MXPA00011135A - Continous metal melting process and apparatus - Google Patents

Abstract

A continuous process is provided for rapid melting of a variety of virgin and recycled ferrous and non-ferrous metals. This is accomplished by distributing the introduction of the unmelted charge materials and hence the melting heat requirements along an elongate gas-solid-liquid reaction zone within a rotary furnace, according to the distribution of heat available to effect melting. In the case of fine-sized metal charge materials, fluxes and additive reagents, this charge distribution is implemented by traversing of the nozzle jet, as directed to penetrate into the metal and slag bath from a solids injection lance, successively backwards and forwards and, in the case of coarse-sized materials, by traversing of the dischage from an oscillating conveyor.

Description

APPARATUS AND CONTINUOUS METAL FUSION PROCESS Field of the Invention The invention relates to the melting of metals and, more particularly, to a rotary kiln process and apparatus applicable to the continuous melting of predominantly metallic fillers.

Background of the Invention The known commercial melting processes have inherent processing difficulties and disadvantages only partially overcome by the improvement of design and operational practice. As an example of the melting of a ferrous material, in the melting in an electric arc furnace (EAF) of the iron and steel fragments, the unfused filler materials are heated to the melting temperature with the solid surfaces that make contact with ambient air or hot oxidant gases, which generates oxidized particulate materials and reduces production. The heat input is focused on a small area inside the oven in relation to the total area occupied by the materials of the ** -. fcM, t .. ^ - ai8t - ^ load. In addition, the carbon monoxide generated by the injection of oxygen into the metal bath is only partially burned to carbon dioxide by a subsequent combustion before leaving the EAF, and only a fraction of the heat thus released is transferred back to the load . Cupola fusion has similar disadvantages, as well as a limitation of the production of cast iron, instead of steel. As an example of a non-ferrous material, reverberation aluminum melting furnaces are widely commercially applied and focus on the location of the unmelted charge in a small area relative to the sources and a heat distribution available in the the oven. The elongated rotary melting furnaces employing a partially molten bath in which a solid charge is fed, overcome some of the above deficiencies by means of the stirring of the continuous bath and the advancing action, in combination with an efficient application of the flame towards the wall, followed by the transfer of heat from the flame to the load during each rotation of the furnace. Access for the introduction of metallic fillers, fluxes and reagents in the process, however, is only through the oven's extreme, annular openings, while the mass requirements of the process, the heat transfer and the chemical reaction of the process, are variable and distributed along the length of the zones of the reaction. As an example, when the materials of the load are introduced into a bath of molten metal partially adjacent only to the inlet opening, the unmelted material can be added, creating islands of partially melted material or the like when, at the same time, the load additional length throughout the furnace is completely melted and becomes overheated. The non-molten islands of the metal exposed to the hot furnace gases are also subject to increased oxidation and loss as particulate oxide materials. Such problems obviously represent deficiencies in the control of chemical process reactions, mass transfer and heat transfer, and may also be a restriction on the maximum production and log rates that can be obtained. It is therefore a principal object of the invention to distribute the heat requirement for the melting of the unmelted charge materials along the elongated reaction zones in accordance with the distribution of the available heat to carry out the melting, with the resulting object of quickly melting the materials of the metallic charge. - * ..-.- »... -".to........

The metallic charge materials characteristically carry varying percentages of metal oxides and other impurities such as metal oxides, other metals, other compounds, dissolved gases, other elements such as phosphorus, sulfur and the like. Fluxes and additive reagents are required as the components of the charge materials for the reaction with these impurities, in the company of the metallic charge during processing, to obtain effective process parameters and the composition of the desired final product below of the merger. Perhaps the most common example of an additive reagent is coal for the reduction of metal oxides to increase the yield of the metal and / or to allow the metal to obtain a specified range or range of the coal dissolved in the molten material. It is naturally desirable that the coal be introduced into the most effective locations to obtain the desired process reactions, such as the reaction with the metal oxides or oxygen, the emission of carbon monoxide (CO) into the furnace gases, and then effect a high degree of subsequent combustion of CO (PCD), with a good efficiency of heat transfer (HTE) towards the kiln load of the heat thus released prior to the kiln gases leaving the kiln, and for the control of the composition -M-HHÉi á-ÉW «tt-. of the product. Accordingly, it is another main object of the invention to distribute the introduction of the fluxes and the reactants along the elongated reaction zones of the process according to the distribution of the chemical reaction requirements of the process. The invention provides a process and apparatus for the continuous melting of a metal in a horizontally placed elongated rotary kiln comprising the maintenance of a bath partially molten of the metal bearing a floating slag layer in a reaction zone of the gas-solid-liquid elongated, heated by a stream of hot gas passing over the metal and slag inside the furnace; transport the materials of the solid charge comprising the metallic materials, the fluxes and the additive reagents through an end opening of the annular furnace and along the reaction zone of the gas-solid-liquid and project them downwards towards the bath; traversing the position of the projection downwards successively back and forth, whereby the location of the entrance of the filler materials into the bath is distributed along the longitudinal transverse extension, and allow the liquid metal to flow towards outside the zone of the reaction of the gas-solid-liquid by which the filling of the bath with fresh solid materials is provided. The extension or stretch - ».- .. *.

