Modified q-phase mineral-based cement chromium removal early strength agent and application thereof
By modifying the ions of the Q-phase minerals and using a rapid cooling process, the problems of insufficient stability and early strength of chromium (VI) in cement were solved, achieving efficient and stable chromium (VI) curing and improved early strength of cement.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-04-01
- Publication Date
- 2026-06-05
AI Technical Summary
Existing technologies struggle to achieve both rapid early strength and long-term stability, and traditional chromium removal agents are prone to oxidation and failure, leading to an increase in the water-soluble chromium (VI) content in cement, posing environmental and human health risks.
By using modified Q-phase minerals as the core component, and by introducing Ba2+, Sr2+ and transition metal divalent ions M2+, combined with a rapid quenching process, highly active hydration products are formed, achieving multi-path synergistic solidification and stability of chromium (VI).
It significantly improves the early strength of cement and reduces the leaching risk of chromium (VI) in cement stone by fixing chromium (VI) through the highly active hydration of modified Q phase minerals and AFm hydration products, thus achieving high chromium removal efficiency and long-lasting effect.
Smart Images
Figure CN122145061A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of cement materials, specifically to a cement chromium removal early strength agent based on modified Q-phase minerals and its application. Background Technology
[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.
[0003] Water-soluble chromium (VI) is classified as a Group 1 carcinogen by the World Health Organization (WHO) and has attracted widespread attention from researchers due to its extreme toxicity and significant threat to human health. To control the water-soluble chromium (VI) content in cement, the national mandatory standard GB 31893-2015 clearly stipulates that the water-soluble chromium (VI) content in cement should not exceed 10 mg / kg. However, with the advancement of comprehensive resource utilization in the cement industry, large amounts of chromium-containing industrial slag, municipal solid waste, and biomass residues are being used to replace natural raw materials in cement clinker production. This resource utilization process objectively introduces chromium into the kiln system, leading to a significant increase in the water-soluble chromium (VI) content in the clinker and its leaching risk, thus posing a new environmental hazard.
[0004] To address the environmental and human health hazards of water-soluble chromium (VI) in cement, reducing agents such as ferrous sulfate are typically added to reduce chromium (VI) to the less toxic chromium (III). However, these additives are unstable, easily oxidized, and have poor long-term effectiveness; excessive introduction can even lead to a decrease in the compressive strength of cement materials. Furthermore, common early-strength agents on the market (such as chlorides and sulfates) compete with chromate ions, resulting in an increase in water-soluble chromium (VI). It is evident that these traditional techniques suffer from incompatibility issues between additives and inconsistent chromium removal efficiency. Summary of the Invention
[0005] To address the current lack of a cement admixture that combines rapid early strength, synergistic curing of chromium (VI) through multiple pathways, and long-term stability, this invention provides a cement chromium removal early strength agent based on modified Q-phase minerals and its application. This agent utilizes Ba... 2+ 、Sr 2+ and transition metal divalent ions M 2+ By combining rapid quenching to lock defect sites, a staged synergistic mechanism is achieved between the highly active hydration of the modified Q phase and the adsorption / intercalation and solidification of hydration products such as AFm, thus achieving both rapid chromium removal and long-term stability. Specifically, the technical solution of this invention is as follows.
[0006] First, this invention provides a cement chromium removal early-strength agent based on modified Q-phase minerals, comprising the following components: 60-80 parts by weight of modified Q-phase minerals, 1-10 parts by weight of synergistic chromium removal functional components, 5-10 parts by weight of setting accelerator, 1-5 parts by weight of sulfate activator, and 10-30 parts by weight of dispersion carrier. The modified Q-phase mineral has the chemical formula 20CaO·3MgO·17Al2O3·3SiO2, and contains Ba2O3 present in a lattice solution and defect compensation manner. 2+ 、Sr 2+ and transition metal divalent ions M 2+ .
[0007] Furthermore, the transition metal divalent ion includes: Zn 2+ Ni 2+ Cu 2+ One or more of them.
[0008] Further, the synergistic chromium removal functional component includes at least one of the following: layered bimetallic hydroxide, iron-based active component, and reducing sulfur-containing component. Optionally, the layered bimetallic hydroxide includes Mg6Al2(CO3)(OH). 16 ·4H2O, Ca4A l2 (OH) 12 One or more of CO3·4H2O, etc. The iron-based active component includes one or more of ferric hydroxide, ferric oxide, etc. The reducing sulfur-containing component includes one or more of ferrous sulfate, sodium bisulfite, etc.
