MXPA05006826A - Method and plant for the heat treatment of sulfidic ores using annular fluidized - Google Patents

Abstract

The invention relates to a method and a plant for the heat treatment of sulfidic ores, in which solids are heated to a temperature of approximately 450 to 1500°C in a fluidized bed reactor (1). In order to improve the energy utilization, it is proposed to introduce a first gas or gas mixture from below through a gas supply tube (3) into a mixing chamber (7) of the reactor (1), the gas supply tube (3) being at least partly surrounded by a stationary annular fluidized bed (35) which is fluidized by supplying fluidizing gas. The gas velocities of the first gas or gas mixture as well as of the fluidizing gas for the annular fluidized bed (35) are adjusted such that the particle Froude numbers in the gas supply tube (3) are between 1 and 100, in the annular fluidized bed (35) between 0.02 and 2 and in the mixing chamber (7) between 0.3 and 30.

Description

METHOD AND PLANT FOR HEAT TREATMENT OF SULFIDIC MENES Field of the Invention The present invention relates to a method for the heat treatment of sulfidic ores in particular, wherein the finely granulated solids are treated at a temperature of 450 ° C to about 1 500 ° C in a first reactor. fluidized bed, and to a corresponding plant.

BACKGROUND OF THE INVENTION Said method and plant for the treatment of sulfidic ores containing gold are known, for example, from DE 196 09 286 Ethyl acetate. In that case, the ore is fluidized in a fluidized circulation bed of a calcination reactor by means of an oxygen-containing gas, the metal sulphides being converted into metal oxides and an exhaust gas containing SO2 is obtained. The calcination of sulfide ores, such as for example zinc blende, in a fixed fluidized bed furnace at temperatures between 500 ° C and 1 100 ° C is also known, with air being supplied. In this calcining of the zinc blende in a fixed fluidized bed furnace, up to 1,000 metric tons of blende per day can be processed. It is considered that the use of heat treatment energy achieved by using a fixed fluidized bed needs improvement. One reason for this is that the mass and thermal transfer is rather moderate because of the comparatively low degree of fluidization. Furthermore, in the case of the fixed fiuidized beds, the fine particles are discharged too quickly from the reactor, so that the retention time in the plant is not suitable for a complete reaction. This problem arises especially in the case of fluidized circulation beds due to the greater degree of fluidization, although the conditions of better mass and thermal transfer prevail. Since sulfidic ores used for heat treatment, such as for example gold ore, blende or zinc concentrate, they become increasingly thin, for example with a grain size fraction below 45 μm of 75 %, only a suitable calcining result can be achieved with the known methods and plants hardly. Furthermore, in the case of known methods and plants, the temperature in the reactor can rarely be regulated, further damaging the calcination result.

