BE705041A - - Google Patents

Description

  

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  Method and device for the continuous manufacture of coke.



   In the process for the continuous manufacture of coke according to the main patent, the material to be coked is subjected, in successive stages, to drying, preheating, pyrolysis and cooling by circulating gas through the material which is to be coked. moves from one stage to the next, imparting to it an advancing movement either continuous or discontinuous with stopping at each stage.

     The main patent and ... the first improvement patent describe for this purpose a device in which essentially, on a support of an endless conveyor comprises

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 ning a series of juxtaposed carriages, open upwards and provided at the bottom with a grid, it comprises a series of pairs of upper and lower fixed boxes which are open towards each other and constitute with the walls of the carriages closed reaction chambers, capable of being traversed by gases which pass vertically through the material to be treated contained in the carriages and ensure the necessary heat exchanges, while the carriages pass successively from one pair of boxes to the next pair.

   The number of pairs of boxes corresponds at least to that of the various stages of pyrolysis of the material to be coked and of the first stages of cooling of the coke, but it is possible to provide a number of pairs of boxes such as the possible stage of drying. of the material, the preheating stage thereof, as well as the subsequent cooling stage (s), can also be carried out on the conveyor in enclosures comprising pairs of boxes
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 :, 1 present invGn1on is based on the fact that we have tr (.: Nv. T possible to -tait other subjects than ehi ,, y L.7, r ...:, ...% tre transi..9 in metallurgical coke according to the prirh "i pa of ... p'-d and the device described.



  6, .t 'lW: l1.âsente invention and in accordance with the process according to the patent 3rx: oipal, is subjected to a mineral or d. ,;: nelB.n. tler minerals continuous heat treatment in t8d <. ;; 5ii's, comprising a prJchaurfa; e, 'thermal reactions,: idling and possibly a preliminary drying, par .s: / circulation of gas through the mineral matter or If the mixture of mineral matter while The material or mixture is moved from one stage to the next stage.

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   Is subjected to this heat treatment, preferably, either a mineral material which is in the form of small calibrated fragments or in granular form and then mixed with a binder to form a paste intended to be subdivided before setting the binder, or a mixture of mineral matter, advantageously agglomerated into "pellets",,
The mixture of inorganic materials may comprise, on the one hand, an ore containing an oxide, optionally a hydroxide of a heavy metal, such as iron, and on the other hand a coking carbon, the swelling power of which may be of any kind.

   It has in fact been observed that the juxtaposition of certain ores and fatty coal in an intimate mixture in the pellets strongly modifies the expansion curve of the coal, so that in the process according to the invention, coals can be used which would not be suitable for coking in a common coke oven, because they would swell excessively and exert destructive thrusts on the walls of the oven.



   It is possible to subject a heat treatment in successive stages to mixtures comprising, for example, 25 to 55% of ore and 45 to 75% of a coking fatty carbon. The different stages include, after an optional drying stage, a preheating stage capable of bringing the mixture to a temperature of the order of 250 to 300 ° C., at which the charcoal does not undergo decomposition; notable position, a stage in which the mixture is heated to a temperature of the order of 500 ° C., at which the coal is subjected to partial unapyrolysis, called low temperature, with evolution of rich gases mainly containing hydrocarbons.

   In the next stage the mixture reaches a temperature of about 1000 C, at which the coal undergoes a so-called high temperature pyrolysis with the release of a relatively lean gas,

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 essentially containing. of the hydrogen and the ore a notable partial reduction which makes it lose approximately 55 to 60% of its original oxygen. Then following several successive cooling stages by means of gases reused in the preceding stages. Products are thus obtained in which the cohesion is ensured by the carbonaceous material, more particularly by the coke finely distributed between what remains of the ore and reduced metal.

   This cohesion gives the product sufficient resistance to crushing to be able to pass it to the blast furnace for the production of pig iron.



   If the ore content of the starting mixture is relatively low, about 25-35% on 65-75% coal, a product known as "ferron-coke" is obtained.



   When one chooses a mixture richer in ore, about 45 to 55%, to which one can add besides the fatty carbon still other mineral matters, such as pulverized limestone, one obtains by the process described a product proposed in steel industry under the name of "mixed pellets".



   In a somewhat modified embodiment of the process, a mixture of ore and any carbonaceous material is treated, which cannot be coked during the operation and which may consist of lean coal, semi-coke or powder coke. advantageously in the presence of pulverized limestone.

   In this case, the ore content of the mixture can reach 85%. The heat treatment is somewhat simplified compared to the above and 'only involves, besides a possible drying stage, only preheating stages have a first brings the temperature to about
550 to 600 C and a second at around 9500C, a stage in which the temperature of the mixture reaches 1200 to 1250 C, a stage in which the ore is deprived of about 80% of its original oxygen by

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 reducing faction of the oarooned matter, as well as several stages of cooling. The product obtained owes its cohesion to the interpenetration of the ore reduced to metal and the molten gangue. It is known as "pre-reduced pellets".



   The products obtained by the process described constitute a raw material of great value for supplying blast furnaces. Their use leads to a significant reduction in the quantity of metallurgical coke required in the blast furnace, as well as a considerable reduction in the volume that the ore to be processed occupies there. In addition, materials such as mixed pellets and pre-reduced pellets have significantly better heat conductivity than coke, resulting in reduced operation time. All these factors combine to considerably increase the production capacity of blast furnaces.



   Until now the manufacture of products such as ferro-coke, mixed pellets and pre-reduced pellets has been difficult, for lack of suitable apparatus in which a neutral or reducing atmosphere can be produced. The usual coke oven batteries, although they offer this atmosphere, are not taken into account, among other things for the reason that the refractory ceramic materials constituting the coating. of its rooms, would be very quickly destroyed on contact with hot ores and by the formation of iron silicates. The process according to the present invention overcomes these difficulties by making obtaining these products technically possible.



   This process can also be extended to the heat treatment of mineral materials such as limestone, in particular limestone subdivided into small fragments, useless in the usual lime kilns. The process then comprises

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 stages of drying and preheating by means of hot gases from the thermal decomposition stage, in which the material is brought to a temperature of 950 to 1000 C by the combustion of a gaseous or liquid fuel in the presence of air preheated, as well as several stages of cooling, in which blown air passes through the material and then passes to the thermal decomposition stage where it serves as preheated secondary air.



  We could obviously achieve the decomposition temperature of the limestone by means of a carbonaceous material mixed at the start with the limestone and burnt at the decomposition stage with the aid of preheated air, in which case the lime would be contaminated by ash from carbonaceous material.



   This extension of the process according to the invention is aimed less at supplanting the current process of firing limestone in shaft furnaces than at creating the possibility of occasionally using the fine parts of the limestone which necessarily occur in all quarries, or to be able to economically exploit limestone deposits with strongly crevassed beds, providing little or no blocks suitable for the shaft furnace.



   The implementation of the method described above in several variants is done by means of a device which derives from that forming one of the subjects of the main patent and of its first improvement patent. As regards more particularly the obtaining of ferro-coke or mixed pellets, it could easily be done in the device described for the continuous manufacture of coke, but as for obtaining ferro-coke or mixed pellets. , the quantity of coking coal to be used is reduced compared to that which must be provided for the continuous manufacture of coke, it is advantageous to add to the

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 device some modifications which are included in what will be explained below.

   The various gas circuits are in principle maintained in the device, modifying the heating of the material at the stages of low-temperature pyrolysis and of high-temperature pyrolysis of the carbonaceous material always taking place by means of the gases given off during these stages. In the modified device suitable for obtaining pre-reduced pellets and for the thermal treatment of a mineral material such as limestone, the gas circuits are adapted to the fact that the operation no longer produces combustible gas and that the heat necessary for the reaction stage at high temperature must be supplied by combustion, of a gaseous or fluid fuel coming from the outside.

   In addition, the present invention also relates to improvements in details of embodiments of the device suitable either for the continuous manufacture of coke or for obtaining ferro-coke, mixed pellets or pre-reduced pellets.



