A cement strength enhancer and its preparation method and application

Abstract

The invention discloses a cement strength enhancer. The method comprises the following steps: drying and grinding lithium slag, and mixing the mixture with an aqueous solution of a polyolamine compound A having a concentration of 2-4 wt% to obtain treated lithium slag; adding a silane coupling agent to an aqueous solution of a dibasic organic acid under stirring conditions and hydrolyzing the mixture for 10-15 minutes to obtain a silane coupling agent treatment liquid; sequentially adding the obtained silane coupling agent treatment liquid and the remaining dibasic organic acid compound to the obtained lithium slag, stirring the mixture at room temperature, and vacuum drying the mixture to obtain a mixture; sequentially adding a polyolamine compound B and an inorganic salt compound to the obtained mixture, and then mixing the mixture in a mixer for 30-60 minutes to obtain the cement strength enhancer. The method uses lithium slag as a carrier, fills the polyolamine therein, and coats the surface of the polyolamine with the silane coupling agent and the dibasic organic acid, thereby effectively solving the problem of polyolamine being consumed in the early stage of cement hydration. The polyolamine gradually reacts and releases reinforcing substances under the alkaline conditions provided by cement hydration, thereby matching the reinforcing effect of the entire cement hydration process.

Description

Technical Field

[0001] The present invention belongs to the technical field of materials, and in particular relates to a cement strength enhancer and a preparation method and application thereof. Background Art

[0002] Cement is a fundamental raw material for civil construction, and the cement industry is inextricably linked to economic development. Improving cement strength and reducing clinker usage during cement production can effectively lower production costs, reduce energy consumption, and reduce carbon emissions.

[0003] Currently, cement production uses cement grinding aids primarily containing alcoholamines. These active ingredients promote cement hydration and increase strength, thereby reducing cement clinker usage while maintaining strength. Extensive research has demonstrated that the mechanism by which alcoholamines promote cement hydration is by complexing ions produced during cement hydration, thereby promoting the dissolution of cement minerals and accelerating cement hydration. However, cement hydration is very rapid in the early stages after water addition. The alcoholamines that form complexes with cement hydration ions are easily "buried" and consumed by the resulting hydration products, fundamentally contributing to the limited cement-strengthening effect of alcoholamines. Furthermore, the cement production process incorporates admixtures such as slag, fly ash, and pozzolanic materials. These admixtures require the alkaline conditions generated by cement hydration to activate, often requiring activation after 7 or even 28 days. Consequently, due to the significant consumption of alcoholamines during early cement hydration, effective activation of admixture activity is not achieved in the later stages of cement hydration.

[0004] CN111995265 provides an early-strength powdered slag grinding aid and its preparation method. The grinding aid is made from the following raw materials by weight: 40-60 parts of desulfurization and denitrification ash, 3-8 parts of triethanolamine, 1-5 parts of triisopropanolamine, 15-25 parts of fly ash, and 3-10 parts of gypsum. The preparation method of the grinding aid comprises the following steps: a. weighing all raw materials according to the formula, adding organic reagents such as triethanolamine and triisopropanolamine to a certain amount of anhydrous ethanol, and stirring at 700 rpm on a magnetic stirrer for 10-30 minutes to uniformly dissolve; b. adding powdered materials such as desulfurization and denitrification ash, gypsum, and fly ash, and continuing stirring for 5-10 minutes to prepare a mixed solution; and c. placing the mixed solution in a vacuum drying apparatus and drying it for 3-6 hours to prepare an early-strength powdered slag grinding aid with a core-shell structure. The organic reagent of the invention is adsorbed on the surface of the inorganic powder material to form a core-shell structure. It is inevitable that the organic reagent adsorbed on the surface of the inorganic powder material is adsorbed on the surface of the cement hydration product and is consumed and rendered ineffective.

[0005] CN113185183 discloses a cement mineralizer and its preparation method, relating to the field of cement preparation technology. The cement mineralizer comprises the following components, by weight: 15-25 parts triethanolamine, 10-15 parts diethanol monoisoolamine, 5-15 parts triisopropanolamine, 2-5 parts adjuvant, 2-5 parts stabilizer, 1-3 parts lignin calcium sulfate, 1-3 parts molasses, 2-5 parts urea, 5-20 parts water, and 60-80 parts industrial waste residue. The preparation method comprises the following steps: weighing corresponding parts by weight of the raw materials; mixing the triethanolamine, diethanol monoisoolamine, triisopropanolamine, adjuvant, stabilizer, lignin calcium sulfate, molasses, urea, a polyol, and water; and stirring to obtain a mixture; adding the industrial waste residue and limestone powder to the mixture, stirring to obtain a mixture, and allowing it to stand for 2-3 days to obtain a finished product. This preparation method involves simple material mixing, without significant interaction between the different components, and has limited effect on improving cement strength.

