FI88177C - REFERENCE TO A REDUCTION OF A METALLOXIC MATERIAL - Google Patents

Description

88177 Method and apparatus for reducing metal oxide-containing material.

Metallic oxide dipotene materials in pelkistysmenetelmä ja laite.

The present invention relates to a process for preheating and pre-reducing metal oxide-containing material such as silk or ore concentrate, to prepare a pre-reduced product suitable for final reduction, wherein the metal oxide-containing material is fed into a flame chamber which is disposed in an above-mentioned step and is flammable in a flame chamber. , a rotary motion is imparted and guided down to the final reduction stage.

The present invention also relates to a device for preheating and pre-reducing metal oxide-containing material. : as such or ore concentrate, to produce a pre-reduced product suitable for: final reduction, comprising - a flame chamber whose outlet for molten and pre-reduced material if the lower part of the chamber is (directly) connected to a side reduction stage, - devices for feeding preheated metal oxide-containing material in the flame chamber and devices for imparting the metal oxide-containing material to a rotary movement in the flame chamber.

2 881V7

Methods have been previously proposed for direct reduction of metal oxide-containing material to molten metal e.g. processes in which the metal oxide in direct contact with the metal melt in a melt bath is reduced with carbon-dissolved material dissolved in the melt. The metal oxide is then fed into the melt bath together with koi or oil. The reaction in the melt

C + MeO = Me + CO

is endothermic and requires additional heat. The heat can e.g. is obtained by combustion of the CO gas formed at the reduction.

However, it is difficult to transfer the heat released during CO combustion sufficiently into the melt. Various methods have been proposed by which the heat could better be transferred to the melt and the metal oxide. It has among other things suggested that the reduction be carried out in a rotary reactor whereby the heat from the combustion transfers to the melt via the furnace liner. Such a procedure would place great demands on the furnace lining.

20

It has also been suggested that the heat demand during the reduction process be covered with electrical energy. According to that process, the combustion heat of the gases generated by the reduction is used to generate electrical energy, which is then wholly or partially utilized to heat the melt. Even if the entire heat content of the exhaust gas was utilized, the electrical energy generated from the exhaust gases would not suffice to cover both the energy demand in the reduction of the metal loxides and heat losses. Additional energy would be required. Additive fuels can be used to preheat and / or pre-reduce the metal oxide-containing material or to generate electrical energy to meet the heat demand in the reactor.

It is also known previously, e.g. by Swedish patent specification SE 419 129, to reduce, in whole or in part, finely divided iron oxide-containing material in a circulating fluidized bed, consisting of a two-part reactor in which an upper and a lower reaction room are connected to each other. Such is fed into the lower reaction chamber. In the upper reaction room, carbonaceous material is fed which partly provides the reducing gas required for the reduction and partly covers the heat demand in the reactor by partial combustion. Combustion air is fed into the upper reaction room. From the reactor separated and purified exhaust gases are recirculated to the lower reaction chamber and utilized partly for fluidization in the reactor and partly as reducing agents. The reduction occurs in the circulating fluidized bed at a temperature below the iron melting point. According to an example in the patent, the carbon powder supply was 700 kg / ton Fe.

The kinetics of the reduction reaction Fe2 O3 === FeO is disadvantageous at the low temperatures that may occur in fluidized bed reactors, e.g. of the type described above. At 800 ° C, reaction times of several minutes are allowed. tens of minutes, depending on the grain size and the desired degree of reduction. An increase in temperature level sufficiently high to provide an acceptable rate of reaction cannot occur in a circulating fluidized bed since the propensity for the particles in the bed to coincide simultaneously would increase.

Pre-reduction of metal oxide at 800 ° C in a fluidized bed reactor requires some reduction potential of: the reducing gas. This leads to equilibrium that: the gas will still have significant amounts of reducing components such as CO and H2 at the outlet. Through the etheric circle -. *. ·. 30 of the gas with e.g. However, CO 2 and H 2 O separation can make better use of the reducing components. Through . gasification of a portion of the carbonaceous reducing agent in the ... fluid bed could maintain a sufficient reduction potential * -] ', but without other simultaneous measures, the energy efficiency of this process deteriorates.

