Mineral powder modifier, preparation method thereof and modified mineral powder

Abstract

The present invention relates to a mineral powder modifier, a preparation method thereof and modified mineral powder, and belongs to the technical field of mineral powder modification. A mineral powder modifier, the mineral powder modifier comprises the following components by mass: 70-90 parts of modified nano calcium hydroxide, 10-40 parts of an inorganic salt promoting composition and 0-10 parts of silicon dioxide; wherein the modified nano calcium hydroxide is nano calcium oxide surface-modified with a water reducing agent. By using the mineral powder modifier of the present invention, the activity of the mineral powder can be fully stimulated, the early and mid-term strength of the mineral powder can be improved, the activity of the mineral powder can be improved, the mineral powder has excellent mechanical properties, and compared with the existing modifiers, the corrosiveness can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of mineral powder modification, and in particular relates to a mineral powder modifier, a preparation method thereof and modified mineral powder. Background Art

[0002] Mineral powder is a powder of a certain fineness ground from blast furnace slag as the main raw material. Its main components include calcium, silicon, aluminum, magnesium, aluminum and its oxides, which are close to silicate clinker and are very important admixtures in the production of ready-mixed concrete. Usually, mineral powder is uniformly produced by mineral powder production enterprises, and it is stipulated that the 7d activity index of S95 slag powder is greater than 75%, and the 28-day activity index is greater than 95%. However, compared with cement, the strength of mineral powder in the early hydration process is lower, resulting in a decrease in the strength of concrete prepared by using it to replace cement, especially the early strength, thereby limiting its dosage in concrete.

[0003] Therefore, in order to increase the proportion of cement replaced by mineral powder while meeting the strength requirements, it is necessary to improve the activity or performance of mineral powder. The use of mineral powder with higher activity can further improve the quality of concrete while increasing the utilization rate of industrial waste slag and reducing production costs, which has significant practical value and environmental significance.

[0004] At present, in order to improve the performance of mineral powder, mechanical and chemical methods are more commonly used. Among them, the mechanical method is to increase the specific surface area of ​​mineral particles by mechanical grinding, thereby increasing the reaction area and reaction probability; however, when the material is ground to a certain fineness, the processing energy consumption required to continue to increase the fineness will surge, so its activity improvement level is limited. The chemical method usually uses chemicals to improve the strength of mineral powder. For example, the Chinese patent with publication number CN113831051A discloses a mineral powder grinding aid, which mainly uses sulfate, sodium hydroxide / potassium hydroxide, and aluminate to improve the activity and strength of mineral powder. However, sodium hydroxide and potassium hydroxide are highly corrosive and are likely to cause serious damage to the skin, eyes, etc. when in contact; sulfate ions will corrode metal-based materials such as steel bars. In addition, the related art also adds chlorides and alcohol amines to improve the activity of mineral powder. Similarly, chloride ions will also corrode steel bars, and alcohol amines are highly sensitive. Therefore, it is necessary to research and develop a modifier with relatively less harm or corrosiveness to increase the activity of mineral powder. Summary of the invention

[0005] In view of the above problems, the present invention aims to solve one of the technical problems in the related art to at least a certain extent. To this end, the present invention provides a mineral powder modifier, a preparation method thereof and a modified mineral powder, through which the activity of the mineral powder can be fully stimulated, the early and mid-term strength of the mineral powder can be improved, and the corrosiveness can be reduced.

[0006] As one aspect of the present invention, it relates to a mineral powder modifier, which comprises the following components in parts by weight:

[0007] 70-90 parts of modified nano calcium hydroxide, 10-40 parts of inorganic salt promoting composition and 0-10 parts of silicon dioxide;

[0008] Wherein, the modified nano calcium hydroxide is nano calcium oxide surface-modified with a water reducing agent.

[0009] In addition, the mineral powder modifier according to the present application may also have the following additional technical features:

[0010] In some embodiments, the mineral powder modifier includes the following components in parts by weight:

[0011] 75-85 parts of modified nano calcium hydroxide, 10-30 parts of inorganic salt promoting composition and 2-10 parts of silicon dioxide.

[0012] In some of the embodiments, the water reducer comprises a polycarboxylate water reducer or a modified polycarboxylate water reducer;

[0013] And / or, the inorganic salt promoting composition comprises a combination of phosphate and calcium salt.

[0014] In some embodiments, the mass ratio of the phosphate to the calcium salt is 9:1 to 5:5.

[0015] In some embodiments, the phosphate includes at least one of sodium hexametaphosphate, disodium hydrogen phosphate, or sodium polyphosphate;

[0016] And / or, the calcium salt includes at least one of calcium nitrate, calcium acetate or calcium formate.

[0017] In some embodiments, the average particle size of the modified nano calcium hydroxide is ≤100 nm;

[0018] And / or, the silicon dioxide is a silicon dioxide with a porous structure, the diameter distribution of the pores in the silicon dioxide with a porous structure is 0.5 nm to 15 nm, and the saturated water absorption capacity of the silicon dioxide with a porous structure is ≥50%.

