ZA200309340B

ZA200309340B - Method and device for treating particulate material.

Info

Publication number: ZA200309340B
Application number: ZA200309340A
Authority: ZA
Inventors: Michael Nagl; Johannes Schenk; Albert Zschetzsche
Original assignee: Voest Alpine Ind Anlagen
Priority date: 2001-06-19
Filing date: 2003-12-01
Publication date: 2004-12-01
Also published as: AT410181B; UA79933C2; ATA9482001A

Description

The invention relates to a process for treating, preferably for reducing, material in particle form in at least one fluidization zone at elevated temperature, in particular for reducing fine ore, the particulate i material being held in the fluidization zone by a treatment gas which flows upward from below, and material in fine particle form which is discharged from the fluidization zone with the treatment gas being separated out of the treatment gas in a deposition zone, the following steps being carried out in the deposition zone: feeding the stream of treatment gas and discharged material in fine particle form to a separating device, separating the finely particulate material from the treatment gas, the treatment gas being extracted from the separating device as off-gas, and removing the separated finely particulate material from the separating device, and to an apparatus for carrying out the process.

In fluidized-bed systems, the separation of material in fine particle form, i.e. fine dust, which is discharged or entrained from the fluidization zone with the treatment gas, is of considerable importance.

It is desirable for the fine dust to be separated from the treatment gas as completely as possible, in order on the one hand to avoid loss of material and in order on the other hand to avoid caking originating from the fine dust carried in the treatment gas in a further process, in which the off-gas extracted from the separating device 1s generally once again used as a - 35 treatment gas.

Fine dust has poor flow properties in particular in the hot state and tends to cause blockages and caking in cyclone outlets and inlets. In extreme cases, fine-dust return lines may even become blocked up.

Therefore, the object of the present invention 1s to provide a process which avoids the problems outlined above. In particular, it is intended to ‘reduce or prevent caking and blockages in the separating device and lines which supply the separating device or lead away from it.

As claimed in the invention, this object is achieved by virtue of the fact that a coarse-grained material 1s introduced into the deposition zone in addition to the stream of treatment gas and discharged finely particulate material.

The addition of coarse-grained material to the deposition zone improves the flow properties of the fine dust, i.e. reduces its caking tendency. It is even possible to reduce the extent of existing caking on account of a cleaning effect which occurs during the addition of the coarse-grained material.

As claimed in an advantageous embodiment of the process as claimed in the invention, coarse-grained material whose temperature is at least 200°C below the temperature of the treatment gas and that of the finely particulate material is used.

Since part of the caking tendency originates from the high temperature of the treatment gas and therefore of the finely particulate material, it is advantageous if the temperature of the coarse-grained material is well below the temperature of the finely particulate material.

In this case, it is particularly preferable for the temperature of the «coarse-grained material to De substantially ambient temperature.

This allows the maximum possible temperature difference between finely particulate material and coarse-grained material to be utilized, in order to improve the flow properties of the finely particulate material.

As claimed in a further embodiment of the process as claimed in the invention, the coarse-grained material is introduced into the stream of the treatment gas which is to be fed to the separating device.

Furthermore, it is advantageous 1f, in addition or as an alternative, coarse-grained material is introduced into the separating device itself.

Furthermore, it is advantageous if, in addition or as an alternative to the embodiments described above, coarse-grained material is added to the finely particulate material which is removed from the separating device.

This has proven advantageous in particular if the separated finely particulate material is fed to a further fluidization zone.

The location where the coarse-grained material is added can be varied as claimed in the requirements of the process, although simultaneous addition of coarse- grained material at all the positions listed above is also possible.

In particular, it is also possible to vary the addition of the coarse-grained material in terms of time, for example for it to be added continuously or intermittently. 2s claimed in a preferred variant, the coarse-grained material is added pneumatically with the aid of a carrier gas.