In addition, the Swedish patent specification SE 395 017 is known to pre-reduce metal oxide-containing material in a 4,8177 shaft in a molten state, ie at higher temperatures than described above. In the upper part of the shaft, where oxidizing atmosphere prevails, heat is generated by combustion of solid, liquid or gaseous fuels. The metal oxide-containing material is caused to fall heated down in the shaft and fall through contact with the generated hot gases. The material is partially pre-reduced by the combustion gases. However, the actual pre-reduction of the material occurs mainly first in the lower part 10 of the shaft with carbonaceous reducing agent introduced into the upper part of the shaft, cooks and falls down to the lower part of the shaft, where a reducing atmosphere is achieved. Part of the carbonaceous reducing agent introduced at the top of the shaft is also utilized for heat generation. The shaft must therefore be supplied with energy for heating, melting and reduction of metal oxide-containing material. The exhaust gases will therefore contain a large amount of energy. The problem in the process is to be able to utilize this amount of energy optimally.

In addition, where the rising exhaust gases from the shaft attract both droplets of molten metal oxide and solid particles of reducing agents, metal oxides and any other process additives, the cleaning of the exhaust becomes very problematic. The metal oxide particles may conveniently be separated from the exhaust gases only after the gas has been cooled to a temperature below which all molten particles have solidified and can no longer cause clogging of particulate separators and gas purifiers, preferably at temperatures below 1000 ° C. After cooling and separation, the particles can be re-introduced into the process, but require a new heating, leading to a degraded energy efficiency. Cooling the gases to below 1000 ° C, possibly in conjunction with heat recovery, also offers practical difficulties.

The present invention aims to provide an improvement of the pre-reduction processes described above.

35 5 88177

The present invention also intends to provide a process in which the energy content of the gases formed in the sub-processes is accommodated in the overall process to minimize the energy needed in the production of the molten metallic product.

The invention thus aims to achieve a process of improved energy economy and improved kinetics of the reduction.

The invention also relates to a process in which the melted and solid particles accompanying the exhaust gases from the pre-reduction stage in the flame chamber can easily be separated and re-introduced into the pre-reduction stage and thereby thereby reduce smaller quantities and at the same time cleaner exhaust gases.

By the present invention, a surprisingly simple way has been solved the problems with the reduction processes previously described, characterized in that - the metal oxide-containing material, prior to entering the flame chamber, is fed and preheated in a fluidized bed reactor connected to the flame chamber, whereby - from the flame chamber into the reactor's bottom: .V part for fluidization and preheating of the metal oxide-containing material in the reactor; • · · - preheated metal oxide-containing material is separated from the exhaust gases emitted from the reactor and separated - the metal-oxide-containing material is partly reacted to the reactor. in the flame chamber, and that ... - the preheated metal oxide-containing material fed into the flame chamber is at least partially melted and / or pre-reduced using hot reducing gases from the final reduction stage.

Pre-heating and pre-reduction of metal oxide-containing material can according to the present invention be carried out in a device characterized in that - a tiled chamber upper part connected with a fluidized bed, for preheating the metal oxide-containing material before entering the flame chamber, where - its lower part has an intake for hot exhaust gases from the flame chamber and in its upper part is connected to a particle separator for separating preheated metal oxide-containing material from the gases emitted from the reactor, and - the particle separator is connected to the reactor through a feed line. - an inlet connected to the lower part of the flame chamber for hot reducing gases from the final reduction stage.

According to the invention, the preheated metal oxide-containing material can be melted directly in the flame chamber by means of the heat content of the hot ascending gases from the final reduction stage, the metal oxide-containing material being advantageously fed into the lower part of the flame chamber. The metal oxide-containing material is fed so that as good as possible contact is made between the material and the rising gases whereby melting and pre-reduction of the material can take place in the lower part of the flame chamber. The rising gases pull the molten and pre-reduced material higher up into the flame chamber where the material is imparted in a rotary motion and thrown out onto the walls of the flame chamber. In the molten state, the pre-reduced material then flows down to the final reduction stage.

