JPH04295507A - Method and device for regenerating waste loaded by harmful matter - Google Patents

Abstract

PURPOSE: To regenerate waste (material to be regenerated) contaminated with pollutants such as industrial dusts, slurries, mill scale, waste sand and the like into reusable materials, by separating the pollutants therefrom or destructing them sufficiently and satisfactorily from viewpoints of technology, economics and in particular ecology. CONSTITUTION: A heated bulk material bed, at least a part of which is a matter to be regenerated, and which is fluidized at least in the region of an upper layer to form a fluidized bed 3 by introducing gas thereinto, is heated on the fluidized bed from above by a heater 10. The heating intensity therein is controllable or adjustable, and the solids temperature on the one hand and the gas temperature prevailing in the gas space 9 above the fluidized bed on the other hand are adjustable. Further, the thermal requirements of the regenerating process and the fluid dynamics requirements of the material system are decoupled from each other for putting these two requirements under control.

Description

[Detailed description of the invention]

[0001] The present invention is particularly useful in ferrous and non-ferrous metallurgy, where industrial dust and sludge, mill scale, old (foundry) sand, etc. generated in filtration equipment, concentrators, purification equipment, etc., are loaded with harmful substances. A method for regenerating recycled waste (=organisms to be recycled), in which a bed of granular material heated from above is fluidized by introducing (fluid) gas into at least the upper region to form a fluidized bed. Regarding.

[0002] The present invention further provides a wall body capable of forming a bed, in which a bed consisting at least partially of regenerated material is formed, and a fluidizing gas introduced into the bed for the purpose of forming a fluidized bed. a fluidizing device for heating the fluidized bed; a heating device for heating the fluidized bed;
The present invention relates to an apparatus for carrying out the method, having an exhaust pipe for leading out combustion gases.

[0003] As is known, wastes of the above type are generated to a wide extent in all possible technological processes;
Previously - and in some cases until recently - it was simply dumped into the dump.

In view of the fact that available dumping space has become scarce (and correspondingly expensive), and especially from an ecological point of view, it is desirable to recycle at least a portion of such "waste" into materials that can be reused again. Taking into account the circumstances where this is hardly worth it, various regeneration methods have recently been developed. However, they are still not as effective as this would be desirable in and of themselves, and in some cases result in considerable environmental burdens, etc.

[0005] A typical example is old sand that is always generated in relatively large quantities in foundries, and the original molding sand contains especially bentonite (= "inorganic old sand") as a molding material.
) and/or organic binders, such as for example and especially phenolic resins or/and furan resins (="organic old sand"). In the case of inorganically bonded molding sand, bentonite, etc., which is a binder, adheres to the surface of the sand particles in the form of a shell due to chamotte formation (oritization), depending on the degree of heat applied during casting; In the case of molding sands with organic binders, their thermal destruction occurs during the casting process, thus resulting in firmly adhered residues of carbon-free decomposition products of the organic binders on the surface of the sand particles. Furthermore, other additives may cause old sand stains, such as black paint or glossy carbon.

Regarding the reclamation of old sand, there are several special pneumatic or mechanical reclamation methods that separate the sand into recyclable material and a waste fraction that is no longer usable - enriched with hazardous substances. or known.

Decontamination of the waste fraction and recovery of the materials still present in the waste fraction are typical tasks of this new method. In some cases, by mechanical or mechanical/pneumatic regeneration, the old sand generated can be recycled to the extent that a waste fraction still containing only trace amounts of material is generated, but this material fraction can be recycled economically. It is impossible to recover it. In such cases, this waste material is particularly finely granular, contains many harmful substances, and must be decontaminated. When decontaminating these substances, complete combustion of the organic substances must be ensured by appropriate residence times in the reactor.

Another problem of this kind is the generation or regeneration of mill scale, which, as is known, is caused by FE and/or FEO and/or FE3 O 4 and FE.
A mixture of 2 O 3 and water and oil, which occurs at various particle sizes (mainly less than 500 μm) and in parts with markedly different oil and water contents, mill scale is generally composed of Zn, Pb and alkali. It contains only relatively small amounts of other impurities such as. In suitably regenerated form, mill scale can be fed back into metallurgical production processes as an extremely valuable raw material.

Such regeneration of mill scales has traditionally used directly heated or indirectly heated rotary tubes, which operate very energetically uneconomically, in which the oil is converted or burned by indirect combustion or swelling. , the water evaporates. In any case, this so-called rotating tube method requires reprocessing of the gas.

Other examples of problems of the type considered here include wastes such as sludge, sludge from wet scouring of furnace equipment, etc., contaminated soil, residues from production processes such as the ink industry, and other hazardous substances. Pasty or (at least partially) liquid substances or various finely divided solids loaded with.

