EP2480349A1 - Method and reactor for treating bulk material containing carbon - Google Patents

Abstract

The invention relates to a method for treating bulk material which contains carbon and impurities. According to the invention, bulk material is directly heated inductively inside a reactor.

Description

 Process and reactor for the treatment of carbonaceous bulk material

The invention relates to a process for the treatment of carbonaceous bulk material containing impurities and to a reactor for carrying out the process.

Carbonaceous shaped articles, such as furnace linings, find application in high temperature furnace liners or cathodes. For example, cathodes made of amorphous carbon, graphite-added amorphous carbon or graphite in electrolysis cells (electrolysis cells are also called "pots") are used for aluminum electrolysis at the end of the life of the cathodes, these fluorine and cyanide, and aluminum and / or aluminum compounds Due to stricter legal requirements, such spent carbon linings, also known as spent potlining (SPL), must not be stored in landfills without treatment, used as fuel or reused as raw material.

A method for treating SPL is described, for example, in US Pat. No. 5,164,174. In this case, a conventional rotary kiln is used, which is heated directly with a gas flame. In an oxidizing atmosphere, at least a majority of the carbon is converted to carbon monoxide and dioxide. As a result, the carbon is consumed, and in addition there are large quantities of gases that make large dimensions of the rotary kiln and the subsequent gas purification stages necessary.

In US 5286274 a closed electric melting furnace is used. A disadvantage here are the dimensions of the facilities that are designed too large, at least for individual huts and require a wide-ranging logistics network. at In this process, a considerable part of the carbon is oxidized directly to CO ₂ and thus removed from further utilization.

The object of the present invention is to provide a method by means of which spent potlining and carbonaceous stones can be processed with the aid of a small-volume reactor.

The object is achieved with all features of the method according to claim 1. Further developments of the method according to the invention are specified in the dependent claims 2 to 21.

It is essential to the invention that carbon-containing bulk material containing impurities is heated directly inductively for its preparation in a reactor. Direct inductive heating is possible because the bulk material has such an electrical conductivity that frequencies of an induction heater couple into the bulk material and heat it directly, without the need for coupling into an additional medium. The inventive method has the advantage that do not incur by combustion reactions large amounts of combustion gases that make a correspondingly large volume reactor required. In addition, a reactor wall does not need to be heated, resulting in only a small heat loss across the reactor wall and thus a very high energy efficiency of the process.

In the context of the invention, treatment is understood to mean a treatment of carbonaceous stones, with which toxic impurities are removed from the stones and / or converted into non-toxic compounds, wherein this treatment is carried out to such an extent that these stones do not endanger the environment or people can be stored in landfills, used as raw material and / or used as fuel.

The carbon of the bulk material can be present, for example, as amorphous carbon, natural graphite, synthetic graphite or in any other arbitrary form. All that needs to be done is inductive coupling. Preferably, the bulk material contains at least one bulk material selected from the group consisting of broken cathodes from an aluminum melt recovery process, broken anodes, crushed carbon liners from a steelmelt, a steel blast furnace or other metal smelting furnace, a glass melting furnace, a ceramic melting furnace, and other carbonaceous bricks to be processed.

The impurities may contain at least one impurity selected from the group consisting of cyanides and soluble fluorides. For example, these impurities accumulate in the cell lining during molten aluminum electrolysis and are toxic contaminants that prevent storage or reuse of the bulk material. However, the impurities may also contain, for example, sulfur and / or alkalis, such as Na and Ka, and non-ferrous metals, such as Zn.

Advantageously, bulk material is used which has over 50 wt .-%, a particle size of about 30 mm, in particular to over 50 wt .-%, a particle size between 50 and 150 mm. In the case of such particle sizes, it has been found within the scope of the invention that inductive fields couple very well into the bulk material. Such high particle sizes have the advantage that not consuming and therefore energy and cost intensive grinding steps are required, but relatively coarse cracked bulk material can be used.

In this case, however, a fine fraction of less than 50 mm, in particular less than 30, in particular less than 10 mm remain in the bulk material. Even as fines present fine fraction can remain in the bulk material. The fines are indirectly heated by the coarse fraction. This makes a separation of fine and coarse part of the bulk material before carrying out the method according to the invention unnecessary.