[0009] Furthermore, the coagulant includes one or more of lithium sulfate, calcium formate, calcium nitrate, and triethanolamine.
[0010] Furthermore, the sulfate activator includes one or more of anhydrous sodium sulfate, gypsum dihydrate, and anhydrite.
[0011] Furthermore, the dispersion carrier includes one or more of fly ash, silica fume, metakaolin, etc. One purpose of the dispersion carrier is to reduce the agglomeration of modified Q-phase minerals and synergistic functional components and improve the uniformity of addition.
[0012] Furthermore, the modified Q-phase mineral is prepared by the following method: a calcium source, an aluminum source, a magnesium source, a silicon source, and a modified ion source are mixed and calcined. After calcination, the resulting calcined product is rapidly cooled to room temperature to obtain the mineral. The modified ion source is formed from a barium source, a strontium source, and a divalent transition metal ion source.
[0013] Furthermore, the molar ratio of the calcium source, aluminum source, magnesium source, and silicon source after conversion to CaO, Al2O3, MgO, and SiO2 is 18~22:16~18:2.5~3.5:2.5~3.5.
[0014] Furthermore, after the calcium source, aluminum source, magnesium source, and silicon source are converted to CaO, Al2O3, MgO, and SiO2 respectively, the total mass of the modified ion source converted to BaO, SrO, and MO (divalent transition metal oxides) is 0.1~1.5% of the total mass of CaO, Al2O3, MgO, and SiO2.
[0015] Furthermore, the mass ratio of the barium source, strontium source, and divalent transition metal ion source, after being converted to BaO, SrO, and MO respectively, is 1~3:1~3:0.5~2.
[0016] Furthermore, the calcium source includes at least one of calcium oxide, calcium hydroxide, and calcium carbonate.
[0017] Furthermore, the aluminum source includes one or more of aluminum oxide, aluminum hydroxide, etc.
[0018] Furthermore, the magnesium source includes one or more of magnesium oxide, magnesium carbonate, and basic magnesium carbonate.
[0019] Furthermore, the silicon source includes one or more of silicon dioxide, quartz powder, etc.
[0020] Furthermore, the barium source includes one or more of barium carbonate, barium sulfate, and barium nitrate.
[0021] Furthermore, the strontium source includes one or more of strontium carbonate, strontium sulfate, and strontium nitrate.
[0022] Further, the divalent transition metal ion source includes one or more of zinc ion source, nickel ion source, and copper ion source. Optionally, the zinc ion source includes one or more of zinc oxide, zinc carbonate, zinc sulfate, and zinc nitrate. The nickel ion source includes one or more of nickel oxide, nickel carbonate, and nickel nitrate. The copper ion source includes one or more of copper oxide, copper carbonate, and basic copper carbonate.
[0023] Furthermore, the calcination temperature is 1300~1350℃, and the time is 30~60min.
[0024] Furthermore, the rapid cooling method involves cooling the calcined product to below 200°C within a time of no more than 3 minutes.
[0025] Secondly, this invention provides the application of the modified Q-phase mineral-based cement chromium removal early strength agent in cement-based materials. Optionally, the dosage of the chromium removal early strength agent is 0.05~0.2% of the mass of cement clinker in the cement-based material.
[0026] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects: This invention utilizes a modified Q phase as a core component in a cement chromium removal and early-strength agent, constructing a novel water-soluble chromium (VI) curing method different from traditional reduction methods. This method not only improves the early mechanical properties of cement but also achieves long-term, stable curing of chromium (VI), providing a dual-effect solution for developing high-performance green cement products. To this end, this invention first introduces Ba during the Q phase formation process... 2+ With Sr 2+ Furthermore, the transition metal divalent ion M is introduced. 2 + By combining rapid quenching after calcination, modified ions enter the Q-phase structure through lattice solid solution or defect compensation, achieving structural control and forming modified Q-phase minerals. This utilizes the differences in the occupancy tendency and local coordination perturbation of different modified ions entering the Q-phase lattice to improve chromium removal efficiency. This is because: the Ba... 2+ With Sr 2+ The charge compensation path is simpler, which is more conducive to participating in the solid solution and defect compensation of the Q phase lattice in an equivalent manner similar to Ca sites, thereby improving the continuous hydration activity of the modified Q phase. Meanwhile, the transition metal divalent ion M... 2+ It can modulate the crystal structure, further enriching the types of incomplete coordination sites and active centers. Through the synergistic modification of these ions, a richer and more balanced distribution of structural defect types and active centers is formed, thereby improving the adsorption / intercalation solidification efficiency of Q-phase minerals for chromate ions and enhancing the stability and reproducibility of chromium removal.
