Method and system for treating concrete particles

Abstract

The invention comprises a method and a system (1) for treating concrete particles (2) for subsequent recycling of said concrete particles. In the method, a container (4) of the system (1) is filled with concrete particles (2), the container being airtight at least in certain areas. Subsequently, a gas containing CO2 is input continuously or discontinuously depending on the degree of absorption of CO2 by the concrete particles (2) in the container (4), said degree being determined by at least one sensor (8, 9, 10). After a predetermined CO2 saturation of the concrete particles (2) has been detected, the concrete particles (2) that have become rich in CO2 are removed.

Description

Technical Field

[0001] The present invention relates to a method and a system for processing concrete particles and subsequently recycling the concrete particles. In particular, the present invention relates to a method and a system for enriching concrete particles with CO2. In addition, the present invention also relates to concrete particles that can be produced according to the method of the present invention, and a concrete. Background Art

[0002] In addition to gravel and sand, cement is crucial for the production of concrete. However, the production of cement not only releases a large amount of greenhouse gas emissions but is also an important cost factor in concrete production. Nowadays, recycling concrete has played an important role in protecting the resources of gravel and sand. However, conventional recycling processes can neither recycle cement nor reverse or avoid greenhouse gas emissions. Conventional recycling is usually carried out by demolishing abandoned houses or other concrete structures. Then the demolished concrete is crushed into concrete particles, which can be used as a substitute for gravel, for example, when producing new concrete. After adding new cement, recycled concrete is produced. However, compared with virgin concrete, this conventional recycled concrete usually has reduced mechanical properties. Virgin concrete is understood to be non-recycled concrete. Therefore, to obtain recycled concrete with a quality similar to that of virgin concrete, the cement content in conventional recycled concrete is usually increased by 10%. In addition, the concrete particles obtained from the demolished concrete can be used loosely in an unbonded state, for example, as road construction materials. However, this application is severely restricted because toxic metals are contained in the concrete during the production process, and these toxic metals can be dissolved by rainwater, especially in the loose (unbonded) state of the concrete particles known in the prior art, thus polluting the groundwater. For the above reasons, today's concrete recycling can at best produce low-grade gravel substitutes; however, this recycling can neither reduce the greenhouse gas emissions of concrete nor use the concrete particles loosely without hesitation. Summary of the Invention

[0003] An object of the present invention is to provide an improved method and system for processing concrete particles for subsequent recycling of the concrete particles. Preferably, at least partially, the above problems of known recycling methods are eliminated.

[0004] In order to prepare concrete particles for subsequent recycling of said concrete particles, treatment can be carried out with carbon dioxide (hereinafter referred to as CO2). Compared with a reference concrete for recycling of enriched concrete having substantially the same composition (including cement, gravel, sand and non-enriched concrete particles), enriched concrete (including cement, gravel, sand and CO2-rich concrete particles) can have a higher compressive strength with substantially the same slump. Slump is a parameter of the consistency of freshly mixed concrete. Similarly, with a corresponding reduction in the cement content in the enriched concrete, the same compressive strength can be obtained compared to the reference concrete with unchanged composition.

[0005] These relationships can be understood from the following table. These show the composition (Table 1) and measurement results (Table 2) of the reference concrete and various test concretes. The reference concrete contains conventional concrete particles that are not rich in CO2. On the other hand, the concrete particles of the test concretes are rich in CO2. The compressive strength is determined according to the standard SN EN 206:2013+A1:2016 and the SIA bulletin "Recycled Concrete 2030". The slump is determined according to the standard SN EN 12350-5:2019.

[0006]

[0007] Table 1

[0008]

[0009] Table 2

[0010] Enriched concrete with a correspondingly reduced cement content (such as Test Concrete 3) significantly reduces greenhouse gas emissions. For example, with a 10% reduction in cement, the emissions from concrete production can be reduced by approximately 8.5%. On the other hand, in this method, the existing CO2 emissions can be combined with the concrete particles and thus reduced. For example, on average, 10 kg of CO2 is bound per 1000 kg of concrete particles, and the emissions can be reduced by an average of 4% again. Under ideal conditions, this technology can reduce the CO2 emissions generated in the production of recycled concrete by approximately 12.5%.

