Color optimization device for activating clay

Abstract

The invention relates to a device for the thermal activation of mineral materials, said device comprising a calcining furnace 40, a reduction device and a material cooler 70, said calcining furnace 40 being connected to the reduction device for conveying calcined materials, said reduction device being connected to the material cooler 70 for conveying color-optimized materials, characterized in that the reduction device is connected to the material cooler 70 for conveying the color-optimized materials. The reduction device is a fluidized bed reactor 50.

Description

[0001] The present invention relates to an apparatus and a method for color optimization of activated clay.

[0002] The cement industry is a major source of carbon dioxide emissions. An important issue is the release of carbon dioxide from limestone. To reduce carbon dioxide emissions, alternative clinkers that preferably do not release carbon monoxide during the activation process are used. Thus, activated clay has become an important product. However, a problem with clay is that they usually contain, for example, iron, which is usually oxidized (at least partially) when activated under oxidative conditions and exhibits a strong red color in the form of Fe III However, customers generally do not accept this color. To obtain a color similar to cement or clinker that is acceptable to customers, the activated clay is usually treated under reducing conditions in order to reduce the iron oxide, thereby giving the activated clay a color similar to cement.

[0003] DE 102016104738 A1 discloses a heat treatment method and apparatus for particulate solids.

[0004] DE 102008020600 B4 discloses a method and apparatus for heat treatment of fine-grained mineral solids.

[0005] DE 102011014498 A1 discloses an alternative clinker.

[0006] US2012 / 160135 A1 discloses a method for producing synthetic pozzolan.

[0007] WO 2021 / 224055 A1 discloses a method for color optimization during the production of activated clay.

[0008] US2014 / 0000491 A1 discloses an alternative clinker based on calcined clay.

[0009] DE 102020211750 A1 discloses an energy recovery method during the cooling of color-optimized activated clay.

[0010] US 4573908 A discloses a method and apparatus for producing white cement clinker.

[0011] However, two problems are encountered during the color optimization process. On the one hand, the long residence time of the activated clay at high temperature is disadvantageous as it may lead to deactivation. This effect also depends on the particle size. The smaller the particles, the faster the deactivation rate. On the other hand, decolorization and color optimization also depend on the particle size. The smaller the particles, the more rapid the decolorization, while the larger the particles, the longer the time required for decolorization. Therefore, it is necessary to find an optimum point at which the smallest particles do not deactivate while the largest particles are still able to decolorize.

[0012] This optimum point is achieved by selecting particles with the narrowest possible particle size distribution range, i.e., minimizing the difference between the smallest and the largest particles. However, this method is costly and energy-intensive, and due to the limited application of renewable energy in the production process with a narrow particle size range, this may become a new source of carbon dioxide emissions.

[0013] The object of the present invention is to provide a device and a method enabling color optimization even in the case of a significantly wider particle size distribution.

[0014] This object is achieved by a device having the features described in claim 1. Further advantageous developments can be seen in the dependent claims, the following description, and the drawings.

[0015] The device of the present invention is used for the thermal activation of mineral materials, especially clay. The device includes a calcination furnace, a reduction device, and a material cooler. The calcination furnace and the reduction device are interconnected by a first connector for transporting the calcined material. The reduction device is connected to the material cooler via at least one second connector for transporting the color-optimized material. According to the present invention, the reduction device is a fluidized bed reactor. It has been found that when the particle size distribution is wide (i.e., the particle size range is large), the fluidized bed reactor is extremely advantageous as a reduction device. On the one hand, the extremely small particles can be rapidly extracted by the fluidizing gas. On the other hand, the particle size also affects the transport speed in the fluidized bed reactor. Therefore, the fluidized bed reactor can directly achieve color optimization because the small particles with a faster color optimization rate will be discharged more quickly, while the large particles that require a longer treatment time will have a longer residence time. Thus, significant energy savings are achieved in the processes of particle size reduction and classification of the particle size distribution.

