DE102020200602A1 - Thermal treatment of mineral raw materials with a mechanical fluidized bed reactor - Google Patents

Abstract

The present invention relates to a device for the thermal treatment of mineral raw materials, in particular lithium ores, the device having a comminution device 10, a granulation device 30 and a heat treatment device, characterized in that the granulation device 30 is a mechanical fluidized bed reactor.

Description

The invention relates to an apparatus and a method in particular for lithium ores.

From the U.S. 6,083,295 A a method for processing fine-grained material with granulation is known.

From the WO 2017/144469 A1 a method for the heat treatment of granular solids is known.

From the DE 27 26 138 A1 a method and a device for the production of cement clinker from moist agglomerated cement raw material is known. The device has a preheating zone, a deacidification zone and a sintering zone.

From the DE 10 2017 202 824 A1 a plant for the production of cement, in particular cement clinker, with a preheater which has a plurality of cyclones, a calciner for deacidification and a rotary kiln is known.

From the EP 3 476 812 A1 a method for drying granulated material is known.

From the EP 0 500 561 B1 a device for mixing and thermal treatment of solid particles with a substantially horizontally arranged container is known. From the DE 1 051 250 a method and a device for mixing powdery or fine-grained masses with liquids are known. From the DE 27 29 477 C2 a ploughshare-like mixing tool for such devices is known. A similar mixing tool for such devices is also from DE 197 06 364 C2 famous. Corresponding mixing devices are offered by Gebrüder Lödige Maschinenbau GmbH under the name PflugscharMischer and generate a mechanical fluidized bed inside.

The object of the invention is to provide a device and a method with which, above all, ores can be thermally treated, which on the one hand tend to build up more deposits and on the other hand can represent an increased load on the air circuit due to melting properties and / or particle sizes.

This object is achieved by the device with the features specified in claim 1 and the method with the features specified in claim 11. Advantageous further developments result from the subclaims, the following description and the drawings.

The device according to the invention for the thermal treatment of mineral raw materials is used in particular for the thermal treatment of lithium ores, for example lithium aluminum silicate such as spodumene (LiAl [Si ₂ O ₆ ]) or petalite (LiAl [Si ₄ O ₁₀ ]).

The device has a comminution device, a granulation device and a heat treatment device. According to the invention, the granulation device is a mechanical fluidized bed reactor.

It has been shown that a mechanical fluidized bed reactor in particular leads to a very advantageous change in the finely ground mineral raw material. The comparatively uniform size distribution of the agglomerated particles prevents both sticking in a heat treatment device and the transition of the product into the gas phase. The latter means that the product has to be filtered out of the exhaust gas flow and is thus practically circulated, which is a burden for the entire process.

While gases are used in a normal fluidized bed reactor to mix a solid with the gas space and thus fluidize and transport it, in a mechanical fluidized bed reactor this is achieved purely mechanically with the help of a mixing tool.

It has been shown that the effect of the mechanical fluidized bed reactor is that the very fine particles, which are ground, agglomerate. This avoids the formation of dust in the following process steps, since particularly small particles in particular can be reduced very significantly. As a result, there is also significantly less material sticking to the walls of the preheater, in particular if it is designed in the form of several cyclones arranged one after the other.

The preheater can be designed as a direct current preheater. Here, gas and solid are transported in the same direction, while the heat is transferred from the gas to the solid. An example of this are cyclones connected in series. The heat transfer takes place in the connections between the cyclones in cocurrent, the cyclones then serve to separate gas and solids.

Alternatively, the preheater can be designed as a countercurrent preheater. A corresponding preheater is for example and in particular from DE 383 42 15 A1 famous.

In a further embodiment of the invention, the heat treatment device has a preheater, the preheater having 2 to 8 cyclones. Cyclones allow the material to be heated quickly and efficiently. At the same time, the gas is cooled in countercurrent and the energy is recovered.

In a further embodiment of the invention, the heat treatment device has a calciner.

In a further embodiment of the invention, the calciner is a multi-deck furnace.