In this case, it is particularly advantageous if the carrier gas 1s chemically inert with respect to the treatment gas or is substantially to completely identical to the treatment gas. For example, if the treatment gas is a reduction gas which contains CO and

H,, the carrier gas is preferably likewise a reduction gas which contains CO and H;, particularly preferably a gas of this type having the same composition. However, at the least the carrier gas used is an inert gas, such as for example nitrogen.

The pneumatic addition of the coarse-grained material makes its abrasive action particularly pronounced, meaning that it is not necessary for coarse-grained material to be added continuously, and periodic addition, for example pulsed addition, is sufficient.

As claimed in a further feature of the process as claimed in the invention, the coarse-grained material is added using the force of gravity.

In this case, the coarse-grained material is, for example, introduced into a solids lock and then introduced into the separating device under the force of gravity.

Of course, it is advantageous 1f the coarse-grained material has a substantially similar composition to the particulate material which has been treated in the fluidization zone or if the coarse-grained material has a composition which allows the coarse-grained material to be processed further, in a process step which follows the fluidization zone, together with the particulate material.

Therefore, in the case of the reduction of fine ore, the coarse-grained material is advantageously formed by ore and/or additives, such as lime, dolomite or MgO.

The invention also relates to an apparatus having at least one fluidized-bed reactor with a lower part, which accommodates the fluidization zone, and with an upper part, which is connected to a deposition device, the deposition device being formed by a separating device, preferably a cyclone, in which material in fine ) particle form can be separated from the treatment gas, a means for feeding treatment gas and material in fine particle form into the separating device, a treatment- gas discharge line, which leads out of the separating device, and a solids discharge line, which leads out of the separating device.

The object of this aspect of the invention is to provide an apparatus in which caking and blockages on or in the deposition device are avoided or reduced.

As claimed in the invention, this object is achieved by virtue of the fact that the deposition device is provided with a means for feeding coarse-grained material into the deposition device.

The means for feeding treatment gas and finely particulate material into the separating device is designed as a function of the spatial arrangement of the fluidized-bed reactor and of the deposition device and of the spatial distance between them and comprises, for example, an inlet opening (in the case of an internally located cyclone), a pipeline (in the case of an externally located cyclone a short distance away) or a pneumatic conveying line (if there is a relatively great distance between fluidized-bed reactor and cyclone).

The separating device 1s preferably designed as a cyclone, since this is by far the most common application.

As claimed in an expedient embodiment, the means for supplying coarse-grained material 1s designed as a lance which opens out into the interior of the separating device in such a manner that coarse-grained material can be introduced into the interior of the separating device. i As claimed in a further embodiment of the apparatus as claimed in the invention, the means for supplying coarse-grained material is connected to the means for supplying treatment gas in such a manner that coarse- grained material can be introduced into the stream of finely particulate material which is entrained with the treatment gas.

Another possible way of making it possible to introduce coarse-grained material into the separating device is for at least one additional inlet opening, through which the coarse-grained material can be introduced into the separating device by the means for supplying coarse-grained material, being provided on the separating device.

In those cases in which the separating device is a cyclone, an additional inlet opening 1s advantageously arranged in such a manner that coarse-grained material can be introduced into the cyclone substantially tangentially by the means for supplying coarse-grained material.

A tangential supply of the coarse-grained material results in the minimum interference with the deposition efficiency of the cyclone.

As claimed in a further advantageous embodiment, an additional inlet opening 1s arranged in such a manner that coarse-grained material can be introduced into the separating device from above by the means for supplying coarse-grained material.

A further configuration of the apparatus as claimed in the invention consists in the means for supplying coarse-grained material being connected to the solids discharge line in such a manner that coarse-grained material can be introduced into the stream ‘of finely particulate material which has been separated out in the separating device.

This reduces or prevents caking and deposits in the solids discharge line which connects the separating device to downstream parts of the installation, e.g. a further fluidized-bed reactor.