[0011] The object of the present invention is to make it possible to reuse such wastes by sufficiently separating or destroying their hazardous substances in a technically, economically and, in particular, ecologically satisfactory manner. The purpose of the present invention is to provide a method (and a suitable apparatus for carrying out the same) for recycling it into raw materials.

The material system to be regenerated has various physical properties that must be taken into account during material conversion (combustion, drying, etc.) and when the material is moved through a fluidized bed. The solids must be regenerated at different (limit) temperatures, the maximum permissible temperature being determined by the properties of each solid. Similarly, the residence time of the solids in the fluidized bed depends on the solids and their particle structure, up to the desired degree of material conversion.

In other words, it is necessary to generate the required heat of reaction in order to adapt the respective required amount of fluid gas to the flow conditions in the fluidized bed for various solids, without any reaction to heating and vice versa. It would be desirable to have a reactor in which the amount of fuel and combustion air required does not burden the fluidized bed.

[0014] A solution to the method part of the problem is generally provided in that the fluidized bed consisting at least partly of the regenerated material is optionally additionally heated from above, the heating intensity being controllable or adjustable, ie adjustable. - and the solid body temperature on the one hand and the gas temperature prevailing in the gas space above the fluidized bed on the other hand can be adjusted - preferably separately - and in this case - separately - -It is desirable to be able to adjust the amount of fluid gas required to produce optimal fluidization conditions. This is particularly true for very fine-grained recycled materials.

[0015] In this case, as already indicated, the fluidized bed can consist essentially entirely of regenerated material;
Alternatively, in one embodiment of the invention a particulate support material can be included, in the last case the regenerated material is preferably fed to the support material in the lower third of the fluidized bed.

In the case of a process using a support material, the particle size of the support material is preferably such that (at least most of the particles) of the regenerate are present in order to ensure the egress of the regenerate from the support material without reducing the required residence time. larger than the dimensions.

For the same reason, the coarse density of the support material is in this case greater than the coarse density of the regenerated material, in particular and especially through the selection of the relative coarse densities, the residence time of the regenerated material in the support layer during regeneration can be controlled, as it were. Can be adjusted.

[0018] For many regenerants, it has proven particularly desirable for the support material to be at least substantially spherical. In a further embodiment of the invention, the fluidized bed can be at least partly cyclically driven in a manner known per se, and can otherwise be either oxidatively or reductively driven;
In the latter case the exhaust must be reprocessed.

According to a further development of the invention, the fluid gas can consist essentially of air (ie not of fuel), in which case the amount of fluid gas temporarily supplied to the fluidized bed is As long as the amount of fluid gas thus determined is sufficient for the fluidization of the fluidized bed and its flow rate can be adjusted within wide limits in a highly preferred further embodiment of the invention, the oxygen contained therein is The proportion is such that the fuel (eg, oil, hydrocarbon compounds, etc.) contained in the regeneration is (just) sufficient to convert or burn at predetermined time intervals.

Oxygen (in the amount of air supplied) necessary for the conversion of the fuel (eg oil, hydrocarbons, etc.) contained in the regenerated material is necessary to adjust the optimal fluidization state in the fluidized bed. If the amount of air exceeds a certain amount, the very fine particles of regenerated material which are generally present in this case will coagulate to a suitable particle size when water is added. This prevents excessive temperatures from building up in the fluidized bed and at the same time maintains the required residence time of the fine particles in the fluidized bed by the time required to dissolve the agglomerates. In such cases, the fluidized bed is preferably formed from the coarse particles contained in the material to be regenerated.

It may be desirable to add limestone or the like to the fluidized bed in a manner known per se in order to generate the sulfur content of the regenerated material. It may be pointed out that when generating the heat of reaction, the addition of air is adjusted in stages, preferably so that substantially no significant formation of NOx occurs.

According to the invention, the fluidized bed is most preferably heated from above, preferably using a high-speed burner, with the fuel fraction already present in the material to be regenerated being used as auxiliary fuel. It has been found that gaseous fuels (exceeding

[0023] The fluidized bed preferably has a temperature of about 750 to 950
Maintained at a steady temperature of °C. According to preferred embodiments of the invention, the temperature in the solid material, on the one hand, and the temperature in the gas space above the fluidized bed, on the other hand, as well as the residence time of the regenerated material remaining in the fluidized bed, vary. can be adjusted to

It is also generally desirable for the flow rate of the fluidized bed to be adjustable within wide limits, in order to be able to optimally adapt the operating conditions to the particular requirements of the regenerated material. Furthermore, it may be desirable to separate the solids in a separator or the like provided downstream of the fluidized bed, and in this case, it may be highly desirable to feed a portion of the separated solids into the fluidized bed.

