ATIVAÇÃO MECANOQUÍMICA E TÉRMICA COMBINADA DE ARGILAS

Abstract

The present invention relates to a method for the combined thermal and mechanochemical activation of mineral material, the method comprising the following steps: a) crushing and drying the mineral material, b) grinding and mechanochemically activating in a first high-energy mill (40), and thermally activating in a thermal treatment device (90), with step b) being carried out before step c) or step c) before step b).

Description

1 / 19 Combined Mechanochemical and Thermal Activation of Clays

[001] The present invention relates to a method for the combined mechanochemical and thermal activation of clays.

[002] Activated clays have established themselves as additives, particularly in the cement industry. Currently, the common method is drying and calcining the clays, that is, thermal activation.

[003] This requires energy for heating on the one hand, and on the other hand, the high temperature can also cause other material changes that may be undesirable. In addition, the thermal method requires cleaning the combustion gas to separate the resulting emissions of nitrogen oxide and sulfur oxide. Furthermore, in the future, the thermal method will require the use of methods for separating and, if necessary, purifying the carbon dioxide that is produced and released.

[004] Document no. WO 2017 / 008 863 A1 discloses a method and plant arrangement for processing and activating a raw material.

[005] Document No. EP 3 909 682 A1 discloses a method and rolling cylinder for thermomechanical activation of a clay mixture.

[006] Document No. DE 10 2015 106 109 A1 discloses a method for tribochemical activation of ligands and additives.

[007] Document No. RU 2 209 824 C2 reveals a Petition 870250081178, dated 10 / 09 / 2025, pp. 50 / 103 2 / 19 method for producing fluid paste powders.

[008] Document No. US 2011 / 233314 A1 discloses a method of grinding.

[009] Document No. RU 2 209 824 C2 discloses a method for producing fluid paste powders.

[0010] Document No. US 2011 / 233314 A1 discloses a method of grinding.

[0011] TOLE ILDA ET AL: Mechanochemical activation of natural clay minerals: an alternative for the production of sustainable cementitious binders - Review”, MINERALOGY AND PETROLOGY, SPRINGER VIENNA, VIENNA, volume 113, no. 4, May 8, 2019 (08 / 05 / 2019), pages 449-462, XP036833323, ISSN: 0930-0708, DOI: 10.1007 / S00710-019-00666-Y [found on May 8, 2019] reveal the mechanochemical activation of clays.

[0012] Since clays constitute a complex system (especially when compared to limestone firing), different activation methods generate different products (activated clays) with different properties. Similarly, because there are several usable clays, this means that not every method can be used for every clay.

[0013] The objective of the invention is to provide an alternative activation method so that other qualities of clay can be used in addition to those that are considered Petition 870250081178, dated 10 / 09 / 2025, pp. 51 / 103 3 / 19 currently as suitable for clay calcination or for obtaining other product properties. Specifically, it should be possible to extend the raw material base to muscovite, illitic or chlorite clays.

[0014] The objective is achieved by the method with the resources disclosed in claim 1. Advantageous embodiments result from the dependent claims, the following description, and the drawings.

[0015] The method according to the invention is used for the combined thermal and mechanochemical activation of mineral material. The method has the following steps: a) drying and coarse fragmentation of the mineral material, b) dry grinding and mechanochemical activation in a first high-energy mill, and c) thermal activation in a heat treatment device.

[0016] Step b) is performed before step c) or step c) is performed before step b).

[0017] In step a), an initial drying and coarse fragmentation occur. In the present context, the sequence of drying and coarse fragmentation may be arbitrary; they may also occur (partially) simultaneously. This is well known to those skilled in the art. Ultrafine mills, i.e., mills that can produce a size Petition 870250081178, dated 10 / 09 / 2025, pp. 52 / 103 4 / 19 of particularly small particle size, they generally cannot be operated with very coarse material. On the other hand, ultrafine mills are optimized for ultrafine grinding and are therefore unsuitable and uneconomical for coarse fragmentation. Therefore, it is common and sensible to perform coarse fragmentation before the material is fed into an ultrafine mill. Another main application is the activation of clays, but also of slag stored in piles, for example. For this reason, the initial moisture content of the starting materials is usually very high to the point that drying is necessary. Both situations are common before conventional thermal activation and can be carried out analogously.