In a further embodiment of the invention, a cooler is arranged next to the heat treatment device. By way of example and preferably, the cooler consists of 2 to 8 cyclones. Cyclones allow the material to be cooled down quickly and efficiently. At the same time, the gas is heated in countercurrent.

In a further embodiment of the invention, the cooler is connected directly to the calciner. In this embodiment, a furnace, in particular a rotary kiln, is thus completely dispensed with. This significantly reduces the dwell time in the entire device and lowers the energy requirement. However, this requires rapid and uniform heating and thus material conversion, which is given by the equalizing effect of the mechanical fluidized bed. By using the mechanical fluidized bed reactor, it has been found that extremely uniform agglomeration of the starting material is achieved. This leads to the fact that, in addition to the excellent adhesion-free passage through the preheater and the calciner, there is also extremely good and, above all, even heating and thus conversion of the starting material. It has been shown that the starting material has already been converted after it has passed through the calciner. As a result, the long heating in the oven, which according to the prevailing opinion is necessary for complete implementation, can be dispensed with. This results in savings both in the construction of the system and, above all, in its operation.

In an alternative embodiment of the invention, the heat treatment device has a rotary kiln. This embodiment can be preferred if a longer thermal treatment of the starting material leads to optimized product properties.

In a further embodiment of the invention, the mechanical fluidized bed reactor has an essentially horizontally arranged container. A shaft is arranged centrally along the longitudinal axis of the container, with mixing tools being arranged radially on the shaft. In the simplest case, these mixing tools can be arranged in the form of a rod and vertically on the shaft. The mixing tools are particularly preferably designed in the shape of a ploughshare. Examples of ploughshare-shaped mixing tools can, for example, be the DE 27 29 477 C2 or the DE 197 06 364 C2 can be removed.

In a further embodiment of the invention, the mechanical fluidized bed reactor has at least one fluid supply. Further fluid feeds can also be arranged, in particular along the direction of transport of the material. The fluid supply is particularly preferably used to supply water. Water supports the agglomeration and thus leads to more uniform particles. In particular, the addition of water reduces the proportion of the smallest particles, which means that dust formation and material sticking in the cyclones can be avoided particularly efficiently.

In a further embodiment of the invention, a fluid feed is arranged upstream of the mechanical fluidized bed reactor. This can be present in addition or as an alternative to a fluid supply in the mechanical fluidized bed reactor.

In a further embodiment of the invention, the mechanical fluidized bed reactor has a fuel feed. Alternatively or additionally, fuel can also be fed in upstream of the mechanical fluidized bed reactor. This allows the fuel to be incorporated into the particles formed by agglomeration in the mechanical fluidized bed reactor. This fuel ignites in a later process after its ignition temperature is exceeded, for example in the calciner, and thus leads to a much more targeted heating of the raw material.

In a further embodiment of the invention, a rising tube dryer is arranged between the mechanical fluidized bed reactor and the preheater. The riser dryer has two advantages. On the one hand, in particular water, which is used in the agglomeration in the mechanical fluidized bed reactor, can be discharged. On the other hand, the material can be transported to the entrance height of the preheater. The riser dryer can also be used to adjust the particle size. Particles that are too large can in particular be separated off and, in particular, returned for re-grinding via the gas velocity and, if necessary, via a separating cyclone at the upper end of the riser dryer.

In a further embodiment of the invention, a homogenization stage is arranged between the comminution device and the mechanical fluidized bed reactor. A homogenization stage is particularly advantageous if fuel and / or binding agent is added before the homogenization stage.

In a further embodiment of the invention, a rising tube dryer is arranged between the mechanical fluidized bed reactor and the heat treatment device. The riser dryer has two advantages. On the one hand, in particular water which is used in the agglomeration in the mechanical fluidized bed reactor can be discharged. On the other hand, the material can be transported to the entrance height of the preheater.

1. a) Zerkleinern des mineralischen Rohstoffes in einer Zerkleinerungsvorrichtung,
2. b) Granulieren des Produkts aus Schritt a) in einer Granulationsvorrichtung,
3. c) Wärmebehandlung des Produktes aus Schritt b) in einer Wärmebehandlungsvorrichtung.

