METHOD FOR MAKING BRICKS

Description

[0001] The invention relates to a method for producing bricks according to claim 1.

[0002] It is known that large amounts of carbon dioxide are released into the environment during commercial brick production. On the one hand, carbon dioxide is released during the transport of raw materials from the quarries to the brickyards by truck. On the other hand, carbon dioxide is emitted during the production of the bricks themselves in the brickyards, particularly during the firing step due to the decomposition of carbonates in the green bricks.

[0003] WO 02 / 081409 A1 discloses a process for producing bricks, in which a large amount of lime is added to the blanks before firing.

[0004] From BE 510 028 A a process for the production of bricks is known, whereby the bricks are moistened and then gassed with carbon dioxide or carbonic acid at normal pressure or overpressure for a long period of time.

[0005] A method for producing a non-slip tile is known from CN 108 842 991 A.

[0006] In view of climate change and in times of increasing environmental awareness, it is therefore important to reduce carbon dioxide emissions during brick production.

[0007] The object of the invention is therefore to provide a method of the type mentioned at the outset with which the disadvantages mentioned can be avoided and with which carbon dioxide emissions during brick production can be reduced.

[0008] According to the invention, this is achieved by the features of patent claim 1.

[0009] This has the advantage that carbon dioxide emissions during brick production can be reduced and a better carbon dioxide balance can be achieved than with conventional brick production. By fumigating the fired brick with carbon dioxide under a predefined pressure and for a predefined fumigation time in a carbonate production step following the firing step, carbon dioxide is enriched in the brick in the form of carbonates and the carbonate content of the brick is correspondingly increased and carbon dioxide is consumed in this chemical reaction. This allows carbon dioxide to be efficiently bound in the mass-produced brick and contributes to combating climate change. The carbon dioxide used to fumigate the bricks can come from the brick production processes themselves or from other processes in which carbon dioxide is released.The greenhouse gas carbon dioxide, which is produced as a waste product in various processes, can thus be usefully bound in the bricks in the form of carbonates.

[0010] The subclaims relate to further advantageous embodiments of the invention. Express reference is hereby made to the wording of the patent claims, whereby the patent claims are incorporated into the description at this point by reference and are deemed to be reproduced verbatim.

[0011] A method for producing bricks is claimed, wherein a brick blank is fired in a firing step and, in a carbonate production step following the firing step, the fired brick is fumigated with carbon dioxide under a predeterminable pressure and for a predeterminable gassing time, with firing temperatures not exceeding 800°C. This results in the advantage that carbon dioxide emissions during brick production can be reduced and a better carbon dioxide balance can be achieved than in commercial brick production. By fumigating the fired brick with carbon dioxide under a predeterminable pressure and for a predeterminable gassing time in a carbonate production step following the firing step, carbon dioxide is enriched in the brick in the form of carbonates and, accordingly, the carbonate content of the brick is increased and carbon dioxide is consumed in this chemical reaction.This allows carbon dioxide to be efficiently bound in the mass-produced bricks, thus contributing to combating climate change. The carbon dioxide used to fumigate the bricks can come from the brickmaking process itself or from other processes that release carbon dioxide. The greenhouse gas carbon dioxide, produced as a waste product in various processes, can thus be effectively bound in the bricks in the form of carbonates.

[0012] [continued on page 3 of the original description]

[0013] The brick is preferably a building ceramic, in particular a masonry tile or a roof tile.

[0014] In the firing step, at least one previously formed brick blank is fired.

[0015] It may preferably be provided that firing temperatures of at least 600°C, in particular at least 650°C, preferably at least 700°C, are used in the firing step. The decomposition of the carbonates in the brick greens begins at approximately 600°C at atmospheric pressure and is greatly enhanced by increasing temperatures.

[0016] According to the invention, the firing temperatures are a maximum of 800°C. It has been shown that at low temperatures of less than or equal to 900°C, silicate formation occurs only to a small extent, allowing a higher amount of carbon dioxide to be bound in the brick as carbonate.

