EA037686B1 - Method and apparatus for treating a leaching residue of a sulfur-containing metal concentrate - Google Patents

Abstract

The invention describes a process for treating a leaching residue comprising from 30 to 60 wth.% of elemental sulfur generated as filter cake in a leaching of a sulfur-containing metal concentrate. In this process, the leaching residue is fed into a reactor (20), wherein a fluidizing gas is injected into the reactor to form a fluidized bed comprising at least a portion of the leaching residue. The leaching residues are heated in the presence of inert particles which are SiO2 particles to a temperature between 600 and 900°C in an oxidizing atmosphere to produce calcined particles and SO2, which is then used to produce sulphuric acid. At least 60 wt.% of the inert particles are removed from the fluidized bed through an outlet conduit (22) for removing the inert particles from the fluidized bed, while at least 60 wt.% of the calcined particles are removed together with a gas stream comprising off-gases and the fluidizing gas through an offtake conduit (21) for the calcined particles obtained from the leaching residue together with the off-gas from the reactor (20), wherein the diameter of at least 70 wt.% of the calcined particles is smaller than 60 m and/or the diameter of at least 70 wt.% of the inert particles is between 0,05 to 3 mm, the average residence time of the leaching residue in the reactor is from 20 to 200 min, and the inlet velocity of the fluidizing gas is between 0,2 and 2 m/s.

Description

This invention relates to a method and apparatus for treating leach residue from leaching of sulfur-containing metal concentrates, in which the leach residue is fed to a reactor where a fluidizing gas is introduced to produce a fluidized bed containing at least a portion of the leach residue, in which the leach residue is heated in the presence of inert particles to a temperature of 600 to 900 ° C in an oxidizing atmosphere to obtain calcined particles and SO2.

Direct leaching of zinc sulphide concentrate is a commonly used zinc production technology. This method generates a significant amount of elemental sulfur, which is currently sent to waste dumps due to the lack of proven solutions for its processing. Polymetal contamination and poor leach resistance make it increasingly difficult to obtain permission from the competent authorities for long-term dumping of this sulfur-containing waste.

A typical dry residue composition is as follows:

Component Range Preferred range Total S 40-70% of the mass. 45-65% of the mass. Elemental S 30-60% of the mass. 35-55% of the mass. PL 1-20% of the mass. 2-15% of the mass. Fe 3-20% of the mass. 5-15% of the mass. SiO ₂ 3-20% of the mass. 5-15% of the mass. Zn 0.1-10% of the mass. 1-5% of the mass. Ag 100-1000 g / t 200-600 g / t

This composition is taken as the basis for this invention. Sulfur is burned to SO ₂ , non-combustible substances contained in the material are separated in the form of a solid product, consisting mainly of silicon oxide, lead, zinc and iron, and also containing up to 0.1 wt.% Silver. This method makes it possible to dispose of a solid product, namely the product of roasting Fe and Pb, in a lead smelting furnace, to extract silver, as well as to obtain steam and sulfuric acid.

For further disposal of metal compounds, especially silver, it is necessary to burn the contained sulfur to SO2. Such firing is carried out, for example, in a fluidized bed, for example, as proposed in WO 2011/076995. In this case, the sulfur-containing leach residue, or part of it, is sent to a fluidized bed treatment in which the residue is burned to sulfur dioxide and the valuable metals contained in the leach residue are recovered. Sand is added to the fluidized bed to avoid agglomeration.

However, it can be difficult to separate the sand particles from the valuable metal compounds afterwards.

Thus, it is an object of the present invention to provide a method and associated apparatus for calcining sulfur-containing leach residues while minimizing agglomeration as well as ensuring complete separation of the calcined material.