[0018] In this case, the grinding is carried out without the addition of water, that is, it is not wet nor does it occur in a fluid paste, but rather as dry grinding without the addition of moisture in accordance with the drying in step a), which distinguishes it from the classic wet grinding method.

[0019] Depending on the energy input, three stages can be observed in the grinding of a material. In the first stage, the particle size decreases (more or less linearly) in relation to the energy input. Simply put, the more it is ground, the finer the product will be. However, there is a Petition 870250081178, dated 10 / 09 / 2025, pp. 53 / 103 5 / 19 limit, a particle size below which it is almost impossible to reach (Rttinger zone). After this point, a second stage is reached in which the particle size does not change without additional energy input. For economic reasons, the transition from the first stage to the second stage is therefore avoided during normal grinding, since additional tastes do not generate any observable additional grinding effect (aggregation zone). If the energy input is increased further, it is possible to reach a third stage in which an increase in particle size can again be observed (agglomeration zone). Therefore, this zone is much more likely to be avoided during normal grinding, as a better result can be obtained with less expenditure.

[0020] However, it turned out that high energy inputs, i.e., in the second stage, caused changes in the material itself, which, in the case of clays, for example, as well as thermal activation, caused an activation, i.e., a reactivity that enables the use of a binder (and, consequently, as a substitute for clinker). Therefore, with such high energy inputs, dispensing is possible to the maximum extent with subsequent heat treatment.

[0021] However, in this case, it turned out that the energy requirements for a purely automatic activation Petition 870250081178, dated 10 / 09 / 2025, pp. 54 / 103 6 / 19 mechanochemical requirements may be higher for thermal activation. Therefore, the method according to the invention, in principle, appears to be disadvantageous compared to conventional purely thermal activation. However, despite the potentially high energy requirements, in comparison, the method according to the invention proves to be advantageous, specifically for the activation of clays.

[0022] However, in this case, there is a difference in the finished product between mechanochemical activation and thermal activation, which is difficult to detect due to the very complex material and the very local modification during activation, but which manifests itself, for example, in certain differences in hardening behavior. Therefore, it can be assumed that the two different activation methods either activate different centers or activate them in different ways. Thus, the combination makes it possible to obtain a new binder. Therefore, according to the invention, the two activation methods are combined with each other. In the present context, it is essential that the mechanochemical activation in step b) is not merely a grinding process to reduce particle size, but rather that an actual activation of the material occurs.Furthermore, it is also essential that, during the combination of mechanochemical activation with thermal activation, the thermal activation substep can be carried out at significantly lower temperatures. Petition 870250081178, dated 10 / 09 / 2025, pp. 55 / 103 7 / 19 comparison to the case with thermal activation only.

[0023] In a further embodiment of the invention, thermal activation is carried out at a temperature lower than 600 °C, preferably lower than 500 °C. In purely thermal activation, temperatures of 850 °C or higher are common. This saves energy and thus at least partially reduces the energy requirements for mechanochemical activation. On the other hand, however, reducing the maximum temperature also has other positive effects, such as a reduction in the thermal formation of nitrogen oxides or the prevention of undesirable product changes, for example, color changes due to the oxidation of coloring components.

[0024] In a further embodiment of the invention, the mechanochemical activation of the mineral material in step b) causes an increase in the R3 value (7d) according to ASTM C189720 of at least 150 J / g, preferably at least 250 J / g. The activation is then high enough to allow activated materials to be used as complementary cementitious materials (SCM). The ASTM C1897-20 standard is the most widely used standard in the cement industry for testing reactivity and hardening component.