The cross section preferably comprises a larger portion of the length of the gas-solid-liquid reaction zone. When applied to granular filler materials or converted into microspheres of size less than about 3 cm, for example, DRI microspheres, granular iron carbide, pulverized mineral coal, lime, limestone crushed and sifted and the iron alloy additives, the transportation comprises suitably dragging the loading materials and propelling them by means of the pressurized carrier gases through the solids injection lance placed in cantilevered beam longitudinally within the hot gas stream in the gas-solid-liquid reaction zone and the downward projection comprises jetting the charge materials and carrier gases down from a lancet nozzle into the partially molten metal bath while striking or moving the lancet successively back and forth distributing the entrance location of the material of the load length ally along the transverse extension. When applied to larger-sized filler materials, such as recycled slag metals, raw smelting, bricks, hot iron (HBI), coal or coke -ífci ^ - - - -'- «- * * - * - * • in thick pieces, the fluxes in coarse and similar pieces, the transport adequately comprises the propulsion of the materials of the load by the oscillation of an oscillating conveyor , also placed in a cantilevered beam along the liquid-solid-liquid reaction zone, and the downward projection comprises dropping the loading materials down from a discharge edge of the conveyor, towards the bath, while The carrier is hit or moved from back to front. The process requirements usually favor loading by a combination of the oscillating conveyor and the injection lance of the solids, in which case some overlap of the transverse extensions of the lancet and the conveyor apparatus is usually desirable, in such case the invention it includes controlling the time intervals of the travel cycle and the relative positions of the lancet nozzle and the discharge edge of the conveyor to avoid interference during entry between the charge materials exiting the lancet nozzle and those which are dropped from the discharge edge of the conveyor at any instant of the pass through the common path extension. In addition, the flow velocity of the material of the load can also be varied in different ALMÉ ^ a - * - U-il * -i - ta-i. -u - ^ - ^ - A-b-iW-, positions along the transverse extension, including interruptions, to achieve the longitudinal distribution of the loading material input according to the desired process parameters. This can be done either by varying the speed of travel or, in the case of the lancet, by varying the speed of feeding the lancet. The metals usually carry surface oxides, for example, iron rust, DRI or other virgin pre-reduced materials which may also comprise a residual non-reduced metal oxide content. Also, dissolved carbon is often desired as a constituent of the product, such as with the fusion of iron and steel. The filler materials therefore typically include carbonaceous materials that carry the carbon as an additive reagent for the reduction of the oxides within the slag and metal bath, releasing carbon monoxide (CO) into the hot gas stream, which represents a fuel or unburned substance. The selective injection of oxygen into the stream of hot gases facilitates the subsequent combustion of most of this CO within the elongated reaction zones of the process, and also the heat recovery thus released by the transfer of heat in the process, direct , back to the bathroom 'iteiMimriiMim-tt? + - ........... -, ... F. ... .FF, ... .. ...._ ... i ^. », - & .. i. -i. partially melted, with a higher PCD and HTE than can be obtained by the processes of the prior art. The apparatus and process of the invention is more appropriately applied with the length of the rotary furnace further elongated to incorporate a reaction zone of the gas-liquid adjacent to the reaction zone of the solid-liquid in which the liquid metal flows and accumulates for refining reactions and adjusting the temperature prior to discharge from the oven. This zone is heated by a burner from which the products of combustion form the stream of hot gases flowing to the gas-solid-liquid reaction zone in countercurrent with the general movement of the gases. materials that escape through the annular end opening adjacent to the liquid-solid-gas reaction zone. The liquid metal can be discharged by periodically stopping the rotation of the furnace and opening a hole with a lid that discharges to a laundry cauldron or, alternatively, siphoning the metal in a continuous or semicontinuous manner by means of the refractory tube inserted in the metal through the annular end opening of the furnace which is introduced into an adjacent vacuum vessel external to the furnace, from which the metal is removed by emptying or other additional processing. Slags can - * ^^ -, ^ -,, -, ^ »_. . • - > > • ^ »t > - - ^ - to be discharged by the overflow of the edge of an annular end opening, including the defoaming which is required or optionally assisted by the inclination of the furnace along its ends, through a small angle or, alternatively by a slag removal system, vacuum, such as that described in the US Patent No. 5,305,990 of the same inventor. The process and apparatus is applicable to melt the various metals, for example, the ferrous metals comprising iron and steel slag, the raw smelting, the DRI microspheres, and also various virgin or recycled forms of non-ferrous metals such such as copper, aluminum, lead, zinc, chromium, nickel, tin and manganese. The mixtures of the metals and the metal oxides can be processed and they are adaptable to the acidic or basic slag and to the refractory practice. They adapt to a wide range of sizes of the material of the load, ranging from the fine granular particles loaded by the pneumatic injection, to the pieces of the size of the conveyor device of the metals in large recycled pieces. This facilitates continuous merging while the options of the download product are retained either continuously, intermittently or in batches. It also facilitates the transfer speeds of the - * - * M-- * • - "-i. *» * - i ^^^^^ a. high heat from beginning to end of the reaction zones of the process and avoids localized superheating or subcooling, as well as providing a good interaction of the metal-slag towards the composition that approximates the chemical equilibrium to obtain high yields of the product and a chemical composition consistent. The invention therefore represents a fast, clean, silent, thermally efficient and versatile technology for the metals fusion requirement. Various other objects, features and advantages of the process and apparatus of this invention will become apparent from the following detailed description and claims, and from reference to the appended drawings, in which: Figure 1 is a diagrammatic side view , partially in section, illustrating the typical characteristics of the process and apparatus of this invention; Figure 2 is a sectional view along the plane 2-2 of Figure 1; Figure 3 is a graph showing the exemplary transverse cycles for a case in which the loading materials are introduced by a combination of an oscillating conveyor apparatus and the injection lance of the solids; . '^. ^ .. I tt? - "- A. ^ - Figure 4 presents illustrative diagrams of the generally exemplary longitudinal distribution of the loading material input and other process inputs for the three exemplary cases; 5 Figure 5 presents diagrams of two other exemplary cases; Figure 6 is an illustration of the partial sectional side view of an oxygen lancet injection nozzle of the adapted gas stream 10 for distributing the oxygen for later consumption through the gas stream; Figure 7 illustrates an alternative embodiment of a nozzle as in Figure 8; Figure 8 is a diagrammatic side view, partially in section, illustrating the additional and alternative features of the process and apparatus of this invention; Figure 9 is a sectional view along plane 9-9 of Figure 8; Figure 10 is a sectional view along the plane 10-10 of Figure 9, with the portion of the plane below the axis of the central furnace being seen rotated approximately 45 degrees when the entrances in the submerged channel 65 coincide with the slag layer; Y -M-Éi-Í «M-Mii-Í-Íllb. F ~ ÍF1 ......... Sua ^ ..- & Figure 11 is a diagramatic side view, partially in section, illustrating the recirculation of the gas discharge to the hot gas stream comprising a part of the heat requirements of the process.