The preheated material can also be melted by heat from the combustion of one part or all of the reducing gases in the flame chamber itself. The combustion can take place in the upper or lower part of the combustion chamber depending on the input of the combustion maintenance agents. Air, oxygen-enriched air, oxygen or the like. can be used in combustion.

7 88177

The gases from the final reduction are advantageously fed up through the opening in the bottom of the flame chamber through which molten metal oxide-containing material flows down to the final reduction stage. However, in some applications, the gases can be fed through inlet ports in the sides of the flame chamber or upper part. Good contact between the gases and the preheated metal oxide-containing material should be ensured.

The reducing gases from the final reduction can be partially or completely burned in the flame chamber and utilized for bed melting and reduction of the preheated sieve without affecting the p4 pre-reduction process in the flame chamber, due to combustion and pre-reduction in different zones. This leads to maximum utilization of the reduction potential of the gases and to minimal reduction potential of the outgoing gases.

Depending on how much of the reducing gas consumed during combustion, other reducing agents can be added to cover the need for reducing agents in the pre-reduction of the metal oxide-containing material. According to one embodiment of the invention, carbonaceous material is used as reducing agent. The carbonaceous material is fed into the flame chamber, advantageously at the same time as the combustion-maintaining gas. The combustion maintenance gas burning combustion reduces gases and: ***: forms hot flames, zones with high combustion potential, preferably in the middle of the flame chamber. Volatile substances in coal 30 can also be combusted. Advantageously, the carbon residence time in the hot flame is so short that the carbon is not significantly burned. without coking alone. The metal oxide-containing material is fed so that it comes into contact with the hot flames and melts. The melt and the resulting coke are imparted in a rotating motion and thrown out toward the flame chamber wall.

: The coke particles help to form a reducing zone at the wall whereby the metal oxide in a substantially molten state is reduced. Thus, the gases at the flame chamber wall need not be in equilibrium with the gases in the middle of the flame chamber.

Where additional reducing agents, such as may be carbonaceous reducing material fed into the flame chamber, it should preferably have a particle size sufficient to cause the reducing agent not to be immediately combusted in the flame, but substantially coked. There, the carbon-containing carbon-containing agent in the heat will be poured out unburned onto the walls and mixed there as coke particles in the metal oxide melt. The presence of coke particles results in a high reduction potential of gas bubbles in the melt and in the gas layer of the melt, which results in the retention of a few millimeters of thick continuous continuous liquid layer of molten, pre-reduced metal oxide on the wall surface.

The flame chamber in the embodiment described above can conveniently be formed as a cyclone where solid and liquid particles are separated from the gases. The residence time of the gases in the flame chamber is on average several tenths of seconds. Despite the short residence time, the gases are able to emit heat and the particles are heated and melted, thanks to the intense turbulence in the cyclone. The turbulence enhances the heat transfer through radiation and convection to the suspended particles. The residence time of the molten metal oxide and the cured reducing agent moves for a number of seconds, calculated as the time the material settles on the walls.

For example, in a flame chamber with the upper diameter d1 = 2460 mm and the lower diameter d2 = 1920 mm and whose height h = 1700 mm is fed 7.5 t / h ironically. The temperature of the flame chamber is 1600 - 1700 ° C. In this way, a melted, pre-reduced layer on the wall of the flame chamber is raised. The residence time of the gases is about 0.2 seconds. In contrast, the melt, which flows down the wall, gives a residence time of approx. 10 seconds.

9 88177 The pre-reduction in the flame chamber takes place quickly because the metal-oxide-containing material thanks to the preheating, quickly attains a temperature which can be reduced to the reduction. Thus, the metal oxide-containing material already has a relatively high temperature at the feed-in to the pre-reduction stage. The material is preheated to a temperature which, however, should not exceed the material's cladding temperature to avoid agglomeration in the fluidized bed. A temperature between 600 - 950 ° C has usually been found suitable. Particularly the metal oxide-containing material is fed in close contact with hot flames in the flame chamber or with hot reducing gases, the material will quickly be heated to a temperature advantageous to the pre-reduction, whereby the pre-reduction takes place very quickly. For example, the reaction Fe 2 O 3 == Fe 3 O 4 == FeO 15 occurs almost spontaneously at temperatures above 1200 ° C - 1300 ° C.

