Reducing the viscosity of aluminum sulfate suspension using alkali metal compounds

Abstract

The present invention relates to the use of at least one soluble alkali metal compound for adjusting, in particular reducing, the viscosity of an aluminium sulphate suspension, wherein this alkali metal is selected from sodium, potassium and / or lithium.

Description

Technical Field

[0001] The present invention relates to a composition for adjusting, more specifically reducing, the viscosity of an aluminum sulfate suspension. The present invention further relates to an aluminum sulfate suspension.

Background Art

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

[0003] However, non-alkali-containing accelerators are mainly used, and an aluminum sulfate suspension-based accelerator is one of the types that has been found to be particularly effective and have a good price / performance relationship. However, a problem with such accelerators is that the viscosity of the accelerator increases significantly with an increase in the active substance content. In particular, the production of the accelerator, accurate metering addition, and miscibility with the inorganic binder composition to be promoted are complicated.

[0004] International Publication No. 2005 / 075381 A1 pamphlet describes, for example, a solidification and curing accelerator containing aluminum hydroxide, aluminum sulfate, and an organic acid, where this accelerator has a molar ratio of aluminum to organic acid of less than 0.65.

[0005] European Patent No. 0 812 812 B1 specification discloses a non-alkali-containing accelerator dispersion of aluminum sulfate and alkanolamine that does not contain aluminum hydroxide.

[0006] However, a large amount of acid and alkanolamine have the disadvantage of potentially causing environmental pollution due to their leachability. They are also disadvantageous in terms of cost.

[0007] European Patent Application Publication No. 1 878 713 A1 (Construction Research and Technology GmbH) describes an accelerator for sprayed concrete or sprayed mortar 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 this dispersion is 1.35 to 0.70. The aqueous dispersion also contains an inorganic stabilizer containing magnesium silicate in the form of sepiolite. When sepiolite is used in a proportion of 0.2 to 3% by weight, the results according to European Patent Application Publication No. 1 878 713 A1 show that the dispersion is stabilized over a wide range of intended amounts of aluminum and sulfate, and the viscosity of the sprayed concrete accelerator is also favorable.

[0008] However, a drawback of such accelerators is that they require the addition of additional aluminum hydroxide to achieve a high active substance content, which increases the aluminum-to-sulfate ratio and is undesirable in some cases. This results in a relatively high cost of the accelerator due to the high price of aluminum hydroxide. Furthermore, while magnesium silicate, used as a stabilizer in the form of sepiolite, is a very good stabilizer for sprayed concrete accelerators, sepiolite has been found to be ineffective in reducing viscosity. On the contrary, the addition of sepiolite immediately after preparation consistently increases the viscosity of the aluminum sulfate suspension.

[0009] This means that while it is possible to stabilize aluminum sulfate suspensions with relatively high active substance content, it is impossible to actively influence or control the viscosity of such aluminum sulfate suspensions, especially immediately after their formation.

[0010] In the present applicant's unpublished European Patent Application No. 19207659.4, it is shown that in some cases, the reduction of viscosity of an aluminum sulfate suspension can be achieved by adding a magnesium compound.

[0011] However, there is still a demand for solutions that reduce viscosity, have improved efficacy, and are even less expensive.

[0012] Therefore, there is still a need for novel and improved solutions that overcome the aforementioned shortcomings as much as possible. [Overview of the Initiative] [Problems that the invention aims to solve]

[0013] The present invention aims to provide a solution that enables the production of an aluminum sulfate suspension having the lowest possible viscosity and the highest possible aluminum sulfate content. More specifically, it is preferable that the low viscosity is achieved immediately after the addition of the soluble alkali metal compound to the aluminum sulfate suspension, and that the low viscosity is maintained at a later point in time after the addition of the soluble alkali metal compound to the aluminum sulfate suspension. This is achieved without affecting the ratio of aluminum to sulfate, and preferably without adversely affecting the efficacy of other components of the aluminum sulfate suspension. The aluminum sulfate suspension should be particularly suitable as a highly effective solidification accelerator and / or hardening accelerator for compositions containing inorganic binders, especially for sprayed concrete or sprayed mortar, and the aluminum sulfate suspension is particularly suitable as a sprayed concrete accelerator. This solution should also be implementable by a very inexpensive and simple method. [Means for solving the problem]

[0014] Surprisingly, it was found that the object of the present invention is achieved by the use claimed in claim 1.

[0015] Therefore, at least one soluble alkali metal compound is used to adjust, or more specifically reduce, the viscosity of the aluminum sulfate suspension, where the alkali metal is selected from sodium, potassium, and / or lithium.

[0016] As shown, by using soluble alkali metal compounds, the viscosity of an aluminum sulfate suspension can be significantly reduced at the same aluminum sulfate content, and / or significantly increased at the same viscosity. Therefore, it is possible to produce a relatively inexpensive aluminum sulfate suspension with a high aluminum sulfate content and relatively low viscosity in a simple manner, which is particularly suitable as a solidification accelerator and hardening accelerator for sprayed concrete and sprayed mortar.

[0017] The use of at least one soluble alkali metal compound is particularly effective in reducing the viscosity of the aluminum sulfate suspension within a period of 1 to 48 hours, preferably 1 to 24 hours or 1 to 12 hours, more specifically 2 to 6 hours, after its addition to the aluminum sulfate suspension or after all the components for producing the aluminum sulfate suspension have been mixed together. A particular advantage is that viscosity spikes that may occur in the first few hours after the production of the aluminum sulfate suspension are attenuated, which is advantageous for economic production.

[0018] Furthermore, soluble alkali metal compounds have been shown to be effective as agents for adjusting, more specifically reducing, and / or maintaining viscosity, even at points after their addition to the aluminum sulfate suspension, more specifically 1 to 3 months later. This is especially true when the aluminum sulfate suspension contains more than 34% by weight of aluminum sulfate (Al2(SO4)3).

[0019] The use of appropriately selected soluble alkali metal compounds makes it possible to avoid changes in the ratio of aluminum to sulfate. However, the use of alkali metal aluminates can also increase the Al content in the suspension, which is usually advantageous, though not always.

[0020] Alkali metal compounds of Na, K, and Li can exhibit better efficacy than magnesium compounds. Moreover, Na and K compounds are inexpensive compared to other chemicals, thus achieving an excellent price-performance ratio. For example, problems associated with high-concentration precipitation (precipitation of magnesium sulfate) that can occur when using magnesium compounds do not occur.

[0021] Soluble alkali metal compounds can also be directly combined with conventional magnesium silicate stabilizers, particularly sepiolite, without adversely affecting the efficacy of the soluble alkali metal compounds. For example, in aluminum sulfate suspensions, magnesium silicate, particularly sepiolite, can be used in combination with soluble alkali metal compounds if necessary, thereby obtaining a particularly stable aluminum sulfate suspension with a high active substance content and low viscosity.

[0022] In addition, potentially problematic and / or expensive substances such as alkanolamines, carboxylic acids, and aluminum hydroxide can be omitted where necessary. This can be done without significantly losing the promoting effect.

[0023] Further aspects of the present invention are the subject of further independent claims. Particularly preferred embodiments of the present invention are the subject of dependent claims. [Modes for carrying out the invention]

[0024] In a first embodiment, the present invention relates to the use of at least one soluble alkali metal compound for adjusting, more specifically reducing, the viscosity of an aluminum sulfate suspension, wherein the alkali metal is selected from sodium, potassium, and / or lithium. A mixture of two or more soluble alkali metal compounds may be used, but the use of only one alkali metal compound is generally preferred for practical reasons.