Das Verfahren zeichnet sich erfindungsgemäß dadurch aus, dass nach Schritt b) 90 % aller Partikel eine Partikelgröße zwischen 500 µm und 5 mm aufweisen.In a further aspect, the invention relates to a method for the thermal treatment of mineral raw materials, in particular lithium ores, the method having the following steps:

1. a) comminution of the mineral raw material in a comminution device,
2. b) granulating the product from step a) in a granulating device,
3. c) Heat treatment of the product from step b) in a heat treatment device.

According to the invention, the method is characterized in that after step b) 90% of all particles have a particle size between 500 μm and 5 mm.

In this way, the starting material can advantageously be ground very finely. Usually a compromise has to be made. The finer the materials are ground, the better and more homogeneous the firing process is. However, particles that are too small are disruptive to the process, as already explained. However, since the particles are not introduced into the process in the finely ground size, this limitation does not apply.

In a further embodiment of the invention, a mechanical fluidized bed reactor is selected as the granulation device.

In a further embodiment of the invention, a granulating plate is selected as the granulating device.

In a further embodiment of the invention, a material bed roller mill is selected as the granulation device.

In a further embodiment of the invention, a bricket press is selected as the granulation device.

In a further embodiment of the invention, a fuel, in particular a fuel with an ignition temperature of 500.degree. C. to 650.degree. C., is added before and / or in step b). The fuel is preferably selected from the group comprising coal, coal dust and cellulose.

This fuel ignites in a later process after its ignition temperature is exceeded, for example in the calciner, and thus leads to a much more targeted heating of the raw material.

In a further embodiment of the invention, fuel is supplied up to a mass content of at most 50%, preferably of at most 20%.

In a further embodiment of the invention, fuel is supplied up to a mass content of at least 0.1%, preferably of at least 5%.

In a further embodiment of the invention, a binder is added before and / or in step b). By way of example and with preference, aluminum silicate or a sulfate is selected as the binder.

In a further embodiment of the invention, the heat treatment in step c) is carried out at a temperature of at least 600.degree. C., preferably at least 800.degree.

In a further embodiment of the invention, the heat treatment in step c) is carried out at a temperature of at most 1200.degree. C., preferably at most 1100.degree. C., particularly preferably at most 1000.degree.

In a further embodiment of the invention, the product is cooled after step c), the product preferably being cooled to below 600.degree.

In a further embodiment of the invention, the product is comminuted after step c).

In a further embodiment of the invention, wet grinding takes place in step a) and subsequent agglomeration in step b) without prior drying.

In a further embodiment of the invention carried out in such a way that the nitrogen content of the gas phase in the preheater is less than 30% by volume, preferably less than 15% by volume, particularly is preferably less than 5% by volume. This is preferably achieved by adding pure oxygen as secondary air to the burners. The advantage is that a subsequent separation of the resulting carbon dioxide from the gas phase is facilitated. This is advantageous with the agglomeration of the starting material, since dusts interfere with the deposition of the carbon dioxide. Dusts are, however, particularly greatly reduced by the method according to the invention. The separation of the carbon dioxide serves to avoid the emission of climate-damaging gases.

• 1 erste Ausführungsform
• 2 zweite Ausführungsform

The device according to the invention is explained in more detail below using an exemplary embodiment shown in the drawings.

• 1 first embodiment
• 2 second embodiment

In 1 a first embodiment of a device for the thermal treatment of mineral raw materials is shown. The device has a comminuting device 10 , for example a grinder. This is followed by a homogenization stage 20th arranged, in which the ground mineral raw material is mixed with a fuel and a binder. The starting material is then placed in the granulation device 30th , a mechanical fluidized bed reactor. The granulated material is placed in a riser dryer 40 conveyed and in a preheater 50 transported, which preferably consists of four to six cyclones. To the preheater 50 the calciner closes 60 and to the calciner 60 the rotary kiln 70 on. Preheater 50 , Calcinator 60 and rotary kiln 70 constitute the heat treatment device. The cooler is attached to the heat treatment device 80 on

From the first embodiment, the in 2 Second embodiment shown in that the heat treatment device does not have a rotary kiln 70 has, but the cooler 80 directly to the calciner 60 connects. The calciner is used to generate the heat 60 with a burner 90 connected. The cooler 80 in this second embodiment is preferably made up of four to six cyclones.

