Color optimization of activated tones with ammonia
By employing ammonia as a reducing agent in the color optimization of activated clays, the method addresses carbon dioxide emissions, achieving efficient and environmentally friendly color optimization by converting iron-III centers into magnetite and enabling ammonia reuse.
Patent Information
- Application Number
- DE102023116181
- Authority / Receiving Office
- DE · DE
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-06-21
- Publication Date
- 2024-12-24
AI Technical Summary
Existing color optimization methods for activated clays produce carbon dioxide emissions due to the use of reducing agents like carbon or hydrocarbons, which is undesirable for environmental impact.
The use of ammonia as a reducing agent in the color optimization process, which is produced without carbon dioxide as a byproduct, allows for carbon dioxide-free color optimization by converting iron-III centers into magnetite, and unused ammonia can be reused as a fuel or for nitrogen oxide reduction.
Achieves carbon dioxide-free color optimization of activated clays by using ammonia, reducing environmental impact while maintaining efficiency and flexibility in ammonia utilization.
Smart Images
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Abstract
Description
[0001] The invention relates to a device and a method for color optimization of activated clays.
[0002] Activated clays are increasingly being used as additives, particularly in the cement industry. Unlike in the production of clinker from lime, no carbon dioxide is released from the raw material, the clay. However, most clays contain a certain amount of iron, which is usually oxidized to iron(III) during activation and gives the product an undesirable red color. Therefore, the hot activated clay is color-optimized immediately after activation. This has proven to be more efficient than, for example, activation under a reducing atmosphere. Color optimization usually takes place in a color optimization device downstream of the activation device. Coal or hydrocarbons such as propane are used for color optimization. However, this also produces carbon dioxide during the color optimization process.
[0003] The object of the invention is to provide a device and a method for color optimization of activated clays which avoids carbon dioxide emissions.
[0004] This object is achieved by the method having the features specified in claim 1, by the method having the features specified in claim 6, and by the use having the features specified in claim 10. Advantageous further developments emerge from the subclaims, the following description, and the drawing.
[0005] The device according to the invention serves to activate clays. The device is designed for activation and color optimization. Such devices are extensively known from the prior art. Preferably, the device comprises an activation device for thermal activation and a color optimization device downstream of the activation device. Alternatively, the activation and color optimization can also take place in a common housing, i.e., in a single component. The activation device can consist, for example, of a preheater and an entrained-flow calciner. The color optimization device can consist, for example, of a fluidized-bed reactor. The precise design of the activation device and the color optimization is arbitrary for the purposes of the invention and is known to those skilled in the art in a wide variety of embodiments.
[0006] According to the invention, the device, preferably the color optimization device, has an ammonia supply. It is essential that ammonia is supplied to the color optimization device as a reducing agent. This eliminates the need for coal or propane, for example. Ammonia is increasingly being produced in a green form, i.e., without carbon dioxide as a by-product. Thus, the use of ammonia enables carbon dioxide-free color optimization. It has been shown that ammonia is particularly suitable as a reducing agent for the color-providing iron(III) centers and is capable of converting them into gray-colored magnetite. A further advantage of using ammonia is that unused ammonia can be used in the process either as a carbon dioxide-free fuel and / or for the non-catalytic reduction of nitrogen oxides.This makes ammonia advantageous over, for example, renewably produced hydrogen, which at least has no positive impact on nitrogen oxides. Furthermore, ammonia is easier to store and handle.
[0007] In a further embodiment of the invention, the color optimization device has a gas outlet. The activation device has a gas inlet. The gas outlet and the gas inlet are connected to transfer unconverted ammonia. This allows the ammonia to be used either as fuel or, preferably, after the actual combustion, for example, and in particular, as a substitute fuel, for the non-catalytic reduction of nitrogen oxides produced during combustion.
[0008] In a further embodiment of the invention, the color optimization device is a fluidized-bed reactor. The fluidized-bed reactor has proven particularly suitable for color optimization with ammonia.
[0009] In a further aspect, the invention relates to a method for color optimization of an activated clay in a device according to the invention. For color optimization, ammonia is added to the activated clay. Instead of adding coal, propane, or a comparable reducing agent, which produces carbon dioxide as a byproduct, this process is not necessary. This also allows for climate-neutral color optimization.