[0019] As another aspect of the present invention, it relates to a method for preparing a mineral powder modifier, wherein the mineral powder modifier includes the aforementioned mineral powder modifier, and the method comprises:

[0020] The modified nano calcium hydroxide, the inorganic salt promoting composition and silicon dioxide in the formulated amount are uniformly mixed to obtain the mineral powder modifier.

[0021] In some embodiments, the mixing is performed in a carbon dioxide-free atmosphere.

[0022] And / or, the preparation method of the modified nano calcium hydroxide comprises:

[0023] Adding a water reducing agent to water, stirring and dispersing to form a base liquid, and adjusting the pH value of the base liquid to obtain a dispersed base liquid;

[0024] Under stirring conditions, adding a calcium compound solution and a hydroxide solution to the dispersed base liquid to obtain a calcium hydroxide-water reducing agent suspension;

[0025] The calcium hydroxide-water reducing agent suspension is dried to obtain the modified nano calcium hydroxide in powder form.

[0026] In some of the embodiments, the pH value of the base solution is 12.5 to 13;

[0027] And / or, the stirring rate of the stirring condition is 1300-4000 rpm, and the stirring is performed under a nitrogen atmosphere;

[0028] and / or, the concentration of the calcium-containing compound in the calcium-containing compound solution is 10 to 300 g / L;

[0029] And / or, the amount of the water reducing agent is 1% to 20% of the mass of the calcium-containing compound in the calcium-containing compound solution.

[0030] As another aspect of the present invention, it relates to a modified mineral powder, comprising a mineral powder main body, and also comprising the mineral powder modifier as described above or the mineral powder modifier prepared by the aforementioned preparation method;

[0031] Wherein, the added amount of the mineral powder modifier is 1% to 5% of the mass of the mineral powder body.

[0032] Compared with the prior art, the technical solution of the present application has at least the following beneficial effects:

[0033] The mineral powder modifier provided by the present application includes modified nano calcium hydroxide, an inorganic salt promoting composition and silicon dioxide, wherein the modified nano calcium hydroxide is a nano calcium oxide surface modified with a water reducing agent; by using the modified nano calcium hydroxide and silicon dioxide in combination, the dispersion can be improved, the mineral powder vitreous structure can be stimulated, and the gelling activity and volcanic ash activity of the mineral powder can be improved, thereby improving the early activity of the mineral powder; by using the inorganic salt promoting composition, the hydration can be further promoted, and the early and mid-term strength of the mineral powder can be improved, thereby achieving the strength improvement of the mineral powder. In addition, the mineral powder modifier provided by the embodiment of the present application belongs to a mineral powder modifier of a chlorine-free, sulfate-free and low-corrosion system. When it is applied to modify the mineral powder, it can also achieve a relatively effective modification effect at a low dosage, and compared with the existing mineral powder modifier or grinding aid containing components such as sodium hydroxide, it has lower corrosiveness and reduces damage.

[0034] The method of the present invention is simple and easy to implement, easy to operate, and easy to realize large-scale production. The prepared mineral powder modifier has good performance, can fully stimulate the activity of the mineral powder, and makes the mineral powder modified by the mineral powder modifier show excellent early strength, and has good application prospects.

[0035] Additional aspects and advantages of the embodiments of the present application will be described, shown, or explained in part in the subsequent description through implementation of the embodiments of the present application. DETAILED DESCRIPTION

[0036] The present application is further described below in conjunction with specific embodiments. It should be understood that these embodiments of the present application are only used to illustrate the present application and are not used to limit the scope of the present application.

[0037] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range or the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0038] In this article, unless otherwise specified, the percentages, ratios or parts involved are based on mass. Among them, "mass parts" refers to the basic unit of measurement of the mass ratio relationship of multiple components, and 1 part can represent any unit mass. In this article, unless otherwise specified, percentages (%) refer to the mass percentage relative to the composition.

[0039] As mentioned in the background technology, the modifiers or additives provided in the related art for improving the performance of mineral powders still have more or less shortcomings, such as the components used are corrosive to a certain extent, which can easily cause damage to the human body or metal-based materials, and thus need further improvement. At least based on the above insight into the prior art, this application increases the activity of mineral powder from the perspective of providing a mineral powder modifier with relatively less harm, that is, the present invention provides a mineral powder modifier with a chlorine-free, sulfate-free, low-corrosion system and a preparation method thereof. The mineral powder modifier composed of modified nano calcium hydroxide is also very effective at low dosages, and is less corrosive than sodium hydroxide; by using the mineral powder modifier, the activity of the mineral powder can be fully stimulated, showing excellent early strength. See below for a description of the specific technical solution.

[0040] In some embodiments, a mineral powder modifier is provided, wherein the mineral powder modifier comprises the following components in parts by weight:

[0041] 70-90 parts of modified nano calcium hydroxide, 10-40 parts of inorganic salt promoting composition and 0-10 parts of silicon dioxide;

[0042] Wherein, the modified nano calcium hydroxide is nano calcium oxide surface-modified with a water reducing agent.