The bulk material can be obtained by breaking up reprocessed moldings and / or bricks with an example conventional crusher. This may advantageously be a jaw crusher, cone crusher, gyratory crusher or similar crusher. These are suitable for achieving desired coarse grain sizes and are readily available as conventionally used crushers. According to one aspect of the invention, carbonaceous stones to be crushed into bulk material are broken out of an SPL, a cathode block, a furnace lining or a similar installation situation prior to breaking. Under a similar installation situation, in the context of the invention, a substantially regular arrangement of stones at a place of their use, in which they fulfill their task, such as high-temperature resistance and containing a melt understood. Thus, the bricks need not be removed one by one, but can be "mined", for example, by conventional machines which are conventionally used for demolishing the building, enabling the bulk material to be obtained with little effort and therefore at low cost and in a short time frame.

The impurities may contain aluminum. The aluminum may be present in metallic form, as an oxide, as a carbide and / or in another chemical compound. Particularly in aluminum-melt electrolysis, a carbon lining or a cathode is contaminated with aluminum as a metal or as a chemical compound.

The impurities may contain iron. In this case, the iron can be present in metallic form, as oxide, as carbide and / or in another chemical compound. In particular, in the steelmaking or molten steel process, a carbon lining becomes contaminated with iron as a metal or as a chemical compound.

Advantageously, induction fields are generated with frequencies between 1 and 50 kHz, in particular between 1 and 10 kHz, in particular between 2 and 5 kHz. At these low frequencies, the induction fields couple well into coarse grains. Maximum temperatures up to 2500 ° C can be generated in the reactor. This is possible by the direct coupling of the induction fields in the bulk material.

In the reactor, maximum temperatures between 1250 and 1800 ° C., in particular between 1300 and 1750 ° C., in particular between 1450 and 1700 ° C., are preferably set. These temperatures are high enough that cyanides decompose under the action of water vapor, which starts at around 700 ° C and cyanides are cracked and AIF3 is sublimated, which starts at around 1300 ° C. In contrast, these temperatures are low enough that no or at least hardly forms silicon carbide, because from a thermodynamic point of view, the formation of SiC begins only from 1700 ° C.

In the process, at least a portion of the contaminants may be dissolved in an existing and / or forming slag in the process. This slag can be formed from the already existing impurities with Al compounds and / or Fe compounds as main constituents.

Advantageously, at least one slag image and / or a flux are added to the reactor. Slag formers facilitate the formation of a slag, fluxes lower their viscosity, so that the slag can flow more easily and thereby absorb impurities. Impurities present on a surface of the bulk material can thus be washed off the bulk material by means of the slag. According to a possible embodiment of the invention, a calcium-containing compound such as CaO, CaCO 3 or dolomite, and / or a silicon-containing compound such as SiO 2 or a silicate, and / or an iron-containing compound such as an iron oxide or Iron ore, added. These form a slag together with the optionally present aluminum compounds of the bulk material. In this case, for example, Si compounds can act as flux. In the case of the use of bulk material, which does not come from the production of aluminum, a slag can form even in the absence of aluminum. The said added compounds can advantageously also as Slag to be added. Iron-containing compounds are suitable, for example, to bind sulfur present as an impurity as iron sulfide.

The slag can advantageously flow into a lower zone of the reactor, where it collects and is removed from there. This allows the process to be carried out continuously. The slag can be mixed with bulk material.

The slag may at least partially solidify in the lower zone. This occurs, for example, in that the lower zone is not inductively heated. Nevertheless, in addition to the solidified slag in the lower zone, there may also be a liquid fraction of slag.

From the lower zone, the slag is removed. This can be done by means of a slider and / or a crusher. After removal, bulk material and slag advantageously slip into the lower zone.

Preferably, water and / or water vapor is introduced at least in one zone of the reactor. This can be done by atomizing or misting. In the following, water and / or water vapor are also only referred to as water, which may of course be present in gaseous and / or vapor form at the corresponding temperatures.

The introduction of water can advantageously fulfill several functions. Thus, chemical compounds can be hydrolytically and / or pyrohydrolytically decomposed. For example, cyanides can be decomposed pyrohydrolytically.