[0011] In addition, it has been shown that enriched concrete has higher carbonation resistance. Carbonation resistance is a decisive factor in the corrosion of reinforced castings in concrete and the occurrence of damage in concrete construction. Similarly, the enrichment of CO2 in the concrete particles can lead to better binding of the above-mentioned toxic metals and significantly reduce their unintentional leakage into the environment. This expands the application possibilities of loose concrete particles.

[0012] A method according to the invention claimed, in particular for treating concrete particles, especially for enriching concrete particles with CO2 for subsequent recovery, comprises the following method steps: filling at least a partially airtight container with concrete particles. Supplying a volume flow rate of a gas containing CO2, depending on the amount of CO2 absorbed by the concrete particles in the container as determined by at least one sensor. The supply of the gas can be continuous or discontinuous. Determining whether the concrete particles have reached a predetermined CO2 saturation, and otherwise continuing the foregoing method step regarding the supply of the gas. According to the present application, if the predetermined CO2 saturation of the concrete particles has not been reached, the gas can be supplied continuously or discontinuously until that saturation is reached. In addition, the method comprises removing the CO2-enriched concrete particles from the container. Once the concrete particles are removed, they can be used in further method steps to produce recycled (enriched) concrete containing CO2-enriched concrete particles. To this end, the CO2-enriched concrete particles can be treated with cement, water, sand and gravel to produce concrete.

[0013] The absorption of CO2 by the concrete particles can be understood to mean that CO2 diffuses into the concrete particles and a chemical reaction occurs. For this absorption method, no additional water, especially water in liquid form, needs to be added to the container. The concrete particles include pores into which CO2 can diffuse. There may be water in the pores, i.e., so-called pore water, and the CO2 reacts chemically with the pore water. The pore water is in phase equilibrium with the cement phase in the concrete particles and contains calcium ions. When CO2 is (chemically) absorbed, carbonates and bicarbonate ions are formed. As a result, the resulting pore solution is supersaturated with respect to calcium carbonate (CaCO3), specifically its polymorphic minerals calcite, aragonite and vaterite, and the pores are filled.

[0014] However, depending on their composition, the concrete particles may only absorb a certain amount of CO2. This maximum CO2 saturation may be between 30 and 45 kilograms of CO2 per 1000 kilograms of concrete particles, depending on their composition. The present method can achieve (at least approximately) the respective maximum CO2 saturation of the concrete particles in the container. For example, when no change in the CO2 concentration and / or the pressure can be detected for each initial gas volume, the maximum CO2 saturation of the concrete particles is reached. However, the method can also be stopped prematurely when a predetermined CO2 saturation lower than the maximum CO2 saturation is reached. The predetermined CO2 saturation of the concrete particles can be between 5% and 100% of the maximum CO2 saturation. However, high saturation values may only be achieved after sufficient long-term CO2 inflation and accordingly require a larger amount of CO2. However, good material properties can already be achieved at a given CO2 saturation between 5 kilograms of CO2 absorbed per 1000 kilograms and 15 kilograms of CO2 absorbed per 1000 kilograms. This corresponds to a given CO2 saturation of approximately 10% to 50% of the maximum CO2 saturation.

[0015] The amount of CO2 absorbed by the concrete particles generally decreases exponentially over time until the maximum CO2 saturation is reached. For example, if the change in the measured CO2 absorption over a certain time interval is less than a predetermined limit value, the predetermined CO2 saturation can be considered to have been reached. Alternatively or in addition, to determine the predetermined CO2 saturation, for example, a curve of the CO2 absorption that has occurred over time, determined by at least one sensor, can be plotted and extrapolated. The extrapolation can be used to determine the (theoretical) limit value of the CO2 absorption that has occurred, which corresponds to the maximum CO2 saturation of the concrete particles in the container. When a predetermined percentage of this limit value (or respectively a predetermined CO2 saturation) is reached, the gas supply can be stopped.