   According to the invention, a modified device more particularly suitable for obtaining ferro-coke and mixed pellets, comprises six pairs of upper and lower fixed boxes on the conveyor on which the carriages loaded with pellets of a mixture. The ore and the coking carbon are periodically advanced from one stage to the next.



   The first pair of boxes is used for the drying stage of the material and is preferably provided in the lower box with a burner supplied with a gas given off in a later stage and burning in air sucked in by a fan which is connected to the upper box and rejects into the atmosphere the combustion products and the vapor mist coming from the material to be dried.

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   The second pair of boxes is used for the preheating stage. fage of the material and is supplied with an inert gas, which may consist of air progressively deprived of its oxygen, which passes in a closed circuit between this pair of boxes and the sixth pair of boxes serving for the final cooling stage, and tra - partially pours a heat exchanger in which it is in cnntact with a hotter gas, before entering through the upper box of this second pair of boxes.



   The third pair of boxes is used for the so-called low temperature carbon pyrolysis stage, releasing rich gases comprising mainly hydrocarbons which, after cooling and passing through a tar remover and removing the excess gas part, are reheated. by passing them, partly through the fifth pair of boxes serving for the first cooling of the material, or partly through a heat exchanger in which they encounter a hot gas. The gases thus heated are reintroduced into the upper box of this third pair of boxes in order to bring the mixture to be treated there to the so-called low temperature pyrolysis temperature.



   The fourth pair of boxes is used for the stage of high temperature pyrolysis of the coal, as well as for the partial reduction of the ore and comprises in the upper box burners supplied with gas produced in one or more of the stages and producing, in the presence of a minimum of combustion air, flames directed downwards to bring the material under treatment to the required temperature.

   The combustion gases mixed with the lean gases given off by the pyrolysis and with the gases resulting from the reduction of the ore, containing mono- and carbon dioxide, are collected in the lower box and brought into the heat exchanger where they are cooled and a part of which is used

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 Used, if necessary in common with a part of the rich gases, to supply the burners of this fourth pair of casings.



   In another embodiment of the device according to the invention, suitable for obtaining pre-reduced pellets, it comprises six pairs of upper and lower fixed boxes on the conveyor on which the carriages loaded with ore pellets and non-confident carbonaceous material, are advanced periodically from one stage to the next stage. The lower boxes of the third and fourth pair are connected directly to each other.



   The first pair of boxes serves as above for the drying stage of the material, but this time by means of air which has passed through the sixth pair of boxes serving for the last cooling stage, was further heated in an exchanger. of heat and is sucked through this first pair of boxes by a fan which returns it to the atmosphere.



   The second pair of boxes is used for a first stage of preheating the material and is connected in a closed circuit with the fifth pair of boxes serving for the first stage of cooling, by means of a pipe connecting the upper boxes of the two pairs of tubes. boxes and a second pipe connecting the lower boxes of these two pairs and comprising a fan which delivers a cooled neutral gas from the second pair of boxes to the fifth pair and from the latter the heated neutral gas to the second pair of boxes .



   The third pair of boxes serves 4 a second stage of preheating the material by means of hot gases which pass directly from the lower box of the fourth pair of boxes to the lower box of this third pair of boxes and are

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 evacuated from the upper box of the latter pair by first passing through the heat exchanger through which the air flows from the sixth pair of boxes and going to the first pair, and then through a heat exchanger through which the air passes. air intended to serve as preheated combustion air in the fourth pair of boxes.



   The fourth pair of boxes is used for the reaction stage between the ore and the carbonaceous material in order to reduce the ore and to melt the gangue at least partially, and comprises in its upper box burners supplied with a liquid fuel. 'or gaseous and producing flames directed downwards to bring the mixture to the required temperature, in the presence of a reduced quantity of combustion air.



   The main patent already provides for covering the material to be treated with a layer of carbonaceous material which ignites easily at the high temperature pyrolysis stage, with the effect of creating a reducing atmosphere in the bosom of the material in reaction which is traversed. by the combustion gases, and for this purpose attach a special hopper to the loading hoppers of the carriages.



   In the device suitable for obtaining pre-reduced pellets, it may be advantageous to detach this special hopper from the other hoppers and to place it above the airlock separating the third from the fourth pair of boxes and to debit the carbonated material on the hopper. material being processed as the carriages pass through the airlock when they are advanced from one pair of boxes to another.



   An embodiment of the device according to the invention, particularly suitable for the heat treatment of limestone in the form of small fragments or in the form of agglomerates of granules, further comprises six pairs of upper and lower fixed boxes on the conveyor. on which the loaded trolleys

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 are preferably advanced in continuous movement from one stage to another. The upper boxes of the third and of the fourth pair of boxes then advantageously constitute a single burner hood supplied with a fluid or gaseous fuel.



   The first pair of boxes is used for the first preheating of the material to be treated and for this purpose its lower box is connected by a pipe to the lower box of the third pair to receive hot gases, and its upper box is connected to a pipe. which leads to the outside atmosphere and includes a cyclone intended to capture the limestone dust entrained by the exhaust air,
The second pair of boxes is used for the second preheating of the material to be treated and its lower box is connected by a pipe to the corresponding box of the fourth pair of boxes to receive very hot gases, and its upper box is connected to one. pipe which goes to a material drying device arranged upstream of the conveyor,

   and comprises a cyclone retaining the dust of the limestone entrained by the gas left to the outside atmosphere.



   The third and fourth pairs of boxes are used for the thermal decomposition of the limestone by means of the combustion gases coming from the flames developed by the burners.



   The fifth pair of boxes is used for the first cooling of the material now made up of quicklime. * One of the boxes is connected by a pipe to the corresponding box of the sixth pair of boxes and the other box is connected by an outlet pipe. , in order to bring preheated combustion air, near the burners of the hood constituting the upper common box of the third and the fourth pair of boxes. Driving between the fifth and sixth pair of

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 births comprises a cyclane intended to retain the quicklime dust entrained by the air coming from the sixth pair of caissons.



   The sixth pair of boxes is used for the final cooling of the material. One of the boxes is connected to the cyclone arranged between the fifth and the sixth pair, and the other box may be provided with a blower, sucking in fresh air which will pass successively through the sixth and the fifth pair of. boxes before serving as preheated combustion air in the common hood of the third and fourth pairs of boxes.



   When this device is used for the treatment of poor limestone in small fragments, it includes a classifier screen. This is placed at the loading point of the carriages and is able to deliver successive layers of sizes of increasingly large fragments into them. The larger gauges are then found in the upper layers of the load of the carriages and are therefore exposed in the pairs of thermal decomposition chambers to the hottest combustion gases.



  Thus, the thermal decomposition of the different sizes of limestone is completed simultaneously. The too fine gauges are retained by the sieve and intended to join the dust collected by the cyclones arranged downstream of the drying apparatus, and of the pair of boxes used for the first preheating of the material.



   The conveyor of the device suitable for the thermal treatment of limestone comprises at one of its ends a motor cake driving the carriages in a continuous forward movement and, advantageously, at the other end a simple rail. curved against the rail bringing the carriages from one line to the other.

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   In all embodiments of the device, the carriages comprise a hollow frame which is capable of being cooled by injection of air and has the shape of a frame on which the bars of the grid are placed and mounted on the walls in suitably insulated sheet. The load carriages, intended to receive as load material mixed pellets, pre-reduced pellets or a mineral material capable of undergoing thermal decomposition, advantageously only have two longitudinal walls, so that the juxtaposed load carriages constitute. a continuous channel, interrupted by the intercalation of airlock carriages having four walls which are closed above, when the pairs of fixed caissons are separated from each other by an airlock,

   and the advancement movement of the carriages takes place periodically from one pair of boxes to the other. The inner faces of the walls of the pairs of fixed boxes and of the longitudinal walls of the load carriages, as well as the outer faces of the walls front of the airlock carriages, comprise a layer of heat-insulating material covered with a layer of ceramic material refractory to heat.



