CA2184843A1 - Method and arrangement for heat-treating a material - Google Patents
Method and arrangement for heat-treating a materialInfo
- Publication number
- CA2184843A1 CA2184843A1 CA 2184843 CA2184843A CA2184843A1 CA 2184843 A1 CA2184843 A1 CA 2184843A1 CA 2184843 CA2184843 CA 2184843 CA 2184843 A CA2184843 A CA 2184843A CA 2184843 A1 CA2184843 A1 CA 2184843A1
- Authority
- CA
- Canada
- Prior art keywords
- treatment
- treatment bed
- bed
- treated
- exhaust gas
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- 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
Abstract
The installation proposed includes a conveyor belt (7) on which a bulk sinter mixture is deposited by a device (9). The conveyor belt carries the sinter mixture through a sintering plant (1) at the entry to which is disposed an ignition oven (3). The oven ignites the upper surface of the sinter bed. An extractor (11) located below the sinter bed sucks the burning zone down into the sinter bed. Located below the sinter bed at the output end of the sintering plant (1) is a second ignition oven (4) which ignites the lower surface of the sinter bed. A second extractor (6) sucks the second burning zone upwards. The pollutant content of the exhaust gases is significantly reduced since, in the input zone, the uninserted material acts as a filter while, in the output zone, combustion of the pollutants produced takes place in the upper-surface combustion zone. An additional adsorption agent ensures that the pollutants emerge mainly in the output zone of the sintering plant.
Description
METHOD AND ARRANGEMENT FOR HEAT-TREATING A
MATERiAL
The invention relates to a method for heat-treating a flowable material, especially for sintering metallic materials according to the preamble of claim 1. Furthermore, the invention relates to an arrangement according to the preamble of claim 13.
Method and ci, r~l-ge~ "l of the dru~ l ,liol1ed kind will be explained first with the aid of Fig. A in which as a treatment apparatus a conventional sintering device with first auxiliary devices is S~ ldLiC~ 'y represented.
The arrangement l~ ser,l~d in Fig. A is ~u",,~ ed si,u~dllli-:ly of a sintering device 1 with an ignition furnace 3 arranged at the upstream side thereof, a sintering bed ll~"~ o, li"~
device 5 which comprises an endless sintering band 7 guided through the sintering device, a sinter mixture feeding device 9, and an exhaust gas removal device 11 with which the pressure yradient extending from the top to the bottom through the sintering bed is produced for the sinterinr~ process.
The sinter mixture for the sintering process explained with the aid of Fig. A is comprised of ores, flux materials, fuels, especially coke fines, quick lime, and return material of the 2~ 848~
sintering process itself. A mixing and rolling drum 13 provides for an intensive mixin3 of the granular, respectively, flowable mixture co" ",~lle, Itb as well as for a uniform granule size and shape of the sinter material. The feeding device 9 is supplied from the mixing and rolling drum 13 and pours the sinter mixture in a su~ dl~ lly uniform layer thickness onto the grid of the sintering band 7. In this known device with the aid of an upstream feeding device 15 a finished sinter layer is applied as a grid coating onto the sinter band 7 and is arranged between the actual sintering bed, i.e., the sinter mixture layer and the grid in order to protect in the manner of a temperature barrier the grid from extreme temperature exposure and loads. The finished sinter layer remains unaffected by the subsequent sintering process in the sintering device 1 and does not interfere with sllhse~lPnt ,ulucess~ steps in a breaking device 17, a sinter cooling device 19, and in a cold sifting station 21 up to the point of obtaining the ready-to-use finished sinter at the outlet location 23.
The uul I t!Spu~ 9 conventional sintering process is carried out as follows. First, a suitable grid coating layer is uniformly applied with the feeding device 15 onto the sinter band 7. Onto the grid coating layer the sinter mixture is poured as uniformly as 2~ 848~
possible in a ~ d~ d layer thickness over the entire width of the bed. From the supply location of the sinter mixture below the feeding device 9, the sinter band 7 moves to the leff of the sintering device. The sinter bed is ignited by the ignition furnace 3 at the side facing the furnace upon entering the sintering device 1. Vvith the removal device 11 below the bed a pressure gradient is produced within the sinter bed over the entire sintering device 1 via which combustion air is introduced into the combustible sinter mixture and exhaust ~ases are removed at the second sinter bed side (underside). Affer i~nition of the carbon-~,ol lldil lil l9 fuel of the sinter mixture, a combustion zone is formed within the sinter bed which with the advance of the sinter bed within the sintering device from the right to the leff moves from the top of the sinter bed to the bottom, whereby the sinter material in this zone is sintered and baked together. The course and the formation of the combustion or sintering zone over the depth of the sintering bed is shown as a function of the length of the sintering band in the interior of the sintering device 1 in Fig. B. The depth of the bed in this example is 5ûO mm. As can be seen in Fig. B, the combustion, respectively, sinterin~ zone at the end of the sintering process, respectively shortly before exiting from the sintering ~' 21 ~4843 device 1, has reached the bottom of the sintering bed and softens also in this area the material to be sintered to such an extent that the individual material granules bake together (ayylu,l,el(A":).
This prfurnace sintering process has, as is well known, the disadvantage that the exhaust gases withdrawn from the sintering layer are loaded with a high percentage of pollutants which must be removed before the exhaust gases can be released into the surrounding ..~."os~,l,e,~. The purification of sinter exhaust gases has been carried out in practice with secondary exhaust gas purification devices. The investment cost of secondary exhaust gas purification devices which reduce the pollutant emission in a reliable manner are extremely ~tigh because the exhaust gas is highly loaded with pollutants over the entire length of the sintering bed and restrictively large gas volumes must be taken care of during the scrubbing operation. Therefore, exhaust gas purification has been limited to the use of dust filters (dust removal from the band in Fig. A) or has been ptlrullll~d by a somewhat more effective exhaust gas purification, for example, in scrubbers.
The especially critical cl,loruolydlli,, substances, heavy metals, etc. in contrast have not been removed because of the high costs involved .
It is therefore an object of the invention to remove the pollutants produced in a heat-treatment process of the ."t:",t~ io"ed kind substantially completely with comparatively low investment costs, preferably by reducing the volume of exhaust gas to be purified.
The solution to this object is based on the idea that the disclosed conventional sintering process inherently has already numerous properties and phases which favor exhaust gas purification but in the past could not be taken advantage of in a suitable manner. This is achieved inventively, i.e., with the inventive features of the method of patent claims 1, 2, 3, 4 and 6 and according to the inventive arrangement with the features of patent claims 13, 14, 15 and 16.
The invention no longer employs secondary exhaust gas purification measures for great gas volumes which require extremely high investment costs. Instead, it incorporates in all alternative solutions the exhaust gas purification suL,~lal llk311y into the primary sintering process. The invention is based on the idea that in the known manner of heat treatment a strongly absorbing fllter layer is positioned downstream of the combustion zone as long as the combustion zone has not yet penetrated to the 21 8~8~3 . ~
exhaust gas side opposite the ignition side. The purification effectof this "natural" a~ulluliù~l layer is used in the invention. Before the cleaning effect based on combustion of the carbon-containing (ad~ol,uliull-effective) fuel ~i~d,upea,~ and the combustion zone pe~ Les to the other side, in a first inventive solution the pressure gradient is reversed and a counter combustion is generated. In this manner adjacent to the second combustion zone which migrates to the other side another layer is arranged ~Jo...~ lll which initially can act as a filter layer. Before col"l.;,li"g the two combustion zones, the ulllulùulydlli~
substances which are released in the second combustion zone, for example, dioxins or furanes, are combusted under the influence of the high temperature of the first combustion zone, respectively, are adsorbed by remaining carbon particles and are subsequently also combusted.
According to another inventive solution the exhaust gases exiting from the treatment bed are collected and introduced into the i~qnition furnace. In this context it is possible to return all of the ,qases exitiny from the treatment device or only the gases containing a critical amount of pollutants from partial phases, especially of the end phase of the treatment process. Due to the influence of the high temperatures~within the ignition furnace the pollutants within the exhaust gas are destroyed. The exhaust gases are then guided through the treatment bed under the effect of the pressure gradient present within the treatment bed. Upon doing so, they are again exposed to high temperatures within the area of the combustion zone and are further purified in this manner. The "natural" purification layer positioned downstream of the combustion zone within the treatment bed adsorbs furthermore remaining pollutants still contained within the exhaust gas.
In an alternative treatment process the exhaust gases exiting from the treatment bed at the end phase of the process are collected and are guided together with the gases required for the heat treatment into the treatment bed at the initial phase andlor the central phase of the process. The exhaust gases can be areally distributed over the treatment bed and can be guided therethrough. The pollutants therefore must not be co~ ,..~d within the area of the ignition furnace but can be supplied together with combustion air in low cullcelllld~iulls~ The pollutants contained within the exhaust gas, for example, dioxins or furanes, are destroyed under tlle infiuence of the high temperature upon passing of the gas mixture through the combustion zone. In this 2 1 848~3 process alternative the cleaning effect of the natural a,l~or,uliul,layer arranged behind the combustion zone is also employed.
Only minimal technical retrofitting measures are required for realizing the method are required so that the resulting costs are CUI I l,Udl dli"ely low.
In a further alternative treatment process the pressure gradient and thus the combustion of the fuel layers within the bed from the beginning to the end of the treatment process is I l Idil lli~lil led. During the migration of the combustion zone from the top to the bottom the relatively cool, un,treated mixture layer positioned llle,~uelo.. acts as an adbo"uliull filter. Its filter effect is reinforced by the lowest (first) layer consisting of ad~ol,u~iull-suitable material, especially coke. This layer is protected against combustion by the second layer made of inert material which acts as a temperature barrier. This layer is an a~ùlluLiùll filter layer which is carried along within the primary process. Instead of lumpy or granular coal or coke other lumpy or granular material with 1ù,ll,ual~le ad~ul,u~iull or filtering properties can be used.