[0025] The "aluminum sulfate suspension" is, more specifically, a heterogeneous mixture of a liquid, which is water, and particles of aluminum sulfate finely dispersed therein. It is preferably an aqueous aluminum sulfate suspension. Not only the particulate form of aluminum sulfate, but also a part of aluminum sulfate may be in a dissolved and / or chemically modified form, more specifically, it may be an aqueous aluminum sulfate suspension. An example of the chemically modified form of aluminum sulfate is jurbanite (AlOHSO4·5H2O). The aluminum sulfate suspension is, in this context, not a pure solution, but rather, finely dispersed particles of aluminum sulfate are always present in the liquid phase, more specifically, in water. In addition to the liquid and aluminum sulfate, the aluminum sulfate suspension may further contain components that may be in dissolved and / or solid form.

[0026] The aluminum sulfate suspension is particularly preferably a curing accelerator and / or a hardening accelerator for an inorganic binder (mineral binder), particularly a spraying concrete accelerator. Correspondingly, a soluble alkali metal compound is preferably used to adjust the viscosity of an aluminum sulfate suspension-based curing accelerator and / or hardening accelerator for a composition containing an inorganic binder such as cement, where the aluminum sulfate suspension is preferably a spraying concrete accelerator for spraying concrete or spraying mortar.

[0027] The notation "curing accelerator and / or hardening accelerator" more specifically represents a substance that brings about an increase in the compressive strength of an inorganic binder after a specified time after mixing, more specifically, within a time of 2 minutes to 24 hours after mixing, when an inorganic binder is added and compared with a blank sample that does not contain the additive / substance accelerator.

[0028] The "soluble alkali metal compound" is, in this context, an alkali metal compound that is soluble at least to the extent of about 5 g at 25 °C and a pressure of 1 bar in 1 liter of distilled water adjusted to pH 2 with HCl.

[0029] More specifically, in this context, "adjusting viscosity" means that the viscosity of the aluminum sulfate suspension is controlled and / or adjusted by a soluble alkali metal compound. More specifically, the presence of a soluble alkali metal compound alters or reduces the viscosity of the aluminum sulfate suspension compared to the viscosity of an aluminum sulfate suspension that does not contain a soluble alkali metal compound but is otherwise equivalent in composition.

[0030] Viscosity is measured more specifically in accordance with the standard DIN EN ISO 2431:2011. This is preferably done using an ISO No. 6 or No. 4 cup and at a temperature of 23°C.

[0031] Unless otherwise specified, the weight and molar ratios in each case are based on a ready-to-use aluminum sulfate suspension after viscosity adjustment. More specifically, the ready-to-use aluminum sulfate suspension is designed for direct use as a solidification accelerator and / or curing accelerator. The ready-to-use aluminum sulfate suspension therefore contains, in addition to aluminum sulfate and liquid, at least one soluble alkali metal compound and any further components that may be present.

[0032] Aluminum sulfate suspensions are preferably chloride-free. Furthermore, even though alkali metal compounds are used, aluminum sulfate suspensions are preferably alkali-free or have low alkalinity.

[0033] Typically, in building chemistry, "alkali-free" means a composition containing less than 1% by weight of alkali metal ions and / or alkaline earth metal ions, calculated as sodium oxide equivalents (Na2O) based on the total weight of the composition or the total weight of the aluminum sulfate suspension. Here, "low alkali" means a composition containing 5% by weight or less of alkali metal ions and / or alkaline earth metal ions, calculated as sodium oxide equivalents (Na2O) based on the total weight of the composition or the total weight of the aluminum sulfate suspension.

[0034] The Na2O equivalent refers to the weight of all alkali metal ions (especially Na and K) that would be present if they were all in the form of Na2O.

[0035] Typically, in building chemistry, "chloride-free" means a composition that contains less than 0.1% by weight of chloride ions, based on the total weight of the composition or the total weight of the aluminum sulfate suspension.

[0036] Soluble alkali metal compounds are used, more specifically, to adjust viscosity, and more specifically, to reduce viscosity.

[0037] More specifically, soluble alkali metal compounds are used to adjust, more specifically to reduce the viscosity of aluminum sulfate suspension, and the adjustment, more specifically, reduction of viscosity is preferably completed within a period of 1 to 168 hours, more preferably 1 to 48 hours, and especially within a period of 1 to 24 hours, after the aluminum sulfate suspension to which the soluble alkali metal compound has been added is obtained. In particular, the soluble alkali metal compound can reduce the viscosity of the aluminum sulfate suspension within a period of 1 to 6 hours after the addition of the aluminum sulfate suspension or after all the components for producing the aluminum sulfate suspension have been mixed, which is a particular advantage in production.

[0038] In particular, once the viscosity is adjusted, it remains stable over a long period, more specifically over several months. Soluble alkali metal compounds are therefore particularly used to adjust, or more specifically reduce, the viscosity of an aluminum sulfate suspension after the aluminum sulfate suspension to which the soluble alkali metal compound has been added, over a period of several months, very preferably over 1 to 3 months. This is especially true for aluminum sulfate suspensions having a proportion of more than 34% by weight of aluminum sulfate (Al2(SO4)3).

[0039] Since the viscosity of the soluble alkali metal compound can be adjusted, or more specifically reduced, within a period of 1 to 168 hours, preferably 1 to 48 hours, and particularly within a period of 6 to 24 hours, after the aluminum sulfate suspension to which the soluble alkali metal compound has been added is obtained, the viscosity of the aluminum sulfate suspension can be adjusted to a desired value even immediately after its formation. This allows for shorter formation times, as the aluminum sulfate suspension can be used as intended, more specifically, as a solidification accelerator and / or curing accelerator, within a few hours after its formation.

[0040] Furthermore, since the viscosity of the aluminum sulfate suspension to which the soluble alkali metal compound has been added can be adjusted, or more specifically reduced, over a long period of time, more specifically over a period of several months, it is possible to achieve a long-term reduction in viscosity. Therefore, it is possible to store an aluminum sulfate suspension with substantially constant viscosity for long periods of time as needed.

[0041] Soluble alkali metal compounds can therefore be used in methods for adjusting the viscosity of aluminum sulfate suspensions.

[0042] Further aspects of the present invention are methods for adjusting, more specifically reducing, the viscosity of an aluminum sulfate suspension, preferably within a period of 1 to 168 hours, preferably within 1 to 48 hours, and particularly within a period of 6 to 24 hours, after an aluminum sulfate suspension to which a soluble alkali metal compound has been added has been obtained, and / or for adjusting, more specifically reducing, the viscosity over a long period of time, more specifically over a period of several months: (a) First, the step of charging an aqueous preparation of aluminum sulfate, and (b) The step of mixing in at least one soluble alkali metal compound. (c) Optionally, the step of mixing in further aluminum sulfate. A method for obtaining an aluminum sulfate suspension, including the following: or (a) First, the step of charging an aqueous preparation of a soluble alkali metal compound, and (b) A step of mixing in aluminum sulfate to obtain an aluminum sulfate suspension. This method includes [something].

[0043] All variations are possible. In some cases, the alternating addition of individual components is a preferred method. In this context, the preparation is a solution or suspension. An aqueous preparation is therefore a solution or suspension in water.

[0044] Aqueous preparations of aluminum sulfate are solutions or suspensions of aluminum sulfate in water. In aqueous preparations, some aluminum sulfate may be present in a dissolved form, and some in a suspended form.

[0045] The solidification accelerator and / or hardening accelerator according to the present invention for compositions containing a hydraulic binder, particularly for sprayed concrete or sprayed mortar, is an aluminum sulfate suspension.