This problem is solved using the method according to claim 1 of the claims, which proposes a method of utilization of the leach residue containing from 30 to 60 wt% of elemental sulfur obtained in the form of a filter cake during leaching of a sulfur-containing metal concentrate, in which the leach residue is fed the reactor (20) where the injected fluidizing gas to form a fluidized bed, comprising at least part of the leach residue, and wherein the leach residue is heated in the presence of inert particles constituting the particle SiO _2, up to a temperature of 600 to 900 ° C in an oxidizing atmosphere to obtain calcined particles and SO ₂ , which is then used for the production of sulfuric acid, and at least 60 wt.% of inert particles are removed from the fluidized bed through the outlet line (22) to remove inert particles from the fluidized bed, and at least at least 60 wt.% of the burnt particles are recovered together with the gas stream containing waste hectares sludge and fluidizing gas, through the outlet line (21) for fired particles obtained from the leach residue, together with the exhaust gas from the reactor (20), wherein the diameter of at least 70 wt.% of fired particles is less than 60 μm and / or the diameter of at least 70 wt.% of inert particles is from 0.05 to 3 mm, the average residence time of the leach residue in the reactor is from 20 to 200 minutes, the velocity of the fluidizing gas at the inlet is from 0.2 to 2 m / s.

The leach residue from the leaching of a sulfur-containing concentrate, preferably a non-ferrous metal concentrate, is fed to the reactor. There the residue and inert particles are brought into a fluidized state by means of a fluidizing gas which is introduced from at least one nozzle, preferably from a nozzle grid of the reactor. Thus, a fluidized bed is obtained, operating at temperatures from 500 to 900 ° C, preferably from 600 to 900 ° C, most preferably from 650 to 850 ° C, in an oxidizing atmosphere, to obtain fired particles and SO2. After a specified residence time, the calcined particles obtained from the residue

- 1 037686 from leaching, is removed from the reactor after carrying out the appropriate chemical reactions.

Most importantly, the fluidized bed is designed such that at least 60 wt%, preferably 80 wt%, most preferably 90 wt% of inert particles (regardless of the fraction of calcined particles recovered) are recovered from the fluidized bed, while at least 60 wt.%, preferably 80 wt.%, most preferably 90 wt.%, fired particles (regardless of the proportion of inert particles recovered) are recovered together with a gas stream containing off-gases and fluidizing gas. This effect can be achieved through various parameters that are sensitive to the respective minimum rates of liquefaction of inert and calcined particles, such as particle diameters and densities.

Thus, the different particles are separated already in the fluidized bed reactor, with the result that there is no need for additional particle separation. By raising the calcined particles above the level of the fluidized bed, at least a major portion of the calcined particles can be recovered without any additional inert material.

In addition, the above is preferable during operation for the following reason. If all the particles stick together, the agglomerates will have a higher effective particle size, a higher mass, and therefore sink in the fluidized bed. In the lower part of the fluidized bed, inert particles, due to their increased concentration, prevent sintering of already adhered fired particles, as is well known from the methods of the prior art.

In addition, the rise of the fired particles above the fluidized bed results in a more uniform reaction between the oxygen in the fluidizing gas and the sulfur in the residue. This happens because the oxygen concentration is maximum in the inner loop, while the sulfur concentration changes in exactly the opposite trend, that is, it is minimal or equal to zero in the inner loop, is higher in the first zone and the highest in the second zone due to concentration of residue particles. As a result of a more uniform oxidation of sulfur, the formation of local overheating spots, which are the main cause of sintering, is excluded. In the present invention, inert substances, preferably in a particularly high concentration near the bottom, act as some form of insulating layer, while the term inert is used to describe a substance that is usually not reactive during partial firing.

It is preferable that a distinctive feature of the claimed method is two zones located one above the other along the height of the reactors. In this case, at least 60 wt.%, Preferably 80 wt.%, Most preferably 90 wt.% Of inert particles (regardless of the proportion of fired particles) are in the first zone of the fluidized bed, while at least 60 wt.% , preferably 80 wt.%, most preferably 90 wt.% of the residue particles or calcined residue particles (regardless of the proportion of inert particles) are in the second zone located above the first zone. The formation of these two zones occurs during steady-state operation of the reactor and becomes especially evident with a linear decrease in the supply of liquefying gas (during controlled shutdowns or planned shutdowns).

