Reducing the viscosity of an aluminum sulfate suspension using an alkali metal compound

Abstract

The present invention relates to the use of at least one soluble alkali metal compound for the adjustment, in particular for the reduction, of the viscosity of an aluminum sulfate suspension, wherein the alkali metal is selected from the group consisting of sodium, potassium and / or lithium.

Description

Technical Field

[0001] This invention relates to formulations for adjusting, and more particularly for reducing, the viscosity of aluminum sulfate suspensions. The invention also relates to an aluminum sulfate suspension. Existing technology

[0002] Many substances are known to promote the curing and hardening of mineral binder compositions. Known examples include strongly alkaline reactive substances such as alkali metal hydroxides, alkali metal carbonates, alkali metal silicates, alkali metal aluminates, and alkaline earth metal chlorides.

[0003] However, alkali-free accelerators are primarily used, among which aluminum sulfate-based suspension accelerators have been prepared as particularly effective and offer good cost-effectiveness. However, a problem with these accelerators is that their viscosity increases significantly with increasing active ingredient content. This particularly complicates production, the precise metering of the accelerator, and the miscibility with the mineral binder composition to be accelerated.

[0004] WO 2005 / 075381 A1 describes, for example, coagulation and hardening accelerators comprising aluminum hydroxide, aluminum sulfate and organic acids, wherein the accelerator has a molar ratio of aluminum to organic acid of less than 0.65.

[0005] EP 0 812 812 B1 discloses an alkali-free accelerator dispersion based on aluminum sulfate and alkanolamine in the absence of aluminum hydroxide.

[0006] However, a major drawback of large quantities of acids and alkanolamines is their leaching potential, which can cause environmental pollution. They are also disadvantageous due to their cost.

[0007] EP 1 878 713 A1 (Construction Research and Technology GmbH) describes an accelerator for shotcrete or shotcrete in the form of an aqueous dispersion containing 25% to 40% by weight of aluminum sulfate and aluminum hydroxide, wherein the molar ratio of aluminum to sulfate in the dispersion is 1.35 to 0.70. The aqueous dispersion also contains an inorganic stabilizer comprising magnesium silicate in the form of sepiolite. If sepiolite is used at a proportion of 0.2-3% by weight, according to EP 1 878 713 A1, the result is not only stabilization of the dispersion over a wide range of desired amounts of aluminum and sulfate, but also a favorable viscosity for the shotcrete accelerator.

[0008] However, a drawback of such accelerators is that achieving high levels of active substances requires the addition of additional aluminum hydroxide and an increase in the aluminum-to-sulfate ratio, which is undesirable in some cases. This results in a relatively high cost for the accelerator, as aluminum hydroxide is expensive. Furthermore, although magnesium silicate used as a stabilizer in the form of sepiolite is an excellent stabilizer for shotcrete accelerators, sepiolite has been found to be ineffective in reducing viscosity. Conversely, adding sepiolite immediately after production always leads to an increase in the viscosity of the aluminum sulfate suspension.

[0009] Therefore, although aluminum sulfate suspensions can be stable at relatively high active substance contents, it is impossible to actively influence or intentionally adjust the viscosity of such aluminum sulfate suspensions, especially the viscosity immediately after production.

[0010] The applicant’s unpublished patent application EP 19207659.4 shows that, in some cases, the viscosity of aluminum sulfate suspension can be reduced by adding magnesium compounds.

[0011] However, solutions with improved efficacy and cheaper options are still needed to reduce viscosity.

[0012] Therefore, new and improved solutions are still needed to overcome the above-mentioned shortcomings as much as possible. Invention Overview

[0014] The object of this invention is to provide a solution capable of producing an aluminum sulfate suspension with the highest possible aluminum sulfate content and the lowest possible viscosity. More specifically, the low viscosity is achieved immediately after the addition of the soluble alkali metal compound to the aluminum sulfate suspension, and preferably remains low even at a later point in time after the addition of the soluble alkali metal compound. This is achieved particularly without affecting the ratio of aluminum to sulfate and preferably without impairing the effectiveness of the other components of the aluminum sulfate suspension. The aluminum sulfate suspension should be particularly suitable as a very effective curing accelerator and / or hardening accelerator for compositions containing mineral binders, especially for shotcrete or shotcrete mortar, wherein the aluminum sulfate suspension is particularly suitable as a shotcrete accelerator. Furthermore, the solution can be prepared in the most inexpensive and simple manner possible.

[0015] It has been surprisingly discovered that the object of the invention can be achieved through the use claimed in claim 1.

[0016] Therefore, at least one soluble alkali metal compound is used to adjust, and more particularly to reduce, the viscosity of aluminum sulfate suspensions, wherein the alkali metal is selected from sodium, potassium and / or lithium.

[0017] As already demonstrated, for the same aluminum sulfate content, the use of soluble alkali metal compounds can significantly reduce the viscosity of aluminum sulfate suspensions, and / or significantly increase the aluminum sulfate content for the same viscosity. Therefore, relatively inexpensive aluminum sulfate suspensions with high aluminum sulfate content and relatively low viscosity can be produced in a simple manner, making them particularly suitable as curing and hardening accelerators for shotcrete and shotcrete mortar.

[0018] The use of at least one soluble alkali metal compound is particularly effective in reducing the viscosity of aluminum sulfate suspension within 1-48 hours, preferably 1-24 hours or 1-12 hours, and more particularly 2-6 hours, after it has been added to the aluminum sulfate suspension or after all the components used to produce the aluminum sulfate suspension have been mixed together. A particular advantage is that the viscosity peaks that may occur in the first few hours after the preparation of the aluminum sulfate suspension are reduced, which is beneficial for economical production.

[0019] Furthermore, soluble alkali metal compounds have been shown to be effective as agents for adjusting, and more particularly reducing and / or maintaining, viscosity, even at later time points, especially 1–3 months after addition to aluminum sulfate suspensions. This is particularly true in aluminum sulfate suspensions with an aluminum sulfate (Al2(SO4)3) content >34% by weight.

[0020] Because of the use of soluble alkali metal compounds, alterations to the aluminum-sulfate ratio can be avoided with proper selection. However, the use of alkali metal aluminates can also increase the Al content in the suspension, but this is generally not always advantageous.

[0021] Alkali metal compounds of Na, K, and Li exhibit better efficacy than magnesium compounds. Furthermore, Na and K compounds are cheaper than other chemicals, thus achieving an excellent cost-performance ratio. Problems caused by precipitation at high concentrations, which can occur when using magnesium compounds (such as magnesium sulfate precipitates), are avoided.

[0022] Soluble alkali metal compounds can also be directly combined with conventional and stable magnesium silicate, especially sepiolite, without adversely affecting the efficacy of the soluble alkali metal compounds. For example, in aluminum sulfate suspensions, magnesium silicate, especially sepiolite, can be used in combination with soluble alkali metal compounds if desired, thereby obtaining a particularly stable aluminum sulfate suspension with high active substance content and low viscosity.

[0023] Furthermore, if necessary, potentially problematic and / or expensive substances, such as alkanolamines, carboxylic acids, and aluminum hydroxide, can be omitted. This can be done without significant loss of promoting effect.

[0024] Other aspects of the invention are the subject of the other independent claims. Particularly preferred embodiments of the invention are the subject of the dependent claims. Invention Details

[0026] In a first aspect, the present invention relates to the use of at least one soluble alkali metal compound for adjusting, and more particularly for reducing, the viscosity of aluminum sulfate suspensions, wherein the alkali metal is selected from sodium, potassium, and / or lithium. Mixtures of two or more soluble alkali metal compounds may be used, but for practical reasons, the use of a single alkali metal compound is generally preferred.