[0043] The mineral powder modifier of this embodiment can be applied to mineral powder. By modifying the mineral powder with the mineral powder modifier, the activity of the mineral powder can be improved, the activity of the mineral powder can be fully stimulated, the performance of the mineral powder can be improved, and in particular, the mineral powder can show excellent early strength. Specifically, the mineral powder modifier is mainly composed of modified nano calcium hydroxide, an inorganic salt promoting composition and silicon dioxide. The modified nano calcium hydroxide is a nano calcium oxide surface modified with a water reducer, that is, the modified nano calcium hydroxide can be obtained by modifying calcium hydroxide with a water reducer. On the one hand, modified nano calcium hydroxide and silicon dioxide are added to the formula. Under the synergistic cooperation of the two, the dispersion of the modified nano calcium hydroxide is improved after using silicon dioxide as a water absorbent and an isolating agent, which can stimulate the vitreous structure of the mineral powder, and can improve the gelling activity and volcanic ash activity of the mineral powder, thereby improving the early activity of the mineral powder and improving the early compressive strength of the mineral powder.

[0044] On the other hand, an inorganic salt promoting composition is added to the formula, and the inorganic salt promoting composition preferably includes calcium ions and phosphate ions. The calcium ions and phosphate ions in the inorganic salt promoting composition react to generate apatite and form crystal nuclei, which can further promote hydration and further improve the early and mid-term strength of the mineral powder, thereby achieving strength improvement of the mineral powder.

[0045] At the same time, the mineral powder modifier of this embodiment, by modifying the nano calcium hydroxide, silicon dioxide and inorganic salt to promote the coordinated coordination of the composition, the obtained modifier particles are loose and fine, with high dispersion, which can effectively promote the activation of mineral powder and accelerate hydration. In addition, the mineral powder modifier provided by this embodiment belongs to a mineral powder modifier of a chlorine-free, sulfate-free and low-corrosive system. When it is used to modify the mineral powder, it can also achieve a relatively effective modification or activation effect at a low dosage, and compared with the existing mineral powder modifier or grinding aid containing components such as sodium hydroxide, it has lower corrosiveness and reduces damage.

[0046] In order to achieve better coordination of the components in the mineral powder modifier, it is more helpful to improve the activity of the mineral powder and make the mechanical properties of the mineral powder better. The mineral powder modifier includes 70 to 90 parts of modified nano calcium hydroxide by mass, and typical but non-limiting examples can be 70 parts, 72 parts, 75 parts, 78 parts, 80 parts, 82 parts, 85 parts, 88 parts, 90 parts and any value in the range formed by any two of these point values. As the core of the mineral powder modifier, the modified nano calcium hydroxide generally accounts for at least half of the mineral powder modifier. If the content of the modified nano calcium hydroxide is too low, the effect of effectively promoting the activation of the mineral powder is not good. If the content of the modified nano calcium hydroxide is too high, it may affect other properties of the material and increase the cost of raw materials. Therefore, by making the addition amount of the modified nano calcium hydroxide 70 to 90 parts, the comprehensive performance of the mineral powder modifier can be met and the cost can be reduced while ensuring the effective promotion of the activation of the mineral powder.

[0047] The mineral powder modifier includes 10 to 40 parts of the inorganic salt accelerating composition by weight, and typically but not limitedly, it can be 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, 22 parts, 25 parts, 30 parts, 35 parts, 38 parts, 40 parts, and any value in the range formed by any two of these point values. In the mineral powder modifier, adding an appropriate amount of the inorganic salt accelerating composition helps to further improve the early and mid-term strength of the mineral powder, while too much inorganic salt may have an adverse effect on the performance of the concrete containing the mineral powder, so it is necessary to control the content of the inorganic salt accelerating composition within the above range.

[0048] The mineral powder modifier includes 0 to 10 parts of silicon dioxide by mass, and typical but non-limiting examples include 0.1 parts, 1 parts, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, and any value in the range formed by any two of these point values. It should be noted that the mineral powder modifier contains 0 to 10 parts of silicon dioxide, wherein the content of silicon dioxide is preferably not 0, that is, the above content range preferably does not include 0. In the mineral powder modifier, adding an appropriate amount of silicon dioxide can act as a water absorbent and an isolating agent to improve the dispersion of the material, thereby helping to improve the early strength of the mineral powder and improve the activity of the mineral powder.

[0049] The formula of the mineral powder modifier of this embodiment is mainly composed of three parts, namely, modified nano calcium hydroxide, inorganic salt promoting composition and silicon dioxide. According to different goals and uses, the addition amount and type of each component are also different. The mineral powder modifier adjusts the type and ratio of each raw material component and cooperates with other components. By making each component within the above range, the prepared mineral powder modifier can have a good mineral powder activation effect and stable performance, which can fully stimulate the activity of the mineral powder, improve the early and mid-term strength of the mineral powder, and reduce the corrosiveness.

[0050] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0051] In some embodiments, the mineral powder modifier includes the following components in parts by weight:

[0052] 70-90 parts of modified nano calcium hydroxide, 10-40 parts of inorganic salt promoting composition and 1-10 parts of silicon dioxide.

[0053] In some embodiments, the mineral powder modifier comprises the following components in parts by mass: 75-85 parts of modified nano calcium hydroxide, 10-30 parts of inorganic salt promoting composition and 2-10 parts of silicon dioxide. In some embodiments, the mineral powder modifier comprises the following components in parts by mass: 78-82 parts of modified nano calcium hydroxide, 12-28 parts of inorganic salt promoting composition and 3-8 parts of silicon dioxide.