One of the most important advantages of the process according to the invention lies in improved energy economy. The need for externally supplied energy for pre-reduction and melting is minimized as the metal oxides are fed preheated to the flame chamber. Also, the energy demand at the final reduction itself is minimized by introducing the metal oxides pre-reduced and essentially melted state into the final reduction.

The energy content of the gases formed is utilized to the maximum. Firstly, the heat content of the gases is optimally utilized at: the preheating of the fluidized bed, and secondly, the preheating can be done with s.g. s. exhausted exhaust gases. In the prior art fluidized bed processor, preheating has preferably occurred with reducing gases, the exhaust gases from the processes having still been significant. chemical energy content, which could not be utilized optimally.

A pre-reduction with solid phase metal oxide as it is carried out e.g. in a fluidized bed, on the other hand, would require a higher amount of CO in the reducing gases. This would lead to increased need for reducing gases from the final reduction stage and, consequently, increased carbonate thread at the final reduction stage.

Preduction in melt significantly reduces the need for reducing agents. On the other hand, if the pre-reduction were to take place in a fluidized bed, the need for koi would be considerably greater in order to obtain sufficient reduction potential in the gas. X pre-reduction at 1500 ° C in the molten state, the exhaust gases from the pre-reduction will contain only about 5% CO, while at pre-reduction in 800 ° C solid phase e.g. in fluidized bed would still contain about 30% CO.

Of course, final reduction of fully molten FeO to metal requires less energy than final reduction of solid FeO. The reduction of FeO in the final reduction step occurs with C via CO, where the formed CO 2 is immediately thanks to the carbon present being re-formed to CO. Thus, from the reaction zone, mainly CO. If oxygen or air is supplied to the bath itself, combustion will only take place at CO. However, final combustion of the formed CO can occur above the bath surface. A combustion above the bath surface adds additional heat to the bath. The gas formed above the bath can contain up to 60% CO 2 without detrimental effect on the final reduction. The gas produced still contains enough CO to cover the reduction potential and heat demand in the flame chamber. The heat requirement is, thanks to the preheating of the fluidized bed less than if the unheated sieve would be measured in the pre-reduction stage.

The process according to the invention has a much lower energy demand, carbonate thread, than a process in which pre-reduction takes place in a fluidized bed, in which combustion and pre-reducing gases are mixed. SE 419 129 specifies a total coal demand of 700 kg / tonne Fe, a large part of the carbon supplement is contained in the exhaust gases as combustion heat. The energy demand according to the invention is around 400 - 500 kg / ton Fe. In this way, 5 - 30% of the total carbon demand can be fed into the pre-reduction stage.

11 88177

As a further advantage of the invention, it is mentioned that the final exhaust volumes in the processor according to the invention will, as a result of the smaller carbon demand, be considerably smaller than in the corresponding other processes. In addition, where the exhaust gases from the fluidized bed reactor are essentially final combustion, the invention contributes to a more environmentally friendly process. In the process according to the invention, the inconveniences caused by cooled explosive toxic gases, e.g. unburned gases containing CO and H2. Purely plant technology, simpler designs can be achieved. In processes that result in unburned gases, these have normally been combusted with air at some final stage, leading to large exhaust volumes and consequently greater costs. Combustion with air also contributes to an increase in NOx levels in the exhaust gases.

The beneficial effect of the fluidized bed on the amounts of dust in the exhaust gases is noteworthy. With the gases from the flame chamber, the following molten droplets and particles will be trapped by the cold silt particles, immediately cooled to the temperature which rises in the reactor and will not cause any trouble in gas cleaning or return to the flame chamber. . chamber. Possible carbon particles emitted with the exhaust gases, slag-forming substances or the like. will in the same way be taken to be returned to the flame chamber.