Objective and Compendium of the Invention Therefore, the aim of the present invention is to provide a method for the heat treatment of sulfidic ores, which can be carried out more efficiently and is distinguished in particular by the best calcination results together with the good conditions for heating and mass transfer. According to the invention, this objective is achieved by a method as mentioned above in which a first gas or gas mixture is introduced from below through a gas supply pipe preferably arranged centrally (central tube) within a region of the reactor mixing chamber, the central tube being surrounded, at least partially, by a fixed fluidized bed which is fluidized by supplying fluidized gas, and in which the velocities of the first gas or gas mixture, as well as the of the fluidizing gas for the annular fluidized bed are regulated so that the Froude numbers of the particles in the central tube are between 1 and 100, in the annular fluidized bed between 0.02 and 2 and in the mixing chamber between 0.3 and 30. In the method of the invention, the advantages of a fixed fluidized bed, such as a longer retention period, and the advantages of a circulating fluidized bed, such as A good transfer of mass and heat can surprisingly combine with each other during the heat treatment, such as, for example, the calcination of sulfide ores, while avoiding the disadvantages of the two systems. When it passes through the upper region of the central tube, the first gas or gaseous mixture entrains solids from the fixed annular fluidized bed, which is referred to as the annular fluidized bed, within the mixing chamber, so that, due to the differences in high speed between the solids and the first gas , a highly mixed suspension is formed and an optimal transfer of heat and mass between the two phases is achieved. By regulating the height of the bed in the annular fluidized bed, as well as the gas velocities of the first gas or the gas mixture and the fluidizing gas, the solids loading of the suspension on the region of the orifice of the central tube can be varied within wide margins, so that the loss of pressure of the first gas between the region of the orifice of the central tube and the upper outlet of the mixing chamber may be between 1 mbar and 100 mbar. In the case of a high load of solids in the suspension in the mixing chamber, a large part of the solids will separate from the suspension and fall back into the annular fluidized bed. In this way, the temperature in the annular fluidized bed can also be regulated by the amount of heated particles that have been separated. This recirculation is called internal recirculation, the stream of solid solids that recirculate in this internal circulation is normally significantly higher than the amount of solids supplied to the reactor from outside. The (less) amount of the non-precipitated solids is discharged from the mixing chamber together with the first gas or gas mixture. The retention time of the solids in the reactor can be varied within a wide range by choosing the height and cross-sectional area of the annular fluidized bed and can be adapted to the desired heat treatment. The amount of solids that are drawn from the reactor with the gas stream can be complete or at least partially recirculated from the reactor, the recirculation being fed opportunely into the fixed fluidized bed. The solids stream thus recirculated to the annular fluidized bed normally runs in the same order of magnitude as the stream of solids supplied to the reactor from outside. With the method of the invention, it is consequently possible to achieve on the one hand a high charge of solids and at the same time a particularly good mass and heat transfer. Apart from the excellent use of energy, another advantage of the method according to the invention consists in the possibility of quickly, easily and reliably adapting the energy transfer of the method and mass transfer with the requirements by changing the flow rates of the first gas or gas mixture and fluidizing gas. The heat transfer can further be intensified if the reactor is provided downstream with a second reactor, into which a gaseous mixture charged with solids is introduced from the first reactor. This is preferably carried out from below through, for example, a central gas supply tube within a mixing chamber, the gas supply tube being at least partially surrounded by a fixed annular fluidized bed which is fluidized supplying fluidized gas. In principle, a single reactor is suitable for carrying out the method according to the invention. However, the combination of a reactor with a second reactor of a similar type of construction to form a reactor platform allows the total retention time of the solids in the plant to be increased differently. To ensure a particularly effective heat transfer in the mixing chamber and a sufficient retention time in the reactors, the gas velocities of the first gas mixture and the fluidizing gas are preferably adapted for the fluidized bed so that the Froude numbers of the dimensionless particles (Frp) are 1.15 to 20, particularly 3, 95 and 11.6, in the central tube, 0.11 to 1.15, in particular between 0.11 and 0.52, in the annular fluidized bed, and / or 0.37 to 3.7, in particular between 0.53 and 1.32, in the mixing chamber. The Froude numbers of the particles are each defined by the following equation: with u = effective gas flow velocity in m / s Pf = effective density of the fluidising gas in kg / m3 ps = density of a solid particle in kg / m3 dp = average diameter in m of the particles in the reactor inventory (or the particles that form) during the operation of the reactor g = gravitational constant in m / s2. When this equation is used, it should be considered that dp does not indicate the average diameter (d50) of the material used, but the average diameter of the reactor inventory formed during the operation of the reactor, which can differ significantly in both directions from the average diameter of the reactor. used material (primary particles). It is also possible that particles (secondary particles) with an average diameter of 20 to 30 μm are formed during, for example, heat treatment from a very finely grained material with an average diameter of, for example, 3 to 10 μm. On the other hand, some materials, for example ores, are decrepitated during heat treatment. In a development of the idea of the invention, it is proposed to regulate the bed height of the solids in the reactor or the reactor platform so that the annular fluidized bed extends beyond the end of the upper orifice of the central tube in a few centimeters, and thus the solids are constantly introduced into the first gas or the gas mixture and carried by the gas stream to the mixing chamber located on the region of the orifice of the central tube. In this way, a high load of solids of the suspension is achieved on the region of the orifice of the central tube. By the method according to the invention, all types of sulfide ores, in particular also those containing gold, zinc, silver, nickel, copper and / or iron, can be heat treated effectively. In particular, the method is suitable for the calcination of gold ore or zinc blende. The intense transfer of mass and heat and the adjustable retention time in the reactors allow a particularly high degree of conversion of the calcined material to be achieved. The generation of the amount of heat necessary for the operation of the reactor can be carried out in any manner known to the expert for this purpose. According to a preferred embodiment of the present invention, it is established that, for the calcination, the reactors are supplied with an oxygen-containing gas, for example with an oxygen content of about 20 vol-%, which is introduced into the beds fluidized rings of the reactors. The gas can be air, air enriched with oxygen or some other oxygen-containing gas. The oxygen-containing gas is preferably introduced into the reactor or reactors at a temperature of about 25 ° C to 50 ° C. The process of calcination of the sulfide ores with excess oxygen to form metal oxides is exothermic, so that usually no more heat has to be supplied to the reactor or the reactor platform. The use of energy can be further improved in the case of the method according to the invention by supplying heat to or extracting from the first and / or second reactor in the annular fluidized bed and / or in the mixing chamber. Thus, in the case of an exothermic reaction, for example, the heat generated can be used in the reactor for current generation for example. Preferably a cooling device is provided downstream of the second reactor, for cooling the solid charged gaseous mixture emerging from the reactor at an appropriate temperature for the subsequent treatment of less than 400 ° C, in particular to approximately 380 ° C. This cooling device can also be used for example to generate water vapor, whereby the energy utilization of the whole method is further improved. A separator, for example a cyclone or the like, can be placed downstream of the reactor platform. The separated solids of the exhaust gases can be returned from the separator inside the reactor platform, for example within the annular fluidized bed, from one or more reactors, or passing them to another cooling device. The retention time of the solids in the reaction platform can be varied in this way. In addition, the bed height of the solids in one or more reactors can be deliberately adapted to the requirements. The bed height in the annular fluidized bed in this case also exerts influence on the temperature set in the annular fluidized bed, since more particles are entrained within the mixing chamber and separated from it in a heated state when there is a greater height of the bed. In this way, the temperature in the reactor can be deliberately regulated by the amount of solids recirculated from the separator. The preferably provided downstream of the separator is a gas cleaning platform with an electrostatic hot gas precipitator and / or a wet gas treatment, in which at least part of the exhaust gases separated from the solids in the separator is then cleaned The cleaned exhaust gases can then be returned, for example in the form of a preheated fluidizing gas, into the annular fluidized bed of the first and / or second reactor. Part of the exhaust gas separated from the solids in the separator can also be supplied to a plant to produce sulfuric acid. The exhaust gases containing SO2 from the reactor platform can be used in this way to produce a by-product. The coarse-grained solids and / or the calcination residue are removed from the annular fluidized bed of the first and / or second reactor and passed to another cooling device, for example a fluidized-bed cooler. The discharge of the solids or the calcination residue can be carried out in this case in a discontinuous manner, whereby the quantity of solids in the reactor platform can be regulated at the same time. A plant according to the invention, which is in particular suitable for carrying out the method described above, has a reactor which constitutes a fluidized bed reactor for the heat treatment of sulfidic ores, the reactor having a gas supply system which is formed so that the gas flowing through the gas supply system draws solids from the fixed annular fluidized bed, which at least partially surrounds the gas supply system, into the mixing chamber. Preferably, it surrounds the gas supply system, inside the mixing chamber. Preferably, this gas supply system extends into the mixing chamber. However, it is also possible to allow the gas supply system to terminate below the surface of the annular fluidized bed. The gas is then introduced into the annular fluidized bed for example via side openings, which entrain solids from the annular fluidized bed within the mixing chamber due to its flow rate. According to a preferred aspect of the invention, the gas supply system has a central tube that extends upwards substantially vertically from the lower region of the reactor, which is at least partially surrounded in an annular shape by a chamber in which the fixed annular fluidized bed is formed. The annular fluidized bed does not have to be annular, but other forms of the annular fluidized bed are also possible, depending on the geometry of the central tube and the reactor, as long as the central tube is at least surrounded by the fluidized bed cancel. Of course, two or more central tubes with different or identical dimensions or shapes are also provided in the reactor. However, preferably at least one of the central tubes is disposed approximately centrally with reference to the cross-sectional area of the reactor. According to a further embodiment of the present invention, the central tube has openings in its coating surface, for example in the form of grooves, so that during the operation of the reactor the solids constantly enter the central tube through the openings and are dragged by the first gas or gas mixture from the central tube inside the mixing chamber.

