DE102023100032A1 - Hydrothermally produced materials and their production and use - Google Patents

Abstract

The invention relates to a hydrothermally produced composition comprising tobermorite and/or another calcium silicate hydrate phase, the composition having a large number of pores and comprising at least one substance selected from a group comprising quartz sand, gravel, crushed sand, fine white lime, grey lime, cement, quicklime, anhydride/gypsum, aluminium and quartz powder, each of these substances having a purity of ≥ 90%. The invention further relates to a method for producing a porous composition and applications for such a composition.

Description

The present invention relates to a hydrothermally produced composition comprising tobermorite and/or another calcium silicate hydrate phase. Furthermore, the invention relates to a process for producing such a composition and applications of such a composition.

From the state of the art, sand-lime brick, aerated concrete and mineral insulation boards are known as a group of building materials with a very similar chemical basis but surprisingly different application properties. What these building materials have in common is that they contain a synthetic form of the naturally occurring mineral tobermorite and/or another calcium silicate hydrate phase (also known as C-S-H phase) as an essential component.

However, these building materials differ fundamentally in some properties. For example, sand-lime brick has a comparatively high density because it is heavily compacted during the manufacturing process, so that the product is a material with a high bulk density. Sand-lime brick has a compressive strength of up to 35 N/mm ² . It is characterized by, among other things, high sound insulation.

In contrast to sand-lime bricks, components made of aerated concrete are expanded during production. This results in a product with a high pore content and low bulk density. Aerated concrete components are characterized by very good thermal insulation, among other things.

Mineral insulation boards are produced by even greater expansion and therefore have an even lower density and an even higher thermal insulation property than aerated concrete.

To produce sand-lime brick, the components are weighed and mixed, water is added and, after intermediate storage and if necessary, further water is added, the brick is pressed into the desired shape (e.g. stone) using presses. These molded parts are then hydrothermally hardened in an autoclave at approx. 200°C at 14-16 bar within 4-8 hours. C-S-H phases, predominantly tobermorite, form at the interface between hydrated lime and quartz.

When producing aerated concrete, the components are also mixed and the quicklime it contains is slaked by adding water. The mixture is poured into molds. Since the mixture also contains aluminum powder, this reacts in an alkaline environment to form hydrogen. When this gas is released, it increases in volume and creates bubbles that remain in the product as pores. During the reaction, the mixture expands to up to 90% of its original volume within 20 - 50 minutes. The pore size is usually around 0.5 - 1.5 mm. The molded parts produced in this way are then also autoclaved, but at around 180 - 200° C and 10-12 bar for a period of 6 - 12 hours. Here, too, CSH phases, predominantly tobermorite, form during hardening. The molded parts usually have a bulk density of 300 - 650 kg/m ³ .

Mineral insulation boards are manufactured using a composition similar to that used to manufacture aerated concrete, but with a higher aluminum content. Accordingly, more gaseous hydrogen can be formed in an alkaline environment, which leads to an even greater increase in volume and thus an even lower bulk density of the product, usually only 85 - 115 kg/m ^3. The proportion of air pores in the product can reach up to 95%.

The classes of building materials described above can be produced relatively sustainably because, for example, the raw materials used can be sourced regionally. Emissions from their transport can therefore be kept to a minimum. This can be justified in particular by the fact that the raw materials used are basic materials that are more or less available everywhere and do not require complex finishing processes to produce.

What the above-mentioned classes of building materials have in common is that only a relatively low pressure and a relatively low temperature are required during their production during curing. The thermal energy required is usually provided in the form of steam. This type of curing is also known as a hydrothermal curing process. The steam used can be recovered, which can further reduce the use of materials and energy.

Materials which harden according to such a process involving water vapor as a reactant and energy carrier are referred to in this invention as hydrothermally produced materials.

In the past, products made from the above-mentioned hydrothermally produced materials were used exclusively in construction applications. The composition of the manufactured products has long been established and unchanged. Significant changes to the products in recent years have only been a change in their shape.

Accordingly, the products can be used almost exclusively in the applications described, namely as a component of the masonry in the form of stones or slabs.

The recyclability of these materials is very limited. In the past, recipes have been presented that are intended to eliminate this disadvantage. For example, in EP 3 235 794 B1 a recipe for a low-sulfate aerated concrete is described. This recipe has improved leaching behavior, so that the sulfate concentration in the eluate is low.

There is therefore a need to provide hydrothermally produced materials in completely different forms, which deviate from the stone or plate form, in order to make these materials accessible for other applications.

Furthermore, it is an object of the invention to provide a process for producing such materials and to demonstrate new application possibilities.

This problem is solved by the subject matter of the independent patent claims. Further developments and preferred embodiments are the subject matter of the dependent patent claims.