Detailed description of the invention Referring to Figure 1, the elongated rotary furnace 1 with the refractory lining 6 and incorporating the annular end openings 4, 5, is supported horizontally or with a slight inclination within the running rings 2 which are carried by, and rotated on, the rollers or cylinders 3 in a known manner. A partially molten metal bath 7 is maintained in a reaction zone 8 of the gas-solid-liquid and also a liquid metal bath 9 in a reaction zone 10 of the gas-liquid in the illustrated embodiment, with the baths carrying a floating layer of the slag 11. The furnace is heated by the burner 12 with the products of the combustion of the fuel for burning 13 and the oxygen and / or air 14 forming the hot gas stream 15 which passes countercurrent with respect to the movement of the general charge exiting through the general end opening 4 towards the conditioning chamber 16 that is introduced to the exhaust conduit 42 that precedes a gas cleaning and exhaust system to the atmosphere. The liquid metal of the process product can be discharged by periodically interrupting the derivation by turning the furnace through the hole with lid 17 in the cauldron 18 or the like or, alternatively, by siphoning during rotation by means of the refractory siphon tube 19 to an adjacent vacuum vessel 20. This vessel can optionally be heated, equipped for injection of gas, alloy and addition of flux 21 and discharge regulated by means of the sliding gate 22 according to the techniques of vacuum metallurgy and in the casting cauldron. Large and irregularly shaped loading materials such as recycled slag metals or reduced metal oxides in the form of bricks are introduced by transportation along the oscillating conveyor apparatus 24 which is placed on cantilevered beam through the end opening 4 and along the reaction zone of the gas-solid-liquid, causing them to fall down from the discharge edge 25 of the conveyor apparatus to the partially fused metal bath 7. The feeding speed can be controlled by several means, such as a block of . JM.,. . Jfc-- heavy 58 as illustrated, which carries a lifting magnet 57 for ferrous metals, or by other means of loading known quantities at controlled intervals. Several types of poidometers also apply to the 5 non-magnetic materials for loading the conveyor 24, particularly for the fluxes and reagents of the additive. A preferred embodiment of the conveyor apparatus 24 is of a horizontally oscillating type in which the driving means 26 of the oscillator oscillatingly moves the supporting plate 27 of the conveyor apparatus back and forth in short travels relative to the base 28 at a high frequency and a controlled cycle, in accordance with the practice known in the art of transportation. The cantilevered beam portion of the carrier plate of the conveyor is double-walled and is deflected by applying internally forced cooling water. The conveyor apparatus 24 is also mounted on the rollers 29 running on or the treads 30 which are substantially parallel to the axis of the furnace 6. Through the path of a cylinder 31 moving through the hydraulic conveyor apparatus, or equivalent, the position of the entrance of the loading material 32 is distributed < * > *** - - • ^ gsg ^ á ^ e ^ í * longitudinally along the transverse extension 33 of the reaction zone 8 of the gas-solid-liquid. Smaller-sized materials consistently smaller than about 3 cm are preferably introduced by dragging them into a carrier gas and transporting them pneumatically through an injection lancet of the solids 34 which injects the loading materials downwardly from the nozzle 35. the lancet towards the bath 7 at a speed sufficient to perform the submergence in the bath of metal and slags. In the illustrated embodiment, the lancet 34 is secured to a carriage 36 which travels on the rollers 37 running on the tread 38 which is also substantially parallel to the axis of the furnace 6. By means of the stroke of a driving cylinder 39 which moves through the hydraulic lancet, the position of the entrance of the loading material 40 is distributed longitudinally along the transverse extension 41 of the reaction zone 8 of the gas-solid-liquid. The lancet 34 is usually cooled with water, but may also comprise heat-resistant materials, such as alloys particularly suitable for a low melting point, such as those of aluminum or lead, or may even include materials of the consumable type, as know in the techniques of injection lancets. The front support • s * & * • - "" • ** •• - «-i ^ -JU-M-iil-iH-MláÍÉ 87 includes a pivot 88 around which the inclination of the lancet 34 is adjustable by the cylinder 89 carried on the rear support 90, making it possible to adjust the height of the nozzle 35 relative to the slag and the bath, which includes submerging the nozzle in the slags, or slag and bath, as may be preferred for certain process conditions. , such as the practice of foaming slag. The supports 87, 90 can each be carried on an A-frame or fixed arm, or alternatively, related to a common carriage frame, which can also be equipped to travel on wheels or treads, adapted for providing the longitudinal movement of the complete assembly in and out of the end opening 4 of the furnace. The zone 8 is also heated preferably directly by a burner 44, illustrated in Figure 2 as juxtaposed to the injection lancet of the solids 34, which can also be mounted for the adjustable longitudinal positioning. The supplementary oxygen for subsequent combustion can be introduced by means of the burners 44, or also by means of a separate afterburning lancet, optionally also adjustably placed. Since the hot gases within the outlet duct 43 are close to the atmospheric pressure, the dynamic sealing means such as the gas curtains are suitable for sealing the openings of the conveyor apparatus, the lancet and the burner duct, thus as the interface with the end opening 4. In the illustrated embodiment, the liquid metal is passed from the reaction zone 8 of the gas-solid-liquid, allowing it to flow out through the restricted passageway made by the annular refractory dam 23 to the reaction zone 10 of the gas-liquid. The dam 23 also serves to clog the unmelted parts of the charge materials and the increased flow velocity over the channel constrained by the dam 23 also substantially prevents any reverse flow of the metal from the zone 10 back into the zone 8. In cases of processing where strict temperature control, refining time to obtain chemical equilibrium within the bath and slag, are not necessary and / or processing in a supplementary vessel is necessary in some way, the oven 6 could be substantially shortened by eliminating the zone 10 and the intermediate dike 23, keeping a partially fused bath extending from the annular restricted opening 4 to the opening 5, discharging the metal and the ^^^^ _ ^ y ^ fe slag directly from the gas-solid-liquid reaction zone 8. The slags 11 can be removed by foaming or overflowing above the edge of the restricted opening 5, or even through the opening 4 in the case where it is beneficial-that the slags flow in countercurrent with respect to the metal for the process. The longitudinal inclination of the furnace 6 through the small vertical angles is an optional feature which is useful for discharge at the edge of the slag. The removal of the slag under vacuum as per the removal system described in U.S. Pat. No. 5,305,990 of the same inventor, can also be applied. With reference to Figure 3 together with Figure 1, the exemplary transverse cycles in which the fillers are introduced by the combination of an oscillating conveyor apparatus and a lancet for injection of the solids are illustrated. The discharge edge 25 of the conveyor apparatus is traversed forward at a speed of 0.3048 m / sec (1 ft / sec) until it reaches LCmax, where it inverts and returns to LCmin at 0.9144 m / sec. (3 feet / sec.), When the cycle is repeated. During the same time interval, nozzle 35 of the lancet traverses forward to LLmax at a speed of 1.22 m / sec. (4 ft / sec.), It is reversed and ,. ,, - .. * .. -, -r ,,. - .- ......, ^. t t.L¿U -A »returns to LLmin at 0.40 m / sec. (1.33 feet / sec.). In this example, the lancet and the conveying device travel directionally at the same time, but at different speeds on different stretches. These sections are also overlapped, to include a common traversed section for the entrance of the loading materials from the conveyor device and the lancet towards the bath. This example of the cycle employs a relative increase of the speed in the forward direction to reduce the transient effects of the "double dosage" near the reversal points of the route. A wide range of variations of the transverse cycle is available, such as the concentration of the feed input along the areas selected by the acceleration and deceleration of the path, the gradual speed changes, or the feeding during the travel in a only direction, interrupting the feeding during the trip in the other direction. Although the melting time in the liquid metal and the slags is very short for the individual particles or mipheres injected by the lancet, for example, less than one minute for the DRI mipheres and 10 seconds for the fine materials, the heat thus absorbed when the jet of solid charge materials is focused in one location can rapidly reduce the temperature of the liquid below the melting point, creating a frozen islet of solid metal which interferes with the operation of the process. The s path lancet as a feature of this invention not only eliminates this problem, but also ensures the maintenance of the melting and reaction rates of the process, at any temperature of the metal and slag bath, average. In addition to the lancet 34 for injection of the solids, the reaction zone 8 of the gas-solid-liquid is typically heated by a burner (not shown) that supplies a concentrated heat for melting, and also utilizes a lancet that supplies post-combustion oxygen at a relatively low pressure, preferably as described in co-pending patent application No. 08 / 916,395 by the same inventor (illustrated in Figures 2, 8 and 9). Given the typically numerous interaction process variables involved, the optimal insertion distance of these lancets in the gas-solid-liquid reaction zone is initially unknown and may vary during processing, and is therefore more appropriately established by trial and error during the operation. These lancets are therefore preferably mounted on a variablely placed carriage, similar to lancet 34, aligned in parallel as illustrated for example in the cross-section of Figure 3 showing a lancet 34 for injection of solids, burner 44 and lancet 45 of post-combustion oxygen carried in parallel above an oscillating conveyor apparatus 27. A lancet for injecting oxygen into the bath, of high speed, can also be introduced separately, or as a combination with the lancet 45 as a variation of the technology of the combined oxygen injection lancets, known. In addition to the variations in the crossing speed, the cross section and the longitudinal position of the section, the process and apparatus also provides the filling load of the injected solids along the different sections of the cross section. For example, additive carbon could be programmed for injection only during the last 50 percent of the forward lancet travel and the first 50 percent of the lancet travel backward, when it is regulated by the opening and closing of the lancet. a valve operated remotely on the supply line of the injected coal. This can eliminate the need for another separate carbon injection lancet while obtaining the desired distribution of carbon inlet in the bath during a high degree of afterburning.