[0027] When the chromium-removing early-strength agent of this invention is incorporated into cement, on the one hand, the rapid hydration characteristics of the modified Q-phase mineral with high hydration activity can significantly accelerate the setting and hardening of cement materials, effectively improving early strength. Moreover, compared with traditional early-strength agents, the chromium-removing early-strength agent of this invention does not contain chloride ions and poses no risk of corrosion to steel bars. On the other hand, by utilizing the characteristic that the core hydration product of the modified Q-phase mineral easily generates AFm in the sulfate ion environment provided by the sulfate activator, chromium (VI) is fixed into the crystal lattice to form a chromium-containing AFm phase. At the same time, the content of free chromium (VI) in the system is reduced through the adsorption, complexation, or reduction of the synergistic chromium-removing functional components; multi-path synergistic solidification of chromium (VI) is achieved, thereby reducing the risk of chromium (VI) leaching from cement stone. The chromium removal efficiency is high and the effect is long-lasting, overcoming the shortcomings of traditional reducing chromium removal agents such as ferrous sulfate that are prone to failure. Attached Figure Description
[0028] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention and do not constitute an undue limitation of the invention.
[0029] Figure 1 The image shows a modified Q-phase mineral sample prepared in Example 1 below.
[0030] Figure 2 The XRD pattern is shown for the modified Q-phase mineral prepared in Example 1 below.
[0031] Figure 3 The image shows a sample of the cement chromium removal early strength agent prepared in Example 1 below.
[0032] Figure 4 The image shows a modified Q-phase mineral sample prepared in Example 2 below.
[0033] Figure 5 The image shows a sample of the cement chromium removal early strength agent prepared in Example 2 below.
[0034] Figure 6 The image shows a modified Q-phase mineral sample prepared in Example 3 below.
[0035] Figure 7 The image shows a sample of the cement chromium removal early strength agent prepared in Example 3 below.
[0036] Figure 8 The XRD pattern of the Q phase mineral prepared in Example 4 below. Detailed Implementation
[0037] The technical solution of the present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the manufacturer.
[0038] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as those skilled in the art. The reagents or raw materials used in this invention are readily available through conventional means. Unless otherwise specified, the reagents or raw materials used in this invention are used in accordance with conventional methods in the art or according to the product instructions. The technical solution of this invention will now be further described in conjunction with the accompanying drawings and specific embodiments.
[0039] Example 1 A method for preparing a cement chromium removal early strength agent based on modified Q-phase minerals includes the following steps: (1) Weigh each raw material according to the following ratios: calcium source (calcium carbonate), aluminum source (alumina), magnesium source (magnesium carbonate), and silicon source (silicon dioxide), converted to CaO, Al2O3, MgO, and SiO2 respectively, with a molar ratio of 20:17:3:3. Then add barium source (barium carbonate), strontium source (strontium carbonate), and divalent transition metal ion source (zinc oxide) as modified ion sources. The total mass of these modified ion sources, after being converted to BaO, SrO, and ZnO respectively, accounts for 0.5% of the total mass of the CaO, Al2O3, MgO, and SiO2, wherein the mass ratio of BaO, SrO, and ZnO is 2:2:1. Add the above powder raw materials to water to form a uniform slurry for later use.
[0040] (2) The slurry was transferred to a 60 ℃ oven and dried for 24 h. The resulting dried raw material mixture was ground into powder and pressed into raw material cakes. The raw material cakes were then placed in a heating furnace and heated to 1350 ℃ at a heating rate of 5 ℃ / min and held for 60 min for calcination. After completion, the calcined product was taken out and immediately subjected to forced air cooling, which reduced the temperature to below 200 ℃ within 3 min, and then continued to cool naturally to room temperature. Finally, the obtained solid was ball-milled at a speed of 500 r / min for 40 min to obtain powdered modified Q phase minerals. The physical sample and XRD test results are as follows: Figure 1 , Figure 2 As shown.