[0016] In addition, a preheater can be arranged, for example, upstream of the calcination furnace. In this way, the heat extracted from the calcination furnace by the gas flow is transferred to the material to be thermally activated.

[0017] According to the present invention, the reduction device includes a first material outlet and a second material outlet. In particular, the first material outlet and the second material outlet are arranged at different heights. For example, the first material outlet may be arranged on the lower side of the fluidized bed. Through the first material outlet, the color-optimized material of the coarse particles can be extracted. For example, the second material outlet may be arranged on the upper side of the fluidized bed. Through the second material outlet, the color-optimized material of the fine particles can be extracted. In this way, in addition to controllable color optimization, separation according to particle size can be achieved synchronously. These two parts of materials can then be optionally processed separately or mixed.

[0018] According to the present invention, the reduction device includes a gas outlet. The gas outlet is connected to the gas purification device through a fourth connector, for example, preferably a filtration device. In the gas purification device, the finest particles of the material after activation and color optimization will settle down. This part of the material is usually also the most active part. It can be selectively recombined with the further activated and color-optimized material. However, this finest particle can also be further processed separately, for example, to meet the needs of particularly high-end applications.

[0019] According to the present invention, the gas purification device includes a solid outlet. The material cooler includes at least a first feed port for cooling the material, a second feed port for cooling the material, an outlet for cooling the material, a cooling gas inlet, and a cooling gas outlet. The position of the first feed port for cooling the material is closer to the cooling gas inlet than the second feed port. The solid outlet is connected to the first feed port for cooling the material through a third connector for transporting the material settled in the gas purification device. The first material outlet and / or the second material outlet are connected to the second feed port for cooling the material through a second connector for transporting the color-optimized material.

[0020] In this way, the fine-grained material from the gas purification device will come into contact with the cooling gas in the cooler, thus being quickly cooled. This is advantageous because the fine particles from the gas purification device are most prone to re-oxidation and therefore should be preferentially cooled particularly quickly.

[0021] The two parts of particles from the reduction device can be optionally first combined and then fed into the material cooler together through the second feed port, or fed in separately through separate cooling material feed ports. However, it is also possible to combine the material (medium particles) extracted from the fluidized bed material bed with the fine-grained material from the gas purification device before the material enters the cooler.

[0022] In another embodiment of the present invention, the material cooler includes a third feed inlet for cooling the material. The first feed inlet for cooling the material is arranged closer to the cooling gas inlet than the third feed inlet. The second material outlet is connected to the third feed inlet for cooling the material through a fifth connector for transporting the material with optimized color. In this way, the medium particle component and the coarse particle component can be supplied separately. Preferably, the third feed inlet is arranged between the first feed inlet and the second feed inlet.

[0023] In another embodiment of the present invention, the first material outlet and the second material outlet are respectively connected to the second feed inlet of the material cooler for transporting the material with optimized color. In addition, the solid outlet of the gas purification device is connected to the first cooled material feed inlet of the material cooler. Alternatively, the first material stream from the first material outlet and the second material stream from the second material outlet enter the material cooler at different positions. In this way, adaptive cooling can also be carried out, especially when the first material stream and the second material stream have different particle size distributions.

[0024] In another embodiment of the present invention, the device includes a depolymerization device. The depolymerization device is connected to the calciner for transporting the depolymerized material. Preferably, the depolymerization device is connected to the calciner through a preheater. For example and preferably, the depolymerization device is connected to the calciner through a flash dryer for transporting the depolymerized material. Preferably, at least one preheater is arranged between the flash dryer and the calciner. Further preferably, the depolymerization device is a hammer mill, a vertical roller mill, an impact mill, a pendulum roller mill or a stirred ball mill. Particularly preferably, the depolymerization device is a hammer mill.

[0025] In another embodiment of the present invention, the device includes a color recording device. The color recording device is configured to record the color of the product. The color recording device is arranged in the product stream downstream of the material cooler or along the product stream. By recording the color, both the necessary degree of reduction treatment can be carried out on the product to achieve color optimization, and the degree of reduction can be controlled within the necessary range, thereby saving the amount of reducing agent used.