A solution to the underlying problem therefore consists in a hydrothermally produced composition comprising tobermorite and/or another calcium silicate hydrate phase. This composition has a large number of pores and comprises a substance, preferably several substances, which is/are selected from a group comprising quartz sand, gravel, crushed sand, fine white lime, grey lime, cement, quicklime, anhydride/gypsum, aluminium and quartz powder, each of these substances having a purity ≥ 90%.

The composition preferably comprises at least 2, preferably 3 of the aforementioned substances. Each of these substances preferably has the above-mentioned purity of ≥ 90%. As is usual for purity information, these details refer to percent by mass. Unless otherwise stated in the context of this invention, all percentages are to be understood as percent by mass.

The high purity of the substance(s) used makes it possible to avoid contamination of the product. In a preferred embodiment, the composition can have a whiteness R457 ≥ 70, preferably ≥ 75, more preferably ≥ 78, further preferably ≥ 80, most preferably ≥ 81. This enables the composition to be used in areas where white products are required. In addition, it is also possible to adjust the color in a targeted manner, for example by adding pigments. Any distortion of the desired color due to contamination can thus also be minimized.

Preferably, the composition is particularly low in impurities from coloring elements such as Fe, Cr, Cu, Ni, Co, Ti and Mn. Preferably, the proportion of the elements Fe, Cr, Cu, Ni, Co, Ti and Mn (measured as their oxide form, for example by quantitative element analysis using atomic absorption spectroscopy, atomic emission spectroscopy or inductively coupled plasmas coupled with optical emission spectroscopy (ICP-OES)) in the composition is ≤ 1 mass percent, preferably ≤ 0.75 mass percent, more preferably ≤ 0.5 mass percent, further preferably ≤ 0.25 mass percent, most preferably ≤ 0.1 mass percent.

In a preferred embodiment, the composition comprises at least one substance selected from a group comprising amorphous SiO ₂ , white cement, partially calcined dolomite, fully calcined dolomite, magnesite (preferably caustic), fibers, porosity agents, recycled material preferably based on sand-lime brick, aerated concrete or mineral insulation boards, pigments, binders, preferably inorganic or organic binders, particularly preferably water glass, phosphate binders, latex, cellulo based binders, acrylate or styrene and amorphous substances, preferably glass (crushed or round), kieselguhr, diatomite or partially calcined kaolin. By adding one or more of these substances, the composition can be given a different property profile so that the composition can be adapted or optimized for specific applications.

The composition preferably comprises the substance and/or the substances which are selected from a group comprising quartz sand, gravel, crushed sand, fine white lime, grey lime, cement, quicklime, anhydride/gypsum, aluminium and quartz powder, each of these substances preferably having a purity of ≥ 92%, preferably ≥ 95%. As a result, the quality of the composition can be significantly influenced when selecting the substances used and increased to such an extent that the composition can be used in applications which have high quality requirements.

In a preferred embodiment, the composition is in particulate form. The average particle size (sieve analysis) is ≤ 80 mm, preferably ≤ 50 mm, further preferably ≤ 25 mm, more preferably ≤ 10 mm, particularly preferably ≤ 5 mm.

In another preferred embodiment, the average particle size (sieve analysis or Sedigraph) is significantly smaller and is preferably ≤ 2 mm, preferably ≤ 1 mm, further preferably ≤ 750 µm, more preferably ≤ 500 µm, particularly preferably ≤ 250 µm. This opens up further applications, for example as (a carrier for a) catalyst or filler.

• - Bereitstellen eines ersten Rohstoffs oder mehrerer Rohstoffe mit einer Reinheit ≥ 90 %, wobei der Rohstoff/die Rohstoffe ausgewählt ist/sind aus einer Gruppe, die Quarzsand, Kies, Brechsand, Weißfeinkalk, Graukalk, Zement, Branntkalk, Anhydrid/Gips, Aluminium und Quarzmehl umfasst,
• - Vermischen der Rohstoffe,
• - hydrothermale Umsetzung der Rohstoffmischung zu der Zusammensetzung durch Beaufschlagung mit Wasserdampf.

In terms of the process, the object described above is achieved by a process for producing a porous composition, which comprises the steps:

• - Providing a first raw material or several raw materials with a purity ≥ 90 %, wherein the raw material(s) is/are selected from a group comprising quartz sand, gravel, crushed sand, fine white lime, grey lime, cement, quicklime, anhydride/gypsum, aluminium and quartz powder,
• - Mixing of raw materials,
• - hydrothermal conversion of the raw material mixture to the composition by exposure to water vapor.

This process makes it particularly easy to produce a composition as described above cost-effectively and in large quantities.