The last named process alternative makes obsolete a change of the conventional treatment device. The coke which functions as the adsul,uli~l, medium is pored as a first layer onto 2~ ~4~43 the grid supporting the layer sequence and ac~v""~a~ s the actual treatment process as a primary filter. This coke layer is not wasted. Most of the coke, on the one hand, can be separated at the end of the treatment process from the remaining layers and can optionally be returned and reused; on the other hand, the coke used as a filter layer during the heat treatment can be used in the blast furnace as a l~Jlc,Cts,~ of other coke materials.
In a further alternative method, with a directed displacement of the pollutant profile in the direction of the profile of the exhaust gas temperature and especially by overlapping the correspondin~q profile maxima, the pollutants are col,c~"ll,~lt,.l onto the section of the device in which the exhaust gas temperature is especially high. The purification of exhaust gases can thus be limited to a correspondingly short section of the treatment area in which the pollutant collcell~l.9i~ll and exhaust gas temperature are at a maximum. In this manner, purification devices of a small capacity are sufficient in order to operate the entire treatment device with very low pollutant emission.
The di:~Jldctelllelll of the pollutant cul,ce,,ll~;vll profile is achieved by enriching the treatment bed with pollutant-adsorbing media which retain the pollutants until the last section of the g ` ~ 218484~
treatment area (for example the sintering apparatus) is reached.
Oniy at the end of the treatment area when the capacity of the pollutant-adsorbing medium is depleted and the combustion zone reaches the lower layers in which the pollutants are retained at high collce~ ;lLiulls the cunce~ iull of pollutants within the exhaust gas rises greatly. This portion of the exhaust gases which is greatly pollutant-loaded can then be cleaned separately.
Instead of introducing additional pollutant-adsorbing media into the treatment bed it is possible to use media with improved ~:,oruli~n properties in ~ ~ ul1S in which the treatment process requires the use of pollutant-ad~u,L,e"l media within the treatment bed. A greater specific surface area of the individual adboruliol~ medium particles can for example lead to the desired ~i_,,lacul"e,l~ of the pollutant uul~c~ Livll profile.
Advantageously the pollutant-ads~ "L media are mixed well with the material to be treated and are then poured onto the grid before they are introduced into the treatment area. It is thus possible SULJ~ldl lli..'l~ without any technical expenditure to uniformly distribute the pollutant-adsorbing media within the treatment bed.
In a further development of the invention it is su~gested 21~4843 that the pollutant-adsorbent media are provided within the lower area of the treatment bed in a higher cullc~rllli~liu" than in the upper area of the treatment bed. Varying collc~"l,~ n ratios between the pollutant-adsorbent media and the material to be treated can be produced during mixing. In order to produce an especially steep conct~r~ " I profile of the pollutants, it is favorable to gradually increase the ~oncel ,11 iiliull of the pollutant-adsorbing medium from the top to the bottom within the treatment bed. Instead, it is also possible to provide a plurality of two layers with different c~llce"lliilioll ratios.
A preferred ~IllI.odi,,,~,,l is ull~ ttli~t:d in that the collected exhaust gases are catalytically purified by employing their own high temperature. An effective catalytic purification is possible only at temperatures above 300 C. By overlapping the pollutant ~unce~ lioll maximum with the temperature maximum the required high temperature for the catalytic cleaning is achieved in most heat treatment processes. It is not necessary to provide additional heat energy; instead, the heat energy released by the process of heat treatment is collected and is suffficient as a heat source. It is furthermore advanta~eous, that the heat is not returned into the surroundings as waste heat. By catalytic ~78484~
puriflcation different pollutants can be removed from the exhaust gas. For example, ul llul Uolydl ~ic substances such as dioxins and furanes can be reduced with suitable reduction catalysts. Also, nitrogen oxides can be reduced without problems in this temperature range. A catalytic oxidation is, for example, also possible for pollutants such as SO2; SO2 is oxidized to SO3.
As an advantageous embodiment of the invention it is suggested that the pollutant-adsorbent media and their ~ul Ice, ,11 d~iUI 1~ within the treatment bed are selected such that the cul Ice, ,1, dliul I profile of the pollutants resulting within the treatment process and especially their maximum are overlapped within the end section of the treatment zone. The more CullC~Illldliol, profiles of different pollutants are overlapped and the steeper the .ullCell~l~Liull peaks are, the lower the partial volume of the exhaust gas to be purified will be and the more effective the inventive method will operate.
In a further development the exhaust gases exiting from the treatment bed in the last phase of the process are subjected to a particle sepdl d~iOll step. For this purpose, a conventional electric filter can be used. In order to achieve an especially high cleaning effect it is favorable to arrange downstream of the particle 218~843 separation a catalytic purification device.
Instead of the particle separation the exhaust gas can be cleaned with a.l~o, ~ media and water after catalytic purification. This is performed, for example, with the aid of a spray dryer with which carbon-containing adsor,uliull material in the form of dust and water are introduced into the exhaust gas stream. The introduced water reduces the exhaust gas tempsrature to such an extent that, for example, salts and chlorides will crystalize. In order to further improve the quality of the exhaust gas, instead of a spray dryer, or in addition to it, an active coke device can be used.
Advantageously, the exhaust gas is subjected to a particle sepdlaliul1 after cleaning with a-iso,,.Liùl~ medium and water.
A portion of the solid materials collected in the particle s2pdldliun step can be returned and used again as an adaur~uliull medium for cleaning. Since the ad~ull~ medium-containing solid materials have not cu~ t~ly exhausted their a~sul~ ull capacity for pollutants during their first run through the exhaust gas, it is possible by returning it to l~ad the a.l~o"u~ medium with pollutants up to its capacity limit and to thus reduce the operation costs. -13 --2~ ~fi~6F3 Advantageously the pollutant~adsorbent means is a carbon-cul"~i"i,ly flowable material for example coke fines and/or active coke. This material is i, ~ ellsive. In heat treatment processes above the ignition temperature of coke fines it will ignite and will release its combustion heat as additional heat into the treatment bed. No interfering foreign substances will remain within the treatment bed.
Preferably the inventive method is used during sintering of metallic materials.
Expedient devt~l.,,u" ,el,ts and embodiments of the invention are defined in the dependent claims.
In the following the invention will be explained in more detail with the aid of the drawing in which s~ ", ~y s~llLt~d ~Illbodi,ll~,,LO are shown. It is shown in the drawing:
Fig. 1 a schematic It~ Sellldli~l~ of a sintering ~y~ e~l for p~rullllillg a first sintering method according to the invention;
Fig. 2 a schematic l~p~se~ldli~ of a sintering d"d"g~",el,L for performing a second inventive method alternative;
Fig. 3 a schematic representation of a sintering . ~ 2~84843 d,l~l,gt""~"l for performing a third inventive method alternative;
Fig. 4 a schematic representation of a sintering for performing a fourth inventive treatment method;
Fig. 5 a schematic representation of a sintering arran~ement for p~,rul",i"g a fifth inventive method alternative;
Fig. 6 a schematic l~pl~se,,ld~iull of a sintering a"~ "el" for performing a sixth inventive method ~ ; "~t; ~ c;
Fig. 7a a schematic repl~s~,,ld~iùll of a sintering tll 1~1 ,~e" ,el ,~, Fig. 7b a diagram of exhaust gas temperature, plotted as a function of the length of the sintering band;
Fig. 7c a diagram of the exhaust gas collcel ,I, ;~liull of SO2 plotted as a function of the length of the sintering band;
Fig. 7d a diagram of the exhaust gas concentration of polychlorinated dibenzodioxins and .
-2~ ~4~4~
polychlorinated~dibenzofuranes, plotted as a function of the length of the sintering band;
Fig. 7e a diagram of the exhaust gas ,ullCt~ 1 d~iOl~ of nitrogen oxides, plotted as a function of the length of the sintering band.
The ~I ~ ,L~odi" ~"~ of the invention scl1e" Id~iC~lly I ~ 5~ d in Fig. 1 differs from the conventional sintering d"d"ge",~"~ of Fig. A on the one hand due to its second ignition furnace 4 which is arranged in the vicinity of the exit end of the sintering device 1 and which ignites the sintering bed from the underside and on the other hand by a device for g~ l d~il 15J a pressure gradient in the counter direction, i.e., from the underside of the bed to the upper side. This pressure gradient gel1~ld~i"~ device Colll~ 5 an exhaust removal hood 6 and a suction pump 10 co""~.,t~d to a return line 8.
The exhaust gas removed via the removal hood 6 can be freed of dust with a suitable filter 12. In a mixer 14 the exhaust gas is mixed with the combustion air required in the sintering device 1 at the forward, respectively, central area and is introduced together with the combustion air via the hood 16 from the top to the bottom through the sinter bed. Upon pel1~lldLillg the 2li ~84~
combustion zone, respectively, the high temperature of the sinterbed through which the combustion zone migrates, the olool!Jdlli~ substances are destroyed sufficiently and reliably.
Behind the combustion zone the exhaust gases newly formed during sinterin3, respectively, the returned exhaust gases pass through the sinter mixture in which the fuel cullL~illi,lg a great amount of carbon, in general the form of coke fines, is finely distributed. This fuel acts as an adsorption medium in which a substantial portion of the pollutants, similar to the conventional secondary purification of the exhaust gases in active coke reactors, is adsorbed In the schematic drawing according to Fig. 2 only the feeding section of the sinter bed transport device 5 is s~ e",d~ 'ly ,~ se"'~i. Othen~ise, the sintering arld"g~",e,ll corresponds to the one of Fig. A. As can be seen, the sinter band 7 has arranged thereat in sequence three feeding devices. With an additional first feeding device 18 a thin a i~ol,ulioll medium layer 20 is applied to the grid. Do~ d"~ of the device 18 the feeding device 15, as already described in connection with Fig. A, for feeding the finished sinter layer 22 onto the a~ liol I medium layer 20 is arranged, and du~ a~ thereof the feeding device 21 ~4843 9 for feeding the sinter mixture 24 which forms the actual sinteringbed is arranged. During the sintering process the f nished sinter layer 22, which may be aiso comprised of another material with sulJ~Idl llidlly inert properties, provides a temperature barrier which prevents a migration of the combustion zone into the filter layer 20 of adsorptive capacity.
Fig. 3 shows a sintering all dl~yc" ,ent which is principally of a similar design as the one of Fig. 1. However, in the rearward area the sintering a, Idl1g~",e"l 1 lacks the second ignition furnace 4. Similar to the dl I dl~gd" ,e~ I~ of Fig. 1, an exhaust gas collecting device 6' is provided which however is arranged at the underside of the sintering bed for producing a conventional pressure gradient. The collected exhaust gas is returned via the return line 8 and the suction pump 10 to the mixing device 14, is mixed with combustion air, and introduced via the hood 16 in the forward and central area of the sintering device into the sintering bed. The purification effect of the sinter mixture on the other side of the combustion zone within the sintering bed is taken advantage of with this arrangement according to Fig. 3. The investment costs are lower especially because the second ignition device is obsolete and, furthermore, because the additional f Itering device 2 1 84~43 12 can be omitted.
The previously described primary exhaust gas cleaningmeasures can also be combined. For example, the exhaust gas return according to Fig. 3 can also be used when using the additional a.lbo"uliulI medium layer 20 of Fig 2. Fu~ ull"ul~, the exhaust gas can be returned to the ignition furnace or to the inlet area, respectively, central area of the sintering device external to the ignition furnace. Also, it can be introduced in cùll,bi, IdliUI1 into the ignition furnace area and a further area, for example, into the central area of the sintering device. Upon return of the exhaust gases only into the ignition furnace, the mixer 14 andlor the hood 16 can be omitted. In respect to the sinter bed conveying device no limitations are necessar,v in connection with the invention. The conventional sinter band device can, for example, be replaced by a so-called pusher type furnace in which the sinter bed is moved in sequentially arranged baskets and is pushed through the sintering device 1. The conveyor belt can be a continuously as well as a discontinuously driven belt.
In the device according to Fig. 4 the feeding device 9 serves for feeding not only the sinter mixture but also an additional adsorption medium. The sinter mixture is ,o"".rib~d in a manner ~ .
~78~843 known per se of ores, flux material, fuels, especially coke fines,quick lime, and return material of the sintering process itself. The adsorption medium is carbon-~o"ld;"i"g and granular, respectively, flowable.
By enriching the sinter bed with adsorption media, pollutants developing within the forward or central area of the centering device 1 are adsorbed to a greater extent. The pollutants are retained within the sintering bed so that the exhaust gases removed within the forward sections already comprises sufficient purity. The exhaust ~ases removed within the forward and central areas of the sintering devices with the exhaust gas removal device 11 (removal line 25), after particle separation with an eledric filter 25', can be introduced without further purification steps into the surrounding ~ us~ul~e~. The exhaust gases removed by the exhaust removal device 11 within the rearward area of the sintering device 1 are guided via a separate removal line 26. In this area of the sintering device the temperature of the exhaust gases is naturally very high. By enriching with pollutant-adsorbing media, the Cul l~ iol~ maximum of all critical pollutants, for example, possible ~,I llul uo, ~a"ic substances, nitrogen oxides, and sulfur dioxide are located within this rearward .
~ 2~8484}
area. Particles such as fly ash are separated with t~le electric f Ite!27 from the exhaust gas. Subsequently, the exhaust gasses are catalytically cleaned by adding reduction media. Within the catalytic cleaning reactor 28 the optionally present dioxins and furanes as well as nitrogen oxides are reduced by the reduction catalyst. An additional oxidation catalyst serves to oxidize SO2 to S03. The catalytic treatment is favored by high exhaust gas temperatures. The catalytically cleaned exhaust gas can then be released without further cleaning steps into the surrounding ~ti"ob~ e,~ (removal line 29).
The fifth embodiment represented in Fig. 5 of the inventive s~lld~lgelllellL differs from the one of Fig. 4 by a purification d"~ l"er~l dU...lSIl~dlll of the exhaust gas removal line 26. In this ~ :l l IL,o-li,, ,~I II the catalytic cleaning reactor 28 is directly loaded with pollutant-loaded exhaust gases. Subsequently, the exhaust ~ases are cleaned in an d.l~l,uIiul1 medium reactor 30, with addition of adsoll,Iiol, media and water, from sulfur oxides, dust, and organic substances. A fabric filter 31 arranged do.."~ d,l, of the ad~o"uIiul1 medium reactor 30 separates the adsorption medium and further solid material from the flue gas stream. The filtrate is partially returned via the return line 32 into the reactor in 2~84843 order to adsorb more pollutants therein and in order to completelyexhaust the adbor~ capacity of the particles.
Do.~.lsLI~,,, of the fabric filter 31 the exhaust gas has relatively high purity and can be returned together with the exhaust gas from the exhaust gas line 25 into the surrounding ~I",ob~ e,~. The exhaust gas in this ~",bodi,l,e"l fulfills the more stringent pollutant emissions limits and is especially enYi, ul ~ ,t ~I:y friendly.
The employed d,lbor,uli~," medium reactor 30 can be of a very small size because by concentrating the pollutant release within the rearward area of the sintering area only a small portion of the exhaust gas removed during the heat treatment process must be cleaned from the pollutants. The constructive expenditures are thus minimal. By returning the absorption medium into the reactor the operating cost are kept at a minimum.
In the ~",I,odi,l,e"l according to Fig. 6 the removal line 26 is flrst introduced into the electric filter 27 in which solid particles especially fly ash are separated. The actual cleaning is again carried out in the catalytic cleaning reactor 2~ at temperatures of dpf.l ~ 'y 300 to 400 C. Subsequently the hot exhaust gas ~ 2~ 8~8~3 is returned via a return line 33 into the ignition furnace. Here theexhaust gas is mixed with combustion air and returned into the sintering bed. The cleaning effect of the sinter mixture positioned doL~ l of the combustion zone within the sintering bed is taken advantage of in order to achieve an even higher purity of the exhaust gas.
The disclosed exhaust gas purification measures can also be combined. For example, the exhaust gas return according to Fig. 6 can also be used in addition to adso"uliull medium reactors.
Furthermore, the adsù",': 1 medium in the lower layer of the sintering bed can be introduced in higher ~ullC~ iDll than in the upper layers. The adsorption medium and the sinter mixture can also be applied onto the band in sequence. A separate adso~liull medium layer can be provided, separated by an isolation layer from the sinter mixture. Such an a.l~,,uliul~ medium layer can also be used in addition to an ~ lll of the material to be treated with adsorption material.
The ddsol,uliun medium itself can be a flux material and/or a material mixture used in conventional sintering processes, whereby its pollutant-adsorbent properties are improved in the spirit of the present invention. It is important that the ~84843 Co~ r,~, dliOIl profile of the pollutants is displaced according to the exhaust gas temperature profile. This will be explained in more detail with the aid of Fig. 7.
The sintering process begins below the ignition furnace 3.
The sinter band 7 moves in the direction of conveyance which is to the right in the shown drawing. With the conveying movement of the sinter bed the sinter zone moves simultaneously from the top to the bottom through the sinter bed.
Fig. 7a shows a diagram of the exhaust gas temperature plotted as a function of the sinter band length. The solid line ,~p,~:,e"~ the curve for a conventional sintering process and the dashed line lezl)~se~t~ the curve for the inventive method. This is true also for diagrams b-e. The curve of the exhaust gas temperature shows in the rearward area of the sintering device a strong maximum in the conventional as well as the inventive method. The course of the temperature is practically not affected by the invention.
Fig. 7b shows the diagram of the ~ollC~ dli~l~ of SO2 in the exhaust gas plotted as a function of the sinter band length.
In known sintering processes (solid line) the SO2 c~n~ ldlioll within the exhaust gas rises shortly behind the center of the ~ ~ 4 218~843 sintering device. The SO2 peak is very broad. The exhaust gasCo~ ldliùl\ of SO2 in the inventive method is constantly ri~d"LIy lower in the forward and central areas and rises sul~:~ld~ lly only at a later point with relatively steep flanks. The peak is displaced to the rear and su~sld,lli~'ly smaller.
In Fig. 7c the exhaust gas uull~el ~1~ dliOIls of polychlorinated dibenzodioxins and dibenzofuranes is plotted as a function of the sintering band length. In the conventional sintering process the ol)ce~ dliUIl of the ~ luruul ydlli~, substances rises already at the center of the sintering process. The peak is very broad in analogy to the peak of the SO2 exhaust gas ~;ullu~l 1ll dliun. In the inventive method the exhaust gas loading with ulllo~ uu, Udl Ik, substances in the forward and central areas is suLbldll" "y lower due to the a-l~or,u~ioll effect of the sinter bed, and the maximum is displaced by forming a sharp peak to the rear.
In Fig. 7e the exhaust gas col,cel,lldliulls of NOx is plotted as a function of the sinter band length. In the conventional sintering process the NOX COll~ll[ldliOIl is sul,~ld"li..lly constant over the entire length of the sintering band. Only at the end of the band the NOX drops s~b~ldl lli.~'ly linearly. This nec~ssi'.~'_d in the past a cleaning of the entire exhaust gas volume for removal of ` ~ 2~84843 NOx pollutants. The exhaust gas~concentration of NOx in theinventive method is negligibly low in the forward and central areas and rises to a peak only in the rearward section of the sinter band.
Thus, with the inventive method it is thus possible to concentrate the pollutants within the rearward area of the sinter band. The pollutant peaks are displaced to the rear and the col~ce~ l maxima coincide with the maximum of the exhaust gas temperature. In this manner, only a small portion of the resulting exhaust gas volume must be purified. The partial amount of exhaust gas to be cleaned is collected within the rearward area of the sintering device, i.e., at a location where the exhaust ~as temperature is sul,~ '!y within the optimum temperature range required for catalytic purification.
Various alternatives are possible with the invention.
Especially, the measures represented in Figures 1 to 6 can be combined in any desired fashion. The method is suitable for a plurality of heat-treating methods with similar advantages, especially also for roastin~ methods, for example, for the heat treatment of metal sulfides, especially lead, zinc and nickel in oxidizing ~I",o~phel~s.
MATERiAL
The invention relates to a method for heat-treating a flowable material, especially for sintering metallic materials according to the preamble of claim 1. Furthermore, the invention relates to an arrangement according to the preamble of claim 13.
Method and ci, r~l-ge~ "l of the dru~ l ,liol1ed kind will be explained first with the aid of Fig. A in which as a treatment apparatus a conventional sintering device with first auxiliary devices is S~ ldLiC~ 'y represented.
The arrangement l~ ser,l~d in Fig. A is ~u",,~ ed si,u~dllli-:ly of a sintering device 1 with an ignition furnace 3 arranged at the upstream side thereof, a sintering bed ll~"~ o, li"~
device 5 which comprises an endless sintering band 7 guided through the sintering device, a sinter mixture feeding device 9, and an exhaust gas removal device 11 with which the pressure yradient extending from the top to the bottom through the sintering bed is produced for the sinterinr~ process.
The sinter mixture for the sintering process explained with the aid of Fig. A is comprised of ores, flux materials, fuels, especially coke fines, quick lime, and return material of the 2~ 848~
sintering process itself. A mixing and rolling drum 13 provides for an intensive mixin3 of the granular, respectively, flowable mixture co" ",~lle, Itb as well as for a uniform granule size and shape of the sinter material. The feeding device 9 is supplied from the mixing and rolling drum 13 and pours the sinter mixture in a su~ dl~ lly uniform layer thickness onto the grid of the sintering band 7. In this known device with the aid of an upstream feeding device 15 a finished sinter layer is applied as a grid coating onto the sinter band 7 and is arranged between the actual sintering bed, i.e., the sinter mixture layer and the grid in order to protect in the manner of a temperature barrier the grid from extreme temperature exposure and loads. The finished sinter layer remains unaffected by the subsequent sintering process in the sintering device 1 and does not interfere with sllhse~lPnt ,ulucess~ steps in a breaking device 17, a sinter cooling device 19, and in a cold sifting station 21 up to the point of obtaining the ready-to-use finished sinter at the outlet location 23.
The uul I t!Spu~ 9 conventional sintering process is carried out as follows. First, a suitable grid coating layer is uniformly applied with the feeding device 15 onto the sinter band 7. Onto the grid coating layer the sinter mixture is poured as uniformly as 2~ 848~
possible in a ~ d~ d layer thickness over the entire width of the bed. From the supply location of the sinter mixture below the feeding device 9, the sinter band 7 moves to the leff of the sintering device. The sinter bed is ignited by the ignition furnace 3 at the side facing the furnace upon entering the sintering device 1. Vvith the removal device 11 below the bed a pressure gradient is produced within the sinter bed over the entire sintering device 1 via which combustion air is introduced into the combustible sinter mixture and exhaust ~ases are removed at the second sinter bed side (underside). Affer i~nition of the carbon-~,ol lldil lil l9 fuel of the sinter mixture, a combustion zone is formed within the sinter bed which with the advance of the sinter bed within the sintering device from the right to the leff moves from the top of the sinter bed to the bottom, whereby the sinter material in this zone is sintered and baked together. The course and the formation of the combustion or sintering zone over the depth of the sintering bed is shown as a function of the length of the sintering band in the interior of the sintering device 1 in Fig. B. The depth of the bed in this example is 5ûO mm. As can be seen in Fig. B, the combustion, respectively, sinterin~ zone at the end of the sintering process, respectively shortly before exiting from the sintering ~' 21 ~4843 device 1, has reached the bottom of the sintering bed and softens also in this area the material to be sintered to such an extent that the individual material granules bake together (ayylu,l,el(A":).
This prfurnace sintering process has, as is well known, the disadvantage that the exhaust gases withdrawn from the sintering layer are loaded with a high percentage of pollutants which must be removed before the exhaust gases can be released into the surrounding ..~."os~,l,e,~. The purification of sinter exhaust gases has been carried out in practice with secondary exhaust gas purification devices. The investment cost of secondary exhaust gas purification devices which reduce the pollutant emission in a reliable manner are extremely ~tigh because the exhaust gas is highly loaded with pollutants over the entire length of the sintering bed and restrictively large gas volumes must be taken care of during the scrubbing operation. Therefore, exhaust gas purification has been limited to the use of dust filters (dust removal from the band in Fig. A) or has been ptlrullll~d by a somewhat more effective exhaust gas purification, for example, in scrubbers.
The especially critical cl,loruolydlli,, substances, heavy metals, etc. in contrast have not been removed because of the high costs involved .
It is therefore an object of the invention to remove the pollutants produced in a heat-treatment process of the ."t:",t~ io"ed kind substantially completely with comparatively low investment costs, preferably by reducing the volume of exhaust gas to be purified.
The solution to this object is based on the idea that the disclosed conventional sintering process inherently has already numerous properties and phases which favor exhaust gas purification but in the past could not be taken advantage of in a suitable manner. This is achieved inventively, i.e., with the inventive features of the method of patent claims 1, 2, 3, 4 and 6 and according to the inventive arrangement with the features of patent claims 13, 14, 15 and 16.
The invention no longer employs secondary exhaust gas purification measures for great gas volumes which require extremely high investment costs. Instead, it incorporates in all alternative solutions the exhaust gas purification suL,~lal llk311y into the primary sintering process. The invention is based on the idea that in the known manner of heat treatment a strongly absorbing fllter layer is positioned downstream of the combustion zone as long as the combustion zone has not yet penetrated to the 21 8~8~3 . ~
exhaust gas side opposite the ignition side. The purification effectof this "natural" a~ulluliù~l layer is used in the invention. Before the cleaning effect based on combustion of the carbon-containing (ad~ol,uliull-effective) fuel ~i~d,upea,~ and the combustion zone pe~ Les to the other side, in a first inventive solution the pressure gradient is reversed and a counter combustion is generated. In this manner adjacent to the second combustion zone which migrates to the other side another layer is arranged ~Jo...~ lll which initially can act as a filter layer. Before col"l.;,li"g the two combustion zones, the ulllulùulydlli~
substances which are released in the second combustion zone, for example, dioxins or furanes, are combusted under the influence of the high temperature of the first combustion zone, respectively, are adsorbed by remaining carbon particles and are subsequently also combusted.
According to another inventive solution the exhaust gases exiting from the treatment bed are collected and introduced into the i~qnition furnace. In this context it is possible to return all of the ,qases exitiny from the treatment device or only the gases containing a critical amount of pollutants from partial phases, especially of the end phase of the treatment process. Due to the influence of the high temperatures~within the ignition furnace the pollutants within the exhaust gas are destroyed. The exhaust gases are then guided through the treatment bed under the effect of the pressure gradient present within the treatment bed. Upon doing so, they are again exposed to high temperatures within the area of the combustion zone and are further purified in this manner. The "natural" purification layer positioned downstream of the combustion zone within the treatment bed adsorbs furthermore remaining pollutants still contained within the exhaust gas.
In an alternative treatment process the exhaust gases exiting from the treatment bed at the end phase of the process are collected and are guided together with the gases required for the heat treatment into the treatment bed at the initial phase andlor the central phase of the process. The exhaust gases can be areally distributed over the treatment bed and can be guided therethrough. The pollutants therefore must not be co~ ,..~d within the area of the ignition furnace but can be supplied together with combustion air in low cullcelllld~iulls~ The pollutants contained within the exhaust gas, for example, dioxins or furanes, are destroyed under tlle infiuence of the high temperature upon passing of the gas mixture through the combustion zone. In this 2 1 848~3 process alternative the cleaning effect of the natural a,l~or,uliul,layer arranged behind the combustion zone is also employed.
Only minimal technical retrofitting measures are required for realizing the method are required so that the resulting costs are CUI I l,Udl dli"ely low.
In a further alternative treatment process the pressure gradient and thus the combustion of the fuel layers within the bed from the beginning to the end of the treatment process is I l Idil lli~lil led. During the migration of the combustion zone from the top to the bottom the relatively cool, un,treated mixture layer positioned llle,~uelo.. acts as an adbo"uliull filter. Its filter effect is reinforced by the lowest (first) layer consisting of ad~ol,u~iull-suitable material, especially coke. This layer is protected against combustion by the second layer made of inert material which acts as a temperature barrier. This layer is an a~ùlluLiùll filter layer which is carried along within the primary process. Instead of lumpy or granular coal or coke other lumpy or granular material with 1ù,ll,ual~le ad~ul,u~iull or filtering properties can be used.
The last named process alternative makes obsolete a change of the conventional treatment device. The coke which functions as the adsul,uli~l, medium is pored as a first layer onto 2~ ~4~43 the grid supporting the layer sequence and ac~v""~a~ s the actual treatment process as a primary filter. This coke layer is not wasted. Most of the coke, on the one hand, can be separated at the end of the treatment process from the remaining layers and can optionally be returned and reused; on the other hand, the coke used as a filter layer during the heat treatment can be used in the blast furnace as a l~Jlc,Cts,~ of other coke materials.
In a further alternative method, with a directed displacement of the pollutant profile in the direction of the profile of the exhaust gas temperature and especially by overlapping the correspondin~q profile maxima, the pollutants are col,c~"ll,~lt,.l onto the section of the device in which the exhaust gas temperature is especially high. The purification of exhaust gases can thus be limited to a correspondingly short section of the treatment area in which the pollutant collcell~l.9i~ll and exhaust gas temperature are at a maximum. In this manner, purification devices of a small capacity are sufficient in order to operate the entire treatment device with very low pollutant emission.