[0054] By rationally adjusting and optimizing the content of each component in the mineral powder modifier, the synergistic effect of the components can be fully utilized to further improve the mineral powder reduction activation performance or comprehensive performance of the mineral powder modifier, while reducing the production cost of the mineral powder modifier.

[0055] In some embodiments, the water reducer includes a polycarboxylate water reducer or a modified polycarboxylate water reducer. For example, the water reducer may be a polycarboxylate water reducer (PCE), which is a third generation high performance water reducer having the characteristics of high water reduction rate and good slump retention performance. Alternatively, the water reducer may be a modified polycarboxylate water reducer, which may be obtained by modifying a polycarboxylate water reducer by any known modification method in the related art. This embodiment does not limit the specific type or modification method of the modified polycarboxylate water reducer.

[0056] In this embodiment, a water reducing agent such as PCE and calcium hydroxide are used as raw materials, or PCE and calcium salt and hydroxide are used as raw materials to prepare modified nano calcium hydroxide. The PCE has excellent surface properties and can modify the surface of nano calcium hydroxide, that is, nano particles modified by the PCE surface can be obtained. Nano calcium hydroxide particles modified by the PCE surface have better dispersibility, which is more helpful to stimulate the activity of the mineral powder.

[0057] In some embodiments, the average particle size of the modified nano calcium hydroxide is ≤100 nm. For example, the average particle size of the modified nano calcium hydroxide is <100 nm; or, the average particle size of the modified nano calcium hydroxide is ≤80 nm; or, the average particle size of the modified nano calcium hydroxide is ≤50 nm, etc.

[0058] Therefore, the modified nano calcium hydroxide has better dispersibility and can be more evenly dispersed in the mineral powder, thereby improving the conversion efficiency and further enhancing the activity of the mineral powder.

[0059] The modified nano calcium hydroxide can be obtained through a variety of preparation methods. Exemplarily, the preparation method of the modified nano calcium hydroxide comprises: adding PCE to water, dispersing to form a base liquid, adjusting the pH of the base liquid to 12.5-13, and then adding calcium nitrate and sodium hydroxide solution to the base liquid at a molar ratio of 1:1 to form a Ca(OH)2-PCE suspension, and then preparing a modified nano calcium hydroxide powder. Further, the prepared modified nano calcium hydroxide is added with silicon dioxide to prepare a composite nanoparticle powder. When mixed with water, the composite nanoparticles are very easy to disperse again and can be more evenly dispersed in the mineral powder, thereby improving the conversion efficiency and the mechanical properties of the mineral powder.

[0060] In some embodiments, the inorganic salt promoting composition includes a combination of phosphate and calcium salts.

[0061] In this embodiment, the inorganic salt promoting composition includes calcium ions and phosphate ions. The calcium ions and phosphate ions in the inorganic salt promoting composition react to generate apatite and form crystal nuclei, which can further promote hydration and further improve the early and mid-term strength of the mineral powder, thereby achieving strength improvement of the mineral powder.

[0062] In some embodiments, the mass ratio of phosphate to calcium salt in the inorganic salt promoting composition is 9:1 to 5:5. In some embodiments, the mass ratio of phosphate to calcium salt in the inorganic salt promoting composition is 9:2 to 5:5. Exemplarily, the mass ratio of phosphate to calcium salt can be 9:1, 9:2, 9:3, 9:4, 9:5, 8:1, 7:1, 6:1, 5:1, 5:2, 5:3, 5:4, 5:5, etc.

[0063] In some embodiments, the phosphate includes, but is not limited to, at least one of sodium hexametaphosphate, disodium hydrogen phosphate, or sodium polyphosphate. For example, the phosphate can be sodium hexametaphosphate, disodium hydrogen phosphate, sodium polyphosphate, or a combination of two or more of the above options, and any combination can be used.

[0064] In some embodiments, the calcium salt includes, but is not limited to, at least one of calcium nitrate, calcium acetate, or calcium formate. For example, the calcium salt can be calcium nitrate, calcium acetate, calcium formate, or a combination of two or more of the above options, and any combination can be used.

[0065] In addition, in other embodiments, the above-mentioned phosphates and calcium salts are not limited to the types listed above. Under the condition of meeting the requirements of effectively stimulating the activity of the mineral powder and improving the mechanical properties of the mineral powder, the phosphates and calcium salts can also be of other types, which will not be described in detail one by one here.

[0066] In some embodiments, the silicon dioxide is a silicon dioxide with a porous structure, the diameter distribution of the pores in the silicon dioxide with a porous structure is 0.5nm to 15nm, and the saturated water absorption of the silicon dioxide with a porous structure is ≥50%. For example, the diameter distribution of the pores in the silicon dioxide with a porous structure can be 0.5nm to 12nm, 1nm to 10nm, etc.; the saturated water absorption of the silicon dioxide with a porous structure can be 50%, 60%, 70%, 80%, etc.

[0067] The porous silica is easier to disperse and can be used as a water absorbent and a separator, which greatly improves the dispersion. It helps to effectively stimulate the vitreous structure of the mineral powder when used in conjunction with modified nano-calcium hydroxide, thereby increasing the gelling activity and volcanic ash activity of the mineral powder, thereby increasing the early activity of the mineral powder.