The process is particularly suitable for producing such a composition with only low CO ₂ emissions or even completely without CO ₂ emissions. In this regard, it would be conceivable, for example, to use renewably obtained C-containing energy sources or with renewably generated electricity or to generate them using geothermal energy. In particular, the use of renewably generated electricity as the sole form of energy for heat generation offers a highly interesting alternative to C-containing energy sources, particularly with regard to CO ₂ emissions and the associated requirements and efforts to reduce them. In a preferred process variant, the steam used for the hydrothermal conversion is therefore preferably generated from water using electricity, in particular electricity from renewable sources.

In a preferred process variant, at least one second raw material, preferably several second raw materials, is used to produce the raw material mixture. The at least one second raw material is selected from a group that includes amorphous SiO ₂ , white cement, partially calcined dolomite, fully calcined dolomite, magnesite (preferably caustic), fibers, porosity agents, recycled material preferably based on sand-lime brick, aerated concrete or mineral insulation boards, pigments, binders, preferably inorganic or organic binders, particularly preferably water glass, phosphate binders, latex, cellulose-based binders, acrylate or styrene and amorphous substances, preferably glass (broken or round), diatomaceous earth, diatomite or partially calcined kaolin. It has been shown that by adding one or more raw materials from this group, the hydrothermally produced composition can be given new properties that make these compositions with modified properties suitable for new applications.

Preferably, the proportion of the elements Fe, Cr, Cu, Ni, Co, Ti and Mn measured as their oxide form in the at least one first and/or the at least one second raw material, preferably in each of the raw materials used, is ≤ 1 mass percent, preferably ≤ 0.75 mass percent, more preferably ≤ 0.5 percent by mass, more preferably ≤ 0.25 percent by mass, most preferably ≤ 0.1 percent by mass. This selection of raw materials makes it possible to specify the properties of the hydrothermally produced composition and, in particular, to prevent undesirable discoloration from occurring in the composition.

In a preferred embodiment, tobermorite and/or another calcium silicate hydrate phase is formed during the hydrothermal conversion of the raw material mixture. It is particularly preferred that a large number of pores are formed in the resulting product by exposure to water vapor. These pores can be arranged, for example, between several crystals of the usually platelet-shaped tobermorite. However, it is also possible that the pores are contained in a different form in the resulting product, for example in another calcium silicate hydrate phase.

Preferably, the product obtained in the hydrothermal conversion of the raw material mixture is comminuted to a desired target particle size. This is preferably done by breaking and/or grinding. In particular, it is preferred that the comminution takes place in the dry state. This has proven to be particularly simple due to the pores contained in the (intermediate) product. However, it is also possible for one or more of the comminution steps to take place in the moist state, for example as wet grinding. This can be particularly advantageous if dust formation is to be avoided or reduced.

Preferably, the (intermediate) product is ground to a state or particle size in which agglomerates of crystals of tobermorite and/or another calcium silicate hydrate phase are present. For example, if tobermorite has a platelet-shaped crystal structure, each of the agglomerates contains a large number of cavities, which give each agglomerate effective microporosity. This microporosity leads to a particularly large effective surface area, which can be used in a variety of ways. In this regard, optical effects and the property as a catalyst or as a carrier of a catalytically active substance are particularly worth mentioning.

Preferably, a surface modification is carried out in one step of a process variant. Such a surface modification can be, for example, hydrophobization or functionalization, e.g. silanization.

In a preferred variant, the (intermediate) product is dried, broken and then fractionated. This allows it to be adjusted to a desired particle size and/or particle size distribution. If necessary, these steps can be followed by a dedusting step.

In a preferred variant of the process, the (intermediate) product is dry ground and, if necessary, sifted. This is followed by fractionation as required.

If it is advantageous for setting a desired particle size distribution, individual fractions obtained by one or more of the above-mentioned process variants can be mixed with themselves and/or other materials and/or fractions. These are preferably provided dry.

As an alternative or in addition to the above-mentioned process variants, wet grinding and, if necessary, subsequent fractionation can also be carried out. Wet grinding is preferably carried out with materials that have already been pre-crushed.

The products thus obtained can preferably be subjected to wet mixing with themselves and/or with other materials and/or fractions. These are preferably provided as a suspension.

Alternatively or in addition, provision after drying as granules or flour is also conceivable.

The product obtained is preferably packaged for transport and/or further processing. In this regard, the loose provision of the dry or moist product in big bags, sacks, packages, boxes and/or buckets is particularly preferred. Alternatively or additionally, moist products can also be provided as a slurry, for example in a tank, an IBC, bottles, cans, canisters and/or buckets.

Preferably, the method includes a step of adding an additive which imparts to the product or composition a desired physical (and/or mechanical) and/or chemical and/or decorative properties or combinations thereof. For example, such an additive can be deposited on an (inner) surface of the product particles and/or agglomerates in order to impart a particular optical, catalytic and/or mechanical property thereto.