[0041] (3) Take the following raw materials in the following proportions: 70 parts by weight of the modified Q phase mineral of this embodiment, 2 parts by weight of ferrous sulfate, 5 parts by weight of calcium formate, 3 parts by weight of gypsum dihydrate, and 20 parts by weight of fly ash. Ball mill the above raw materials at a speed of 500 r / min for 40 min to obtain the cement chromium removal early strength agent. The physical sample is shown below. Figure 3 As shown.
[0042] Performance testing: (1) The chromium removal rate of the cement chromium removal early strength agent prepared in this embodiment was measured according to GB 31893-2015 "Limits and determination methods for water-soluble chromium (VI) in cement". The result was 90.81%. (2) The cement chromium removal early strength agent prepared in this embodiment was added to the cement at a dosage of 0.1% of the cement composition. Then, the 1-day compressive strength of the specimen was tested according to GB / T 17671-1999 "Test method for strength of cement mortar (ISO method)" and the 3-day compressive strength was 27.1 MPa.
[0043] Example 2 A method for preparing a cement chromium removal early strength agent based on modified Q-phase minerals includes the following steps: (1) Weigh each raw material according to the following ratios: calcium source (calcium hydroxide), aluminum source (alumina), magnesium source (magnesium oxide), and silicon source (silicon dioxide), converted to CaO, Al2O3, MgO, and SiO2 respectively, with a molar ratio of 18:16:2.5:2.5. Then add barium source (barium sulfate), strontium source (strontium sulfate), and divalent transition metal ion source (nickel carbonate) as modified ion sources. The total mass of these modified ion sources, after being converted to BaO, SrO, and NiO respectively, accounts for 0.1% of the total mass of the CaO, Al2O3, MgO, and SiO2, wherein the mass ratio of BaO, SrO, and NiO is 3:3:2. Add the above powder raw materials to water to form a uniform slurry for later use.
[0044] (2) The slurry was transferred to a 60 ℃ oven and dried for 24 h. The resulting dried raw material mixture was ground into powder and pressed into raw material cakes. The raw material cakes were then placed in a heating furnace and heated to 1300 ℃ at a heating rate of 5 ℃ / min and held for 40 min for calcination. After completion, the calcined product was removed and immediately subjected to forced air cooling, which reduced the temperature to below 200 ℃ within 3 min, and then allowed to cool naturally to room temperature. Finally, the obtained solid was ball-milled at a speed of 500 r / min for 40 min to obtain powdered modified Q phase minerals. The actual sample is shown below. Figure 4 As shown.
[0045] (3) Take the following raw materials in the following proportions: 80 parts by weight of the modified Q phase mineral in this embodiment, and layered bimetallic hydroxide (Mg6Al2(CO3)(OH)). 16 The following ingredients were used: 10 parts by weight of 4H₂O, 10 parts by weight of lithium sulfate, 5 parts by weight of anhydrite, and 30 parts by weight of silica fume. The above raw materials were ball-milled at 500 r / min for 40 min to obtain a cement chromium removal and early-strength agent. A physical sample is shown below. Figure 5 As shown.
[0046] Performance testing: (1) The chromium removal rate of the cement chromium removal early strength agent prepared in this embodiment was measured according to GB 31893-2015 "Limits and Determination Methods for Water-soluble Chromium (VI) in Cement", and the result was 90.19%. (2) The cement chromium removal early strength agent prepared in this embodiment was added to the cement at a dosage of 0.2% of the cement composition. Then, the 1-day compressive strength of the specimen was tested according to GB / T 17671-1999 "Test Method for Strength of Cement Mortar (ISO Method)" and the 3-day compressive strength was 18.5 MPa and 28.3 MPa.
[0047] Example 3 A method for preparing a cement chromium removal early strength agent based on modified Q-phase minerals includes the following steps: (1) Weigh each raw material according to the following ratios: calcium source (calcium oxide), aluminum source (aluminum hydroxide), magnesium source (basic magnesium carbonate), and silicon source (silicon dioxide), converted to CaO, Al2O3, MgO, and SiO2 respectively, with a molar ratio of 22:18:3.5:3.5. Then, add barium source (barium nitrate), strontium source (strontium nitrate), and divalent transition metal ion source (copper carbonate) as modified ion sources. The total mass of these modified ion sources, after being converted to BaO, SrO, and CuO respectively, accounts for 1.5% of the total mass of CaO, Al2O3, MgO, and SiO2, wherein the mass ratio of BaO, SrO, and CuO is 1:1:0.5. Add the above powder raw materials to water to form a uniform slurry for later use.