[0068] Based on the same inventive concept, in some embodiments, a method for preparing a mineral powder modifier is also provided, wherein the mineral powder modifier includes the aforementioned mineral powder modifier, and the method includes:

[0069] The modified nano calcium hydroxide, the inorganic salt promoting composition and silicon dioxide in the formulated amount are uniformly mixed to obtain the mineral powder modifier.

[0070] It should be understood that the specific selection and optimized dosage of the modified nano calcium hydroxide, inorganic salt promoting composition and silicon dioxide used in the preparation method of the mineral powder modifier of the present application are the same as those defined in the mineral powder modifier described in the first aspect of the present application. Please refer to the previous description of the first aspect and will not be repeated here.

[0071] The preparation method provided in this embodiment is simple and easy to operate. It only needs to mix the raw materials evenly. It has high feasibility, relatively mild conditions, and is easy to achieve large-scale production. In addition, the prepared mineral powder modifier is applied to the mineral powder, which can fully stimulate the activity of the mineral powder, so that the mineral powder modified by the mineral powder modifier exhibits excellent early strength and improves the mechanical properties of the mineral powder.

[0072] In some embodiments, the mixing is performed in a carbon dioxide-free atmosphere. Optionally, the mixing temperature may be room temperature (eg, 18-30° C.).

[0073] In this embodiment, the modified nano calcium hydroxide, the inorganic salt promoting composition and silicon dioxide in the formula amount are mixed evenly at room temperature and in an atmosphere without carbon dioxide to prepare a mineral powder modifier. Thus, the obtained modifier particles are loose and fine, with high dispersion, which can effectively promote the activation of mineral powder and accelerate hydration.

[0074] In some embodiments, the preparation method of the modified nano calcium hydroxide comprises the following steps:

[0075] S1. Add a water reducing agent such as PCE to water, stir and disperse to form a base liquid, and adjust the pH value of the base liquid to alkaline to obtain a dispersed base liquid. Optionally, the stirring can be low-speed stirring, and care should be taken to avoid the formation of foam during stirring.

[0076] S2. Under stirring conditions, the calcium compound solution and the hydroxide solution are added to the dispersed bottom liquid to obtain a calcium hydroxide-water reducing agent suspension. Optionally, the stirring needs to be carried out under a protective atmosphere such as a nitrogen atmosphere, and the stirring can be vigorous stirring.

[0077] Optionally, the calcium compound solution may be a calcium nitrate solution, and the hydroxide solution may be a sodium hydroxide solution.

[0078] It should be noted that the present embodiment has no special requirements for the specific types of the above-mentioned calcium-containing compound solution and hydroxide solution, as long as the two can react to generate calcium hydroxide. The following mainly takes the calcium-containing compound solution as a calcium nitrate solution and the hydroxide solution as a sodium hydroxide solution as an example for explanation, of course, it is not limited to this, in other embodiments, other types of calcium-containing compounds and hydroxides can also be used, which are not listed here one by one.

[0079] S3, drying the calcium hydroxide-water reducing agent suspension to obtain the modified nano calcium hydroxide in powder form. Optionally, before drying, the calcium hydroxide-water reducing agent suspension is first filtered. Optionally, the drying can be freeze drying, or the drying can also be vacuum drying.

[0080] In some embodiments, in step S1, the pH value of the base solution is adjusted to 12.5-13; for example, the pH value of the base solution can be 12.5, 12.6, 12.7, 12.8, 13, etc.

[0081] In some embodiments, in step S2, the stirring condition has a stirring rate of 1300-4000 rpm, and the stirring is performed under a nitrogen atmosphere. For example, the stirring rate may be 1300-3800 rpm, or the stirring rate may be 1500-3500 rpm, or the stirring rate may be 2000-3000 rpm, etc.

[0082] In some embodiments, the concentration of the calcium compound in the calcium compound solution is 10 to 300 g / L. For example, when the calcium compound solution is a calcium nitrate solution, the concentration of calcium nitrate in the calcium nitrate solution is 30 to 280 g / L, further 50 to 250 g / L, further 100 to 200 g / L, etc.

[0083] In some embodiments, the amount of the water reducing agent is 1% to 20% of the mass of the calcium-containing compound in the calcium-containing compound solution. For example, when preparing modified nano calcium hydroxide, the amount of the water reducing agent PCE added is 1% to 20% of the mass of the calcium nitrate in the calcium nitrate solution, further 1% to 20%, further 2% to 15%, further 5% to 10%, etc.

[0084] In some specific embodiments, the preparation method of modified nano calcium hydroxide comprises the following steps:

[0085] S1. Preparation of dispersed base liquid: add a water reducing agent such as PCE to water, stir and disperse at a low speed to form a base liquid, and pay attention to avoid the formation of foam as much as possible, adjust the pH value of the base liquid to 12.5-13, and obtain a dispersed base liquid.