Furthermore, bulk material and / or additives can be introduced into the reactor in a moist state. The water thus introduced can also fulfill the functions described above. In moist bulk material induction fields can be coupled as described for dry bulk material. Furthermore, the slag and the carbonaceous bulk material can be separated from one another by quenching with water. This can advantageously be done in the lower zone and / or a lower region of a central zone of the reactor, where the slag melt, especially in a low-viscosity state, strongly wets the bulk material. By contact with water slag and bulk material are cooled quickly, which leads to mechanical stresses that can cause a slipping of the slag from the bulk material. This has the advantage that in a mixture taken from the reactor slag and bulk material, although juxtaposed, but already separated from each other.

Slag and processed bulk material can be separated from one another by conventional methods, for example by flotation methods.

The slag and the then cleaned bulk material can be reused after removal. The slag can be used as an additive for example in construction materials, such as cement. For this purpose, it is advantageously ground. The carbonaceous bulk material can be used for example as a fuel. Alternatively, the carbonaceous bulk material can be used as a material in, for example, wear liners, such as gutters. This is possible because the bulk material after the process still has a very high strength and has retained its graininess. Of course, the carbon of the bulk material can be used for all other applications in which conventional carbon is used that has not already been industrially used and subsequently processed. In the method according to the invention, at least part of the impurities is advantageously converted into a gas phase. This facilitates removal of the contaminants.

For example, at least one of the following steps is performed:

 Pyrohydrolytic decomposition of compounds such as cyanides,

Cracking compounds such as cyanides,

Sublimating compounds, such as AIF ₃ , - Melting and evaporation of compounds such as reduced alkali and non-ferrous metals and their compounds, in particular zinc and zinc compounds. Impurities transferred into a gaseous phase are advantageously washed out with a liquid, in particular water. A washing out of gaseous compounds is advantageously carried out spatially separated from the reactor space, for example in a gas scrubber, such as a sprinkler tower, which is connected to the reactor space.

The object of the present invention is further achieved with the features of the reactor according to claim 22. Advantageous developments are specified in the dependent claims 23 to 33. The reactor has induction coils which are suitable for directly heating the bulk material inductively.

Advantageously, the induction coils are suitable for setting a predetermined temperature gradient in the radial and / or axial direction of the reactor. A temperature gradient can be used selectively to control the inventive method.

Advantageously, the induction coils are suitable for heating the bulk material without temperature gradients or with a low temperature gradient. In particular, a radial temperature gradient is possible which is less than 100 K / m, in particular less than 50 K / m, in particular less than 30 K / m.

Advantageously, the reactor has a high-temperature-resistant inner wall into which the induction fields generated by the induction coils at the frequencies used for heating the bulk material do not or at least hardly couple. This reduces the temperature load on the inner wall and significantly increases their life expectancy compared to conventional heaters. The inner wall may have a lining containing at least one of carbon, oxidic refractory, non-oxidic refractories and chamotte. Advantageously, the lining has clay-bonded graphite. Despite the high carbon content, clay-bound graphite has such a low electrical conductivity that it can not be heated inductively.

Advantageously, the reactor has a reactor space which has an upper zone, a middle zone and a lower zone in the axial direction, the reactor in particular being designed so that bulk material to be processed in the upper zone can be introduced, the middle zone is provided with the at least partially extending around the reactor induction coil and accumulate in the lower zone slag and / or purified bulk material and can be removed from it. Thus, a continuous process can be carried out with the reactor.

Advantageously, the reactor has a diameter of more than 50 cm in the region of the induction coils in order to achieve the highest possible throughput. Advantageously, the diameter is greater than 1 m, in particular 1 m up to 1, 5 m. Such a large reactor in conjunction with the direct inductive heating according to the invention enables high flow rates. Due to the inductive heating method in combination with low frequencies and coarse grain size of the bulk material, the bulk material heats up much faster than with conventional heating, which enables energy- and cost-efficient processing.

The reactor may be designed to widen conically downwards in the lower zone and / or in a lower region of the middle zone. This facilitates a slipping of bulk material and slag down.

Advantageously, the reactor has an entry lock, such as a cell sluice, over which the reactor can be supplied with bulk material, the entry lock is suitable, an uncontrolled escape of gases to prevent the reactor. Thus, bulk material and additives and any other necessary substances may be added to the reactor space without uncontrolled escape of gases. Furthermore, a gas scrubber connected to the reactor space, such as a sprinkler tower, may be provided, which is suitable for washing out impurities transferred into a gaseous phase with a liquid, such as water. In the gas scrubber gaseous toxic compounds can be liquid bound from the gas phase and condense due to a low temperature in the gas scrubber. Large volumes of gas can be reduced to smaller amounts of liquid. In the gas scrubber, further, in particular chemical, processes can take place. Thus, in a gaseous compound present zinc can be oxidized with steam to zinc oxide and then filtered off.