• - Füllstoff für Polymere, insbesondere als wärmedämmender und/oder gewichtsreduzierender Leichtfüllstoff in Polymeren geringer Dichte oder als wärmeleitender und/oder schalldämmender Füllstoff in Polymeren hoher Dichte,
• - Absorber, insbesondere als Absorber eines Inhalts-, Schad-, und/oder Wertstoff aus einem gasförmigen und/oder flüssigen Medium,
• - Dämmstoff für eine Bauanwendung,
• - Grobkorn für die gezielte Verwertung in Kalksandstein,
• - Grobkorn für die gezielte Verwertung in Porenbeton,
• - Grobkorn für die gezielte Verwertung in einer Mineraldämmplatte,
• - Feinanteil für die gezielte Verwertung in Kalksandstein,
• - Feinanteil für die gezielte Verwertung in Porenbeton,
• - Feinanteil für die gezielte Verwertung in einer Mineraldämmplatte,
• - Lärm- und/oder Schallschutz,
• - Leichtfüllstoff für die Hinterfüllung von Polymerformteilen,
• - Porenarmer (vorzugsweise farbiger) Granulatfüllstoff in einem Polymerverbundwerkstoff,
• - Uni- oder gemischtfarbiges Granulat in einem Polymerverbundwerkstoff,
• - Dämmstoff zur Hohlraumbefüllung in einem Mauerstein, insbesondere zum Füllen eines Mauerziegels
• - IR-reflektierender Bestandteil in einer Farbe, einem Putz oder einer anderen Wand- oder Dachbeschichtung,
• - Klimaregulierender Beschichtungs- oder Werkstoff in einem Innenraum, insbesondere zur Wärme- und/oder Feuchteregulierung des Raums

umfasst.A further essential aspect of the present invention is therefore a use of a porous composition as described above, wherein the applications are selected from a group comprising an application as

• - filler for polymers, in particular as a heat-insulating and/or weight-reducing lightweight filler in low-density polymers or as a heat-conducting and/or sound-insulating filler in high-density polymers,
• - Absorber, in particular as an absorber of a content, pollutant and/or valuable substance from a gaseous and/or liquid medium,
• - Insulation material for a building application,
• - Coarse grain for targeted use in sand-lime brick,
• - Coarse grain for targeted use in aerated concrete,
• - Coarse grain for targeted use in a mineral insulation board,
• - Fine fraction for targeted use in sand-lime brick,
• - Fine fraction for targeted use in aerated concrete,
• - Fine fraction for targeted use in a mineral insulation board,
• - Noise and/or sound insulation,
• - Lightweight filler for backfilling polymer moldings,
• - Low-porosity (preferably colored) granular filler in a polymer composite material,
• - Solid or mixed coloured granules in a polymer composite material,
• - Insulating material for filling a cavity in a brick, in particular for filling a brick
• - IR-reflective component in a paint, plaster or other wall or roof coating,
• - Climate-regulating coating or material in an interior space, in particular for regulating the heat and/or humidity of the room

includes.

The preferred embodiments of the composition described above are to be considered as disclosed with regard to the properties of the product obtained by carrying out the method described above. Analogously, the properties of the product obtained by carrying out the method that are only described in terms of the method are also to be considered as disclosed as preferred embodiments of the composition as such.

Likewise, the features disclosed in terms of the process and in relation to the composition should also be deemed to be disclosed for the demonstrated possibilities of using such products or compositions.

Preferred embodiments are also illustrated by the following examples; the disclosure of these examples relates both to the composition as such and to the process and possible applications of the products or compositions obtained.