[0027] Aluminum sulfate suspension is a heterogeneous mixture of a liquid (more particularly water) and finely dispersed aluminum sulfate particles therein. Aqueous aluminum sulfate suspensions are particularly preferred. In addition to particulate aluminum sulfate, some aluminum sulfate may also be in dissolved and / or chemically modified forms, especially in aqueous aluminum sulfate suspensions. An example of a chemically modified form of aluminum sulfate is feldspar (AlOHSO4·5H2O). Aluminum sulfate suspensions are not pure solutions as described herein; rather, finely dispersed aluminum sulfate particles are always present in the liquid phase, especially in water. Besides the liquid and aluminum sulfate, aluminum sulfate suspensions may also contain other components in dissolved and / or solid forms.

[0028] Aluminum sulfate suspensions are particularly preferred as curing and / or hardening accelerators for mineral binders, especially as shotcrete accelerators. Accordingly, soluble alkali metal compounds are preferably used to adjust the viscosity of the aluminum sulfate suspension-based curing and / or hardening accelerators used in compositions containing mineral binders, especially cement, wherein the aluminum sulfate suspension is preferably a shotcrete accelerator, particularly for shotcrete or shotcrete mortar.

[0029] The term "curing and / or hardening accelerator" specifically refers to a substance that, when added to a mineral binder and compared to a blank sample without the substance / accelerator, results in an increase in the compressive strength of the mineral binder after a defined time following mixing, particularly within 2 minutes to 24 hours after mixing.

[0030] In the context of this invention, "soluble alkali metal compound" is an alkali metal compound that is soluble in distilled water adjusted to pH 2 with HCl at 25°C and 1 bar at a pressure of 1 bar, to a degree of at least 5 g / L.

[0031] Specifically, "adjusting viscosity" in this document refers to controlling and / or adjusting the viscosity of an aluminum sulfate suspension by means of a soluble alkali metal compound. More specifically, the presence of a soluble alkali metal compound alters or reduces the viscosity of an aluminum sulfate suspension compared to one that does not contain a soluble alkali metal compound but is otherwise identical in composition.

[0032] Viscosity was specifically determined according to standard DIN EN ISO 2431:2011. This was preferably carried out using an ISO No. 6 or No. 4 cup at a temperature of 23°C.

[0033] Unless otherwise stated, the weight and molar ratios in each case are based on the viscosity-adjusted ready-to-use aluminum sulfate suspension. The ready-to-use aluminum sulfate suspension is specifically designed for direct use as a curing and / or hardening accelerator. Therefore, in addition to aluminum sulfate and the liquid, the ready-to-use aluminum sulfate suspension includes at least one soluble alkali metal compound and optionally other components.

[0034] Aluminum sulfate suspensions are preferably chloride-free. Even when using alkali metal compounds, aluminum sulfate suspensions are preferably alkali-free or have a low alkali content.

[0035] In building chemistry, "alkali-free" generally means that, based on the total weight of the composition or aluminum sulfate suspension and in sodium oxide equivalents (Na₂O), the composition contains less than 1% by weight of alkali metal ions and / or alkaline earth metal ions. Here, "low alkali content" means that, based on the total weight of the composition or aluminum sulfate suspension and in sodium oxide equivalents (Na₂O), the composition contains no more than 5% by weight of alkali metal ions and / or alkaline earth metal ions.

[0036] "Na2O equivalent" refers to the weight obtained if all alkali metal ions (especially Na and K) were present as Na2O.

[0037] In building chemistry, "chlorine-free" usually means that the composition has less than 0.1% chloride ions, based on the total weight of the composition or aluminum sulfate suspension.

[0038] Soluble alkali metal compounds are particularly used to adjust viscosity, and especially to reduce viscosity.

[0039] Specifically, soluble alkali metal compounds are used to adjust the viscosity of aluminum sulfate suspensions, particularly to reduce the viscosity of the aluminum sulfate suspensions. This viscosity adjustment, especially the reduction, is preferably completed within a time period of 1-168 hours, more preferably 1-48 hours, and particularly 1-24 hours after obtaining an aluminum sulfate suspension with the added soluble alkali metal compound. In particular, the soluble alkali metal compound can reduce the viscosity of the aluminum sulfate suspension within a time period of 1-6 hours after its addition to the suspension or after all components used to produce the aluminum sulfate suspension have been mixed, which is particularly advantageous for production.

[0040] In particular, the viscosity, which has been adjusted in one step, remains stable over an extended period of time, more specifically over several months. Therefore, soluble alkali metal compounds are particularly useful for adjusting, and especially for reducing, the viscosity of aluminum sulfate suspensions over several months, very particularly preferably over 1-3 months after the addition of the soluble alkali metal compound. This is especially true for aluminum sulfate suspensions having a proportion of >34% by weight of aluminum sulfate (Al2(SO4)3).

[0041] Because soluble alkali metal compounds can adjust the viscosity, particularly reduce it, of an aluminum sulfate suspension containing them within a period of 1-168 hours, preferably 1-48 hours, and especially 6-24 hours after preparation, the viscosity of the aluminum sulfate suspension can be adjusted to the desired value even shortly after preparation. This allows for shorter production times, as the aluminum sulfate suspension can be used as intended within hours of preparation, particularly as a curing and / or hardening accelerator.

[0042] Because soluble alkali metal compounds can further adjust and reduce the viscosity of aluminum sulfate suspensions, particularly over extended periods of several months, after the addition of soluble alkali metal compounds, long-term viscosity reduction can be achieved. Therefore, if desired, aluminum sulfate suspensions can be stored at a substantially constant viscosity for an extended period.

[0043] Therefore, soluble alkali metal compounds can be used in methods for adjusting the viscosity of aluminum sulfate suspensions. Thus, another aspect of the invention is a method for adjusting the viscosity of an aluminum sulfate suspension, particularly reducing its viscosity, preferably within a time period of 1-168 hours, preferably 1-48 hours, especially 6-24 hours after obtaining an aluminum sulfate suspension with the addition of a soluble alkali metal compound, and / or for adjusting the viscosity, more particularly reducing its viscosity, over a longer time period, more particularly over a period of several months, said method comprising the following steps:

[0044] a) Aqueous preparations of pre-contained aluminum sulfate, and

[0045] b) Incorporation of at least one soluble alkali metal compound

[0046] c) Optional mixing with other aluminum sulfates

[0047] An aluminum sulfate suspension was obtained from this process.

[0048] or

[0049] a) Aqueous preparations pre-containing soluble alkali metal compounds, and

[0050] b) Mix in aluminum sulfate to obtain an aluminum sulfate suspension.

[0051] All variations are possible. In some cases, alternating the addition of components is a preferred approach. The formulations described herein are solutions or suspensions. Therefore, aqueous formulations are solutions or suspensions in water.

[0052] Aqueous aluminum sulfate preparations are solutions or suspensions of aluminum sulfate in water. Aqueous preparations may also contain a certain proportion of dissolved aluminum sulfate and a certain proportion of suspended aluminum sulfate.

[0053] The curing and / or hardening accelerator of the present invention for use in compositions containing hydraulic binders, particularly for shotcrete or shotcrete, is an aluminum sulfate suspension.

[0054] Soluble alkali metal compounds can be added directly to the aluminum sulfate preparation during the production process. Alternatively, they can be added shortly after production, such as within one hour. Finally, they can be added a considerable time after production, such as five days or more.

[0055] The soluble alkali metal compound is preferably an alkaline alkali metal compound. This means that when a soluble alkali metal compound is added to acidified water, it can increase the pH value of distilled water that has been adjusted to pH=2 with HCl at 25°C and 1 bar pressure.