   Although, in the area of the pairs of fixed boxes, the advancement of the carriages is effected by sliding, rails for the rolling of the rollers of the carriages are provided and mounted on the side members by means of domed washers. These washers act as springs and can take up part of the weight of the carriages, in order to reduce the resistance to movement created by the sliding and sealing strips fixed to the upper and lower edges of the longitudinal walls of the carriages and upper and lower boxes.

   These sliding bands are advantageously provided with longitudinal grooves capable of being traversed by a cold gas. As gas, it is preferably chosen.

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 rence an inert gas released during the thermal treatment of the material and being under a pressure somewhat higher than that prevailing in the pairs of fixed boxes. Thus, the gas filling the grooves protects the reaction chambers from the re-entry of air in the event of poor sealing between the sliding strips, because the neutral gas would pass inside the chambers before the air, and in the event of a poor seal. of leakage to the outside, the neutral gas would prevent the gases in the enclosure, which may be combustible, from passing to the outside.

   For cleaning these grooves, some chariota, for example airlock carriages when they are present among the juxtaposed carriages, are provided with scraper fingers.



   When several carriages occupy a pair of boxes and are periodically moved to the next pair of boxes, it is advantageous to provide an independent advance mechanism for the cake. This mechanism may comprise screws arranged parallel to the conveyor and driven in rotation by a motor in one direction or the other and, on each screw, a cursor carrying a movable finger, able to stand up and to be placed against the. last of the carriages juxtaposed on the upper feed line of the conveyor to advance, by moving the cursor, all the carriages from one pair of boxes to the next pair when the screws turn in one of the directions of rotation, and to be lowered when the screws turn in the other direction to return the cursor to its starting position.



   This advancement mechanism frees the cake from the heavy task of moving the trolleys through the pairs of fixed boxes, which allows them to be specially designed to suit their other task of moving the trolleys through. to each other of the lines of

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 carrier, upper and lower. according to the invention, the cakes comprise a drive means in continuous rotation, as well as lock means. which stop the trains of trolleys juxtaposed in front of the downstream cake and only allow a small determined number of isolated trolleys to pass through each rotation of the downstream and upstream cakes, for example 1 to 4 trolleys.



   On the one hand, the locking means advantageously comprise cylindrical stops which are freely mounted on transverse axes fixed at the intersection of a line of advance of the conveyor and of a cake and intended to come into contact. with the rollers of the carriages being on an advance line, in order to prevent these carriages from accessing the cake.



  On the other hand, the cakes are provided around their periphery with a pair of notches for each carriage before each turn of rotation of a cake to pass over the latter. In the presence of a first notch in a cake, the front rollers (or counter-rollers) of a carriage can engage in this notch and pass under the cylindrical stops, and then the rear rollers (or counter-rollers) of the carriage in the second notch and also pass over the cylindrical stops. The carriage, thus supported by the cake, is delivered by the latter freely on the other line of advance of the conveyor *
During the passage over the downstream cake, the load carriages of a train of carriages which have left the last cooling stage must empty their contents into a hopper for receiving and crushing the treated material.

   As the load carriages do not have transverse walls and form a continuous channel between two airlock carriages, and as by the heat treatment that the material has undergone, it can be taken

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 en masse to form a single block extending over several carriages, emptying them can be difficult, irregular and sudden. The locks described above eliminate these difficulties. Indeed, the engagement of the rollers (or counter-rollers) before a carriage in the notches of the downstream cake gives this carriage an inclination with respect to the carriages which are still on the upper feed line. of the carrier.



  By this inclination, a break is initiated in the block of material, which break is transformed into a frank shear when the rear rollers (or counter-rollers) in turn engage in the notches of the bar, so that each carriage discharges part of the block of material into the receiving hopper as it passes over the downstream cake.



   At the upstream cake, the locking means are placed at the level of the lower advance line of the conveyor and allow the empty trolleys to be brought up, one by one, by the cake, which must constitute a new train of trolleys juxtaposed on the upper advancement line.



   The accompanying drawings represent by way of example several embodiments of the invention.



   Fig. 1 is a schematic view of the device according to the invention suitable for the heat treatment of "pellets" of mixtures of ores and coking coal; Fig. 2 is a schematic view of a device more especially suitable for the heat treatment of pellets of a mixture of ores and a non-coking coal; Fig. 3 is a schematic view of the device according to the invention modified for the heat treatment of a mineral material such as limestone;

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 Fig. 4 shows a vertical section through a pair of upper and lower stationary boxes between which load carriages can be moved; . Fig. 5 is a view partly in plan and partly in section of the frame of a trolley; Fig. 6 is a section taken on the line VI-VI of FIG. 5;

   Fig. 7 shows the elastic mounting of the rails on which the rollers of the carriages advance; Figs. 8 and 9 are vertical sections through the slip bands; Fig. 10 shows a mechanism for advancing the carriages; Fig. 11 shows part of a downstream cake with the individual locking means of the carriages, and FIG. 12 is a view similar to the previous one of part of an upstream cake.



   Let us first recall that the main patent and its first improvement patent relate to a process for the continuous manufacture of metallurgical coke, in which the material to be treated is successively moved through closed enclosures to undergo therein. different stages of operations such as possible drying, preheating, pyrolytic decomposition at a relatively low temperature, pyrolytic decomposition at a significantly higher temperature and successive cooling, by means of gases which pass through the material under treatment in one direction vertical, either to provide it with the necessary calories and to mix with the hot gases given off during pyrolytic decomposition stages, or to remove the calories given off during the cooling stages,

   in order to

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   reintroduced into the process in previous stages,
As explained above, the subject of the present invention is a process which extends the prior process called to the heat treatment of mixtures of mineral materials or that of non-carbonaceous mineral materials, by means of a device which is derived from that described and represented in different embodiments in the main patent and its first improvement patent. To facilitate the comparison between the latter device and that according to the present invention, the references 1 to 114 have in all cases the same meaning, and only the references from 115 are particular to the new case according to the present invention. .



   Thus, the device of the present invention comprises in the different embodiments according to Figures 1, 2 and 3, like the prior device, carriages 1 which are open at the top and provided at the bottom with a grid, and intended to receive the material to be processed. They are closely juxtaposed to each other, at least when they are on the upper feed line of a conveyor which is provided with an upstream cake 2 and usually a downstream cake 3 (Figs . 1 and 2), as well as several pairs of fixed boxes, each of which comprises, on either side of the feed line, an upper box 8 and a lower box 9. With the longitudinal walls of several juxtaposed carriages , each pair of boxes constitutes a sealed reaction chamber, corresponding to one of the stages of treatment.

   The different pairs of boxes can be attached to each other (Fig. 3) or be separated by an airlock 10 (Figs. 1 and 2) occupied by an airlock trolley closed on all sides and forming a watertight plug. . These airlock carriages are interposed at a suitable distance between the load carriages 1.

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   Near the upstream cake 2 are placed hoppers 35, 36 and possibly 37, intended to supply using metering-distributors 35 ', 36', 37 'the load carriages, the first of an inert material such as coke end to constitute on the grid of the carriages a protective layer, the second of material to be treated in the form of balls, in particular 'pellets, or in the form of calibrated fragments, and the third of an easily flammable carbonaceous material.



   The advancement of the carriages through the different pairs of fixed boxes can be continuous and controlled by the wheel 2, as provided for example in figure 3. It can however be discontinuous and advance the occupant load carriages. a pair of boxes relatively quickly to the next pair, so that groups of carriages are stopped for a desired period of time in each pair of boxes.



  In this case, it is advantageous to provide locks 10, The discontinuous advancement of the carriages can be controlled by the cake 2; but since the simultaneous advancement of a large number of carriages moving by sliding between the upper and lower caissons requires considerable effort, it is advantageous to provide a special advancement mechanism which will be described later, and which makes it possible to lighten this cake and to reserve the cake 2 and 3 for other purposes, in particular for the passage of the carriages from one to the other of the upper and lower feed lines of the conveyor.