Advantageously, at least one injection device can be provided in the reactor which is suitable for introducing water and / or water vapor into the reactor space in at least one of the upper, middle and lower zones. As a result, water can be brought directly to the impurities, so that the above-described reactions run faster.

Advantageously, at least one induction coil is cooled. Since the induction fields do not couple into the reactor wall, they are not heated directly and therefore do not need to be actively cooled. However, the reactor wall is advantageously cooled by convection.

Further advantageous embodiments and further developments of the invention will be explained below with reference to a preferred embodiment and an associated figure.

1 shows a schematic representation of a reactor according to the invention. A reactor 1 according to the invention has a reactor space 2 with a diameter of 1.5 m, around which induction coils 3 are arranged, which are suitable at frequencies between 1 and 50 kHz and which contain carbonaceous bulk material 4 present in the reactor space 2 Heat temperatures up to 1800 ° C. The reactor space 2 is surrounded by a high-temperature-resistant lining 5 of a reactor wall 6. In this embodiment, the lining 5 is made of firebricks. However, all other high temperature resistant materials are suitable which do not couple to a field generated by the induction coils 3, such as clay-bonded carbon. The reactor 1 has an upper zone 7, a middle zone 8 and a lower zone 9.

At the upper zone 7, a filling opening 10 is provided, via which bulk material 4, slag formers, flow formers and the like can be introduced into the reactor space 2. In order to prevent the escape of gases from the reactor chamber 2, a rotary feeder is set as an entry lock 1 1 on the filling opening 10.

The induction coils 3 are provided in the central zone 8. In the lower zone 9, a slide 23 is provided, which acts as a breaker for breaking slag and bulk material 4 for their removal.

The upper zone 7 is provided with a connecting piece 13, which connects the reactor space 2 with a sprinkler tower 14, which acts as a gas scrubber 14. In the sprinkler tower 14, at least one water nozzle 15 is provided for injecting water into the sprinkler tower 14. Trapped water 17 can be discharged via a valve 16.

For operation of the reactor 1, bulk material 4, together with, for example, slag from the blast furnace as slag former and flux, is filled into the reactor space 2 via the rotary valve 11. Slag formers, as well as fluxes can also be added as individual components. The bulk material 4 is in this example cathode outbreak from a Aluminiumschmelzelektrolysezelle. The Bulk material 4 is except with chamotte, which was at the outbreak of the cathode from the aluminum smelting electrolysis cell in the bulk material 4, contaminated with metallic aluminum and aluminum compounds, with sodium cyanide and soluble fluorine compounds.

The induction coils 3 heat the contaminated bulk material 4 directly inductively by coupling the induction fields directly into the cathode outbreak. About the heated bulk material 4, the slag and the flux are heated. In the middle zone 8, a liquid slag is formed, into which the aluminum impurities also melt. Due to the flux, the viscosity of the slag is lowered so that the slag flows into the lower zone of the reactor 1. The slag also transports the chamotte. In the lower zone 9, ie outside an effective range of the induction coils 3, the slag cools down. In this example, the slag is additionally cooled by the water cooling 12 and solidifies.

The temperature of 1750 ° C in this example in the middle zone 8, the cyanide and the fluorine compounds are driven out of the bulk material 4 and go into the gas phase, or decompose. As a result of the volumetric expansion and convection, the gaseous impurities pass via the connecting piece 13 into the sprinkling tower 14. Cyanides and fluorine compounds are dissolved by water trickling out of the water nozzle 15 and other gaseous compounds are condensed. As a result, a volume reduction takes place, which still supports a gas flow from the reactor 2 into the sprinkler tower 14, which is shown in FIG. 1 with an arrow 18.