[0026] In another embodiment of the present invention, the apparatus includes a reducing agent supply system. The reducing agent supply system is connected to the reduction device and is used to supply the reducing agent. Various gaseous, liquid or solid substances can be used as the reducing agent. Typical gaseous reducing agents include methane, hydrogen or carbon monoxide. Examples of liquid reducing agents include liquid hydrocarbons. An important example of a solid reducing agent is coal, especially pulverized coal, or biomass. If the reducing agent is a fuel, it is usually burned under oxygen-deficient conditions to create a reducing atmosphere, such as carbon monoxide in particular. The apparatus further includes a control device. The control device is used to adjust the amount of reducing agent provided by the reducing agent supply system. For this purpose, the control device is connected to the reducing agent supply system by transmitting control instructions or direct drive, such as a servo motor. The control device is also configured to adjust the supply amount of the reducing agent according to the color recorded by the color recording device. For this purpose, the control device particularly has a data connection with the color recording device to receive the product color recorded by the color recording device.

[0027] In addition, the control device also has, for example, a color threshold. If the color exceeds the threshold, that is, if the sample is too red, the supply amount of the reducing agent is increased to achieve stronger decolorization. If the color threshold is not reached, the supply amount of the reducing agent is reduced to avoid unnecessary consumption. For example, the color threshold can also be set in the form of an interval. Alternatively, the control device can be configured to assign a look-up table in which corresponding reducing agent dosages are set for different color value ranges. Thus, overall, sufficient decolorization can be achieved with the lowest amount of reducing agent, ensuring that the product meets the market acceptance standard.

[0028] The reducing agent and the fuel can be provided simultaneously. For example, biomass is used as the fuel, such as for near-stoichiometric combustion. Therefore, the residual oxygen content after combustion is usually low. Then, for example, hydrogen is added as the reducing agent. As a small molecule, hydrogen has excellent diffusion properties, but its cost as a fuel is higher than that of biomass.

[0029] In another embodiment of the present invention, an airtight material lock is arranged between the reduction device and the material cooler.

[0030] In another embodiment of the present invention, an airtight material lock is arranged between the calciner and the reduction device.

[0031] In another embodiment of the present invention, the device includes a gas supply system for supplying a reduction device. The gas supply system can adjust the gas flow rate and gas velocity. The device includes a control device. The device further includes a particle size specification device. The particle size specification device can be configured to determine the particle size distribution through a particle size measuring device and transmit it to the particle size specification device. Alternatively, the particle size specification device can be an input device in the traditional sense, through which an operator can directly input the particle size distribution or select it from a specified distribution. The particle size specification device can also be an interface with a central database system, and the database system includes, for example, data from laboratory analysis or data on the product to be delivered, so that the particle size distribution can be transmitted based on the delivered material. The particle size can also be recorded at least at two different locations, for example, in a flash dryer and upstream of a fluidized bed reactor. Through the particle size specification device, this two pieces of information and their location data are transmitted to the control device. The control device is configured to drive the gas supply system such that the control device adjusts the gas flow rate and gas velocity according to the particle size of the material particles specified by the particle size specification device. The particle size distribution affects the minimum fluidization velocity (initial fluidization point), that is, the critical point at which the gas flow just causes the solid particles to start fluidizing. Since the device preferably operates under the condition that the gas flow velocity is 5 to 15 times the minimum fluidization velocity, it is very necessary to record the particle size parameters, from which the corrected minimum fluidization velocity of the fluidized bed can be quickly determined.

[0032] In another embodiment of the present invention, the particle size specification device includes or is connected to a particle size measuring device. For example, the particle size measuring device can record the particle size and particle size distribution in or upstream of a calciner by means of light scattering. Alternatively, samples can also be taken upstream or downstream of the reduction device and sent to the particle size measuring device.

[0033] In another alternative embodiment of the present invention, the particle size specification device can be set as an input device for factory personnel to manually input relevant information. As another alternative, the particle size specification device can be configured as an interface through which information related to the particle size distribution can be received, such as information from an analysis laboratory system.