The fines in the first zone are recovered from the fluidized bed, while fines from the second zone are recovered with a gas stream containing off-gases and fluidizing gas. The existence of these different zones can be controlled by different parameters or different densities of the residue and / or inert particles, since the diameters and densities of the particles are sensitive to the respective minimum liquefaction rates. Moreover, the formation of these two zones becomes more evident with a linear decrease in the supply of fluidizing gas to the reactor, which leads to safe, in terms of sintering potential, short or long-term shutdown of the reactor, as explained below.

Additionally, this mode of operation protects the reactor from sintering during planned or unforeseen shutdowns. A gradual decrease in the flow of fluidizing gas leads to more pronounced formation of two zones of fluidization, since the requirements for the reaction are close to the minimum rate of liquefaction of inert particles or do not correspond to it (during a linear decrease in the supply of fluidizing gas), while a rate higher than the corresponding one is still required. minimum rate of liquefaction of residue particles / calcined particles. An additional decrease in the gas supply until the moment when the inert particles no longer liquefy, followed by an abrupt cessation of the fluidizing gas supply, leads to a shutdown, in which the first zone contains the maximum possible amount of inert particles (higher than during steady-state operation), so that during the period when the reactor does not work, sintering cannot take place. Moreover, the possibility of sintering in the reactor at start-up is also minimized in the vicinity of the part of the nozzles directed into the first zone in which the content of inert substances is maximum. Any sintering processes occurring in the second zones are reversible during start-up due to the moment of inertia and the resulting movement in the first zone.

Another embodiment of the present invention consists in the fact that at least 60 wt.%, Preferably 80 wt.%, Most preferably 90 wt.% Of inert particles (regardless of the proportion of fired

- 2,037686 particles) and at least 60 wt.%, Preferably 80 wt.%, Most preferably 90 wt.% Of the leach residue and / or calcined particles (regardless of the proportion of inert particles) are in the common mixing zone. They are preferably uniformly mixed. This achieves a dilution of the residue, as a result of which agglomeration is prevented.

Preferably, the diameter of at least 70 wt%, preferably at least 80 wt% of the fired particles is less than 60 μm, or the diameter of at least 70 wt%, preferably 80 wt% of the inert particles is from 0.05 to 3 mm , preferably 0.1 to 2 mm. Thus, separate extraction is possible. In addition, the latter values are representative of the typical size of the fired SiO ₂ particles in the form of sand, so no further pretreatment is required.

It is particularly cost effective to use SiO ₂ particles as inert particles, since sand is cheap, readily available and easy to handle. In addition, as noted above, SiO2 is also contained in a typical leach residue.

In addition, the preferred technical solution of the claimed invention uses from 0.01 to 1 ton of inert material, preferably sand, per ton of dried leach residue. In this way, it is possible to ensure that the introduced leach residue does not reach the bottom of the reactor, but is burnt in the upper part of the bed and is transported from there in the form of calcined particles by means of an off-gas stream.

In addition, the average residence time of the material supplied as leach residue and recovered as calcined particles is 20 to 200 minutes, preferably 30 to 180 minutes. In this case, you can carry out a full cycle.

The average residence time of the inert particles is several hours, preferably 2 to 10 hours, most preferably 3 to 7 hours, so this solid flow can be kept low.

Preferably, the inlet velocity of the fluidizing gas is 0.2 to 2 m / s, preferably 0.5 to 1.5 m / s. Thanks to this parameter, it is possible that after drying and / or reducing the sulfur content of the fired particles, these particles rise above the second zone into the so-called headspace. From there, the particles can be recovered with the fluidizing gas stream and separated, for example using a cyclone. The liquefaction rate in the sense in which it is understood in this invention, is the rate of the gas phase generated in the furnace under operating conditions compared to the speed in the empty furnace.