In the case of mill scales, according to the invention, they are placed in a hot, heated fluidized bed with a high heat capacity, which in this use case is made of a (separate) support material or an appropriately coarse mill scale. In operation, fine mill scale is desirably discharged through the head and coarse scale can be discharged at the bottom of the fluidized bed. Regardless of whether coarse mill scale or, for example, steel grit is used in this case, the moisture contained in the regenerated mill scale spontaneously evaporates when it is charged into the fluidized bed, whereby/this causes the mill scale to At the same time, the oil contained therein is finely atomized, and the oil adhering to the mill scale is naturally vaporized, and the oil is completely oxidized by the fluidizing gas air (or oxygen) constantly supplied to the fluidized bed.

In the case of wet beneficiation sludge, contaminated soil, residues from the ink manufacturing industry, etc., they can also be treated in fluidized beds with or without special support materials, in which case generally so-called gas spaces above the fluidized bed Re-combustion occurs within the
Very fine flue dust particles are completely decontaminated.

The same applies to the regeneration according to the invention of pasty or liquid substances, in which the process is of course always carried out in a fluidized bed with a supporting material, and in these cases also the organic components are more or less naturally and completely recovered. (“combustion”) and the sulfur content can optionally be combined by the addition of limestone.

Preferred embodiments of the invention are specified in the dependent claims. The present invention will be further described below with reference to one embodiment with reference to the drawings. The drawings relate to the decontamination according to the invention of waste from mechanical sand reclamation, which is currently of high value.

The drawing shows in a schematic diagram a hopper 1 in which waste is collected. The waste is fed to a humidification/agglomeration device 2 and the agglomerates formed there are charged to a fluidized bed furnace 3.

Because the heat transfer is so rapid (and the mixing in the fluidized bed is so good), the agglomerate has an outer layer of about 800 ~
It is rapidly heated to an operating temperature of 850° C. and the agglomerated harmful substances are completely converted by atmospheric oxygen. As a result of the movement of the material through the fluidized bed, the aggregates are slowly consumed.

Finely divided solids are discharged from this fluidized bed via the head. This solid is separated in a separator 6 by means of a gas stream in order to protect the downstream heat exchanger 5 from wear and tear. The solids leave the fluidized bed via the head or side discharge pipe 7a or 7b, the discharge pipe 7b being only occasionally used to discharge non-flowable material.

The flue gas is cooled in the heat exchanger 5 while preheating the flowing air. The solids pass through a cooler 8 to cool the solids discharged through the head and separated in the separator and the solids discharged laterally from the fluidized bed above the fluidized bed 3 in the fluidized bed furnace 9. A high-speed burner 10 whose calorific value can be controlled is arranged, and its flame port 11 is connected to a fluidized bed furnace 9.
It is adjustable with respect to the wall 12 and with respect to the surface 13 of the fluidized bed 3, and the high-speed burner 10 is arranged substantially centrally and is held in a holder (not shown) in the roof of the fluidized bed. .

[Brief explanation of drawings]

FIG. 1: The drawing relates to the decontamination according to the invention of waste from mechanical sand reclamation, which is currently of high value.

[Explanation of symbols]

1 Hopper 2 Humidification agglomeration device 3. Fluidized bed 4 Fluidized bed surface 5 Heat exchanger 6 Separator 7a, 7b Discharge pipe 8. Solids cooler 9 Entire fluidized bed furnace 10 Burner 11 Flame mouth 12 Wall of fluidized bed furnace ■Gas reprocessing, rapid cooling, dust removal

Claims (41)