[0006] CN116217114 relates to a powder-liquid composite slag grinding aid, its preparation method, and application, and relates to the technical field of slag grinding aids. The powder-liquid composite slag grinding aid comprises a powder slag grinding aid and a liquid slag grinding aid. The powder slag grinding aid comprises: 5-10 parts of an alcohol amine, 3-8 parts of a polyol, 10-20 parts of a polycarboxylic acid water reducer, 5-10 parts of calcium lignin sulfonate, 30-50 parts of SDS desulfurization waste residue, and 10-15 parts of water; the liquid slag grinding aid comprises: 10-20 parts of an alcohol amine, 8-15 parts of a polyol, 15-20 parts of a polycarboxylic acid water reducer, 3-5 parts of calcium lignin sulfonate, 20-25 parts of SDS desulfurization waste residue, and 25-35 parts of water. The preparation method of this invention involves simple material mixing, without significant interaction between the different components, resulting in limited improvement in cement strength.

[0007] CN110255954 provides a nano-lithium slag early strength agent, its preparation method, and application. The nano-lithium slag early strength agent is prepared by wet grinding the following components, calculated by weight: lithium slag: 20-35 parts, ionic solubilizer: 0.5-2 parts, surface modifier: 0.1-0.5 parts, fluidization stabilizer: 0.1-0.5 parts, and the balance is water; the total of the lithium slag, ionic solubilizer, surface modifier, fluidization stabilizer, and water is 100 parts. This invention primarily improves the fineness of the lithium slag and increases the specific surface area of the lithium slag to provide crystal nucleation growth points for cement hydration products, thereby promoting the dissolution of lithium, calcium, aluminum, and silicon ions in the lithium slag. The dissolved ions can further promote early hydration of cement. However, the activation of lithium slag activity requires alkaline conditions generated by cement hydration. Cement hydration rates are high in the early stages, making it difficult for lithium slag to achieve effective reinforcement. Furthermore, nanoscale lithium slag is already fully activated early on, making it difficult to effectively enhance cement strength in the later stages. Furthermore, the invention's mechanical grinding of lithium slag to nanoscale is challenging. The dosage of the nanolithium slag early strength agent provided by the invention is relatively high, at 0.5% to 4.0% of the cement dosage. Summary of the Invention

[0008] The present invention aims to provide a cement strength enhancer and a preparation method and application thereof. The characteristics of industrial solid waste are fully utilized, lithium slag is used as a carrier, polyol amine is filled therein, and a silane coupling agent and a dibasic organic acid are coated on the surface. The problem of polyol amine being consumed in the early hydration of cement is effectively solved. Under the alkaline conditions provided by cement hydration, the enhancing substances are gradually reacted and released, matching the whole process enhancement effect of cement hydration. In addition, different components act synergistically with each other, thereby improving cement strength from multiple angles and having a significant enhancement effect on the strength of cement at all ages.

[0009] In order to achieve the above purpose, the technical solutions adopted are as follows:

[0010] A cement strength enhancer is prepared according to the following method:

[0011] (1) Dry the lithium slag to a moisture content of <1wt% and grind it to a specific surface area of 300~400m 2 / kg;

[0012] (2) mixing with an aqueous solution of a polyol amine compound A having a concentration of 2 to 4 wt% to obtain treated lithium slag;

[0013] (3) preparing a portion of the dibasic organic acid compound into an aqueous solution with a pH value of 3 to 5, adding a silane coupling agent thereto and hydrolyzing for 10 to 15 minutes under stirring to obtain a silane coupling agent treatment solution;

[0014] (4) adding the silane coupling agent treatment solution obtained in step (3) and the remaining dibasic organic acid compound to the lithium slag obtained in step (2) in sequence, stirring at room temperature for 6 to 8 hours, and vacuum drying at 40 to 45° C. until the moisture is completely removed to obtain a mixture;

[0015] (5) Adding the polyol amine compound B and the inorganic salt compound to the mixture obtained in step (4) in sequence, and then placing the mixture in a mixer and mixing for 30 to 60 minutes to obtain the cement strength enhancer.

[0016] According to the above scheme, the mass percentages of the raw materials used are as follows:

[0017] 70~90 parts of lithium slag,

[0018] 2 to 3 parts of polyol amine compound A,

[0019] 4 to 8 parts of silane coupling agent,

[0020] 0.5 to 2 parts of dibasic organic acid compound,

[0021] 4 to 6 parts of polyol amine compound B,

[0022] 10 to 20 parts of inorganic salt compound.

[0023] According to the above scheme, the lithium slag is the waste slag produced by extracting lithium from lithium ore, with SiO2 content > 50wt%, CaO content > 10wt%, Al2O3 content > 15wt%, and SO3 content > 5wt%.

[0024] According to the above scheme, the polyol amine compound A is one of triethanolamine, diethanol monoisopropanolamine, hydroxyethyl diisopropanolamine, triisopropanolamine, tetrahydroxyethyl ethylenediamine or any mixture thereof.

[0025] According to the above scheme, the silane coupling agent is KH-570.

[0026] According to the above scheme, the dibasic organic acid compound is one of oxalic acid, malonic acid, maleic acid, and fumaric acid, or any mixture thereof.