The oxidizing atmosphere is preferably controlled so that to ensure a complete cycle, the coefficient λ of excess oxygen in the fuel-oxygen mixture (defined as the ratio of the mass flow of oxygen entering the fluidized bed furnace to the minimum amount of oxygen required to achieve complete stoichiometric combustion of the introduced sulfur-containing residue) is from 1.1 to 1.8, preferably from 1.1 to 1.5, most preferably from 1.3 to 1.5. Thus, it has been proposed to use air or oxygen-enriched air as the fluidizing gas, since air is a cheap source of oxygen required for complete combustion of sulfur. However, nitrogen or any other inert gas can be used as the fluidizing gas, and the gas containing oxygen is introduced separately.

Sulfur residue is usually available as filter cake. In order to uniformly feed such material into the reactor, it is proposed to mix this material with water, preferably using an intensive mixer, to break up lumps or agglomerates. In such a case, the solids content is controlled from 30 to 65 mass% depending on the content of non-combustible substances in the residue.

In addition, it is also possible to mix the leach residue with any inert material, preferably the inert material used in the fluidized bed, most preferably when the material already used in the fluidized bed is also admixed to the residue. In this case, it is possible to form granules and feed the residue into the reactor in the form of more homogenized particles. As a result, it is easier to control fluidization parameters such as the fluidization rate so that most of the fired particles can be recovered with the off-gas stream. In addition, this variant additionally has the advantage of producing more steam from the waste gases, since no water is added to the feed material. As a result, the overall energy balance is improved.

It is also preferable to separate the particles recovered from the fluidized bed into inert and calcined particles in order to be able to recover the valuable metal compounds recovered together with the inert particles.

In the present invention, it is also preferable to use a grinder in this separation step to break up conglomerates of calcined and inert material in order to optimize the process and achieve better separation.

In addition, it is also preferable to separate the particles from the second zone from the exhaust gases so that the particles can be cooled and the energy consumption of the process can be improved by recovering at least a portion of the energy of the particles. Exhaust gases are sent to the afterburner, to the boiler for cleaning the grief

- 3 037686 sneeze gases, as well as to the stage of wet gas cleaning.

As already mentioned, the energy balance of the method can be optimized by recuperating the energy obtained by cooling the inert particles, as well as by cooling the fired particles. In this case, the inert and / or calcined particles are cooled by preheating the gas stream, and the preheated gas stream is recycled to the process step preceding the reactor, preferably to the pellet mixer and / or to the reactor itself. Most preferably, cooling of the inert and / or calcined particles can be used to preheat the fluidizing gas and / or the oxygen source.

In addition, this invention relates to the use of a device, the distinctive features of which are given in claim 11 of the claims.

The use of a device for the disposal of a leach residue containing from 30 to 60 wt% elemental sulfur, obtained in the form of a filter cake when leaching a sulfur-containing concentrate of non-ferrous metals, by the method according to any one of claims 1-10, includes the use of a device that contains a container (10 ) for mixing to form a slurry or granules from the residues, a reactor (20) with at least one line (13) for supplying the slurry or a line (19) for feeding granules for treating the leach residue obtained in the form of a filter cake during leaching of sulfur-containing concentrate of non-ferrous metals, into the reactor (20), the supply line (23) for supplying the fluidizing gas to the reactor (20), at least one outlet line (21) for extracting the calcined particles obtained from the leach residue, together with the exhaust gas from the reactor (20) into the cyclone (30) and the outlet pipeline (22) for extracting inert particles from the fluidized bed, in which the outlet pipe The gadfly (22) is located so that at least 60 wt.% of inert particles are removed through said outlet pipeline (22), characterized in that the first cooler (50b) is connected to the outlet pipeline (22) for inert particles, and the second cooler ( 50a) is connected to a cyclone (30), while the fired particles are separated from the exhaust gas.