The apparatus as claimed in the invention may in principle be equipped with either an internal separating device or an external separating device, with the solids discharge line from an external separating device leading back either into the same fluidized-bed reactor (circulating fluidized bed) or into a further fluidized-bed reactor.

In the case of an internal separating device, the treatment gas discharge line leads to outside the fluidized-bed reactor, and the solids discharge line opens out into the fluidization zone of the sane fluidized-bed reactor.

As claimed in one feature of the apparatus as claimed in the invention, the means for supplying coarse- grained material is designed as a pneumatic feed device.

The invention also relates to an apparatus and a process for cleaning dust-laden ges in a separation chamber, in particular a cyclone, preferably by means of centrifugal-force deposition, the dust-laden gas flowing into the separation chamber via an opening, and the at least partially cleaned gas being discharged again, preferably flowing out, from the separation chamber via a line, for example via a submerged pipe. }

Furthermore, the invention relates to a process for reducing the amount of gas which flows out of a separation chamber, in particular a cyclone, in which solids are separated out of a gas, preferably by means of centrifugal-force deposition, and the at least partially cleaned gas 1s removed via at least one removal line, and the separation chamber, as a result of at least partial blockage by the deposited solids, has a deposition capacity which is lowered, in particular compared to standard operation.

Centrifugal-force deposition means is used as a general term to encompass equipment in which centrifugal force is utilized to deposit solids, for example dust, out of gases. In operational practice, in particular at high operating temperatures, i.e. during the cleaning of hot dust-containing off-gas, the occurrence of caking 1s observed in the «cyclone. Caking of this type, in particular at the underflow of the centrifugal-force deposition means, cannot always be prevented altogether, and consequently suitable measures have to be taken in the event of caking occurring, with the subsequent adverse effect on operation.

If the caking causes the centrifugal-force deposition means to become blocked and therefore the deposition capacity to become unsatisfactory, it is customary to block off the line for removing the gas, which 1s now only being insufficiently cleaned in the deposition means, using a suitable shut-off device, which is preferably of mechanical design. This makes it possible to prevent the insufficiently cleaned gas from escaping into downstream installations or into the environment.

Both these possibilities would have corresponding drawbacks.

However, in particular at high temperatures, mechanical shut-off devices of this type are susceptible to faults and require regular and intensive maintenance. Finally, corresponding functional designs of shut-off devices of this type are also very expensive to procure.

The present invention is therefore based on the object - of overcoming the drawbacks of the prior art and developing a simple and economic process in accordance with the preamble of claims 20 and 24, and a suitable apparatus, preferably for carrying out said process, in accordance with claim 27.

This object is achieved in accordance with the process of the invention as described in the characterizing clauses of claims 20 and 24, and in accordance with the apparatus of the invention as described in the characterizing clause of claim 27.

The embodiments of the invention are generally based, by way of example, on a centrifugal-force deposition : means, in particular a cyclone, but do not in any way restrict the use of the processes as claimed in the invention or the apparatus as claimed in the invention to these specific designs.

Feeding the coarse bulk material into the separation chamber causes caking and/or encrustation which forms in the separation chamber and/or in the region of the separation chamber, for example at the transition from the cone to the, preferably cylindrical, material outlet line of a cyclone, to be prevented or reduced and/or causes caking which has already formed to be effectively at least partially removed.

As claimed in a particular embodiment of the invention, the caking is abraded and/or knocked off, in particular by mechanical action.

As claimed in a particular embodiment of the process as claimed in the invention, coarse bulk material is fed into the separation chamber in a predetermined grain size, composition and/or amount at which the occurrence of caking in the separation chamber is reduced and/or caking which has already occurred is at least partially removed.

The coarse bulk material is preferably introduced via the line for discharging the at least partially cleaned gas.

As claimed in a further embodiment, the coarse bulk material is introduced directly into the separation chamber.

As claimed in another embodiment of the process as claimed in the invention, the coarse bulk material is fed into the separation chamber together with the dust- laden gas which is to be cleaned.