[0034] In another embodiment of the present invention, the reduction device includes deflection elements for guiding the flow of the material. For example, these deflection elements can be arranged at the lower part of the fluidized bed to extend the path of the largest particles, thereby extending the residence time of these largest particles in the reduction device.

[0035] In another embodiment of the invention, the reduction device comprises a deflection element for guiding the gas flow. This is particularly used to keep the gas flow that has left the fluidized bed and the fine particles carried away with the gas flow in the reduction device for a minimum residence time, thereby ensuring reliable reduction and color optimization. For example, this function can be achieved by a labyrinth-type flow guide structure.

[0036] In another embodiment of the present invention, a gas sensor is arranged downstream of the fluid of the gas outlet, and the gas sensor is configured to record the concentration of one or more substances selected from the following list of substances, including carbon monoxide, carbon dioxide, hydrogen, and methane. These substances can be used directly as reducing agents or can be generated in the reduction device. Therefore, the concentration recorded at the outlet can be used as an indicator of whether the reducing agent is excessive or not. It is preferred to detect the concentrations of carbon dioxide and carbon monoxide simultaneously, especially for determining the proportional relationship between the two.

[0037] In another embodiment of the present invention, the device is provided with a bypass channel connecting the calcining furnace and the material cooler to bypass the reduction device. The bypass channel is preferably used only during the startup and shutdown stages of the device. Through the bypass channel, the activated material in the reduction device can be directly transported to the material cooler.

[0038] In another embodiment of the invention, the reduction device comprises a dig tube for supplying the activated material. The dig tube preferably extends into the fluidized bed. In this way, the activated material is introduced directly into the fluidized bed, thereby extending the residence time, especially for the finest particles, thereby also ensuring color optimization of the finest particles.

[0039] Another aspect of the invention relates to a method for color optimization of activated materials using the apparatus of the invention. The method uses a material with a wide particle size distribution for color optimization in a reduction device, wherein the wide particle size distribution is characterized by at least 10 wt% of the particles being smaller than 50 μm and at least 10 wt% of the particles being larger than 250 μm. Such a wide particle size range (particle size distribution) is unconventional and difficult to handle in existing equipment. In conventional equipment, the fine particles are deactivated before the coarse particles are color optimized. The use of a fluidized bed reactor allows for the processing of such a wide particle size distribution material. As a result, a large amount of energy can be saved in the particle size reduction or deagglomeration process and / or the particle size classification step.

[0040] In another embodiment of the present invention, the particle size distribution is selected such that all particles are smaller than 2 mm.

[0041] In another embodiment of the invention, the particle size distribution is selected such that at least 5 wt % of the particles are larger than 900 microns.

[0042] In another embodiment of the present invention, the particle size distribution is selected such that at least 5 wt% of the particles are smaller than 20 microns.

[0043] In another embodiment of the present invention, at least 10 wt% of the material flow is discharged from the reduction device with the gas flow through the gas outlet and settles in the gas purification device. This means that the finest particles with extremely small particle sizes precisely account for at least 10 wt%. If a traditional method is used, this component is likely to lose its activity again in the reduction device. However, in the fluidized bed reactor of the present invention, this part of the particles is very quickly discharged by the fluidizing gas. Therefore, although color optimization has occurred, it has not lost its activity. Through this effect of the fluidized bed, the separation of the finest particle component is achieved synchronously.

[0044] In another embodiment of the present invention, the fluidization velocity in the reduction device is selected such that the fluidization velocity is 5 to 15 times the minimum fluidization velocity. The minimum fluidization velocity, or the initial fluidization point, is the flow velocity of the fluidizing gas at which the material begins to fluidize, that is, the theoretically lowest velocity at which a fluidized bed is formed. A higher fluidization velocity will significantly strengthen the difference in particle residence time with particle size. Specifically, it is precisely those finest particles that can quickly complete color optimization but will also quickly lose their activity that will be quickly discharged with the gas, that is, they only experience a relatively short residence time.