[0010] In a further embodiment of the invention, color optimization is performed at temperatures between 450 °C and 900 °C. Successful color optimization can thus be achieved within the temperature range of 450 to 550 °C, which is energetically advantageous compared to the conventional higher temperature range of 800 to 900 °C. Furthermore, this reduces the problems and risks of reoxidation during cooling.
[0011] In a further embodiment of the invention, the ammonia not converted during color optimization is fed from the activation device. This allows the ammonia to be used as fuel and / or as an agent for the SNCR, with the SNCR conversion preferably being carried out in a temperature range of 800°C to 900°C, for example, in the middle or at the end of an entrained-flow calciner as part of the activation device.
[0012] In a further embodiment of the invention, the ammonia is supplied in a gas mixture, preferably a carbon dioxide-containing gas mixture. For example, an exhaust gas is used as the carbon dioxide-containing gas mixture.
[0013] In a further aspect, the invention relates to the use of ammonia for color optimization of an activated clay. Previously, carbon or hydrocarbon compounds or hydrogen were used for color optimization. The use of ammonia, especially green-produced ammonia, is not only particularly suitable for color optimization, but is also particularly well-suited for carbon dioxide-free color optimization.
[0014] The device according to the invention is explained in more detail below using an embodiment shown in the drawing. Fig. 1 exemplary device
[0015] In Fig.1 shows an exemplary device in a highly schematic manner, which also serves to illustrate the method.
[0016] The clay to be activated is introduced into a preheater 10 via material feed 11, preheated, and from there transferred to a calciner 20, where the thermal activation of the clay takes place. A gas stream, which can originate from the material cooler 4ß, and fuel are fed to the calciner 20 via a gas feed, and fuel is fed via the fuel feed 22. A secondary fuel, such as biomass, can be used as the fuel. The activated clay 23 is transferred to the color optimization device 30, for example, a fluidized-bed reactor. Ammonia is fed to the color optimization device 30 via an ammonia feed 31. The ammonia reacts with the iron(III) compounds and leads to a decolorization / graying of the product.Unused ammonia is fed via the ammonia transfer 32 into the calciner 20, for example, into a combustion chamber of the calciner 20, where, for example, substitute fuels are burned at a temperature of 850 °C for at least 2 seconds to non-catalytically convert the nitrogen oxides produced there. The activated and color-optimized clay is transferred from the color optimization device 30 to a material cooler 40 and removed from it as the finished product 41. Reference symbol 10 preheaters 11 Material supply 12 Exhaust outlet 20 Calciners 21 Gas supply 22 Fuel supply 23 activated sound 30 Color optimization device 31 Ammonia supply 32 Ammonia transfer 40 material coolers 41 product
Claims
[1] Device for activating tones, wherein the device is designed for activation and color optimization, characterized by that the device has an ammonia supply (31). [2] Device according to claim 1, characterized by that the device has an activation device for thermal activation and a color optimization device (30) connected downstream of the activation device. [3] Device according to claim 2, characterized by that the color optimization device (30) has an ammonia supply (31). [4] Device according to one of the preceding claims, characterized by in that the color optimization device (30) has a gas outlet, wherein the activation device has a gas inlet, wherein the gas outlet and the gas inlet are connected to one another for the transfer of unreacted ammonia. [5] Device according to one of the preceding claims, characterized bythat the color optimization device (30) is a fluidized bed reactor. [6] Method for color optimization of an activated tone (23) in a device according to one of the preceding claims, characterized by that ammonia is added to the activated clay (23) to optimize the color. [7] Method according to claim 6, characterized by that the colour optimization is carried out at 450 °C to 900 °C, preferably at 450 to 550 °C. [8] Method according to one of claims 6 to 7, characterized by that the ammonia not converted during color optimization is fed from the activation device. [9] Method according to one of claims 6 to 8, characterized by that the ammonia is supplied in a gas mixture, preferably in a gas mixture containing carbon dioxide. [10] Use of ammonia to optimize the color of an activated clay (23).