[0056] Soluble alkali metal compounds preferably comprise alkali metal salts and / or alkali metal complexes.

[0057] The soluble alkali metal compounds used in this invention allow for the formulation of highly efficient curing and / or hardening accelerators that are substantially calcium-free. Since calcium can sometimes slow the reaction or dissolution of cement clinker, substantially calcium-free curing and / or hardening accelerators may be advantageous.

[0058] The alkali metal in the alkali metal compound is selected from sodium, potassium, and / or lithium, preferably sodium and / or potassium. In particular, the soluble alkali metal compound is an aluminate, oxide, hydroxide, carbonate, bicarbonate, nitrate, sulfate, phosphate, halide, formate, acetate, citrate, thiocyanate, silicate, or a mixture thereof.

[0059] More preferably, the soluble alkali metal compound is an aluminate, oxide, hydroxide, carbonate, bicarbonate, nitrate, formate, acetate, citrate, or a mixture thereof.

[0060] Preferably, the soluble alkali metal compound is sodium aluminate, sodium carbonate, sodium bicarbonate, sodium oxide, sodium hydroxide, potassium aluminate, potassium carbonate, potassium bicarbonate, potassium oxide, potassium hydroxide, lithium aluminate, lithium carbonate, lithium bicarbonate, lithium oxide, lithium hydroxide, or mixtures thereof, with sodium or potassium compounds being preferred. Very particularly preferred, the alkali metal compound is selected from sodium aluminate, sodium carbonate, sodium bicarbonate, sodium oxide, sodium hydroxide, potassium aluminate, or mixtures thereof.

[0061] These alkali metal compounds have been found to be particularly advantageous in this study because they can achieve a significant reduction in viscosity without adversely affecting other components. Furthermore, these substances exhibit good usability.

[0062] However, other soluble alkali metal compounds can also be used in principle.

[0063] At least one soluble alkali metal compound, particularly the aforementioned soluble alkali metal compound, may be added, for example, in powder form or in aqueous solution form to the aluminum sulfate suspension or during the production process of the aluminum sulfate suspension. Sodium aluminate may be added, for example, in powder form or in aqueous solution form.

[0064] The amount of soluble alkali metal compound is preferably selected such that, based on the total weight of the aluminum sulfate suspension, the proportion of alkali metal atoms is 0.02-5% by weight, more particularly 0.05-2% by weight, especially preferably 0.1-1.4% by weight, and especially 0.2-0.7% by weight.

[0065] These amounts are particularly effective at reducing viscosity without significantly adversely affecting the curing and / or hardening accelerator properties of aluminum sulfate suspensions.

[0066] Based on the total weight of the aluminum sulfate suspension, the aluminum sulfate suspension preferably has 19-40% by weight, more particularly 24-36% by weight, and especially 28-34% by weight of sulfate (SO4). - )Proportion.

[0067] More preferably, based on the total weight of the aluminum sulfate suspension, the aluminum sulfate suspension has an aluminum (Al) content of 3.5-10% by weight, more particularly 4.5-8.7% by weight, and especially 5.4-7% by weight.

[0068] Using this ratio of aluminum and sulfate, an aluminum sulfate suspension with a high content of active substances can be prepared, which exhibits particularly good curing and / or hardening promoting effects.

[0069] The aluminum sulfate suspension advantageously comprises aluminum sulfate, basic aluminum sulfate, sulfuric acid, aluminum hydroxide, and / or basic aluminum carbonate. Aluminum sulfate is particularly preferred.

[0070] The sulfates in the aluminum sulfate suspension are particularly derived from aluminum sulfate, basic aluminum sulfate, and / or sulfuric acid. Aluminum sulfate is especially preferred. In other words, the accelerator particularly contains at least one of the substances mentioned as a sulfate source.

[0071] The aluminum in the accelerator is advantageously derived from aluminum sulfate, basic aluminum sulfate, aluminum hydroxide, and / or basic aluminum carbonate. Aluminum sulfate is particularly preferred. In other words, the accelerator more particularly contains at least one of the substances mentioned as an aluminum source.

[0072] In an advantageous embodiment, the aluminum sulfate suspension contains 22-46% by weight, more particularly 28-43% by weight, and preferably 34-41% by weight of aluminum sulfate (Al2(SO4)3), based on the total weight of the aluminum sulfate suspension.

[0073] The aluminum sulfate that can be prepared may contain varying amounts of water of crystallization. The aluminum sulfate commonly used is aluminum sulfate tetradecahydrate (Al2(SO4)3·approximately 14H2O). It is also commonly referred to as 17% aluminum sulfate because it contains approximately 17% Al2O3.

[0074] Unless otherwise stated, the amounts of aluminum sulfate mentioned in this document are based on anhydrous Al2(SO4)3 in each case. The amounts of various reference compounds can be readily calculated with reference to the following relationship: Al2(SO4)3·about 14H2O contains 57% by weight of Al2(SO4)3 or 17% by weight of Al2O3.

[0075] Aluminum sulfate can also be prepared by reacting aluminum hydroxide and / or aluminum metal with sulfuric acid during the preparation of an aluminum sulfate suspension, wherein sulfate ions are formed accordingly in an aqueous solution. Typically, aluminum sulfate can be prepared by reacting basic aluminum compounds and / or aluminum metal with sulfuric acid.

[0076] In another advantageous embodiment, the aluminum sulfate suspension contains 0.01-15% by weight, more particularly 0.05-5% by weight, and especially preferably 0.1-2% by weight of aluminum hydroxide, based on the total weight of the aluminum sulfate suspension.

[0077] Therefore, for example, the aluminum content can be increased in an effective manner independent of the sulfate content of the aluminum sulfate suspension.

[0078] Aluminum hydroxide can be used in amorphous and / or crystalline forms. Amorphous aluminum hydroxide is advantageously used. This is especially true because crystalline aluminum hydroxide typically reacts fully only at temperatures >130°C and pressures >1 bar. Aluminum hydroxide can also be used in basic aluminum carbonate, basic aluminum sulfate, or similar forms.

[0079] In an advantageous embodiment, the molar ratio of aluminum to sulfate in the aluminum sulfate suspension is less than or equal to 0.9, preferably less than or equal to 0.85, more preferably less than or equal to 0.8, even more preferably less than or equal to 0.74, very particularly preferably less than or equal to 0.7, especially 2:3. In this case, the aluminum sulfate suspension can be prepared in a particularly simple manner by suspending aluminum sulfate (Al2(SO4)3). When a soluble alkali metal compound is used according to the invention, an aluminum sulfate suspension with high active substance content and low viscosity can therefore be prepared.

[0080] In another advantageous embodiment, the molar ratio of aluminum to sulfate in the aluminum sulfate suspension is 0.5-2, preferably 0.67-1.35, and particularly 0.7-1.0. This aluminum sulfate suspension has improved efficacy for certain applications.

[0081] Based on the total weight of the aluminum sulfate suspension, the aluminum sulfate suspension preferably has a water content of 30-80% by weight, more particularly 40-70% by weight, and preferably 50-65% by weight. The water of crystallization in the components of the aluminum sulfate suspension, such as the water of crystallization from aluminum sulfate, is included in the calculations herein.

[0082] In another preferred embodiment, the soluble alkali metal compound for reducing viscosity is used in combination with a magnesium compound, a calcium compound, and / or an iron compound. Specifically, both calcium and iron compounds are used. Without being bound by any particular theory, it is believed that the calcium and iron compounds further enhance the effect of the soluble alkali metal compound. In a particularly preferred embodiment, the soluble alkali metal compound for reducing the viscosity of the aluminum sulfate suspension is used in combination with a magnesium compound.