For the «cleaning action of the bulk material, in particular in the separation chamber and/or the material outlet line, to be successful, it is essential for the bulk-material particles to have a sufficient kinetic energy. Accordingly, for example when the bulk material is supplied together with the dust-laden gas, a suitable way of allowing them to take up kinetic energy, preferably a suitable drop, has to be provided in the centrifugal-force deposition means.

As claimed in one embodiment of the process as claimed in the invention, the coarse bulk material has a mean grain size which at least partially prevents undesired discharge of the coarse bulk material from the separation chamber, in particular via the line for } removing the at least partially cleaned gas.

As claimed in one embodiment of the process as claimed in the invention, the coarse bulk material, before being introduced into the separation chamber, is prepared such that the coarse bulk material has a mean grain size which reduces, in particular prevents, the discharge of the bulk material via the ‘line for removing the at least partially cleaned gas. The grain size required is in this case dependent on the construction of the separation chamber and on the flow conditions in the separation chamber and/or the line for removing the at least partially cleaned gas.

When the material outlet is laid in a separation chamber, in particular a cyclone, it 1s filled with the deposited solids up to just below the line for removing the at least partially treated gas, in particular the submerged pipe, so that the solids-laden gas can flow from the inlet to the submerged pipe and conveys the solids to be deposited away through the line, in 20 .particular the submerged pipe. Although this therefore eliminates the function of the cyclone, the gas stream from which dust has not been removed does not come to a standstill and may even - depending on the flow resistances - rise compared to, for example, separation chambers functioning in parallel.

Therefore, it is recommended to block off the adversely affected cyclone.

As claimed in the prior art, mechanical slides would be installed in the gas-removing lines. Given the conditions which are present, such slides are very expensive, complex and susceptible to faults, and depending on the guidance of the pipes also considerably increase the size of the built-up space.

As claimed in a preferred embodiment of the invention, this problem can be solved considerably more neatly by a material-introduction connection piece, for example with a nominal width of approx. 200 mm, which is preferably closed off by a ball valve, preferably being arranged in the gas line which leads out. This ball valve can be designed for low temperatures by having a gentle purging flow and generally functions without faults. :

As claimed in a particular embodiment, if a cyclone has become blocked, a vessel with a tap is fitted onto the ball valve and flanged into place. This vessel is filled with relatively coarse bulk material - e.g. screened ore. The ball valve 1s then opened and the bulk material fills the space which remains up to the submerged pipe, as well as part of the submerged pipe itself. The dust-laden gas would then have to flow through this bulk material, so that the flow comes to a standstill in no time. In this case, as claimed in an additional feature of the invention, the initial flow of the dust-laden gas, on account of the flow effect, causes the spaces within the coarse bulk material to be filled up by the fine dust which is carried, so that ultimately the bulk material bed is at least partially sealed off. This effectively blocks off the cyclone.

As claimed in one embodiment of the process as claimed in the invention, the gas in the separation chamber is at least partially prevented from leaving the separation chamber via the line for removing the at least partially treated gas by a bed of bulk material which is caused by the introduction of the coarse bulk material.

As claimed in one embodiment of the process as claimed in the invention, the coarse bulk material has a mean grain diameter which at least partially prevents discharge via the gas flow out of the separation chamber, preferably out of the separation chamber itself, in particular via the line for removing the at least partially cleaned gas.

As claimed in one embodiment of the process as claimed in the invention, the coarse bulk material, before it is introduced into the separation chamber, is treated in such a manner that the coarse bulk material has a mean grain diameter which reduces, in particular prevents, the discharge of the bulk material via the line for removing the at least partially cleaned gas.

The grain size required is in this case dependent on the construction of the separation chamber and on the flow conditions in the separation chamber and/or the line for removing the at least partially cleaned gas.

The invention is also characterized by an apparatus as claimed in claim 27, preferably for carrying out the process as claimed in one or more of claims 20 to 23 and/or 24 to 26.