   As explained above, one of the objects of the present invention is to obtain intermediate metallurgical products, more particularly iron and steel, facilitating and accelerating the production of the metal in the subsequent stages of manufacture, making it possible in particular to '' increase the production capacity

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   production of existing blast furnaces, while reducing the quantities of metallurgical coke required and allowing the use of coals not suitable for coking.



   Among these intermediate products are "ferro-coke" and "mixed pellets", representing at the start of "peUetized" mixtures of an ore containing for example an oxide or an iron hydroxide, of a coking coal and optionally. a filler such as pulverized limestone. For ferro-coke, which must supply the blast furnace with an appreciable quantity of metallurgical coke, the starting mixture comprises 25 to 35% of ore and 65 to 75% of fatty coal, while for the mixed pellets, containing fillers , the starting mixture contains 45 to 55% ore.

   Although these products could be obtained in a device corresponding to one or other of the embodiments described and represented in the main patent and its first improvement patent, it is advantageous to provide for this purpose a simpler device, comprising only six stages and pairs of fixed boxes, as shown in Figure 1.



   In a first stage 38, the pellets are dried by means of combustion gas produced by a burner 39 supplied with combustible gas taken from the pipe 40 and excess air.



  The combustion gases pass through the material preferably from the bottom upwards and are released to the atmosphere by a pipe 41, in which are interposed a dust-removing cyclone 42 and a suction fan 43,
The next stage in enclosure 44 is used for preheating the material to be treated to a temperature of for example 250 ° C., at which the carbon contained in the pellets next to the ore does not undergo any appreciable pyrolytic decomposition, at

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 by means of a recycled neutral gas which may be air or an oxygen-deprived combustion gas.

   To this end, a pipe 45 connects the upper chambers of a final cooling stage 46 and of the stage 44, and a pipe 47 joins the pipe 45 upstream of the gas inlet into the chamber 44. This pipe 47 passes through a downstream compartment 78 of a heat exchanger 48 traversed by very hot gas supplied by a pipe 49. At the outlet of the lower case of the enclosure 44 is provided a pipe 50 which branches off into a pipe 51 connected to a fan 52 forcing part of the gas from the pipe 50 into the pipe 47,

     and in a pipe 53 in which is interposed a fan 54 driving another part of this gas towards the lower box of the enclosure 46, where it serves as a cooling agent passing through the treated material. As the temperature of the gas leaving the enclosure 46 may be low enough at the end of a period of residence of the material in this enclosure, and insufficient to properly preheat the material to be treated in the enclosure 44, the distribution. tition of the neutral gas by the fans 52 and 54 is done so that towards the end of a period, the quantity of gas passing through the heat exchanger is considerably increased to the detriment of that delivered to the chamber 46,

     so that the normal preheating of the material is ensured in the enclosure 44 throughout the period of stopping of the carriages.



   The first pyrolytic decomposition, at moderate temperature, of the coking carbon contained in the pellets can be done in a single stage, whereas previously, where the material consisted only of carbon, two successive stages had to be provided. This first pyrolytic decomposition takes place in the enclosure 55, the upper box of which is provided with a pipe bringing very hot gases coming in part through

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 a pipe 57 connected to the upper box of the enclosure 58 intended for the first cooling of the material, and partly by a pipe 96 bringing heated gases into the upstream compartment 77 of the heat exchanger 48.

   The thermal reaction causes, in enclosure 55, to release carbon gases rich in calories mainly containing hydrocarbons. These rich gases mix with the heating gases introduced into the upper box. All of these gases leave the lower casing via a pipe 63, pass through a taring device 64 with condensed gbudron outlet 65, and are taken up by a fan 66 which discharges part of these cold gases via the pipe 96 towards the compartment 77 of the heat exchanger 48, part which enters as heated gas into the upper box of the enclosure 55,

   and another part of these cold gases via a pipe 67 in the lower box of the enclosure 58 where it heats up by passing through the material coming in the very hot state of the previous stage and then returns to the conduit 57 the enclosure 55.



  As in the latter enclosure the volume of gas increases by the freshly released rich gases, the part of excess rich gas is withdrawn and brought through a pipe 70 to a gasometer (not shown). In short, the enclosure 55 is supplied with hot gases consisting of rich, tar-free gases which pass in closed circuits, partly between the enclosures 55 and 58, and partly between the enclosure 55 and the compartment 77 of the heat exchanger. heat 48.

   The distribution of the gases between these two closed circuits can again be modified during a period of stopping the carriages in the various stages of treatment so as to ensure the continuous supply of the enclosure 55 with rich gases having the temperature. required of about 500 C.

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   At the following stage, the material coming from the enclosure 55 is brought to a temperature of the order of 1000 C, at which the coal undergoes the actual coking and the ore - a partial reduction, depriving it of 55 to 60% of its primitive oxygen. For this purpose, the upper box of the enclosure 71 is lined with burners 72 directed downwards and supplied with a combustible gas which has been produced in one or more of the stages.



  The combustion of this gas takes place in the presence of a minimum of combustion air, and the presence of a carbonaceous material as an upper layer covering the layer of pellets in the carriages, has the consequence of creating in this layer a distinct atmosphere. reducing. Various gases are released during this stage, on the one hand the products of the final pyrolysis of the coking coal, mainly containing hydrogen alongside very little hydrocarbons, and on the other hand the products of. partial reduction of the ore, containing next to carbon monoxide relatively little carbon dioxide. These gases, relatively pau-. vres in calories, compared to the rich gases given off in the enclosure! 55 above, are called lean gas in what follows.

   They leave the enclosure 71 through the pipe 49 connected to the lower box and pass as hot gases through the compartments 77 and 78 of the heat exchanger 48 and are sucked in by a fan 73 which delivers them through a pipe 40 to a gasometer. (not reproduced).



   The lean gases supply, apart from the burner 39 in the enclosure 38, the burners 72 of the enclosure 71. The rich gases can, if necessary, make up for the insufficient quantity or quality of the lean gases, which does not present any disadvantage, given that the embodiment of the invention according to FIG. 1 has as its essential aim the rational preparation of intermediate products of considerable value in metallurgy, in

 <Desc / Clms Page number 24>

 the occurrence of ferro-coke or mixed pellets, and not to produce combustible gas which can be used outside the installation.

   In all cases, it is easy to provide in the starting mixtures, in particular for mixed pellets, the proportions of coking coal on the one hand and of ore and feedstock on the other hand, in such a way that the combustible gases given off from the charcoal during its pyrolytic decomposition are sufficient to assure the process complete autonomy from the calorific point of view.



   FIG. 2 shows an embodiment of the device according to the invention, more particularly suitable for obtaining “pre-reduced pellets” starting from a “pelletized” mixture comprising up to 85% of ore, a material non-coking carbonaceous, capable of reducing high temperature ore and possibly a feedstock such as pulverized limestone.



   The device comprises, on either side of the upper advancement line of the conveyor, six pairs of upper and lower fixed boxes, the lower boxes of the third and fourth stages of which are connected directly to one another.



   For the stage of drying the pellets, an enclosure 38 is provided, the lower box of which is connected by a pipe.
41 to a vacuum cleaner 43 discharging the air used for drying to the atmosphere by passing through the carriages from top to bottom. The upper box of the enclosure 38, which includes a burner 39 serving only during the start-up of the installation, is connected by a pipe 115 to the outlet of a multitubular heat exchanger'116, the inlet of which is roconnée by a pipe 117 to the lower box of the enclosure 46 for the final cooling of the material, the upper box of which is connected to a

 <Desc / Clms Page number 25>

   blower 118 fed with atmospheric air.

   Thus, the air preheated in the enclosure 46 is heated in the exchanger 116 and enters the enclosure 38 at a temperature sufficient to dry the pellets and to bring them to approximately 200 C.