[0027] According to the above scheme, the polyol amine compound B is one of triethanolamine, diethanol monoisopropanolamine, hydroxyethyl diisopropanolamine, triisopropanolamine, tetrahydroxyethyl ethylenediamine or any mixture thereof.

[0028] According to the above scheme, the inorganic salt compound is one of sodium sulfate, sodium thiosulfate, sodium pyrosulfate, sodium thiocyanate, and lithium carbonate, or any mixture thereof.

[0029] The preparation method of the above-mentioned cement strength enhancer comprises the following steps:

[0030] (1) Dry the lithium slag to a moisture content of <1wt% and grind it to a specific surface area of 300~400m 2 / kg;

[0031] (2) mixing with an aqueous solution of a polyol amine compound A having a concentration of 2 to 4 wt% to obtain treated lithium slag;

[0032] (3) preparing a portion of the dibasic organic acid compound into an aqueous solution with a pH value of 3 to 5, adding a silane coupling agent thereto and hydrolyzing for 10 to 15 minutes under stirring to obtain a silane coupling agent treatment solution;

[0033] (4) adding the silane coupling agent treatment solution obtained in step (3) and the remaining dibasic organic acid compound to the lithium slag obtained in step (2) in sequence, stirring at room temperature for 6 to 8 hours, and vacuum drying at 40 to 45° C. until the moisture is completely removed to obtain a mixture;

[0034] (5) Adding the polyol amine compound B and the inorganic salt compound to the mixture obtained in step (4) in sequence, and then placing the mixture in a mixer and mixing for 30 to 60 minutes to obtain the cement strength enhancer.

[0035] The application of the above-mentioned cement strength enhancer in cement, wherein the dosage of the cement strength enhancer is 0.3-0.5wt% of the cement mass.

[0036] The lithium slag in the present invention is an industrial waste slag with potential volcanic ash activity. It can dissociate under the alkaline conditions generated by cement hydration to form minerals that are the same as the cement hydration products but smaller in size, which fill the pores of the cement hydration products, making the cement stone structure denser, thereby greatly improving the cement strength, especially the later strength. Lithium ions are metal cations with the smallest radius. During the cement hydration process, they can be replaced with other metal ions, thereby promoting cement hydration and improving cement strength. Gypsum in lithium slag can promote the formation of calcium aluminate during cement hydration, thereby improving cement strength. Lithium slag has a porous structure, which can effectively allow polyol amines to be adsorbed and retained in the pore structure. Grinding the lithium slag can break the chemical bonds in the lithium slag minerals, thereby increasing the adsorption sites for polyol amines. The specific surface area of the lithium slag after grinding is controlled to be 300~400m 2 / kg, on the one hand, in order to maintain the same specific surface area range as that of common cement, so as not to have an adverse effect on other properties of cement except strength; on the other hand, a larger specific surface area is conducive to enhancing the volcanic ash activity of the lithium slag itself and is conducive to the adsorption of polyol amines. The control of a certain upper limit of the specific surface area is to prevent the porous structure of the lithium slag from being destroyed as much as possible.

[0037] The polyolamine compound A used in the present invention is a good cement strengthener. It can be evenly dispersed in the porous structure of lithium slag under ultrasonic conditions. The polyolamine compound A is alkaline and can "erode" the pores of the lithium slag, allowing it to be retained in large quantities within the pores. The polyolamine compound A retained in the pores of the lithium slag effectively avoids being consumed by adsorption on the surface of the cement hydration product during the early stages of cement hydration. Furthermore, the alkaline conditions generated by cement hydration gradually dissociate the lithium slag and are then slowly released, thereby achieving overall cement strength enhancement throughout the hydration process, particularly enhancing cement strength in the later stages.

[0038] The silane coupling agent used in the present invention can be better hydrolyzed in a dibasic organic acid aqueous solution with a pH value of 3 to 5, and silanol is generated after hydrolysis. The hydrolyzed silane coupling agent can form a covalent bond with a large number of silicon-oxygen bonds on the surface of the lithium slag after grinding, and a reactive coating film is formed on the surface of the lithium slag filled with polyol amine compound A in the pores, further protecting the polyol amine compound A filled in the lithium slag pores from being released and consumed in the early stage of cement hydration. The silane coupling agent KH-570 is selected on the one hand because it has a better modification effect on minerals whose main component is SiO2; on the other hand, it can be hydrolyzed under the alkaline conditions generated by cement hydration, thereby exposing the lithium slag to better dissociate. Silane itself is also a substance that can effectively improve the density of cement hydration products, and it has a certain strengthening effect on cement.

[0039] The dibasic organic acid compound used in the present invention can provide acidic conditions for the hydrolysis of the silane coupling agent. At the same time, the dibasic organic acid can coordinate with calcium to form a stable complex. The dibasic organic acid can be adsorbed on the surface of the lithium slag to supplement the coating film of the silane coupling agent, further improving the stability of the coating film.

[0040] The polyol amine compound B used in the present invention can promote cement hydration through complexation, thereby improving cement strength.