[0046] Soluble alkali metal compounds can be directly added to aluminum sulfate preparations during their formation. However, it is also possible to add soluble alkali metal compounds to aluminum sulfate preparations immediately after their formation, for example, within one hour of formation. Finally, it is also possible to add soluble alkali metal compounds to aluminum sulfate preparations only after a long period of time has passed since their formation, for example, five days or more.

[0047] The soluble alkali metal compound is preferably a basic alkali metal compound. This means that when added to acidified water, the soluble alkali metal compound can raise the pH of distilled water adjusted to pH 2 with HCl at 25°C and a pressure of 1 bar.

[0048] The soluble alkali metal compounds preferably include alkali metal salts and / or alkali metal complexes.

[0049] The soluble alkali metal compounds used in accordance with the present invention enable the formulation of highly effective solidification and / or hardening accelerators that are substantially free of calcium. Since calcium can sometimes delay the reaction or dissolution of cement clinker, solidification and / or hardening accelerators that are substantially free of calcium can be advantageous.

[0050] The alkali metal in alkali metal compounds is selected from sodium, potassium, and / or lithium, with sodium and / or potassium being preferred.

[0051] In particular, soluble alkali metal compounds include aluminates, oxides, hydroxides, carbonates, bicarbonates, nitrates, sulfates, phosphates, halides, formates, acetates, citrates, thiocyansates, silicates, or mixtures thereof.

[0052] More preferably, the soluble alkali metal compound is an aluminate, oxide, hydroxide, carbonate, bicarbonate, nitrate, formate, acetate, citrate, or a mixture thereof.

[0053] 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 a mixture thereof, with sodium or potassium compounds being preferred. Most preferably, the alkali metal compound is selected from sodium aluminate, sodium carbonate, sodium bicarbonate, sodium oxide, sodium hydroxide, potassium aluminate, or a mixture thereof.

[0054] These alkali metal compounds proved particularly advantageous in this context because they enabled a significant reduction in viscosity without adversely affecting further components. Moreover, these substances are readily available.

[0055] In principle, however, it is also possible to use other soluble alkali metal compounds.

[0056] At least one soluble alkali metal compound, more specifically, the above-mentioned soluble alkali metal compound, may be added to or during the preparation of an aluminum sulfate suspension, for example, in powder form or as an aqueous solution. Sodium aluminate may be added, for example, in powder or aqueous solution.

[0057] Preferably, the amount of soluble alkali metal compound is selected such that the alkali metal atoms are present in a proportion of 0.02 to 5% by weight, more specifically 0.05 to 2% by weight, particularly preferably 0.1 to 1.4% by weight, and especially 0.2 to 0.7% by weight, based on the total weight of the aluminum sulfate suspension.

[0058] These amounts allow for particularly good viscosity reduction without causing any significant adverse effects on the solidification accelerator and / or curing accelerator properties of the aluminum sulfate suspension.

[0059] Aluminum sulfate suspension is based on the total weight of the aluminum sulfate suspension and contains 19-40% by weight, more specifically 24-36% by weight, and especially 28-34% by weight of sulfuric acid. ion (SO4 2- ) has a proportion of

[0060] It is even more preferable that the aluminum sulfate suspension has an aluminum (Al) content of 3.5 to 10% by weight, more specifically 4.5 to 8.7% by weight, and particularly 5.4 to 7% by weight, based on the total weight of the aluminum sulfate suspension.

[0061] With such proportions of aluminum and sulfate, it is possible to produce an aluminum sulfate suspension with a high content of active substances that exhibits particularly good acceleration of solidification and / or hardening.

[0062] The aluminum sulfate suspension preferably comprises aluminum sulfate, aluminum sulfate hydroxide, sulfuric acid, aluminum hydroxide, and / or aluminum carbonate hydroxide. Aluminum sulfate is particularly preferred.

[0063] The sulfates in the aluminum sulfate suspension are derived particularly from aluminum sulfate, aluminum sulfate hydroxide, and / or sulfuric acid. Aluminum sulfate is particularly preferred. In other words, the accelerator contains, more specifically, at least one of the substances described as sources of sulfates.

[0064] The aluminum in the accelerator is preferably derived from aluminum sulfate, aluminum sulfate hydroxide, aluminum hydroxide, and / or aluminum carbonate hydroxide. Aluminum sulfate is particularly preferred. In other words, the accelerator contains, more specifically, at least one of the substances listed as sources of aluminum.

[0065] In a favorable embodiment, the aluminum sulfate suspension contains 22-46% by weight, more specifically 28-43% by weight, preferably 34-41% by weight, of aluminum sulfate (Al2(SO4)3) based on the total weight of the aluminum sulfate suspension.

[0066] The aluminum sulfate available for production may contain varying amounts of crystal water. Typically, the aluminum sulfate used is aluminum tetrahydrate (Al2(SO4)3·approximately 14H2O). This is also known as 17% aluminum sulfate because it typically contains approximately 17% Al2O3.

[0067] Unless otherwise specified, the amounts of aluminum sulfate stated in this document are based on Al2(SO4)3 without crystal water in each example. The amounts for various reference compounds can be easily converted by referring to the following relationship: Al2(SO4)3·approximately 14H2O contains 57% by weight of Al2(SO4)3 or 17% by weight of Al2O3.

[0068] Aluminum sulfate can also be produced by the reaction of aluminum hydroxide and / or aluminum metal with sulfuric acid during the formation of an aluminum sulfate suspension, accompanied by the formation of corresponding sulfate ions in aqueous solution. Generally, aluminum sulfate can be produced by the reaction of basic aluminum compounds and / or aluminum metal with sulfuric acid.

[0069] In a further advantageous embodiment, the aluminum sulfate suspension contains 0.01 to 15% by weight, more specifically 0.05 to 5% by weight, and particularly preferably 0.1 to 2% by weight, of aluminum hydroxide based on the total weight of the aluminum sulfate suspension.

[0070] Therefore, for example, it is possible to effectively increase the aluminum content of an aluminum sulfate suspension independently of the sulfate content.

[0071] Aluminum hydroxide can be used in amorphous and / or crystalline forms. Using amorphous aluminum hydroxide is advantageous, particularly because crystalline aluminum hydroxide typically only reacts sufficiently at temperatures above 130°C and pressures above 1 bar. Aluminum hydroxide can also be used in forms such as aluminum carbonate hydroxide and aluminum sulfate hydroxide.

[0072] In advantageous embodiments, the molar ratio of aluminum to sulfate in the aluminum sulfate suspension is 0.9 or less, preferably 0.85 or less, more preferably 0.8 or less, even more preferably 0.74 or less, and most particularly preferably 0.7 or less, and the molar ratio of aluminum to sulfate is particularly 2:3. In this case, the aluminum sulfate suspension can be produced particularly simply by suspending aluminum sulfate (Al2(SO4)3). The use of soluble alkali metal compounds in the present invention therefore makes it possible to produce aluminum sulfate suspensions having a high active substance content and low viscosity.

[0073] In a further advantageous embodiment, the molar ratio of aluminum to sulfate in the aluminum sulfate suspension is in the range of 0.5 to 2, preferably 0.67 to 1.35, and particularly 0.7 to 1.0. Such an aluminum sulfate suspension has improved efficacy for certain applications.

[0074] The aluminum sulfate suspension preferably has a water content of 30-80% by weight, more specifically 40-70% by weight, and preferably 50-65% by weight, based on the total weight of the aluminum sulfate suspension. Crystalline water in the components of the aluminum sulfate suspension, such as crystalline water derived from aluminum sulfate, is included in the calculations herein.