[Claims] [Claim 1] Industrial dust, sludge, mill scale,
Wastes loaded with harmful substances such as old sand (=recycled organisms)
A method for regenerating a heated granular material bed by introducing a (fluid) gas at least in the upper layer region to fluidize it to form a fluidized bed. The bed is heated from above, the heating intensity being controllable or adjustable, the solids temperature on the one hand and the gas temperature prevailing in the gas space above the fluidized bed on the other hand being adjustable, and the regeneration process A method characterized in that the thermal requirements from the side of the material system can be controlled separately from the fluidics requirements from the material system side. 2. Process according to claim 1, characterized in that the solid body temperature and the gas temperature are separately adjustable. 3. Method according to claim 1, characterized in that the heating intensity is adjustable independently of the fluidic requirements of the material system. 4. Method according to claim 1, characterized in that the movement of the substance can be adjusted independently of heating. 5. Process according to claim 1, characterized in that the fluidized bed consists essentially entirely of regenerated material. 6. Process according to claim 1, characterized in that the fluidized bed contains a particulate support material. 7. The method according to claim 6, characterized in that the material to be regenerated is fed into the fluidized bed from above. 8. Process according to claim 1, characterized in that the material to be regenerated is fed to the lower third of the fluidized bed. 9. A method according to claim 6, characterized in that the extremely fine-grained material to be regenerated is humidified and agglomerated before being charged into the fluidized bed. 10. Claim 6, characterized in that the particle size of the supporting material is (at least mostly) larger than the particle size of the material to be recycled.
10. The method according to any one or more of 9 to 9. 11. The method according to claim 6, wherein the coarse density of the support material is greater than the coarse density of the material to be recycled. 12. Process according to claim 6, characterized in that the support material is substantially spherical. 13. A method as claimed in claim 1, characterized in that the fluidized bed is at least partially cyclically driven. 14. A method as claimed in claim 1, characterized in that the fluidized bed is oxidatively driven. 15. The method according to claim 1, wherein the fluidized bed is driven to reduce and the exhaust gas is re-combusted. 16. The fluid gas substantially (simply) consists of air and/or inert gas, and the amount of fluid gas temporarily supplied to the fluidized bed is such that the oxygen contained therein is equal to or less than the fuel contained in the regenerated material. (as long as the amount of fluid gas thus determined is sufficient to fluidize the fluidized bed). or the method described in one or more of the following paragraphs. 17. Any one of the preceding claims, characterized in that the flow rate of the fluidized bed is adjustable within wide limits.
How to describe a term or multiple terms. 18. Any one of the preceding claims, characterized in that the temperature(s) are adjusted or the combustion air is supplied in stages so that substantially no significant formation of NOx occurs. Method for writing multiple terms. 19. Process according to claim 1, characterized in that the fluidized bed is heated with a gaseous fuel as auxiliary fuel. 20. Process according to claim 1, characterized in that air or oxygen is used as the oxidizing means for the combustible gas. 21. Any one of the preceding claims characterized in that a plasma burner (instead of a gas burner) is used.
How to describe a term or multiple terms. 22. Process according to claim 1, characterized in that the fluidized bed is maintained at a constant temperature of about 700-950°C. 23. Process according to claim 1, characterized in that at least some of the solids are returned to the fluidized bed in a separator provided downstream of the fluidized bed. 24. A method according to claim 1, characterized in that the fluidized air is preheated with the exhaust heat of the fluidized bed. 25. A method according to claim 1, characterized in that the exhaust gas at about 450-150° C. is quenched with water. 26. Process according to claim 1, characterized in that the heating is operated near-stoichiometrically. 27. A wall body capable of forming a bed, in which a bed at least partially composed of regenerated material is formed, and a fluidization device for introducing a fluid gas into the bed for the purpose of forming a fluidized bed. , a heating device for heating a fluidized bed, and an exhaust pipe for discharging combustion gas, and waste (=recycled organisms) loaded with the harmful substances described in any one or more of the preceding claims. In the regeneration equipment, the heating device is a fluidized bed (3)
It is configured as a high-speed burner (10) located higher up, with its flame port (11) and wall (12) or fluidized bed (3).
A device characterized in that the distance to the surface (4) is adjustable. [Claim 28] High speed burner or plasma burner (1
0) or whose flame port (11) is substantially a fluidized bed furnace (9)
The wall (12) or the fluidized bed (3) held thereby
28. The device of claim 27, wherein the device is located at the center of the . 29. The apparatus according to claim 27 or 28, characterized in that an afterburner or afterburning chamber is arranged in the exhaust pipe of the fluidized bed furnace (9). 30. The device according to claim 29, further comprising a flue gas reprocessing device disposed in the exhaust pipe. 31. Device according to claim 30, characterized in that the flue gas reprocessing device comprises a separator. 32. Device according to claim 30 or 31, characterized in that the flue gas reprocessing device comprises a water quench stage. 33. Device according to claim 29, characterized in that the flue gas reprocessing device has a filter. 34. Apparatus according to claim 33, characterized in that the filter is a cloth filter. 35. In the bottom region of the bed formed by the wall (12), a preferably substantially spherical granular bed is formed, the grain size of which is substantially larger than the grain size of the material to be recycled. 35. Device according to one or more of claims 27 to 34, characterized in that: 36. The apparatus of claim 35, wherein the coarse density of the bed is greater than the coarse density of the material to be regenerated. Claim 37: A wall forming or holding a floor (12
37. Device according to one or more of claims 27 to 36, characterized in that the drain tube) has at least one closable side discharge pipe and/or optionally a closable bottom discharge pipe. 38. Apparatus according to claim 27, characterized by a plurality of nozzles extending into the area of the fluidized bed to be formed. 39. Claim 38, characterized in that the immersion depth of the nozzles is preferably individually variable or adjustable.
The device described. 40. Device according to one or more of claims 27 to 39, characterized by a control device that can optionally control or adjust the amount of fluid gas temporarily supplied. 41. Switching the non-circulating mode of operation of the fluidized bed at least partially into a circulating mode of operation by means of a control or regulating device which is controllable/adjustable by the temporary amount of coarse particles separated in the separator. 41. Device according to any one of claims 27 to 40, characterized in that it is capable of: