EP0033284A1 - Procédé et dispositif de préparation d'un mélange minéral dans une installation d'agglomération - Google Patents

Procédé et dispositif de préparation d'un mélange minéral dans une installation d'agglomération Download PDF

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Publication number
EP0033284A1
EP0033284A1 EP81400120A EP81400120A EP0033284A1 EP 0033284 A1 EP0033284 A1 EP 0033284A1 EP 81400120 A EP81400120 A EP 81400120A EP 81400120 A EP81400120 A EP 81400120A EP 0033284 A1 EP0033284 A1 EP 0033284A1
Authority
EP
European Patent Office
Prior art keywords
hood
mixture
cake
agglomeration
slope
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.)
Withdrawn
Application number
EP81400120A
Other languages
German (de)
English (en)
French (fr)
Inventor
Michel Wallet
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Delattre Levivier SA
Original Assignee
Delattre Levivier SA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Delattre Levivier SA filed Critical Delattre Levivier SA
Publication of EP0033284A1 publication Critical patent/EP0033284A1/fr
Withdrawn legal-status Critical Current

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Classifications

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

Definitions

  • the subject of the invention is improvements to the methods of agglomeration of a mixture of ore and fuel on a grid in the form of an endless chain and an improved installation for the implementation of the method.
  • the fresh mixture composed of metallic ore, of siliceous or calcareous addition, and of various metallic or non-metallic recovery wastes is intimately mixed with the quantity of fuel necessary for the agglomeration operation and humidified in order to obtain a final mixture as permeable as possible.
  • the agglomeration installation essentially consists of a grid forming an endless chain which is driven so that its upper strand passes from an upstream end to a downstream end in front of means for the vertical circulation of an oxidizing gas consisting normally from a series of suction or supply air boxes.
  • a distributor hopper which allows the humidified mixture to be deposited in a regular layer, of varying thickness depending on the case and generally called "cake".
  • the air circulation means such as boxes placed under the chain and connected to one or more fans which make it possible to create a depression under the grid of the order of 1000 to 2000 mm CE, the ambient air is forced to up and down through the thickness of the cake.
  • the constantly renewed air then maintains the combustion started under the ignition hood.
  • the thin lit film called the "flame front” then produces a reaction zone which moves up and down as the solid fuel is consumed.
  • the primary agglomerate is then reoxidized by the renewal air.
  • the temperature of the cake which depends on that of the flame front is of the order of 500 to 800 ° C at this time.
  • the water front only disappears when the mixture has reached at least 100 ° C and if the permeability of the cake allows it. Its disappearance leads to a strong variation in the permeability of the temperature cake and the composition of the fumes.
  • the suction speed of the transfer and combustion air above the cake can be measured using a portable anemometer. There is, from the loading point to about two-thirds of the cooking - zone -, a decrease in this speed and then a gradual increase in it. This reduction in speed corresponds to the existence of the "water front".
  • the decrease in the air suction speed above the cake in the area where the "water front” exists compared to the air suction speed above the cake in the area the "water front” does not exist is of the order of 15 to 30% or more, depending on the mixtures the average temperature and depression of the caissons, and in particular the height of the mixture layer. Indeed, the greater the layer height, the longer the mixture located under the "flame front” to heat up by the hot gases resulting from the reactions and therefore the greater and longer the "water front” to disappear.
  • the water vapor formed in the upper layers condenses in the lower layer and the water front is therefore not normally removed before the hood d 'ignition unless giving the preheating hood a significant length and therefore increasing the length of the chain.
  • the goal sought by this improvement is not the elimination of the water front, but to obtain a more resistant and larger chipboard.
  • the subject of the invention is a new improvement to the agglomeration methods of ore on the grid allowing the elimination of the water front and an increase in the productivity of the grid without appreciable increase in the length thereof.
  • the combustion is carried out without inflammation tible contained in the load, almost instantaneous preheating of the latter over its entire thickness, at a temperature above 300 ° C, no suction of gases brought to a temperature of at least 700 ° C through the surface of the embankment formed by the pellets discharging from the loading hopper, the temperature of the gases sucked in and the rate of discharge of the pellets being regulated so that said pellets are dried, hardened and preheated almost instantaneously while they flow onto the surface of the embankment, without the fuel having time to ignite.
  • the device for implementing the method according to the invention comprises means for direct heating of the surface of the slope formed by the mixture pouring from the loading hopper at the upstream end of the cake, constituted by a hood with an oblique axis inclined downward in a direction substantially perpendicular to the slope and the lower part of which opens widely through an orifice covering at least the greater part of the slope, for the suction through the latter of hot gases produced inside the hood at a temperature above 700 ° C.
  • the charge is thus ignited over its entire thickness from the start of the grid. But when the mass mixture is thus ignited, there is a considerable widening of the flame front which occupies the entire thickness of the layer.
  • the flame front of a cake which normally represents 5 to 10% of its height, causes a pressure drop of the order of a third or half of the vacuum applied under the chain in order to ensure the flow and the passage of hot gases in the cake and maintain the flame front. If the entire thickness is on, a very high vacuum will be required under the chain in order to maintain productivity unless you agree to lose part of this productivity.
  • FIG. 1 schematically represents a conventional agglomeration installation comprising a continuous chain 1, the upper strand of which moves between an upstream drum 11 and a downstream drum 12 above a series of suction boxes 2.
  • a hopper 3 for loading the mixture into a layer for the formation of a "cake" 5 on the chain 1.
  • This hopper 3 is preceded by a hopper 31 of loading of a protective layer 51 of the grid and followed by a hood 32 provided with burners for lighting the surface layer of the cake formed by the hopper 3.
  • the cake is dumped, after cooking, into an unloading hopper 13.
  • the chain comprises a cooking zone A which goes from the ignition hood to a point C known as the cooking point where the "flame front" disappears after having passed through the whole of the thickness of the cake and a cooling zone B which goes from the cooking point to the downstream end 12 of the chain and which makes it possible to pour into the hopper 13 an agglomerate already cooled.
  • the porosity of the cake 5 being different during baking and during cooling, to each zone of the chain, respectively of baking and cooling, corresponds a series of boxes connected by a collector, respectively 21 and 22, and by means of 'A dedusting installation, respectively 23 and 24, to a suction fan, respectively 25 and 26, which discharges the aspirated gases either to a chimney or, possibly to a recycling circuit.
  • the installation comprises a hood 4 for preheating the slope 50 formed by the pellets pouring out from the loading hopper 3.
  • the hood 4 is shown in more detail in FIGS. 2 and 3. It is limited by an envelope in the shape of a pyramid trunk comprising a bottom 41, an upper wall 42 substantially parallel to the chain, a lower wall 43 inclined and two walls vertical sides.
  • the median plane P perpendicular to the bottom 41 is inclined with respect to the mixing slope 50 by an angle (a) equal to or a little less than 90 °.
  • the plane of the orifice 44 of the hood, constituting the base of the pyramid is parallel to the slope 50.
  • the loading hopper 3 which contains the mixture 52 is provided at its base with a distribution roller 31 which discharges the mixture onto the grid 1 in the form of a sheet 53.
  • a flap 14 of height adjustment H of the mixing layer is formed as is known, of pellets which roll from the flap 14 to the grid 1 covered with the protective layer 51 by forming an embankment 50 which, if the discharge rate of the mixture is properly adjusted according to the speed of movement of the chain, remains substantially in a fixed position, the spilled mixture being continuously driven by the movement of the chain.
  • the slope of the slope which depends in particular on the discharge rate, the particle size and the density of the pellets, remains approximately constant and, depending on the mixture, of the order of 38 to 45 ° relative to the 'horizontal.
  • a very hot gas brought to the temperature of at least 700 ° is produced inside the hood, which is therefore entirely covered with an insulating and / or refractory interior coating.
  • This hot gas can simply be formed by heating fumes or hot air having passed through the cake 5 to the desired temperature, and regulated by a circuit 212 connected for example to the last cooking box 210 or to the first cooling box. 220, so as to draw the hottest gases,
  • the bottom 41 of the hood will be provided with a burner 6 supplied on the one hand with combus gas tible by a pipe 61 and on the other hand by oxidizing gas such as air by a pipe 62.
  • This burner can be of any conventional type and opens into the hood by a diffusion plate of either circular or oblong shape. to have a width corresponding to that of the hood.
  • a suction box 26 connected either to the suction circuit of the cooking boxes by a pipe 261, or to an independent fan 27 by a pipe 262.
  • a suction box 26 connected either to the suction circuit of the cooking boxes by a pipe 261, or to an independent fan 27 by a pipe 262.
  • the oxidizer / fuel ratio must be adjusted to obtain the quantity of oxidizing fumes or not, necessary for the vaporization of the water and the heating of the mixture throughout its thickness up to 400 ° C and possibly at a higher temperature but compatible with the absorption capacity of the cake.
  • the regulation of the flue gas temperature is carried out in a conventional manner by maintaining in the hood a pressure of burnt gases very close to atmospheric pressure taking into account the absorption capacity of the cake.
  • the spraying and preheating operation of the mixture can be done without igniting the fuel it contains because the pellets regularly discharged by the distribution hopper 3 are constantly renewed and the heat exchange takes place over a very large area, the fuel normally not having time to light up.
  • the geometric exchange surface exposed to the hot fluid which depends on the particle size of the pellets and the speed and width of the chain, can be 200 to 500 times greater than that exposed to the hot fluid when the cake goes under the ignition hood.
  • the pellets roll very quickly down the slope, and are immediately covered by other pellets.
  • this geometric surface is even less than the actual surface of contact of the pellets with the flame or hot fumes, especially if they are prepared from concentrated ores.
  • the heat exchange between the wet pellets, the flame and the fumes is almost perfect and very fast.
  • the Wet pellets are dried, hardened and preheated almost instant ly year when roll front of the hood opening. Due to the regular advancement of the chain they become immobile and do not deteriorate, the largest pellets descending the slope lower than the finest, coming to accumulate above the protective layer.
  • the heat flux per m2 of geometrical surface is of the order of half that usually observed under the fume hoods. Of course, it is even lower if we consider the real surface of the pellets subjected to the flame. This flow can be increased or decreased depending on the mixture used and the preheating that one wishes to achieve.
  • the thermal quantity introduced per ton of finished agglomerate can be large, and at least 100 therms per ton of agglomerate, so that it is possible to vaporize all the water and even to preheat the mixture of agglomerate with -from 400 ° almost instantly over its entire thickness.
  • the hot fluids introduced into the hood, as well as the water vapor produced by the heating of the mixture, are sucked by the box 26 which as indicated above, will advantageously be connected by a conduit 262 to a wet or non-humid dust collector 263 and to an independent fan27. In this case the risk of corrosion of the main suction circuit will be practically eliminated.
  • the production of gaseous fluids is significant per m2 of surface area of the box 26.
  • the extraction of these gaseous fluids produced and the fumes from the feeds which pass through the cake is easy thanks to the very high average permeability of the mixture at this location.
  • the average height of the mixture to be crossed is half the height of the cake and the average permeability is therefore constantly greater than the cold permeability obtained throughout the thickness of the mixture.
  • a plate 16 seals under the chain and prevents the intake of parasitic air.
  • the temperature of the fumes drawn into the box 26 can be at least 300 ° C. so that the water front is eliminated instantly, the water contained in the mixture being vaporized at the moment the layer is formed on the grid. It is even possible to preheat at a higher temperature, without going as far as igniting the mixture, within the limit of the absorption capacity of the slope and possibly of the thermal efficiency of the exchange between the preheating fumes and mixing.
  • an auxiliary cover 33 can be placed above the cake between the adjustment flap 14 and the ignition hood 32 so as to avoid cooling of the mixture before it is ignited by suction into the box 26 of the hot fumes produced by the ignition hood 32 and extended by the cover 33.
  • the mixing cake being limited by this auxiliary cover 33 and by the longitudinal walls 34 ( Figure 3) which hold it laterally, the box 26 thus sucks all fumes produced in the preheating hood 4.
  • These preheating fumes can be isolated from the main cooking air suction circuit by the circuit 262 and, after wet treatment in a device 263, be recycled through the pipe 264 opening into a hood 265 placed downstream of the cooking point C, on the cooling zone B of the chain and in particular at the entrance to this zone, in order to accelerate the cooling of the cake 5 after baking.
  • these fumes which contain water vapor and water in fine droplets, will have a more effective cooling action than that of air.
  • FIG. 3 A further improvement is shown in Figure 3.
  • the hood 4 is mounted pivotally on a support system 45 about an axis 46, and its inclination can be changed by means of a screw has been Oriental i on 47. It is thus possible to adjust the inclination of the hood first of all in the event of variation of the inclination of the slope, but to orient the axis of the hood preferably towards the upper part of the slope so to get the best performance of the heat exchange, in par- cu l i st in the case of very large thicknesses of mixing layers.
  • a screw (or hydraulic) system 48 allows the longitudinal positioning of the hood according to the thickness of the mixing layer.
  • the mixture is discharged downstream from the outlet of the hopper 3, the feed direction of the c h a ine 1 but by changing the output of the hopper 3 , one could also reverse the direction of rotation of the distributor roller 31 to effect the discharge upstream of the hopper 3.
  • the preheating hood 40 could advantageously be of dimensions larger so as to cover not only the embankment 50 but also the sheet 53 formed by the pellets discharged by the drum 31.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Materials Engineering (AREA)
  • Environmental & Geological Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • General Engineering & Computer Science (AREA)
  • Manufacture And Refinement Of Metals (AREA)
EP81400120A 1980-01-28 1981-01-28 Procédé et dispositif de préparation d'un mélange minéral dans une installation d'agglomération Withdrawn EP0033284A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8001795A FR2474528A1 (fr) 1980-01-28 1980-01-28 Procede et dispositif de preparation d'un melange mineral dans une installation d'agglomeration
FR8001795 1980-01-28