[0075] In a further advantageous embodiment, soluble alkali metal compounds are used to reduce viscosity in combination with magnesium compounds, calcium compounds, and / or iron compounds. In particular, both calcium and iron compounds are used. Although not bound by any particular theory, it is assumed that calcium and iron compounds further enhance the effect of soluble alkali metal compounds. In a particularly preferred embodiment, soluble alkali metal compounds for reducing the viscosity of an aluminum sulfate suspension are used in combination with magnesium compounds.

[0076] Magnesium compounds, calcium compounds, and / or iron compounds are particularly oxides, hydroxides, carbonates, nitrates, sulfates, phosphates, halides, formates, acetates, and / or citrates.

[0077] The magnesium compound, calcium compound, and / or iron compound are preferably oxides, hydroxides, carbonates, nitrates, formates, acetates, and / or citrates.

[0078] The calcium compound is particularly preferably calcium carbonate, calcium oxide, and / or calcium hydroxide. Calcium oxide is particularly preferred. The magnesium compound is particularly preferably magnesium carbonate, magnesium oxide, and / or magnesium hydroxide.

[0079] The calcium compound is particularly Ca(OH)2, CaCO3, and / or CaO. CaO is particularly preferred. The magnesium compound is particularly Mg(OH)2, MgCO3, and / or MgO. MgO is particularly preferred.

[0080] The amount of the calcium compound or magnesium compound is selected such that the calcium atoms or magnesium atoms constitute 0.001 to 4% by weight, preferably 0.01 to 2% by weight, more specifically 0.07 to 1.4% by weight, and especially 0.1 to 0.7% by weight, based on the total weight of the aluminum sulfate suspension.

[0081] When CaO is used as the calcium compound, the proportion of CaO based on the total weight of the aluminum sulfate suspension is advantageously 0.001 to 5% by weight, preferably 0.01 to 3% by weight, more specifically 0.1 to 2% by weight, and particularly 0.2 to 1% by weight. When MgO is used as the magnesium compound, the proportion of MgO based on the total weight of the aluminum sulfate suspension is advantageously 0.001 to 5% by weight, preferably 0.01 to 3% by weight, more specifically 0.1 to 2% by weight, and particularly 0.2 to 1% by weight.

[0082] The iron compound is particularly preferably iron oxide. Specifically, the iron compound is Fe2O3.

[0083] The amount of the iron compound is selected such that the iron atoms are present in a proportion of 0.001 to 10% by weight, more specifically 0.1 to 5% by weight, particularly 0.2 to 2% by weight, and very preferably 0.1 to 0.6% by weight, based on the total weight of the aluminum sulfate suspension.

[0084] When Fe2O3 is used as the iron compound, the proportion of Fe2O3 based on the total weight of the aluminum sulfate suspension is favorably 0.001–14.3% by weight, more specifically 0.1–7.1% by weight, and especially 0.2–2% by weight.

[0085] In a further advantageous embodiment, the aluminum sulfate suspension contains silica.

[0086] In this document, the term "silica" means not only orthosilicic acid but also all forms of silicon dioxide, namely anhydride of orthosilicic acid, actual silicon dioxide, and silica including colloidal, precipitated or fumed silica or silica fume. Silica is preferably silicon dioxide or SiO2.

[0087] It is preferable that silica is present in an amount such that the silicon dioxide content based on the total weight of the aluminum sulfate suspension is 0.001% to 5% by weight, preferably 0.1% to 2% by weight, and more preferably 0.2% to 1% by weight.

[0088] In addition, with respect to the preparation of the aluminum sulfate suspension, at least one further metal salt with a valency of divalent or higher, more specifically a metal sulfate, can be used in an amount preferably 0.1 to 5% by weight based on the total weight of the aluminum sulfate suspension. A particularly preferred further metal sulfate is manganese(II) sulfate. Iron sulfate is equally suitable.

[0089] It may be even more advantageous if the aluminum sulfate suspension further contains 0.1 to 15% by weight, preferably 0.1 to 5% by weight, and particularly 0.2 to 2% by weight, of an alkanolamine based on the total weight of the aluminum sulfate suspension. The alkanolamines used are preferably monoethanolamine, diethanolamine, triethanolamine, and / or methyldiisopropanolamine.

[0090] The aluminum sulfate suspension may further contain stabilizers, such as bentonite, palygorskite (e.g., Actigel 208), kaolin and / or magnesium silicate, such as sepiolite. The aluminum sulfate suspension according to the present invention is preferably free from organic plasticizers, particularly polycarboxylates, polycarboxylate esters and / or polycarboxylate ethers.

[0091] The aluminum sulfate suspension may contain magnesium silicate, particularly sheet silicate and / or phyllosilicate, such as sepiolite and / or bentonite. If present, the proportion of magnesium silicate is favorably 0.001 to 5% by weight, preferably 0.1 to 2% by weight, and particularly 0.2 to 1% by weight, based on the total weight of the aluminum sulfate suspension. In this context, magnesium silicate is inert or insoluble under the above definition of solubility and contributes to phase stabilization.

[0092] In addition, soluble alkali metal compounds may be used in combination with magnesium silicate to adjust, more specifically reduce, the viscosity of the aluminum sulfate suspension, and for parallel stabilization. Magnesium silicate may be sheet silicate and / or phyllosilicate, such as sepiolite and / or bentonite. Sepiolite is particularly preferred. Magnesium silicate, especially sepiolite, is preferably used in a proportion of 0.001 to 5% by weight, more preferably 0.1 to 2% by weight, and especially 0.2 to 1% by weight, based on the total weight of the aluminum sulfate suspension. The amount of soluble alkali metal compound is preferably selected such that the alkali metal atoms are present in a proportion of 0.02 to 5% by weight, more specifically 0.05 to 2% by weight, particularly preferably 0.1 to 1.4% by weight, and especially 0.2 to 0.7% by weight, based on the total weight of the aluminum sulfate suspension.

[0093] The aluminum sulfate suspension may, of course, contain further components. These may, in particular, be fluorine compounds, such as hydrofluoric acid, alkali metal fluorides, and / or fluorocomplexes. These may, for example, allow for a further increase in the promoting effect.

[0094] In particular, the aluminum sulfate suspension contains 0.01 to 10% by weight, more specifically 0.05 to 2% by weight, preferably 0.1 to 0.5% by weight, of fluoride based on the total weight of the aluminum sulfate suspension. This may enhance the promoting effect of the aluminum sulfate suspension.

[0095] The aforementioned substances exist more specifically as ions in solution, at least partially. However, they may also exist in complexed or undissolved forms, for example, in an aluminum sulfate suspension.

[0096] Particularly advantageous aluminum sulfate suspensions include, for example, the following components, or consist of these components (by weight %), based on the total weight of the aluminum sulfate suspension in each case: (a) 19% to 40% by weight, more specifically 24 to 36% by weight, and especially 28 to 34% by weight of sulfates; (b) 3.5–10% by weight, more specifically 4.5–8.7% by weight, and especially 5.4–7% by weight of aluminum; (c) A soluble alkali metal compound in which the alkali metal is selected from sodium, potassium and / or lithium, in an amount such that the alkali metal atoms are present in a proportion of 0.02 to 5% by weight, more specifically 0.05 to 2% by weight, particularly preferably 0.1 to 1.4% by weight, and especially 0.2 to 0.7% by weight, based on the total weight of the aluminum sulfate suspension; (d) optionally 0.001 to 4% by weight, preferably 0.01 to 2% by weight, more specifically 0.07 to 1.4% by weight, and especially 0.1 to 0.7% by weight of calcium or magnesium; (e) optionally 0.001 to 10% by weight of iron, more specifically 0.1 to 5% by weight, particularly 0.2 to 2% by weight, and very preferably 0.1 to 0.6% by weight of iron; (f) optionally 0.001% to 5% by weight, preferably 0.1% to 2% by weight, and more preferably 0.2% to 1% by weight of silicon dioxide or SiO2; and (g) Water, preferably water in a proportion up to 100% by weight, particularly preferably 30-77.48% by weight, more specifically 40-70% by weight, and most particularly preferably 50-65% by weight.

