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A process and apparatus for reducing material in particle form in a fluidization zone and at elevated temperature, in particular for reducing fine ore, the particle material being held in the fluidization zone by a treatment gas which flows upward from below. Material in fine particle form is disch

A process and apparatus for reducing material in particle form in a fluidization zone and at elevated temperature, in particular for reducing fine ore, the particle material being held in the fluidization zone by a treatment gas which flows upward from below. Material in fine particle form is discharged from the fluidization zone with the treatment gas and is separated out of the treatment gas in a deposition zone. In the deposition zone, the stream of treatment gas and discharged material in fine particle form are fed into a separating device which removes the fine particle material from the treatment gas, the treatment gas is extracted from the separating device as off-gas, and the separated fine particle material is removed from the separating device. Coarse-grained material is then introduced into the deposition zone. This reduces the levels of caking and deposits of the fine particle material. A device for carrying out the process includes elements defining the zones.

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The invention claimed is: 1. A process for reducing material in particle form in a fluidization zone at elevated temperature, the method comprising: holding the material in particle form in the fluidization zone by flowing a treatment gas upward from below the fluidization zone into the fluidizatio

The invention claimed is: 1. A process for reducing material in particle form in a fluidization zone at elevated temperature, the method comprising: holding the material in particle form in the fluidization zone by flowing a treatment gas upward from below the fluidization zone into the fluidization zone; discharging a stream of treatment gas from the fluidization zone with material in fine particle form entrained therein; feeding the stream of treatment gas and entrained material in fine particle form to a separating unit; separating the fine particle material from the treatment gas in the separating unit; extracting the separated treatment gas from the separating unit as off-gas and delivering the separated fine particle material to a solids discharge line; and introducing a coarse-grained material at one or more locations in the flow path of the treatment gas and/or fine particle material from the fluidization zone such that the coarse-grained material and the discharged fine particle material travel together in the solids discharge line. 2. The process as claimed in claim 1, further comprising controlling the temperature of the coarse-grained material to be at least 200째 C. below the temperature of the treatment gas and of the temperature of the fine particulate material. 3. The process as claimed in claim 2, further comprising controlling the temperature of the coarse-grained material to be substantially at ambient temperature. 4. The process as claimed in claim 2, wherein the coarse-grained material is introduced into the stream of the fine particle material upstream of the separation unit so that the stream of the coarse-grained material is entrained with the treatment gas. 5. The process as claimed in claim 1, further comprising introducing the coarse-grained material into the separation unit. 6. The process as claimed in claim 1, further comprising adding coarse-grained material to the fine particle material in the solids discharge line. 7. The process as claimed in claim 1, further comprising introducing the coarse-grained material pneumatically with the aid of a carrier gas. 8. The process as claimed in claim 1, further comprising introducing the coarse-grained material by gravity. 9. The process as claimed in claim 1, wherein the coarse-grained material comprises at least one of ore to be reduced and additives for the ore. 10. Apparatus for reduction treatment of material in particle form, the apparatus comprising: a fluidized-bed reactor having an upper part and having a lower part, and a fluidization zone in the lower part; a deposition device connected to the fluidization zone the deposition device comprising a separating device in which material in fine particle form can be separated from a treatment gas; a feeder 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 particle discharge line which leads out of the separating device; a feed device for feeding coarse-grained material into the deposition device; and an additional inlet opening into the separating device for introducing coarse-grained material fed by the feed device, the additional opening being arranged such that coarse-grained material can be introduced into the separating device from above by the feed device. 11. The apparatus as claimed in claim 10, wherein the feed device for coarse-grained material comprises a lance which opens out into the interior of the separating device for introducing coarse-grained material into the interior of the separating device. 12. The apparatus as claimed in claim 10, wherein the feed device for coarse-grained material is connected to the feeder for supplying treatment gas such that coarse-grained material can be introduced into the stream of fine particle material which is entrained with the treatment gas. 13. The apparatus as claimed in claim 10, wherein the separating device comprises a cyclone, and the additional inlet opening is arranged such that coarse-grained material can be introduced into the cyclone substantially tangentially by the feed device. 14. The apparatus as claimed in claim 10, wherein the feed device for supplying coarse-grained material is connected to the solids particle discharge line for introducing coarse-grained material into a stream of fine particle material which has been separated out in the separating device. 15. The apparatus as claimed in claim 10, wherein the deposition device is arranged outside the fluidized-bed reactor, and comprising a further fluidized-bed reactor into which the solids particle discharge line opens out. 16. The apparatus as claimed in claim 10, wherein 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 solids particle discharge line opening into the fluidization zone. 17. The apparatus as claimed in claim 10, wherein the feed device for supplying coarse-grained material comprises a pneumatic feed device. 