[0025] According to the invention, the mechanochemical activation of the mineral material in step b) causes an increase in the R3 value (7d) according to ASTM C1897-20 of Petition 870250081178, dated 10 / 09 / 2025, pp. 56 / 103 8 / 19 at least 25%, preferably at least 33%, of the total activation of steps b) and c). This means that at least 1 / 4, preferably at least 1 / 3 of the total activation (increased reactivity) is attributable to mechanochemical activation. If, for example, the total increase in activity through mechanochemical and thermal activation was 400 J / g, and the proportion of this increase attributable to mechanochemical activation was 200 J / g, then the proportion would have been 50%. This value can be easily determined by recording a first measurement of the R3 value between steps b) and c) (regardless of the sequence) and a second measurement of the R3 value after steps b) and c) (i.e., after complete activation).

[0026] In a further embodiment of the invention, thermal activation is performed first in step c) and then mechanochemical activation is performed in step b). This allows color optimization to be performed during mechanochemical activation in step b) in order to neutralize unwanted discoloration caused by thermal activation in step c). For this reason, grinding and mechanochemical activation in step b) are performed in such a way that the mineral material is ground together with a reducing agent in the first high-energy mill. A metal with an electronegativity less than 1.8, preferably less than 1.7, can be selected as the reducing agent. Petition 870250081178, dated 10 / 09 / 2025, pp. 57 / 103 9 / 19 Alternatively, a hydrocarbon, preferably a gaseous hydrocarbon, most preferably propane, may be selected as the reducing agent.

[0027] In a further embodiment of the invention, the mechanochemical activation in step b) is carried out with an energy input per grinding chamber volume of at least 100 kW / m3, preferably at least 200 kW / m3. A typical value for a ball mill, for example, an ultrafine mill is normally closer to 20 kW / m3e, and is therefore significantly lower (and more energy efficient). In this connection, the grinding chamber volume is understood to be the available volume inside the first high-energy mill, i.e., the free volume when there is no material and, for example, no balls in the first high-energy mill. Components belonging to the mill, for example, a shaft that is movably arranged inside, are therefore not part of the grinding chamber volume since this volume cannot be occupied by the material.

[0028] In a first embodiment of the invention, mechanochemical activation occurs in step b) before thermal activation in step c). The advantage here is that the mechanochemical activation, which goes beyond simple grinding and consequently a reduction in particle size, already achieves activation and, consequently, a change in Petition 870250081178, dated 10 / 09 / 2025, pp. 58 / 103 10 / 19 local level of the material. This, in turn, significantly simplifies subsequent thermal activation. It can be assumed, for example, that “predetermined rupture points are produced in the material during mechanochemical activation so that thermal activation can be carried out at a considerably low cost, specifically, at significantly lower temperatures.

[0029] In a second embodiment of the invention, the mechanochemical activation in step b) occurs after the thermal activation in step c). The advantage here is that the prior thermal activation, and in particular the gaseous products produced during this process, generates a material that is easier to grind, which in turn can then be more easily transferred to the second stage (activation during the grinding process) so that the residence time and therefore the energy input per unit of product are shorter. At the same time, these product binding properties are more similar to those of the mechanochemically activated ligand, since no change occurs after the mechanochemical activation.

[0030] In a further embodiment of the invention, the first high-energy mill is operated continuously. This means that the first high-energy mill is Petition 870250081178, dated 10 / 09 / 2025, pp. 59 / 103 11 / 19 continuously fed with mineral material and, at the same time, the activated mineral material is continuously removed. Preferably, the first high-energy mill is therefore operated as a continuous mill with an inlet side and an outlet side.

[0031] In a further embodiment of the invention, the first high-energy mill is selected from the group comprising vibratory mills, planetary ball mills and agitator-type ball mills. Preferably, the first high-energy mill is selected from the group comprising planetary ball mills and agitator-type ball mills. These types of mills have proven to be particularly suitable for mechanochemical activation, as these types of mills can introduce particularly high energy densities. It is particularly preferable to use a dry-operated agitator-type ball mill as the first high-energy mill.

[0032] In a further embodiment of the invention, a stirrer-type microsphere mill with a length-to-diameter ratio of 2.5 to 5 is selected.