[0017] The brick blank may have been pressed in a forming step under one or more predetermined pressures before the firing step.

[0018] In the carbonate production step, the fired brick is gassed with carbon dioxide, which enriches and stores the carbon dioxide in the form of carbonates within the fired brick. The carbon dioxide is bound in or on the brick through a chemical reaction, primarily as calcium carbonate, but also as CaMg carbonate and / or Mg carbonate. The brick acts as a carbonate reservoir.

[0019] It can particularly preferably be provided that several brick greens are arranged on a transport device in a stacking step preceding the firing step, then moved into a kiln, and fired in the kiln during the firing step. In this case, the brick greens are already formed before the stacking step.

[0020] Preferably, it can be provided that the transport device is a carriage which in particular has several levels for the bricks.

[0021] The brick greens are stacked on the trolley. Stacked means that the brick greens are arranged at a particular distance from each other on the various levels of the trolley, so that as much of the bricks' surface area or reaction surface as possible comes into contact with the gaseous carbon dioxide.

[0022] The carriage is moved into the firing chamber, particularly in an automated process. For this purpose, several carriages can be moved into the kiln automatically at continuous, time-separated intervals.

[0023] Alternatively, it can be provided that several trolleys are moved discontinuously into the kiln.

[0024] It may also be preferred that several carriages be located in the kiln simultaneously during the firing step. This may be particularly the case when a tunnel kiln is used as the preferred kiln.

[0025] It can preferably be provided that, after the firing step, the fired bricks on the transport device are fumigated with carbon dioxide in the carbonate production step. In this case, the fired bricks on the transport device, in particular on the trolley, can be fumigated with carbon dioxide after the firing step, and the bricks do not have to be removed from the transport device and sized in the kiln, thus saving time.

[0026] It can preferably be provided that the carbonate production step takes place in a pressure chamber. The gassing with carbon dioxide can be carried out automatically and program-controlled, provided the transport device is located in the pressure chamber. Whether the transport device, in particular the trolley, is located in the pressure chamber can be easily checked using sensors. Such sensors can include, for example, optical sensors or pressure sensors.

[0027] It can preferably be provided that several carts are moved into the pressure chamber one after the other via a lock system. This allows the specified carbon dioxide partial pressure in the pressure chamber to be maintained essentially continuously and does not need to be readjusted for each cart, thus saving time and making the process simple and efficient.

[0028] Alternatively, it can be provided that transport devices, in particular trolleys, are continuously moved into the pressure chamber. This can be particularly the case when gassing with carbon dioxide under atmospheric pressure. The carbonate production step can be carried out in a simple chamber.

[0029] It may particularly preferably be provided that the carbon dioxide partial pressure is at least 0.1 MPa, in particular at least 0.5 MPa, preferably at least 1 MPa. Under such elevated pressures, bricks can be efficiently enriched with carbonates.

[0030] It may further be preferable for the fumigation duration to be at least 5 minutes, in particular at least 10 minutes, preferably at least 15 minutes. Even at these short periods, a carbonate enrichment in the bricks could be observed, which is economically feasible.

[0031] It may preferably be provided that the fired bricks have a residual heat of at least 25°C, in particular at least 50°C, preferably at least 75°C, at the beginning of the carbonate production step. It has been shown that the enrichment of carbonates in bricks in the carbonate production step works particularly well when the bricks are heated or when the bricks have a temperature greater than room temperature, in particular greater than 20°C.

[0032] For this purpose, it can preferably be provided that the transport device with the bricks arranged thereon is automatically moved into the pressure chamber after the firing step. Based on the speed of the transport device and the distance it travels from the kiln to the pressure chamber, the temperature drop of the bricks per unit of time can be determined empirically, for example, and the temperature of the bricks can be precisely adjusted essentially immediately before entering the pressure chamber by adjusting the speed of the transport device. For this purpose, test series can be conducted on the system at different firing temperatures.