18. A process for reducing the amount of gas which flows out of a separation chamber, in which solids are separated out of a gas by centrifugal-force deposition, and the at least partially cleaned gas is removed via at least one gas removal line, wherein the separation chamber has a deposition capacity which is lowered, as compared to standard operation, as a result of at least partial blockage by the deposited solids, the process comprising: at least partially sealing the gas removal lines which in normal operation has been at least partially cleaned in the separation chamber by introducing a coarse bulk material in sufficient amount into at least one of the separation chamber and the removal line for removing the gas. 19. The process as claimed in claim 18, wherein the gas is at least partially prevented from leaving the separation chamber via the gas removal line by a bed of bulk material which is caused by the introduction of the coarse bulk material. 20. The process as claimed in claim 19, wherein the coarse bulk material has a mean grain diameter selected to at least partially prevent an undesired discharge via the gas flow out of the separation chamber via the removal line. 21. An apparatus for cleaning a dust-laden gas, comprising: a separation chamber in which a solids component can be at least partially separated from a gas phase of the gas using the principle of centrifugal-force deposition; an inlet for the gas to be fed to the separation chamber; a line for removal of gas from the separation chamber for removing the at least partially cleaned gas; a filling connection piece for introducing coarse bulk material via at least one of the line for removal of the at least partially cleaned gas and/or at the separation chamber; a filter mechanism at which the coarse bulk material can be separated from the deposited dusts; and an extracting device for extracting the coarse bulk material from the filter, the filter mechanism and the extracting device being arranged beneath the separation chamber. 22. The apparatus as claimed in claim 21, further comprising a device for metered supply of the coarse bulk material, and the filling connection piece being part of the metered supply device; a controllable lock, or a controllable star feeder or another component for the metered supply of the bulk material at the metered supply device. 23. The apparatus as claimed in claim 22, wherein the metered supply device includes a vessel which can be coupled to the filling connection piece. 24. The process as claimed in claim 1, wherein the coarse-grained material is introduced into the stream of the fine particle material which is to be fed to the separation step so that the stream of the fine particle material is entrained with the treatment gas. 25. The process according to claim 1, further comprising introducing the coarse-grained material into the separation step. 26. The apparatus as claimed in claim 10, wherein the separating device comprises a cyclone. 27. The apparatus as claimed in claim 10, further comprising an additional inlet opening into the separating device for introducing coarse-grained material fed by the feed device. 28. The apparatus as claimed in claim 27, wherein the separating device comprises a cyclone, and the additional inlet opening is arranged such that coarse-grained material can be introduced into the cyclone substantially tangentially by the feed device. 29. The apparatus as claimed in claim 27, wherein the additional inlet opening is arranged such that coarse-grained material can be introduced into the separating device from above by the feed device for supplying coarse-grained material. 30. The process as claimed in claim 18, wherein the coarse bulk material has a mean grain diameter selected to at least partially prevent an undesired discharge via the gas flow out of the separation chamber via the removal line. 31. Apparatus for reduction treatment of material in particle form, the apparatus comprising: a fluidized-bed reactor having an upper part and a lower part, with a fluidization zone in the lower part; a deposition device connected to the fluidization zone for receiving treatment gas exiting from the fluidized-bed reactor having material in fine particle form entrained therein, the deposition device comprising a separating unit in which the fine particle material can be separated from the treatment gas; a feeder for feeding treatment gas and material in fine particle form into the separating unit; a treatment gas discharge line, which leads out of the separating unit, and a solids particle discharge line which leads out of the separating unit; a feed device for feeding coarse-grained material into the flow path of the treatment gas and/or fine particle material from the fluidization zone at one or more locations such that the coarse-grained material and the discharged fine particle material travel together in the solids particle discharge line. 32. The apparatus as claimed in claim 31, wherein the feed device for coarse-grained material comprises a lance which opens out into the interior of the separating unit for introducing coarse-grained material into the interior of the separating unit. 33. The apparatus as claimed in claim 32, wherein the feed device for coarse-grained material is connected to deliver the coarse-grained material into the feeder upstream of the separating unit. 34. The apparatus as claimed in claim 31, wherein the separating device comprises a cyclone, and an additional inlet opening is arranged such that coarse-grained material can be introduced into the cyclone substantially tangentially. 35. The apparatus as claimed in claim 31, wherein the feed device for the coarse-grained material is connected to the solids particle discharge line for introducing coarse-grained material into a stream of fine particle material which has been separated out in the separating unit. 36. The apparatus as claimed in claim 31, wherein the deposition device is arranged outside the fluidized-bed reactor, and comprises a further fluidized-bed reactor into which the solids particle discharge line opens out. 37. The apparatus as claimed in claim 31, wherein 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 solids particle discharge line opening into the fluidization zone. 38. The apparatus as claimed in claim 31, wherein the feed device for supplying coarse-grained material comprises a pneumatic feed device.