In the following, the invention is described in more detail with reference to the accompanying drawings, of which Fig. 1 shows schematically a device for carrying out the method according to the invention.

Fig. 2 shows an enlargement of the flame chamber wall

Fig. 3 shows another embodiment of the device and

Fig. 4 shows a further embodiment of the device. 35

The apparatus of FIG. 1 generally shows a flame chamber 1, a fluidized bed fluidized bed reactor or fluidized bed reactor 2 12 881 77 connected to a particle separator 3. The flame chamber is arranged at a final reduction plant, for example. a converter 4 which is connected to the lower part of the flame chamber through an opening 5 in its upper part.

5

Metal oxide-containing material e.g. ferrous sieve or ore concentrate 6 to be reduced is fed into the lower part of the fluidized bed reactor 2. At the same time through an opening 7, hot gases flow at a temperature of approx. 1400 - 1800 ° C from the flame chamber located below into the reactor and fluidize the feed. The temperature in the flame chamber and also the temperature of the exhaust gases vary depending on which metal oxides are pre-reduced. Ni oxides require higher temperatures than above and Cu oxides lower temperatures. Thus, in the reactor 2 the hot gases are preheated to approx. 600 - 950 ° C, to a temperature below the material's cladding temperature. The temperatures in this case also depend on the metal oxides to be heated, Ni oxides to higher Cu oxides to lower temperatures than the Fe oxides. If the incoming reducing gases temperature is too high, they can be lowered immediately after or before the inlet to the fluidized bed reactor, e.g. by recirculating part of the purified and cooled exhaust gases. Normally, the entire amount of gas is utilized from the flame chamber for: heating the sieve but if the temperature of the sieve tends; to become too high in the fluidized bed reactor, some of the exhaust gases from the flame chamber can instead be used for preheating air, fuel or slag generators.

. Such particles should have a grain size suitable for preheating and reduction. In most cases, particles with a diameter <1 mm have proved suitable. The fluidizing gases then transport to the upper part of the reactor and through a: channel 8 out of the reactor to the particle separator 3. In the figure. .35 shows a vertical cyclone separator particle type separator, but any other suitable separator or suitable separator system can be used as well. The purified exhaust gases are led out of the separator through the outlet 9.

13 88Γ / "/

The separated particles are conducted from the lower part of the cyclone separator either through an feed line 10 back into the fluidized bed reactor 2 or via an input line 11 to the flame chamber. With a device 12, the relationship between materials which are recirculated and materials that are directed directly into the flame chamber can be controlled. In some cases, no feed circulation is needed to the reactor 2, but in order to achieve even and rapid heating of the circulating bed, in most cases, it is advantageous. The mass of the circulating bed has a stabilizing effect on the heat transfer in the reactor without affecting the energy balance itself. The residence time of the particles is extended in a circulating bed and can also be easily controlled which leads to a very flexible process.

Particulate reducing agents such as koi or coke 13 and combustion-entertaining gas such as air, oxygen-enriched air, with e.g. > 17% oxygen, or oxygen gas 14. In a process according to the invention, low carbonaceous reducing agents such as peat, lignite and coal can also conveniently be used. In some processes, the reduction potential of the reducing gases from the final reduction step is sufficient to pre-reduce the ore concentrate. In these cases, the input of reducing agent into the flame chamber can be excluded.

: Sludge generators or fluxes can also be added to the flame chamber or floating bed reactor together with sieve or directly through special inlets. The carbon and the oxygen can also be added directly into the flame chamber through its own inlets.

The conduit 11 branches before the discharge into the flame chamber / into several conduits 15, the number of which may be e.g. 2 - 8 '* *, which in a wreath open out via nozzles 16 in: the flame chamber. If the floating bed reactor is provided with several parallel particle separators, the conduit 11 from each individual separator can open into the flame chamber via a separate nozzle.