[0016] Gas is supplied to the container, and the volume flow rate supplied to the container is adjusted separately, which can be achieved by adjusting the intake valve. The intake valve can be arranged in the supply pipeline of the container. According to the amount of CO2 absorbed, the control unit performs the adjustment of the intake valve, that is, adjusts the volume flow rate separately. The control unit is operably connected to the at least one sensor and the intake valve. Advantageously, the volume flow rate of the supplied gas (after the initial filling of the container) compensates for the CO2 that has been absorbed. In this way, the CO2 concentration in the container is kept as constant as possible. The advantage of this is that with a higher CO2 concentration and a uniform distribution of CO2 in the container, on the one hand, the method runs faster, and on the other hand, uniform enrichment of CO2 in the concrete particles can be achieved. The control unit can determine the theoretical amount of CO2 present in the container without CO2 absorption based on the known gas composition, or the CO2 content of the gas, and the known volume flow rate supplied through the intake valve. Similarly, the theoretical pressure in the container can be determined. For this purpose, the intake valve can include a flow sensor for determining the volume flow rate flowing through the intake valve, or the flow sensor can be connected upstream or downstream of the intake valve. Alternatively or in addition to using a flow sensor, according to the intake valve setting, the achieved volume flow rate can be stored as data records in the control unit.

[0017] The gas supply can be interrupted at least temporarily (discontinuous supply of gas). This can be done by repeatedly performing the following step sequence: opening the intake valve operably connected fluidly to the container, introducing gas containing CO2 into the container, and closing the intake valve. When the intake valve is closed, the amount of CO2 absorbed can be easily determined. Advantageously, when the intake valve is open, the volume flow rate of the supplied gas compensates for the CO2 absorbed during that time (during the period when the intake valve is closed). This discontinuous inflation can be continued until the concrete particles reach a predetermined CO2 saturation. The discontinuous gas supply is particularly suitable for containers that are at least partially open to the environment or ambient air (during inflation). Such containers can especially be open at the top.

[0018] As an alternative to discontinuous inflation, the volume flow rate can be continuously adjusted during inflation according to the amount of CO2 absorbed (continuous supply of gas). Advantageously, the volume flow rate of the supplied gas compensates for the CO2 that has been absorbed. If the absorption of CO2 decreases exponentially over time, the supplied volume flow rate can be adjusted to decrease exponentially.

[0019] The container can be (initially) filled with gas until the desired gas filling level of the container is reached. Alternatively as a supplement, the container can be (initially) filled until a predetermined CO2 concentration, in particular a CO2 concentration of more than 95% is present in the container. After the initial filling, the volume flow can be reduced (further continuous supply) or interrupted during this period (discontinuous supply). Here, as already described, the volume flow of the further supply can be controlled in such a way as to compensate for the CO2 absorbed in the container.

[0020] To determine the amount of CO2 absorbed by the concrete particles, at least one sensor can be arranged in the container or fluid-operably connected to the container. For example, the at least one sensor can be a CO2 concentration sensor for measuring the CO2 concentration in the container. The theoretical amount of CO2 in the container (without absorption) can be determined by the amount of CO2 supplied (and possibly the measured amount of CO2 removed). Thus, the amount of absorption can be determined by the difference between the theoretical amount of CO2 and the actual (measured) amount of CO2 measured by the concentration sensor in the container. As described above, for example, when the difference between the theoretical amount of CO2 and the actual amount of CO2 in the container is less than a predetermined limit within a certain time interval, a predetermined CO2 saturation may have been reached. Alternatively, when the limit value of the above difference is reached during the entire process duration so far, a predetermined CO2 saturation may have been reached, or the gas filling can be stopped. Alternatively, when the theoretical limit value of the CO2 absorption amount determined by extrapolation has been reached, a predetermined CO2 saturation may have been reached. Determining the amount of CO2 absorbed by measuring the CO2 concentration is particularly suitable for containers that cannot be hermetically sealed.

[0021] As an alternative or supplement to the CO2 concentration sensor, the amount of CO2 absorbed by the concrete particles can also be determined by measuring the pressure. When CO2 comes into contact with the concrete particles and CO2 is absorbed, the pressure of a given volume of gas containing CO2 decreases. That is, the difference between the theoretical pressure that should exist in the container without absorption and the pressure actually measured in the container can be used as the amount of CO2 absorption that has occurred. The theoretical pressure can be approximated at least by the known volume of the container and the volume flow of the supply (and optionally the discharge). Determining the amount of CO2 absorption by measuring the pressure is particularly suitable for airtight containers, especially in the case of discontinuous gas supply to the container. As described above, for example, when the pressure change within a certain time interval is less than a predetermined limit value or the amount of CO2 absorption that has occurred has reached a certain theoretical limit value, a predetermined CO2 saturation can be reached.