The substances shown in the following Table 1 were identified as particularly suitable raw materials. In Table 1, the minimum purity of the raw material used (as "main component proportion") is given for each substance. Table 1 also lists the preferred particle sizes of the raw materials used and the preferred maximum tolerable contamination with Fe, Cr, Cu, Ni, Co, Ti and Mn. The information listed in Table 1 on the preferred purity, preferred particle size and maximum tolerable Possible contamination with the metals mentioned should be understood independently. Even if it is preferred that all substances/raw materials have the properties listed in Table 1, it is also possible that not all of the listed substances are used and/or not all of the substances used have all of the listed properties. Table 1: suitable raw materials and their preferred properties Ingredients* Grain size (sieve analysis) Proportion of main ingredient Proportion of the sum of oxides from** Total heavy metals 6* Whiteness, R 457 preferred more preferred most preferred mm Ma-% Ma-% Ma-% Ma-% Ma-% % Quartz sand 0-1.0 >90 <1 <0.5 <0.1 <0.5 >60 gravel 0-6 >90 <1 <0.5 <0.1 <0.5 >60 Crushed sand 0-1.0 >90 <1 <0.5 <0.1 <0.5 >60 White fine lime <0.1 >90 <1 <0.5 <0.1 <0.5 >60 Grey lime <0.1 >90 <1 <0.5 <0.1 <0.5 >60 Cement 11 * <0.1 >90 <1 <0.5 <0.1 <0.5 >60 Quicklime <0.1 >90 <1 <0.5 <0.1 <0.5 >60 Anhydride/Gypsum <0.1 >90 <1 <0.5 <0.1 <0.5 >60 aluminum <0.1 >90 <1 <0.5 <0.1 <0.5 >60 Quartz powder <0.1 >90 <1 <0.5 <0.1 <0.5 >60 Mineral surcharge 10* <0.1 >80 <1 <0.5 <0.1 <0.5 >60 SiO ₂ , amorph <0.1 >90 <1 <0.5 <0.1 <0.5 >60 White cement 11* <0.1 >90 <1 <0.5 <0.1 <0.5 >60 Partially calcined dolomite <0.2 >90 <1 <0.5 <0.1 <0.5 >60 Fully calcined dolomite <0.2 >90 <1 <0.5 <0.1 <0.5 >60 Magnesite, caustic <0.2 >90 <1 <0.5 <0.1 <0.5 >60 Fibers*** <5 >80 <1 <0.5 <0.1 <0.5 >60 Pore-forming agent**** <2 >80 <1 <0.5 <0.1 <0.5 >60 Recvclinq Material***** <5 >80 <1 <0.5 <0.1 <0.5 >60 Pigments 7* Binder 8* Amorphous substances 9* **) Oxide form of the elements Fe, Cr, Cu, Ni, Co, Ti and Mn, ***) polymer-, glass- or mineral-based, synthetic or natural, crystalline or amorphous or based on renewable raw materials, including recycling ****) polymer-, glass- or mineral-based, synthetic or natural, crystalline or amorphous or based on renewable raw materials, including recycling *****) Based on sand-lime brick, aerated concrete, mineral insulation boards from the previous process and the new process described here 6*) Sum of Pb, Ni, Cr, Cu, Hg, As, Sb, Zn 7*) inorganic or organic pigments 8*) inorganic or organic binders, e.g. water glass, phosphate binders, latex, cellulose-based binders, acrylates, styrenes 9*) Glass (broken, round), diatomaceous earth, diatomite, partially calcined kaolin 10*) Silicate (feldspar, calcined kaolin), oxidic, phosphate-based, carbonate-based, sulfate-based 11*) Sum of hydraulically active components

Table 2 lists preferred compositions for specific applications. As can be seen from this table, not all of the listed raw materials have to be included in the composition for every application. Additional processing (e.g. particle size adjustment and/or surface treatment) may be necessary or advantageous for the respective application. Table 2: Preferred compositions by application Application 1. High whiteness granules for roof coating 2. Granules for decorative applications* 3. Powder for use in paints 4. Suspension for use in paints 5. Use as a lightweight filler Components Quartz sand X X gravel Crushed sand X X White fine lime X X X X X Grey lime cement Quicklime Anhydride/Gypsum X X X aluminum X X X Quartz powder (X) (X) X X X Mineral. Surcharge0* New SiO ₂ , amorph X X X White cement Partially calcined dolomite (x) (X) (x) (x) (x) Fully calcined dolomite (x) (X) (X) (X) (X) Magnesite, caustic (X) (X) (X) (X) (X) Fibers*** (X) (X) Porosifying agent**** Recvclinq Material***** (X) (X) (X) (X) (X) Addition of pigments 7* (X) (X) Addition of binding agents 8* (X) (X) Amorphous substances 9* (X) (X) Dry breaking and fractionating, dust removal if necessary 0.5-6mm 0-6mm Dry grind, sift if necessary, and thereby fractionate (X) X Mixing fractions with themselves and/or other mat. Wet grinding and fractionation if necessary X X Wet-mixture with itself and/or with other Mat. Susp. (X) (X) Provision after drying as granules or flour Surface mod., e.g. hydroph. or function. e.g. silanization (X) *) in polymer or cement-based kitchen sinks, worktops, sanitary ware or components