In the illustrated method, the nozzles disposing 1 are a wreath in the lower part of the flame chamber. The nozzles reflect the input material obliquely up and inset in the flame chamber 5 so that the input material strikes tangentially imagined horizontal circles in the flame chamber. These circles have a diameter smaller than the cross-section of the flame chamber.

Through the opening 5, hot reducing combustible gases such as CO and H2 flow from the final reduction stage 4 up into the flame chamber. The air or oxygen-containing gas supplied via the nozzles 15 is well mixed with the combustible gases and effectively combust in an oxidizing zone in the middle of the flame chamber the rising gases, which generates heat for melting the input metal oxide-containing material. The obliquely upwardly fed gas given a tangential direction at a suitable velocity results in a cyclone action resulting in a rotary movement of the material in the flame chamber, which contributes to an efficient mixing of gas and particles. At the same time, the molten metal oxide-containing material, as shown in Figure 2, will be thrown out against the walls of the flame chamber 18 and there form a thin layer 19 of metal oxide melt. Uncombusted coke particles 20 are mixed into the metal oxide melt 19 and produce a continuous reduction whereby a thin reducing gas layer 21 is formed on and partially in the melt at the wall. Some of the coke-containing particles follow the melt in the final reduction step.

Of course, materials fed into the flame chamber can be fed through openings in the walls or ceiling of the flame chamber without the use of regular nozzles, advantageously that the input material can be directed in the desired direction. Alit material, e.g. sly and oxygen or possibly air, need not be mixed before the flame chamber, the main thing is that the combustion-maintaining gas is effectively mixed with the gases in the flame chamber and that the metal oxide-containing material can effectively absorb heat from the flames.

15 881 77

The walls of the flame chamber are preferably made up of membrane walls, whose tubes are flooded with water or meadow. The membrane wall cools the layer closest to the wall of the metal oxide melt, which will solidify into a solid layer. The solid layer protects the walls from wear. The molten metal oxide continuously flows down the wall and will melt and pre-reduced to flow down in a final reduction step e.g. a converter 4 connected to the flame chamber.

The reducing gases which rise up in the flame chamber will be completely burned in the oxidizing zone of the flame chamber by the supplied oxygen and passed from the flame chamber 15 through the opening 7 into the reactor 2.

In Figure 1, a device with input of material in the lower part of the flame chamber has been shown. Input in the middle or upper part of the flame chamber may be preferable in some applications. Also there, the feed nozzles are directed so that the ascending reducing gases will burn in hot flames in the center of the chamber and that a reducing layer will be maintained at the walls of the chamber.

In the method of the invention shown in Figure 3, the nozzles 16 are arranged in a wreath in the upper part of the flame chamber. The nozzles direct the input material obliquely down and inset into the flame chamber so that the input material hits tangentially imagined horizontal circles 17 in the - 30 flame chamber. These circles have a diameter smaller than the diameter of the flame chamber. The rotary movement that is upset in the material will throw out molten material on the walls of the chamber 18. The rising gases and the alignment V of the nozzles can be made such that the melt is distributed in the desired manner over the wall.

The pre-reduced and at least partially molten metal oxide containing material flows downstream along the walls of the flame chamber and to the final reduction reactor 4, which may be, for example, a converter. In the reactor, the final reduced metal forms a melt bath 27 on the bottom of the converter. and a slag layer 26 on the metal melt.

5

The pre-reduced liquefied molten material is substantially reduced in the slag layer and in the layer between the slag and the melt to form reducing gases. In the reactor wall just above the slag layer are arranged at least 10 nozzles 24 for injecting oxygen or oxygen-containing gas for combustion of the reducing gas formed. The nozzles are directed tangentially to an imaginary horizontal circle of smaller diameter than the reactor, whereby the gas mixture in the converter will form a swirling motion. The oxygen gas will sweep across the surface of the slag layer and burn the formed reducing gases in immediate connection to their formation at the slag layer and will then heat to the slag layer and the bath. A gas having 17 - 100% oxygen can conveniently be used. A good stirring of the bath e.g. with inert gas, tili contributes to better heat dissipation from the combustion gases to the bath. The gases formed in the final reduction stage rise according to the procedure illustrated in the figure directly straight up in the flame chamber countercurrent to the downstream liquid pre-reduced material. In some cases it may be advantageous to introduce the gases into the flame chamber from the side. This can be done so that combustion in the flame chamber will mainly take place in the flame chamber in an oxidizing zone and furthermore that a reducing zone is maintained in the flame chamber.