[0083] Magnesium compounds, calcium compounds and / or iron compounds, especially oxides, hydroxides, carbonates, nitrates, sulfates, phosphates, halides, formates, acetates and / or citrates.

[0084] Magnesium compounds, calcium compounds and / or iron compounds are preferably oxides, hydroxides, carbonates, nitrates, formates, acetates and / or citrates.

[0085] Calcium compounds are particularly preferred as calcium carbonate, calcium oxide, and / or calcium hydroxide. Calcium oxide is particularly preferred. Magnesium compounds are particularly preferred as magnesium carbonate, magnesium oxide, and / or magnesium hydroxide.

[0086] Calcium compounds, especially Ca(OH)₂, CaCO₃, and / or CaO. CaO is particularly preferred. Magnesium compounds, especially Mg(OH)₂, MgCO₃, and / or MgO. MgO is particularly preferred.

[0087] The amount of calcium or magnesium compound is specifically selected such that, based on the total weight of the aluminum sulfate suspension, the proportion of calcium or magnesium atoms is 0.001-4 wt%, preferably 0.01-2 wt%, more particularly 0.07-1.4 wt%, especially 0.1-0.7 wt%.

[0088] If CaO is used as the calcium compound, the proportion of CaO is advantageously 0.001-5 wt%, preferably 0.01-3 wt%, more particularly 0.1-2 wt%, and especially 0.2-1 wt%, based on the total weight of the aluminum sulfate suspension. If MgO is used as the magnesium compound, the proportion of MgO is advantageously 0.001-5 wt%, preferably 0.01-3 wt%, more particularly 0.1-2 wt%, and especially 0.2-1 wt%, based on the total weight of the aluminum sulfate suspension.

[0089] Iron compounds, especially iron oxides, are preferred. Iron compounds, particularly Fe₂O₃, are particularly preferred.

[0090] The amount of iron compound is specifically selected such that, based on the total weight of the aluminum sulfate suspension, the proportion of iron atoms is 0.001-10% by weight, more particularly 0.1-5% by weight, especially 0.2-2% by weight, and very particularly preferably 0.1-0.6% by weight.

[0091] If Fe2O3 is used as the iron compound, the proportion of Fe2O3 is advantageously 0.001-14.3% by weight, more particularly 0.1-7.1% by weight, and especially 0.2-2% by weight, based on the total weight of the aluminum sulfate suspension.

[0092] In another advantageous embodiment, the aluminum sulfate suspension contains silica.

[0093] The term "silicon dioxide" as used herein refers not only to orthosilicic acid but also to all forms of silicon dioxide, including orthosilicic acid anhydrides, actual silicon dioxide, and colloidal, precipitated, or pyrolytic silicon dioxide or silicon powder. Silicon dioxide is preferably silicon oxide or SiO2.

[0094] Silica is preferably present in an amount such that the silica content, based on the total weight of the aluminum sulfate suspension, is from 0.001% to 5% by weight, preferably from 0.1% to 2% by weight, and even more preferably from 0.2% to 1% by weight.

[0095] In addition, to prepare the aluminum sulfate suspension, at least one other divalent or higher valence metal salt, more particularly a metal sulfate, may be used, preferably in an amount of 0.1-5% by weight based on the total weight of the aluminum sulfate suspension. A particularly preferred other metal sulfate is manganese(II) sulfate. Ferric sulfate is also suitable.

[0096] It may be further advantageous when the aluminum sulfate suspension additionally contains 0.1-15% by weight, preferably 0.1-5% by weight, and particularly 0.2-2% by weight of an alkanolamine based on the total weight of the aluminum sulfate suspension. The alkanolamine used is advantageously monoethanolamine, diethanolamine, triethanolamine, and / or methyldiisopropanolamine.

[0097] The aluminum sulfate suspension may additionally contain stabilizers such as bentonite, palygorskite (e.g., Actigel 208), kaolin, and / or magnesium silicate, such as sepiolite. Preferably, the aluminum sulfate suspension of the present invention is free of organic plasticizers, particularly polycarboxylates, polycarboxylate esters, and / or polycarboxylate ethers.

[0098] Aluminum sulfate suspensions may contain magnesium silicate, particularly flake silicates and / or foliates, such as sepiolite and / or bentonite. If present, the proportion of magnesium silicate is advantageously 0.001-5% by weight, preferably 0.1-2% by weight, especially 0.2-1% by weight, based on the total weight of the aluminum sulfate suspension. Magnesium silicate is inert herein or insoluble according to the solubility definition above, and contributes to phase stability.

[0099] Furthermore, soluble alkali metal compounds can be used in combination with magnesium silicate to adjust, more particularly reduce, viscosity and simultaneously stabilize the aluminum sulfate suspension. Magnesium silicate is especially flake silicates and / or foli silicates, such as sepiolite and / or bentonite. Sepiolite is particularly preferred. Magnesium silicate, especially sepiolite, is preferably used at a ratio of 0.001-5% by weight, more preferably 0.1-2% by weight, particularly 0.2-1% by weight, based on the total weight of the aluminum sulfate suspension. The amount of the soluble alkali metal compound is preferably selected such that the proportion of alkali metal atoms based on the total weight of the aluminum sulfate suspension is 0.02-5% by weight, more particularly 0.05-2% by weight, particularly preferably 0.1-1.4% by weight, particularly 0.2-0.7% by weight.

[0100] Aluminum sulfate suspensions may, of course, contain other components. These components may in particular be fluorine compounds, such as hydrofluoric acid, alkali metal fluorides, and / or fluorine complexes. They can, for example, further enhance the promoting effect.

[0101] Specifically, based on the total weight of the aluminum sulfate suspension, the aluminum sulfate suspension contains 0.01-10% by weight, more particularly 0.05-2% by weight, and preferably 0.1-0.5% by weight of fluoride. This can enhance the promoting effect of the aluminum sulfate suspension in some cases.

[0102] The aforementioned substances are more specifically present in solution at least partially as ions. However, they can also exist, for example, in complexed or undissolved forms in aluminum sulfate suspensions.

[0103] Particularly advantageous aluminum sulfate suspensions contain or consist of, for example, the following components (in weight percent, based on the total weight of the aluminum sulfate suspension in each case):

[0104] a) 19% to 40% by weight, more particularly 24% to 36% by weight, especially 28% to 34% by weight of sulfate;

[0105] b) 3.5-10% by weight, more particularly 4.5-8.7% by weight, especially 5.4-7% by weight of aluminum;

[0106] c) at least one soluble alkali metal compound, wherein the alkali metal is selected from sodium, potassium and / or lithium, and the amount is such that, based on the total weight of the aluminum sulfate suspension, the proportion of alkali metal atoms is 0.02-5% by weight, more particularly 0.05-2% by weight, especially preferably 0.1-1.4% by weight, and especially 0.2-0.7% by weight.

[0107] d) Optionally, 0.001-4% by weight, preferably 0.01-2% by weight, more particularly 0.07-1.4% by weight, especially 0.1-0.7% by weight of calcium or magnesium;

[0108] e) Optionally, 0.001-10% by weight, more particularly 0.1-5% by weight, especially 0.2-2% by weight, and very particularly preferably 0.1-0.6% by weight of iron;

[0109] f) Optionally, 0.001% to 5% by weight, preferably 0.1% to 2% by weight, or even more preferably 0.2% to 1% by weight of silicon dioxide or SiO2;

[0110] g) and water, wherein water is preferably added to a proportion of 100% by weight, particularly preferably 30-77.48% by weight, more particularly 40-70% by weight, and very particularly preferably 50-65% by weight.