[0041] The inorganic salt compound used in the present invention can effectively promote the early hydration of cement and improve the early strength of cement by ion exchange and acting as an electrolyte.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] 1. The raw materials of the cement strength enhancer provided by the present invention are easily available, the preparation method is simple, and it can be industrialized. It also fully utilizes the characteristics of industrial solid waste and can achieve high-value utilization of industrial solid waste;

[0044] 2. The cement strength enhancer provided by the present invention uses lithium slag as a carrier, polyol amine is filled therein, and a silane coupling agent and a dibasic organic acid are coated on the surface. This can effectively solve the problem of polyol amine being consumed during the early hydration of cement.

[0045] 3. The cement strength enhancer provided by the present invention can gradually react and release strengthening substances under the alkaline conditions provided by cement hydration, achieving a strengthening effect that matches the entire process of cement hydration;

[0046] 4. The cement strength enhancer provided by the present invention has each component having an effect of improving cement strength, and different components act synergistically with each other to improve cement strength from multiple angles, with a significant strengthening effect. DETAILED DESCRIPTION

[0047] The following examples further illustrate the technical solutions of the present invention, but are not intended to limit the scope of protection of the present invention. The following specific examples are only some preferred embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, modifications, substitutions, and improvements made by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0048] The specific embodiment provides a method for preparing a cement strength enhancer, comprising the following steps:

[0049] (1) Dry the lithium slag at 40-45°C until the moisture is less than 1wt% and then grind it to a specific surface area of 300-400m 2 / kg;

[0050] (2) taking a certain mass of the lithium slag prepared in step (1), adding 2-4 wt% of an aqueous solution of a polyol amine compound A in proportion, and then ultrasonically dispersing for 10-15 minutes to obtain treated lithium slag;

[0051] (3) A certain amount of dibasic organic acid compound is prepared into an aqueous solution with a pH value of 3 to 5, and a silane coupling agent is added thereto for hydrolysis for 10 to 15 minutes under stirring conditions of 400 to 600 r / min to obtain a silane coupling agent treatment solution;

[0052] (4) adding the silane coupling agent treatment solution obtained in step (3) and the remaining dibasic organic acid compound to the treated lithium slag prepared in step (2) in sequence, stirring the mixture at room temperature at 600-800 r / min for 6-8 hours, and then vacuum drying the mixture at 40-45° C. until the moisture is completely removed to obtain a mixture;

[0053] (5) Adding the polyol amine compound B and the inorganic salt compound to the mixture prepared in step (4) in proportion, and then placing the mixture in a mixer and mixing it at 40-60 r / min for 30-60 min to obtain the cement strength enhancer.

[0054] Specifically, the raw materials used are as follows by mass:

[0055] 70~90 parts of lithium slag,

[0056] 2 to 3 parts of polyol amine compound A,

[0057] 4 to 8 parts of silane coupling agent,

[0058] 0.5 to 2 parts of dibasic organic acid compound,

[0059] 4 to 6 parts of polyol amine compound B,

[0060] 10 to 20 parts of inorganic salt compound.

[0061] Specifically, the lithium slag is waste residue produced by extracting lithium from lithium ore, with SiO2 content of 53.69wt%, CaO content of 10.22wt%, Al2O3 content of 19.23wt%, SO3 content of 7.02wt%, moisture content of less than 1wt% after treatment, and specific surface area of 300~400m 2 / kg.

[0062] Specifically, the polyol amine compound A is one of triethanolamine, diethanol monoisopropanolamine, hydroxyethyl diisopropanolamine, triisopropanolamine, and tetrahydroxyethyl ethylenediamine, or any mixture thereof.

[0063] Specifically, the silane coupling agent is silane coupling agent KH-570, which is commercially available from Shanghai Yuanye Biotechnology Co., Ltd.

[0064] Specifically, the organic acid compound is one of oxalic acid, malonic acid, maleic acid, and fumaric acid, or any mixture thereof.

[0065] Specifically, the polyol amine compound B is one of triethanolamine, diethanol monoisopropanolamine, hydroxyethyl diisopropanolamine, triisopropanolamine, and tetrahydroxyethyl ethylenediamine, or any mixture thereof.

[0066] Specifically, the inorganic salt compound is one of sodium sulfate, sodium thiosulfate, sodium pyrosulfate, sodium thiocyanate, and lithium carbonate, or any mixture thereof.

[0067] Specifically, KH-570 was commercially available from Shanghai Yuanye Biotechnology Co., Ltd. The remaining raw materials were commercially available unless otherwise specified.

[0068] The specific embodiment also provides the use of the above-mentioned cement strength enhancer in cement, wherein the dosage of the cement strength enhancer is 0.3-0.5 wt% of the cement mass.