   At the next stage in the enclosure 44, the preheating of the material can be pushed up to. 550-600 C. which does not present any drawbacks since the pellets do not contain any carbonaceous material liable to undergo pyrolytic decomposition which would limit, as previously, the preheating temperature to 250-300 C.

   The lower box of the enclosure 44 is connected by a duct 119 with fan 120 to the lower box of the enclosure 58, and the upper box of the latter to the corresponding box of the enclosure 44 by a duct 121, of so that a neutral gas, for example air progressively deprived of its oxygen, can in a closed circuit heat the material in the enclosure 44 and cool it in the enclosure
58.



   The third stage, in enclosure 55, serves for a second preheating of the material to a temperature at which there is not yet a significant reduction of the ore, ie at around 950 C. The lower box receives for this purpose directly, through a passage 122, the very hot gases coming from the enclosure 71 and showing a temperature of the order of 1100 C.



   These pass through the layer of material and leave the enclosure 55 via a pipe 123 which leads them to the heat exchanger 116 where they serve as heating fluid, just like in the subsequent heat exchanger 124 which they leave under. the effect of a ventilator-vacuum cleaner 125 to gain by a pipe 40 a gasometer not shown,

 <Desc / Clms Page number 26>

 
In the fourth stage, the upper box of the enclosure 71 is constituted as a hood fitted with burners 72 developing flames directed downwards in the presence of air discharged by a fan 126, preheated in the heat exchanger 124 and brought by a pipe 127 in the combustion chamber of enclosure 71.

   The heat given off by the flames brings the temperature of the material to about 1200 to 1250 C, temperature at which the reduction of the ore is well under way and at which the gangue becomes fluid thanks to the presence of limestone transformed into lime and possibly d other substances lowering the melting point of gangue. In order to achieve a reducing atmosphere within the material, it is advantageous to place the hopper 37 and the metering device 37 ', previously attached to the hopper 36, above the airlock separating the enclosure 71 from the enclosure 55, to the effect of covering the material to be treated with a layer of easily ignited carbonaceous material only at the last moment before entering the enclosure 71.

   Thus, this layer of carbonaceous material will be very fresh when it will have to contribute to eliminating, by its combustion, the excess oxygen supplied by the combustion air, while this layer risks being partially consumed in the combustion air. previous stages if it is deposited with the load at the start of the conveyor advance line. We could also dispense with the distribution of this layer of carbonaceous material by coating the pellets during their preparation of powdered carbonaceous material.



  The reaction gases given off in enclosure 71 contain appreciable amounts of carbon monoxide and also of hydrogen. They pass successively into the enclosure 55 and the heat exchangers 116 and 124 where they each time give up a part of their value, to be used finally as fuel supplying the burners 72, if necessary alongside a supplement of

 <Desc / Clms Page number 27>

 commercial liquid or gaseous fuel. As for the pre-reduced pellets, cooled in enclosures 58 and 46 and collected on a screen 74, they contain a fine subdivision of the metal and the rest of the unreduced ore, as well as very little carbonaceous material agglomerated by the resolidified gangue and constituting a material appreciated for the blast furnace or other shaft furnaces.



   An embodiment of the device according to the invention suitable for the treatment of mineral materials liable to undergo thermal decomposition is shown in FIG. 3 showing carriages 1 juxtaposed on the upper advancement line of a conveyor. . again comprising six pairs of upper 8 and lower 9 fixed boxes with which the carriages constitute enclosures the sealing of which may be less rigorous than in the preceding embodiments, considering that the gases given off during thermal decomposition are incombustible and that the load of the carriages does not contain any carbonaceous material, In addition, the advancement of the carriages is preferably in continuous movement, provided by the upstream cake 2,

   The downstream cake can be replaced by a system 128 of curved rail and counter-rail, jointed to the right rail and counter-rail constituting the advance line, lower 129 comprising brakes 130 on which line the carriages are brought back to the cake. 2.



  The pairs of fixed boxes follow each other immediately, so that the intercalation of airlock carriages between the load carriages is unnecessary.



   As mineral material to be treated in this device, we must first of all mention the limestone in the form of small fragments not suitable for the usual lime kiln and passing for example through sieves with openings. about 30 to 40 millimeters to be retained by a

 <Desc / Clms Page number 28>

 sieve with apertures of about 5 millimeters. The menu passing through the fine screen, as well as the lime dust can be treated in the device after agglomeration. For this purpose, the fine material is converted in the presence of a binder into a paste which is extruded before drying to form agglomerates, the. calibration corresponds to that of the limestone fragments.

   Advantageously, a fairly thick lime milk, obtained using quicklime dust, is used as the binder, and the agglomerates are allowed to dry in an atmosphere rich in carbon dioxide in order to hasten the carbonation of the binder.



   The six pairs of fixed boxes comprise two pairs constituting enclosures 131 and 132 reserved for the successive preheating of the material by hot air currents, two pairs of boxes whose upper boxes constitute a heating hood 133 provided with burners 134, and whose lower boxes 135 and 136 receive the combustion gases and the carbon dioxide released, as well as two pairs of boxes constituting cooling enclosures 137 and 138 which are successively traversed by cold air delivered by a fan 139 .



   The first preheating in the enclosure 131 is done by means of gas coming through a pipe 140 of the lower box 135.



   After having passed through the material to be heated from bottom to top, these gases leave the enclosure through a pipe 141 and pass to the atmosphere through the chimney 142 after passing through a cyclone 143 with a fan. The dust retained by the cyclone passes through a pipe 144 to a fine limestone silo (not shown).



     The chamber 132 of the second preheating, having to bring the temperature of the material to 750 or 800 C,

 <Desc / Clms Page number 29>

 receives by a pipe 145, connected to the lower box. 136, the hottest gases which, after having given up part of their heat to the material to be treated, are fed through a line 146 to a dryer for the wet material, preferably a rotary kiln 147 which can be provided with an auxiliary burner 148, used during the setting up of the installation. The gases and steam mist are evacuated through a pipe 149, a ventilated cyclone 150 and a chimney 151. The dust from the cyclone 150 goes through a pipe 152 to the menu and fine limestone silo.



   The rotary kiln 147 is fed with wet limestone by a screw conveyor 153. On leaving the furnace, the dry limestone is led through a passage hopper 147 'on a screen, - classifier 154 separating the calibrated fractions from the small and fine parts which are brought by a pipe 155 towards the silo of menu and fine limestone, and delivering the fraction of finer caliber on the grid constituting the bottom of the carriages and the fractions of larger caliber on the preceding fractions of finer caliber, so that the larger fraction requiring more time to release carbon dioxide than the finer ones, or a higher temperature, will be exposed in hood 133 to the hottest gases, thereby simultaneously completing the cooking of all the sizes of the limestone.



   The burners 134, again with flames directed towards the base are supplied by lines 156 of a commercial liquid or gaseous fuel, such as fuel oil, and they receive as combustion air in reasonable excess of hot air. - Nant by a cond-aite 157 of the 'lower box of the enclosure 137 serving for the first cooling of the lime. Between this chamber and the chamber 138 of the final cooling is arranged a cyclone 158 intended to retain the dust carried by 3 * air.

 <Desc / Clms Page number 30>

 crossing the material at this last stage.

   A pipe 159 brings the dust into a fine quicklime silo (not shown), to which also ends a pipe 160 of a ventilator cyclone .161, sucking the dust released into the hopper 162 into which the trolleys discharge the quicklime as they pass from the upper feed line to the lower feed line 129. \
The object of the present invention is not only new embodiments of the device, but also modifications of the constituent elements which may relate to all the embodiments, present and prior.