[0111] Particularly preferred aluminum sulfate suspensions contain, for example (in weight percent, based on the total weight of the aluminum sulfate suspension in each case):

[0112] a) 22-46% by weight, more particularly 28-43% by weight, preferably 34-41% by weight of aluminum sulfate (Al2(SO4)3);

[0113] b) Optionally, 0.01-15% by weight, more particularly 0.05-5% by weight, especially preferably 0.1-2% by weight of aluminum hydroxide (Al(OH)3);

[0114] c) at least one soluble alkali metal compound, wherein the alkali metal is selected from sodium, potassium and / or lithium, and the amount is such that, based on the total weight of the aluminum sulfate suspension, the proportion of alkali metal atoms is 0.02-5% by weight, more particularly 0.05-2% by weight, especially preferably 0.1-1.4% by weight, and especially 0.2-0.7% by weight.

[0115] d) Optionally, 0.001-5% by weight, more particularly 0.1-2% by weight, especially 0.2-1% by weight of a calcium compound selected from calcium oxide and / or calcium hydroxide or a magnesium compound selected from magnesium oxide and / or magnesium hydroxide;

[0116] e) Optionally, 0.001-10% by weight, more particularly 0.1-5% by weight, especially 0.2-2% by weight, and very particularly preferably 0.1-0.6% by weight of iron;

[0117] f) Optionally, 0.001% to 5% by weight, preferably 0.1% to 2% by weight, or even more preferably 0.2% to 1% by weight of silicon dioxide;

[0118] g) Optionally, 0.1-15% by weight, preferably 0.1-5% by weight, especially 0.2-2% by weight of alkanolamine;

[0119] h) 0.01-10% by weight, more particularly 0.05-2% by weight, preferably 0.1-0.5% by weight of fluoride;

[0120] i) and water, wherein water is preferably added to a ratio of 100% by weight.

[0121] In a preferred embodiment, the most preferred range and substance are selected in each case.

[0122] In a particularly preferred embodiment, the aluminum sulfate suspension comprises or consists of, for example, the following components (in weight percent, based on the total weight of the aluminum sulfate suspension in each case):

[0123] a) 34-41% by weight of aluminum sulfate (Al2(SO4)3);

[0124] b) At least one soluble alkali metal compound, said alkali metal being selected from sodium, potassium and / or lithium, in an amount such that, based on the total weight of the aluminum sulfate suspension, the proportion of alkali metal atoms is 0.02-5% by weight, more particularly 0.05-2% by weight, especially preferably 0.1-1.4% by weight, especially 0.2-0.7% by weight;

[0125] c) 0.2-1 wt% of a calcium compound selected from calcium oxide and / or calcium hydroxide or a magnesium compound selected from magnesium oxide and / or magnesium hydroxide;

[0126] d) Optionally, 0.001-14.3% by weight, more particularly 0.1-7.1% by weight, especially 0.2-2% by weight of iron oxide;

[0127] e) Optionally, 0.001% to 5% by weight, preferably 0.1% to 2% by weight, even more preferably 0.2% to 1% by weight of silicon dioxide;

[0128] f) and water, wherein water is preferably added to a ratio of 100% by weight.

[0129] In another particularly preferred embodiment, the aluminum sulfate suspension comprises or consists of, for example, the following components (in weight percent, based on the total weight of the aluminum sulfate suspension in each case):

[0130] a) 34-41% by weight of aluminum sulfate (Al2(SO4)3);

[0131] b) At least one alkali metal aluminate, especially sodium aluminate and / or potassium aluminate, as at least one soluble alkali metal compound, in an amount such that the proportion of alkali metal atoms is 0.02-5% by weight, more particularly 0.05-2% by weight, especially preferably 0.1-1.4% by weight, and especially 0.2-0.7% by weight, based on the total weight of the aluminum sulfate suspension.

[0132] c) Optionally, 0.001-5% by weight, more particularly 0.1-2% by weight, especially 0.2-1% by weight of a calcium compound selected from calcium oxide and / or calcium hydroxide or a magnesium compound selected from magnesium oxide and / or magnesium hydroxide;

[0133] d) Optionally, 0.001-5% by weight, more particularly 0.1-2% by weight, especially 0.2-1% by weight of iron oxide;

[0134] e) Optionally, 0.001% to 5% by weight, preferably 0.1% to 2% by weight, even more preferably 0.2% to 1% by weight of silicon dioxide;

[0135] f) and water, wherein water is preferably added to a ratio of 100% by weight.

[0136] Another aspect of the invention relates to a method for preparing the aforementioned aluminum sulfate suspension, which is specifically designed as a coagulation and / or hardening accelerator. The aforementioned components or substances are specifically mixed to obtain an aqueous suspension. The substances can, in principle, be added in any order. The aluminum sulfate suspension according to the invention can be obtained accordingly by such a method.

[0137] The aluminum sulfate suspension available according to the present invention can be used as a curing and / or hardening accelerator to promote the setting and / or hardening of mineral binders and / or mineral binder compositions. Here, the composition is particularly mortar and / or concrete compositions, especially shotcrete and / or shotcrete.

[0138] The term "mineral binder" is specifically understood to mean a binder that reacts in a hydration reaction in the presence of water to form a solid hydrate or hydrate phase. This can be, for example, a hydraulic binder (e.g., cement or hydraulic lime), a latent hydraulic binder (e.g., slag), a pozzolanic binder (e.g., fly ash), or a non-hydraulic binder (gypsum or quicklime). "Mineral binder composition" accordingly refers to a composition containing at least one mineral binder.

[0139] Examples of mineral binders whose hardening and / or solidification can be promoted by the aluminum sulfate suspension of the present invention are cements, such as Portland cement, blended cement, alumina cement, calcium sulfoaluminate cement, and lime, hydraulic lime and gypsum, or mixtures of two or more of the aforementioned mineral binders.

[0140] More particularly, the mineral binder or binder composition comprises a hydraulic binder, preferably cement. Cement with a clinker content >35% by weight is particularly preferred. Specifically, the cement is CEM Type I, II, III, IV, or V (according to standard EN 197-1). The proportion of the hydraulic binder in the total mineral binder is advantageously at least 5% by weight, particularly at least 20% by weight, preferably at least 35% by weight, and especially at least 65% by weight. In another advantageous embodiment, at least 95% by weight of the mineral binder consists of a hydraulic binder, particularly cement clinker.

[0141] However, it may also be advantageous for the binder composition to contain other binders besides or in place of a hydraulic binder. These are particularly potential hydraulic binders and / or pozzolanic binders. Examples of suitable potential hydraulic and / or pozzolanic binders are slag, fly ash, and / or silica fume. The binder composition may also contain inert materials such as ground limestone, ground quartz, and / or pigments.

[0142] In one advantageous embodiment, the mineral binder contains 5-95% by weight, more particularly 5-65% by weight, especially 15-35% by weight of potential hydraulic and / or pozzolanic binder.

[0143] The present invention also relates to a method for promoting the curing and / or hardening of a mineral binder or mineral binder composition (e.g., mortar or concrete), wherein the above-mentioned aluminum sulfate suspension is added as a curing and / or hardening accelerator to the mineral binder or mineral binder composition in an amount of 0.1% to 15% by weight, particularly 1% to 10% by weight, and particularly preferably 4% to 8% by weight based on the weight of the mineral binder.

[0144] For example, aluminum sulfate suspension can be added to concrete or mortar compositions, particularly to shotcrete or shotcrete, where the concrete or mortar composition is used to coat a substrate. Substrates are particularly the surfaces of tunnels, mines, foundation pits, sea / lake bays, wells, and / or drainage pipes.