[0022] In addition, when determining the amount of CO2 absorbed, the measured temperature can also be taken into account. Since heat is released during the chemical reaction process, this temperature change will also affect the pressure. By means of supplementary temperature measurement, the influence of the temperature change on the theoretical pressure can be taken into account. When determining the amount of CO2 absorbed by measuring the CO2 concentration, the supplementary temperature measurement can also be taken into account.

[0023] Alternatively or additionally, when determining the amount of CO2 absorbed, the measured weight can also be taken into account. For this purpose, at least one sensor can be a scale or a load cell that is operably connected to the container and the control unit. For example, the weight of the concrete particles measured before inflation can be used to at least approximately determine the volume available for inflation in the container. For example, this can be used to determine the theoretical pressure. In addition, the weight difference between the concrete particles before inflation and the CO2-rich concrete particles after inflation can be determined. This provides information about the actual amount of CO2 absorbed. This information can be used by companies, for example, to trade CO2 certificates, also known as emission certificates.

[0024] According to this design, the relative humidity in the container can also be measured because gaseous water is released during CO2 absorption. Although the relative humidity of the supplied gas may be less than 1%, when the maximum CO2 saturation is reached, the relative humidity in the container may be 50% to 95%. Therefore, when determining the amount of CO2 absorbed, the measured relative humidity can also be additionally taken into account.

[0025] As described above, by measuring the pressure and / or the CO2 concentration, by measuring the weight and / or the temperature and / or the relative humidity, the amount of CO2 absorbed that has occurred can be determined more precisely. For example, the measured values and / or known values can be correlated with each other through physical connections, such as the ideal gas equation and the law of conservation of mass. This enables more precise and comprehensive monitoring of the CO2 absorption that has occurred.

[0026] Depending on the composition, the gas input into the container may include gaseous water and / or nitrogen and / or oxygen in addition to CO2. The gas to be input into the container may be stored in a storage tank in liquid and / or gas form before being input into the container. Advantageously, the gas contains 95% to 100% CO2. According to the present application, the gas may contain renewable CO2. Renewable CO2 is understood to mean biogenic CO2 or CO2 extracted from the atmosphere. The advantage of biogenic CO2 is that it can usually be obtained in pure form and does not require treatment. For example, biogenic CO2 can be obtained as a by-product of biogas production or from the combustion of biomass (biological materials including carbon, hydrogen, and oxygen). Alternatively, the gas can also be waste gas containing 10% to 25% CO2. For example, the waste gas from a cement factory can be used for cement production.

[0027] Primary concrete typically contains sand, gravel, and cement. Concrete particles obtained, for example, as demolished concrete can also include mortar, depending on the type previously used. The concrete particles typically contain 4 to 10% by weight of calcium oxide. In particular, the concrete particles include hydrated cement. Hydrated cement is understood as the reaction of cement with water, and the water adheres to the cement. This reaction is called hydration, and the reaction product is called hydrated cement. During the hydration process, the cement can chemically bind up to 25% of its mass of water and physically bind up to 15% of its mass of water. Demolished concrete can be crushed. Good results can be obtained when the particle diameter is from 0.05 mm to 50 mm. For processing, the individual components of the concrete particles generally cannot be separated from each other.

[0028] After reaching a predetermined CO2 saturation, the excess gas present in the container can be discharged. The excess gas can be processed for reuse and returned to the storage tank of the system. Alternatively, the excess gas can also be placed in a collection container filled with concrete particles, and the method can be re-executed in the collection container. For example, the method can be alternately implemented in the container and the collection container. Alternatively, a collection container filled with more concrete particles can be used as a passive filter, i.e., without actively controlling the CO2 saturation. The concrete particles arranged in the collection container can at least partially absorb the excess gas, and in particular, can also completely absorb the excess gas.

[0029] Before supplying the gas containing CO2, in addition to the concrete particles, air may also be present in the container. When the inlet valve is opened for inflation, a gas mixture including CO2 and air is formed in the container. To increase the CO2 concentration in the container, especially during the initial filling of the container, in addition to supplying the gas containing CO2, the gas mixture can be continuously or discontinuously discharged from the container. This method advantageously increases the percentage of CO2 in the container. The gas mixture discharged from the container can be processed as described for the excess gas, or can also be input into the collection container. After reaching a predetermined CO2 concentration in the container, the discharge of the gas mixture and optionally the gas supply can be stopped at least temporarily.