[0033] In a further embodiment of the invention, the first high-energy mill is loaded with a grinding media loading level of 50% by volume to 95% by volume, preferably 60% by volume to 70% by volume. Petition 870250081178, dated 10 / 09 / 2025, pp. 60 / 103 12 / 19 volume. In the present context, the apparent volume of the crushing media refers to the volume of the first high-energy mill. Since the loading level is approximately 64% with simple packing and approximately 74% with denser sphere compaction, even a theoretical crushing media loading level of 100% generates a corresponding free space, which can be occupied by the mineral material to be activated, for example. However, since the loading level of a crushing media packing is highly dependent on the shape and uniformity of the crushing media, it is simpler, from a practical point of view, for the crushing media loading level to be related to apparent volume and not to the actual (loaded) volume.

[0034] In a further embodiment of the invention, grinding media produced from iron or an iron alloy or grinding media produced from aluminum or an aluminum alloy are selected. Preferably, grinding media produced from iron or an iron alloy are selected. Specifically, grinding media produced from steel are selected.

[0035] In a further embodiment of the invention, ceramic grinding media are selected.

[0036] In a further embodiment of the invention, the Petition 870250081178, dated 10 / 09 / 2025, pp. 61 / 103 13 / 19 grinding media with a diameter of 1 mm to 10 mm are selected.

[0037] In a further embodiment of the invention, the agitator-type microsphere mill is operated at a peripheral speed of 2 m / s ≈ 6 m / s; preferably, 3 m / s ≈ 5 m / s; with specific preference, 3.5 m / s ≈ 4.5 m / s.

[0038] In a further embodiment of the invention, the agitator-type microsphere mill is operated with a gas volume flow and a material flow. The ratio between gas volume flow and material flow is defined such that the ratio between gas volume flow and material flow is between 0.0001 m3 / kg and 5 m3 / kg, preferably between 0.1 m3 / kg and 2 m3 / kg.

[0039] In a further embodiment of the invention, the drying and fragmentation in step a) is carried out until a residual moisture content of less than 1% by weight and a particle size of less than 2 mm is achieved.

[0040] In a further embodiment of the invention, the mineral material is selected from the group comprising clay, ash, specifically fly ash, lime cement clinker, spent concrete fines, slag, sheet silicates and silicates in structures. A particularly preferred mineral material is clay or a mixture of clay and one or more additional materials. Petition 870250081178, dated 10 / 09 / 2025, pp. 62 / 103 14 / 19 selected from the group comprising ash, specifically fly ash, lime cement clinker, spent concrete fines, slag, sheet silicates and silicates in structures.

[0041] In a further embodiment of the invention, the mineral material is activated mechanochemically together with 0.1-50% by weight of quartz or corundum.

[0042] In a further embodiment of the invention, after removal of the activated mineral material, the activated material is analyzed to determine the activation. This can be done either after only one activation step (mechanical or thermal) or after both activation steps. It is preferable to do this at both points so that the activation can be determined at both consecutive steps. This allows both activation steps to be optimized. For the analysis, one or more methods are selected from the group comprising IR spectroscopy, Raman spectroscopy, X-ray diffraction analysis, heat flow calorimetry, thermogravimetry, scanning electron microscopy, particle size and / or shape analysis, and NMR spectroscopy. One or more methods selected from the group comprising IR spectroscopy, Raman spectroscopy, X-ray diffraction analysis, and heat flow calorimetry are particularly preferred for the analysis. Petition 870250081178, dated 10 / 09 / 2025, pages 63 / 103 15 / 19

[0043] In a further embodiment of the invention, the gas selected and used for the gas flow through the first high-energy mill is a gas comprising one or more gases selected from the group comprising nitrogen, argon, carbon dioxide, water vapor, carbon monoxide, hydrogen and hydrocarbons, in particular methane, ethane, propane and butane. Preferably, the gas comprises mainly (more than 50% by volume) nitrogen, carbon dioxide or water vapor. Preferably, the gas comprises less than 1% by volume, preferably less than 0.1% by volume, of oxygen.