To increase the yield of the plant or the retention time of the solids, instead of a single reactor there can also be a series of reactors, in particular two, connected to form a reactor platform. The reactors preferably have in each case an annular chamber for an annular fluidized bed and a mixing chamber for the formation of a fluidized circulation bed, the central tube of a downstream reactor being connected to the outlet of the exhaust gas of the reactor provided with current above it. According to a preferred embodiment, a separator, particularly a cyclone, is placed downstream of the reactor, or of the reactor platform, for the separation of solids. The separator may have a solids duct that reaches the annular fluidized bed of the first reactor and / or a solids duct that reaches the annular fluidized bed of a second reactor possibly placed downstream. If a cooling device is provided downstream of the reactor platform, the gaseous mixture charged with solids discharged from the reactor platform can be cooled before a subsequent treatment at the temperature required for this. A recovery boiler consisting of banks of cooling tubes can be used for example as the cooling device, it being possible for the banks of the cooling tubes to serve at the same time for the generation of steam. In addition, the temperature required for the heat treatment can be regulated exactly in the first and / or second reactor by means of temperature control elements. For this purpose, the reactor can be provided in the form of a natural circulation boiler with cooling elements and membrane walls. In order to provide a reliable fluidization of the solids, and to form a fixed fluidized bed, in the annular chamber of the first reactor and / or of the other reactors is arranged a gas distributor that divides the chamber into a fluidized bed upper region and a lower gas distributor chamber. The gas distributor chamber is connected to a supply conduit for fluidized gas. Instead of the gas distributor chamber, a gas distributor composed of tubes can also be used. Preferably, the separator of the reactor or of the reactor platform is connected to a supply conduit that reaches the annular chamber of the reactor, so that the exhaust gas, possibly cleaned beforehand, can be used as a preheated fluidized gas. As an alternative, or in addition to this, a dedusting device and / or plant for producing sulfuric acid can be located downstream of the separator of the reactor or the reactor platform. In the annular fluidized bed and / or the reactor mixing chamber, means for diverting the solids and / or fluids of fluids according to the invention are placed. It is possible, for example, to place an annular pourer, whose diameter is between that of the central tube and that of the reactor wall, in the annular fluidized bed, so that the upper edge of the pourer protrudes beyond the level of the solids obtained during the operation, while the lower edge of the pourer is disposed at a distance from the gas distributor or the like. Therefore, solids that fall out of the mixing chamber near the reactor wall must first pass through the spout at the bottom edge thereof, before they can be carried away by the gas flow from the central tube back to the mixing chamber. In this way, an exchange of solids is carried out in the annular fluidized bed, so that a more uniform time of retention of the solids in the annular fluidized bed is obtained. The developments, advantages and possibilities of application of the invention also result from the following description of an exemplary embodiment and of the drawing. All the features described and / or illustrated in the drawing form the substance object of the invention per se or in any combination, independently of its inclusion in the claims or its previous reference.