List of reference symbols

10

Shredding device

20th

Homogenization stage

30th

Granulation device

40

Riser dryer

50

Preheater

60

Calciner

70

Rotary kiln

80

cooler

90

burner

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• US 6083295 A [0002]
• WO 2017/144469 A1 [0003]
• DE 2726138 A1 [0004]
• DE 102017202824 A1 [0005]
• EP 3476812 A1 [0006]
• EP 0500561 B1 [0007]
• DE 1051250 [0007]
• DE 2729477 C2 [0007, 0023]
• DE 19706364 C2 [0007, 0023]
• DE 3834215 A1 [0016]

Claims (22)

Device for the thermal treatment of mineral raw materials, in particular lithium ores, the device having a comminution device (10), a granulation device (30) and a heat treatment device, characterized in that the granulation device (30) is a mechanical fluidized bed reactor. Device according to Claim 1 , characterized in that the heat treatment device has a preheater (50), the preheater (50) having 2 to 8 cyclones. Device according to one of the preceding claims, characterized in that the heat treatment device has a calciner (60). Device according to one of the preceding claims, characterized in that a cooler (80) is arranged next to the heat treatment device. Device according to Claim 3 and Claim 4 , characterized in that the cooler (80) is connected directly to the calciner (60). Device according to one of the Claims 1 until 4th , characterized in that the heat treatment device has a rotary kiln (70). Device according to one of the preceding claims, characterized in that the mechanical fluidized bed reactor has an essentially horizontally arranged container, a shaft being arranged centrally along the longitudinal axis of the container, mixing tools being arranged radially on the shaft. Device according to Claim 7 , characterized in that the mixing tools are designed in the shape of a ploughshare. Device according to one of the preceding claims, characterized in that a homogenization stage (20) is arranged between the comminution device (10) and the mechanical fluidized bed reactor. Device according to one of the preceding claims, characterized in that a rising tube dryer (40) is arranged between the mechanical fluidized bed reactor and the heat treatment device. A method for the thermal treatment of mineral raw materials, in particular lithium ores, the method comprising the following steps: a) comminuting the mineral raw material in a comminution device (10), b) granulating the product from step a) in a granulation device (30), c) Heat treatment of the product from step b) in a heat treatment device, characterized in that after step b) 90% of all particles have a particle size between 500 µm and 5 mm. Procedure according to Claim 11 , characterized in that a mechanical fluidized bed reactor is used as the granulation device (30). Method according to one of the Claims 11 until 12th , characterized in that before and / or in step b) a fuel, in particular a fuel with an ignition temperature of 500 ° C to 650 ° C, is added. Procedure according to Claim 13 , characterized in that the fuel is selected from the group comprising coal, coal dust, cellulose. Method according to one of the Claims 13 until 14th , characterized in that fuel is supplied up to a mass content of at most 50%, preferably of at most 20%. Method according to one of the Claims 13 until 15th , characterized in that fuel is supplied up to a mass content of at least 0.1%, preferably of at least 5%. Method according to one of the Claims 11 until 15th , characterized in that a binder is added before and / or in step b). Procedure according to Claim 14 , characterized in that aluminum silicate or a sulfate is selected as the binder. Method according to one of the Claims 11 until 16 , characterized in that the heat treatment in step c) is carried out at a temperature of at least 600 ° C, preferably at least 800 ° C. Method according to one of the Claims 11 until 19th , characterized in that the heat treatment in step c) is carried out at a temperature of not more than 1200 ° C, preferably not more than 1100 ° C, particularly preferably not more than 1000 ° C. Method according to one of the Claims 11 until 20th , characterized in that after step c) the product is cooled. Method according to one of the Claims 11 until 21 , characterized in that after step c) a comminution of the product is carried out.

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