The mode of operation and the configuration of the equipment can be varied according to the composition of the loading materials and the processing functions that are going to be carried out. This is illustrated by the diagram in Figures 4 and 5 that shows the exemplary distributions of the loading material input and other inputs in the fusion process. In case A, Figure 4, the ferrous fragments recycled in the company of the fluxes and the additive reagents are distributed along the first 50 percent of the reaction zone of the gas-liquid by the cyclic path of the oscillating load material fed to the conveyor, which is based on the rotation and inclination of the furnace to distribute the unmelted materials to the rest of the area. The carbon is shown as injected separately near the entrance to the zone, whereby the bath temperature is reduced and the heat transfer rate is increased, as described in U.S. Pat. No. 5,163,997 of the same inventor. Although a metal charge normally carries some surface oxides, the post-combustion oxygen that is injected separately would usually be guaranteed only in the case of oxygen injection in the bath, supplementary, as an optional practice in this case. Otherwise, the relatively small amounts of CO and H generated can be reacted with the oxygen of the supplementary burner. In case B, the DRI and iron carbide as the main fillers, are preferably fed by a lancet injection of the pneumatic solids, in the company of coal to reduce the residual iron oxides, with the cross section that is extends along a major portion of the gas-liquid reaction zone. Case C illustrates a combination of recycled fragments loaded by the conveyor apparatus with the granular materials pneumatically charged by the lancet for injection of the solids, including the overlapping sections of the travel or transverse travel. Case D, Figure 5 illustrates the addition of the oxygen injection of the supplementary bath, as well as the separate injection of oxygen for the post-combustion in the hot gas stream. The verification of the temperature and composition of the exhaust gas, as well as the composition of the product, the temperature and the speed of production during the operation, facilitates the selection of the most suitable entrances and their distribution. In any of the exemplary cases A and D, the materials of the filler may also include the metal oxides, for example, in the melting of ferrous materials, sawdust burrs, BOF slag, EAF powders of raw or preprocessed materials, in Additional carbon company as an addition reagent to reduce the oxides with respect to the metal. Exemplary Case E illustrates the merging of recycled aluminum and / or primary and similar aluminum ingots, which are usually of a size suitably loaded by an oscillating conveyor. The exposed surfaces of the aluminum, whether molten or non-molten, oxidize rapidly to an elevated temperature to form aluminum oxide slag or slag. Fluxing agents are required to retard oxidation and also to accelerate the inclusion, removal, recovery of metallic aluminum from debris or slags and clean the walls of the furnace from an accumulation of rust. The distribution of the entrances for the material, of load as in the example of the diagram to obtain an immersion essentially immediate, minimizes the oxidation of the aluminum without melting. Roof fluxes to prevent oxidation of molten aluminum by hot furnace gases typically comprise an almost eutectic KCI / NaCl mixture, also frequently including fluoride, chloride or carbonate compounds, additives. Several fluxes are also used as fluxes for foam formation, cleaning fluxes, and degassing fluxes in the aluminum melting technique, for example, MgCl2, various alkali chloride and fluoride salts, as well as oxygen-containing compounds for the exothermic reaction. It is known that these fluxes are usually more effective when they are supplied by flux injection, whereby they melt into small droplets within the bath offering a large specific surface area in contact with the molten material when they float on the surface. The distribution of the fluxes injected longitudinally along the continuous reaction zones, as in the diagram of this invention, substantially increases the proportion of the surfaces of the molten material placed directly in contact with the droplets of the flux. The reduction of magnesium content, commonly referred to as "demagnetization", is also a common requirement for secondary aluminum melting, usually carried out by the subsurface injection of chlorine-containing gases or a combination of fluxes and gases using lancets. simple gas injection, or including rotating nozzles and submerged porous plugs to obtain smaller bubbles which are more evenly and widely distributed in the molten material. The illustration of Case E shows how the functions of covering the slag and at least part of the degassing, cleaning and demagnetization functions can be carried out by distributing the injection of the solids and gases longitudinally along the continuous elongated reaction zones within the rotary kiln according to the invention. Figure 6 illustrates a preferred embodiment of a lancet nozzle 45 for releasing post-combustion oxygen to the hot gaseous stream 15. Oxygen is introduced via annulus 46 between the cylindrical external pipe 47 cooled with water and the cooled inner pipe 48 with water carrying a control disc 49 of the flow velocity, direction and distribution of the oxygen jet. The opening 50 of the nozzle with annular grooves is thereby defined between the end of the outer pipe 47 and the rear surface of the disk 49, whereby the oxygen jet 51 extends radially outward in a continuous curtain of oxygen. which extends transversely through the axially flowing gas stream. The disk 49 is preferably cooled with water, such as by the cooling water supplied by the internal water pipe 52 and returned by the annulus 53 of the internal pipe. The opening 50 can be shaped to improve the effectiveness of mixing with the gas stream to increase the reaction with fuels. For example, in the illustration, the opening 50 of the groove is angled upwards at approximately 30 ° with respect to the perpendicular, emitting a cone-shaped curtain radially outwardly, which is also of countercurrent flow with respect to the flow 15 of the gas stream, general. Also, the opening sector 50 which directs the oxygen jet 51 downwards towards the bath 7, becomes wider than the sector directing the jet upwards, for which a higher volume of oxygen is supplied to intercept directly the CO that develops from the surface of the bathroom. The width of the opening 50 and therefore the flow velocity of the oxygen at a selected pressure and velocity can be varied by adjusting the axial location of the pipe 48 by the axial sliding of the locating guide 54 of the internal pipe with respect to different locations within the outer pipe 47, for example, by applying different thicknesses of the spacer washers against a protrusion of the inlet end of the inner pipe 48. Figure 7 illustrates a variation of the nozzle embodiment of the pipe. lancet injection for the oxygen of the gas stream, in which a similarly mounted disk acts only as a baffle disk 55, adapted to deflect the oxygen jet 56 outward, which projects an annular oxygen curtain i-UL-h-f-H-ß-l-through the cross section of the gas stream of the furnace. Such oxygen injection of the gas stream provides the post-combustion oxygen which intersects the surface of the bath transversely with respect to the direction of metal flow, as well as the cross section of the full gas stream. The hot reacted gas mixture then flows over a significant distance simultaneously in contact and heating the partially fused bath and the furnace walls which, in turn, continuously agitates the bath and passes this heat from the wall from the afterburning into the bathroom when it rotates under it. The invention thus provides the clear advantage of increasing the PCD and the HTE over the processes of the prior art, for example, the process technologies of the oxygen converter and the electric arc furnace. Several features previously described