[0044] In a further embodiment of the invention, the mineral material is crushed with a liquid or solid reducing agent in step b). For example, coal or coal powder can be used as a solid reducing agent. For example, a liquid hydrocarbon can be used as a liquid reducing agent. On the one hand, the addition serves to prevent, for example, iron oxidation. At the same time, it can be used to obtain a desired neutral gray shade of the finished product.

[0045] In a further embodiment of the invention, the grinding in step b) is carried out at a material temperature of 100 °C to 250 °C. This elevated temperature is advantageous to avoid water condensation and, if Petition 870250081178, dated 10 / 09 / 2025, pp. 64 / 103 16 / 19 necessary, remove additional water. In particular, if thermal activation in step c) occurs before mechanochemical activation in step b), then this can already be achieved by the temperature at which the material is introduced.

[0046] In a further embodiment of the invention, after mechanochemical activation in step b), the activated mineral material is separated into a first fraction and a second fraction; wherein the first fraction returns for further mechanochemical activation in step b). The second fraction is removed as a product (if thermal activation in step c) was performed before mechanochemical activation in step b)) or is provided for thermal activation in step c) (if thermal activation in step c) was performed after mechanochemical activation in step b)).

[0047] In a further embodiment of the invention, the thermal activation in step c) is carried out in a entrained flow reactor or in a rotary kiln. Preferably, an entrained flow reactor is used.

[0048] In a further aspect, the invention relates to a binder that is produced according to the method of the invention.

[0049] The method according to the invention will be explained in more detail below with reference to the exemplary embodiments in the drawings. Petition 870250081178, dated 10 / 09 / 2025, pages 65 / 103 17 / 19

[0050] Figure 1 is the first example flow.

[0051] Figure 2 is the second example flowchart.

[0052] A very schematic illustration of a first method is shown in Figure 1 based on an exemplary first flowchart. For example, the hammer mill 10 is fed with clay, which is fragmented and transported in a starting material silo 30 by means of an ascending tube dryer 20. The then pre-fragmented and dried clay is transferred to a first high-energy mill 40 (a dry-operated microsphere mill with a grinding media loading level of 65% — using steel spheres with a diameter of 4 mm as grinding media). The energy input is 350 kW / m3. The agitator-type microsphere mill has a length-to-diameter ratio of 4 and is operated at a peripheral speed of 4 m / s. The gas volume flow rate to material flow rate ratio is 0.01 m3 / kg. The material obtained from the first high-energy mill 40 is separated in a separator 50.The fine material is transported back to the inlet of the first high-energy mill 40 and the coarse activated material is transferred to a heat treatment device 90, preferably a entrained flow reactor, where it is thermally activated at 450 °C, by. Petition 870250081178, dated 10 / 09 / 2025, pp. 66 / 103 18 / 19 example. Next, the finished product can be removed from the heat treatment device 90 and transferred to a product silo 60.

[0053] Figure 2 shows a second alternative method using an exemplary first flowchart. The difference from the first method shown in Figure 1 is that thermal activation occurs before mechanochemical activation. For example, the hammer mill 10 is fed with clay, which is fragmented and conveyed through an ascending tube dryer 20 into a starting material silo 30. The clay that has been pre-fragmented and dried in this way is transferred to a heat treatment device 90, preferably a entrained flow reactor, and thermally activated at 450 °C. Then, the partially activated clay is transferred to a first high-energy mill 40 (a dry-operated agitator-type ball mill with a grinding media loading degree of 65%, using 4 mm diameter balls as grinding media). The energy input is 350 kW / m3.The agitator-type microsphere mill has a length-to-diameter ratio of 4 and is operated at a peripheral speed of 4 m / s. The gas volume flow rate to material flow rate ratio is 0.01 m³ / kg. The material removed from the first high-energy mill 40 is separated in a separator 50. The fine material is... Petition 870250081178, dated 10 / 09 / 2025, pp. 67 / 103 19 / 19 transported back to the inlet of the first high-energy mill 40, and the activated coarse material is transferred to a product silo 60. Numerical References

