Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B1/00—Preliminary treatment of ores or scrap
  • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
  • C22B1/16—Sintering; Agglomerating
  • C22B1/20—Sintering; Agglomerating in sintering machines with movable grates
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
  • F27B21/00—Open or uncovered sintering apparatus; Other heat-treatment apparatus of like construction
  • F27B21/06—Endless-strand sintering machines
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B1/00—Preliminary treatment of ores or scrap
  • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
  • C22B1/16—Sintering; Agglomerating
  • C22B1/20—Sintering; Agglomerating in sintering machines with movable grates
  • C22B1/205—Sintering; Agglomerating in sintering machines with movable grates regulation of the sintering process

Definitions

• the invention relates to a method for sintering iron oxide-containing substances on a sintering belt having a sintering belt, suction boxes and a sintering machine according to the preamble of claim 1.
• the sintering of iron oxide-containing substances is carried out on sintering machines.
• the sinter mixture consisting of the iron ore, return material, solid fuel and aggregates, is charged onto the sintering belt and the fuel is ignited on the surface of the material bed under the ignition furnace.
• Fresh air is then sucked through the sinter bed and the sinter front moves from top to bottom through the sinter bed.
• the exhaust gas is sucked into the gas collection system from the suction boxes under the upper run of the sintered bed and, after cleaning, discharged into the atmosphere.
• the sintering process requires heat transfer between the hot combustion gas and the cold solid.
• the amount of solids and the amount of air are heat equivalent.
• the exhaust gas contains evaporated water from the sintering mixture, CO 2 from the combustion of the fuel and from calcination processes, sulfur oxides from the combustion of sulfur - mainly from the added fuel - CO from incomplete combustion, false air and air that flows between the side walls of the grate wagon Feed enters the exhaust gas unused.
• the exhaust gas also contains dioxins and furans, in particular the exhaust gas drawn off from the rear part of the sintering belt.
• the exhaust gas also carries dust with it, which must be removed.
• the exhaust gas is preferably partially recorded and returned to the sintering belt once as recycle gas and once again discharged as residual gas.
• a fresh air supply line opens into the circuit line.
• DE 19623981 discloses a method for removing harmful ingredients from exhaust gases from sintering plants.
• powdered sorbents in the form of brown coal coke are added to the exhaust gas stream and the exhaust gas stream laden with sorbents is subsequently passed through an electrostatic filter.
• the loaded sorbents are returned to the sintering process after they have been filtered out.
• the method can be improved if the exhaust gas flow is passed through a pre-separator before it passes the electrostatic filter.
• the object of the invention is to further optimize the sintering process in such a way that, with a still small amount of exhaust gas and good sintering quality, in particular the dioxins and furans still present in the residual gas and the amount of dust are reliably below the limit values specified by the licensing authority.
• the object is achieved on the basis of the preamble in conjunction with the characterizing features of patent claim 1.
• Advantageous further developments are the subject of subterranean claims.
• the total amount of exhaust gas is divided into
• Circulation gas and residual gas by varying the process area, the location of the interface between the extraction for the circulation gas and the extraction for the residual gas being selected so that a maximum amount of exhaust gas is conducted in the circuit without impairing the sintering quality and performance, and the residual gas is a partial quantity with lower and the cycle gas is a subset with higher pollutant concentration. Furthermore, the amount of heat of the withdrawn cycle gas is used to heat the residual gas, with the heating up to a temperature to avoid falling below the dew point, but which is lower than the mixing temperature ensured when the total amount of exhaust gas is discharged.
• the proposed division of the process surface of the sintering belt with respect to the exhaust gas into a subsection, the exhaust gas amount of which is conducted as recycle gas and into a section, the exhaust gas of which is discharged as residual gas, has the purpose of dividing the exhaust gas flow into a subset that is less polluted with regard to the pollutant concentration and into a subset to divide with higher concentrations.
• the less polluted portion can be discharged as residual exhaust gas after separating the dust and the adsorbents introduced - including the dioxins and furans adsorbed on it - and after heating up to avoid the acid dew point via the chimney.
• the portion that is more heavily contaminated with respect to the dioxins and furans is circulated, taking advantage of the effect that a large part of the dioxins and furans are broken down when they are returned to the hot sintering mixture and are thus rendered harmless.
• the residual gas is withdrawn from the area of the sintering belt, which lies in the feed area and the area adjacent to it. This area is temperature-related low in comparison to the area of the cycle gas despite the heating to avoid falling below the H 2 SO 4 dew point.
• the adsorbents injected into the residual gas are particularly effective because of the low temperature of the residual gas, so that the remaining proportion of the pollutants in the residual gas to be discharged corresponds to the official requirements.
• An H 2 SO 4 dew point is not reached by heating the residual gas.
• the thermal energy of the cycle gas is used energetically.
• the proposed variation in the division of the process area is a very simple but effective means of being able to optimize the process.
• the ratio of oxygen supply to oxygen consumption approaches the ideal state 1 and thus the amount of exhaust gas is minimized.