with reference to Figure 1 are repeated in Figure 8, which also illustrates several additional or alternative optional features. To facilitate the foaming of the slags and the discharge on the edge of any end opening 4 or 5, such as in the slag bag 60, as well as to facilitate general access to the interior of the oven 1, it can be incunable longitudinally around of an oscillating support 61, such as by a hydraulic cylinder 62, the linear actuator, or the like. Alternatively, the support 61 can be placed directly under any set of the rollers 3, with the actuator 62 supporting the other set. Some processing requirements favor the use of a slag in zone 10 that has a different thickness of the layer and composition than the slags in zone 8. The transfer of slag between zones 8 and 10 can be restricted by the crest of an annular dam 63 sized to project above the highest level of the slag surface. One or more channels 65 through the dam 63 can allow substantially free passage of the liquid metal from the inlet opening 81 of the dike channel to the outlet opening 82 of the dike channel, while restricting passage of the channels. slag. With reference to Figures 9 and 10, to prevent substantial transfer of the slags through (del) of the channels (s) 65 the openings 81, 82 can pass through the slag layer, during rotation of the furnace 1 , the channel 65 can be tilted upwards in the generally radial direction towards the axis of the rotation furnace from the openings 81, 82 to an inner ridge 85 of the channel (not illustrated in Figures 8, 11). In both When the positions during each revolution of the furnace that the openings 81, 82 pass through the slag layer, it is observed that the inversion 86 of the inner ridge of the channel must be higher than the upper portions 83 and 84 of the channel. the openings 81 and 82 respectively, preferably at a distance at least equal to the maximum thickness of the slag layer, as illustrated, the investment 86 whereby it acts as a barrier adapted to limit the exchange of the slags between the zones 8 and 10 in any direction during the operation. Fluxes, alloys and gases, such as those required for the adjustment and refining of the metal composition in zone 10, can also be injected using a lancet assembly 66 that is longitudinally crossed, which is essentially analogous to the lancet. 34. A coherent jet lancet for the injection of oxygen or other treatment gas, which is known to maintain a narrow gas stream at a high velocity over distances of 2 meters or more from the nozzle, can also be employed to increase the longitudinal coverage using a less extensive mechanical assembly for handling the lancet. Optional after-treatment processing steps can be included, since the objects include the production of a wide range of products that have a composition and controlled and specific properties. For example, the lower portion of the liquid metal column 68 having its upper surface 69 at a level above the bath 9 governed by the regulated vacuum pressure, maintained within the container 20, may be extended laterally to include an after-treatment pool. metallurgical 70 confined within an enclosure 71 of the side channel through which the metal flows preceding the discharge, having a surface of the pool 72 maintained at a greater pressure and a lower elevation than the surface 69. When in or near atmospheric pressure, surface 72 is also typically approximated to the level of the metal surface and slag 9, 11, as governed by the principles of Bernoulli's theorem. The metal can be discharged through a submerged nozzle 73. The control of the adjustable flow rate of a slider gate 74 of nozzle throttling, a dosing screw or a stop rod or retainer, then also controls the discharge flow. of the furnace through the siphon tube 19, at the same average speed as the discharge of the metal through the nozzle. Alternatively, the metal can be discharged by sliding from the pool 70 by overflow, in which case the discharge speed of the furnace requires control by other means, such as varying the vacuum pressure within the enclosure 20 or the inclination control of the furnace. post-treatment assembly. Also, the high vacuum pressures inside the enclosure 20 can remove substantial amounts of the gases dissolved in the metal prior to passage to the pool 70. In another variation, the siphon tube 19 can be discharged directly into the evacuated space 76 on the upper surface 69, obtaining a degree of degassing by spraying, but which also requires the direct regulation of the discharge flow velocity through the tube 19 by varying a vacuum pressure, or by other means. The sealing of the channel enclosure 71 and the closing of the throttle valve 74 and other outlet openings facilitates the initial evacuation of the container 20 to begin the flow of the metal. The container 20 can also be equipped with an inlet valve 67 which is kept closed during the evacuation, then opened to allow the flow to start. As an example (see Figure 8), aluminum processing commonly involves employing a mixture of inert gases and reactive gases for the degassing and demagnetization of molten metal following melting, which can be introduced by means of porous plugs or of a treatment chamber ^^^^^^^^^^^^^^^ of the gases 75 through the porous refractory material 76 when the metal travels through a series of screens 77 to increase the effective length of the after-treatment channel. The metal then passes up through the filter 78 for removal of the non-metallic substances and the like, then discharges downward through a nozzle 73 having a discharge velocity controlled by a screw for flow control, the stop rod or stopper or slide gate valve 74 for throttling. The metal that is processed can be heated, such as by electric resistance heating element 79 and the source 72 protected from oxidation by introducing an additional gaseous layer 80, also providing the evacuation of these gases in the gas treatment and handling system. escape Many variations of this metal treatment system are feasible, for example, rotating gas diffusers to divide the treatment gases injected into small bubbles that could be used in addition to, or instead of, the gases introduced through the material refractory porous 76. Various treatment gases may be used, for example, aluminum treatment gases are typically mixtures of inert nitrogen and argon with reactive chlorine and fluorine compounds, in accordance with filtration and degassing refining systems that precede the pouring of molten material. The very high temperatures characteristic of the oxy-fuel flames can be excessive when the metals that melt have relatively low melting points, such as aluminum and lead. The recirculation of the gas discharge, as illustrated in Figure 11, can mitigate this problem. A substantial and controlled portion of the gaseous discharges can be recycled through the recirculation conduit 92 of the gas discharge, usually coated with refractory material, by a recirculation blower 93 of the gas discharge, usually equipped with a cooled impeller. Water. The blower 93 can be operated at a controlled variable speed, or the flow volume can also be controlled by a separator or damper 94, also cooled with water. The exhaust gases 99 comprising the non-recirculated gaseous discharge pass directly through the exhaust conduit 95, also preferably equipped with a damper or separator 96. The conduit 92 can exit directly towards the furnace, because it is also equipped with a gas burner. separated oxy-fuel or, as illustrated, in a pre-combustion chamber 97 which is also burned or ignited 5 by an oxy-fuel burner 98, with the products of ^^^^^ combustion, in turn, which are discharged to the reaction zones of the furnace and forming the hot gaseous stream. The overall result is to generally reduce the temperature of the exhaust gas and the average furnace, to improve the thermal efficiency of the process, also avoiding localized overheating and the formation of unnecessary nitrogen oxide. Exhaust gases 99 can also be used to preheat the cargo materials, fuel or oxygen by recovery, further improving the heating economy of the process.