BRIEF DESCRIPTION OF THE DRAWINGS The single figure shows a process diagram of a method and a plant according to an exemplary embodiment of the present invention.

Detailed Description of a Preferred Embodiment In the method shown in the figure, which is particularly suitable for the heat treatment of sulfide ores, the solids are introduced into a first reactor 1 through a supply conduit 2. The reactor 1, which is for example cylindrical, has a central tube 3, which is placed approximately coaxial to the longitudinal axis of the reactor and extends substantially vertically upwards from the reactor. bottom of the reactor 1. Located in the region of the bottom of the reactor 1 is an annular gas distributor chamber 4, which is closed at the top by a gas distributor 5 having openings. A supply conduit 6 opens in the gas distributor chamber 4.

Arranged in the upper vertical region of the reactor 1, which forms a mixing chamber 7, there is a discharge conduit 8, which opens to a second reactor 9. The second reactor 9 is very similar in construction to the first reactor 1. Extending from the bottom of the reactor 9 substantially vertical upwards is a central tube 10, which is connected to the discharge conduit 8 of the first reactor 1, and is placed approximately coaxial to the longitudinal axis of the reactor 9. Arranged in the region of the bottom from the reactor 9 is an annular gas distributor chamber 11, which is closed at the top by a gas distributor 12 having openings. A supply conduit 13 is opened out in the gas distribution chamber 11. Another supply conduit 14 has been placed to introduce the solids to the reactor 9 during the ignition of the plant. The temperature control elements 15 and 16, which, for example, flow through water, are arranged on the gas distributors 5 and 12, respectively, of the two reactors. In addition, the walls of the reactors 1 and 9 are formed as the membrane walls 17 and 18, respectively, which are connected to other temperature control elements which are not shown in the figure and which, for example, flow through water. In this way, the reactors form a kind of natural circulation boiler. Arranged in the upper vertical region of the second reactor 9, which forms a mixing chamber 19, there is a recovery boiler 21 provided with banks of cooling tubes 20. Through a conduit 22, the recovery boiler 21 is connected to a separator, which is formed as a cyclone 23. A solids duct 24 returns the solids of a floating tank 25, provided downstream of the cyclone 23, in the reactors 1 or 9, or supplies the solids to another cooling device 26.