[0030] The discharge of gas from the container can be controlled by the outlet valve. Like the inlet valve, the outlet valve can include a flow sensor for determining the volume flow rate flowing through the outlet valve, or the flow sensor can be connected upstream or downstream of the outlet valve. The upstream or downstream flow sensor is also operably connected to the control unit. As an alternative or supplement to using the flow sensor, according to the setting of the outlet valve, the volume flow rate flowing through can be stored as data records in the control unit. In addition, a CO2 concentration sensor can also be connected upstream or downstream of the outlet valve.

[0031] The supply and / or discharge of gas can be controlled by at least one pump operably connected to a control unit. For example, the supply of gas to a container and / or the discharge of a gas mixture from the container and / or the discharge of excess gas from the container can be induced by a negative pressure (relative to the ambient pressure). The negative pressure can be between 80,000 and 96,000 Pascals. However, the method can also be carried out at ambient pressure or a higher pressure.

[0032] The invention also relates to a system for treating concrete particles, in particular for enriching the concrete particles with CO2 for subsequent recovery of the concrete particles. The system includes a storage tank and at least partially airtight container. The gas to be introduced into the container can be pre-stored or temporarily stored in the storage tank in liquid form and / or in gaseous form. The container can include at least one opening for receiving and / or removing concrete particles. The container further includes an inlet for introducing gas into the container, the inlet being fluid operably connected to the storage tank via a supply line. An inlet valve is used to control the volume flow rate of the gas introduced into the container. The inlet valve can be a proportional valve. The system also includes at least one sensor (as described above) and a control unit operably connected to the at least one sensor and the inlet valve. The sensor is used to determine, via the control unit, the amount of CO2 absorption occurring in the concrete particles in the container. The control unit is designed to control the volume flow rate of the gas through the inlet valve. In addition, the control unit can also be operably connected to a pump. The pump can be located in the supply line or the discharge line of the container. The pump can be a vacuum pump. As described above, the pump can be used to generate a vacuum.

[0033] The control of the volume flow rate is advantageously achieved automatically. According to the above method, the control unit is designed to repeatedly perform the following steps: supply the volume flow rate of the gas containing CO2 according to the amount of CO2 absorption occurring in the concrete particles in the container determined by at least one sensor, and determine whether a predetermined CO2 saturation of the concrete particles has been reached. If the predetermined CO2 saturation of the concrete particles has not been reached, the previous gas supply step can be continued until the predetermined CO2 saturation is reached.

[0034] For effective inflation, the container is advantageously at least partially airtight. Depending on the design of the container, it may include a container base and at least one circumferential sidewall. The at least one circumferential sidewall surrounds the receiving space of the container for receiving concrete particles. For example, the at least one sidewall may be tubular. The tubular sidewall may have a circular or angular cross-section. Advantageously, the base and the at least one sidewall are airtight. According to the present application, the concrete particles can be filled and extracted through a single opening. However, advantageously, the device includes a first opening for filling the concrete particles and a second opening for extracting the concrete particles. For example, a first (upper) opening and a second (lower) opening opposite thereto in the direction of gravity can be provided. In this case, when the second (lower) opening is opened, the concrete particles can automatically fall out of the container. In the present embodiment, in particular, only the second (lower) opening can be designed to be closed in an airtight manner, while the first (upper) opening can remain open. However, embodiments in which both openings can be closed in an airtight manner are also possible. For this purpose, the system may include at least one lid.

[0035] At least one sensor is advantageously arranged in the container. This includes embodiments in which the sensor is arranged on a protrusion, a section of pipe or a similar part on the sidewall and is fluid-operably connected to the receiving space of the container. To determine the amount of CO2 absorbed by the concrete particles, different types of sensors (as described above) can be used. Any combination of one or more of these sensor types is also conceivable. Since CO2 is heavier than air and thus tends to accumulate at the bottom of the container, for example, a plurality of concentration sensors can be arranged one above the other in the container in the direction of gravity.

[0036] To supply CO2 to the container evenly and quickly, the gas inlet may include a plurality of gas inlet nozzles. The gas inlet nozzles can be arranged on the base of the container and / or at least one sidewall, especially in a matrix pattern. It is also conceivable that a plurality of gas inlet nozzles are distributed in the receiving space of the container in a matrix pattern. The gas inlet nozzles can be interconnected by pipelines. Depending on the design of the container, the gas inlet nozzles can also be arranged to be distributed around the receiving space of the container, for example, circumferentially. The container may further include an outlet for discharging gas from the container. In the discharge pipeline operably connected to the outlet, an outlet valve and / or a flow sensor and / or an additional CO2 concentration sensor can be arranged additionally.