[0145] Aluminum sulfate suspension is preferably metered and added to shotcrete or shotcrete via dry or wet spraying methods, wherein the aluminum sulfate suspension is added to a delivery pipeline, a pre-wetted nozzle, or a dry or water-mixed binder, shotcrete, or shotcrete in the nozzle. Aluminum sulfate suspension can also be added to concrete works.

[0146] Aluminum sulfate suspension can also be added to concrete or mortar compositions, especially to shotcrete or shotcrete, where concrete or mortar compositions are used to produce free-form structures.

[0147] In addition, aluminum sulfate suspension can be mixed into concrete or mortar compositions in additive manufacturing methods, preferably by a dynamic mixer.

[0148] The present invention also relates to a curing and / or hardening accelerator for a composition comprising a mineral binder, wherein the curing and / or hardening accelerator is preferably a shotcrete accelerator, and wherein the curing and / or hardening accelerator comprises:

[0149] a) 22-46% by weight, more particularly 28-43% by weight, preferably 34-41% by weight of aluminum sulfate (Al2(SO4)3);

[0150] b) Optionally, 0.01-15% by weight, more particularly 0.05-5% by weight, especially preferably 0.1-2% by weight of aluminum hydroxide (Al(OH)3);

[0151] c) Optionally, 0.001-5% by weight, more particularly 0.1-2% by weight, especially 0.2-1% by weight of a calcium compound selected from calcium oxide and / or calcium hydroxide or a magnesium compound selected from magnesium oxide and / or magnesium hydroxide;

[0152] d) Optionally, 0.001-10% by weight, more particularly 0.1-5% by weight, especially 0.2-2% by weight, and very particularly preferably 0.1-0.6% by weight of iron;

[0153] e) Optionally, 0.001% to 5% by weight, preferably 0.1% to 2% by weight, even more preferably 0.2% to 1% by weight of silicon dioxide;

[0154] f) at least one soluble alkali metal compound, wherein the alkali metal is selected from sodium, potassium and / or lithium, and the amount is such that, based on the total weight of the aluminum sulfate suspension, the proportion of alkali metal atoms is 0.02-5% by weight, more particularly 0.05-3% by weight, especially preferably 0.1-1.4% by weight, and especially 0.2-0.7% by weight.

[0155] g) Optionally, 0.1-15% by weight, preferably 0.1-5% by weight, especially 0.2-2% by weight of alkanolamine;

[0156] h) Optionally, 0.01-10% by weight, more particularly 0.05-2% by weight, preferably 0.1-0.5% by weight of fluoride;

[0157] i) and water, wherein water is preferably added to a ratio of 100% by weight.

[0158] This curing and / or hardening accelerator preferably has a mass ratio of 1 mg / g to 100 mg / g of alkali metal atoms to aluminum sulfate (Al2(SO4)3).

[0159] An advantageous curing and / or hardening accelerator for a composition comprising a mineral binder, wherein the curing accelerator and / or hardening accelerator is preferably a shotcrete accelerator, comprising:

[0160] a) 22-46% by weight, more particularly 28-43% by weight, preferably 34-41% by weight of aluminum sulfate (Al2(SO4)3);

[0161] b) Optionally, 0.01-15% by weight, more particularly 0.05-5% by weight, especially preferably 0.1-2% by weight of aluminum hydroxide (Al(OH)3);

[0162] c) Optionally, 0.001-5% by weight, more particularly 0.1-2% by weight, especially 0.2-1% by weight of a calcium compound selected from calcium oxide and / or calcium hydroxide or a magnesium compound selected from magnesium oxide and / or magnesium hydroxide;

[0163] d) Optionally, 0.001-10% by weight, more particularly 0.1-5% by weight, especially 0.2-2% by weight, and very particularly preferably 0.1-0.6% by weight of iron;

[0164] e) Optionally, 0.001% to 5% by weight, preferably 0.1% to 2% by weight, even more preferably 0.2% to 1% by weight of silicon dioxide;

[0165] f) at least one soluble alkali metal compound, wherein the alkali metal is selected from sodium, potassium and / or lithium, and the amount is such that, based on the total weight of the aluminum sulfate suspension, the proportion of alkali metal atoms is 0.02-5% by weight, more particularly 0.05-3% by weight, especially preferably 0.1-1.4% by weight, and especially 0.2-0.7% by weight.

[0166] g) Optionally, 0.1-15% by weight, preferably 0.1-5% by weight, especially 0.2-2% by weight of alkanolamine;

[0167] h) Optionally, 0.01-10% by weight, more particularly 0.05-2% by weight, preferably 0.1-0.5% by weight of fluoride;

[0168] Water, preferably made up to 100% by weight, and wherein the mass ratio of alkali metal atoms to aluminum sulfate (Al2(SO4)3) is from 1 mg / g to 100 mg / g.

[0169] Further modifications and advantages of the present invention will be apparent to those skilled in the art based on the following working examples. Example

[0170] The following materials are used in the following embodiments:

[0171]

[0172] The proportions of Al2(SO4)3·about 14H2O described below include water of crystallization. Al2(SO4)3·about 14H2O contains 57% by weight of Al2(SO4)3. Correspondingly, water of crystallization is also included for Na2CO3·H2O.

[0173] In the NaOH and sodium aluminate solutions used, the ratio of NaOH to NaAlO2 in the following values ​​refers to NaOH and sodium aluminate themselves, excluding the water in the solution. The latter is included in H2O.

[0174] Viscosity was measured according to standard DIN EN ISO 2431:2011 using an ISO 6 cup at 23°C or an ISO 4 cup at 23°C. "nb" in the table below indicates that viscosity could not be measured. The times listed in the table are at the starting point (t=0), which is the point at which all components of the mixture have been combined.

[0175] These components can typically be added to the mixture in powder or aqueous solution form. For example, both powder form and aqueous suspension of aluminum sulfate are suitable as raw materials for aluminum sulfate.

[0176] The aluminum sulfate suspension prepared according to the present invention was found to be stable in storage for several months and to have a viscosity suitable for practical application as a shotcrete accelerator in the range of <2000 mPa·s.

[0177] Examples 1 to 4

[0178] Preparation of aluminum sulfate suspension containing sodium aluminate

[0179] Pre-fill the beaker with the specified amount of water. Then, while stirring (using a mechanical propeller stirrer at 650 rpm), add Al2(SO4)3·approximately 14H2O and sodium aluminate (0% to 4% by weight) in batches according to the order and proportions described in Table 1, and stir the suspension at room temperature for 6 hours.

[0180] Table 1: Aluminum sulfate suspension produced

[0181]

[0182] *Comparative Examples

[0183] Viscosity was measured after a specified time. Table 2 provides an overview of the results.

[0184] Table 2: Dependence of viscosity on the proportion of sodium aluminate

[0185]

[0186]

[0187] *Comparative Examples

[0188] As can be seen from Table 2, under high aluminum sulfate content, the viscosity of aluminum sulfate suspension can be significantly reduced in the first few hours by adding sodium aluminate.

[0189] Examples 5 to 8

[0190] Preparation of aluminum sulfate suspension containing sodium aluminate

[0191] The experiments were conducted in the same manner as in Examples 1 to 4, but the order of addition was changed, as shown in Table 3.

[0192] Table 3: Prepared aluminum sulfate suspension

[0193]

[0194] *Comparative Examples

[0195] Viscosity was measured after a predetermined time. Table 4 provides an overview of the results.