[0097] Particularly preferred aluminum sulfate suspensions include, for example, the following (by weight %): (a) 22-46% by weight, more specifically 28-43% by weight, preferably 34-41% by weight of aluminum sulfate (Al2(SO4)3; (b) optionally 0.01 to 15% by weight, more specifically 0.05 to 5% by weight, and especially preferably 0.1 to 2% by weight of aluminum hydroxide (Al(OH)3); (c) A soluble alkali metal compound in which the alkali metal is selected from sodium, potassium and / or lithium, in an amount such that the alkali metal atoms are present in a proportion of 0.02 to 5% by weight, more specifically 0.05 to 2% by weight, particularly preferably 0.1 to 1.4% by weight, and especially 0.2 to 0.7% by weight, based on the total weight of the aluminum sulfate suspension; (d) optionally 0.001 to 5% by weight, more specifically 0.1 to 2% by weight, and especially 0.2 to 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; (e) optionally 0.001 to 10% by weight of iron, more specifically 0.1 to 5% by weight, particularly 0.2 to 2% by weight, and very preferably 0.1 to 0.6% by weight of iron; (f) optionally 0.001% to 5% by weight, preferably 0.1% to 2% by weight, and more preferably 0.2% to 1% by weight of silicon dioxide; (g) Optionally, 0.1 to 15% by weight, preferably 0.1 to 5% by weight, and especially 0.2 to 2% by weight of an alkanolamine; (h) 0.01 to 10% by weight, more specifically 0.05 to 2% by weight, preferably 0.1 to 0.5% by weight of fluoride; and (i) Water, preferably in a proportion of up to 100% by weight.

[0098] In preferred embodiments, the most preferred range and substance are selected in each case.

[0099] In a particularly preferred embodiment, the aluminum sulfate suspension comprises, or consists of, the following components (by weight %), in each case based on the total weight of the aluminum sulfate suspension: (a) 34-41% by weight of aluminum sulfate (Al2(SO4)3; (b) A soluble alkali metal compound in which the alkali metal is selected from sodium, potassium and / or lithium, in an amount such that the alkali metal atoms are present in a proportion of 0.02 to 5% by weight, more specifically 0.05 to 2% by weight, particularly preferably 0.1 to 1.4% by weight, and especially 0.2 to 0.7% by weight, based on the total weight of the aluminum sulfate suspension; (c) 0.2 to 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; (d) optionally 0.001 to 14.3% by weight, more specifically 0.1 to 7.1% by weight, and especially 0.2 to 2% by weight of iron oxide; (e) optionally 0.001% to 5% by weight, preferably 0.1% to 2% by weight, more preferably 0.2% to 1% by weight of silicon dioxide; and (f) Water, preferably in a proportion of up to 100% by weight.

[0100] In a further particularly preferred embodiment, the aluminum sulfate suspension comprises or consists of the following components (by weight %) in each case, based on the total weight of the aluminum sulfate suspension: (a) 34-41% by weight of aluminum sulfate (Al2(SO4)3; (b) At least one alkali metal aluminate, particularly sodium aluminate and / or potassium aluminate, as at least one soluble alkali metal compound, in an amount such that the alkali metal atoms are present in a proportion of 0.02 to 5% by weight, more specifically 0.05 to 2% by weight, particularly preferably 0.1 to 1.4% by weight, and especially 0.2 to 0.7% by weight, based on the total weight of the aluminum sulfate suspension; (c) optionally 0.001 to 5% by weight, more specifically 0.1 to 2% by weight, and especially 0.2 to 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; (d) optionally 0.001 to 5% by weight, more specifically 0.1 to 2% by weight, and especially 0.2 to 1% by weight of iron oxide; (e) optionally 0.001% to 5% by weight, preferably 0.1% to 2% by weight, more preferably 0.2% to 1% by weight of silicon dioxide; and (f) Water, preferably in a proportion of up to 100% by weight.

[0101] Further aspects of the present invention relate more specifically to a process for producing the above-mentioned aluminum sulfate suspension designed as a setting and / or curing accelerator. The aforementioned components or substances are more specifically mixed to obtain an aqueous suspension. The individual substances can, in principle, be added in any order. The aluminum sulfate suspension can be obtained by this type of process.

[0102] A suspension of aluminum sulfate that can be obtained according to the present invention may be used as a solidification and / or hardening accelerator to promote the setting and / or hardening of inorganic binders (mineral binders) and / or inorganic binder compositions (mineral binder compositions). The compositions are particularly mortar and / or concrete compositions, especially sprayed mortar and / or sprayed concrete.

[0103] The term "inorganic binder (mineral binder)" is understood to more specifically refer to a binder that undergoes a hydration reaction in the presence of water to form a solid hydrate or hydrate phase. This could 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 (e.g., gypsum or white lime). An "inorganic binder composition (mineral binder composition)" is, correspondingly, a composition containing at least one inorganic binder (mineral binder).

[0104] Examples of inorganic binders whose hardening and / or setting can be accelerated by the aluminum sulfate suspension of the present invention include cement, such as Portland cement, mixed cement, alumina cement, calcium sulfoaluminate cement, and lime, hydraulic lime, and gypsum, or mixtures of two or more of the above inorganic binders.

[0105] More specifically, the inorganic binder or binder composition comprises a hydraulic binder, preferably cement. A cement having a cement clinker content of more than 35% by weight is particularly preferred; more specifically, the cement is of CEM type I, II, III, IV, or V (according to standard EN 197-1). The proportion of the hydraulic binder in the total inorganic binder is advantageously at least 5% by weight, more specifically at least 20% by weight, preferably at least 35% by weight, and particularly at least 65% by weight. In a further advantageous embodiment, the inorganic binder comprises at least 95% by weight of a hydraulic binder, particularly cement clinker.

[0106] However, it may also be advantageous if the binder composition contains other binders in addition to, or instead of, the hydraulic binder. These are in particular latent hydraulic binders and / or pozzolanic binders. Suitable examples of latent hydraulic and / or pozzolanic binders are slag, fly ash and / or silica dust. The binder composition may also similarly contain inert materials, such as crushed limestone, crushed quartz and / or pigments.

[0107] In advantageous embodiments, the inorganic binder contains 5 to 95% by weight, more specifically 5 to 65% by weight, and particularly 15 to 35% by weight of a latent hydraulic and / or pozzolanic binder.

[0108] The present invention further relates to a method for accelerating the solidification and / or hardening of an inorganic binder or inorganic binder composition, such as mortar or concrete, wherein the above-mentioned aluminum sulfate suspension is added to the inorganic binder or inorganic binder composition as a solidification and / or hardening accelerator in an amount of 0.1% to 15% by weight, more specifically 1% to 10% by weight, and particularly preferably 4% to 8% by weight, based on the weight of the inorganic binder.