   Thus, the carriages 1, previously made of a molded part of heat refractory steel, now comprise a standard steel frame, in the form of a frame 163 (Figs. 4, 5,6) with hollow 164 and openings 165, by which a current of pressurized air can be injected into the frame, with a view to its cooling, by nozzles 166 mounted on either side of the carriages on conduits 167, alternately under pressure during the stops of the carriages in the closed enclosures. The openings 165 are located below the oblique flanges 168, between two support webs 169, together forming a pump promoting the intake of outside air by the compressed air stream.



   At the level of the frame 163 are the gastts all 20 used for the advancement of the charicts on the fails 22, as well as the counter-rollers 21, integral with the frame and intended to intervene during the passage of the carriages on the cakes, and the grid bars 14 are mounted on the frame.



   The walls of the carriages consist of a sheet 170, fixed to the oblique flange 168, for example by bolts 171

 <Desc / Clms Page number 31>

   (Fig. 4 and 6), internally lined with a layer of heat-insulating material 172 and a layer of refractory material 173.



  Except in the case of the continuous coking proper and the heat treatment of mixtures of ore and carbon rich in confident coal (ferro-coke), the carriages do not have transverse walls, so that the juxtaposed carriages constitute a continuous channel, interrupted by airlock trolleys when the trolleys advance periodically from one pair of fixed boxes to the next pair (for example mixed pellets and pre-reduced pellets). The airlock carriages have four walls and are closed at the top, the transverse walls then being provided on the outside with layers of thermal insulation and refractory material.



   The walls of the upper 8 and lower 9 fixed boxes are made of a sheet 170 lined internally with layers 172 and 173, just like the longitudinal walls of the carriages.



   The lower boxes 9 are fixed on cross members 174 rivetéessur the uprights 6 of the frame, and 'comprising at the bottom a pipe 175 which is normally closed and periodically serves to evacuate the dust accumulated therein. The gas outlet pipe 12 is connected by a telescopic asbestos-stuffed connector 11 'to a pipe 11 ".



   As before, the upper boxes 8 are supported with part of their weight on the carriages, while the remainder of their weight is taken up by a counterweight or by an equivalent such as springs 31 placed between consoles 32 fixed to the uprights 6 of the frame and guide plates 33, integral with the causons 8 and sliding on the uprights 6. The springs are guided by threaded rods 34 which pass through a perforation

 <Desc / Clms Page number 32>

 threaded consoles 32 and constitute jacks making it possible to lift the box 8 with a view to detaching it from the carriages during inspection and maintenance work.

   The gas outlet pipe at the top of the boxes 8 is connected by a telescopic connection with asbestos stuffing 11 'to a pipe 11.



   In order to reduce the resistance of the advance of the carriages by sliding in line with the pairs of fixed boxes, the rails 22 are provided along the entire length of the upper advance line of the conveyor and mounted by means of domed washers 176 (Fige 7 @ and bnulon screws 177 on side members 178 incorporated in the cross members 174, in order to take up part of the weight of the carriages by the spring effect exerted by the convex washers, of which one or more superimposed pairs can be provided.



   The advancement of the carriages is effected by means of sliding bands, the bands 23 of which are arranged above the 'longitudinal walls of the carriages, the bands 24 under the frame
163 of the frame thereof, the strips 25 along the upper edge of the longitudinal walls of the lower box 9, and the strips 26 along the lower edge of the longitudinal walls of the upper box 8.

   Between the pairs of cooperating bands are advantageously interposed wear bands 179 (Figs 8 and 9)., Fixed to the bands 23 and 24 of the carriages * The bands 25 and 26 are provided with longitudinal grooves 180, in which conduits 181 lead. connected to pipes 182 for distributing neutral gas under a pressure somewhat higher than that prevailing inside the enclosures.

   This neutral gas is used to cool the sliding bands and contributes to the conservation of the lubricant inserted between these bands. In the event of leaks between the wear bands 179 and the bands 23 or 24

 <Desc / Clms Page number 33>

 towards the interior of the enclosures' only the neutral gas can enter and not the outside air, and in the event of leaks to the outside, the neutral gas prevents the gases inside the enclosures from escaping. . In order to ensure the cleaning of the grooves 180, some carriages, for example airlock carriages, are provided with scraper fingers 183, able to slide in cells 184 made in the wear layer 179, and to be pressed by a spring 185.



   As already explained, the advancement of the carriages on the upper advancement line of the conveyor can be done in the usual way by the motor cake 2, either continuously (for example Fig. 3) or discontinuously (for example Fig. . 1), but the cake must then be constructed in such a way that it can produce a very considerable force, especially in the case of discontinuous cementation which requires the movement of the carriages from one pair of boxes to the next pair in a relatively short time. short compared to the duration of stay of the trolleys in the various enclosures of for example 20 to 30 minutes.

   In the case of the use of carriages without transverse walls, rapid movement of the carriages from one stage to another is furthermore made essential by the fact that only the airlock carriages are provided with means ensuring the sealing in the transverse meaning and that these means cooperate only in the airlocks themselves.



  During the movement of an airlock trolley from one of the airlock to the other, there is therefore communication between a pair of fixed boxes and the adjacent pairs, during which a certain exchange between the gases of the different pairs of boxes can This exchange is not very troublesome if it is limited to a very small number of minutes and when the load contains no or very little coking coal. However, it would be Inadmissible when

 <Desc / Clms Page number 34>

 the load is made up either exclusively or mainly of coking coal; in these cases, only carriages with four walls can be used, each having transverse sealing means cooperating with corresponding means provided in the locks, as described above.



   A rapid periodic advancement mechanism shown in Figure 2 is shown in more detail in Figure 10.



  It comprises two threaded rods 186 having between end stops 187 and 188 a length which corresponds to that of a carriage train composed of a carriage of airlocks and the number of load carriages occupying a pair of boxes. fixed, and mounted on the threaded rods, sliders 189 provided with a finger 190 able to rise when the sliders come into contact with the stop 187 and to fold back when the sliders give against the stop 188. The threaded rods are driven rotated by a motor 191 through a speed reducer 192 and angle transmissions 193.

   They are arranged at the start of the upper line of advancement of the conveyor, parallel to the rails 22, so that the raised finger of each cursor can be placed behind the last carriage of a train loaded or ready to be loaded, for example against against the rollers 21, and attack it to move the entire line of juxtaposed carriages the length of a pair of fixed boxes, when the rods are rotated by the motor. The contact of the sliders with the end stops 188 stops the thrust exerted by the fingers, reverse the direction of rotation of the rods, lower the fingers and return the sliders to their starting point.



   To lock the carriages one by one from one feed line to the other. Cakes 2 and 3 (Figs. 2, 11, 12) perform a continuous rotation ;. They include in their rim 194 a pair

 <Desc / Clms Page number 35>

 of notches 195 for each carriage to be locked per revolution. In practice, a single pair of notches on each cake is generally sufficient since, for the complete lockage of a train of wagons, there is a period of time equal to that of parking a train of wagons. in a pair of fixed boxes.

   Cylindrical stops 196, freely mounted on a transverse axis 197 supported by, flanges 198 fixed for example on a counter-rail 199 (FIG. 11) are arranged at the intersection of a line of advance and of. a cake in such a way that they prevent the advancement of a carriage by retaining the front gaiety and forcing them to turn in place, driven by the rim 194, until the first notch 195 of the cake introduces himself. The front rollers engage in the notch and can therefore pass under the cylindrical stopper 196. Shortly thereafter, the rear rollers, engaging in the second notch, can also pass under this stopper and the carriage can to be brought by the cake.

   This lockage one by one cleans the trolleys by protecting them against any knocking. In addition, in the case of the use of carriages without transverse walls, containing the treated material solidified in a single block extending over several carriages, this lock ensures the subdivision of this block as a result of the two successive modifications of the 'inclination of the carriages when the rollers engage in the notches.

   The engagement of the front rollers causes the carriage to tilt forward (Fig. 11), causing a break through the mass, and the straightening of the carriage by the engagement of the rear rollers completes this breakage and transforms it into a straight shear. of the mass, so that by passing over the cake 3, each carriage can pour its contents in isolation onto a screen 74 (placed in a hopper, not shown).