[0054] 10 hammer mill rising tube dryer starting material silo first high-energy mill separator product silo heat treatment device Petition 870250081178, dated 10 / 09 / 2025, pages 68 / 103

Claims

1 / 4 CLAIMS 1. Method for combined thermal and mechanochemical activation of mineral material, the method comprising the following steps: drying and coarse fragmentation of the mineral material, dry grinding and mechanochemical activation in a first high-energy mill (40), and thermal activation in a heat treatment device (90), wherein step b) is performed before step c) or step c) is performed before step b), characterized in that the mechanochemical activation of the mineral material in step b) causes an increase in the R3 value (7d) according to ASTM C1897-20 in at least 25% of the total activation of steps b) and c).

2. Method, according to claim 1, characterized in that the thermal activation is carried out at a temperature lower than 600 °C, preferably lower than 500 °C.

3. Method, according to any of the claims, characterized in that the mechanochemical activation of the mineral material in step b) causes an increase in the R3 (7d) value according to ASTM C1897-20 by at least 150 J / g, preferably by at least 250 J / g.

4. Method, according to any of the preceding claims, characterized in that the mechanochemical activation of the mineral material in step b) causes an increase in the R3 value (7d) according to ASTM C1897-20 by at least 33% of the total activation of steps b) and c).

5. A method, according to any of the preceding claims, characterized in that the mechanochemical activation of the mineral material in step b) is carried out with an energy input per mill volume of at least 100 kW / m3, preferably at least 200 kW / m3.

6. Method, according to any of the preceding claims, characterized in that the first high-energy mill (40) is operated continuously.

7. Method, according to any of the preceding claims, characterized in that the first high-energy mill (40) is selected from the group comprising vibrating mills, planetary ball mills and agitator-type ball mills.

8. Method, according to any of the preceding claims, characterized in that the first high-energy mill (40) is a dry-operated agitator-type ball mill.

9. Method, according to any of the preceding claims, characterized in that a stirrer-type microsphere mill with a length-to-diameter ratio of 2.5 to 5 is selected.

10. Method, according to any of the preceding claims, characterized in that the first high-energy mill (40) is filled with a grinding media loading level of 50% by volume to 95% by volume, preferably 60% by volume to 70% by volume; wherein the apparent volume of the grinding media refers to the volume of the first high-energy mill (40).

11. A method, according to any of the preceding claims, characterized in that the agitator-type microsphere mill is operated at a peripheral speed of 2 m / s ± 6 m / s, preferably 3 m / s ± 5 m / s, with particular preference for 3.5 m / s ± 4.5 m / s.

12. Method, according to any of the preceding claims, characterized in that the agitator-type microsphere mill is operated with a gas volume flow and a material flow; wherein the ratio between the gas volume flow and the material flow is defined so that the ratio between the gas volume flow and the material flow is between 0.0001 m3 / kg and 5 m3 / kg, preferably between 0.1 m3 / kg and 2 m3 / kg.

13. Method, according to any of the preceding claims, characterized in that the drying and fragmentation in step a) are carried out with a residual moisture content of less than 1% by weight and with a particle size of less than 2 mm.

14. A method, according to any of the preceding claims, characterized in that the mineral material is selected from the group comprising clay, ash, specifically fly ash, lime cement clinker, used concrete fines, slag, sheet silicates and structural silicates.

15. A method, according to any of the preceding claims, characterized in that after mechanochemical activation in step b), the activated mineral material is separated into a first fraction and a second fraction in step e), wherein the first fraction is returned for further mechanochemical activation in step b), and the second fraction is removed as a product or is provided for thermal activation in step c).

16. Method, according to any of the preceding claims, characterized in that the thermal activation in step c) is carried out in a entrained flow reactor or in a rotary kiln. Petition 870250081178, dated 10 / 09 / 2025, pp. 91 / 103

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