A filling connection piece in this case preferably represents a device via which the coarse bulk material can be introduced into the line for removing the gas which has been at least partially cleaned in the separation chamber in normal operation.

As claimed in a particular embodiment of the apparatus as claimed in the invention, a filter and/or a grate, by means of which the coarse bulk material can be separated from the deposited dusts, is provided downstream of the separation chamber, in particular beneath the separation chamber.

As claimed in a further embodiment of the apparatus as claimed in the invention, a device for extracting the coarse bulk material, 1f appropriate from the filter and/or the grate, is arranged downstream of the separation chamber, in particular beneath the separation chamber.

As claimed in a further embodiment of the apparatus as claimed in the invention, the coarse bulk material can be recycled and, for example in the manner described, introduced back into the separation chamber and/or the line for removing the at least partially cleaned gas.

As claimed in an additional embodiment of the apparatus as claimed in the invention, the filling connection piece is provided as part of a device for the metered supply of the coarse bulk material, the device also having a controllable lock or a controllable star feeder or another component for the metered supply of the bulk material.

As claimed in a particular embodiment of the apparatus as claimed in the invention, the device for controlled supply has a vessel which can be coupled to the filling connection piece.

As claimed in various embodiments of the apparatus as claimed in the invention, the following devices are provided for the, in particular controlled, supply of coarse bulk material: eo line having a lock, in particular a star feeder, which allows the bulk material to be supplied either continuously or batchwise e vessel which is provided either in a fixed position or variably (such that it «can be attached and removed), once again with a corresponding lock, in particular a star feeder.

The processes as claimed in the invention and the apparatus as claimed in the invention are particularly preferably suitable for use in metallurgy, since this technology often involves working with dust-laden, hot gases which have to be cleaned. The processes described and the apparatus as claimed in the invention are particularly preferably used to clean the reduction gas, in particular from a fluidized-bed process, preferably used in metallurgical reduction technology.

The processes as claimed in the invention and the apparatus as claimed in the invention are also suitable for use in particular in installations and processes used in the nonferrous metals industry or the non-metals industry, for example in cement production and/or cement processing.

The processes as claimed in the invention and the apparatuses as claimed in the invention are explained in more detail below, by way of example with reference to a number of non-restrictive drawings, in which:

Fig. 1 shows an embodiment of the process as claimed in the invention for treating, preferably for reducing, material in particular form, as well as a suitable apparatus for carrying out the process

Fig. 2 shows a further embodiment of the process as claimed in the invention for treating, preferably for reducing, material in particle form, as well as a suitable apparatus for carrying out the process

Fig. 3 shows a vertical cross section through a deposition device

Fig. 4A and 4B show a deposition device in vertical section and horizontal section

Fig. 5 shows an exemplary embodiment of a process and an apparatus for cleaning a dust-laden gas

Fig. 6 shows an exemplary embodiment of a process and an apparatus for cleaning a dust-laden gas, as well as a way of introducing the coarse bulk material

Fig. 7 shows a process for minimizing the amount of gas which flows out of a separation chamber for separating solids out of gases

Fig. 1 shows a fluidized-bed reactor 1, the lower part of which includes a fluidization zone 2. Treatment gas is fed to the fluidized-bed reactor 1 from below - through a treatment-gas feed line 3. The treatment gas is distributed uniformly via a gas-distribution base 4, which may be designed, for example, as a nozzle grate, with the material in particle form also being fluidized in the fluidization zone 2.

The reactor 1 is provided with feed and discharge lines 5, 6 for particulate material and with a discharge line 7 which simultaneously forms the means 7 for feeding treatment gas and material in fine particle form into the separating device.

The separating device 8 is designed as a cyclone and has a treatment-gas discharge line 9 and a solids discharge line 10. The solids discharge line 10 opens out into the fluidized-bed reactor 1 or into the fluidization zone 2.

Arrows 11, 12, 13, 14, 15 diagrammatically depict a plurality of means for feeding coarse-grained material into the deposition device, or the locations where these means may be arranged.