Publications (1)

Publication Number Publication Date
EP0033284A1 true EP0033284A1 (fr) 1981-08-05

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EP81400120A Withdrawn EP0033284A1 (fr) 1980-01-28 1981-01-28 Procédé et dispositif de préparation d'un mélange minéral dans une installation d'agglomération

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EP (1) EP0033284A1 (enrdf_load_stackoverflow)
FR (1) FR2474528A1 (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2529577A1 (fr) * 1982-06-30 1984-01-06 Clesid Sa Procede et installation d'agglomeration de melanges mineraux
EP3088825A4 (en) * 2013-12-23 2016-12-28 Posco DEVICE FOR PRODUCING SINTERED ORE AND METHOD FOR PRODUCING SINTERED ERZ THEREWITH

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104456541A (zh) * 2014-12-04 2015-03-25 安徽诚铭热能技术有限公司 空气单预热一体式烧结点火炉

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE655490C (de) * 1936-05-28 1938-01-17 Roechlingsche Eisen & Stahl Verfahren zum Stueckigmachen von Feinerzen oder anderen Ausgangsstoffen

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1048766A (fr) * 1950-06-05 1953-12-23 Allis Chalmers Mfg Co Perfectionnements relatifs à un procédé et appareil pour la production d'aggloméés durcis à la chaleur
FR1215231A (fr) * 1958-11-12 1960-04-15 Siderurgie Fse Inst Rech Perfectionnements au procédé d'agglomération de minerai sur grille en vue d'obtenir un aggloméré plus résistant et plus gros
BE724473A (enrdf_load_stackoverflow) * 1968-11-26 1969-05-27
DE2158317C3 (de) * 1971-11-24 1975-08-14 Hoogovens Ijmuiden B.V., Ijmuiden (Niederlande) Bandpelletisieranlage

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE655490C (de) * 1936-05-28 1938-01-17 Roechlingsche Eisen & Stahl Verfahren zum Stueckigmachen von Feinerzen oder anderen Ausgangsstoffen

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2529577A1 (fr) * 1982-06-30 1984-01-06 Clesid Sa Procede et installation d'agglomeration de melanges mineraux
EP3088825A4 (en) * 2013-12-23 2016-12-28 Posco DEVICE FOR PRODUCING SINTERED ORE AND METHOD FOR PRODUCING SINTERED ERZ THEREWITH
JP2017508941A (ja) * 2013-12-23 2017-03-30 ポスコＰｏｓｃｏ 燒結鉱の製造設備及びこれを用いた燒結鉱の製造方法

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Publication number Publication date
FR2474528A1 (fr) 1981-07-31
FR2474528B1 (enrdf_load_stackoverflow) 1984-11-02

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Inventor name: WALLET, MICHEL