It is noted that in relation to this date the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following ^^ -É - É-Í-l-U-H

Claims (35)

1. A process for the continuous melting of a load of solid metallic materials, comprising metals selected from the group consisting of recycled fragments of iron and steel, of crude smelting, of copper, of aluminum, of lead, of zinc, of chromium, of nickel, tin, manganese, and directly reduced iron, which have been previously produced by a separate processing facility that carries out the direct reduction in solid state of the iron oxides and which have been discharged and cooled at ambient temperature and exposed to the external atmosphere for transport and storage, in an elongated rotary furnace having a horizontal longitudinal arrangement and extreme annular openings which maintain a bath partially molten of the metal carrying a floating layer of slag in an area of reaction of the gas-solid-liquid, elongated, with a hot gaseous current that passes over the metal and the slag inside The furnace, characterized in that it comprises: transporting the materials of the metallic charge through at least one of the extreme openings towards the hot gaseous stream and along the reaction zone of the gas-solid-liquid; . * «. J i »aCaM project downwards the materials of the metal charge, towards the bathroom; traversing or crossing the projection location downwards successively backwards and forwards, along a longitudinal cross section of the reaction zone of the gas-solid-liquid and whereby the position of the entrance of the material is distributed. the loading of the materials of the load, towards the bath, longitudinally along the reaction zone of the gas-solid-liquid; and allowing the liquid metal to flow out of the reaction zone of the solid-liquid-gas to provide the bath filling by transport and downward projection of the metallic charge materials.

2. A process according to claim 1, characterized in that the transportation includes the entrainment and propulsion by the pressurized carrier gases in at least one portion comprising a lancet feeding portion of the solid charge materials through a lancet. injection of the longitudinally cantilevered beam solids into the hot gaseous stream; the downward projection comprises drawing a jet of charge materials and carrier gases from a lancet nozzle into the bath; and the crossing or crossing passage comprises moving the lancet successively back and forth longitudinally, distributing the position of the nozzle and therefore the position of the entrance of the loading material along the transverse section.

3. A process according to claim 1, characterized in that the transport includes the propulsion of at least one portion comprising a supply portion of the conveyor of the solid load materials by the longitudinal oscillation of an oscillating conveyor device placed on a cantilever beam. longitudinal way inside the hot gas stream; the downward projection comprises dropping the loading materials from a discharge edge of the conveyor apparatus into the bath; and the crossing step comprises moving the conveyor apparatus successively back and forth by longitudinally distributing the position of the discharge edge and thereby the position of the material input of the load along the transverse section.

4. A process according to claim 1, characterized in that the transportation includes the propulsion of a portion of the solid load materials by the longitudinal oscillation of an oscillating conveyor device positioned in a cantilevered beam longitudinally within the hot gas stream; the downward projection comprises dropping the portion of the loading materials from a discharge edge of the conveyor to the bath; the crossing step comprises moving the conveyor apparatus successively back and forth longitudinally distributing the position of the discharge edge and thereby the position of the input of the loading material of said portion of the loading materials along a fed portion by the conveyor apparatus of said transverse section, and also includes dragging and propelling by the pressurized carrier gases another portion of the solid charge materials through the injection lancet of the solids placed in cantilevered beam longitudinally within the hot gas stream; the downward projection comprises drawing a jet from the other portion of the charge materials and the carrier gases from a lancet nozzle into the bath; Y t ^ igj ^ mj the crossing step comprises moving the lancet successively back and forth longitudinally, distributing the position of the nozzle and therefore the position of the input of the loading material of the other portion of the loading materials as length of a portion fed by the lancet of the transverse section.

5. A process according to claim 4, characterized in that the portion fed with the lancet is superimposed on the portion fed with the conveyor apparatus of the transverse section through a common transverse extension portion of the longitudinal cross section, including the coordination of the intervals time of the travel cycle and the positions of the lancet nozzle relative to the discharge edge, whereby crossing between the loading materials coming out of the lancet nozzle and those falling from the edge of the lancet is avoided. discharge of the conveyor device, through the common transverse section during the crossing step.