. 30

Carbonaceous final reducing agents such as coal or coke can be supplied to the converter via inlet 28 into the metal melt or via an inlet into the slag layer or above the slag layer. Oxygen is fed through the inlet 29.

Fuel and oxygen can be injected into the slag layer or melt to cover part of the energy demand in the final reduction and melting of unmelted metal oxides in the converter.

: 35 17 881 77 20 - 60% of the reducing gases formed can be burned above the slag layer in a converter.

If additional energy to the melt is supplied via electrodes, only 4-20% of the gases formed can be burned above the slag layer. Higher temperatures can damage the electrodes.

Also, plasma heated oxygen or in the regenerative or recuperative way heated oxygen and / or air can be used to burn formed gases above the slag layer. The melt itself can be supplied with energy by light in a plasma heated gas.

For recuperative or regenerative preheating, some of the gases formed can be extracted from the final reduction stage.

Figure 4 shows a device for a somewhat different application of the invention. The flame chamber 1 has in this case a tapered lower part 34 to which the pre-heated metal oxide-containing material feed line 11 is connected. In this case, the intention is to both melt and pre-reduce the preheated material with the hot reducing gases from the final reduction stage, essentially without combustion of the hot gases or without the addition of additional reducing agents. In this case, a very good contact between preheated material and hot should be established in the flame chamber:: reducing gases from the final reduction stage 4. In the application shown in the figure, the lower part 34 of the flame chamber has been made tapered to allow a good mixing there. . The temperature in the lower part can rise to 1600 - 1700 ° C, with melting and reduction occurring very quickly.

The reactions of this embodiment can be carried out substantially: without burning combustion gas, whereby a greater proportion of the reducing gases formed at the final reduction can be burned in conjunction with their formation in the converter itself than if the reducing gases would be needed in a combustion process in the combustion chamber A combustion of the gases in that converter is more economically advantageous than combustion in the combustion chamber.

The rotary movement of the material in the flame chamber, which is needed for the molten material to be thrown out against the walls and not led up into the floating bed reactor 2, is accomplished by feeding exhaust gases via line 33 from the floating bed reactor into the flame chamber. From the particle separator 3, the exhaust gases are conducted via a heat exchanger 30 partly out of the process and partly via a conduit 33 to the upper part of the flame chamber and are fed so that a buzz arises in the material in the flame chamber.

The rotary motion may also be accomplished by other means such as supply of gas from a carburetor in close proximity to the flame chamber. The gas can be combusted in the flame chamber and say Increase the heat content of the flame chamber.

The invention is not limited to the above-described embodiments, but can be varied within the scope of the claimed claims.

Claims (21)