 <Desc / Clms Page number 36>

 



   The Lower advance line, represented by a rail 129 (Figs. 2 and 3), is provided with brakes 130 which allow the carriages to advance one by one on this rail and stand alone in front of the lock at the bottom of the cake 2 ( Fig. 12). identical to the cake lock 3 (Fig.ll), but comprising between the notches 195 a protruding tooth 200, intended to ensure the rise of the rollers 20 of a carriage, retained by the counter-rail 199.



   Locking as described would give rise to rapid wear of the rollers 20 and of the encoones 195. In practice, the various tasks attributed above to the rollers for greater simplicity, are distributed between the rollers and the backings. rollers 21 (Fig. 4), not appearing in Figures 11 and 12 because their diameter is assumed to be chosen equal to that of rollers 20.



  The cooperation with the notches 195 (and the tooth 200) is assumed by the counter rollers 21 integral with the frame 163, while the role of the rollers 20 is limited to the cooperation with the cylindrical stops 196 and, of course, to the movement of the carriages. on the two advance lines and on the counter-rails 199 surrounding the cake, provided that the carriages are not supported by the cake by means of the counter-rollers resting in the notches. Where appropriate, the cakes include, in addition to the notches 195, deeper notches 195 '(Fig. 11) intended to receive the rollers 20 without the latter being in contact with the cakes.



   Of course, the invention is not limited to the embodiments which have been described and shown by way of example, and one would not depart from its scope by making modifications thereto.

 

Claims (1)