Arranged on the gas distributors 5 and 12 of the two reactors are discharge conduits 27 and 28 for coarse-grained solids and / or calcining residue, which are connected to another cooling device 26. The cooling device 26 is formed as a fluidized bed cooler wherein the product stream is subjected to fluidizing air and cooled by a cooling element 29. Through a conduit 30, the exhaust gas separated from the solids of cyclone 23 is supplied to a cleaning platform of gas having an electrostatic hot gas precipitator 31 and wet gas cleaner 32. The dustless exhaust gas can be transferred to a plant 33 for the production of sulfuric acid and / or through conduit 34 as a fluidizing gas in the reactors 1 and 9 through conduits 6 and 13, respectively. Another gas, which may also be a different gas, may in this case be supplied to the fluidizing gas after cleaning. During the operation of the plant, solids can be introduced into reactor 1 via supply conduit 2, so that a layer annularly surrounding the central tube 3, which is referred to as an annular fluidized bed 35, is formed in the gas distributor 5. The fluidizing gas introduced in the gas distributor chamber 4, through of the supply conduit 6, flows through the gas distributor 5 and fluidizes the annular fluidized bed 35, so that a fixed fluidized bed is formed. The velocity of the gases supplied to the reactor 1 is adjusted so that the Froude number of the particles in the annular fluidized bed 35 is approximately 0.11 to 0.52. By supplying other solids in the annular fluidized bed 35, the level of the solids in the reactor 1 increases to such an extent that solids enter the orifice of the central tube 3. At the same time, a gas or a gas mixture is also introduced into the reactor 1 through the central tube 3. The velocity of the gas supplied to the reactor 1 is preferably regulated so that the Froude number of the particles in the central tube 3 is approximately 3.95 to 11.6 and in the mixing chamber 7. about 0.53 to 1.32. Due to these high gas velocities, the gas flowing through the central tube 3 draws solids from the fixed annular fluidized bed 35 into the mixing chamber 7 as it passes through the region of the upper orifice. Due to the lateral inclination of the level of the annular fluidized bed 35 in comparison with the upper edge of the central tube 3, the solids flow towards this edge in the central tube 3, whereby a highly mixed suspension is formed. The upper edge of the central tube 3 can be smooth, corrugated or serrated or have side openings. As a result of the reduction of the flow velocity by expansion of the nozzle and / or by impact on one of the walls of the reactor, the solids entrained in the mixing chamber 7 rapidly lose speed and partially return to the annular fluidized bed 35. The amount of non-precipitated solids is discharged from the reactor 1 together with the gas stream through the conduit 8 and passes to the reactor 9. Between the reactor regions of the fixed annular fluidized bed 35 and the mixing chamber 7 a circulation of solids is thus obtained which ensures an appropriate heat transfer. Before further processing, the solids discharged through the conduit 8 are treated in the second reactor 9 in the manner explained above in reference to the reactor 1, so that the fixed fluidized bed 36 is similarly formed on the gas distributor 12 in the reactor 9 by solids separated from the mixing chamber 19 In addition, the dust separated in the hot gas electrostatic precipitator 31 is returned through a recirculation duct to the fixed annular fluidized bed 36 of the second reactor 9. The Froude numbers of the particle in the second reactor 9 correspond approximately to the of the first reactor 1. The bed height of the solids in reactors 1 and 9 is regulated not only by the supply of solids through conduit 2 but mainly also by the amount of solids returning from cyclone 23 to the reactors and above all by means of the amount of solids extracted from the reactors through conduits 27 or 28. The solids removed from cyclone 23 and / or direct The reactors 1 and 9 are cooled in the fluidized bed cooler 26 to a temperature suitable for further processing. After cleaning the hot gas electrostatic precipitator 31 and the wet gas cleaning 32, the exhaust gas separated from the solids in the cyclone 23 can be partially supplied to the reactors, as a preheated fluidizing gas, or to the sulfuric acid plant. The invention will be described below with reference to the two examples that demonstrate the inventive idea but are not limited thereto.