Such a device for treating the leach residue formed during the leaching of sulfur-containing concentrates, preferably non-ferrous metal concentrates, includes a mixing vessel for producing a slurry from said residues. Alternatively, the leach residue is co-treated with inert material / sand in a high intensity mixer to form granules. In addition, it includes a reactor in which a fluidized bed is formed during operation.

The features of the reactor are at least one feed pipe for supplying the residue to the reactor with at least one pipe for feeding into the reactor the leach residue obtained by leaching the sulfur-containing non-ferrous metal concentrate;

a pipeline for supplying a fluidizing gas to the reactor;

at least one outlet line for recovering calcined particles obtained from the leach residue together with the reactor effluent gas and with an outlet line for recovering inert particles from the fluidized bed, said outlet line being located so that at least 60 wt.% inert particles are removed through this outlet line.

With this design, agglomeration in the reactor is avoided, and the fired particles are recovered without substantial mixing with the inert particles, preferably at least 10 wt% of the inert particles are entrained in the exhaust gas together with the fired particles. In addition, the device according to the invention is provided with at least one feeding device for transferring the slurry or granules into the reactor.

In one preferred embodiment of the present invention, the fluidizing gas is fed into a fluidized bed reactor in a so-called nozzle grid, that is, a plate containing nozzles with a density of 1 to 300 holes per square meter of furnace area. There are several types of nozzles, including the following:

(i) not protruding from the nozzle array and having one opening directed upward;

(ii) protruding from the barrel of the nozzles having one or more holes located at an angle of 0 to 180 °; and (iii) nozzles of the same design as in the latter case, having as an additional feature a cap for additional protection against clogging of the holes.

Preferably, the device is also characterized by having a first cooler connected to the inert particle outlet and a second cooler connected to a cyclone in which the burnt particles are separated from the exhaust gas for separate treatment of both types of particles.

Additional developments, advantages and possible applications of the present invention can also be understood from the following description of the drawings. All features described and / or illustrated form the subject of this invention by themselves or in any combination, regardless of whether they are included in the claims or where they are referred to.

FIG. 1 is a schematic representation of a process according to the invention using a suspension.

FIG. 2 is a schematic representation of the method according to the invention using granules.

- 4 037686

FIG. 1 shows a slurry vessel 10, which is filled through line 11 with sulfur-containing residue from the direct leaching process. Sulfur residue is most often available as filter cake. This material is mixed with the water supplied through line 12 using an intensive mixer to break up lumps and agglomerates. The solids content is adjusted from 30 to 65% by weight, depending on the incombustible content of the sulfur-containing residue.

The slurry is introduced into the fluidized bed reactor 20 via line 13. The fluidized bed reactor 20 contains a bed of fluidized sand. The sand serves two purposes, namely, firstly, it provides a stable bed of fluidized solids, into which the sulfur-containing residue can be introduced and in which all reactions should take place, and, secondly, it prevents the sintering of non-combustible substances by separating the individual PbSO ₄ / PbO grains.

The fluidized sand bed in the fluidized bed reactor 20 contains non-combustible compounds from the introduced sulfur-containing residue, mainly in the upper part of the bed, and the lower part is largely depleted in non-combustible substances. The combustion / calcination process is carried out in such a way that the injected slurry is uniformly distributed over the fluidized sand bed. Most of the introduced material does not reach the bottom of the furnace, but burns off at the top of the bed. The fluidization rate is controlled so that most of the very fine particles of non-combustible substances (x ₈₀ << 40 μm) are carried away by the process gas and leave the furnace together with the exhaust gas through the outlet line 21.

A minority of non-combustible substances form agglomerates and are discharged with some sand through an outlet line 22, such as, for example, an overflow device, as this is common practice in the firing of zinc concentrates and pyrite.