[0037] According to the design of the system, the system may also include multiple containers. For example, the aeration of concrete particles can be performed in parallel in multiple containers. Alternatively, the multiple containers can be connected in series. For example, the excess gas in the first container can be introduced into the second container / collection container to repeat the above method. Alternatively, however, it is also conceivable that the excess gas from the first container is at least partially, but in particular completely passively absorbed by the concrete particles arranged in the collection container. Therefore, the second container / collection container can be fluid-operably connected to the discharge pipeline of the first container. Alternatively or additionally, the second container / collection container can also be fluid-operably connected to the storage tank through a separate supply pipeline having a (second) intake valve.

[0038] Embodiments of the system can be used to implement the method according to the present invention. The foregoing embodiments of the method also disclose corresponding design embodiments of the system for implementing the method, and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Aspects of the present invention are explained in more detail with reference to the examples of the embodiments shown in the following figures and the accompanying description. Among them:

[0040] Figure 1 Schematic diagram of the first form of the system for treating concrete particles according to the present invention;

[0041] Figure 2 Schematic diagram of the second form of the system for treating concrete particles according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0042] Figure 1Shows a schematic view of a first form of a system 1 for processing concrete particles 2 according to the present invention. The system 1 includes a storage tank 3 for storing a gas containing CO2 and at least one at least partially airtight container 4, 12. In the illustrated embodiment, there is a first container 4 and a second (collection) container 12. Both containers 4, 12 can be closed in an airtight manner, and each container includes (in the open state) at least one opening (not shown) for filling and / or extracting the concrete particles 2. The first container 4 includes an inlet 5 for introducing gas into the container 4, and the inlet 5 can be fluid operably connected to the storage tank 3 through a supply line 6. The second container 12 is operably connected to a discharge line 14, and the discharge line 14 is operably connected to the outlet 13 of the first container. An inlet valve 7 is arranged in the supply line 6, between the storage tank 3 and the first container 4, for controlling the supply volume flow rate of the gas entering the container 4. The inlet valve 7 can be a proportional valve. The inlet 5 can include a plurality of gas inlet nozzles. For rapid filling, the gas inlet nozzles can be arranged in a matrix-like manner in the receiving space and / or in the base and / or on at least one side wall of the container 4 (not shown). A pump 17 and an outlet valve 18 can be arranged in the pipeline between the first and second containers 4, 12. The pump 17 can be designed to suck gas from the storage tank 3 into the first container 4 (when the inlet valve 7 and the outlet valve 18 are open). For this purpose, the pump 17 can be a vacuum pump. In addition, a CO2 concentration sensor 8 can be arranged in the discharge line of the first container 4 (or respectively in the pipeline between the two containers 4, 12). This is used to monitor how much CO2 is discharged from the container 4.

[0043] Sensors 8, 9, 10 are also arranged in the first container 4. As described above, based on the measured values of these sensors, the amount of CO2 absorption occurring in the concrete particles 2 can be determined. A control unit 11 is used to control the supply of gas according to the amount of CO2 absorption occurring. For this purpose, the sensors 8, 9, 10, the inlet valve 7, the outlet valve 18, and the pump 17 are operably connected to the control unit 11. The inlet valve 7 and / or the outlet valve 18 can include a flow sensor. The control unit 11 can be specifically designed to automatically control the gas supply and / or the gas discharge until a predetermined CO2 saturation of the concrete particles 2 in CO2 is reached.

