting of a biphenyl group with different chlorine content, constituting a number of so-called PCB congeners; this chlorine is released if the PCB molecule breaks down. The heaviest and structurally most "flat" PCB cones are stripped from the material at 250 - 300 ° C.

PCBs can be destroyed by combustion, with chlorine being one of the decomposition products. PCBs can also be taken up by PCB-selective chemical substances, either a PCB-selective sorbent which takes up and binds the PCB molecule or a so-called dehalogenating sorbent which takes up the biphenyl group of the PCB molecule but releases the chlorine atoms of the PCB molecule. The chlorine formed during combustion and uptake on dehalogenating sorbent can then in turn be taken up by a separate chlorine-selective chemical substance (sorbent). Subject E Mercury in the form of mercury ul d, HgS HgS is a solid compound (and a naturally occurring Hg mineral), formed in Hg-contaminated soil of metallic Hg and sulfur. To separate Hg, the material must be heated to approximately 500 ° C; under certain conditions a lower temperature is sufficient. The compound is thereby decomposed and Hg is evaporated as (probably) metallic Hg, which is separated directly from the gas by an Hg-selective chemical substance (cf. substance A above).

The contaminated material consists of "normal" moraine soil containing 10-20% water.

The various substances A - E will be evaporated as the material is heated from the initial temperature up to the highest process temperature 500 ° C. (5 508 392 As the fins are stripped from the material, they are separated from the gas in part fl the nozzle loop by the selected separation methods, ie by combustion or by a selective chemical substance, or combinations of these methods. The separations can take place by passing the sorbent and combustion unit one after the other (or vice versa), or by passing the gas to the mercury-selective sorbent during the process temperature range when mercury is evaporated from the material, or by passing it to the combustion unit during the process temperature range when the petroleum products are evaporated from the material.

As illustrated in Fig. 2, the process involves a main desolation in the main loop 23 continuously for the evaporation and enrichment of the pollutants, and an outlet (continuously or periodically depending on the actual process phase - see above) in the part-desolation loop 27 for separating enriched substances from the gas.

The process is set according to Fig. 5, with a main loop 23 for recirculating gas and a part del fate loop 272 with a unit 28 containing a mercury-selective substance.

Contaminated material is fed at 21 to a closed process vessel 20 having a particle filter 201. Existing air in the system begins to circulate in the closed main loop 23 by means of a fan 24 and is continuously heated by a heating unit, heat exchanger 26, before the passage to and through the process vessel 20. .

The material then begins to gradually deteriorate and the moisture in the material begins to evaporate.

At 70-80 ° C, more than half of the air in the main loop has been replaced by water vapor. A significant portion of sleeve A is evaporated to the gas in the main loop 23.

In the presence of slightly polluting impurities in the material, which can lead to a gas explosion risk during heating in the presence of oxygen, the air (actually the oxygen content of the air) is completely or partially replaced by inert gas before heating begins.

From the main loop 23, part fl fate to part fl fate loop 272 of the process gas (air or inert gas and later water vapor) takes place. This part fl fate is automatically generated by a suitable valve means, due to pressure and volume increase in the main loop. Stripped and enriched pollutants A are then taken out with the gas and led in part fl the loop 272 to the unit 28 containing the mercury selective substance where the mercury in the gas is taken up and bound while the gas passes through to either be returned to the main loop 23 or taken out of the system 29 , 291, 292 for gas cooling and condensation and purification of condensed water and non-condensable gas respectively.

When the temperature has reached 100 ° C, substance A has been evaporated and taken out in part fl loop loop 272 for uptake on the mercury-selective sorbent 28, and all air or inert gas in the main loop 23 has been replaced by water vapor formed from the evaporation of moisture in the material. The sorbent containing the mercury is taken out for regeneration, whereby the mercury is obtained as a concentrate and the sorbent is reused in the process.

The sorbent can also be of a disposable nature, ie taken out of the process for final disposal together with the mercury, and replaced with a new and unused sorbent substance.

The process is now set according to the fate of Fig. 3, with the main recirculating gas loop 23 and a portion of the fate loop 271 having a unit 25 containing a combustion unit consisting of a burner and / or a catalyst. Subject B begins to be stripped. The water vapor formed from the moisture of the material is taken with stripped substance B continuously from the main loop 23 to the part loop 271 and the combustion unit 25. Substance B is destroyed and released heat energy is transferred via the heat exchanger 26 connected to the combustion unit to the gas in the main loop 23.