Coarse-grained material is introduced into the treatment-gas supply 7 by the means 11, and coarse- grained material is introduced into the cyclone by the means 12, 13, 14, the means 12 partially passing through the treatment-gas discharge line 9 and opening out into the interior of the cyclone.

Coarse-grained material 1s introduced directly into the interior of the cyclone via the means 13, 14,

specifically from above through an additional introduction opening (not shown) in the case of 13 and substantially tangentially with respect to the cyclone 8 in the case of 14.

Coarse-grained material is introduced into the solids discharge line 10, which leads away from the cyclone 8, through the means 15.

Each of the means 11, 12, 13, 14, 15 is preferably designed as a pneumatic feed device, although addition under the force of gravity is equally possible. :

Fig. 2 shows a fluidized-bed reactor 1', the lower part of which includes a fluidization zone 2. Treatment gas is fed to the fluidized-bed reactor 1' from below through a treatment gas feed line 3. The treatment gas is distributed uniformly via a gas-distribution base 4, which may be designed, for example, as a nozzle grate, with the particulate material also being fluidized in the fluidization zone 2.

The reactor 1 is equipped with feed and discharge lines 5, 6 for particulate material. Instead of an external cyclone 8, the fluidized-bed reactor 1' 1s equipped with an internal cyclone 16, in which the means 17 for supplying treatment gas is formed by an inlet opening 17 and from which a solids discharge line 18 leads away, opening out into the fluidization zone 2.

A treatment-gas discharge line 19, through which treatment gas is carried away from the fluidized-bed reactor 1', leads away from the cyclone 16.

Arrows 12, 13 diagrammatically indicate means 12, 13 for feeding coarse-grained material into the cyclone 16, the means 12 partially passing through the treatment-gas discharge line 19, and the means 13 opening into the interior of the cyclone from above through an additional introduction opening (not shown).

Fig. 3 illustrates a horizontal cross section through a cyclone 8. Both the treatment-gas feed 7 and the means 14 for supplying coarse-grained material "open out approximately tangentially - with respect to the cyclone 8 - and horizontally into the cyclone.

Fig. 4A shows a vertical «cross section through a cyclone 8 with treatment-gas discharge line 9 and solids discharge line 10. A means 17 for supplying treatment gas is designed as a laterally arranged inlet opening.

A means 13 for supplying coarse-grained material leads obliquely from above through the cyclone cover.

Fig. 4B shows the same cyclone 8 as Fig. 4A in a horizontal cross section. It can be seen that both the treatment-gas feed 7 and the means 13 for supplying coarse-grained material open substantially tangentially into the cyclone 8.

In accordance with Fig. 5, dust-laden gas is introduced via an inlet 20 into a cyclone 21, in which dust is at least partially removed from it. The cleaned gas is discharged from the separation chamber via a submerged pipe 22. The residues which have been separated off, in particular the dust which has been separated off, 1s discharged via an outlet pipe 23 for further utilization. Particularly in the case of hot dust- containing gas, the deposited dust tends to form caking 24, which as claimed in one embodiment of the process as claimed in the invention is removed by coarse bulk material 25 which is introduced, for example, via the submerged pipe.

Fig. 6 shows a detailed view of the introduction of the coarse bulk material into the submerged pipe 22 in ] accordance with a particular embodiment of the process as claimed in the invention. Accordingly, the cleaned gas is discharged from the separation chamber 21 via a gas line 26. A connection piece 27 opens out into the gas line 26 above the separation chamber, and the coarse bulk material is introduced through this connection piece, in particular via a ball valve 28.

Finally, Fig. 7 shows the situation in which the separation chamber 21 has become blocked by the hot dust 24° and it is no longer possible for any significant amounts of the dust to be removed. Of course, in this situation, gas, which has now not been cleaned, could continue to flow out of the separation chamber into the submerged pipe 22, having an adverse effect on the further process. To prevent this, as claimed in the invention it is proposed for coarse bulk material 25 to be introduced into the submerged pipe and in this way to close off the submerged pipe or the cyclone in a substantially gastight manner.