[0048] (2) The slurry was transferred to a 60 ℃ oven and dried for 24 h. The resulting dried raw material mixture was ground into powder and pressed into raw material cakes. The raw material cakes were then placed in a heating furnace and heated to 1340 ℃ at a heating rate of 5 ℃ / min and held for 30 min for calcination. After completion, the calcined product was removed and immediately subjected to forced air cooling, which reduced the temperature to below 200 ℃ within 3 min, and then allowed to cool naturally to room temperature. Finally, the obtained solid was ball-milled at a speed of 500 r / min for 40 min to obtain powdered modified Q phase minerals. The actual sample is shown below. Figure 6 As shown.
[0049] (3) Take the following raw materials in the following proportions: 60 parts by weight of the modified Q phase mineral of this embodiment, 1 part by weight of ferrous sulfate, 5 parts by weight of calcium formate, 1 part by weight of gypsum dihydrate, and 10 parts by weight of metakaolin powder. Ball mill the above raw materials at a speed of 500 r / min for 40 min to obtain the cement chromium removal early strength agent. The physical sample is shown below. Figure 7 As shown.
[0050] Performance testing: (1) The chromium removal rate of the cement chromium removal early strength agent prepared in this embodiment was measured according to GB 31893-2015 "Limits and determination methods for water-soluble chromium (VI) in cement". The result was 93.15%. (2) The cement chromium removal early strength agent prepared in this embodiment was added to the cement at a dosage of 0.15% of the cement composition. Then, the 1-day compressive strength of the specimen was tested according to GB / T 17671-1999 "Test method for strength of cement mortar (ISO method)" and the 3-day compressive strength was 21.3 MPa and 29.5 MPa.
[0051] Example 4 A method for preparing a cement chromium removal early strength agent based on Q-phase minerals includes the following steps: (1) Weigh each raw material according to the molar ratio of 20:17:3:3 after converting the calcium source (calcium carbonate), aluminum source (alumina), magnesium source (magnesium carbonate), and silicon source (silicon dioxide) to CaO, Al2O3, MgO, and SiO2, respectively. Add the above powder raw materials to water to form a uniform slurry for later use.
[0052] (2) The slurry was transferred to a 60 ℃ oven and dried for 24 h. The resulting dried raw material mixture was ground into powder and pressed into raw material cakes. The raw material cakes were then placed in a heating furnace and heated to 1350 ℃ at a heating rate of 5 ℃ / min and held for 60 min for calcination. After completion, the calcined product was removed and immediately subjected to forced air cooling, which reduced the temperature to below 200 ℃ within 3 min, and then allowed to cool naturally to room temperature. Finally, the obtained solid was ball-milled at a speed of 500 r / min for 40 min to obtain powdered Q phase minerals. The XRD test results are as follows: Figure 8 As shown.
[0053] (3) Take the following raw materials in the following proportions: 70 parts by weight of the Q phase mineral powder, 2 parts by weight of ferrous sulfate, 5 parts by weight of calcium formate, 3 parts by weight of gypsum dihydrate, and 20 parts by weight of fly ash. Ball mill the above raw materials at a speed of 500 r / min for 40 min to obtain the cement chromium removal early strength agent.
[0054] Performance testing: (1) The chromium removal rate of the cement chromium removal early strength agent prepared in this embodiment was measured according to GB 31893-2015 "Limits and determination methods for water-soluble chromium (VI) in cement". The result was 50.34%. (2) The cement chromium removal early strength agent prepared in this embodiment was added to the cement at a dosage of 0.1% of the cement composition. Then, the 1-day compressive strength of the specimen was tested according to GB / T 17671-1999 "Test method for strength of cement mortar (ISO method)" and the 3-day compressive strength was 20.2 MPa.