[0045] In another embodiment of the present invention, the temperature of the fluidizing gas in the reduction device is selected to be at least 700 °C. For example, in particular, exhaust gas with an oxygen content of less than 15 volume percent can be used as the gas. The lower the oxygen content and the higher the temperature of the exhaust gas, the less heating energy consumption is required, and thus the less fuel (and reducing agent) is required. However, preferably, the oxygen content of the exhaust gas exceeds 0.5 volume percent to maintain the combustion reaction and release heat energy. The color optimization process, such as the reduction of ferric iron, is an endothermic reaction and thus causes a temperature drop. In addition, the reduction device radiates heat. Especially in order to be able to compensate for these two effects and avoid cooling of the reduction equipment, the gas preferably has a corresponding residual oxygen content.

[0046] In another embodiment of the present invention, the reducing agent is directly introduced into the reduction device. For example, coal, especially pulverized coal, or biomass can be introduced into the reduction device by direct supply. In this way, on the one hand, a reducing atmosphere is directly generated in the fluidized bed, and on the other hand, heat is provided by combustion to maintain a constant temperature. Or, for example, hydrogen or methane can be directly introduced into the reduction device.

[0047] In another embodiment of the present invention, the reducing agent is introduced into the reduction device together with the gas flow. Especially gaseous reducing agents such as hydrogen and methane, as well as liquid reducing agents (such as liquid hydrocarbons), are suitable for this.

[0048] In another embodiment of the present invention, the reducing agent is introduced into the reduction device together with the material stream. This is particularly applicable to solid reducing agents such as coal, especially pulverized coal. In this case, the reducing agent will be mixed with the activated material before entering the reduction device, thus ensuring that all particles are in the same reducing atmosphere environment from the initial stage of the reaction.

[0049] In another embodiment of the present invention, for iron-containing minerals, especially clay, with an Fe2O3 content exceeding 20 wt%, the reduction degree of iron reaches at least 80%.

[0050] In another embodiment of the present invention, for iron-containing minerals, especially clay, with an Fe2O3 content between 10 wt% and 20 wt%, the reduction degree of iron is 50% to 80%. In this case, the proportion of the iron component to be reduced increases from 50% at 10 wt% to 80% at 20 wt%. This proportion change can be achieved in a linear or stepwise manner.

[0051] In another embodiment of the present invention, for iron-containing minerals, especially clay, with an Fe2O3 content below 10 wt%, the reduction degree of iron can reach 50%.

[0052] The device according to the present invention will be further described in detail below by means of an example, which is represented diagrammatically.