EXAMPLES Example 1 Calcination of the gold ore In a plant corresponding to the figure, with an area of 1 200 kg / h, a gold ore was supplied dry and classified with a gold content of approximately 5 ppm, ie 5 g / t, and a maximum grain fraction of 50 μm, containing 1.05 wt-% organic carbon 19.3 wt-% CaCO3 12.44 wt-% Al2O3 2.75 wt-% FeS2 64.46 wt-% substances inert (for example SiO2), In continuous operation to reactor 1, whose upper part had a diameter of 800 mm. In addition, 2 500 Nm3 / h of air with a temperature of 520 ° C inside the reactor 1 was introduced through the central tube 3 and through the conduit 6 in the form of fluidizing gas. The Froude number of the particle was in this case between 3.95 and 6.25 in the central tube 3, between 0.84 and 1.32 in the mixing chamber 7 and between 0.32 and 0.52 in the bed fluidized annular 35. The retention time of the gold ore in reactor 1 was between 5 and 10 minutes, with a temperature between 600 ° and 780 ° C established in the reactor. 0.5 to 6.0 vol% residual oxygen was measured in the exhaust gas. The organic carbon content in the product after heat treatment was less than 0.1%.

Example 2 Calcination of the zinc blende In a plant corresponding to the figure, 1.42 t / h of zinc blende with a temperature of about 25 ° C was supplied to the reactor from a loading bunker with a capacity of approximately 200 m3. through the conduit 2 and a dosing device inside the fluidized bed 35. At the same time, about 16 600 Nm3 / h of air with a temperature of 47 ° C and a temperature of 47 ° C were introduced into the annular fluidized bed through the conduit 6. pressure of approximately 1.2 bar, containing 77, l% N 20.4 vol-% O2 2.5 vol-% H2O, Approximately 60 200 Nm3 / h of air and additionally 3 000 Nm3 of air cooler exhaust from the fluidized bed cooler 26, with a temperature of 150 ° C to the reactor 1 through the central pipe 3, so that the total amount of air transmitted to the central pipe 3 was approximately 63 200 Nm3 / h. The air had a temperature of 35 ° C and a pressure of 1.07 bar and contained 77, l vol-% N 20.4 vol-% O2 2.5 vol-% H2O, The number of Froude of the particle was in this case between 4.4 and 11.6 in the central tube 3, between 0.53 and 1.15 in the mixing chamber 7 and between 0.11 and 0.3 in the fluidised annular bed 35. The reaction of the blende of sulfidic zinc with free oxygen from the fluidizing air to form the metal oxide originated a temperature of 930 ° C which was established in reactor 1. At the same time, about 15.4 MW of heat was extracted from the reactor 1 through the cooling element 15 and the membrane wall 17 and used to generate saturated steam from the cooling water. The temperature in the region of the duct 8 at the outlet of the reactor 1 was thus reduced to 800 ° C. To prevent enrichment of coarse material in the reactor 1, about 0.16 t / h of the product with a temperature of 901 ° C in discontinuous operation through the conduit 27 in the form of coarse-grained precipitation was withdrawn from the fluidized annular bed 35. and was passed to the fluidized bed cooler 26. The central tube 10 of the second reactor 9 was passed through the conduit 8, a gaseous mixture charged with solids with a pressure of 1.049 bar comprising 110.9 t / h of solids and approximately 79 600 Nm / h of exhaust gas, containing 12.1 vol-% SO2 77.2 vol-% N 2.5 vol-% O2 8.2 Vol-% H2O. In addition, reactor 9 was supplied through line 13 for fluidization, about 17 350 Nm3 / h of air with a temperature of 43 ° C with a pressure of about 1.18 bar, containing 77, l vol-% N 20, 4 vol-% O2 2.5 vol-% H2O.

During the start-up operation, 5 t / h of solids at a temperature of 25 ° C were charged to the reactor 9 through the conduit 14 at the same time. The gaseous mixture charged with solids was cooled to 480 ° C in the mixing chamber 19 from reactor 9, with a total of approximately 23.6 MW of heat that was moved from reactor 9 by cooling element 16, membrane wall 18 and recovery boiler 21 and was used to generate saturated steam from the Cooling water. The cooling element 16 was used, in this case, in the form of a steam superheater with an overheating temperature of 400 ° C.