• the performance of the system can be influenced if the sinter quality remains the same.
• the amount of exhaust gas circulated has the further effect that the required oxygen supply is lower compared to a normal process. In the borderline case, this allows with that brought in by the sucked-in false air
• the dust removal required in the area of cold screening is used as an oxygen carrier for the sintering process.
• the sinter mixture is used as a filter for the dust-laden suction air, so that no separate filter is required.
• Figure 1 is a schematic flow diagram of a sintering plant according to the invention.
• Figure 2 is a diagram of the method according to the prior art.
• Figure 3 is a diagram of the method according to the invention.
• Figure 4 is a schematic representation of the arrangement of the suction boxes and the flue gas manifolds.
• FIG. 1 shows in the form of a schematic flow diagram a sintering plant operating according to the invention.
• the core of the system is a sintering belt 1, in which case the sintering mix is placed on the right and the finished sinter is discarded on the left.
• This direction of transport is indicated by an arrow 2.
• Suction boxes and associated exhaust pipes 3, 4 are arranged to the right and left of the sintering belt 1, the exhaust gas drawn off in the beginning area of the sintering belt 1 being discharged as residual gas and the exhaust gas drawn off in the end area of the sintering belt 1 being circulated.
• the exhaust gas circulated is fed via a line 5 to a heat exchanger 6 and then via a further line 7, a filter 8 arranged therein, which has the function of separating the dust from the exhaust gas.
• the returned gas is fed via a line 9 to the sintering belt 1 by means of a suction blower 22 and distributed evenly over the sintering belt 1.
• the arrows shown are intended to clarify the task of the recirculated exhaust gas on the sintering belt 1.
• the residual gas to be discharged is over a line 10 is supplied to the already mentioned heat exchanger 6, the heat of the cycle gas being used for heating the residual gas. This is to avoid falling below the dew point for sulfuric acid.
• the residual gas is fed via a line 11 to an entrained flow reactor 12.
• lignite-coke breeze is blown in as known as adsorbent so that the harmful substances in the residual gas, such as dioxins and furans, can attach to it.
• the residual gas is fed via a line 13 to a filter 14 in which the dust and the adsorbents previously blown in are separated out. Thereafter, the residual gas cleaned in this way is fed to a chimney 16 by means of a suction blower 23 via a line 15 and distributed into the environment.
• the optional separate fresh air supply 21 shown in FIG. 1 is only required if the oxygen supply introduced by the sucked-in false air is too low.
• the finished sinter is discarded at the end of the sintering belt 1 and cooled in rotary coolers 17, 18.
• the air extracted in the rotary coolers 17, 18 is fed via a line 19 to a filter 20 in order to separate the entrained dust.
• the extracted dust from the sintering plant itself, as well as accumulating gout dust and casting hall dust from the blast furnace are agglomerated with water with the addition of quicklime to conical particles (mini pellets).
• This agglomeration takes place in a mechanical eddy current mixer 24, also called "Eirich mixer”.
• the moist agglomerates are continuously fed to the sinter mixture in the specified area.
• FIGS. 2 and 3 are compared with one another in FIGS.
• the cross line drawn thick in FIG. 3 symbolizes the separation according to the invention of the sintered strip 1 into an area of recycle gas and an area of residual gas, the double arrow indicating the possibility of displacement of the separation point.
• the displacement of the separation point according to the invention enables the process to be largely optimized.
• the optimum can be set easily by moving the separation point.
• FIG. 4 shows a schematic representation of a partial area of the arrangement of the suction boxes 25 and the flue gas collecting lines 5, 10.
• the suction boxes 25.1 located in the initial region of the sintering belt have a fixed separation 26 with respect to the discharge line for recycle gas 5. This is followed in this embodiment by a total of four suction boxes 25.2, which have a variable separation 27. Variable separation 27 means that these suction boxes 25.2 optionally on the discharge line circuit gas 5 or on the discharge line residual gas 10 can be switched. The effect that can be achieved with this was explained in detail at the beginning.
• the remaining suction boxes 25.3 up to the discharge area 28 are permanently connected to the circulation gas 5 discharge line.
• the fixed separation 29 arranged in the discharge line residual gas 10 can be removed in order to be able to discharge all of the resulting exhaust gas.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Geology (AREA)
• Geochemistry & Mineralogy (AREA)
• Manufacturing & Machinery (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• General Engineering & Computer Science (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
• Treating Waste Gases (AREA)

Applications Claiming Priority (3)

Publications (2)

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Family Applications (1)

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Cited By (1)

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• 2002
  • 2002-05-29 DE DE10224448A patent/DE10224448B4/de not_active Expired - Fee Related
• 2003
  • 2003-05-27 AU AU2003273380A patent/AU2003273380A1/en not_active Abandoned
  • 2003-05-27 EP EP03740059A patent/EP1507877B1/fr not_active Expired - Lifetime
  • 2003-05-27 KR KR10-2004-7019339A patent/KR20050004890A/ko not_active Application Discontinuation
  • 2003-05-27 DE DE50307021T patent/DE50307021D1/de not_active Expired - Fee Related
  • 2003-05-27 JP JP2004510487A patent/JP2005530923A/ja active Pending
  • 2003-05-27 AT AT03740059T patent/ATE359379T1/de not_active IP Right Cessation
  • 2003-05-27 WO PCT/DE2003/001813 patent/WO2003102252A1/fr active IP Right Grant

Non-Patent Citations (1)

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