[0055] Example 5 A method for preparing a cement chromium removal early strength agent based on modified Q-phase minerals includes the following steps: (1) Weigh each raw material according to the following ratios: calcium source (calcium carbonate), aluminum source (alumina), magnesium source (magnesium carbonate), and silicon source (silicon dioxide), converted to CaO, Al2O3, MgO, and SiO2 respectively, with a molar ratio of 20:17:3:3. Then, add barium source (barium carbonate) and strontium source (strontium carbonate) as modified ion sources. The total mass of these modified ion sources, after being converted to BaO and SrO respectively, accounts for 0.4% of the total mass of the CaO, Al2O3, MgO, and SiO2, wherein the mass ratio of BaO to SrO is 2:2. Add the above powder raw materials to water to form a uniform slurry for later use.
[0056] (2) The slurry was transferred to a 60 °C oven and dried for 24 h. The resulting dried raw material mixture was ground into powder and pressed into raw material cakes. The raw material cakes were then placed in a heating furnace and heated to 1350 °C at a heating rate of 5 °C / min and held for 60 min for calcination. After completion, the calcined product was removed and immediately subjected to forced air cooling, which reduced the temperature to below 200 °C within 3 min, and then allowed to cool naturally to room temperature. Finally, the obtained solid was ball-milled at a speed of 500 r / min for 40 min to obtain powdered modified Q phase minerals.
[0057] (3) Take the following raw materials in the following proportions: 70 parts by weight of the modified Q phase mineral in this embodiment, 2 parts by weight of ferrous sulfate, 5 parts by weight of calcium formate, 3 parts by weight of gypsum dihydrate, and 20 parts by weight of fly ash. Ball mill the above raw materials at a speed of 500 r / min for 40 min to obtain the cement chromium removal early strength agent.
[0058] Performance testing: (1) The chromium removal rate of the cement chromium removal early strength agent prepared in this embodiment was measured according to GB 31893-2015 "Limits and Determination Methods for Water-soluble Chromium (VI) in Cement", and the result was 65.61%. (2) The cement chromium removal early strength agent prepared in this embodiment was added to the cement at a dosage of 0.1% of the cement composition. Then, the 1-day compressive strength of the specimen was tested according to GB / T 17671-1999 "Test Method for Strength of Cement Mortar (ISO Method)" and the 3-day compressive strength was 21.2 MPa.
[0059] Example 6 A method for preparing a cement chromium removal early strength agent based on modified Q-phase minerals includes the following steps: (1) Weigh each raw material according to the following ratios: calcium source (calcium hydroxide), aluminum source (alumina), magnesium source (magnesium oxide), and silicon source (silicon dioxide), converted to CaO, Al2O3, MgO, and SiO2 respectively, with a molar ratio of 18:16:2.5:2.5. Then, add barium source (barium sulfate) and divalent transition metal ion source (nickel carbonate) as modified ion sources. The total mass of these modified ion sources, after being converted to BaO and NiO respectively, accounts for 0.0625% of the total mass of CaO, Al2O3, MgO, and SiO2, wherein the mass ratio of BaO to NiO is 3:2. Add the above powder raw materials to water to form a uniform slurry for later use.
[0060] (2) The slurry was transferred to a 60 °C oven and dried for 24 h. The resulting dried raw material mixture was ground into powder and pressed into raw material cakes. The raw material cakes were then placed in a heating furnace and heated to 1300 °C at a heating rate of 5 °C / min and held for 40 min for calcination. After completion, the calcined product was removed and immediately subjected to forced air cooling, which reduced the temperature to below 200 °C within 3 min, and then allowed to cool naturally to room temperature. Finally, the obtained solid was ball-milled at a speed of 500 r / min for 40 min to obtain powdered modified Q phase minerals.
[0061] (3) Take the following raw materials in the following proportions: 80 parts by weight of the modified Q phase mineral in this embodiment, and layered bimetallic hydroxide (Mg6Al2(CO3)(OH)). 16 The following ingredients are used: 10 parts by weight of 4H2O, 10 parts by weight of lithium sulfate, 5 parts by weight of anhydrite, and 30 parts by weight of silica fume. The above raw materials are ball-milled at 500 r / min for 40 min to obtain a cement chromium removal and early-strength agent.
[0062] Performance testing: (1) The chromium removal rate of the cement chromium removal early strength agent prepared in this embodiment was measured according to GB 31893-2015 "Limits and Determination Methods for Water-soluble Chromium (VI) in Cement", and the result was 61.56%. (2) The cement chromium removal early strength agent prepared in this embodiment was added to the cement at a dosage of 0.2% of the cement composition. Then, the 1-day compressive strength of the specimen was tested according to GB / T 17671-1999 "Test Method for Strength of Cement Mortar (ISO Method)" and the 3-day compressive strength was 15.2 MPa and 21.6 MPa.