The di:~Jldctelllelll of the pollutant cul,ce,,ll~;vll profile is achieved by enriching the treatment bed with pollutant-adsorbing media which retain the pollutants until the last section of the g ` ~ 218484~
treatment area (for example the sintering apparatus) is reached.
Oniy at the end of the treatment area when the capacity of the pollutant-adsorbing medium is depleted and the combustion zone reaches the lower layers in which the pollutants are retained at high collce~ ;lLiulls the cunce~ iull of pollutants within the exhaust gas rises greatly. This portion of the exhaust gases which is greatly pollutant-loaded can then be cleaned separately.
Instead of introducing additional pollutant-adsorbing media into the treatment bed it is possible to use media with improved ~:,oruli~n properties in ~ ~ ul1S in which the treatment process requires the use of pollutant-ad~u,L,e"l media within the treatment bed. A greater specific surface area of the individual adboruliol~ medium particles can for example lead to the desired ~i_,,lacul"e,l~ of the pollutant uul~c~ Livll profile.
Advantageously the pollutant-ads~ "L media are mixed well with the material to be treated and are then poured onto the grid before they are introduced into the treatment area. It is thus possible SULJ~ldl lli..'l~ without any technical expenditure to uniformly distribute the pollutant-adsorbing media within the treatment bed.
In a further development of the invention it is su~gested 21~4843 that the pollutant-adsorbent media are provided within the lower area of the treatment bed in a higher cullc~rllli~liu" than in the upper area of the treatment bed. Varying collc~"l,~ n ratios between the pollutant-adsorbent media and the material to be treated can be produced during mixing. In order to produce an especially steep conct~r~ " I profile of the pollutants, it is favorable to gradually increase the ~oncel ,11 iiliull of the pollutant-adsorbing medium from the top to the bottom within the treatment bed. Instead, it is also possible to provide a plurality of two layers with different c~llce"lliilioll ratios.
A preferred ~IllI.odi,,,~,,l is ull~ ttli~t:d in that the collected exhaust gases are catalytically purified by employing their own high temperature. An effective catalytic purification is possible only at temperatures above 300 C. By overlapping the pollutant ~unce~ lioll maximum with the temperature maximum the required high temperature for the catalytic cleaning is achieved in most heat treatment processes. It is not necessary to provide additional heat energy; instead, the heat energy released by the process of heat treatment is collected and is suffficient as a heat source. It is furthermore advanta~eous, that the heat is not returned into the surroundings as waste heat. By catalytic ~78484~
puriflcation different pollutants can be removed from the exhaust gas. For example, ul llul Uolydl ~ic substances such as dioxins and furanes can be reduced with suitable reduction catalysts. Also, nitrogen oxides can be reduced without problems in this temperature range. A catalytic oxidation is, for example, also possible for pollutants such as SO2; SO2 is oxidized to SO3.
As an advantageous embodiment of the invention it is suggested that the pollutant-adsorbent media and their ~ul Ice, ,11 d~iUI 1~ within the treatment bed are selected such that the cul Ice, ,1, dliul I profile of the pollutants resulting within the treatment process and especially their maximum are overlapped within the end section of the treatment zone. The more CullC~Illldliol, profiles of different pollutants are overlapped and the steeper the .ullCell~l~Liull peaks are, the lower the partial volume of the exhaust gas to be purified will be and the more effective the inventive method will operate.
In a further development the exhaust gases exiting from the treatment bed in the last phase of the process are subjected to a particle sepdl d~iOll step. For this purpose, a conventional electric filter can be used. In order to achieve an especially high cleaning effect it is favorable to arrange downstream of the particle 218~843 separation a catalytic purification device.
Instead of the particle separation the exhaust gas can be cleaned with a.l~o, ~ media and water after catalytic purification. This is performed, for example, with the aid of a spray dryer with which carbon-containing adsor,uliull material in the form of dust and water are introduced into the exhaust gas stream. The introduced water reduces the exhaust gas tempsrature to such an extent that, for example, salts and chlorides will crystalize. In order to further improve the quality of the exhaust gas, instead of a spray dryer, or in addition to it, an active coke device can be used.
Advantageously, the exhaust gas is subjected to a particle sepdlaliul1 after cleaning with a-iso,,.Liùl~ medium and water.
A portion of the solid materials collected in the particle s2pdldliun step can be returned and used again as an adaur~uliull medium for cleaning. Since the ad~ull~ medium-containing solid materials have not cu~ t~ly exhausted their a~sul~ ull capacity for pollutants during their first run through the exhaust gas, it is possible by returning it to l~ad the a.l~o"u~ medium with pollutants up to its capacity limit and to thus reduce the operation costs. -13 --2~ ~fi~6F3 Advantageously the pollutant~adsorbent means is a carbon-cul"~i"i,ly flowable material for example coke fines and/or active coke. This material is i, ~ ellsive. In heat treatment processes above the ignition temperature of coke fines it will ignite and will release its combustion heat as additional heat into the treatment bed. No interfering foreign substances will remain within the treatment bed.
Preferably the inventive method is used during sintering of metallic materials.
Expedient devt~l.,,u" ,el,ts and embodiments of the invention are defined in the dependent claims.
In the following the invention will be explained in more detail with the aid of the drawing in which s~ ", ~y s~llLt~d ~Illbodi,ll~,,LO are shown. It is shown in the drawing:
Fig. 1 a schematic It~ Sellldli~l~ of a sintering ~y~ e~l for p~rullllillg a first sintering method according to the invention;
Fig. 2 a schematic l~p~se~ldli~ of a sintering d"d"g~",el,L for performing a second inventive method alternative;
Fig. 3 a schematic representation of a sintering . ~ 2~84843 d,l~l,gt""~"l for performing a third inventive method alternative;
Fig. 4 a schematic representation of a sintering for performing a fourth inventive treatment method;
Fig. 5 a schematic representation of a sintering arran~ement for p~,rul",i"g a fifth inventive method alternative;
Fig. 6 a schematic l~pl~se,,ld~iull of a sintering a"~ "el" for performing a sixth inventive method ~ ; "~t; ~ c;
Fig. 7a a schematic repl~s~,,ld~iùll of a sintering tll 1~1 ,~e" ,el ,~, Fig. 7b a diagram of exhaust gas temperature, plotted as a function of the length of the sintering band;
Fig. 7c a diagram of the exhaust gas collcel ,I, ;~liull of SO2 plotted as a function of the length of the sintering band;
Fig. 7d a diagram of the exhaust gas concentration of polychlorinated dibenzodioxins and .
-2~ ~4~4~
polychlorinated~dibenzofuranes, plotted as a function of the length of the sintering band;
Fig. 7e a diagram of the exhaust gas ,ullCt~ 1 d~iOl~ of nitrogen oxides, plotted as a function of the length of the sintering band.
The ~I ~ ,L~odi" ~"~ of the invention scl1e" Id~iC~lly I ~ 5~ d in Fig. 1 differs from the conventional sintering d"d"ge",~"~ of Fig. A on the one hand due to its second ignition furnace 4 which is arranged in the vicinity of the exit end of the sintering device 1 and which ignites the sintering bed from the underside and on the other hand by a device for g~ l d~il 15J a pressure gradient in the counter direction, i.e., from the underside of the bed to the upper side. This pressure gradient gel1~ld~i"~ device Colll~ 5 an exhaust removal hood 6 and a suction pump 10 co""~.,t~d to a return line 8.
The exhaust gas removed via the removal hood 6 can be freed of dust with a suitable filter 12. In a mixer 14 the exhaust gas is mixed with the combustion air required in the sintering device 1 at the forward, respectively, central area and is introduced together with the combustion air via the hood 16 from the top to the bottom through the sinter bed. Upon pel1~lldLillg the 2li ~84~
combustion zone, respectively, the high temperature of the sinterbed through which the combustion zone migrates, the olool!Jdlli~ substances are destroyed sufficiently and reliably.
Behind the combustion zone the exhaust gases newly formed during sinterin3, respectively, the returned exhaust gases pass through the sinter mixture in which the fuel cullL~illi,lg a great amount of carbon, in general the form of coke fines, is finely distributed. This fuel acts as an adsorption medium in which a substantial portion of the pollutants, similar to the conventional secondary purification of the exhaust gases in active coke reactors, is adsorbed In the schematic drawing according to Fig. 2 only the feeding section of the sinter bed transport device 5 is s~ e",d~ 'ly ,~ se"'~i. Othen~ise, the sintering arld"g~",e,ll corresponds to the one of Fig. A. As can be seen, the sinter band 7 has arranged thereat in sequence three feeding devices. With an additional first feeding device 18 a thin a i~ol,ulioll medium layer 20 is applied to the grid. Do~ d"~ of the device 18 the feeding device 15, as already described in connection with Fig. A, for feeding the finished sinter layer 22 onto the a~ liol I medium layer 20 is arranged, and du~ a~ thereof the feeding device 21 ~4843 9 for feeding the sinter mixture 24 which forms the actual sinteringbed is arranged. During the sintering process the f nished sinter layer 22, which may be aiso comprised of another material with sulJ~Idl llidlly inert properties, provides a temperature barrier which prevents a migration of the combustion zone into the filter layer 20 of adsorptive capacity.
Fig. 3 shows a sintering all dl~yc" ,ent which is principally of a similar design as the one of Fig. 1. However, in the rearward area the sintering a, Idl1g~",e"l 1 lacks the second ignition furnace 4. Similar to the dl I dl~gd" ,e~ I~ of Fig. 1, an exhaust gas collecting device 6' is provided which however is arranged at the underside of the sintering bed for producing a conventional pressure gradient. The collected exhaust gas is returned via the return line 8 and the suction pump 10 to the mixing device 14, is mixed with combustion air, and introduced via the hood 16 in the forward and central area of the sintering device into the sintering bed. The purification effect of the sinter mixture on the other side of the combustion zone within the sintering bed is taken advantage of with this arrangement according to Fig. 3. The investment costs are lower especially because the second ignition device is obsolete and, furthermore, because the additional f Itering device 2 1 84~43 12 can be omitted.