[0069] Example 1

[0070] (1) The lithium slag was dried at 40°C to a moisture content of 0.1 wt% and then ground to a specific surface area of 300.0 m 2 / kg;

[0071] (2) 70 g of the lithium slag prepared in step (1) was added with 100 g of a 2 wt% aqueous solution of triethanolamine, followed by ultrasonic dispersion for 10 min to obtain treated lithium slag;

[0072] (3) 0.1 g of oxalic acid was prepared into an aqueous solution with a pH value of 3.0, 4.0 g of silane coupling agent KH-570 was added thereto under stirring conditions of 400 r / min and hydrolyzed for 10 min to obtain a silane coupling agent treatment solution;

[0073] (4) adding the silane coupling agent treatment solution obtained in step (3) and 0.4 g of oxalic acid to the treated lithium slag prepared in step (2) in sequence, stirring the mixture under magnetic stirring at 600 r / min for 6.0 h at room temperature, and then vacuum drying the mixture at 40° C. until the moisture is completely removed to obtain a mixture;

[0074] (5) To the mixture prepared in step (4), 4.0 g of tetrahydroxyethylethylenediamine and 10.0 g of sodium sulfate were added in sequence, and then placed in a mixer and mixed at 40 r / min for 30 min to obtain the cement strength enhancer.

[0075] Example 2

[0076] (1) The lithium slag was dried at 45°C to a moisture content of 0.9 wt% and then ground to a specific surface area of 400.0 m 2 / kg;

[0077] (2) taking 90 g of the lithium slag prepared in step (1), adding 75 g of a 4 wt % aqueous solution of diethanol monoisopropanolamine, and then ultrasonically dispersing for 15 min to obtain treated lithium slag;

[0078] (3) 1.8 g of malonic acid was prepared into an aqueous solution with a pH value of 5.0, 8.0 g of silane coupling agent KH-570 was added thereto under stirring conditions of 600 r / min and hydrolyzed for 15 min to obtain a silane coupling agent treatment solution;

[0079] (4) adding the silane coupling agent treatment solution obtained in step (3) and 0.2 g of malonic acid to the treated lithium slag prepared in step (2) in sequence, stirring the mixture with a magnetic stirrer at 800 rpm for 8.0 h at room temperature, and then vacuum drying the mixture at 45° C. until the moisture is completely removed to obtain a mixture;

[0080] (5) To the mixture prepared in step (4), 6.0 g of triisopropanolamine and 20.0 g of sodium thiosulfate were added in sequence, and then placed in a mixer and mixed at 60 r / min for 60 min to obtain the cement strength enhancer.

[0081] Example 3

[0082] (1) The lithium slag was dried at 41°C to a moisture content of 0.1 wt% and then ground to a specific surface area of 333.8 m 2 / kg;

[0083] (2) taking 71 g of the lithium slag prepared in step (1), adding 75 g of a 2.8 wt% aqueous solution of hydroxyethyl diisopropanolamine, and then ultrasonically dispersing for 11 minutes to obtain treated lithium slag;

[0084] (3) 0.3 g of maleic acid was prepared into an aqueous solution with a pH value of 3.3, 6.0 g of silane coupling agent KH-570 was added thereto under stirring conditions of 500 r / min and hydrolyzed for 13 min to obtain a silane coupling agent treatment solution;

[0085] (4) adding the silane coupling agent treatment solution obtained in step (3) and 0.5 g of maleic acid to the treated lithium slag prepared in step (2) in sequence, stirring with a magnetic force of 712 r / min at room temperature for 6.3 h, and then vacuum drying at 41° C. until the moisture is completely removed to obtain a mixture;

[0086] (5) To the mixture prepared in step (4), 4.1 g of hydroxyethyl diisopropanolamine and 11.5 g of sodium pyrosulfate were added in sequence, and then placed in a mixer and mixed at 45 r / min for 32 min to obtain the cement strength enhancer.

[0087] Example 4

[0088] (1) The lithium slag was dried at 43°C to a moisture content of 0.8 wt% and then ground to a specific surface area of 367.1 m 2 / kg;

[0089] (2) 78 g of the lithium slag prepared in step (1) was added with 69.23 g of a 3.9 wt % aqueous solution of triisopropanolamine, followed by ultrasonic dispersion for 13 min to obtain treated lithium slag;

[0090] (3) 1.0 g of fumaric acid was prepared into an aqueous solution with a pH value of 4.5, 4.1 g of silane coupling agent KH-570 was added thereto under stirring conditions of 467 r / min and hydrolyzed for 12 min to obtain a silane coupling agent treatment solution;

[0091] (4) adding the silane coupling agent treatment solution obtained in step (3) and 0.3 g of fumaric acid to the treated lithium slag prepared in step (2) in sequence, stirring with a magnetic force of 689 rpm at room temperature for 7.6 h, and then vacuum drying at 42° C. until the moisture is completely removed to obtain a mixture;

[0092] (5) 5.3 g of diethanol monoisopropanolamine and 12.3 g of sodium thiocyanate were added to the mixture prepared in step (4) in sequence, and then placed in a mixer and mixed at 41 r / min for 58 min to obtain the cement strength enhancer.