The gas and formed decomposition products, water vapor and carbon dioxide, are passed on to the unit 29 for gas cooling and condensation, after which the condensate (from the water vapor) and non-condensable gas (carbon dioxide) pass the respective units 291 and 292 for purification.

In the case where the material is initially dry, water vapor cannot be formed internally by material moisture during use. Water is then added instead from the outside to the main loop 23 via the water injector 230 for evaporation in order to thereby "artificially" form water vapor for replacement of air or inert gas.

When during the further process the material in the process vessel 20 has dried out, substance B has been evaporated and incinerated. Water vapor is no longer formed by the heating of the material. The material is now starting to heat up to above the boiling point of the water. The process remains tuned in accordance with Fig. 3, as substance C, like substance B, consists of combustible hydrocarbons. 17 5 Û 8 3 9 2 Due to an increase in volume and thus pressure during the temperature increase in the main loop, a certain but limited volume of water vapor, and substance C, will be taken out in part fl the fate loop.

However, most of the water vapor in the main loop 23 recirculates through the material as the temperature of the material rises and the contaminant antenna C is increasingly driven off and enriched in the steam. By injecting a certain volume of water into water injector 230 in the main loop before the heating unit, i.e. the heat exchanger 26, this injected water is evaporated to a certain volume of water vapor, which results in volume increase in the main loop 23 and an automatic withdrawal of the corresponding volume of water vapor to part fl loop loop 271.

In this way, part fl the fatal withdrawal from the main loop of water vapor enriched pollutant C can be checked and taken out in an enriched content in the water vapor suitable for combustion. Subject C has now been dismissed. The temperature in the process continues to rise. The process is set in accordance with Fig. 5 or Fig. 6, depending on the circumstances; both process settings allow the separation of substance D from the gas (water vapor). Substance D now begins to be stripped from the material and enriched in the gas in the main stream 23. By water injection in injector 230, part fl of the gas and substance D are taken from the main loop 23 to part fl the loop 271 for separating sleeve D from the gas.

According to Fig. 5, the part fl fate loop contains a contaminant-selective substance, ie here a PCB-selective sorbent. This can consist of, for example, fl polyethylene glycol (PEG) or polypropylene glycol (PPG) which both efficiently absorb and bind substance D, ie PCBs, from the water vapor. The sorbent can also consist of a so-called dehalogenating sorbent, for example alkali metal-containing polyethylene glycol (APEG) or polypropylene glycol (APPG).

These take up substance D at the same time as the bond between the biphenyl group and the chlorine is broken in the PCB molecule; the biphenyl group binds to the sorbent while the chlorine remains in the gas form, such as chlorine gas or other chlorine compound.

The gas and chlorine gas are passed on to a unit containing a chlorine selective sorbent which picks up and binds the chlorine, while the gas passes through and is returned to the main loop 23 or taken out of the system via the gas cooling and condensing unit 29 and the condensate water purification unit 291; since the gas consists of water vapor, no purification or emission of non-condensable gas takes place, 508 392 y ß The sorbent is regenerated to give the biphenyl group as a concentrate for disposal, and the sorbent is reused in the process. The sorbent can also be of a disposable nature, ie taken out of the process for disposal together with the biphenyl group, and replaced with a new and unused sorbent tern.

According to Fig. 6, part fl the fate loop contains partly a combustion unit 25 and partly a unit 28 with a pollution-selective core, consisting of a chlorine-selective sorbent. The part fl of the gas and enriched pollutant D is first led to the combustion unit 25, whereby substance D is decomposed into water vapor, carbon dioxide and chlorine gas or other gaseous chlorine compound. Formed heat energy is returned with the gas via the heat exchanger 26 to the main loop 23.

The gas and decomposition products are then passed to the chlorine-selective sorbent 28 which absorbs and binds the chlorine, while the gas passes through and is taken out of the system via the gas cooling and condensing unit 29 and the condensing water and non-condensable gas units.

The process temperature increases continuously. Topic D has now been dismissed. The process is again set in accordance with Fig. 5, with a unit containing a mercury-selective sorbent (same as in the uptake of substance A).

The process temperature increases to the temperature range where substance E present in the material, ie mercury fi d, HgS, is decomposed thermally, whereby released (probably) metallic mercury is evaporated and enriched in the gas in the main loop. By injecting water into the main loop 23, a teachable gas fl desolate containing mercury is taken out in part fl of the loop 272, which is cooled (but not below the boiling point of the water) and passes the mercury-selective sorbent where the mercury is taken up while the gas passes through. The gas is returned to the main loop 23 or taken out of the process via the gas cooling and condensing unit 29 and subsequent unit 291 containing chemical purification salts for condensed water.