The previously described primary exhaust gas cleaningmeasures can also be combined. For example, the exhaust gas return according to Fig. 3 can also be used when using the additional a.lbo"uliulI medium layer 20 of Fig 2. Fu~ ull"ul~, the exhaust gas can be returned to the ignition furnace or to the inlet area, respectively, central area of the sintering device external to the ignition furnace. Also, it can be introduced in cùll,bi, IdliUI1 into the ignition furnace area and a further area, for example, into the central area of the sintering device. Upon return of the exhaust gases only into the ignition furnace, the mixer 14 andlor the hood 16 can be omitted. In respect to the sinter bed conveying device no limitations are necessar,v in connection with the invention. The conventional sinter band device can, for example, be replaced by a so-called pusher type furnace in which the sinter bed is moved in sequentially arranged baskets and is pushed through the sintering device 1. The conveyor belt can be a continuously as well as a discontinuously driven belt.
In the device according to Fig. 4 the feeding device 9 serves for feeding not only the sinter mixture but also an additional adsorption medium. The sinter mixture is ,o"".rib~d in a manner ~ .
~78~843 known per se of ores, flux material, fuels, especially coke fines,quick lime, and return material of the sintering process itself. The adsorption medium is carbon-~o"ld;"i"g and granular, respectively, flowable.
By enriching the sinter bed with adsorption media, pollutants developing within the forward or central area of the centering device 1 are adsorbed to a greater extent. The pollutants are retained within the sintering bed so that the exhaust gases removed within the forward sections already comprises sufficient purity. The exhaust ~ases removed within the forward and central areas of the sintering devices with the exhaust gas removal device 11 (removal line 25), after particle separation with an eledric filter 25', can be introduced without further purification steps into the surrounding ~ us~ul~e~. The exhaust gases removed by the exhaust removal device 11 within the rearward area of the sintering device 1 are guided via a separate removal line 26. In this area of the sintering device the temperature of the exhaust gases is naturally very high. By enriching with pollutant-adsorbing media, the Cul l~ iol~ maximum of all critical pollutants, for example, possible ~,I llul uo, ~a"ic substances, nitrogen oxides, and sulfur dioxide are located within this rearward .
~ 2~8484}
area. Particles such as fly ash are separated with t~le electric f Ite!27 from the exhaust gas. Subsequently, the exhaust gasses are catalytically cleaned by adding reduction media. Within the catalytic cleaning reactor 28 the optionally present dioxins and furanes as well as nitrogen oxides are reduced by the reduction catalyst. An additional oxidation catalyst serves to oxidize SO2 to S03. The catalytic treatment is favored by high exhaust gas temperatures. The catalytically cleaned exhaust gas can then be released without further cleaning steps into the surrounding ~ti"ob~ e,~ (removal line 29).
The fifth embodiment represented in Fig. 5 of the inventive s~lld~lgelllellL differs from the one of Fig. 4 by a purification d"~ l"er~l dU...lSIl~dlll of the exhaust gas removal line 26. In this ~ :l l IL,o-li,, ,~I II the catalytic cleaning reactor 28 is directly loaded with pollutant-loaded exhaust gases. Subsequently, the exhaust ~ases are cleaned in an d.l~l,uIiul1 medium reactor 30, with addition of adsoll,Iiol, media and water, from sulfur oxides, dust, and organic substances. A fabric filter 31 arranged do.."~ d,l, of the ad~o"uIiul1 medium reactor 30 separates the adsorption medium and further solid material from the flue gas stream. The filtrate is partially returned via the return line 32 into the reactor in 2~84843 order to adsorb more pollutants therein and in order to completelyexhaust the adbor~ capacity of the particles.
Do.~.lsLI~,,, of the fabric filter 31 the exhaust gas has relatively high purity and can be returned together with the exhaust gas from the exhaust gas line 25 into the surrounding ~I",ob~ e,~. The exhaust gas in this ~",bodi,l,e"l fulfills the more stringent pollutant emissions limits and is especially enYi, ul ~ ,t ~I:y friendly.
The employed d,lbor,uli~," medium reactor 30 can be of a very small size because by concentrating the pollutant release within the rearward area of the sintering area only a small portion of the exhaust gas removed during the heat treatment process must be cleaned from the pollutants. The constructive expenditures are thus minimal. By returning the absorption medium into the reactor the operating cost are kept at a minimum.
In the ~",I,odi,l,e"l according to Fig. 6 the removal line 26 is flrst introduced into the electric filter 27 in which solid particles especially fly ash are separated. The actual cleaning is again carried out in the catalytic cleaning reactor 2~ at temperatures of dpf.l ~ 'y 300 to 400 C. Subsequently the hot exhaust gas ~ 2~ 8~8~3 is returned via a return line 33 into the ignition furnace. Here theexhaust gas is mixed with combustion air and returned into the sintering bed. The cleaning effect of the sinter mixture positioned doL~ l of the combustion zone within the sintering bed is taken advantage of in order to achieve an even higher purity of the exhaust gas.
The disclosed exhaust gas purification measures can also be combined. For example, the exhaust gas return according to Fig. 6 can also be used in addition to adso"uliull medium reactors.
Furthermore, the adsù",': 1 medium in the lower layer of the sintering bed can be introduced in higher ~ullC~ iDll than in the upper layers. The adsorption medium and the sinter mixture can also be applied onto the band in sequence. A separate adso~liull medium layer can be provided, separated by an isolation layer from the sinter mixture. Such an a.l~,,uliul~ medium layer can also be used in addition to an ~ lll of the material to be treated with adsorption material.
The ddsol,uliun medium itself can be a flux material and/or a material mixture used in conventional sintering processes, whereby its pollutant-adsorbent properties are improved in the spirit of the present invention. It is important that the ~84843 Co~ r,~, dliOIl profile of the pollutants is displaced according to the exhaust gas temperature profile. This will be explained in more detail with the aid of Fig. 7.
The sintering process begins below the ignition furnace 3.
The sinter band 7 moves in the direction of conveyance which is to the right in the shown drawing. With the conveying movement of the sinter bed the sinter zone moves simultaneously from the top to the bottom through the sinter bed.
Fig. 7a shows a diagram of the exhaust gas temperature plotted as a function of the sinter band length. The solid line ,~p,~:,e"~ the curve for a conventional sintering process and the dashed line lezl)~se~t~ the curve for the inventive method. This is true also for diagrams b-e. The curve of the exhaust gas temperature shows in the rearward area of the sintering device a strong maximum in the conventional as well as the inventive method. The course of the temperature is practically not affected by the invention.
Fig. 7b shows the diagram of the ~ollC~ dli~l~ of SO2 in the exhaust gas plotted as a function of the sinter band length.
In known sintering processes (solid line) the SO2 c~n~ ldlioll within the exhaust gas rises shortly behind the center of the ~ ~ 4 218~843 sintering device. The SO2 peak is very broad. The exhaust gasCo~ ldliùl\ of SO2 in the inventive method is constantly ri~d"LIy lower in the forward and central areas and rises sul~:~ld~ lly only at a later point with relatively steep flanks. The peak is displaced to the rear and su~sld,lli~'ly smaller.
In Fig. 7c the exhaust gas uull~el ~1~ dliOIls of polychlorinated dibenzodioxins and dibenzofuranes is plotted as a function of the sintering band length. In the conventional sintering process the ol)ce~ dliUIl of the ~ luruul ydlli~, substances rises already at the center of the sintering process. The peak is very broad in analogy to the peak of the SO2 exhaust gas ~;ullu~l 1ll dliun. In the inventive method the exhaust gas loading with ulllo~ uu, Udl Ik, substances in the forward and central areas is suLbldll" "y lower due to the a-l~or,u~ioll effect of the sinter bed, and the maximum is displaced by forming a sharp peak to the rear.
In Fig. 7e the exhaust gas col,cel,lldliulls of NOx is plotted as a function of the sinter band length. In the conventional sintering process the NOX COll~ll[ldliOIl is sul,~ld"li..lly constant over the entire length of the sintering band. Only at the end of the band the NOX drops s~b~ldl lli.~'ly linearly. This nec~ssi'.~'_d in the past a cleaning of the entire exhaust gas volume for removal of ` ~ 2~84843 NOx pollutants. The exhaust gas~concentration of NOx in theinventive method is negligibly low in the forward and central areas and rises to a peak only in the rearward section of the sinter band.
Thus, with the inventive method it is thus possible to concentrate the pollutants within the rearward area of the sinter band. The pollutant peaks are displaced to the rear and the col~ce~ l maxima coincide with the maximum of the exhaust gas temperature. In this manner, only a small portion of the resulting exhaust gas volume must be purified. The partial amount of exhaust gas to be cleaned is collected within the rearward area of the sintering device, i.e., at a location where the exhaust ~as temperature is sul,~ '!y within the optimum temperature range required for catalytic purification.
Various alternatives are possible with the invention.
Especially, the measures represented in Figures 1 to 6 can be combined in any desired fashion. The method is suitable for a plurality of heat-treating methods with similar advantages, especially also for roastin~ methods, for example, for the heat treatment of metal sulfides, especially lead, zinc and nickel in oxidizing ~I",o~phel~s.