It was moved from the reactor 9 through the conduit 22, approximately 96 200 Nm3 of gaseous mixture charged with solids with a temperature of 380 ° C and a pressure of 1.018 bar, which was charged with 213.5 t / h of solids and had the following composition: 9.4 vol-% SO2 77.8 vol-% N 5.5 vol-% O2 7.3 vol-% H2O In cyclone 23, the exhaust gas was separated from the solids to the point that approximately 96 200 Nm3 / h of air with a powder content of 50 g / Nm3 (4.81 t / h solids) was passed to the electrostatic precipitator with hot gas 31 through conduit 30. There, the exhaust gas was dusted to a powder content of 50 mg / Nm and passed for cleaning with wet gas 32 and to the sulfuric acid plant 33 downstream. From the cyclone 23, approximately 208 t / h of solids with a temperature of 380 ° C were passed first to the floating tank 25, serving as a regulating vessel, and divided in such a way that 76.2 t / h was passed into the bed fluidized annulus 35 of the first reactor 1, approximately 100.9 t / h inside the annular fluidized bed 36 of the second reactor 9 and 31 t / h inside the fluidized bed cooler 26.

In this way, it was possible for the bed height of the annular fluidized beds 35 and 36, which are respectively formed in the two reactors 1 and 9, to be adjusted to approximately 1 m. The solids were then cooled in the cooler of the fluidized bed 26 by the cooling element 29 at a temperature lower than 150 ° C, being eliminated with an amount of heat of approximately 1.7 MW. As a result, a total of approximately 40.8 MW was removed from the plant and converted to 55.2 t / h of superheated steam at a pressure of 40 bar and a temperature of 400 ° C. The product discharged from the fluidized bed cooler 26 was mixed with about 4.8 t / h of solids at a temperature of about 380 ° C which was separated from the exhaust gas of the cyclone 30 by the electrostatic precipitator with hot gas 31. The flow of the product discharged as a whole from the plant was therefore about 36.54 t / h at a temperature of about 182 ° C.

In this way, it was possible that both a zinc blende and a zinc blende concentrate with a fraction of the size of a grain less than 45μm of 75% calcine in the plant in such a way that the final product contains 0.3 wt- % sulfur sulfur and 1.8 wt-% sulphate sulfur.

List of Reference Numbers: I (first) reactor 2 supply conduit (solids) 3 central pipe (gas supply pipe) 4 gas distribution chamber 5 gas distributor 6 supply conduit (gas) 7 mixing chamber 8 conduit 9 (second) reactor 10 central pipe (gas supply pipe) II gas distribution chamber 12 gas distributor 13 supply conduit (gas) 14 supply conduit (solids) 15 temperature control element 16 temperature control element 17 membrane wall 18 membrane wall 19 mixing chamber 20 cooling tube bank 21 recovery boiler 22 duct 23 cyclone 24 duct 25 floating tank 26 fluidized bed cooler 27 duct 28 duct 29 cooling element 30 duct 31 electrostatic precipitator with gas hot 32 wet gas cleaner 33 plant to produce sulfuric acid 34 duct 35 fluidized annular bed 36 fluidized annular bed

Claims (24)

