Sulfur Portland cement and preparation method thereof

Abstract

The invention relates to sulfur silicate cement and a preparation method thereof. Relates to the technical field of cement. Comprising sulfur silicate clinker, gypsum, a mixed material and a performance adjusting component, the sulfur silicate cement comprises the following components in parts by mass: 50-90 parts of sulfur silicate clinker, 4-25 parts of gypsum, 5-50 parts of a mixed material and 0-5 parts of a performance adjusting component. The mineral composition of the sulfur silicate clinker is as follows: 15 to 50 weight percent of calcium sulphoaluminate, 5 to 50 weight percent of calcium sulphosilicate, 10 to 70 weight percent of dicalcium silicate, 2 to 15 weight percent of free gypsum and 0 to 2 weight percent of free lime; the 45-micron screen residue of the sulfur silicate clinker is less than or equal to 25%. According to the invention, under the condition that the mineral composition of the sulfur silicate clinker is changed, the hydration degree of the clinker is improved and the consumption of the clinker is saved by compounding the proper gypsum and the admixture, the clinker coefficient can reach 0.5-1, and the cement cost and carbon emission are effectively reduced.

Description

Technical Field

[0001] The invention relates to the technical field of cement, and in particular to a sulpho-silicate cement and a preparation method thereof. Technical Background

[0002] The cement industry is an industry with high CO2 emissions. One ton of cement clinker emits about 0.8-1.0 t of CO2. According to big data, the amount of CO2 emitted by cement production can account for 6-8% of the total global industrial CO2 emissions. In recent years, in order to reduce carbon emissions in the cement industry, new low-carbon cement has become a research focus. The main goal of low-carbon cement development technology is to find alternative minerals to tricalcium silicate and explore new low-emission and low-energy clinker systems. A sulpho-silicate cement clinker composed of low-calcium minerals such as calcium sulpho-silicate, calcium sulphoaluminate and dicalcium silicate has become the focus of industry research. Sulpho-silicate cement clinker has the advantages of high early strength, fast setting speed, micro-expansion, good erosion resistance and frost resistance.

[0003] How to utilize sulphur-silicate cement clinker and improve the performance of cement is the current problem. Summary of the invention

[0004] In order to improve the fluidity of sulphosilane cement, prolong the setting time of sulphosilane cement, increase the durability of sulphosilane cement, and reduce the carbon emission of sulphosilane cement, the present invention proposes a sulphosilane cement and a preparation method thereof, wherein sulphosilane cement with good hydration activity, suitable setting time and good durability is formed by compounding sulphosilane cement clinker, gypsum and admixtures.

[0005] The technical solution of the present invention is: a sulpho-silicate cement, comprising: sulpho-silicate clinker, gypsum, admixture and performance regulating component; In terms of mass fraction, the sulpho-silicate cement comprises: 50-90 parts of sulpho-silicate clinker, 4-25 parts of gypsum, 5-50 parts of admixtures and 0-5 parts of performance regulating components.

[0006] The mineral composition of the sulphoaluminate clinker is: 15-50wt.%, calcium sulphoaluminate 5-50wt.%, dicalcium silicate 10-70wt.%, free gypsum 2-15wt.%, and free lime 0-2wt.%; the 45μm sieve residue of the sulphoaluminate clinker is ≤25%.

[0007] The gypsum is a natural raw material or solid waste containing calcium sulfate.

[0008] The mixed material is at least one of fly ash, slag powder, limestone powder, carbide slag, sandstone powder, shale powder, metakaolin, red mud and calcined coal gangue.

[0009] The mixed materials are aluminum-containing mixed materials: fly ash, slag powder, metakaolin, red mud, calcined coal gangue, and non-aluminum-containing mixed materials: limestone powder, carbide slag, sandstone powder, and shale powder.

[0010] The aluminum-containing mixed material begins to depolymerize under the stimulation of calcium hydroxide to form [SiO4] 4- and [AlO4] 5- Aluminum promotes the hydration of calcium sulfosilicate to generate CSH gel, Ca(OH)2 and gypsum. Further, the aluminum admixture can generate ettringite under the action of sulfur, thereby improving the strength of cement. The admixture generates ettringite when gypsum is sufficient.

[0011] The aluminum-free mixed material mainly plays the role of filling pores and improving density.

[0012] The performance adjustment component includes at least one of quicklime, magnesium oxide and an expander.

[0013] The present invention also discloses a method for preparing sulpho-Silicate cement, comprising: The thiosilicate clinker is ground to a 45 μm sieve residue of ≤25%, and the thiosilicate clinker is fully mixed with gypsum to obtain a mixture of thiosilicate clinker and gypsum.

[0014] The sulpho-silicate clinker and gypsum mixture are then configured with a mixed material, and the mixture is fully mixed by a mixing device to prepare sulpho-silicate cement.

[0015] The properties of the sulpho-silicate cement prepared by the invention are as follows: 3-day compressive strength is ≥25MPa, and 28-day strength is ≥48MPa.

[0016] The sulphur silicate cement prepared by the present invention has the following advantages: 1) Under the condition that the mineral composition of sulpho-Silicate cement clinker remains unchanged, different physical properties of sulpho-Silicate cement can be achieved by compounding gypsum and admixtures. The compressive strength performance can be adjusted within 48MPa-70Mpa to adapt to various working conditions.

[0017] 2) When the mineral composition of thiosilicate clinker changes, the hydration degree of clinker can be improved by compounding appropriate gypsum and admixtures, saving clinker consumption. The clinker coefficient can reach 0.5-1, effectively reducing cement costs and carbon emissions.