6. A process according to claims 2, 4 or 5, characterized in that it includes the distribution of the feeding speed of the fillers leaving the jet unevenly along the portion fed with the lancet of the transverse section, making varying the flow velocity of the entrained filler materials during lancet travel or movement, while maintaining an average, substantially constant, overall feed rate of the material of the load across the total length of the portion fed with the lancet.

7. A process according to claims 2, 4 or 5, characterized in that it includes distributing the feed speed of the materials of the load that come out from the jet in an unequal manner. 15 along the portion fed with the lancet of the transverse section, varying the speed of movement or travel of the lancet, while maintaining an average, substantially constant, total feed rate of the loading material through the length 20 total of the portion fed with the lancet.

8. A process according to claim 1, characterized in that the metallic materials contain metal oxides and the reagents of 25 additive include a carbonaceous material, including ^^^ ¡^^^^^. effect the reduction of metal oxides in the bath and slag by the carbon contained in the carbonaceous material, whereby the liquid metal is formed in the reaction zone of the gas-solid-liquid and release the carbon monoxide in the stream hot soda; and injecting the oxygen into the hot gaseous stream by post-combustion of a major portion of the carbon monoxide to form the carbon dioxide prior to the exit of the hot gaseous stream from said gas-solid-liquid reaction zone.

9. A process according to claims 1, 2, 3, 4, 7 or 8, characterized in that it includes maintaining a reaction zone of the gas-liquid adjacent to the reaction zone of the gas-solid-liquid; maintaining a general movement of the materials within the metallic bath partially melted in a direction towards the reaction zone of the gas-liquid allowing the liquid metal to flow towards the reaction zone of the gas-liquid; heating the reaction zone of the gas-liquid by combustion of fuel and oxygen to regulate the temperature of the liquid metal and also form the hot gas stream; effecting or carrying out the flow of the hot gas stream in countercurrent with respect to the general movement of the materials for exhaust through the annular end opening adjacent to the reaction zone of the gas-solid-liquid; and discharging the hot liquid metal from the reaction zone of the gas-liquid.

10. A process according to claims 1, 2, 3, 4, 7, or 8, characterized in that the total distance through the longitudinal cross section comprises more than 50 percent of the length of the reaction zone of the gas-solid- liquid.

11. A process according to claims 1, 2, 3, 4, 7 or 8, characterized in that it includes discharging the liquid metal by siphoning through a suction tube into a vacuum chamber containing a column of liquid metal under a pressure of controlled vacuum; allowing the liquid metal to flow from the vacuum chamber into an after-treatment pool within an enclosure of the side channel under a higher pressure than the controlled vacuum pressure; introduce metallurgical treatment gases into the pool comprising the metal; and discharge the liquid metal from the pool.

12. A process according to claim 11, characterized in that it includes maintaining a continuous flow of the liquid metal through the pool and discharging the metal through a submerged nozzle, which also includes regulating the velocity of the discharge flow through the the nozzle by the throttling of the nozzle opening, whereby also the flow rate of the metal, average, is controlled through the siphon tube.

13. A process according to claim 11 or claim 12, characterized in that the pressure higher than the controlled vacuum pressure comprises a substantially atmospheric pressure.

14. A process according to claims 11, 12 or 13, characterized in that it includes the step of removing by filtration the inclusions and non-metallic impurities in the metal flowing through the pool by the passage of the metal through a porous filter prior to download.

15. A process according to claims 1, 2, 3, 4, 7 or 8, characterized in that it includes maintaining a gas-liquid reaction zone adjacent to the reaction zone of the gas-solid-liquid; heating the reaction zone of the gas-liquid by combustion of the fuel and oxygen to regulate the temperature of the liquid metal and also to form the hot gas stream; effecting the general flow of the hot gas stream in countercurrent with the general movement of the materials through the exhaust through the annular end opening adjacent to the reaction zone of the gas-solid-liquid; obstruct the flow of the slags between the reaction zone of the gas-solid-liquid and the gas-liquid by maintaining the internal perimeter of an annular dam above the upper surface of the slags; allowing the liquid metal to flow into the reaction zone of the gas-liquid by means of at least one channel through the dam which is submerged within the bath for a portion of each revolution; discharge slag when required through the annular end opening adjacent to the gas-solid-liquid reaction zone; and discharging the hot liquid metal from the reaction zone of the gas-liquid.

16. A process according to claim 15, characterized in that it also includes introducing materials selected from the group comprising the fluxes and addition reagents in the reaction zone of the gas-liquid, forming a slag layer within the reaction zone of the gas-liquid that has a different composition than the slags contained in the reaction zone of the gas-solid-liquid.

17. A process according to claims 1, 2, 3, 4, 7, 8, 10, 16 or 17, characterized in that it includes recycling a portion of the hot furnace gases released from an annular end opening of the furnace to the other extreme opening ring for mixing with, and comprising a portion, of the hot gas stream inside the furnace.

18. An apparatus for carrying out the continuous melting process of the solid metallic charge materials comprising the metals selected from the group consisting of recycled iron fragments and steel, the raw cast material, copper, aluminum, lead, zinc , chromium, nickel, tin, manganese, and reduced iron directly which has been previously produced by a separate processing facility that conducts direct reduction in the solid state of the iron oxides and which have been discharged and cooled to the environmental temperature and exposed to the external atmosphere during transportation and storage, in an elongated rotary furnace having a horizontal longitudinal arrangement and extreme annular openings, maintaining a reaction zone of the gas-solid-liquid inside the furnace, adapted to contain a bath partially molten of the metal carrying a floating slag layer heated by a hot gaseous stream passing over the bath, the apparatus is characterized by the combination of the following: means for transporting the materials of the metal charge through at least one of the extreme openings towards the hot gas stream and along the zone of reaction of the gas-solid-liquid and projecting downward the materials of the load towards the bath; means for traversing the means for transport and projecting downwards the materials of the metal charge successively backwards and forwards, adapted to longitudinally distribute the position of the entrance of the material of the load along a longitudinal cross section of the zone Reaction of the gas-solid-liquid; and means for exiting the liquid metal by allowing the liquid metal to flow out of the reaction zone of the solid-liquid gas, adapted to provide the bath filling by the solid, metallic charge materials.