A process for preheating and pre-reducing a metal oxide-containing substance such as concentrate 5 or ore concentrate to produce a pre-reduced product suitable for final reduction, the metal oxide-containing substance being - fed to a final characterized in that a) before feeding to the flame chamber 1, the metal oxide-containing substance is fed to a circulating mass reactor connected to the flame chamber and preheated therein, - hot gases from the flame chamber are fed to the metal oxide-containing material and returned to the 25 reactor in that fed to the flame chamber and that b) the preheated metal oxide-containing substance fed to the flame chamber is at least partially melted and / or preheated using hot reducing gases from the final reduction step. Method according to Claim 1, characterized in that the combustion-maintaining gas is fed into the flame chamber. 35 Method according to Claim 2, characterized in that the gas which maintains the combustion is air. 25 88 1 77 Method according to Claim 2, characterized in that the gas which maintains the combustion is oxygen gas. Method according to Claim 2, characterized in that the combustion-maintaining gas is fed into the flame chamber for burning upwardly flowing hot reducing gases from the final reduction step for melting the metal oxide-containing substance. Method according to Claim 2, characterized in that the carbonaceous substance is fed into the flame chamber. A method according to claim 2, characterized in that the carbonaceous substance and the combustion-maintaining gas 15 are fed into the flame chamber, whereby a hot zone with a high degree of combustion or hot flames and a reducing zone in the vicinity of the flame chamber walls are formed. A method according to claim 7, characterized in that the preheated metal oxide-containing substance is fed to a hot zone with a high degree of combustion and at least partially melted there. A method according to claim 8, characterized in that the carbonaceous substance and the combustion-maintaining gas are fed in such a way that - a hot, oxidizing zone is formed in the middle of the flame chamber to melt the metal oxide-containing substance and at least partially coke the carbonaceous substance, and - molten metal oxide-containing the substance is centrifuged to the walls of the flame chamber, where a reducing region is formed to reduce the molten, metal oxide-containing substance. A method according to claim 1, characterized in that the preheated metal oxide-containing substance 26 881 77 is fed to the lower part of the flame chamber in close connection with the supply of hot reducing gases from the final reduction step so as to provide good contact between the reducing gases and the metal oxide-containing substance 5. A method according to claim 1, characterized in that the gas is fed to the flame chamber to cause a rotational movement in the metal oxide-containing substance fed to the flame chamber so that the molten metal oxide-containing substance is centrifuged to the walls of the flame chamber. A method according to claim 11, characterized in that it is returned from the circulating mass reactor to the exhaust gas and flame chamber to cause a circulating motion. A method according to claim 11, characterized in that the carbonaceous substance is gasified in connection with the flame chamber so that the substance in the flame cannula is circulated. A method according to claim 1, characterized in that the metal oxide-containing substance in the flame chamber is reduced mainly with reducing gases obtained from the final reduction step 25. A method according to claim 1, characterized in that the reducing agent is fed into the flame chamber to reduce the metal oxide-containing substance. 30 Process according to Claim 1, characterized in that the metal oxide-containing substance is preheated in a circulating mass reactor to a temperature which does not exceed the tack temperature of the substance, preferably 600 to 950 ° C. 35 Process according to Claim 1, characterized in that the metal oxide-containing substance is heated in a flame chamber to a temperature in which the substance is essentially molten, preferably 1400 to 1800 ° C. A method according to claim 1, characterized in that in the flame chamber evaporated and molten material, possibly following the exhaust gases from the flame chamber to the circulating mass reactor, is made to condense and solidify or otherwise adhere to the cold particles of the circulating mass reactor. 10 A method according to claim 1, characterized in that the metal oxide-containing material is produced into a molten metal product in three successive steps: a) preheating the metal oxide-containing material in a first process step, b) preheating the preheated material and at least partially wherein the energy content of the gases formed in the second and third process steps is utilized in the same or a previous process step to minimize the energy required to produce the molten metallic product. A method according to claim 1, characterized in that the pre-reduced and at least partially molten metal oxide dip is reduced in a final reduction step in a reactor containing a molten metal bath and a molten slag layer thereon, and in part the combustion gases are combusted with a combustion-maintaining gas is swept over said slag layer. 21. Apparatus for preheating and preheating a metal oxide-containing substance such as concentrate or ore concentrate to produce a pregelatinized product suitable for final reduction, comprising ζβ 88177 - a flame chamber having a for circulating a metal oxide-containing substance in a flame chamber, characterized in that the device comprises 10 a) a circulating mass reactor (2) connected to the top of the flame chamber (1) for preheating the metal oxide-containing substance before feeding it to the flame chamber; (1) for incoming hot exhaust gases, and the top is connected to a particle separator (3) for separating the preheated metal oxide-containing substance from the gases leaving the reactor, and - the particle separator (3) is connected by a return pipe (10) to the lower part of the reactor and by a supply pipe (11) to the flame chamber, 20 and b) for hot reducing gases from the final reduction step (4) of the inlet connected to the lower part (34) of the flame chamber (1).