Claims (23)
1. Method for heat treatment of flowable material to be treated in a treatment bed, especially for sintering metallic materials with addition of fuels containing a great amount of carbon, whereby the material to be treated is poured onto a movable grid in a predetermined minimum layer thickness;
the grid with the treatment bed is moved through a treatment area and the treatment bed upon entering the treatment area is ignited at a first side;
subsequently a combustion zone extending from the ifnition side is formed within the treatment bed by providing oxygen and a pressure gradient from the ignition side through the treatment bed; and the combustion zone is displaced in the course of the further transport of the material to be treated under the influence of the pressure gradient in the direction of a second side opposite the first side of the treatment bed in order to successively heat-treat the material to be treated whereby exhaust gases exiting from the treatment bed are removed, characterized in that a counter combustion process is started by igniting the material to be treated from the second side of the treatment bed, subsequent to transporting the treatment bed by a predetermined length within the treatment device and subsequent to the combustion zone having reached a certain depth of penetration within the treatment bed, but before the combustion zone has penetrated to the second side of the treatment bed; and the treatment bed at the second location of ignition is subjected to an oppositely acting pressure gradient so that starting from the second side a second combustion zone is produced which is driven through the treatment bed to such an extent that in it the fuel particles which have not been burnt with the first combustion zone are combusted and the entire treatment bed is sintered through.
the grid with the treatment bed is moved through a treatment area and the treatment bed upon entering the treatment area is ignited at a first side;
subsequently a combustion zone extending from the ifnition side is formed within the treatment bed by providing oxygen and a pressure gradient from the ignition side through the treatment bed; and the combustion zone is displaced in the course of the further transport of the material to be treated under the influence of the pressure gradient in the direction of a second side opposite the first side of the treatment bed in order to successively heat-treat the material to be treated whereby exhaust gases exiting from the treatment bed are removed, characterized in that a counter combustion process is started by igniting the material to be treated from the second side of the treatment bed, subsequent to transporting the treatment bed by a predetermined length within the treatment device and subsequent to the combustion zone having reached a certain depth of penetration within the treatment bed, but before the combustion zone has penetrated to the second side of the treatment bed; and the treatment bed at the second location of ignition is subjected to an oppositely acting pressure gradient so that starting from the second side a second combustion zone is produced which is driven through the treatment bed to such an extent that in it the fuel particles which have not been burnt with the first combustion zone are combusted and the entire treatment bed is sintered through.
2. Method for heat treatment of a flowable material to be treated in a treatment bed, especially for sintering metallic materials with addition of fuels containing a great amount of carbon, whereby the material to be treated is poured onto a movable grid in a predetermined minimal layer thickness;
the grid with the treatment bed is moved through a treatment area and the treatment bed upon entering the treatment area is ignited at the first side;
subsequently a combustion zone extending from the ignition side is formed, within the treatment bed by providing oxygen and a pressure gradient from the ignition side through the treatment bed; and the combustion zone is displaced during the course of the further transport of the material to be treated under the influence of the pressure gradient in the direction to a second side opposite the first side of the treatment bed in order to successively heat-treat the material to be treated whereby exhaust gases exiting from the treatment bed are removed, especially according to claim 1, characterized in that the exhaust gases, exiting at least in one phase of the treatment process from the treatment bed, are collected and returned, preferably together with the gases required for ignition, upon ignition of the treatment bed in order to destroy pollutants within the ignition zone and/or within the combustion zone when flowing through the treatment bed under the influence of the pressure gradient and/or in order to adsorb them within an adsorption layer provided within the treatment bed.
the grid with the treatment bed is moved through a treatment area and the treatment bed upon entering the treatment area is ignited at the first side;
subsequently a combustion zone extending from the ignition side is formed, within the treatment bed by providing oxygen and a pressure gradient from the ignition side through the treatment bed; and the combustion zone is displaced during the course of the further transport of the material to be treated under the influence of the pressure gradient in the direction to a second side opposite the first side of the treatment bed in order to successively heat-treat the material to be treated whereby exhaust gases exiting from the treatment bed are removed, especially according to claim 1, characterized in that the exhaust gases, exiting at least in one phase of the treatment process from the treatment bed, are collected and returned, preferably together with the gases required for ignition, upon ignition of the treatment bed in order to destroy pollutants within the ignition zone and/or within the combustion zone when flowing through the treatment bed under the influence of the pressure gradient and/or in order to adsorb them within an adsorption layer provided within the treatment bed.
3. Method for heat treatment of a flowable material to be treated in a treatment bed especially for sintering metallic materials with addition of fuels containing a great amount of carbon whereby the material to be treated is poured onto a movable grid in a predetermined minimum layer thickness;
the grid with the treatment bed is moved through the treatment area and the treatment bed upon entering the treatment area is ignited at a first side;
subsequently a combustion zone extending from the ignition side is formed within the treatment bed by providing oxygen and a pressure gradient from the ignition side through the treatment bed; and the combustion zone is displaced during the course of the further transport of the material to be treated under the influence of the pressure gradient in the direction of a second side opposite the first side of the treatment bed in order to successively heat treat the material to be treated whereby exhaust gases exiting from the treatment bed are removed especially according to claim 1 or 2 characterized in that the exhaust gases exiting in the end phase of the treatment process from the treatment bed are collected and guided together with gases required for the heat treatment in the initial and/or middle phase of the treatment process through the treatment bed in order to destroy pollutants within the combustion zone and/or to absorb them in an adsorption layer positioned downstream of the combustion zone within the treatment bed.
the grid with the treatment bed is moved through the treatment area and the treatment bed upon entering the treatment area is ignited at a first side;
subsequently a combustion zone extending from the ignition side is formed within the treatment bed by providing oxygen and a pressure gradient from the ignition side through the treatment bed; and the combustion zone is displaced during the course of the further transport of the material to be treated under the influence of the pressure gradient in the direction of a second side opposite the first side of the treatment bed in order to successively heat treat the material to be treated whereby exhaust gases exiting from the treatment bed are removed especially according to claim 1 or 2 characterized in that the exhaust gases exiting in the end phase of the treatment process from the treatment bed are collected and guided together with gases required for the heat treatment in the initial and/or middle phase of the treatment process through the treatment bed in order to destroy pollutants within the combustion zone and/or to absorb them in an adsorption layer positioned downstream of the combustion zone within the treatment bed.
4. Method for heat treating a flowable material to be treated in a treatment bed, especially for sintering metallic materials with addition of fuels containing a great amount of carbon, whereby the material to be treated is poured onto a movable grid in a predetermined minimum layer thickness;
the grid with the treatment bed is moved through the treatment area and the treatment bed upon entering the treatment area is ignited at a first side;
subsequently a combustion zone extending from the ignition side is formed within the treatment bed by providing oxygen and a pressure gradient from the ignition side through the treatment bed; and the combustion zone is displaced during course of the further transport of the material to be treated under the influence of the pressure gradient in the direction of a second side opposite the first side of the treatment bed in order to successively heat treat the material to be treated, whereby exhaust gases exiting from the treatment bed are removed, especially according to claim 2 or 3, characterized in that a multi-layer system is applied to the movable grid, comprised of a first layer of a strong adsorptive material, for example, a granular or lumpy coke or coal, a second layer positioned on top as a temperature barrier comprised substantially of an inert material, especially of completely sintered material, and a third layer of the material to be treated;
the multi layer system is ignited at the side of the third layer; and the combustion zone is allowed to migrate, while maintaining the pressure gradient present at the time of ignition, to the second layer, whereby the first layer comprised of strong adsorptive material is used as a filter layer for the exhaust gases released in the combustion zone until complete combustion of the material to be treated in the third layer.
the grid with the treatment bed is moved through the treatment area and the treatment bed upon entering the treatment area is ignited at a first side;
subsequently a combustion zone extending from the ignition side is formed within the treatment bed by providing oxygen and a pressure gradient from the ignition side through the treatment bed; and the combustion zone is displaced during course of the further transport of the material to be treated under the influence of the pressure gradient in the direction of a second side opposite the first side of the treatment bed in order to successively heat treat the material to be treated, whereby exhaust gases exiting from the treatment bed are removed, especially according to claim 2 or 3, characterized in that a multi-layer system is applied to the movable grid, comprised of a first layer of a strong adsorptive material, for example, a granular or lumpy coke or coal, a second layer positioned on top as a temperature barrier comprised substantially of an inert material, especially of completely sintered material, and a third layer of the material to be treated;
the multi layer system is ignited at the side of the third layer; and the combustion zone is allowed to migrate, while maintaining the pressure gradient present at the time of ignition, to the second layer, whereby the first layer comprised of strong adsorptive material is used as a filter layer for the exhaust gases released in the combustion zone until complete combustion of the material to be treated in the third layer.
5. Method according to one of the claims 1 to 3, characterized in that the material to be treated is placed and distributed on a substantially inert sinter material layer and guided to the location of ignition on the grid such that the ignition of the material to be treated begins at the side facing away from the inert sinter material layer.
6. Method for heat treatment of a flowable material to be treated within a treatment bed, especially for sintering metallic materials with addition of fuels containing a great amount of carbon, whereby the material to be treated is poured onto the movable grid with a predetermined minimum layer thickness;
the grid with the treatment bed is moved through the treatment area and the treatment bed is ignited upon entering the treatment area at a first side;
subsequently, a combustion zone extending from the ignition side is formed within the treatment bed by providing oxygen and a pressure gradient from the ignition side through the treatment bed; and the combustion zone is displaced in the course of the further transport of the material to be treated under the influence of the pressure gradient in the direction of a second side opposite the first side of the treatment bed in order to successively heat treat the material to be treated whereby exhaust gases exiting from the treatment bed are removed, especially according to one of the claims 1 to 5;
characterized in that the treatment bed upstream of and/or within the treatment area is enriched with pollutant-adsorbing media and that the pollutants under the influence of the pollutant adsorbent media are retained within the treatment bed such that at least in one, preferably the last phase of the treatment process, the concentration profile of at least one pollutant type is adapted to the profile of the exhaust gas temperature and especially the corresponding profile maxima of the exhaust gas temperature and of the at least one pollutant type are overlapped and that in the exhaust gasses exiting in this phase from the treatment bed are collected.
the grid with the treatment bed is moved through the treatment area and the treatment bed is ignited upon entering the treatment area at a first side;
subsequently, a combustion zone extending from the ignition side is formed within the treatment bed by providing oxygen and a pressure gradient from the ignition side through the treatment bed; and the combustion zone is displaced in the course of the further transport of the material to be treated under the influence of the pressure gradient in the direction of a second side opposite the first side of the treatment bed in order to successively heat treat the material to be treated whereby exhaust gases exiting from the treatment bed are removed, especially according to one of the claims 1 to 5;
characterized in that the treatment bed upstream of and/or within the treatment area is enriched with pollutant-adsorbing media and that the pollutants under the influence of the pollutant adsorbent media are retained within the treatment bed such that at least in one, preferably the last phase of the treatment process, the concentration profile of at least one pollutant type is adapted to the profile of the exhaust gas temperature and especially the corresponding profile maxima of the exhaust gas temperature and of the at least one pollutant type are overlapped and that in the exhaust gasses exiting in this phase from the treatment bed are collected.