When substance E has been stripped from the material, this is finalized, whereby the process is interrupted.

Water is fed into the system so that the gas in the main stream is first diluted and then emptied.

The material is cooled with gas and / or water, whereby the energy can be recovered and led to another process container where the corresponding process is taking place, and is discharged from the container at 22. New contaminated material is filled and the process is repeated.

Claims (14)

19 508 392 PATENT REQUIREMENTS 1. l. Procedures for the separation of pollutants, such as chemical substances such as PCBs, dioxins, aliphatic and aromatic substances in creosote, oil and other petroleum compounds, and other chemical substances with similar chemical and physical properties as the first-mentioned chemical substances, and distillable metals such as mercury and distillable compounds of such metals, from a material contaminated with the contaminating substance, characterized in that in a first separation process the contaminated material is heated and treated with recirculating gas which is passed to the boiling point of the contaminant present at rising temperature. through the material a large number of times in a closed circuit, main loop (23), during the process, so that the pollutant present in the material is successively evaporated from the material and enriched in vapor phase in the recirculating gas, and thus stripped and enriched pollutant in a second separation process in a partial flow loop (27) sep from the gas. Method according to Claim 1, characterized in that during the second separation process any released heat energy is returned to the closed circuit (23) and thus the first separation process is supplied. Method according to claim 1, characterized in that the heating of the contaminated material with gas takes place by heating the air in the main loop (23) by means of a heating unit and causing it to circulate in the loop by means of a fl (24), wherein in the contaminated the water present in the material is gradually evaporated; 508 392 20 that, when the gas pressure in the main loop has reached a certain predetermined value, air, water vapor and evaporated and enriched pollutant are diverted to the part fl dew loop (27); and that, when all the air has been diverted from the main loop (23) and the contaminated material is dry, water vapor and in the water vapor enriched contaminating medium is removed to the part-loop loop (27) by injecting water into the main loop, which is further evaporated by the heating unit. Process according to Claim 3, characterized in that oxygen in the air present in the main loop (23) is replaced by inert gas. Method according to one of Claims 1 to 3, characterized in that in the second separation process in the part-loop loop (27), the gas and enriched vapor-contaminating sleeve are passed to a separation unit containing a combustion unit (25) for disintegrating the contaminating scar. Process according to Claim 5, characterized in that in the second separation process in the part-d loop (27), the gas and enriched vaporous substance are passed to the separation unit, the combustion unit (25) being a burner and a catalyst. Method according to Claim 5, characterized in that in the second separation process in the part-d loop (27), the gas and enriched vaporous substance are passed to the separation unit, where the combustion unit (25) consists of a burner. 2, 508 392 Method according to Claim 5, characterized in that in the second separation process in the part-loop loop (27), the gas and enriched vaporous substance are passed to the separation unit, where the combustion unit (25) is a catalyst. 9. A method according to claim 5, characterized in that formed decomposition products and the gas before being taken out of the process are passed through a separation unit containing a chemical substance, selected and arranged to separate decomposition product from the gas. Process according to Claim 1, characterized in that in the second separation process in the part loop (27) the gas and vaporous pollutant are cooled, after which the pollutant is separated from formed condensed water and non-condensable gas. Process according to Claim 1, characterized in that in the second separation process in the part loop (27) the vaporous pollutant and the gas are passed through a separation unit containing a pollutant-selective chemical substance (28), selected and arranged to separate the gas pollutant after which the gas is taken out of the system. 508 592 22 Method according to claim 1, characterized in that in the second separation process in the part-fl loop (27) the vaporous pollutant and the gas are passed through a separation unit containing a pollutant-selective chemical substance (28), selected and arranged to separate the pollutant, after which the gas is returned to the main loop (23). Method according to claim 1, characterized in that in the second separation process in the partial flow loop (27) the vaporous pollutant and the gas are passed through a separation unit containing a pollutant-selective chemical substance (28), selected and arranged to decompose the gas pollutant and absorb part of the decomposed pollutant. 14. A method according to claim 13, characterized in that after the separation unit containing the pollutant-selective chemical substance (28), the gas and formed decomposition product is passed to another separation unit containing a chemical substance, selected and arranged to receive formed decomposition product from the gas.