[0063] Example 7 A method for preparing a cement chromium removal early strength agent based on modified Q-phase minerals includes the following steps: (1) Weigh each raw material according to the following ratios: calcium source (calcium oxide), aluminum source (aluminum hydroxide), magnesium source (basic magnesium carbonate), and silicon source (silicon dioxide), after being converted to CaO, Al2O3, MgO, and SiO2 respectively, with a molar ratio of 22:18:3.5:3.5. Then, add strontium source (strontium nitrate) and divalent transition metal ion source (copper carbonate) as modified ion sources. The total mass of these modified ion sources, after being converted to SrO and CuO respectively, accounts for 0.9% of the total mass of the CaO, Al2O3, MgO, and SiO2, wherein the mass ratio of SrO to CuO is 1:0.5. Add the above powder raw materials to water to form a uniform slurry for later use.
[0064] (2) The slurry was transferred to a 60 °C oven and dried for 24 h. The resulting dried raw material mixture was ground into powder and pressed into raw material cakes. The raw material cakes were then placed in a heating furnace and heated to 1340 °C at a heating rate of 5 °C / min and held for 30 min for calcination. After completion, the calcined product was removed and immediately subjected to forced air cooling, which reduced the temperature to below 200 °C within 3 min, and then allowed to cool naturally to room temperature. Finally, the obtained solid was ball-milled at 500 r / min for 40 min to obtain powdered modified Q phase minerals.
[0065] (3) Take the following raw materials in the following proportions: 60 parts by weight of the modified Q phase mineral of this embodiment, 1 part by weight of ferrous sulfate, 5 parts by weight of calcium formate, 1 part by weight of gypsum dihydrate, and 10 parts by weight of metakaolin powder. Ball mill the above raw materials at a speed of 500 r / min for 40 min to obtain the cement chromium removal early strength agent.
[0066] Performance testing: (1) The chromium removal rate of the cement chromium removal early strength agent prepared in this embodiment was measured according to GB 31893-2015 "Limits and Determination Methods for Water-soluble Chromium (VI) in Cement", and the result was 78.15%. (2) The cement chromium removal early strength agent prepared in this embodiment was added to the cement at a dosage of 0.15% of the cement composition. Then, the 1-day compressive strength of the specimen was tested according to GB / T 17671-1999 "Test Method for Strength of Cement Mortar (ISO Method)" and the 3-day compressive strength was 22.1 MPa.
[0067] Example 8 A method for preparing a cement chromium removal early strength agent based on modified Q-phase minerals includes the following steps: Take the following raw materials in the following proportions: 80 parts by weight of the modified Q-phase mineral powder from Example 2 above, and layered bimetallic hydroxide (Mg6Al2(CO3)(OH)). 16 The following ingredients are used: 10 parts by weight of 4H2O, 10 parts by weight of lithium sulfate, and 30 parts by weight of silica fume. The above raw materials are ball-milled at 500 r / min for 40 min to obtain a cement chromium removal and early strength agent.
[0068] Performance testing: (1) The chromium removal rate of the cement chromium removal early strength agent prepared in this embodiment was measured according to GB 31893-2015 "Limits and determination methods for water-soluble chromium (VI) in cement". The result was 51.34%. (2) The cement chromium removal early strength agent prepared in this embodiment was added to the cement at a dosage of 0.2% of the cement composition. Then, the 1-day compressive strength of the specimen was tested according to GB / T 17671-1999 "Test method for strength of cement mortar (ISO method)" and the 3-day compressive strength was 13.5 MPa and 19.2 MPa.
[0069] The above are merely some preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A cement chromium removal early-strength agent based on modified Q-phase minerals, characterized in that, It includes the following components: 60-80 parts by weight of modified Q-phase minerals, 1-10 parts by weight of synergistic chromium removal functional components, 5-10 parts by weight of coagulant accelerator, 1-5 parts by weight of sulfate activator, and 10-30 parts by weight of dispersion carrier; wherein: The modified Q-phase mineral has the chemical formula 20CaO·3MgO·17Al2O3·3SiO2, and contains Ba in the form of lattice solid solution and defect compensation. 2+ 、Sr 2+ and transition metal divalent ions M 2+ .