7. Method according to one of the claims 1 to 6, characterized in that the pollutant-adsorbent media are mixed with the material to be treated and are poured onto the grid before they are introduced into the treatment area.
8. Method according to one of the claims 1 to 7, characterized in that the pollutant-adsorbent media are present in the lower area of the treatment bed in a higher concentration than in the upper area of the treatment bed.
9. Method according to one of the claims 1 to 8, characterized in that the collected exhaust gases are catalytically purified using their high temperature.
10. Method according to one of the claims 1 to 9, characterized in that the exhaust gases exiting in the last phase from the treatment bed are subjected to a partial separation which is preferably upstream of the catalytic purification.
11. Method according to claim 9 or 10, characterized in that the exhaust gas after catalytic purification is purified with adsorption media and water.
12. Method according to one of the claims 1 to 11, characterized in that as a pollutant-adsorbing medium carbon-containing, flowable material, for example coke fines and/or active coke are used.
13. Arrangement for heat treatment of granular, respectively, flowable material to be treated, especially for sintering metallic materials with addition of fuels containing a great amount of carbon, with a treatment device (1), a treatment bed transporting device (5) comprising a band (7) for transporting the treatment bed on a grid substantially horizontally through the treatment device, a device (9) for feeding the material to be treated (24) onto the grid before entering into the treatment device, an ignition furnace (3) in the area of the inlet of the treatment device for igniting the treatment bed at a first side, and an exhaust gas removal device (11) acting on the second side opposite the first side of the treatment bed;
characterized in that at the exit end section of the treatment device (1) a second ignition furnace (4) is arranged which ignites the treatment bed at its second side; and in the area of the second ignition furnace a separate pressure differential generating device (6, 8, 10) is effective which generates a pressure gradient from the second to the first side of the treatment bed.
characterized in that at the exit end section of the treatment device (1) a second ignition furnace (4) is arranged which ignites the treatment bed at its second side; and in the area of the second ignition furnace a separate pressure differential generating device (6, 8, 10) is effective which generates a pressure gradient from the second to the first side of the treatment bed.
14. Arrangement for heat treatment of granular, respectively, flowable material to be treated, especially for sintering metallic materials with addition of fuels containing a great amount of carbon, with a treatment device (1), a treatment bed transporting device (5) comprising a band (7) for transporting the treatment bed on a grid substantially horizontally through the treatment device, a device (9) for feeding the material to be treated (24) onto the grid before entering the treatment device, an ignition furnace (3) in the area of the inlet of the treatment device for igniting the treatment bed at a first side, and an exhaust gas removal device (11) acting on a second side opposite the first side of the treatment bed, characterized in that three separate feeding device (18, 15, 9) are provided, a first one (18) of which pours a flowable adsorption medium (20) onto the grid, a second one (15) of which applies a non-reactive layer (22), for example, finished sinter, as a temperature barrier, and a third one (9) of which pours the material to be treated (24).
15. Arrangement for heat treating of granular, respectively, flowable material to be treated, especially for sintering metallic materials with addition of fuels containing a great amount of carbon, with a treatment device (1), a treatment bed transporting device (5) comprising a band (7) for transporting the treatment bed on a grid substantially horizontally through the treatment device, a device (9) for feeding the material to be treated (24) onto the grid before entering the treatment device, an ignition furnace (3) in the area of the entry of the treatment device for igniting the treatment bed on a first side, and an exhaust gas removal device (11) acting on a second side of the treatment bed opposite the first side, especially according to claim 13 or 14, characterized in that at least within the exit end section of the treatment device a separate exhaust gas collecting device (6') is arranged;
and a return line (8) connects the separate exhaust gas collecting device (6') with the ignition furnace (3) in order to guide at least the exhaust gas removed at the exit end section of the treatment device into the ignition furnace (3).
and a return line (8) connects the separate exhaust gas collecting device (6') with the ignition furnace (3) in order to guide at least the exhaust gas removed at the exit end section of the treatment device into the ignition furnace (3).
16. Arrangement for heat treating of granular, respectively, flowable material to be treated, especially for sintering metallic materials with addition of fuels containing a great amount of carbon, with a treatment device (1), a treatment bed transporting device (5) comprising a band (7) which transports the treatment bed on a grid substantially horizontally through the treatment device, a device (9) for feeding the material to be treated (24) onto the grid before entering the treatment device, an ignition furnace (3) arranged in the area of the inlet of the treatment device for igniting the treatment bed at a first side, and an exhaust gas removal device (11) acting on a second side of the treatment bed opposite the first side, especially according to claim 13 or 14, characterized in that at the exit end section of the treatment device a separate exhaust gas collecting device (6') is arranged;
a mixing device (14, 6) for feeding the combustion air for the entry side and/or middle section of the treatment device (1) is provided; and the mixing device is connected with the separate exhaust gas collecting device (6') in order to return and distribute the exhaust gas removed at the exit end section of the treatment device through the treatment bed.
a mixing device (14, 6) for feeding the combustion air for the entry side and/or middle section of the treatment device (1) is provided; and the mixing device is connected with the separate exhaust gas collecting device (6') in order to return and distribute the exhaust gas removed at the exit end section of the treatment device through the treatment bed.
17. Arrangement according to one of the claims 13 to 16, characterized in that at the end section of the treatment area an exhaust gas collecting device is arranged and is coupled via a first removal line (26) with a catalytic purification reactor (28).
18. Arrangement according to one of the claims 13 to 17, characterized in that a first particle separator (27), especially an electric filter, is arranged downstream of the exhaust gas collecting device within the exhaust gas stream.
19. Arrangement according to one of the claims 13 to 18, characterized in that an adsorption medium reactor (30) is arranged downstream of the catalytic purification reactor (28).
20. Arrangement according to claim 19, characterized in that a second particle separator (31), especially a fabric filter, is arranged downstream of the adsorption medium reactor (30).
21. Arrangement according to one of the claims 13 to 20, characterized in that the exhaust gas stream coming from the exhaust gas collecting device is returned via a catalytic purification reactor (28) to the ignition furnace (3) at the forward section of the treatment area.
22. Arrangement according to one of the claims 13 to 21, characterized in that a separate exhaust gas removal device for collecting the exhaust gas is arranged in the forward and middle sections of the treatment area and is connected via a second removal line (25) with a third particle separator (25'), especially in the form of an electric filter.
23. Arrangement according to one of the claims 13 to 22, characterized in that the second removal line (25) is connected with the first removal line (26) downstream of the electric filter.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4411505.9 | 1994-04-06 | ||
| DE4411505A DE4411505C1 (en) | 1994-03-31 | 1994-04-06 | Travelling grate sintering process for oxidic ore |
| DEP4431939.8 | 1994-09-08 | ||
| DE4431939A DE4431939C1 (en) | 1994-09-08 | 1994-09-08 | Method and appts. for heat treatment of materials |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2184843A1 true CA2184843A1 (en) | 1995-10-19 |
Family
ID=25935326
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2184843 Abandoned CA2184843A1 (en) | 1994-04-06 | 1995-03-11 | Method and arrangement for heat-treating a material |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0754247B1 (en) |
| CA (1) | CA2184843A1 (en) |
| WO (1) | WO1995027802A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE59710812D1 (en) * | 1997-07-24 | 2003-11-06 | Siemens Ag | sinter plant |
| GB2347940A (en) * | 1999-03-19 | 2000-09-20 | British Steel Plc | Iron ore sintering process with reduced emissions of toxic gases |
| DE102012005180A1 (en) * | 2012-03-16 | 2013-09-19 | Gkn Sinter Metals Holding Gmbh | Sintering furnace with a gas discharge device |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB852719A (en) * | 1958-05-17 | 1960-10-26 | Metallgesellschaft Ag | Improvements in or relating to the sintering of ores |
| FR1397409A (en) * | 1964-03-18 | 1965-04-30 | Penarroya Miniere Metall | Process for roasting or agglomeration of sulfur concentrates and reversible ovens for the implementation of said process |
| DE1508463B1 (en) * | 1966-01-19 | 1976-02-26 | Corson G & W H | BELT Sintering machine |
| FR2468653A1 (en) * | 1979-10-26 | 1981-05-08 | Creusot Loire | Agglomeration of ore mixts. on travelling sintering grate - where ore mixt. is baked as two separate layers, and coal may be used to replace coke in mixt. |
| FR2526044B1 (en) * | 1982-05-03 | 1989-11-24 | Siderurgie Fse Inst Rech | ORE AGGLOMERATION PROCESS AND INSTALLATION FOR IMPLEMENTING IT |
| EP0437407B1 (en) * | 1990-01-11 | 1995-03-29 | Sumitomo Metal Industries, Ltd. | Method for sintering fine iron ore using dual ignition system |
-
1995
- 1995-03-11 EP EP95913086A patent/EP0754247B1/en not_active Expired - Lifetime
- 1995-03-11 WO PCT/EP1995/000906 patent/WO1995027802A1/en active IP Right Grant
- 1995-03-11 CA CA 2184843 patent/CA2184843A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| WO1995027802A1 (en) | 1995-10-19 |
| EP0754247B1 (en) | 2000-08-09 |
| EP0754247A1 (en) | 1997-01-22 |
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