Claims

Patent Claims

1. Process for treating material in particle form in at least one fluidization zone at elevated temperature, the particulate material being held in the fluidization zone by a treatment gas which flows upwards from below, and material in fine particle form which is . discharged from the fluidization zone with the treatment gas being separated out of the treatment gas in a deposition zone, the following steps being carried out in the deposition zone: feeding the stream of treatment gas and discharged material in fine particle form to a separating device, separating the finely particulate material from the treatment gas, the treatment gas being extracted from .the separating device as off-gas, and removing the separated finely particulate material from the separating device, characterized in that a coarse- grained material, which is separated off together with the finely particulate material, is introduced into the deposition zone in addition to the stream of treatment gas and discharged finely particulate material, and in that the material which has been separated off is returned to the fluidization zone and that the temperature of the coarse-grained material is at least 200°C below the temperature of the treatment gas and that of the finely particulate material.

2. Process according to Claim 1, characterized in that the process is used for reducing fine ore.

3. Process according to either one of Claims 1 or 2,characterized in that the temperature of the coarse- grained material is substantially ambient temperature. Amended sheet 8/12/2004

4. Process according to any one of Claims 1 to 3, characterized in that coarse-grained material is introduced into the stream of the finely particulate material which is to be fed to the separating device and is entrained with the treatment gas.

5. Process according to any one of Claims 1 to - 4,characterized in that «coarse-grained material is introduced into the separating device.

6. Process according to any one of Claims 1 to S,characterized in that coarse-grained material is added to the finely particulate material which is removed from the separating device.

1. Process according to any one of Claims 1 to 6,characterized in that coarse-grained material is added pneumatically with the aid of a carrier gas.

8. Process according to any one of Claims 1 to 7,characterized in that coarse-grained material is added using the force of gravity.

9. Process for reducing fine ore according to any one of Claims 1 to 8, characterized in that the coarse-grained material is formed by ore and/or additives.

10. Process according to Claim 9, characterized in that the additives are lime, dolomite or MgO.

11. Process according to any one of Claims 1 to 10, characterized in that the treatment gas and the fine- grained material are separated from one another in the separating device with a separation chamber by means of centrifugal-force deposition, the treatment gas and Amended sheet 8/12/2004 the fine-grained material flowing into the separation chamber via an opening, and the at least partially cleaned treatment gas being removed again from the separation chamber by flowing out of the separation chamber, via a line, and a coarse-grained material additionally being fed to the separation chamber, if appropriate via a further opening, and in that the - material which has been separated off is discharged via a dedicated line.

12. Process according to Claim 11, wherein the line via which the at least partially cleaned treatment gas is removed from the separation chamber is a submerged pipe.

13. Process according to any one of Claims 1 to 12, characterized in that coarse bulk material is fed into the separation chamber in a predetermined grain size, composition and/or amount at which the occurrence of caking in the separation chamber is reduced and/or caking which has already occurred is at least partially removed.

14, Process according to any one of Claims 1 to 13, characterized in that the coarse material is supplied via the line for discharging the at least partially cleaned treatment gas.

15. Process according to any one of Claims 1 to 14, characterized in that the coarse material has a mean grain size which at least partially prevents undesired discharge from the separation chamber, via the line for removing the at least partially cleaned treatment gas. Amended sheet 8/12/2004

16. Apparatus for carrying out the process according to any one of Claims 1 to 15, having at least one fluidized-bed reactor with a lower part, which accommodates the fluidization zone, and with an upper part, which is connected to a deposition device, the deposition device being formed by a separating device, in which material in fine particle form can be separated from the treatment gas, a means for feeding treatment gas and material in fine particle form into the separating device, a treatment-gas discharge line, which leads out of the separating device, and a solid discharge line, which leads out of the separating device, characterized in that the deposition device is provided with a means for feeding coarse-grained material into the deposition device, the solids discharge line opening out into the fluidization zone and that the means for supplying coarse-grained material 1s connected to the means for supplying treatment gas in such a manner that coarse-grained material can be introduced into the stream of finely particulate material which is entrained with the treatment gas.