Table 3 shows the results of a test series 1. This was carried out using a sand-lime brick recipe, whereby various materials listed in the table were exchanged with the aim of producing materials that are particularly suitable for the application examples 1, 2 and 3 listed in Table 2. Table 3: Results of test series 1 Ingredients* Proportion in the recipe Grain size Proportion of main ingredient Proportion of the sum of oxides from** Total heavy metals 6* Whiteness, R 457 preferred most preferred Original Ma-% mm Ma-% Ma-% Ma-% Ma-% Ma-% % Quartz sand 45 0-1.0 >90 0.5-1 <0.5 >60 gravel 45 0-6 >90 0.5-1 <0.5 >60 White fine lime 16 <0.1 >90 0.5-1 <0.5 >60 Quartz powder 0 <0.1 >90 -- <0.5 >60 Addition of pigments 7* 0 <0.1 >90 -- -- -- <0.5 >90 V0 Quartz sand 85 0.05-0.3 >90 -- -- 0.05 <0.5 >60 White fine lime 15 <0.1 >90 0.5-1 -- <0.5 >60 V1 White fine lime 20 <0.1 >90 -- -- <0.1 <0.5 >60 Quartz powder 80 <0.1 >90 -- 0.1-0.5 <0.5 >60 V2 White fine lime 25 <0.1 >90 -- -- <0.1 <0.5 >60 Quartz powder 75 <0.1 >90 -- 0.1-0.5 <0.5 >60 V3 White fine lime 20 <0.1 >90 -- - <0.1 <0.5 >60 Quartz powder 80 <0.1 >90 -- 0.1-0.5 <0.5 >60 V4 White fine lime 20 <0.1 >90 -- -- <0.1 <0.5 >60 Quartz powder 80 <0.05 >90 -- 0.1-0.5 <0.5 >60 V5 White fine lime 20 <0.1 >90 -- -- <0.1 <0.5 >60 Quartz powder 79 <0.05 >90 -- 0.1-0.5 <0.5 >60 Addition of TiO ₂ * 1 <0.1 >90 -- -- <0.1 <0.5 >90

Tabelle 4b Bestimmung Steinkennwerte Nr. Bez. Länge [cm] Breite [cm] Höhe [cm] Steinvolumen [cm'] Masse [g] Masse 28 d [g] Rohdichte [g/cm³] Fläche [cm²] Bruchkraft F [kN] Steinfestigkeit nach Autoklavierung [N/mm²] Steinfestigkeit nach28 d [N/mm²] 1 1.1 24,00 11,50 7,30 2014,80 3494,50 1,73 276,00 1241,10 44,97 2 1.2 24,00 11,50 7,30 2014,80 3719,50 1,85 276,00 1858,70 67,34 4 1.4 24,00 11,50 7,30 2014,80 3702,50 3680,10 1,84 276,00 1558,70 - 56,47 7 2.1 24,00 11,50 7,30 2014,80 3359,90 1,67 276,00 1988,70 72,05 8 2.2 24,00 11,50 7,30 2014,80 3507,60 1,74 276,00 2087,20 75,62 10 2.4 24,00 11,50 7,30 2014,80 3673,20 3668,20 1,82 276,00 2259,90 - 81,88 13 3.1 23,90 11,50 7,30 2006,41 3301,00 1,65 274,85 1920,80 69,89 14 3.2 23,90 11,50 7,30 2006,41 3180,10 1,58 274,85 1247,60 45,39 16 3.4 23,90 11,50 7,30 2006,41 3320,40 3301,60 1,65 274,85 1975,80 - 71,89 19 4.1 24,00 11,50 7,30 2014,80 3349,90 1,66 276,00 1013,80 36,73 22 4.4 24,00 11,50 7,30 2014,80 3392,60 1,68 276,00 1150,30 41,68 Table 4a shows the conditions under which various test specimens were produced. The physical properties determined for these test specimens are shown in Table 4b. The abbreviation "QM" in these tables stands for quartz powder. Various types of quartz powder from the applicant, designated "DS 1600" and "DS 16900", were used. The lime used, whose product name is abbreviated to "PC", is ≥ 97% pure CaO with a bulk density of 0.8 kg/dm ³ and a loss on ignition of ≤ 1.5%, as well as a residue in a sieve analysis with a 0.09 mm sieve of ≤ 2%.

Table 4b Determination of stone characteristics No. Ref. Length [cm] Width [cm] Height [cm] Stone volume [cm'] Mass [g] Mass 28 d [g] Bulk density [g/cm ³ ] Area [cm ² ] Breaking force F [kN] Stone strength after autoclaving [N/mm ² ] Stone strength after 28 d [N/mm ² ] 1 1.1 24,00 11,50 7.30 2014.80 3494.50 1.73 276.00 1241.10 44.97 2 1.2 24,00 11,50 7.30 2014.80 3719.50 1.85 276.00 1858.70 67.34 4 1.4 24,00 11,50 7.30 2014.80 3702.50 3680.10 1.84 276.00 1558.70 - 56.47 7 2.1 24,00 11,50 7.30 2014.80 3359.90 1.67 276.00 1988.70 72.05 8th 2.2 24,00 11,50 7.30 2014.80 3507.60 1.74 276.00 2087.20 75.62 10 2.4 24,00 11,50 7.30 2014.80 3673.20 3668.20 1.82 276.00 2259.90 - 81.88 13 3.1 23.90 11,50 7.30 2006,41 3301,00 1.65 274.85 1920.80 69.89 14 3.2 23.90 11,50 7.30 2006,41 3180.10 1.58 274.85 1247.60 45.39 16 3.4 23.90 11,50 7.30 2006,41 3320.40 3301.60 1.65 274.85 1975,80 - 71.89 19 4.1 24,00 11,50 7.30 2014.80 3349.90 1.66 276.00 1013.80 36.73 22 4.4 24,00 11,50 7.30 2014.80 3392.60 1.68 276.00 1150.30 41.68