[0109] For example, an aluminum sulfate suspension can be added to a concrete or mortar composition, particularly to sprayed concrete or sprayed mortar, and the concrete or mortar composition is used to coat a substrate. The substrate is particularly the surface of tunnels, mines, drilling sites, ports, wells, and / or drainage outlets.

[0110] It is preferable to measure the aluminum sulfate suspension into sprayed mortar or sprayed concrete by a dry or wet spraying method, adding the aluminum sulfate suspension to the conveyor line, pre-wet nozzle, or spray nozzle containing an anhydrous or water-mixed binder, or to the sprayed mortar or sprayed concrete. Addition of the aluminum sulfate suspension at the concrete construction site is also possible.

[0111] Aluminum sulfate suspension can also be added to concrete or mortar compositions, particularly sprayed concrete or sprayed mortar, which are used in the manufacture of free-form structures.

[0112] In addition, the aluminum sulfate suspension can be mixed into the concrete or mortar composition in the additive production process, preferably by a dynamic mixer.

[0113] The present invention also relates to a solidification accelerator and / or hardening accelerator for compositions comprising an inorganic binder (mineral binder), wherein the solidification accelerator and / or hardening accelerator is preferably a spray concrete accelerator, and wherein the solidification accelerator and / or hardening accelerator is: (a) 22-46% by weight, more specifically 28-43% by weight, preferably 34-41% by weight of aluminum sulfate (Al2(SO4)3; (b) optionally 0.01 to 15% by weight, more specifically 0.05 to 5% by weight, and especially preferably 0.1 to 2% by weight of aluminum hydroxide (Al(OH)3); (c) optionally 0.001 to 5% by weight, more specifically 0.1 to 2% by weight, and especially 0.2 to 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; (d) optionally 0.001 to 10% by weight of iron, more specifically 0.1 to 5% by weight, particularly 0.2 to 2% by weight, and very preferably 0.1 to 0.6% by weight of iron; (e) optionally 0.001% to 5% by weight, preferably 0.1% to 2% by weight, and more preferably 0.2% to 1% by weight of silicon dioxide; (f) A soluble alkali metal compound in which the alkali metal is selected from sodium, potassium and / or lithium, in an amount such that the alkali metal atoms are present in a proportion of 0.02 to 5% by weight, more specifically 0.05 to 3% by weight, particularly preferably 0.1 to 1.4% by weight, and especially 0.2 to 0.7% by weight, based on the total weight of the aluminum sulfate suspension; (g) Optionally, 0.1 to 15% by weight, preferably 0.1 to 5% by weight, and especially 0.2 to 2% by weight of an alkanolamine; (h) optionally 0.01 to 10% by weight, more specifically 0.05 to 2% by weight, preferably 0.1 to 0.5% by weight of fluoride; and (i) Water, preferably in a proportion of up to 100% by weight. Includes.

[0114] Such solidification accelerators and / or hardening accelerators preferably have a mass ratio of alkali metal atoms to aluminum sulfate (Al2(SO4)3) of 1 mg / g to 100 mg / g.

[0115] A favorable solidification accelerator and / or hardening accelerator for compositions containing an inorganic binder, wherein the solidification accelerator and / or hardening accelerator is preferably a spray concrete accelerator: (a) 22-46% by weight, more specifically 28-43% by weight, preferably 34-41% by weight of aluminum sulfate (Al2(SO4)3; (b) optionally 0.01 to 15% by weight, more specifically 0.05 to 5% by weight, and especially preferably 0.1 to 2% by weight of aluminum hydroxide (Al(OH)3); (c) optionally 0.001 to 5% by weight, more specifically 0.1 to 2% by weight, and especially 0.2 to 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; (d) optionally 0.001 to 10% by weight of iron, more specifically 0.1 to 5% by weight, particularly 0.2 to 2% by weight, and very preferably 0.1 to 0.6% by weight of iron; (e) optionally 0.001% to 5% by weight, preferably 0.1% to 2% by weight, and more preferably 0.2% to 1% by weight of silicon dioxide; (f) A soluble alkali metal compound in which the alkali metal is selected from sodium, potassium and / or lithium, in an amount such that the alkali metal atoms are present in a proportion of 0.02 to 5% by weight, more specifically 0.05 to 3% by weight, particularly preferably 0.1 to 1.4% by weight, and especially 0.2 to 0.7% by weight, based on the total weight of the aluminum sulfate suspension; (g) Optionally, 0.1 to 15% by weight, preferably 0.1 to 5% by weight, and especially 0.2 to 2% by weight of an alkanolamine; (h) optionally 0.01 to 10% by weight, more specifically 0.05 to 2% by weight, preferably 0.1 to 0.5% by weight of fluoride; and The material is water, preferably containing water in a proportion up to 100% by weight, and the mass ratio of alkali metal atoms to aluminum sulfate (Al2(SO4)3) is 1 mg / g to 100 mg / g.

[0116] Further modifications and advantages of the present invention will be apparent to those skilled in the art from the following examples.

[0117] (Exemplary embodiment) The following materials were used in the following examples.

[0118] [Table 1-1]

[0119] The values ​​listed below for the proportion of Al2(SO4)3·approximately 14H2O include crystal water. Al2(SO4)3·approximately 14H2O contains 57% by weight of Al2(SO4)3. Therefore, crystal water is also present in Na2CO3·H2O.

[0120] In the NaOH and sodium aluminate solutions used, the proportions of NaOH and NaAlO2 in the values ​​described below refer only to NaOH and sodium aluminate, excluding water in the solution. The latter is contained in H2O.

[0121] Viscosity was measured according to standard DIN EN ISO 2431:2011 using an ISO No. 6 cup at 23°C or an ISO No. 4 cup at 23°C. "nd" in the table below indicates that viscosity could not be measured. The times listed in the table below relate to time t=0, the starting point when all components of the mixture are combined.

[0122] The components can generally be added to the mixture in powder form or as an aqueous solution. For example, both powdered materials and aqueous aluminum sulfate suspensions are suitable as starting materials for aluminum sulfate.

[0123] The aluminum sulfate suspension produced according to the present invention was found to be stable for storage for several months and to have a viscosity suitable for practical use as a spray concrete accelerator in the range of less than 2000 mPa·s. [Examples]

[0124] Examples 1-4 Preparation of an aluminum sulfate suspension containing sodium aluminate The specified amount of water was first placed in a beaker. Then, while stirring (650 rpm with a mechanical propeller stirrer), Al2(SO4)3·approximately 14H2O and sodium aluminate (0% to 4% by weight) were added in several batches in the order and proportions shown in Table 1, and the suspension was stirred at room temperature for 6 hours.

[0125] [Table 1-2]

[0126] Viscosity was measured after a specified time. Table 2 shows a summary of the results.

[0127] [Table 2]

[0128] As can be seen from Table 2, the viscosity of aluminum sulfate suspension can be significantly reduced within the first few hours by adding sodium aluminate, especially at high aluminum sulfate content levels.

[0129] Examples 5-8 Preparation of an aluminum sulfate suspension containing sodium aluminate The experiment was carried out using the same method as in Examples 1-4, but the order of addition was changed as shown in Table 3.

[0130] [Table 3]

[0131] Viscosity was measured after a specified time. Table 4 summarizes the results.

[0132] [Table 4]

[0133] As can be seen from Table 4, the viscosity of aluminum sulfate suspension can be significantly reduced within the first few hours by adding sodium aluminate, especially at high aluminum sulfate content levels.

[0134] Examples 9-14 Preparation of an aluminum sulfate suspension containing sodium aluminate The experiment was carried out using the same method as in Examples 1-4, but the amount and order of addition of sodium aluminate were changed as shown in Table 5.