[0044] In order to initially fill the container 4 with concrete particles 2 with gas, the intake valve 7 and the outlet valve 18 can be opened first. Then, the pump 17 can suck the gas from the storage tank 3 into the container 4. The concentration sensor 8 in the discharge pipeline 14 of the container 4 can monitor the CO2 concentration. When the desired maximum CO2 concentration is reached in the container 4, the outlet valve 18 can be closed. The intake valve 7 can also be closed at least temporarily. The sensors 8, 9, 10 in the container 4 can measure the pressure, CO2 concentration and temperature in the container. The control unit uses the measured values to determine the CO2 absorption amount. Based on the absorption amount, a gas containing CO2 is input into the container, so as to achieve the best and as uniform as possible CO2 saturation or enrichment degree of the concrete particles 2 with CO2. When the predetermined CO2 saturation is reached, the excess gas can be discharged from the first container 4. Advantageously, in the shown case, the excess gas is filled into the collection container 12, and the collection container 12 is also filled with concrete particles 2. In this case, the excess gas can be advantageously completely absorbed by the concrete particles 2 in the collection container 12. This can be monitored in particular by another CO2 concentration sensor 8 arranged in the discharge pipeline of the collection container 12. Alternatively or additionally, the weight difference between the concrete particles 2 before inflation and the CO2-rich concrete particles 2 after inflation can also be determined. A scale 21 can be arranged in the container 4 for measuring the weight or the weight difference.

[0045] Figure 2Shows a schematic view of a second form of the system 1 for treating concrete particles 2 according to the present invention. The system 1 also includes a storage tank 3 for storing a gas containing CO2 and an at least partially airtight container 4. In the illustrated embodiment, the container 4 is open at the top and includes an upper opening 19 for filling the concrete particles 2. A lower opening 20 for extracting the concrete particles is arranged in a first direction (along the direction of gravity) opposite to the upper opening 19. The lower opening 20 is shown to be closed in an airtight manner. The circumferential side wall of the container is arranged between the upper and lower openings 19, 20. Advantageously, the circumferential side wall is also airtight. The cross-section of the circumferential side wall can be circular or angular. After filling the concrete particles 2, the intake valve 7 is opened, and the gas containing CO2 is filled into the container 4 from the bottom up. For this purpose, in the illustrated case, a pump 17 is arranged in the supply line 6. However, other arrangements can also be considered. For the rapid supply of gas, the container 4 advantageously includes circumferentially arranged gas inlet nozzles 15. These gas inlet nozzles can be arranged in the receiving space of the concrete particles 2 in the container 4 and are interconnected by pipelines or surround the receiving space of the container. In the illustrated case, two sets of circumferentially arranged gas inlet nozzles 15 are arranged one above the other in sequence in the first direction. At least one CO2 concentration sensor 8 can be arranged in the container 4. However, advantageously, a plurality of CO2 concentration sensors 8 are distributed in the first direction, and each CO2 concentration sensor is operably connected to the control unit 11. Alternatively or in addition, there may be other sensors, such as sensors for measuring temperature, pressure, or relative humidity. The CO2 concentration sensor 8 is conducive to continuously measuring the CO2 concentration in the container 4. The control unit 11 controls the gas supply according to the specific CO2 absorption amount occurring in the concrete particles 2. The occurring CO2 absorption amount is determined by the control unit 11 through the measurement of the sensor 8, as described in the foregoing method. The occurring CO2 absorption amount can be the difference between the CO2 input into the container 4 and the measured value of the CO2 present in the container 4. According to the amount of CO2 that has been absorbed, a gas containing CO2 can be added to the container 4. This ensures the effective and uniform saturation of the concrete particles 2 in the container 4. The CO2 concentration sensor 8 located at the uppermost position in the direction of gravity can be used to ensure that the predetermined filling degree 16 of the gas in the container 4 is not exceeded. This can prevent the gas from leaking from the top opening 19. In addition, the method can be controlled such that there is always a layer of concrete particles 2 that is thick enough and uncarbonized or only partially carbonized on the surface of the container 4 (facing the first opening 19). This layer can be used as a filter layer to absorb the unwanted rising CO2. When the CO2-rich concrete particles 2 are extracted from the container 4 through the lower opening 20, this layer sinks to the bottom, and for example, when more concrete particles 2 are refilled from above, when the method is repeated, the predetermined CO2 saturation can be provided accordingly.