[0086] S2. Preparation of calcium hydroxide-water reducer suspension: A protective gas such as nitrogen is introduced into the reactor, and under vigorous stirring conditions, such as a stirring rate of 1300 to 4000 rpm, a prepared calcium compound solution such as a calcium nitrate solution and a hydroxide solution such as a sodium hydroxide solution are added dropwise to the dispersed base liquid obtained in step S1 at a molar ratio of 1:1 to obtain a calcium hydroxide-water reducer (Ca(OH)2-PCE) suspension. The concentration of calcium nitrate in the calcium nitrate solution is 10 to 300 g / L.

[0087] S3, filtering the calcium hydroxide-water reducing agent PCE suspension obtained in step S2 to remove most of the water, and then freeze-drying or vacuum-drying it to obtain a powder, thereby obtaining powdered modified nano calcium hydroxide.

[0088] Based on the same inventive concept, the embodiment of the present application further provides a modified mineral powder, including a mineral powder main body, and also including the mineral powder modifier as described above or the mineral powder modifier prepared by the aforementioned preparation method;

[0089] Wherein, the added amount of the mineral powder modifier is 1% to 5% of the mass of the mineral powder body.

[0090] It should be understood that the modified mineral powder includes the mineral powder modifier provided in this embodiment, and thus has at least all the characteristics and advantages of the mineral powder modifier, which will not be described in detail here.

[0091] In this embodiment, when the mineral powder modifier is applied to the mineral powder to improve the activity of the mineral powder, the addition amount of the mineral powder modifier is 1% to 5% of the mass of the mineral powder body, for example, 1%, 2%, 3%, 4%, 5%, etc. When the mineral powder modifier is added to the mineral powder, its addition amount should not be too high or too low. If the addition amount is too low, it is not enough to effectively activate the mineral powder. If the content is too high, it may have an adverse effect on the processability of the mineral powder.

[0092] Compared with the existing mineral powder modifiers, the mineral powder modifier of this embodiment composed of modified nano calcium hydroxide, silicon dioxide and inorganic salt promoting composition is also very effective at low dosages, that is, it can effectively stimulate the activity of mineral powder at low dosages, which can save costs.

[0093] The following further describes the mineral powder modifier and its preparation method of the present application with specific examples. Those skilled in the art will understand that the description in the present invention is only part of the examples, and any other suitable specific examples are within the scope of the present invention.

[0094] Example 1

[0095] 1. A mineral powder modifier, comprising the following components in parts by weight:

[0096] 85 parts of modified nano calcium hydroxide, 10 parts of inorganic salt promoting composition and 5 parts of silicon dioxide.

[0097] The inorganic salt promoting composition includes disodium hydrogen phosphate and calcium nitrate in a mass ratio of 9:1.

[0098] 2. A method for preparing a mineral powder modifier, comprising the following steps:

[0099] (1) Preparation of modified nano calcium hydroxide: add 14 g of a water reducing agent such as PCE to 100 g of water, stir and disperse at a low speed for 15 min to form a base solution, and add an organic base dropwise to adjust the pH value of the base solution to 12.5 to obtain a dispersed base solution;

[0100] The prepared 200 g / L calcium nitrate solution and sodium hydroxide solution were added dropwise in a molar ratio of 1:1 (the total time of the addition was 30 min) into the dispersed base liquid. After 30 s of the addition, high-speed stirring was started at a stirring rate of 1500 rpm. After the addition was completed, the reaction was continued for 2 h to obtain a light blue calcium hydroxide-water reducer suspension; the calcium hydroxide-water reducer suspension was then freeze-dried to obtain a powder to obtain powdered modified nano calcium hydroxide.

[0101] (2) Preparation of mineral powder modifier: After adding 9 g of disodium hydrogen phosphate, 1 g of calcium nitrate, 85 g of modified nano calcium hydroxide powder and 5 g of silicon dioxide into a mixing kettle, the reactor was closed, the vent valve was opened, nitrogen was filled into the mixing kettle, stirring was started, and after mixing for 30 minutes, stirring was turned off to obtain a mineral powder modifier.

[0102] Example 2

[0103] 1. A mineral powder modifier, comprising the following components in parts by weight:

[0104] 80 parts of modified nano calcium hydroxide, 11 parts of inorganic salt promoting composition and 9 parts of silicon dioxide.

[0105] The inorganic salt promoting composition includes disodium hydrogen phosphate and calcium formate in a mass ratio of 9:2.

[0106] 2. A method for preparing a mineral powder modifier, comprising the following steps:

[0107] (1) Preparation of modified nano calcium hydroxide: add 10 g of a water reducing agent such as PCE to 100 g of water, stir and disperse at a low speed for 15 min to form a base solution, and add an organic base dropwise to adjust the pH value of the base solution to 13.0 to obtain a dispersed base solution;

[0108] The prepared 100 g / L calcium nitrate solution and sodium hydroxide solution were added dropwise into the dispersed base liquid at a molar ratio of 1:1 (the total adding time was 30 min), and the stirring rate was 2500 rpm. After the adding was completed, the reaction was continued for 2 h to obtain a light blue calcium hydroxide-water reducer suspension; the calcium hydroxide-water reducer suspension was then freeze-dried to obtain a powder to obtain powdered modified nano calcium hydroxide.