1. Claims 1. A method for the heat treatment of sulfidic ores in particular, wherein the solids are treated at a temperature of 450 ° C to about 1 500 ° C in a fluidized bed reactor, characterized in that a first gas is introduced. or gaseous mixture from below through a preferably central gas supply pipe within a reactor mixing chamber, the gas supply pipe being at least partially surrounded by a fixed annular fluidized bed which is fluidized supplying fluidized gas, and in which the velocities of the first gas or gas mixture, as well as those of the fluidizing gas for the annular fluidized bed are regulated so that the Froude numbers of the particles in the gas supply pipe are between 1 and 100, in the annular fluidized bed between 0.02 and 2 and in the mixing chamber between 0.3 and 30.
2. 2. The method as claimed in claim 1, characterized in that the reactor is A downstream reactor is provided, into which a gaseous mixture charged with solids is introduced from the first reactor from below through a preferably central gas supply tube into a mixing chamber, the gas supply pipe being surrounded at least partially by a fixed annular fluidized bed which is fluidized supplying fluidizing gas. The method as claimed in claim 1 or 2, characterized in that the Froude number of the particle in the gas supply tube is between 1.15 and 20, particularly between 3.95 and 11.6. The method as claimed in any of the preceding claims, characterized in that the Froude number of the particle in the annular fluidized bed is between 0.11 and 1.15, particularly between 0.11 and 0.52. The method as claimed in any of the preceding claims, characterized in that the Froude number of the particle in the mixing chamber is between 0.37 and 3.7, particularly between 0.53 and 1.32. The method as claimed in any of the preceding claims, characterized in that the bed height of the solids in each reactor is regulated such that the annular fluidized bed extends beyond the end of the upper orifice of the gas supply pipe. and in that the solids are constantly introduced into the first gas or gas mixture and are carried by the gas stream into the mixing chamber located on the region of the orifice of the gas supply pipe. The method as claimed in any of the preceding claims, characterized in that the sulfide ore, which contains gold, zinc, silver, copper, nickel and / or iron, is used as the initiator material. The method as claimed in any of the preceding claims, characterized in that at least one reactor is supplied with an oxygen-containing gas, for example air with an oxygen content of about 20 vol-% through the supply tube. of gas and / or within the annular fluidized bed. The method as claimed in any of the preceding claims, characterized in that the heat is supplied to or extracted from at least one reactor in the annular fluidized bed and / or in the mixing chamber. The method as claimed in any of the preceding claims, characterized in that the downstream provided with at least one reactor is a cooling device, in which the gaseous mixture charged with reactor solids is cooled to a temperature below of 400 ° C, in particular at about 380 ° C. The method as claimed in any of the preceding claims, characterized in that the downstream provided with at least one reactor is a separator, for example a cyclone, from which the separated solids of the exhaust gases are supplied to the reactor. first and / or second reactor or another cooling device. 12. The method as claimed in claim 11, characterized in that at least part of the exhaust gases separated from the solids in the separator is supplied to the first and / or second reactor in the form of fluidizing gas, in particular after treatment in a downstream gas cleaning platform, such as an electrostatic hot gas precipitator and / or a wet gas treatment. The method as claimed in claim 11 or 12, characterized in that at least part of the exhaust gases separated from the solids in the separator is supplied to a plant to produce sulfuric acid. 14. The method as claimed in any of the preceding claims, characterized in that the coarse-grained solids and / or the calcination residue are removed, in particular in discontinuous form, from the annular fluidized bed of the first and / or second reactor and are passed to another cooling device. 15. A plant for the treatment of sulfidic ores in particular, in particular for performing a method as claimed in any of claims 1 to 14, comprising a reactor that constitutes a fluidized bed reactor, characterized in that the reactor has a system of gas supply which is formed so that the gas flowing through the gas supply system draws solids from a fixed annular fluidized bed, which surrounds at least the gas supply system, into the mixing chamber. The plant as claimed in claim 15, characterized in that the gas supply system has at least one gas supply pipe extending upward substantially vertically from the lower region of the reactor into a mixing chamber. of the reactor, the gas supply pipe being partially surrounded by an annular chamber in which the fixed annular fluidized bed is formed. 17. The plant as claimed in claim 16, characterized in that the reactor is provided downstream of a second reactor, which has a gas supply pipe, which is connected to a discharge conduit for gas mixtures charged with gas. solids provided at the upper ends of the first reactor and is formed so that the gas flowing through the gas supply pipe carries solids from the fixed annular fluidized bed, which at least partially surrounds the gas supply pipe, inside the mixing chamber. The plant as claimed in claim 16 or 17, characterized in that the gas supply pipe is arranged approximately centrally with reference to the cross-sectional area of the reactor. 19. The plant as claimed in claim 18, characterized in that a solids separator, in particular a cyclone, is provided downstream of the second reactor, for the separation of solids, and because the solids separator has a solids duct that leads to the annular fluidized bed of the first and / or second reactor. 20. The plant as claimed in claim 18 or 19, characterized in that a cooling device, in particular a boiler with banks of cooling tubes, is provided downstream of the second reactor. 21. The plant as claimed in any of claims 18 to 20, characterized in that the temperature control elements, in particular a natural circulation boiler with cooling elements and membrane walls, are provided in the first and / or second reactor. 22. The plant as claimed in any of the reactions 18 to 21, characterized in that a gas distributor dividing the annular chamber into an upper fluidized bed region and a lower chamber of the gas distributor is provided in the first and / or second reactor, and in that the chamber of the gas distributor is connected to a supply conduit for the fluidizing gas. The plant as claimed in any of claims 19 to 22, characterized in that the first and / or second reactor has a supply conduit leading to the annular chamber and is connected to an exhaust gas conduit of the separator provided with current. down the second reactor. 24. The plant as claimed in any of claims 19 to 23, characterized in that a dedusting device and / or a plant for producing sulfuric acid is provided downstream of the separator.