[0093] Example 5

[0094] (1) The lithium slag was dried at 42°C to a moisture content of 0.5 wt% and then ground to a specific surface area of 387.2 m 2 / kg;

[0095] (2) 89 g of the lithium slag prepared in step (1) was added with 83.33 g of a 3.0 wt% aqueous solution of tetrahydroxyethylethylenediamine, followed by ultrasonic dispersion for 14 min to obtain treated lithium slag;

[0096] (3) 0.2 g of maleic anhydride was prepared into an aqueous solution with a pH value of 4.0, 5.9 g of silane coupling agent KH-570 was added thereto under stirring conditions of 412 r / min and hydrolyzed for 11 min to obtain a silane coupling agent treatment solution;

[0097] (4) adding the silane coupling agent treatment solution obtained in step (3) and 0.4 g of maleic anhydride to the treated lithium slag prepared in step (2) in sequence, stirring with a magnetic force of 652 r / min at room temperature for 7.9 h, and then vacuum drying at 45° C. until the moisture is completely removed to obtain a mixture;

[0098] (5) To the mixture prepared in step (4), 5.0 g of triethanolamine and 16.7 g of lithium carbonate were added in sequence, and then placed in a mixer and mixed at 59 rpm for 45 min to obtain the cement strength enhancer.

[0099] Example 6

[0100] (1) The lithium slag was dried at 44°C to a moisture content of 0.3 wt% and then ground to a specific surface area of 312.5 m 2 / kg;

[0101] (2) 85 g of the lithium slag prepared in step (1) was added with 96.00 g of a 2.5 wt% aqueous solution of diethanol monoisopropanolamine, followed by ultrasonic dispersion for 12 min to obtain treated lithium slag;

[0102] (3) 0.5 g of maleic acid was prepared into an aqueous solution with a pH value of 4.9, 6.3 g of silane coupling agent KH-570 was added thereto under stirring conditions of 598 r / min and hydrolyzed for 15 min to obtain a silane coupling agent treatment solution;

[0103] (4) adding the silane coupling agent treatment solution obtained in step (3) and 0.7 g of maleic acid to the treated lithium slag prepared in step (2) in sequence, stirring with a magnetic force of 789 rpm at room temperature for 7.0 h, and then vacuum drying at 40° C. until the moisture is completely removed to obtain a mixture;

[0104] (5) To the mixture prepared in step (4), 4.8 g of triisopropanolamine and 18.9 g of calcium formate were added in sequence, and then placed in a mixer and mixed at 55 r / min for 40 min to obtain the cement strength enhancer.

[0105] Example 7

[0106] (1) The lithium slag was dried at 40°C to a moisture content of 0.2 wt% and then ground to a specific surface area of 345.9 m 2 / kg;

[0107] (2) 80 g of the lithium slag prepared in step (1) was added with 103.70 g of a 2.7 wt % aqueous solution of triisopropanolamine, followed by ultrasonic dispersion for 11 min to obtain treated lithium slag;

[0108] (3) 0.6 g of oxalic acid was prepared into an aqueous solution with a pH value of 4.1, 7.8 g of silane coupling agent KH-570 was added thereto under stirring conditions of 555 r / min and hydrolyzed for 10 min to obtain a silane coupling agent treatment solution;

[0109] (4) adding the silane coupling agent treatment solution obtained in step (3) and 1.0 g of oxalic acid to the treated lithium slag prepared in step (2) in sequence, stirring at 720 r / min under room temperature for 6.1 h, and then vacuum drying at 43° C. until the moisture is completely removed to obtain a mixture;

[0110] (5) To the mixture prepared in step (4), 5.9 g of tetrahydroxyethylethylenediamine and 15.6 g of sodium thiocyanate were added in sequence, and then placed in a mixer and mixed at 53 r / min for 59 min to obtain the cement strength enhancer.

[0111] Example 8

[0112] (1) The lithium slag was dried at 45°C to a moisture content of 0.4 wt% and then ground to a specific surface area of 329.4 m 2 / kg;

[0113] (2) 82 g of the lithium slag prepared in step (1) was added with 62.86 g of a 3.5 wt% aqueous solution of hydroxyethyl diisopropanolamine, followed by ultrasonic dispersion for 10 min to obtain treated lithium slag;

[0114] (3) 0.8 g of fumaric acid was prepared into an aqueous solution with a pH value of 3.2, 6.5 g of silane coupling agent KH-570 was added thereto under stirring conditions of 586 r / min and hydrolyzed for 12 min to obtain a silane coupling agent treatment solution;

[0115] (4) adding the silane coupling agent treatment solution obtained in step (3) and 1.1 g of fumaric acid to the treated lithium slag prepared in step (2) in sequence, stirring with a magnetic force of 653 r / min at room temperature for 6.0 h, and then vacuum drying at 41° C. until the moisture is completely removed to obtain a mixture;

[0116] (5) 6.0 g of diethanol monoisopropanolamine and 10.1 g of lithium carbonate were added to the mixture prepared in step (4) in sequence, and then placed in a mixer and mixed at 50 r / min for 36 min to obtain the cement strength enhancer.