The other part of non-combustible substances forms relatively large agglomerates (> 1 mm), accumulating at the bottom of the fluidized bed. This material is discharged every few hours through an outlet not shown in the drawing in the bottom of the reactor.

In a fluidized bed reactor, different separation of inert and fired particles is achieved due to different positions of the extraction points by appropriate regulation of the proportion of sand (from 0.01 to 1 ton in relation to the dried sulfur-containing residue), the size of sand particles (from 0.1 to 2 mm ) and liquefaction speed (from 0.5 to 1.5 m / s) in combination with the use of discharge during continuous operation, as well as fine sorting of non-combustible substances (x ₈₀ << 40 μm), which is inherent in this method.

The stream of calcined particles and off-gas is directed through the outlet line 21 to the cyclone 30, in which the gas stream is separated from the calcined particles. The separated particles are directed through conduit 32 to a cooler 50a, for example a cooling drum. Gas is supplied to the cooler as a heat carrier through line 51. The cooled content discharged from the cyclone is directed through line 52 to line 57.

The off-gas stream, containing mainly non-combustible substances together with fine sand particles, is directed further through the pipeline 31 to the afterburner chamber 33 to oxidize the sulfur vapor with additional air or any oxygen-containing gas. The resulting dust is directed through line 36 to a collection line 57.

The off-gas is then directed through the line 34 to the recuperator boiler 40 for heat recovery by generating steam. The solids separated in the recuperator boiler are also combined via line 48 with all product streams in line 57. In specific cases, for example, if the capacity of the unit in question is too low, the recuperator boiler 40 can be replaced with an evaporative cooler.

By moving downstream of the gas channel, the solids are fed through line 41 to a standard hot gas purification system 42. Gas 44 in the hot gas scrubbing system is also used to produce sulfuric acid after it has been scrubbed in a standard gas scrubber system 45.

Particles 43 separated in the hot gas scrubbing system can also be mixed through lines 47 and 48 with the total product stream in line 57. However, in the case where this solids stream (or any other solid stream) still contains a significant amount of sulfide sulfur , this stream is recycled, preferably to the slurry vessel, via line 43. In addition, even if not shown, it is possible to recycle the stream of solids to the reactor 20. In addition, not shown, it is possible to arrange recirculation lines from the chamber 33 afterburning and / or from the boiler 40.

Inert particles recovered from the fluidized bed of the fluidized bed reactor 20 are fed to a cooler 50b, where they are also cooled with air or any other gas. This hot gas stream can be used as fluidizing gas and fed through line 24 to the fluidized bed reactor through line 23. Both coolers can be designed as cooling sections and use the same heating medium. In addition, even if not shown, it is possible to have separate heating medium lines in both cooling sections.

- 5 037686

The cooled sand can be sent to an optional grinder and separation unit 55 through conduit 54 where metallurgical particles are separated from the sand. Metallurgical particles are collected in line 57, which will be fed to all other product lines.

Sand or any other inert particles can be recycled to the fluidized bed reactor 20 directly through conduit 56.

FIG. 2 shows an almost identical method. The only difference is that granules rather than slurry are fed into the fluidized bed reactor 20. This option has the advantage that more steam is produced since no water is added to the raw material. The viscous cake from the sulfur-containing filter cake must be crushed to provide a controlled feed to the furnace 20. This is achieved by mixing the sulfur-containing cake with sand in mixer 14, preferably a high shear mixer. Sulfur residue is fed to the mixer via line 11 and additional sand is fed via line 15. It has been found that 1.5 to 4 tonnes of sand per tonne of dried sulphide residue is required to obtain a highly free-flowing feed mixture. The sand grain size is preferably 0.1 to 1 mm. Vigorous stirring results in granules of acceptable grain size for fluidized bed calcination (with the bulk of solids ranging from 300 to 600 microns, while solids ranging from 0.1 to 3 mm will still be present).