[0046] Reference numerals

[0047] 1 System

[0048] 2 Concrete particles

[0049] 3 Storage tank

[0050] 4 Container

[0051] 5 Inlet

[0052] 6 Supply pipeline

[0053] 7 Inlet valve

[0054] 8 Concentration sensor

[0055] 9 Pressure sensor

[0056] 10 Temperature sensor

[0057] 11 Control unit

[0058] 12 Collection container

[0059] 13 Outlet

[0060] 14 Discharge pipeline

[0061] 15 Gas inlet nozzle

[0062] 16 Filling level

[0063] 17 Pump

[0064] 18 Outlet valve

[0065] 19 Upper opening

[0066] 20 Lower opening

[0067] 21 Scale

Claims

1. A method for treating concrete particles for subsequent recycling of the concrete particles, comprising the following method steps: a. filling at least partially airtight container (4) with concrete particles (2); b. supplying a volumetric flow rate of a gas containing CO2 into the container (4) based on the amount of CO2 absorption occurring in the concrete particles (2) in the container (4), the occurring amount of CO2 absorption being determined by at least one sensor (8, 9); c. determining whether the concrete particles (2) have reached a predetermined CO2 saturation, otherwise continuing with method step b; d. removing the CO2 - rich concrete particles (2).

2. The method according to claim 1, wherein The gas input into the container (4) contains 95% to 100% CO2.

3. The method according to any one of the preceding claims, characterized in that, The occurring amount of CO2 absorption is determined by measuring pressure and / or CO2 concentration by at least one sensor (8, 9, 10).

4. The method according to claim 3, wherein The occurring amount of CO2 absorption also takes into account the measured temperature and / or measured weight and / or measured relative humidity in the container (4).

5. The method according to claim 1 or 2, characterized in that, When a desired gas filling level (16) is reached in the container (4) and / or a predetermined CO2 concentration in the container, the volumetric flow rate of the supplied gas is reduced or temporarily interrupted.

6. The method according to claim 5, wherein The reduced or temporarily interrupted volumetric flow rate of the gas containing CO2 compensates for the CO2 absorbed by the concrete particles arranged in the container.

7. The method according to claim 1 or 2 above, characterized in that, When the change in the occurring amount of CO2 absorption is below a limit value within a predetermined time interval, the concrete particles (2) reach the predetermined CO2 saturation.

8. The method according to claim 1 or 2 above, characterized in that, After reaching the predetermined CO2 saturation, the excess gas is introduced from the container (4) into a collection container (12) filled with additional concrete particles (2), and the additional concrete particles absorb at least partially.

9. The method according to claim 8, wherein The method steps b to d are repeated in the collection container (12).

10. Concrete particles (2) produced by the method according to any one of claims 1 to 9, wherein the CO2 saturation of the concrete particles is at least 5 kg CO2 absorbed per 1000 kg.

11. A concrete, which comprises the concrete particles (2) according to claim 10.

12. A system (1) for treating concrete particles (2) for subsequent recycling of the concrete particles (2), comprising a. at least partially airtight container (4), having i. at least one opening (19, 20) for filling and / or extracting the concrete particles (2), and ii. an air inlet (5) for supplying a gas containing CO2 into the container (4), the air inlet being fluid - operably connected to a storage tank (3) through a supply line (6), and b. an inlet valve (7) for controlling the volumetric flow rate of the gas entering the container (4); c. at least one sensor (8, 9, 10) for determining the amount of CO2 absorption occurring in the concrete particles (2) in the container (4); and d. A control unit (11) operatively connected to the at least one sensor (8, 9, 10) and the intake valve (7) and designed to control the volume flow rate supplied through the intake valve (7); The control unit (11) is designed to automatically implement the steps in the following sequence: a. Supply a volume flow rate of the gas containing CO2 into the container (4) according to the amount of CO2 absorption occurring in the concrete particles (2) in the container (4) determined by the at least one sensor (8, 9); b. Determine whether the concrete particles (2) have reached a predetermined CO2 saturation.

13. The system (1) according to claim 12, characterized in that, At least one sensor (8, 9) is arranged in the container (4) and is a pressure sensor (9) for measuring pressure and / or a concentration sensor (8) for measuring the CO2 concentration.

14. The system (1) according to claim 13, characterized in that, A plurality of concentration sensors (8) are arranged one above the other in sequence in the container (4) along the direction of gravity.

15. The system (1) according to any one of the preceding claims 12 to 14, characterized in that, The intake port (5) includes a plurality of gas inlet nozzles (15) arranged in a matrix pattern in the receiving space of the container (4) and / or on at least one side wall of the container (4) and / or on the base of the container (4).

16. The system (1) according to any one of the preceding claims 12 to 14, characterized in that, The system (1) includes a collection container (12) for receiving more concrete particles (2), and the collection container is fluid operatively connected to the container (4) through the discharge pipeline (14) of the container (4).

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