[0117] Example 9

[0118] (1) The lithium slag was dried at 42°C to a moisture content of 0.6 wt% and then ground to a specific surface area of 395.2 m 2 / kg;

[0119] (2) 75 g of the lithium slag prepared in step (1) was added with 113.04 g of a 2.3 wt% aqueous solution of triethanolamine, followed by ultrasonic dispersion for 15 min to obtain treated lithium slag;

[0120] (3) 0.5 g of maleic anhydride was prepared into an aqueous solution with a pH value of 3.8, 8.0 g of silane coupling agent KH-570 was added thereto under stirring conditions of 435 r / min and hydrolyzed for 14 min to obtain a silane coupling agent treatment solution;

[0121] (4) adding the silane coupling agent treatment solution obtained in step (3) and 0.5 g of maleic anhydride to the treated lithium slag prepared in step (2) in sequence, stirring with a magnetic force of 675 r / min at room temperature for 8.0 h, and then vacuum drying at 44° C. until the moisture is completely removed to obtain a mixture;

[0122] (5) To the mixture prepared in step (4), 4.0 g of triethanolamine and 19.7 g of sodium thiosulfate were added in sequence, and then placed in a mixer and mixed at 56 r / min for 32 min to obtain the cement strength enhancer.

[0123] Example 10

[0124] (1) The lithium slag was dried at 43°C to a moisture content of 0.7 wt% and then ground to a specific surface area of 350.5 m 2 / kg;

[0125] (2) 84 g of the lithium slag prepared in step (1) was added with 52.63 g of a 3.8 wt% aqueous solution of tetrahydroxyethylethylenediamine, followed by ultrasonic dispersion for 12 min to obtain treated lithium slag;

[0126] (3) 0.6 g of malonic acid was prepared into an aqueous solution with a pH value of 3.7, 4.0 g of silane coupling agent KH-570 was added thereto under stirring conditions of 487 r / min and hydrolyzed for 13 min to obtain a silane coupling agent treatment solution;

[0127] (4) adding the silane coupling agent treatment solution obtained in step (3) and 0.2 g of malonic acid to the treated lithium slag prepared in step (2) in sequence, stirring with a magnetic force of 623 r / min at room temperature for 7.0 h, and then vacuum drying at 44° C. until the moisture is completely removed to obtain a mixture;

[0128] (5) To the mixture prepared in step (4), 4.8 g of triisopropanolamine and 13.2 g of sodium pyrosulfate were added in sequence, and then placed in a mixer and mixed at 43 r / min for 44 min to obtain the cement strength enhancer.

[0129] Comparative Example 1

[0130] Repeat Example 1 and grind the lithium slag in step (1) to a specific surface area of 250.3 m 2 / kg, other conditions remain unchanged, as a cement additive.

[0131] Comparative Example 2

[0132] Repeat Example 2 and grind the lithium slag in step (1) to a specific surface area of 465.3 m 2 / kg, other conditions remain unchanged, as a cement additive.

[0133] Comparative Example 3

[0134] Example 3 was repeated, except that the lithium slag was replaced with limestone having no porous structure, and other conditions remained unchanged, as the cement additive.

[0135] Comparative Example 4

[0136] Example 4 was repeated, except that the silane coupling agent was replaced by water of equal mass, and other conditions remained unchanged, as a cement additive.

[0137] Comparative Example 5

[0138] Example 5 was repeated, except that the dibasic organic acid was replaced by an equal mass of water and other conditions remained unchanged, as a cement additive.

[0139] The cement strength enhancers prepared in Examples 1 to 10, the cement additives prepared in Comparative Examples 1 to 5, and a commercially available liquid cement enhancer (mainly composed of triethanolamine, diethanol monoisopropanolamine, and sodium chloride) were tested and evaluated.

[0140] Referring to the test method in GB / T 26748-2011 Cement Grinding Aids, 5 kg of various cement raw materials were added to the test mill according to the P.O.42.5 cement ratio. The cement ratio was: clinker 75%, slag 8%, volcanic ash 7%, fly ash 5%, gypsum 5%. The powder was ground for 25 minutes to obtain a specific surface area of 353.6 m 2 / kg of PO 42.5 cement. Mortar strength was measured according to the test method in GB / T 17671-1999, "Test Method for Cement Mortar Strength (ISO Method)." A test group without any additional materials was used as a blank control group. The cement strength enhancers prepared in Examples 1 to 10, the cement additives prepared in Comparative Examples 1 to 5, and a commercially available liquid cement enhancer were added to the cement to test their enhanced cement strength. The blank group sample dosage was 0%, the samples prepared in Examples 1 to 10 and Comparative Examples 1 to 5 were added at a dosage of 0.4%, and the commercially available liquid cement enhancer was added at a dosage of 0.03%. The results are shown in the following table:

[0141] Table 1 Cement mortar strength

[0142]