[0196] Table 4: Dependence of viscosity on the proportion of sodium aluminate

[0197]

[0198]

[0199] *Comparative Examples

[0200] As can be seen from Table 4, under high aluminum sulfate content, the viscosity of aluminum sulfate suspension can be significantly reduced in the first hour by adding sodium aluminate.

[0201] Examples 9 to 14

[0202] Preparation of aluminum sulfate suspension containing sodium aluminate

[0203] The experiments were conducted in the same manner as in Examples 1 to 4, but the amount and order of addition of sodium aluminate were changed, as shown in Table 5.

[0204] Table 5: Prepared aluminum sulfate suspension

[0205]

[0206] Viscosity was measured after a predetermined time. Table 6 provides an overview of the results.

[0207] Table 6: Dependence of viscosity on aluminum sulfate partitioning

[0208]

[0209]

[0210] Examples 15 to 19

[0211] Preparation of aluminum sulfate suspension containing sodium aluminate

[0212] The experiments were conducted in the same manner as in Examples 1 to 4, but with different sodium aluminate (sodium aluminate B) and the order of addition was changed, as shown in Table 7.

[0213] Table 7: Prepared aluminum sulfate suspension

[0214]

[0215] *Comparative Examples

[0216] Viscosity was measured after a predetermined time. Table 8 provides an overview of the results.

[0217] Table 8: Dependence of viscosity on sodium aluminate

[0218]

[0219]

[0220] *Comparative Example.** Values ​​are inaccurate / Measurement time is too short for ISO No. 6.

[0221] As can be seen from Table 8, at high aluminum sulfate content, the viscosity of aluminum sulfate suspension can be significantly reduced in the first few hours by adding sodium aluminate.

[0222] Examples 20 to 25

[0223] Preparation of aluminum sulfate suspension containing sodium aluminate

[0224] The experiments were conducted in the same manner as in Examples 1 to 4, but with different sodium aluminate (sodium aluminate B), as shown in Table 9.

[0225] Table 9: Prepared aluminum sulfate suspension

[0226]

[0227] *Comparative Examples

[0228] Viscosity was measured after a specified time. Table 10 provides an overview of the results.

[0229] Table 10: Dependence of viscosity on the amount of sodium aluminate

[0230]

[0231] **Value is inaccurate

[0232] As can be seen from Table 10, under high aluminum sulfate content, the viscosity of aluminum sulfate suspension can be significantly reduced in the first few hours by adding sodium aluminate.

[0233] Examples 26 to 31

[0234] Preparation of aluminum sulfate suspension containing sodium aluminate

[0235] Experiments were conducted in the same manner as in Examples 1-4, but with a different sodium aluminate (sodium aluminate B) and a different order of addition, as shown in Table 11. Furthermore, a higher concentration of aluminum sulfate was used, and a dissolving pan was used instead of a propeller stirrer for agitation. Uncorrected water loss was recorded in all experiments.

[0236] Table 11: Prepared aluminum sulfate suspension

[0237]

[0238]

[0239] *Comparative Examples

[0240] Viscosity was measured after a predetermined time. Table 12 provides an overview of the results.

[0241] Table 12: Dependence of viscosity on the amount of sodium aluminate

[0242]

[0243] *Comparative Examples

[0244] As can be seen from Table 12, by adding sodium aluminate, the viscosity of aluminum sulfate suspension can be significantly reduced in the first few hours, even at very high aluminum sulfate contents.

[0245] Examples 32 to 37

[0246] Preparation of aluminum sulfate suspension containing sodium hydroxide

[0247] The experiments were conducted in the same manner as in Examples 1 to 4, but with sodium hydroxide solution (50%) used instead of sodium aluminate as the alkali metal compound, as shown in Table 13.

[0248] Table 13: Prepared aluminum sulfate suspension

[0249]

[0250]

[0251] *Comparative Examples

[0252] Viscosity was measured after a specified time. Table 14 provides an overview of the results.

[0253] Table 14: Dependence of viscosity on the amount of NaOH

[0254]

[0255] *Comparative Examples

[0256] As can be seen from Table 14, under high aluminum sulfate content, the viscosity of aluminum sulfate suspension can be significantly reduced in the first few hours by adding NaOH.

[0257] Examples 38 to 43

[0258] Preparation of aluminum sulfate suspension containing sodium carbonate

[0259] The experiments were conducted in the same manner as in Examples 1 to 4, but sodium carbonate was used instead of sodium aluminate as the alkali metal compound, and the order of addition was changed, as shown in Table 15.

[0260] Table 15: Prepared aluminum sulfate suspension

[0261]

[0262] *Comparative Examples

[0263] Viscosity was measured after a specified time. Table 16 provides an overview of the results.

[0264] Table 16: Dependence of viscosity on the amount of Na2CO3

[0265]

[0266] *Comparative examples,**Extrapolated values

[0267] As can be seen from Table 16, under high aluminum sulfate content, the viscosity of aluminum sulfate suspension can be significantly reduced in the first few hours by adding Na2CO3.

[0268] Examples 44 to 49

[0269] Preparation of aluminum sulfate suspension containing potassium hydroxide

[0270] The experiments were conducted in the same manner as in Examples 1 to 4, but potassium hydroxide was used instead of sodium aluminate as the alkali metal compound, and the order of addition was changed, as shown in Table 17.

[0271] Table 17: Prepared aluminum sulfate suspension

[0272]

[0273] *Comparative Examples

[0274] Viscosity was measured after a specified time. Table 18 provides an overview of the results.

[0275] Table 18: Dependence of viscosity on the amount of KOH

[0276]

[0277] *Comparative examples,**Extrapolated values

[0278] As can be seen from Table 18, under high aluminum sulfate content, the viscosity of aluminum sulfate suspension can be significantly reduced in the first few hours by adding KOH.

[0279] Examples 50 to 55

[0280] Preparation of aluminum sulfate suspension containing lithium hydroxide

[0281] The experiments were conducted in the same manner as in Examples 1 to 4, but lithium hydroxide was used instead of sodium aluminate as the alkali metal compound, and the order of addition was changed, as shown in Table 19.

[0282] Table 19: Prepared aluminum sulfate suspension

[0283]

[0284] *Comparative Examples

[0285] Viscosity was measured after a specified time. Table 20 provides an overview of the results.

[0286] Table 20: Dependence of viscosity on the amount of LiOH

[0287]

[0288] *Comparative examples show that the values ​​are inaccurate, and the measurement time for ISO No. 6 is too short (i.e., the viscosity is too low for the measurement method).

[0289] As can be seen from Table 20, under high aluminum sulfate content, the viscosity of aluminum sulfate suspension can be significantly reduced in the first few hours by adding LiOH.

[0290] Examples 56 to 61

[0291] Preparation of aluminum sulfate suspension containing potassium bicarbonate

[0292] The experiments were conducted in the same manner as in Examples 1 to 4, but potassium bicarbonate was used instead of sodium aluminate as the alkali metal compound, and the order of addition was changed, as shown in Table 21.

[0293] Table 21: Prepared aluminum sulfate suspension

[0294]

[0295] *Comparative Examples

[0296] Viscosity was measured after a specified time. Table 22 provides an overview of the results.

[0297] Table 22: Dependence of viscosity on the amount of KHCO3

[0298]

[0299]

[0300] *Comparative Examples

[0301] As can be seen from Table 22, under high aluminum sulfate content, the viscosity of aluminum sulfate suspension can be significantly reduced in the first few hours by adding potassium bicarbonate.

[0302] Overview of Results

[0303] As can be seen from the examples, by adding a soluble alkali metal compound, the viscosity of the aluminum sulfate suspension can be significantly reduced in the first few hours, even at high aluminum sulfate contents. In particular, it can avoid the viscosity peak that usually occurs at the beginning.