The above-mentioned specimens were broken, classified into the fractions <0.1 mm, 0.1 - 0.5 mm and 0.5 - 2.5 mm and various tests were carried out on these fractions. The results of these tests are summarized in Table 5 below. For comparison, Table 5 also lists measured values of the initial recipe (referred to as the “original recipe”) and the results for reference materials available on the market for various applications. A product based on kaolin or ceramic, fired at approx. 1100-1300°C, was used as a reference for roof coatings. A product based on highly fired quartz (>1200°C) with >10 Ma-% cristobalite content or light, pigment-coated sand grains was used as a reference for a decorative filler. A product based on flux-calcined diatomite was used as a reference for a filler for applications in paint compositions. All reference products have the disadvantage compared to the compositions described above that they were manufactured using a high energy input, in particular using a high amount of fossil fuels and the associated high CO ₂ emissions. Table 5: Optical values of broken specimens <0.1mm 0.1-0.5mm 0.5-2.5mm Whiteness R457 Yellow value CIE-L CIE a CIE b CIE-L CIE a CIE b CIE-L CIE a CIE b Original recipe 44.18 32.00 80.05 3.73 13.96 74.16 3.46 11.09 70.31 3.04 9.35 V0: Quartz = Fine quartz 64.33 14.55 87.72 1.93 6.49 81.39 2.16 6.24 76.33 2.37 5.76 D1 V1: Quartz powder + pure CaO, 1 81.28 5.17 93.49 0.65 2.41 88.78 1.03 3.38 88.56 1.29 3.74 D2 V2: Quartz powder + pure CaO, 2 81.03 5.09 93.58 0.62 2.38 88.63 1.19 3.55 85.91 1.32 3.75 D3 V3: Quartz powder + pure CaO, 3 81.41 4.85 93.57 0.64 2.24 89.14 1.02 3.16 85.75 1.32 3.48 D4 V4: Quartz powder + pure CaO, 4 82.97 4.83 94.26 0.62 2.26 88.84 1.13 3.52 85.77 1.31 3.65 D4+ _TiO2 V5: Quartz powder + pure CaO, 4 + TiO ₂ additive, 5 84.12 4.12 95.87 0.59 2.02 90.91 0.98 3.01 91.23 0.99 2.85 1. Reference roof coating 91.41 -0.17 6.46 2. Reference Decorative Filler 87.67 -0.01 1.37 3. Reference Color Filler 84.0 5.02 96.67 0.62 2.53

As can be seen from Table 5, the results demonstrate, on the one hand, that targeted improvements in the end products can be achieved through a specifically selected characteristic of the input materials and, on the other hand, that materials can be produced that achieve or even exceed the target characteristics of products available on the market, expressed here among other things by the optical values.

Table 6 shows the water absorption according to DIN EN 14411 for the samples of test series 1 described above. This test series was carried out on the basis of a sand-lime brick recipe as described above. The water absorption according to DIN EN 14411 is low for the basic recipe (also known as the original recipe) at 6 mass% (Ma%). This suggests that there are no or only small pores. The water absorption Eb is classified according to DIN EN 14411. It describes the proportion of water that can be absorbed by the ceramic material, based on the respective mass in %.

As can be seen from Table 6, an increased water absorption (“WA”) according to DIN EN 14411 can be measured for all samples (V0 - V4) that were modified compared to the basic recipe in test series 1. Compared to recipe V0, the porosity and thus the water absorption of the Samples V1 - V4 were significantly increased again. For the analyses on which the values shown in Table 6 are based, samples of the fraction with a particle size (sieve analysis) in the range of 0.5 - 2.5 mm were used. Table 6: Water absorption according to DIN EN 14411 WA*, Ma-% Original recipe 6 V0: Quartz = Fine quartz 16 V1: Quartz powder + pure CaO, 1 20 V2: Quartz powder + pure CaO, 2 20 V3: Quartz powder + pure CaO, 3 21 V4: Quartz powder + pure CaO, 4 22 *Water absorption according to DIN EN 14411

The compositions described above therefore offer a new opportunity to provide alternative materials for these products that can be produced inexpensively with a low proportion of fossil fuels. The compositions can usually be produced using existing plant technology and thus with very little investment.