In the reactor chamber 2 20 steam 21 is injected into the upper zone 7 via a nozzle. The water vapor 21 causes in the reactor chamber 2 a pyrohydrolysis of the existing cyanides already from about 700 ° C. In particular, carbon monoxide, nitrogen and hydrogen are formed. Furthermore, the water vapor 21 in the lower zone leads to a quenching of the slag, whereby it is blasted off of the bulk material 4. About the slider 23, the brittle slag is broken and the lower zone 9 taken. Slag and purified bulk material can then be separated by conventional separation methods due to their density difference. The cleaned carbonaceous bulk material can be used, for example, as an additive for building materials, such as cement. The carbon of the bulk material may be used as fuel or for use in, for example, wear liners such as gutters. Washed fluorine compounds in the water 17 of the sprinkling tower 14, which is taken over the valve 16, can also be reused, for example, by returning to an aluminum electrolysis to adjust the ratio of NaF to AIF ₃ in the melt.

In another example, the method according to the invention was simulated in a miniature structure (not shown). The reactor used was a clay-bonded graphite crucible with a diameter of 150 mm and a height of 200 mm. An induction coil operated at 4 kHz heats an amorphous carbon cathode fracture material having an anthracite content of about 60% by weight as a bulk material. The bulk material was heated to 1600 ° C in 45 min. The resulting exhaust gases were sucked off and condensed in a filter unit with rock wool fibers. The fluorine and cyanide contents before and after heating the bulk material were analyzed by wet chemistry and by X-ray fluorescence analysis. Likewise, the bulk material was analyzed before and after heating. A beginning of the evaporation of impurities was observed at approx. 700 ° C. Furthermore, expulsion of NaF, NaCN, Al 2 O ₃ and AIF ₃ from the carbon was found, these compounds found on the surfaces of the bulk material. When CaO and S1O2 were additionally added to the bulk material, one formed

Slag that picked up these compounds and collected at the bottom of the crucible. An eluate of the bulk material contained more than 1 mg / l of cyanide before heating, then less than 0.01 mg / l. Thus, the effectiveness of the process and reactor according to the invention could be clearly demonstrated. All features mentioned in the description, examples and claims may contribute to the invention in any combination. In particular, the slag-forming components can be derived from both the impurities and the added slag-forming agent. Depending on the provenance of the carbonaceous stones and thus of the impurities, if slag-forming constituents are present as impurities, they must no longer be added as slag formers. A treatment can also be carried out without slag formation.