[0135] [Table 5]

[0136] Viscosity was measured after a specified time. Table 6 shows a summary of the results.

[0137] [Table 6]

[0138] Examples 15-19 Preparation of an aluminum sulfate suspension containing sodium aluminate The experiment was carried out using the same method as in Examples 1-4, but a different sodium aluminate (Na B) was used, and the order of addition was changed as shown in Table 7.

[0139] [Table 7]

[0140] Viscosity was measured after a specified time. Table 8 shows a summary of the results.

[0141] [Table 8]

[0142] As can be seen from Table 8, the viscosity of aluminum sulfate suspension can be significantly reduced within the first few hours by adding sodium aluminate, especially at high aluminum sulfate content levels.

[0143] Examples 20-25 Preparation of an aluminum sulfate suspension containing sodium aluminate The experiment was carried out using the same method as in Examples 1-4, but different sodium aluminate (Na B) was used, as shown in Table 9.

[0144] [Table 9]

[0145] Viscosity was measured after a specified time. Table 10 shows a summary of the results.

[0146] [Table 10]

[0147] As can be seen from Table 10, the viscosity of aluminum sulfate suspension can be significantly reduced within the first few hours by adding sodium aluminate, especially at high aluminum sulfate content levels.

[0148] Examples 26-31 Preparation of an aluminum sulfate suspension containing sodium aluminate The experiments were carried out in the same manner as in Examples 1-4, but with the use of a different sodium aluminate (Na B aluminate) and the order of addition changed as shown in Table 11. In addition, a higher concentration of aluminum sulfate was used, and a dissolver disc was used for stirring instead of a propeller stirrer. Water loss was recorded in all experiments, but this was not compensated for.

[0149] [Table 11]

[0150] Viscosity was measured after a specified time. Table 12 shows a summary of the results.

[0151] [Table 12]

[0152] As can be seen from Table 12, the viscosity of aluminum sulfate suspension can be significantly reduced within the first few hours by adding sodium aluminate, even with a very high aluminum sulfate content.

[0153] Examples 32-37 Production of an aluminum sulfate suspension containing sodium hydroxide The experiment was carried out in the same manner as in Examples 1-4, but as shown in Table 13, sodium hydroxide solution (50%) was used as the alkali metal compound instead of sodium aluminate.

[0154] [Table 13]

[0155] Viscosity was measured after a specified time. Table 14 shows a summary of the results.

[0156] [Table 14]

[0157] As can be seen from Table 14, the viscosity of aluminum sulfate suspension can be significantly reduced within the first few hours by adding NaOH, especially at high aluminum sulfate content levels.

[0158] Examples 38-43 Production of an aluminum sulfate suspension containing sodium carbonate The experiment was carried out using the same method as in Examples 1-4, but sodium carbonate was used as the alkali metal compound instead of sodium aluminate, and the order of addition was changed as shown in Table 15.

[0159] [Table 15]

[0160] Viscosity was measured after a specified time. Table 16 shows a summary of the results.

[0161] [Table 16]

[0162] As can be seen from Table 16, the viscosity of aluminum sulfate suspension can be significantly reduced within the first few hours by adding Na2CO3, especially at high aluminum sulfate content levels.

[0163] Examples 44-49 Preparation of an aluminum sulfate suspension containing potassium hydroxide The experiment was carried out using the same method as in Examples 1-4, but potassium hydroxide was used as the alkali metal compound instead of sodium aluminate, and the order of addition was changed as shown in Table 17.

[0164] [Table 17]

[0165] Viscosity was measured after a specified time. Table 18 shows a summary of the results.

[0166] [Table 18]

[0167] As can be seen from Table 18, the viscosity of aluminum sulfate suspension can be significantly reduced within the first few hours by adding KOH, especially at high aluminum sulfate content.

[0168] Examples 50-55 Production of an aluminum sulfate suspension containing lithium hydroxide The experiment was carried out using the same method as in Examples 1-4, but lithium hydroxide was used as the alkali metal compound instead of sodium aluminate, and the order of addition was changed as shown in Table 19.

[0169] [Table 19]

[0170] Viscosity was measured after a specified time. Table 20 shows a summary of the results.

[0171] [Table 20]

[0172] As can be seen from Table 20, the viscosity of aluminum sulfate suspension can be significantly reduced within the first few hours by adding LiOH, especially at high aluminum sulfate content levels.

[0173] Examples 56-61 Production of an aluminum sulfate suspension containing potassium bicarbonate The experiment was carried out using the same method as in Examples 1-4, but potassium bicarbonate was used as the alkali metal compound instead of sodium aluminate, and the order of addition was changed as shown in Table 21.

[0174] [Table 21]

[0175] Viscosity was measured after a specified time. Table 22 shows a summary of the results.

[0176] [Table 22]

[0177] As can be seen from Table 22, the viscosity of aluminum sulfate suspension can be significantly reduced within the first few hours by adding potassium bicarbonate, especially at high aluminum sulfate content levels.

[0178] Summary of results As can be seen from the examples, the viscosity of aluminum sulfate suspensions can be significantly reduced within the first few hours by adding soluble alkali metal compounds, even with high aluminum sulfate content. In particular, the viscosity spikes that typically occur at the start can be avoided.

[0179] Therefore, soluble alkali metal compounds can be used to control the viscosity of aluminum sulfate suspensions. The order and division of the components are not important.

[0180] All experiments were conducted at room temperature. As is well known, viscosity reduction is generally achievable by heating, but this is undesirable due to the time and energy required. The use of soluble alkali metal compounds according to the present invention means that heating to lower temperatures is sufficient, or heating can be avoided altogether.

[0181] In addition, it was found that the viscosity of the aluminum sulfate suspension produced in this way could be maintained for more than three months without significant change.

[0182] The above aluminum sulfate suspension was found to be an excellent accelerator for sprayed concrete and sprayed mortar.

[0183] While the above embodiments of the present invention are preferred, it will be clear that the present invention is not limited to these embodiments and can be modified as desired within the scope of this disclosure. The inventions disclosed herein include the following embodiments: [1] Use of at least one soluble alkali metal compound to adjust, and more specifically reduce, the viscosity of an aluminum sulfate suspension, wherein the alkali metal is selected from sodium, potassium and / or lithium. [2] The aluminum sulfate suspension is a solidification accelerator and / or hardening accelerator for a composition containing a mineral binder, and the aluminum sulfate suspension is preferably a spray concrete accelerator, as described in [1] above. [3] The alkali metal compound is an aluminate, oxide, hydroxide, carbonate, bicarbonate, nitrate, sulfate, phosphate, halide, formate, citrate, thiocyanate, silicate and / or acetate, as described in [1] or [2] above. [4] The alkali metal compound is selected from 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, as described in any one of [1] to [3] above. [5] The use according to any one of [1] to [4] above, wherein the amount of the at least one alkali metal compound is selected such that the alkali metal atoms are present in a proportion of 0.02 to 5% by weight, more specifically 0.05 to 3% by weight, particularly preferably 0.1 to 1.4% by weight, and especially 0.2 to 0.7% by weight, based on the total weight of the aluminum sulfate suspension. [6] The aluminum sulfate suspension contains 19-40% by weight, more specifically 24-36% by weight, and especially 28-34% by weight of sulfate (SO4) based on the total weight of the aluminum sulfate suspension. 4 - The use according to any one of [1] to [5] above, wherein the aluminum sulfate suspension has a proportion of 3.5 to 10% by weight, more specifically 4.5 to 8.7% by weight, and particularly 5.4 to 7% by weight of aluminum (Al), based on the total weight of the aluminum sulfate suspension. [7] The aluminum sulfate suspension contains 22-46% by weight, more specifically 28-43% by weight, preferably 34-41% by weight, of aluminum sulfate (Al) based on the total weight of the aluminum sulfate suspension. 2 (SO 4 ) 3 Use as described in any one of the above [1] to [6], which contains ) [8] The use according to any one of [1] to [7] above, wherein the aluminum sulfate suspension contains 0.01 to 15% by weight, preferably 0.1 to 5% by weight, and particularly 0.2 to 2% by weight of aluminum hydroxide, based on the total weight of the aluminum sulfate suspension. [9] The use according to any one of [1] to [8] above, wherein the molar ratio of aluminum to sulfate in the aluminum sulfate suspension is 0.9 or less, preferably 0.85 or less, more preferably 0.8 or less, even more preferably 0.74 or less, and most preferably 0.7 or less, and in particular the molar ratio of aluminum to sulfate is 2:3.