The applicant reserves the right to claim all features disclosed in the application documents as essential to the invention, provided that they are new compared to the prior art, either individually or in combination.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• EP 3235794 B1 [0014]

Claims (10)

Hydrothermally produced composition comprising tobermorite and/or another calcium silicate hydrate phase, characterized in that the composition has a plurality of pores and comprises at least one substance which is/are selected from a group comprising quartz sand, gravel, crushed sand, fine white lime, grey lime, cement, quicklime, anhydride/gypsum, aluminium and quartz powder, each of these substances having a purity which is ≥ 90%. Composition according to Claim 1 , characterized in that it has a whiteness R457 ≥ 70, preferably ≥ 75, more preferably ≥ 78, further preferably ≥ 80, most preferably ≥ 81. Composition according to one of the preceding claims, characterized in that the proportion of the elements Fe, Cr, Cu, Ni, Co, Ti and Mn measured as their oxide form in the composition is ≤ 1 mass percent, preferably ≤ 0.75 mass percent, more preferably ≤ 0.5 mass percent, further preferably ≤ 0.25 mass percent, most preferably ≤ 0.1 mass percent. Composition according to one of the preceding claims, characterized in that it comprises at least one substance which is selected from a group comprising amorphous SiO ₂ , white cement, partially calcined dolomite, fully calcined dolomite, magnesite (preferably caustic), fibers, porosity agents, recycled material preferably based on sand-lime brick, aerated concrete or mineral insulation boards, pigments, binders, preferably inorganic or organic binders, particularly preferably water glass, phosphate binders, latex, cellulose-based binders, acrylate or styrene and amorphous substances, preferably glass (broken or round), diatomaceous earth, diatomite or partially calcined kaolin. Composition according to one of the preceding claims, characterized in that the substance and/or the substances which is/are selected from a group comprising quartz sand, gravel, crushed sand, fine white lime, grey lime, cement, quicklime, anhydride/gypsum, aluminium and quartz powder, wherein preferably each of these substances has a purity, is used in a purity of ≥ 92%, preferably ≥ 95%. Composition according to one of the preceding claims, characterized in that it is in particulate form, the average particle size (sieve analysis) being ≤ 80 mm, preferably ≤ 50 mm, further preferably ≤ 25 mm, more preferably ≤ 10 mm, particularly preferably ≤ 5 mm. Process for producing a porous composition, preferably according to one of the preceding claims, characterized by the steps: - providing a first raw material or several first raw materials with a purity ≥ 90%, wherein the raw material/raw materials is/are selected from a group comprising quartz sand, gravel, crushed sand, fine white lime, grey lime, cement, quicklime, anhydride/gypsum, aluminium and quartz powder, - mixing the raw materials, - hydrothermal conversion of the raw material mixture to the composition by exposure to steam. Procedure according to Claim 7 , characterized in that at least one second raw material, preferably several second raw materials are used to produce the raw material mixture, wherein the at least one second raw material is selected from a group comprising amorphous SiO ₂ , white cement, partially calcined dolomite, fully calcined dolomite, magnesite (preferably caustic), fibers, porosity agents, recycled material preferably based on sand-lime brick, aerated concrete or mineral insulation boards, pigments, binders, preferably inorganic or organic binders, particularly preferably water glass, phosphate binders, latex, cellulose-based binders, acrylate or styrene and amorphous substances, preferably glass (broken or round), diatomaceous earth, diatomite or partially calcined kaolin. Procedure according to Claim 7 or 8th , characterized in that the proportion of the elements Fe, Cr, Cu, Ni, Co, Ti and Mn measured as their oxide form in the at least one first and/or the at least one second raw material, preferably in each of the raw materials used, is ≤ 1 mass percent, preferably ≤ 0.75 mass percent, more preferably ≤ 0.5 mass percent, further preferably ≤ 0.25 mass percent, most preferably ≤ 0.1 mass percent. Use of a composition according to any of the Claims 1 - 7 , selected from a group that includes applications as - Filler for polymers, in particular as a heat-insulating and/or weight-reducing lightweight filler in low-density polymers or as a heat-conducting and/or sound-insulating filler in high-density polymers, - Absorber, in particular as an absorber of a constituent, pollutant and/or valuable substance from a gaseous and/or liquid medium, - Insulating material for a building application, - Coarse grain for targeted use in sand-lime brick, - Coarse grain for targeted use in aerated concrete, - Coarse grain for targeted use in a mineral insulation board, - Fine fraction for targeted use in sand-lime brick, - Fine fraction for targeted use in aerated concrete, - Fine fraction for targeted use in a mineral insulation board, - Noise and/or sound insulation, - Lightweight filler for backfilling polymer moldings, - Low-porosity (preferably colored) granulate filler in a polymer composite material, - Single- or mixed-colored granulate in a polymer composite material, - insulating material for filling a cavity in a masonry unit, in particular for filling a building brick, - IR-reflecting component in a paint, plaster or other wall or roof coating, - climate-regulating coating or material in an interior space, in particular for regulating the heat and/or humidity of the room.