[0109] (2) Preparation of mineral powder modifier: After adding 9 g of disodium hydrogen phosphate, 2 g of calcium formate, 80 g of modified nano calcium hydroxide powder and 9 g of silicon dioxide into a mixing kettle, the reactor was closed, the vent valve was opened, nitrogen was filled into the mixing kettle, stirring was started, and after mixing for 30 minutes, stirring was turned off to obtain a mineral powder modifier.

[0110] Example 3

[0111] 1. A mineral powder modifier, comprising the following components in parts by weight:

[0112] 70 parts of modified nano calcium hydroxide, 20 parts of inorganic salt promoting composition and 10 parts of silicon dioxide.

[0113] The inorganic salt promoting composition includes disodium hydrogen phosphate and calcium acetate in a mass ratio of 10:10.

[0114] 2. A method for preparing a mineral powder modifier, comprising the following steps:

[0115] (1) Preparation of modified nano calcium hydroxide: add 20 g of a water reducing agent such as PCE to 100 g of water, stir and disperse at a low speed for 15 min to form a base liquid, and adjust the pH value of the base liquid to 13.0 to obtain a dispersed base liquid;

[0116] The prepared 300 g / L calcium nitrate solution and sodium hydroxide solution were added dropwise in a molar ratio of 1:1 (the total adding time was 30 min) into the dispersed base liquid at a stirring rate of 3000 rpm. After the adding was completed, the reaction was continued for 2 h to obtain a light blue calcium hydroxide-water reducer suspension; the calcium hydroxide-water reducer suspension was then vacuum dried at 60°C to obtain a powder to obtain powdered modified nano calcium hydroxide.

[0117] (2) Preparation of mineral powder modifier: After adding 10 g of disodium hydrogen phosphate, 10 g of calcium acetate, 70 g of modified nano calcium hydroxide powder and 10 g of silicon dioxide into a mixing kettle, the reactor was closed, the vent valve was opened, nitrogen was filled into the mixing kettle, stirring was started, and after mixing for 30 minutes, stirring was turned off to obtain a mineral powder modifier.

[0118] Example 4

[0119] 1. A mineral powder modifier, comprising the following components in parts by weight:

[0120] 82 parts of modified nano calcium hydroxide, 13 parts of inorganic salt promoting composition and 5 parts of silicon dioxide.

[0121] The inorganic salt promoting composition includes sodium hexametaphosphate and calcium salt in a mass ratio of 10:3, and the calcium salt includes calcium nitrate and calcium formate in a mass ratio of 1:1.

[0122] 2. A method for preparing a mineral powder modifier, comprising the following steps:

[0123] (1) Preparation of modified nano calcium hydroxide: add 10 g of a water reducing agent such as PCE to 100 g of water, stir and disperse at a low speed for 15 min to form a base solution, and add an organic base dropwise to adjust the pH value of the base solution to 13.0 to obtain a dispersed base solution;

[0124] The prepared 100 g / L calcium nitrate solution and sodium hydroxide solution were added dropwise into the dispersed base liquid at a molar ratio of 1:1 (the total adding time was 30 min), and the stirring rate was 2000 rpm. After the adding was completed, the reaction was continued for 2 h to obtain a light blue calcium hydroxide-water reducer suspension; the calcium hydroxide-water reducer suspension was then freeze-dried to obtain a powder to obtain powdered modified nano calcium hydroxide.

[0125] (2) Preparation of mineral powder modifier: After adding 10 g of sodium hexametaphosphate, 3 g of calcium salt (calcium nitrate: calcium formate = 1:1), 82 g of modified nano calcium hydroxide powder and 5 g of silicon dioxide into a V-shaped mixing kettle, the reactor was closed, the vent valve was opened, nitrogen was filled into the mixing kettle, stirring was started, and after mixing for 30 minutes, stirring was turned off to obtain a mineral powder modifier.

[0126] Comparative Example 1

[0127] A mineral powder modifier comprises the following components in parts by weight:

[0128] Commercially available calcium hydroxide (D 50 =5μm) 85 parts, an inorganic salt promoting composition 10 parts and silicon dioxide 5 parts.

[0129] The rest are the same as in Example 1.

[0130] The main difference between Comparative Example 1 and Example 1 is that commercially available calcium hydroxide (D 50 =5μm) to replace the modified nano calcium hydroxide powder.

[0131] Comparative Example 2

[0132] A mineral powder modifier comprises the following components in parts by weight:

[0133] 85 parts of modified nano calcium hydroxide, 10 parts of inorganic salt promoter and 5 parts of silicon dioxide;

[0134] Among them, the inorganic salt promoter is calcium fluoride.

[0135] The rest are the same as in Example 1.

[0136] The main difference between Comparative Example 2 and Example 1 is that calcium fluoride is used to replace the inorganic salt promoting composition.

[0137] Performance Testing

[0138] In the present invention, performance tests were performed on the mineral powder modifiers of Examples 1 to 4 and the mineral powder modifiers of Comparative Examples 1 to 2.

[0139] The test methods include: Quarterly test method for cement mortar strength in accordance with GB / T 17671-2021.

[0140] The test mortar mix is ​​shown in Table 1 below. There is no modifier in the base mortar. The modifier dosage and performance test results of the test group are shown in Table 2 below.