[0053] Figure 1 First Embodiment

[0054] Figure 2 Second Embodiment

[0055] Figure 3 Third Embodiment

[0056] Figure 1 The first embodiment of the present invention is shown for the production of color-optimized activated materials, especially clay. The material first enters a hammer mill 10, where it is depolymerized. This results in a relatively wide particle size distribution. The depolymerized material is then lifted and dried in a flash dryer 20. Then, the material enters a calciner 40 through a preheater 30, where it is thermally activated. However, when activation is carried out under oxidizing conditions, for example, oxidation of iron also occurs, generating Fe III , thus causing a red color change in the material. Oxidation does not necessarily occur quantitatively, that is, not all iron atoms are necessarily oxidized to Fe III。To reverse this process, the heat-activated material enters the fluidized bed reactor 50 through the first connector 1. For fluidizing the fluidized bed, the fluidized bed reactor 50 obtains fluidizing gas from the fluidizing gas supply system 100 through the combustion chamber 90, and the combustion chamber 90 is supplied through the reductant supply system 110, for example, supplying pulverized coal with an oxygen content in excess relative to the fluidizing gas in order to generate carbon monoxide in the combustion chamber. The fluidizing gas used can be, for example, oxygen-depleted waste gas from the preheater 30 or waste gas downstream of the gas purification device. The fluidized bed reactor 50 is operated, for example, in such a way that the fluidization velocity is 5 to 15 times the minimum fluidization velocity. Thus, the finest particles, i.e., those that are reduced most rapidly and have their color optimized, are rapidly discharged through the gas outlet 53, pass through the gas outlet 53 and the subsequent fourth connector 4 into the gas purification device 60, where these particles will be sedimented. The fluidized bed reactor 50 further includes two outlets for the color-optimized material. The first material outlet 51 is arranged at the lower part for removing the largest particles, while the second material outlet 52 is arranged at the upper part of the fluidized bed for removing the medium-sized particles. The color-optimized materials in all three particle size ranges are fed into the material cooler 70. For this purpose, the solid outlet 61 of the gas purification device 60 is connected to the first cooled material inlet 71 through the third connector 3. The first material outlet 51 is connected to the second cooled material inlet 72 through the second connector 2, while the second material outlet 52 is connected to the third cooled material inlet 73 through the fifth connector 5. Cooling gas is supplied to the material cooler 70 through the cooling gas inlet 75 and discharged through the cooling gas outlet 76. The cooled product can be removed through the cooled material outlet 74. The first cooled material inlet 71 is arranged closest to the cooling gas inlet 75, so that the finest particles can be cooled most rapidly, thus providing the best protection against re-oxidation. After cooling, the color is determined by the color recording device 80. In this way, the amount of reductant added through the reductant supply system 110 can be adjusted so as to add as little reductant as possible while still achieving a sufficient decolorization effect.

[0057] Figure 2 shows a second embodiment, which differs from the Figure 1 first embodiment shown in that the reductant is mixed with the activated material upstream of the fluidized bed reactor 50 and introduced into the fluidized bed reactor 50 together with the material. For example, pulverized coal can be supplied through the reductant supply system 110. In this way, the heat supply is generated directly in the fluidized bed of the fluidized bed reactor 50 by combustion. This embodiment is a preferred solution when the temperature of the fluidizing gas provided by the fluidizing gas supply system 100 is already close to (slightly lower than) the ignition temperature of the reductant.

[0058] Figure 3 shows a third embodiment, which differs from Figure 1The difference in the first embodiment shown is that the material components from the first material outlet 51 and the material components from the second material outlet 52 are first combined and then fed together into the second cooling material inlet 72. A gas sensor 120 is arranged downstream of the gas outlet 53. Thus, in addition to the color recording in the color recording device 80, the residual reducing components in the exhaust gas can also be used as a process control variable. The gas sensor 120 can be, for example, a carbon monoxide sensor. In addition, the finest material components are separated from the gas purification device 60. This component usually has the highest reactivity and can therefore be used for particularly high-grade products.