[0143] As can be seen from Table 1, compared with the blank, after adding the cement strength enhancer prepared by Example 1 to Example 10, the strength of cement at each age is significantly improved, indicating that the cement strength enhancer effectively promotes the hydration of cement and improves cement strength. Compared with commercially available cement enhancers, the strength of cement at each age is higher, indicating that the cement strength enhancer prepared by Example 1 to Example 10 is significantly better than the commercially available cement enhancer in improving cement strength. Compared with Comparative Example 1 and Comparative Example 2, the cement strength enhancer prepared by Example 1 to Example 10 is more effective in improving cement strength, indicating that changing the grinding specific surface area of lithium slag to make its specific surface area too large or too small will deteriorate the strengthening effect. Compared with Comparative Example 3, the cement strength enhancer prepared by Example 1 to Example 10 is more effective in improving cement strength, indicating that using a material without a porous structure to replace lithium slag does not achieve a better strengthening effect. Compared with Comparative Example 4, the cement strength enhancers prepared in Examples 1 to 10 showed a superior effect on improving cement strength, indicating that without using a silane coupling agent to treat the lithium slag surface, the polyolamine compound filling the pores could not be protected, resulting in a poorer strengthening effect. Compared with Comparative Example 5, the cement strength enhancers prepared in Examples 1 to 10 showed a superior effect on improving cement strength, indicating that without using a dibasic organic acid to provide an acidic environment for the hydrolysis of the silane coupling agent and without treating the lithium slag surface, the coating effect of the silane coupling agent could be affected and the silane coupling agent coating film could not be supplemented, resulting in a poorer strengthening effect.

Claims

1. A cement strength enhancer, characterized in that Prepared by the following method: (1) Dry the lithium slag to a moisture content of <1wt% and grind it to a specific surface area of 300~400m 2 / kg; (2) mixing with an aqueous solution of a polyol amine compound A having a concentration of 2 to 4 wt% to obtain treated lithium slag; (3) preparing a portion of the dibasic organic acid compound into an aqueous solution with a pH value of 3 to 5, adding a silane coupling agent thereto and hydrolyzing for 10 to 15 minutes under stirring to obtain a silane coupling agent treatment solution; (4) adding the silane coupling agent treatment solution obtained in step (3) and the remaining dibasic organic acid compound to the lithium slag obtained in step (2) in sequence, stirring at room temperature for 6 to 8 hours, and vacuum drying at 40 to 45° C. until the moisture is completely removed to obtain a mixture; (5) adding the polyol amine compound B and the inorganic salt compound to the mixture obtained in step (4) in sequence, and then placing the mixture in a mixer and mixing for 30 to 60 minutes to obtain the cement strength enhancer; The raw materials used are as follows by mass: 70~90 parts of lithium slag, 2 to 3 parts of polyol amine compound A, 4 to 8 parts of silane coupling agent, 0.5 to 2 parts of dibasic organic acid compound, 4 to 6 parts of polyol amine compound B, 10 to 20 parts of inorganic salt compound.

2. The cement strength enhancer according to claim 1, characterized in that The lithium slag is waste slag produced by extracting lithium from lithium ore, with a SiO2 content of >50wt%, a CaO content of >10wt%, an Al2O3 content of >15wt%, and a SO3 content of >5wt%.

3. The cement strength enhancer according to claim 1, characterized in that The polyol amine compound A is one of triethanolamine, diethanol monoisopropanolamine, hydroxyethyl diisopropanolamine, triisopropanolamine, tetrahydroxyethyl ethylenediamine, or any mixture thereof.

4. The cement strength enhancer according to claim 1, characterized in that The silane coupling agent is KH-570.

5. The cement strength enhancer according to claim 1, characterized in that The dibasic organic acid compound is one of oxalic acid, malonic acid, maleic acid, and fumaric acid, or any mixture thereof.

6. The cement strength enhancer according to claim 1, characterized in that The polyol amine compound B is one of triethanolamine, diethanol monoisopropanolamine, hydroxyethyl diisopropanolamine, triisopropanolamine, tetrahydroxyethyl ethylenediamine, or any mixture thereof.

7. The cement strength enhancer according to claim 1, characterized in that The inorganic salt compound is one of sodium sulfate, sodium thiosulfate, sodium pyrosulfate, sodium thiocyanate, and lithium carbonate, or any mixture thereof.

8. The method for preparing the cement strength enhancer according to claim 1, characterized in that The following steps are involved: (1) Dry the lithium slag to a moisture content of <1wt% and grind it to a specific surface area of 300~400m 2 / kg; (2) mixing with an aqueous solution of a polyolamine compound A having a concentration of 2 to 4 wt% to obtain treated lithium slag; (3) preparing a portion of the dibasic organic acid compound into an aqueous solution with a pH value of 3 to 5, adding a silane coupling agent thereto and hydrolyzing for 10 to 15 minutes under stirring to obtain a silane coupling agent treatment solution; (4) adding the silane coupling agent treatment solution obtained in step (3) and the remaining dibasic organic acid compound to the lithium slag obtained in step (2) in sequence, stirring at room temperature for 6 to 8 hours, and vacuum drying at 40 to 45° C. until the moisture is completely removed to obtain a mixture; (5) Adding the polyol amine compound B and the inorganic salt compound to the mixture obtained in step (4) in sequence, and then placing the mixture in a mixer and mixing for 30 to 60 minutes to obtain the cement strength enhancer.

9. The use of the cement strength enhancer according to claim 1 in cement, characterized in that The dosage of the cement strength enhancer is 0.3-0.5 wt% of the cement mass.

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