[0141] Table 1 Mortar base ratio

[0142] Types of mortar Mineral powder / g ISO standard sand / g Water / g Test mortar 450 1350 225

[0143] Table 2 Modification test results

[0144]

[0145]

[0146] It can be seen from the test data in Table 2 that the mineral powder modifier provided in Examples 1 to 4 of the present invention can quickly stimulate the mineral powder vitreous structure through the homemade modified nano calcium hydroxide particles, improve the gelling activity and volcanic ash activity of the mineral powder, and thus improve the early activity of the mineral powder. Therefore, compared with Comparative Example 1 in which no modified nano calcium hydroxide particles are added, the examples of the present invention improve the activity of the mineral powder by adding the homemade modified nano calcium hydroxide particles, thereby significantly improving the early compressive strength of the mineral powder.

[0147] At the same time, through the analysis and comparison of Example 1 and Comparative Example 2, it can be seen that after adding the inorganic salt promoting composition provided by the embodiment of the present invention into the formula, the prepared modifier can also promote the mid- and late-stage activity of the mineral powder, so that the mineral powder mortar with the mineral powder modifier of the embodiment of the present invention added obtains a very high compressive strength and has excellent mechanical properties.

[0148] Parts of the present invention that are not described in detail are well known to those skilled in the art.

[0149] It should be noted that the term "and / or" or " / " used in this document is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The singular forms of "a", "the" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0150] In the detailed description and claims, a list of items connected by the terms "at least one of," "at least one of," "at least one of," or other similar terms may mean any combination of the listed items. For example, if items A, B are listed, the phrase "at least one of A, B" means only A; only B; or A and B. In another example, if items A, B, C are listed, the phrase "at least one of A, B, C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may include a single element or multiple elements. Item B may include a single element or multiple elements. Item C may include a single element or multiple elements.

[0151] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A mineral powder modifier, characterized in that: The mineral powder modifier comprises the following components in parts by weight: 70-90 parts of modified nano calcium hydroxide, 10-40 parts of inorganic salt promoting composition and 0-10 parts of silicon dioxide; Wherein, the modified nano calcium hydroxide is nano calcium hydroxide surface-modified with a water reducing agent; The water reducer includes a polycarboxylate water reducer or a modified polycarboxylate water reducer; and / or, the inorganic salt promoting composition comprises a combination of phosphate and calcium salt; The preparation method of the modified nano calcium hydroxide comprises: Adding a water reducing agent to water, stirring and dispersing to form a base liquid, and adjusting the pH value of the base liquid to obtain a dispersed base liquid; Under stirring conditions, adding a calcium compound solution and a hydroxide solution to the dispersed base liquid to obtain a calcium hydroxide-water reducing agent suspension; The calcium hydroxide-water reducing agent suspension is dried to obtain the modified nano calcium hydroxide in powder form.

2. The mineral powder modifier according to claim 1, characterized in that: The mineral powder modifier comprises the following components in parts by weight: 75-85 parts of modified nano calcium hydroxide, 10-30 parts of inorganic salt promoting composition and 2-10 parts of silicon dioxide.

3. The mineral powder modifier according to claim 1, characterized in that: The mass ratio of the phosphate to the calcium salt is 9:1 to 5:

5.

4. The mineral powder modifier according to claim 1, characterized in that: The phosphate includes at least one of sodium hexametaphosphate, disodium hydrogen phosphate or sodium polyphosphate; And / or, the calcium salt includes at least one of calcium nitrate, calcium acetate or calcium formate.

5. The mineral powder modifier according to any one of claims 1 to 4, characterized in that: The average particle size of the modified nano calcium hydroxide is ≤100nm; And / or, the silicon dioxide is a silicon dioxide with a porous structure, the diameter distribution of the pores in the silicon dioxide with a porous structure is 0.5nm to 15nm, and the saturated water absorption capacity of the silicon dioxide with a porous structure is ≥50%.

6. The mineral powder modifier according to claim 1, characterized in that: In the preparation method of modified nano calcium hydroxide, the pH value of the base liquid is 12.5-13; And / or, the stirring rate of the stirring condition is 1300-4000 rpm, and the stirring is performed under a nitrogen atmosphere; and / or, the concentration of the calcium-containing compound in the calcium-containing compound solution is 10 to 300 g / L; And / or, the amount of the water reducing agent is 1% to 20% of the mass of the calcium-containing compound in the calcium-containing compound solution.

7. A method for preparing a mineral powder modifier, characterized in that: The mineral powder modifier comprises the mineral powder modifier according to any one of claims 1 to 6, and the method comprises: The modified nano calcium hydroxide, the inorganic salt promoting composition and silicon dioxide in the formulated amount are uniformly mixed to obtain the mineral powder modifier.

8. The method for preparing the mineral powder modifier according to claim 7, characterized in that: The uniform mixing is carried out in an atmosphere without carbon dioxide.

9. A modified mineral powder, comprising a mineral powder body, characterized in that: Also includes the mineral powder modifier according to any one of claims 1 to 6 or the mineral powder modifier prepared by the preparation method according to any one of claims 7 to 8; Wherein, the added amount of the mineral powder modifier is 1% to 5% of the mass of the mineral powder body.

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