Before being fed to the fluidized bed reactor 20, the granules pass through line 16 to an optional drier 17 to increase their stability. The removed water is withdrawn through line 18. The dryer 17 can use preheated air, which is passed directly or indirectly to another stage of the method and / or into water or other liquid, preheated using a heat source included in this method or additional with respect to him. In addition, the dryer 17 can also be electrically heated or designed as a fluidized bed. The need for a drying step depends on the properties of the sulfur-containing residue. It is possible that sulfur-containing residues will not need to be dried at all before firing.

This combustion / calcination method in the fluidized bed reactor 20 differs from the method in FIG. 1 in that the entire bed volume of the fluidized bed reactor 20 is used for the combustion / calcination process. Sintering is achieved through optimal separation of sticky particles (sulphates and lead oxides) in the sand matrix. Combustion takes place at 650-850 ° C with a λ coefficient of 1.1 to 1.5, as in the method in FIG. 1. In equilibrium, the fluidized bed reactor 20 is under heat, and carbonaceous fuel can be fired in the fluidized bed reactor 20 to maintain the desired operating temperature. This is also possible for the method in FIG. 1. However, for this method to be attractive, it must be self-sustaining.

The liquefaction speed is in the typical stable firing range of 0.5 to 1.5 m / s. The main portion of the calcined substance is discharged through an outlet overflow device. Fine sand particles and burnt particles are carried away by the flue gas of the kiln. The fluidized bed reactor 20 has an outlet at the bottom for internal discharge or possible large agglomerates. The calcined materials discharged from the fluidized bed reactor 20 are cooled in a cooling drum 50 (a, b). The separation of sand and silver-containing valuable components is achieved by treatment in a grinding step followed by sorting by sieving or air separation.

The off-gas contains mainly non-combustible substances together with some small proportion of sand. It should be noted that the particulate matter contains most of the silver, as well as lead sulphates / oxides, zinc sulphates / oxides, iron, mainly in the form of hematite, and silicon oxide, and must be sold and further processed in a lead smelter.

In an additional process step, pure sulfur can be separated from the sulfur-containing residue by means of a vacuum distillation step, which is carried out using steam generated in a recuperator at 250-300 ° C. Such manner noncombustible fraction enriched to 60 wt.%, And it exists in the form of very small (x8 ₀ << 40 microns) solids suspended in the liquid sulfur phase. This sulfur phase is atomized to fine particles (x ₈₀ <80 μm) and can be used for combustion as shown in both figures. The vaporized sulfur is condensed in a bath of liquid sulfur at a temperature slightly below the vaporization temperature of the sulfur. Thus, evaporated impurities such as mercury remain in the gas phase and can be separated from the sulfur. The off-gas is further purified in prior art purification steps. Condensed sulfur is pure elemental sulfur and can be sold as a product.

The sand (or any other inert particles) recovered in the grinder and separation unit is at least partially recycled through line 61 to the mixer to form granules. However, at least a portion of these particles can also be recycled to the fluidized bed reactor 20.

Preheated air (or any other gas) from at least one cooler 50a, 50b is fed, at least partially, through lines 62, 63 to dryer 17, where they are used

- 6 037686 for drying and / or preheating pellets.

Additionally, at least a portion of the preheated gas from at least one cooler 50a, 50b is fed via lines 62 and 64 to a fluidized bed reactor 20 where it can be used as a fluidizing gas and / or an oxygen source.

List of numbered references

- mixer,

11-13 - pipeline,

- mixer,, 16 - pipeline,

- dryer, 19 - pipeline,

- fluidized bed reactor,

- outlet pipeline,

- outlet pipeline, 24 - pipeline,

- cyclone,, 32 - pipeline,

- afterburning stage,

34-36 - pipeline,

- boiler,

- pipeline

- hot gas cleaning, 44 - pipeline,

- wet gas cleaning,

46-48 - pipeline,

50a, 50b - cooler,

51-54 - pipeline,

- grinder and separation unit,, 57 - pipeline,

61-64 - pipeline.