[0059] List of reference numerals

[0060] 1 First connector

[0061] 2 Second connector

[0062] 3 Third connector

[0063] 4 Fourth connector

[0064] 5 Fifth connector

[0065] 10 Hammer mill

[0066] 20 Flash dryer

[0067] 30 Preheater

[0068] 40 Calciner

[0069] 50 Fluidized bed reactor

[0070] 51 First material outlet

[0071] 52 Second material outlet

[0072] 53 Gas outlet

[0073] 60 Gas purification device

[0074] 61 Solid outlet

[0075] 70 Material cooler

[0076] 71 First cooling material inlet

[0077] 72 Second cooling material inlet

[0078] 73 Third cooling material inlet

[0079] 74 Cooling material outlet

[0080] 75 Cooling gas inlet

[0081] 76 Cooling gas outlet

[0082] 80 Color recording device

[0083] 90 Combustion chamber

[0084] 100 Fluidizing gas supply

[0085] 110 Reducing agent supply

[0086] 120 Gas sensor

Claims

1. An apparatus for thermal activation of mineral materials, wherein the apparatus comprises a calcination furnace (40), a reduction device, and a material cooler (70), wherein the calcination furnace (40) and the reduction device are connected by a first connector (1) for transferring the calcined material, and wherein the reduction device is connected to the material cooler (70) at least by a second connector (2) for transferring the material with optimized color, characterized in that, The reduction device is a fluidized bed reactor (50), wherein the reduction device includes a first material outlet (51) and a second material outlet (52), wherein the first material outlet (51) and the second material outlet (52) are each connected to a material cooler (70) for transporting the material with optimized color, wherein the reduction device includes a gas outlet (53), wherein the gas outlet (53) is connected to a gas purification device (60) through a fourth connector (4), wherein the gas purification device (60) includes a solid outlet (61), wherein the material cooler (70) includes at least one first cooled material inlet (71), a second cooled material inlet (72), a cooled material outlet (74), a cooling gas inlet (75) and a cooling gas outlet (76), wherein the first cooled material inlet (71) is arranged closer to the cooling gas inlet (75) than the second cooled material inlet (72), wherein the solid outlet (61) is connected to the first cooled material inlet (71) through a third connector (3) for transporting the material settled in the gas purification device (60), wherein the first material outlet (51) and / or the second material outlet (52) are connected to the second cooled material inlet (72) through a second connector (2) for transporting the material with optimized color.

2. The device according to claim 1, characterized in that, The material cooler (70) includes a third cooled material inlet (73), wherein the first cooled material inlet (71) is arranged closer to the cooling gas inlet (75) than the third cooled material inlet (73), wherein the second material outlet (52) is connected to the third cooled material inlet (73) through a fifth connector (5) for transporting the material with optimized color.

3. The device according to one of the preceding claims, characterized in that The first material outlet (51) and the second material outlet (52) are respectively connected to the second cooled material inlet (72) of the material cooler (70), and the solid outlet (61) of the gas purification device (60) is connected to the first cooled material inlet (71) of the material cooler (70).

4. The device according to one of the preceding claims, characterized in that, The device includes a color recording device (80), wherein the color recording device (80) is configured to record the color of the product, wherein the color recording device (80) is arranged in the product stream downstream of the material cooler (70) or along the product stream.

5. The device according to claim 4, characterized in that, The device includes a reducing agent supply system, wherein the reducing agent supply system is connected to the reduction device to supply a reducing agent, wherein the reduction device includes a control device, wherein the control device is configured to adjust the amount of the reducing agent supplied by the reducing agent supply system, and wherein the control device adjusts the amount of the reducing agent according to the color recorded by the color recording device (80).

6. The device according to one of the preceding claims, characterized in that, An airtight material lock is arranged between the reduction device and the material cooler (70).

7. The device according to one of the preceding claims, characterized in that, The device includes a gas supply system that can be adjusted in terms of flow rate and gas velocity, wherein the device includes a control device, and the control device is configured to drive the gas supply system, and the control device adjusts the flow rate and gas velocity of the gas supply according to the particle size of the material.

8. The device according to one of the preceding claims, characterized in that, A gas sensor (120) is arranged in a fluid passage downstream of the gas outlet (53), wherein the gas sensor (120) is configured to record the concentration of one or more substances selected from carbon monoxide, carbon dioxide, hydrogen, and methane.

9. A method for color optimization of activated materials using the device according to one of the preceding claims, characterized in that, In the reduction device, a material with a wide particle size distribution is selected for color optimization. The definition criteria for the wide particle size distribution are: at least 10 wt% of the particles are less than 50 microns, and at least 10 wt% of the particles are greater than 250 microns, or at least 5 wt% of the particles are greater than 900 microns.

10. The method according to claim 9, characterized in that, At least 10 wt% of the material flow is discharged from the reduction device through the gas outlet (53) by an air flow and settles in the gas purification device (60).

11. The method according to claims 9 to 10, characterized in that, The fluidization velocity in the reduction device is selected such that the fluidization velocity is 5 to 15 times the minimum fluidization velocity.

12. The method according to claims 9 to 11, characterized in that, The reducing agent is directly introduced into the reduction device.

13. The method according to any one of claims 9 to 12, wherein The reducing agent is introduced into the reduction device together with the air flow.

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