2. The cement chromium removal early strength agent based on modified Q-phase minerals according to claim 1, characterized in that, The transition metal divalent ions include: Zn 2+ Ni 2+ Cu 2+ One or more of them.
3. The cement chromium removal early strength agent based on modified Q-phase minerals according to claim 1, characterized in that, The synergistic chromium removal functional component includes at least one of the following: layered bimetallic hydroxide, iron-based active component, and reducing sulfur-containing component; Optionally, the layered bimetallic hydroxide includes Mg6Al2(CO3)(OH). 16 ·4H2O, Ca4A l2 (OH) 12 One or more of CO3·4H2O; Optionally, the iron-based active component includes one or more of iron hydroxide and iron oxide; Optionally, the reducing sulfur-containing component includes one or more of ferrous sulfate and sodium bisulfite.
4. The cement chromium removal early strength agent based on modified Q-phase minerals according to claim 1, characterized in that, The coagulant includes one or more of lithium sulfate, calcium formate, calcium nitrate, and triethanolamine. Optionally, the sulfate activator includes one or more of anhydrous sodium sulfate, gypsum dihydrate, and anhydrite. Optionally, the dispersion carrier includes one or more of fly ash, silica fume, and metakaolin.
5. The cement chromium removal early strength agent based on modified Q-phase minerals according to any one of claims 1-4, characterized in that, The modified Q-phase mineral is prepared by the following method: calcium source, aluminum source, magnesium source, silicon source and modified ion source are mixed and calcined. After completion, the calcined product is rapidly cooled to room temperature to obtain the modified ion source. The modified ion source is formed by barium source, strontium source and divalent transition metal ion source.
6. The cement chromium removal early strength agent based on modified Q-phase minerals according to claim 5, characterized in that, The molar ratios of the calcium source, aluminum source, magnesium source, and silicon source, after being converted to CaO, Al2O3, MgO, and SiO2, are 18~22:16~18:2.5~3.5:2.5~3.5, respectively. Optionally, after the calcium source, aluminum source, magnesium source, and silicon source are converted to CaO, Al2O3, MgO, and SiO2 respectively, the total mass of the modified ion source converted to BaO, SrO, and MO is 0.1~1.5% of the total mass of CaO, Al2O3, MgO, and SiO2. Optionally, the mass ratio of the barium source, strontium source, and divalent transition metal ion source, after being converted to BaO, SrO, and MO respectively, is 1~3:1~3:0.5~2.
7. The cement chromium removal early strength agent based on modified Q-phase minerals according to claim 5, characterized in that, The calcium source includes at least one of calcium oxide, calcium hydroxide, and calcium carbonate. Optionally, the aluminum source includes one or more of aluminum oxide and aluminum hydroxide; Optionally, the magnesium source includes one or more of magnesium oxide, magnesium carbonate, and basic magnesium carbonate; Optionally, the silicon source includes one or more of silicon dioxide and quartz powder; Optionally, the barium source includes one or more of barium carbonate, barium sulfate, and barium nitrate; Optionally, the strontium source includes one or more of strontium carbonate, strontium sulfate, and strontium nitrate.
8. The cement chromium removal early strength agent based on modified Q-phase minerals according to claim 5, characterized in that, The divalent transition metal ion source includes one or more of zinc ion source, nickel ion source, and copper ion source; Optionally, the zinc ion source includes one or more of zinc oxide, zinc carbonate, zinc sulfate, and zinc nitrate. Optionally, the nickel ion source includes one or more of nickel oxide, nickel carbonate, and nickel nitrate; Optionally, the copper ion source includes one or more of copper oxide, copper carbonate, and basic copper carbonate.
9. The cement chromium removal early strength agent based on modified Q-phase minerals according to claim 5, characterized in that, The calcination temperature is 1300~1350℃, and the time is 30~60min; Preferably, the rapid cooling method involves cooling the calcined product to below 200°C within a time not exceeding 3 minutes.
10. The application of the cement chromium removal early strength agent based on modified Q phase minerals according to any one of claims 1-9 in cement-based materials; optionally, the dosage of the chromium removal early strength agent is 0.05~0.2% of the mass of cement clinker in the cement-based material.