[0304] Therefore, the viscosity of aluminum sulfate suspension can be purposefully adjusted using soluble alkali metal compounds. The order of addition and the distribution of components do not play a significant role.

[0305] All experiments were conducted at room temperature. It is well known that viscosity reduction can typically be achieved through heating, but this is undesirable due to the time and energy required. This invention uses soluble alkali metal compounds, which allows heating to a lower temperature to be sufficient or even completely avoided.

[0306] Furthermore, it has been found that the viscosity of the aluminum sulfate suspension prepared in this way can be maintained for 3 months without significant change.

[0307] The aforementioned aluminum sulfate suspension has been found to be an accelerator suitable for shotcrete and shotcrete.

[0308] While the above embodiments of the present invention are preferred, it is obvious that the present invention is not limited to these embodiments and can be modified as needed within the scope of this disclosure.

Claims

1. Use of at least one soluble alkali metal compound for reducing the viscosity of an aluminum sulfate suspension, wherein the alkali metal compound is selected from sodium aluminate.

2. The use according to claim 1, wherein the aluminum sulfate suspension is a curing accelerator and / or hardening accelerator for a composition containing a mineral binder.

3. The use according to claim 2, wherein the aluminum sulfate suspension is a shotcrete accelerator.

4. The use according to any one of claims 1 to 3, wherein the amount of the at least one alkali metal compound is selected such that the proportion of alkali metal atoms is 0.02-5 by weight based on the total weight of the aluminum sulfate suspension.

5. The use according to any one of claims 1 to 3, wherein the amount of the at least one alkali metal compound is selected such that the proportion of alkali metal atoms is 0.05-3 by weight based on the total weight of the aluminum sulfate suspension.

6. The use according to any one of claims 1 to 3, wherein the amount of the at least one alkali metal compound is selected such that the proportion of alkali metal atoms is 0.1-1.4 by weight based on the total weight of the aluminum sulfate suspension.

7. The use according to any one of claims 1 to 3, wherein the amount of the at least one alkali metal compound is selected such that the proportion of alkali metal atoms is 0.2-0.7 by weight based on the total weight of the aluminum sulfate suspension.

8. The use according to any one of claims 1 to 3, wherein the aluminum sulfate suspension has 19-40% by weight of sulfate SO4 based on the total weight of the aluminum sulfate suspension. 2- The proportion, wherein the aluminum sulfate suspension has an aluminum (Al) ratio of 3.5-10% by weight, based on the total weight of the aluminum sulfate suspension.

9. The use according to claim 8, wherein, based on the total weight of the aluminum sulfate suspension, the aluminum sulfate suspension has 24-36% by weight of sulfate SO4. 2- Proportion.

10. The use according to claim 8, wherein, based on the total weight of the aluminum sulfate suspension, the aluminum sulfate suspension has 28-34% by weight of sulfate SO4. 2- Proportion.

11. The use according to claim 8, wherein the aluminum sulfate suspension has an aluminum (Al) content of 4.5-8.7% by weight, based on the total weight of the aluminum sulfate suspension.

12. The use according to claim 8, wherein the aluminum sulfate suspension has an aluminum (Al) content of 5.4-7% by weight, based on the total weight of the aluminum sulfate suspension.

13. The use according to any one of claims 1 to 3, wherein the aluminum sulfate suspension contains 22-46% by weight of aluminum sulfate Al2(SO4)3 based on the total weight of the aluminum sulfate suspension.

14. The use according to any one of claims 1 to 3, wherein the aluminum sulfate suspension contains 28-43% by weight of aluminum sulfate Al2(SO4)3 based on the total weight of the aluminum sulfate suspension.

15. The use according to any one of claims 1 to 3, wherein the aluminum sulfate suspension contains 34-41% by weight of aluminum sulfate Al2(SO4)3 based on the total weight of the aluminum sulfate suspension.

16. The use according to any one of claims 1 to 3, wherein the aluminum sulfate suspension contains 0.01-15% by weight of aluminum hydroxide based on the total weight of the aluminum sulfate suspension.

17. The use according to any one of claims 1 to 3, wherein the aluminum sulfate suspension contains 0.1-5% by weight of aluminum hydroxide based on the total weight of the aluminum sulfate suspension.

18. The use according to any one of claims 1 to 3, wherein the aluminum sulfate suspension contains 0.2-2% by weight of aluminum hydroxide based on the total weight of the aluminum sulfate suspension.

19. The use according to any one of claims 1 to 3, wherein the molar ratio of aluminum to sulfate in the aluminum sulfate suspension is less than or equal to 0.

9.

20. The use according to any one of claims 1 to 3, wherein the molar ratio of aluminum to sulfate in the aluminum sulfate suspension is less than or equal to 0.

85.

21. The use according to any one of claims 1 to 3, wherein the molar ratio of aluminum to sulfate in the aluminum sulfate suspension is less than or equal to 0.

8.

22. The use according to any one of claims 1 to 3, wherein the molar ratio of aluminum to sulfate in the aluminum sulfate suspension is less than or equal to 0.

74.

23. The use according to any one of claims 1 to 3, wherein the molar ratio of aluminum to sulfate in the aluminum sulfate suspension is less than or equal to 0.

7.

24. The use according to any one of claims 1 to 3, wherein the molar ratio of aluminum to sulfate in the aluminum sulfate suspension is 2:

3.

25. The use according to any one of claims 1 to 3, wherein the aluminum sulfate suspension further contains 0.1-15% by weight of an alkanolamine based on the total weight of the aluminum sulfate suspension.

26. The use according to claim 25, wherein the aluminum sulfate suspension further contains 0.1-5% by weight of an alkanolamine based on the total weight of the aluminum sulfate suspension.

27. The use according to claim 25, wherein the aluminum sulfate suspension further contains 0.2-2% by weight of an alkanolamine based on the total weight of the aluminum sulfate suspension.

28. The use according to claim 25, wherein the alkanolamine is monoethanolamine, diethanolamine, triethanolamine and / or methyldiisopropanolamine.

29. The use according to any one of claims 1 to 3, wherein the alkali metal compound is added to the aluminum sulfate suspension in powder form or as an aqueous solution or during the preparation of the aluminum sulfate suspension.

30. The use according to any one of claims 1 to 3, wherein the alkali metal compound is used in combination with a calcium compound or a magnesium compound to reduce viscosity.

31. The use according to claim 30, wherein the calcium or magnesium compound is an oxide, hydroxide, carbonate, nitrate, sulfate, phosphate, halide, formate, acetate and / or citrate.

32. The use according to claim 30, wherein the calcium compound is calcium carbonate, calcium oxide and / or calcium hydroxide, and the magnesium compound is magnesium carbonate, magnesium oxide and / or magnesium hydroxide.

33. The use according to claim 30, wherein the amount of the calcium compound or magnesium compound is selected such that the proportion of calcium atoms or magnesium atoms is 0.001-4 by weight based on the total weight of the aluminum sulfate suspension.

34. The use according to claim 30, wherein the amount of the calcium compound or magnesium compound is selected such that the proportion of calcium atoms or magnesium atoms is 0.01-2 by weight based on the total weight of the aluminum sulfate suspension.

35. The use according to claim 30, wherein the amount of the calcium compound or magnesium compound is selected such that the proportion of calcium atoms or magnesium atoms is 0.07-1.4 by weight based on the total weight of the aluminum sulfate suspension.

36. The use according to claim 30, wherein the amount of the calcium compound or magnesium compound is selected such that the proportion of calcium atoms or magnesium atoms is 0.1-0.7 by weight based on the total weight of the aluminum sulfate suspension.

Images