17. Apparatus according to Claim 16, characterized in that the separating device is a cyclone.

18. Apparatus according to either of claims 16 or 17, characterized in that the means for supplying coarse- grained material is designed as a lance which opens out into the interior of the separating device in such a manner that coarse-grained material can be introduced into the interior of the separating device.

19. Apparatus according to any one of Claims 16 to 18, characterized in that at least one additional Amended sheet 8/12/2004 inlet opening, through which coarse-grained material can be introduced into the separating device by the means for supplying coarse-grained material, is provided on the separating device.

20. Apparatus according to Claim 19, characterized in that the additional inlet opening 1s designed as a filler connection piece.

21. Apparatus according to either one of Claims 19 or 20, characterized in that an additional inlet opening is arranged in such a manner that coarse-grained material can be introduced into the cyclone substantially tangentially by the means for supplying coarse-grained material.

22. Apparatus according to any one of Claims 19 to 21, characterized in that an additional inlet opening is arranged in such a manner that coarse-grained material can be introduced into the separating device from above by the means for supplying coarse-grained material.

23. Apparatus according to any one of Claims 16 to 22, characterized in that the means for supplying coarse-grained material 1s connected to the solid discharge line, with the result that coarse-grained material can be introduced into the stream of finely particulate material which has been separated out in the separating device.

24. Apparatus according to any one of Claims 16 to 23, characterized in that the deposition device is arranged outside the fluidized-bed reactor, the solids discharge line opening out into the or a further fluidized-bed reactor. Amended sheet 8/12/2004

25. Apparatus according to any one of Claims 16 to - 24, characterized in that the deposition device is arranged inside the fluidized-bed reactor, the treatment-gas discharge line being guided to outside the fluidized-bed reactor and the solid discharge line opening out into the fluidization zone.

26. Apparatus according to any one of Claims 16 to 25, characterized in that the means for supplying coarse- grained material 1s designed as a pneumatic feed device.

27. Apparatus according to any one of Claims 16 to 26, characterized in that * a filter and/or a grate, by means of which the : coarse material can be separated from the deposited fine-grained material, and * a device for extracting the coarse material, if appropriate from the filter and/or the grate, are arranged beneath the separation chamber.

28. Apparatus according to any one of Claims 16 to 27, characterized in that the filling connection piece is provided as part of a device for the metered supply of the coarse material, the device also having a controllable lock or a controllable star feeder or another component for the metered supply of the coarse material.

29. Apparatus according to Claim 28, characterized in that the device for controlled supply has a vessel which can be coupled to the filler connection piece.

30. Process for reducing the amount of gas which flows out of a separation chamber in which solids are separated out of a gas by means of centrifugal-force Amended sheet 8/12/2004 deposition, and the at least partially cleaned gas is removed via at least one removal line, and the separation chamber, as a result of at least partial blockage by the deposited solids, has a deposition capacity which is lowered, compared to standard operation, characterized in that, to at least partially seal the line for removing the gas, which in normal operation has : been at least partially cleaned in the separation - chamber, a coarse bulk material is introduced in sufficient amounts into the separating chamber and/or the line for removing the gas.

31. Process according to Claim 30, characterized in that the gas is at least partially prevented from leaving the separation chamber via the line for removing the cleaned gas by a bed of bulk material which is caused by the introduction of the coarse bulk material.

32. Process according to either of Claims 30 or 31, characterized in that the coarse bulk material has a mean grain diameter which at least partially prevents undesired discharge via the gas flow out of the separation chamber via the line for removing the cleaned gas. Amended sheet 8/12/2004