19. An apparatus according to claim 18, characterized in that the means for the transport and the downward projection of the materials of the load include a lancet for injecting the solids, pneumatic, placed on a cantilevered beam longitudinally inside the hot gas stream. along the reaction zone of the solid-liquid gas with a downstream lancet outlet nozzle, adapted for injection of the solid charge materials into the bath of the partially molten metal; and means for carrying out the crossing step comprising an inverting or reversible lancet driving means, adapted to move the lancet successively back and forth along the transverse section.

20. An apparatus according to claim 18, characterized in that the means of transport and downward projection of the materials of the load include an oscillating conveyor device placed on cantilevered beam within the hot gas stream along the zone of the reaction of the solid-liquid gas with a discharge edge of the conveyor apparatus adapted to bring the solids charging materials downward, towards the partially molten metal bath; and the means for crossing comprises an inverting or reversible drive means adapted to move the oscillating conveyor apparatus successively back and forth along the transverse section.

21. An apparatus according to claim 18, characterized in that the means for the transport and the downward projection of the materials of the load include a lancet for injecting the solids, pneumatic, placed on a cantilevered beam longitudinally inside the hot gas stream. along the reaction zone of the solid-liquid gas with a lancet outlet nozzle directed downwards, adapted for the injection of the solid charge materials in the partially molten metal bath; the means for crossing comprises an inverter or reversible lancet means adapted to move the lancet successively back and forth along a portion fed with the lancet of the transverse section; it also includes a conveyor apparatus longitudinally cantilevered into the hot gaseous stream along the gas-solid-liquid reaction zone with a discharge edge of the conveyor adapted to bring down the materials of the solid charge down into the bath of the partially molten metal, and the crossing passage comprises a drive means of the reversing or reversing conveyor apparatus adapted to move the oscillating conveyor apparatus successively back and forth along a portion fed with a conveyor apparatus of the transversal section.

22. An apparatus according to claim 21, characterized in that the portion fed with the lancet is superposed on the portion fed with the conveyor apparatus of the transverse section through a common transverse extension portion of the longitudinal cross section, including adapted transverse coordination means. to control the time intervals of the travel cycle and the position of the lancet exit nozzle relative to the discharge edge during the crossing passage, whereby crossing between the loading materials leaving the nozzle is avoided of the lancet and those that leave the discharge edge through the common transverse section during the crossing step.

23. An apparatus according to claims 18, 19, 20 or 21, characterized in that it includes means for maintaining a reaction zone of the gas-liquid carrying substantially only a hot liquid metal and the slags adjacent to the gas reaction zone. solid-liquid inside the oven; means for the introduction of fuel and oxygen, adapted to heat and regulate the temperature of the metal in the reaction zone of the gas-liquid by combustion and the formation of the hot gas stream; means for effecting or carrying out the general flow of the hot gaseous stream in countercurrent with respect to the general movement of the materials into and through the reaction zone of the solid-liquid-gas and discharging the hot gaseous stream through a adjacent annular end opening of said furnace, and means for discharging the hot liquid metal from the gas-liquid reaction zone.

24. An apparatus according to claim 18, characterized in that it also comprises: a vacuum vessel led adjacent to the annular end openings having a siphon tube with its outlet connected to the container and its inlet adapted for insertion through the extreme opening in the liquid metal inside the furnace; means for evacuating and maintaining a controlled vacuum pressure inside the container, which causes the liquid metal to flow through the suction tube adapted for the formation and maintenance of a liquid metal column within the container; an enclosure of the side channel communicating with the metal column adapted to transport a metal after-treatment pool that flows outwardly from the column under a higher pressure than the controlled vacuum pressure; and means for discharging the liquid metal from the after-treatment pool.

25. An apparatus according to claim 24, characterized in that it includes means for the after-treatment of the gas supply adapted to introduce the treatment gases into the metal flowing into the pool.

26. An apparatus according to claim 24, characterized in that the means for discharging the liquid metal from the after-treatment pool comprises a submerged nozzle equipped with a throttle valve for regulating the discharge velocity of the metal.

27. An apparatus according to claim 24, characterized in that the channel enclosure includes screens adapted to increase the total distance traveled by the liquid metal between the inlet from the column and the outlet of said discharge.

28. An apparatus according to claim 24, characterized in that the means for discharging the liquid metal from the after-treatment pool comprises an overflow edge from the channel enclosure, which also includes means for throttling the flow through the suction tube. .

29. An apparatus according to claims 24, 25, 26, 27 or 28, characterized in that the pressure higher than the controlled vacuum pressure comprises a substantially atmospheric pressure.

30. An apparatus according to claims 24, 25, 26, 27, 28 or 29, characterized in that it includes means for sealing the enclosure of the side channel adapted to exclude air access to the surface of the after treatment pool.

31. An apparatus according to claim 23, characterized in that it also includes an annular dam near the junction between the gas-solid-liquid and gas-liquid reaction zones which extend radially inwardly from the internal side walls of the container. rotary furnace up to a crest of the annular dam with an inversion at a level higher than the surface of the slag layer during the complete rotation of the furnace, whereby it is adapted to obstruct the longitudinal transfer of slags between the two zones .

32. An apparatus according to claim 31, characterized in that the dam includes at least one channel communicating longitudinally through the dike with an inlet opening of the dike channel outside the reaction zone of the gas-solid-liquid and in a exit opening of the channel of the dam within the zone of reaction of the gas-liquid, adapted to allow the exit of the liquid metal from the zone of the reaction of the gas-solid-liquid.

33. An apparatus according to claim 32, characterized in that the channel is inclined upwards in the generally radial direction towards the axis of rotation of the furnace, reaching a ridge within the channel where the inversion of the ridge is at a higher elevation that the elevation of the part When the top portion is passing through the slag layer, the ridge is therefore adapted to substantially block the transfer of the slag. 20 from the liquid-solid-liquid reaction zone within the reaction zone of the gas-liquid through the channel during operation.

34. An apparatus according to claim 33, characterized in that the crest is WMHii-l-ia-á-. -rit --- á-a-É-Mi-. intermediate between the inlet opening and the outlet opening, whereby it is adapted to block the transfer of the slags in any direction between the reaction zone of the gas-solid-liquid and the gas-liquid.

35. An apparatus according to claim 18, characterized in that it includes a gas recirculation duct adapted for transferring a portion of the hot furnace gases discharged from the annular end opening and reintroducing them in the furnace through the other end opening, whereby the portion of the exhaust gases is recycled for mixing therewith and comprises a portion of the hot gas stream and the discharge of only the remaining exhaust gases.