CLAIMS 1.- Process according to the main patent, characterized in that a mineral material or a mixture of mineral materials is subjected to a continuous heat treatment in successive stages, comprising a preheating, a thermal reaction, a cooling and optionally a drying preliminary, by circulating gas through the mineral material or mixture of mineral materials while moving the material or mixture from one stage to the next stage. 2. A method according to claim 1, .caractérisé in that subjecting to heat treatment a mineral in small sized fragments. 3. - Method according to claim 1, characterized in that subject to heat treatment a granular mineral material, previously transformed into pieces of the desired size by mixing it with a binder to form a paste intended to be divided before setting the binder . 4. A method according to claim 1, characterized in that the heat treatment is subjected to a mixture of mineral materials previously agglomerated into "pellets". 5. - A method according to claim 4 ,, characterized in that the mixture of mineral materials comprises an ore containing an oxide, optionally a hydroxide of a heavy metal, 6. - A method according to claim 5, characterized in that the mixture of mineral materials comprises an iron ore. 7. A method according to claim 5 or 6, characterized in that the mixture of inorganic materials comprises a coking carbon which may have any swelling power. <Desc / Clms Page number 38> 8. A method according to claim 5 or 6, characterized in that the mixture of mineral materials comprises any carbonaceous material capable of reducing the ore. 9. A method according to one or more of claims 4 to 7, characterized in that a heat treatment is subjected in successive stages to a mixture comprising 25 to 55% of ore and 45 to 75% of a fatty coal coking agent, the treatment comprising, after a possible drying stage, a preheating stage capable of bringing the mixture to a temperature of the order of 250 to 300 C, at which the coal does not undergo unstable decomposition, a stage in which the mixture is heated to a temperature of the order of 500 C, during which the coal is subjected to partial pyrolysis, called low temperature with the release of rich gases, a stage in which the mixture reaches a temperature of the order of 1000 C at which the coal undergoes a so-called high temperature pyrolysis with the release of relatively poor gases and the ore an unstable partial reduction, causing it to lose approximately 55 to 60% of its original oxygen, as well as several successive cooling stages by means of gases reused in the preceding stages, so as to obtain a product having a cohesion provided by the carbonaceous material, sufficient to be able to pass it in a blast furnace. 10.- A method according to claim 9, characterized in that the heat treatment is subjected to a mixture comprising 25 to 35% of ore and 65 to 75% of fatty coal, in order to obtain a product known as the name "ferro-coke". 11. A method according to claim 9, characterized in that the heat treatment is subjected to a mixture com-. carrying 45 to 55% ore and may contain alongside coal <Desc / Clms Page number 39> fat still other mineral materials, such as pulverized limestone, to the effect of obtaining a product known under the name of "mixed pellets", showing an increased thermal conductivity compared to coal or coke-metallurgical. 13, -, A method according to claims 4 or 5, 6 and. 8, characterized in that a heat treatment is subjected in successive stages to a mixture comprising up to 85% of ore a carbonaceous material capable of reducing the ore and possibly still other mineral materials, such as limestone sprayed, the treatment comprising, after an optional drying stage, preheating stages capable of bringing the mixture first to a temperature of the order of 550 to 600 C, and then to a temperature of about 950 C, a stage in which the temperature of the mixture reaches 1200 to 1250 C to deprive the ore of about 80% of its oxygen content, as well as several stages of cooling, in order to obtain a product known under the name of "prereduced pellets, in which the cohesion is ensured by the interpenetration of the ore reduced to metal and the molten gangue, 13. = Method according to claim 2 or 3, characterized in that limestone is subjected to thermal decomposition in successive stages with a view to transforming it into quicklime, the various stages of the treatment comprising stages of drying and preheating of the material by means of hot gases coming from 'a thermal decomposition stage in which the material is brought to a temperature of 950 to 1000 C by the combustion of a gaseous or liquid fuel in the presence of preheated air, as well as several stages of cooling in which the blown air passes through the material and then passes to the stage of decomposition where it serves as secondary combustion air <Desc / Clms Page number 40> preheated. 14.- Device according to the main patent and its first improvement patent, modified to be more particularly suitable for obtaining ferro-coke or mixed pellets, characterized in that, on the conveyor on which the carts loaded with pellets of a mixture of ore and coking coal are periodically advanced from one stage to the next stage, it comprises six pairs of upper and lower fixed boxes, the first pair of which is used for the drying stage of the material and is provided in the lower box a burner supplied with a gas given off at a later stage and burning in air drawn in by a fan which is connected to the upper box and rejects into the atposphere the products of combustion and the vapor mist coming from the material to dry, - the second pair of boxes is used for the preheating stage of the material and is supplied with an inert gas, which may be constituted by air deprived of its oxygen, which passes in a closed circuit between this pair of boxes and the sixth pair of boxes used for the final stage of cooling the material and partly passes through a heat exchanger in which it is in contact with a hotter gas, before entering through the upper box of this second pair of boxes, - the third pair of boxes is used for the so-called low temperature carbon pyrolysis stage, releasing rich gases which, after cooling with taring and removal of the excess gas part, are heated by passing them partly through the fifth pair of boxes serving for the first cooling of the material and partly through a heat exchanger in which they encounter a hot gas to be <Desc / Clms Page number 41> then reintroduced into the upper box of, this third pair of boxes in order to bring the mixture to be treated to the so-called low temperature pyrolysis temperature, and - the fourth pair of boxes is used for the high temperature pyrolysis stage of the coal as well as the partial reduction of the ore and comprises in the upper box of the burners producing, in the presence of a minimum of combustion air, flames directed downwards to bring the material under treatment to the required temperature, combustion gases mixed with lean gases released by pyrolysis and -, - ore reduction gases, containing carbon monoxide and carbon dioxide, being collected in the lower chamber and fed into the heat exchanger where they are cooled and part of which is used, where appropriate in common with part of the rich gases, to supply the burners of this fourth pair of boxes. 15.- Device according to the main patent and its first improvement patent, modified to be more particularly suitable for obtaining pre-reduced pellets, characterized in that, on the conveyor on which the carriages load pellets with a mixture of ore and. carbonaceous material, not any coking, are periodically advanced from one stage to the next stage, it comprises six pairs of fixed upper and lower chambers, of which the lower chambers of the third and fourth pair 'are connected directly to each other and of which - the first pair of boxes serves for the stage of drying the material by means of air which has passed through the sixth pair of boxes serving for the last cooling stage, has been further heated in a heat exchanger and is sucked in through this first pair of boxes by a fan which drives it back. in the air, <Desc / Clms Page number 42> - the second pair of boxes is used for a first stage of preheating the material and is connected in a closed circuit with the fifth pair of boxes for the first stage of cooling .. ment by means of a pipe connecting the upper boxes of the two pairs of boxes and a second pipe connecting the lower boxes of these two pairs and comprising a fan which delivers a cooled neutral gas from the second pair of boxes to the fifth pair and from the latter the heated neutral gas to the second pair. second pair of boxes, - the third pair of boxes is used for a second stage of preheating the material by means of hot gases which pass directly from the lower box of the fourth pair of boxes to the lower box of this third pair of boxes and are evacuated from the upper box of this last pair of boxes by first passing through the heat exchanger traversed by the air coming from the sixth pair of boxes and going towards the first pair, and then a heat exchanger traversed by air intended to serve combustion air preheated in the fourth pair of boxes, - the fourth pair of boxes is used for the reaction stage between the ore and the carbonaceous material in order to reduce the ore and to melt the gangue, and comprises in the upper box burner-; fed with a liquid or gaseous fuel and producing flames, directed downwards to bring the mixture to the required temperature, in the presence of a reduced quantity of combustion air. 16. - Device according to claim 15, characterized in that it comprises a hopper containing an easily flammable carbonaceous material which is arranged above the airlock, separating the third from the fourth pair of boxes and <Desc / Clms Page number 43> connected to this airlock, so as to be able to cover the mixture to be treated while the carriages pass through the airlock, 'with a layer of this carbonaceous material, intended to create, by igniting, a reducing atmosphere within the material. 17. - Device according to the main patent and its first improvement patent, modified to be more suitable for the treatment of limestone with a view to obtaining quicklime; characterized in that, on the conveyor on which the loaded carriages are advanced in continuous movement from one stage to another, it has six pairs of upper and lower boxes, whose upper boxes of the third and fourth pair constitute a single hood with burners supplied with a fluid or gaseous fuel and whose first pair of boxes is used for the first preheating of the material to be treated and for this purpose its lower box is connected by a pipe to the lower casing of the third pair to receive hot gases and its upper casing is connected to a pipe which leads to the outside atmosphere and comprises a cyclone intended to collect the limestone dust entrained by the exhaust air , .... the second pair of boxes is used for the second preheating of the material to be treated and its lower box is connected by a pipe to the lower box of the fourth pair to receive very hot gases, and its upper box is connected to a pipe which goes to a material drying apparatus arranged upstream of the conveyor, and comprises a cyclone retaining the dust of the limestone, entrained by the gas left to the outside atmosphere, <Desc / Clms Page number 44> - the third and fourth pairs of boxes are used for the thermal decomposition of the limestone by means of the combustion gases coming from the flames developed by the burners, - the fifth pair of boxes is used for the first cooling of the material consisting of quicklime , one of the boxes of which is connected by a pipe to the corresponding box of the sixth pair ,, and of which the other box is connected by a duct opening in order to supply preheated air, near the burners of the hood constituting the upper common box of the third and the fourth pair, the pipe between the fifth and the sixth pair comprising a cyclone intended to retain the quicklime dust entrained by the air coming from the sixth. boxes, the sixth pair of boxes is used for the final cooling of the material, one of the boxes is connected to the cyclone arranged between the fifth and the sixth pairs, and the other box can be provided with a suction blower of the fresh air from outside. 18.- Device according to claim 17, more particularly suitable for the treatment of limestone in small fragments, characterized in that it comprises a classifier which is disposed at the loading location of the carriages and capable of delivering into them. here successive layers of calibers of larger and larger fragments, so that the larger calibers are located above and are exposed in the pairs of thermal decomposition chambers to the hottest combustion gases, to the effect of simultaneously complete the decomposition of the different stone sizes <Desc / Clms Page number 45> limestone, calibers that are too fine. being retained by the screen and intended to join the dust collected by the cyclones arranged downstream of the drying apparatus and of the pair of boxes used for the first preheating of the material. 19.- Device according to claim 17, charac- terized in that the conveyor comprises at one end a motor cake driving the carriages in a continuous forward movement and at the other end a curved rail à.contre. - rail bringing the carriages from one line to the other. 20. - Device according to claim 14, 15 or 17, characterized in that the carriages comprise a hollow frame which is capable of being cooled by injection and has the form of a frame on which the bars of the grid are placed and fitted with suitably insulated sheet metal walls. 21. - Device according to claims 15, 17 and 20, characterized in that the load carriages, intended to receive the material to be treated, have only two longitudinal walls, so that the carriages constitute a continuous channel, interrupted by the intercalation of airlock carriages which are provided with four parojs and closed above, when the pairs of upper and lower fixed caissons are separated from each other by a passage airlock and when the advancing movement of the carriages is effected periodically from one pair of boxes to another. 22.- Device according to one or more of claims 14 to 21 characterized in that the inner faces of. pairs of upper fixed boxes. and the interior and longitudinal walls of the load carriages, as well as the exterior faces of the front walls of the airlock carriages, comprise a layer of heat-insulating material reopened with a layer of <Desc / Clms Page number 46> ceramic material refractory to heat. 23.- Device according to one or more of claims 14 to 21, characterized in that, along the different pairs of fixed boxes, rails for the rolling of the rollers of the carriages are provided and mounted on side members. by means of domed washers acting as springs that can take up part of the weight of the carriages, in order to reduce the resistance to movement created by the sliding and sealing strips fixed to the upper and lower edges of the longitudinal walls of the trolleys and upper and lower boxes. 24.- Device according to one or more of claims 14 to 21, characterized in that the sliding and sealing strips fixed to the upper and lower edges of the longitudinal walls of the carriages and to the edges of the upper fixed boxes and lower have longitudinal grooves capable of being traversed by a cold gas. 25. - Devices following claim 24, characterized in that some carriages, for example airlock carriages when they are present among the juxtaposed carriages, have scraper fingers intended to perform cleaning of the grooves in the sliding bands, 26. - Device according to claim 14 or 15, characterized in that it is provided with a periodic advancement mechanism of the carriages which is independent of the cake and comprises screws arranged parallel to the conveyor and driven in rotation by a motor. one way or the other, and, on each screw, a cursor carrying a movable finger able to rise and to be placed against the last of the juxtaposed carriages on the advancement line above the conveyor to make <Desc / Clms Page number 47> advance all the carriages from a pair of fixed boxes to the next pair when the screws turn in one direction of rotation, and then lower when the screws turn in the vane direction of rotation to bring the cursor back to its starting position. 27.- Device according to claim 26, characterized in that the cake, intended to pass the carriages from one to the other of the upper and lower advance lines - of the conveyor, comprise a means which drives them in rota - Continuous tion as well as locking means which stop the trains of carriages juxtaposed in front of the downstream cake and only allow a small determined number of isolated carts to pass on each turn of the downstream and upstream cake. 28. - Device according to claim 27, characterized in that the locking means of the carriages comprise, on the one hand, cylindrical stops which are mounted freely on transverse axes fixed at the intersection of a feed line. - cementing of the conveyor and of a cake and intended to come into contact with the rollers of the carriages located on a feed line in order to prevent these carts from accessing the cake, and, on the other hand, to the periphery cake, a pair of notches for each carriage in front of each round of rotation of a cake pass over the latter, so that in the presence of a first notch in a cake, the rollers (or counter-rollers) before d '' a carriage can engage in this notch and pass under the cylindrical stops and then the rollers (or counter-rollers) rear of the carriage in the second notch and also pass under the cylindrical stops, - the carriage thus being supported by the cake and delivered freely on the other feed line of the conveyor. <Desc / Clms Page number 48> 29, - Process according to the main patent in substance as described above. 30.- Device according to the main patent and its first improvement patent, in substance as described above and shown in the accompanying drawings.