Claims (11)

CLAIM 1. Method of utilization of leach residue containing from 30 to 60 wt% elemental sulfur, obtained in the form of filter cake during leaching of sulfur-containing metal concentrate, in which the leach residue is fed into reactor (20), where fluidizing gas is introduced to form a fluidized bed comprising at least part of the leach residue, and wherein the leach residue is heated in the presence of inert particles constituting the particle SiO _2, up to a temperature of 600 to 900 ° C in an oxidizing atmosphere to obtain a fired particles and SO2, which is then used for sulfuric acid production, wherein at least 60 wt.% of inert particles are recovered from the fluidized bed through an outlet conduit (22) to recover inert particles from the fluidized bed, and at least 60 wt.% of fired particles are recovered together with a gas stream containing waste gases and fluidizing gas, through the discharge line (21) for the fired particles obtained from the leach residue, together with the exhaust gas from the reactor (20), wherein the diameter of at least 70 wt.% of the calcined particles is less than 60 μm and / or the diameter of at least 70 wt.% of the inert particles is from 0.05 to 3 mm, the average residence time of the leach residue in the reactor is from 20 to 200 minutes and the velocity of the fluidizing gas at the inlet is from 0.2 to 2 m / s. 2. The method according to claim 1, characterized in that at least 60 wt.% Of the inert particles form the first zone of the fluidized bed, and at least 60 wt.% Of the leach residue and / or calcined particles are in the second zone located above the first zone. 3. The method according to claim 2, characterized in that before feeding into the reactor, the leach residue is mixed with water to obtain a slurry, or in that, before feeding into the reactor, the leach residue is mixed with inert material and / or material from the first zone. 4. A method according to claim 2 or 3, characterized in that the particles removed from the first zone are separated into inert particles and calcined particles. 5. A method according to any one of claims 2 to 4, characterized in that the particles recovered from the second zone are separated from the exhaust gas. 6. A method according to claim 1, wherein the fluidized bed comprises a mixed zone containing at least 60% by weight of inert particles and at least 60% by weight of leach residue and / or fired particles as a mixture. - 7 037686 7. A method according to any one of the preceding claims, characterized in that the ratio of inert material per ton of dried leach residue is set in the range from 0.01 to 1 ton. 8. A method according to any of the preceding claims, characterized in that the oxidizing atmosphere is controlled such that the lambda coefficient of the excess oxygen in the fuel-oxygen mixture is between 1.1 and 1.8. 9. A method according to claim 8, characterized in that the dust contained in the exhaust gas is recycled to a process step carried out in a mixing vessel (10) located upstream of the reactor and / or in the reactor. 10. A method according to any of the preceding claims, characterized in that the inert and / or calcined particles are cooled by preheating the gas stream, the preheated gas stream being recycled to the reactor. 11. The use of a device for disposal containing from 30 to 60 wt.% Of elemental sulfur of the leach residue obtained in the form of a cake on the filter when leaching sulfur-containing concentrate of non-ferrous metals, by the method according to any one of claims 1-10, where the device contains a container (10 ) for mixing to form a slurry or granules from the residues, a reactor (20) with at least one line (13) for supplying the slurry or a line (19) for feeding granules for treating the leach residue obtained in the form of a filter cake during leaching of sulfur-containing concentrate of non-ferrous metals, into the reactor (20), the supply line (23) for supplying the fluidizing gas to the reactor (20), at least one outlet line (21) for extracting the calcined particles obtained from the leach residue, together with the exhaust gas from the reactor (20) into the cyclone (30) and the outlet line (22) for removing inert particles from the fluidized bed, in which the outlet line (22) is located so that at least 60 wt.% of inert particles is removed through said outlet line (22), characterized in that the first cooler (50b) is connected to the outlet line (22) for inert particles, and the second cooler (50a) is connected to the cyclone (30), while the calcined particles are separated from the exhaust gas.