[10] The aluminum sulfate suspension further contains 0.1 to 15% by weight, preferably 0.1 to 5% by weight, particularly 0.2 to 2% by weight, of an alkanolamine based on the total weight of the aluminum sulfate suspension, wherein the alkanolamine used is advantageously monoethanolamine, diethanolamine, triethanolamine and / or methyldiisopropanolamine, as described in any one of [1] to [9] above.

[11] The use according to any one of [1] to

[10] above, wherein the alkali metal compound is added to the aluminum sulfate suspension in powder form or as an aqueous solution, or added during the formation of the aluminum sulfate suspension.

[12] The use of the alkali metal compound according to any one of [1] to

[11] above, in combination with a calcium compound or a magnesium compound to reduce viscosity.

[13] The use according to any one of [1] to

[12] above, wherein the calcium compound or magnesium compound is an oxide, hydroxide, carbonate, nitrate, sulfate, phosphate, halide, formate, acetate and / or citrate.

[14] The use according to any one of [1] to

[13] above, 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.

[15] The use according to any one of [1] to

[14] above, wherein the amount of the calcium compound or magnesium compound is selected such that the calcium atoms or magnesium atoms are present in proportion to 0.001 to 4% by weight, preferably 0.01 to 2% by weight, more specifically 0.07 to 1.4% by weight, and particularly 0.1 to 0.7% by weight, based on the total weight of the aluminum sulfate suspension.

[16] A solidification accelerator and / or hardening accelerator for a composition containing a mineral binder, wherein the solidification accelerator and / or hardening accelerator is preferably a spray concrete accelerator, Solidification accelerators and / or curing accelerators for compositions containing mineral binders: (a) 22-46% by weight, more specifically 28-43% by weight, preferably 34-41% by weight of aluminum sulfate (Al 2 (SO 4 ) 3 ; (b) Optionally, 0.01 to 15% by weight, more specifically 0.05 to 5% by weight, and especially preferably 0.1 to 2% by weight of aluminum hydroxide (Al(OH) 3 ); (c) optionally 0.001 to 5% by weight, more specifically 0.1 to 2% by weight, and especially 0.2 to 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; (d) optionally 0.001 to 10% by weight of iron, more specifically 0.1 to 5% by weight, particularly 0.2 to 2% by weight, and very preferably 0.1 to 0.6% by weight of iron; (e) optionally 0.001% to 5% by weight, preferably 0.1% to 2% by weight, and more preferably 0.2% to 1% by weight of silicon dioxide; (f) A soluble alkali metal compound in which the alkali metal is selected from sodium, potassium and / or lithium, in an amount such that the atoms of the alkali metal are present in a proportion of 0.02 to 5% by weight, more specifically 0.05 to 3% by weight, particularly preferably 0.1 to 1.4% by weight, and especially 0.2 to 0.7% by weight, based on the total weight of the aluminum sulfate suspension; (g) Optionally, 0.1 to 15% by weight, preferably 0.1 to 5% by weight, and especially 0.2 to 2% by weight of an alkanolamine; (h) optionally 0.01 to 10% by weight, more specifically 0.05 to 2% by weight, preferably 0.1 to 0.5% by weight of fluoride; and (i) Water, preferably in a proportion of up to 100% by weight.

[17] The alkali metal compound is selected from 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, as described in

[16] above.

Claims

1. The use of at least one soluble alkali metal compound to adjust the viscosity of an aluminum sulfate suspension, The alkali metal is selected from sodium, potassium, lithium, or a mixture thereof. The soluble alkali metal compound is selected from 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. The amount of the at least one soluble alkali metal compound is selected such that the alkali metal atoms are present in a proportion of 0.02 to 5% by weight, based on the total weight of the aluminum sulfate suspension containing water and the soluble alkali metal compound, and The aluminum sulfate suspension contains 22 to 46% by weight of aluminum sulfate (Al₂(SO₄)₃) based on the total weight of the aluminum sulfate suspension containing water and the soluble alkali metal compound. use.

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

3. The use according to claim 1, wherein the amount of the at least one soluble alkali metal compound is selected such that the alkali metal atoms are present in a proportion of 0.05 to 3% by weight, based on the total weight of the aluminum sulfate suspension containing water and the soluble alkali metal compound.

4. The aluminum sulfate suspension contains 19 to 40% by weight of sulfate ions (SO4) based on the total weight of the aluminum sulfate suspension, which includes water and the soluble alkali metal compound. ４ The use according to claim 1, wherein the aluminum sulfate suspension has a proportion of 3.5 to 10% by weight of aluminum (Al) based on the total weight of the aluminum sulfate suspension containing water and the soluble alkali metal compound.

5. The aluminum sulfate suspension contains 28 to 43% by weight of aluminum sulfate (Al) based on the total weight of the aluminum sulfate suspension containing water and the soluble alkali metal compound. ２ (SO ４ ) ３ The use according to claim 1, which contains )

6. The use according to claim 1, wherein the aluminum sulfate suspension contains 0.01 to 15% by weight of aluminum hydroxide based on the total weight of the aluminum sulfate suspension containing water and the soluble alkali metal compound.

7. The use according to claim 1, wherein the molar ratio of aluminum to sulfate ions (SO₄²⁻) in the aluminum sulfate suspension is 0.9 or less.

8. The use according to claim 1, wherein the aluminum sulfate suspension further contains 0.1 to 15% by weight of an alkanolamine based on the total weight of the aluminum sulfate suspension containing water and the soluble alkali metal compound.

9. The use according to claim 1, wherein the soluble alkali metal compound is added to the aluminum sulfate suspension in powder form or as an aqueous solution, or is added during the formation of the aluminum sulfate suspension.

10. The use according to any one of claims 1 to 9, wherein the soluble alkali metal compound is used in combination with a calcium compound or a magnesium compound to reduce viscosity.

11. The use according to claim 10, wherein the calcium compound or magnesium compound is an oxide, hydroxide, carbonate, nitrate, sulfate, phosphate, halide, formate, acetate, citrate, or a mixture thereof.

12. The use according to claim 10, wherein the calcium compound is calcium carbonate, calcium oxide, calcium hydroxide, or a mixture thereof, or the magnesium compound is magnesium carbonate, magnesium oxide, magnesium hydroxide, or a mixture thereof.

13. The use according to claim 10, wherein the amount of the calcium compound or magnesium compound is selected such that the calcium atoms or magnesium atoms are present in a proportion of 0.001 to 4% by weight based on the total weight of the aluminum sulfate suspension containing water and the soluble alkali metal compound.

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