Claims

claims 1 . Process for the treatment of carbonaceous bulk material containing impurities, characterized in that the bulk material is inductively heated directly in a reactor. 2. The method of claim 1, wherein the bulk material comprises at least one bulk material selected from the group consisting of broken cathodes from an aluminum smelting process, broken anodes, broken carbon liners from a steel smelting furnace, a steel blast furnace or other metal smelting furnace, a glass melting furnace, a ceramic smelting furnace, and others contains carbonaceous stones. 3. The method according to claim 1 or 2, characterized in that the impurities contain at least one impurity from the group consisting of cyanides, sulfur, soluble fluorides, and alkali and non-ferrous metals. 4. The method according to one or more of the preceding claims, characterized in that bulk material is used, the over 50 wt .-% a Grain size of over 30 mm has. 5. The method according to one or more of the preceding claims, characterized in that bulk material is used, which has over 50 wt .-% a particle size between 50 and 150 mm. 6. The method according to one or more of the preceding claims, characterized in that the bulk material is obtained by breaking of reprocessed moldings and / or stones with a crusher, such as with a jaw crusher, cone crusher or gyratory crusher. 7. The method according to claim 6, characterized in that the shaped bodies and / or stones are broken before breaking out of a furnace lining, a cathode block or a similar installation situation. 8. The method according to one or more of the preceding claims, characterized in that the impurities contain aluminum in metallic form, as an oxide, as a carbide and / or in another chemical compound. 9. The method according to one or more of the preceding claims, characterized in that the impurities contain iron in metallic form, as an oxide, as a carbide and / or in another chemical compound. 10. The method according to one or more of the preceding claims, characterized in that inductively heated at frequencies between 1 and 50 kHz, in particular between 1 and 10 kHz, in particular between 2 and 5 kHz. 1 1. Method according to one or more of the preceding claims, characterized in that in the reactor maximum temperatures up to 2500 ° C, in particular between 1250 and 1800 ° C, in particular between 1300 and 1750 ° C, in particular between 1450 and 1700 ° C are set. 12. The method according to one or more of the preceding claims, characterized in that at least a portion of the impurities is dissolved in an existing or forming slag. 13. The method according to one or more of the preceding claims, characterized in that in the reactor, a slag images and / or a flux is added. 14. The method according to one or more of the preceding claims, characterized in that in the reactor, a calcium-containing compound, such as CaO, CaCO3 or dolomite, and / or a silicon-containing compound, such as SiO ₂ or a silicate, and / or an iron-containing compound such as an iron oxide or iron ore. 15. The method according to one or more of the preceding claims, characterized in that the slag flows into a lower zone of the reactor and is removed therefrom. 16. The method according to claim 13, characterized in that the slag is at least partially solidified in the lower zone and the lower zone is removed by means of a slide and / or crusher. 17. The method according to one or more of the preceding claims, characterized in that in at least one zone of the reactor, water and / or water vapor is introduced, such as atomized or atomized. 18. The method according to one or more of the preceding claims, characterized in that the slag is separated from the purified carbonaceous bulk material by quenching with water. 19. The method according to one or more of the preceding claims, characterized in that at least a portion of the impurities is converted into a gas phase. 20. The method according to one or more of the preceding claims, characterized in that at least one of the steps  Pyrohydrolytic decomposition of compounds such as cyanides, Cracking compounds such as cyanides, Sublimating compounds, such as AIF ₃ ,  Melting and vaporization of metals and / or compounds, such as reduced alkali and non-ferrous metals and / or compounds thereof, in particular zinc and zinc compounds, is carried out. 21. Method according to one or more of the preceding claims, characterized in that in a gaseous phase transferred impurities with a liquid, in particular water, are washed out. 22. Reactor for carrying out a method according to one or more of claims 1 to 21, characterized in that the reactor has induction coils which are suitable for inductively heating the bulk material. 23. Reactor according to claim 22, characterized in that the induction coils are suitable for setting a predetermined temperature gradient in the radial and / or axial direction of the reactor. 24. Reactor according to claim 22 or 23, characterized in that the induction coils are suitable for heating the bulk material with a radial temperature gradient of less than 100 K / m, in particular less than 50 K / m, in particular less than 30 K / m is. 25. The reactor as claimed in one or more of claims 22 to 24, wherein the reactor has a high-temperature-resistant inner wall into which the induction fields generated by the induction coils for the heating of the bulk material do not or at least barely couple. 26. Reactor according to one or more of claims 22 to 25, characterized in that the inner wall has a lining which at least one Contains material from the group consisting of carbon, oxidic refractories, non-oxidic refractories and chamotte. 27. Reactor according to claim 26, characterized in that the lining comprises clay-bonded graphite. 28. Reactor according to one or more of claims 22 to 27, characterized in that the reactor has a reactor space in the axial direction an upper zone, a middle zone and a lower zone, wherein the reactor is designed in particular such that in the upper zone to be processed bulk material can be introduced, the central zone is provided with at least partially extending around the reactor induction coils and in the lower zone slag and / or purified bulk material accumulate and can be removed from it. 29. Reactor according to one or more of claims 22 to 28, characterized in that the reactor in the region of the induction coils has a diameter of about 50 cm, in particular of more than 1 m, in particular between 1 m and 1, 5 m. 30. Reactor according to one or more of claims 22 to 29, characterized in that the reactor in the lower zone and / or in a lower region of the central zone is formed conically widening downwards. 31. Reactor according to one or more of claims 22 to 30, characterized in that the reactor has an entry lock, such as a rotary valve, via which the reactor can be supplied with bulk material, the entry lock is suitable, an uncontrolled escape of gases to prevent from the reactor. 32. A reactor according to one or more of claims 22 to 31, characterized in that a gas scrubber connected to the reactor space, such as a sprinkler tower, is provided, which is suitable for introducing impurities transferred into a gaseous phase with a liquid, such as water, wash out. 33. Reactor according to one or more of claims 22 to 32, characterized in that at least one injection device is provided which is suitable for introducing water and / or water vapor into the reactor space in at least one of the upper, middle and lower zones. 34. The use of a process according to one or more of claims 1 to 21, in particular with a reactor according to one or more of claims 22 to 33, cleaned carbonaceous bulk material as a fuel or as a material, for example in wear liners, such as in gutters. 35. Use of a process according to one or more of claims 1 to 21, in particular with a reactor according to one or more of claims 22 to 33, incurred slag in building materials, such as cement.