[0033] Sensors can also be used to precisely measure the temperature of the bricks after the firing step, either outside the kiln or, preferably, in the pressure chamber itself. Infrared thermometers, for example, could be used for non-contact measurements to determine the temperature of the bricks after the firing step.

[0034] Alternatively, contact thermometers could be used to determine the temperature of the bricks.

[0035] It can also preferably be provided that the carbonate production step takes place at a temperature of at least 50°C. If the residual heat of the bricks is below 50°C or this minimum temperature is to be maintained constant over a longer period of time, it can preferably be provided that the bricks are heated to at least 50°C in the carbonate production step.

[0036] Surprisingly, it has been shown that carbonate enrichment in the bricks occurs particularly efficiently due to a synergistic effect of the aforementioned minimum temperatures and pressures. Particularly efficient carbonate enrichment in the bricks was observed at temperatures of at least 50°C. Increased pressures also contributed to the particularly rapid and efficient enrichment of carbonates in the bricks.

[0037] If residual heat from the firing step is present in the bricks, energy can also be saved in the carbonate production step, since the bricks either do not need to be heated at all or only slightly to reach the above-mentioned minimum temperatures.

[0038] Particularly preferably, the fired bricks may be moistened before the carbonate production step. It has been shown that moistening the bricks, especially with water, greatly promotes carbonate enrichment on or within the bricks.

[0039] For this purpose, it may be provided that the fired bricks are moistened essentially immediately before the carbonate production step, i.e. before fumigation with carbon dioxide.

[0040] Furthermore, a brick is provided which was produced according to the method described above and which has a carbonate content with a mass fraction of at least 1%, preferably at least 5%, in particular at least 10%.

[0041] The following are principles for understanding and interpreting the disclosure in question.

[0042] Characteristics are usually introduced with an indefinite article, "ein, eine, eines, einer." Therefore, unless the context indicates otherwise, "ein, eine, eines, einer" is not to be understood as a number.

[0043] The conjunction "or" is to be interpreted as inclusive and not exclusive. Unless the context indicates otherwise, "A or B" also includes "A and B," where "A" and "B" represent any characteristics.

[0044] By means of an ordering number, for example, "first," "second," or "third," a feature X or an object Y is distinguished in particular in multiple embodiments, unless otherwise defined by the disclosure of the invention. In particular, a feature X or object Y with an ordering number in a claim does not mean that an embodiment of the invention covered by this claim must have a further feature X or another object Y.

Claims

1. Method for manufacturing bricks, wherein brick blanks are fired in a firing step and, in a carbonate production step following the firing step, the fired brick is exposed to carbon dioxide under a pre-settable pressure for a pre-settable gassing period, characterized in that the firing temperatures are a maximum of 800°C.

2. Method according to claim 1, characterized in that a plurality of brick blanks are arranged on a transport device in a stacking step preceding the firing step, then moved into a kiln and fired in the firing step in the kiln.

3. Method according to claim 2, characterized in that after the firing step, the fired bricks on the transport device are exposed to carbon dioxide in the carbonate production step.

4. Method according to one of claims 1 to 3, characterized in that the carbonate production step takes place in a pressure chamber.

5. Method according to one of the claims 1 to 4, characterized in that the partial pressure of carbon dioxide is at least 0.1 MPa, in particular at least 0.5 MPa, preferably at least 1 MPa.

6. Method according to one of the claims 1 to 5, characterized in that the gassing time is at least 5 minutes, in particular at least 10 minutes, preferably at least 15 minutes.

7. Method according to one of the claims 1 to 6, characterized in that the fired bricks have a residual heat of at least 25°C, in particular at least 50°C, preferably at least 75°C, at the beginning of the carbonate production step.

8. Method according to one of claims 1 to 6, characterized in that the carbonate production step takes place at a temperature of at least 50°C.

9. Method according to one of claims 1 to 8, characterized in that the fired bricks are moistened before the carbonate production step.