[0018] 3) The present invention can prepare special cement with special uses through the coordinated hydration of sulphosilicate clinker, gypsum and admixtures. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The XRD diagrams of hydration of sulphur silicate cement at different ages in Example 1. DETAILED DESCRIPTION

[0020] The implementation method of the present invention adopts sulpho-silicate cement clinker, gypsum and admixtures for compounding, thereby improving the physical properties of cement, increasing the hydration activity of cement, ensuring the stable growth of the strength of sulpho-silicate cement, and improving the durability of cement.

[0021] The following embodiments are provided for a better understanding of the present invention, but are not limited to the best mode of implementation, and do not limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0022] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the materials or instruments used, they are all conventional products that can be purchased.

[0023] The sulpho-silicate cement clinker is fired in the laboratory, and the sulpho-silicate clinker is crushed and ground to a specific surface area of ​​more than 350 m2 / kg. First, 92 parts of sulpho-silicate clinker and 8 parts of anhydrite are prepared and mixed according to weight parts to prepare a sulpho-silicate clinker + gypsum mixture.

[0024] Embodiment 1: The mixture of sulpho-silicate clinker and gypsum is prepared into cement according to the weight proportions: (sulpho-silicate clinker + gypsum) 90 parts, slag powder 10 parts. The physical properties of the prepared cement are shown in Appendix 1: Through XRD, we can know that Figure 1 The early hydration products of sulphosilane cement shown are: AFt and Al(OH)3 gel; the later hydration products are: AFt, CS(A)-H gel. The early reaction of sulphosilane cement is mainly the hydration of calcium sulphoaluminate, which generates Aft and Al(OH)3 gel with gypsum. When the curing age is 7 to 14 days, the Al(OH)3 gel generated by the hydration of calcium sulphoaluminate promotes the hydration of calcium sulphosilane to generate gypsum and highly active α-C2S, and further hydration generates CSH gel and Ca(OH)2 to increase the alkalinity in cement, so that the slag powder begins to depolymerize and dissolve [SiO4] 4- and [AlO4] 5- During the curing period of 14 to 28 days, the dicalcium silicate in the clinker begins to react, compensating for the decrease in alkalinity caused by slag hydration, and continuously promoting slag hydration. Specifically, slag hydration consumes alkaline substances and calcium sulfosilicate in the system, and the slag begins to depolymerize under the stimulation of calcium hydroxide to form dissolved [SiO4] 4- and [AlO4] 5-Aluminum promotes the hydration of calcium sulfosilicate to generate CSH gel, Ca(OH)2 and gypsum. Further, slag can generate ettringite under the action of sulfur, thus improving the strength of cement. When gypsum is sufficient, the admixture generates ettringite. The hydration of dicalcium silicate continuously supplements alkaline substances to keep the hydration reaction of slag going.

[0025] The stability of cement was tested according to the boiling method in standard GB / T 1346-2011 "Test methods for water consumption, setting time and stability of cement of standard consistency", and the results all met the standards.

[0026] Embodiment 2: The mixture of sulpho-silicate clinker and gypsum is prepared into cement according to the weight proportions: 70 parts of (sulpho-silicate clinker + gypsum), 5 parts of calcined coal gangue powder, and 25 parts of fly ash to obtain sulpho-silicate cement. The physical properties of the prepared cement are shown in Appendix 1: The spherical particles of fly ash are beneficial to reduce the internal friction between particles in cement paste, improve the fluidity of water paste, effectively disperse cement particles, and improve fluidity. Compared with sulfur-silica cement with simple addition of slag powder, adding fly ash increases the density of cement and improves the early strength of cement.

[0027] The stability of cement was tested according to the boiling method in standard GB / T 1346-2011 "Test methods for water consumption, setting time and stability of cement of standard consistency", and the results all met the standards.

[0028] Embodiment 3: The mixture of sulpho-silicate cement clinker and gypsum is prepared into cement according to the following weight proportions: (sulpho-silicate clinker + gypsum) 65 parts, metakaolin 30 parts, limestone powder 4 parts, carbide slag 1 part to obtain sulpho-silicate cement. The physical properties of the prepared cement are shown in Appendix 1: The alkalinity of sulpho-Silicate cement is low in the early stage, which cannot promote the rapid hydration of metakaolin. The early addition of carbide slag can increase the alkalinity of sulpho-Silicate cement and facilitate the early hydration of metakaolin. Limestone powder is an inert admixture. It mainly plays a filling role and microcrystalline nucleus role in cement, filling the gaps in the cement sample, improving the density of the test block, and ensuring the stability of the later strength growth.

[0029] The stability of cement was tested according to the boiling method in standard GB / T 1346-2011 "Test methods for water consumption, setting time and stability of cement of standard consistency", and the results all met the standards.

[0030] Embodiment 4: The mixture of sulfosilicate clinker and gypsum is prepared into cement according to the following weight proportions: (sulfosilicate clinker + gypsum) 55 parts, slag powder 15 parts, fly ash 10 parts, red mud 15 parts, sandstone powder 4 parts, quicklime 1 part to obtain sulfosilicate cement. The physical properties of the prepared cement are shown in Appendix 1: The stability of cement was tested according to the boiling method in standard GB / T 1346-2011 "Test methods for water consumption, setting time and stability of cement of standard consistency", and the results all met the standards.

[0031] Embodiment 5: The raw materials were prepared into cement according to weight proportions: 92 parts of sulfosilicate clinker and 8 parts of anhydrite to obtain sulfosilicate cement. Similarly, the anhydrite was replaced with desulfurized gypsum and phosphogypsum in equal weight proportions to prepare desulfurized gypsum sulfosilicate cement and phosphogypsum sulfosilicate cement. The compressive strength of the cement prepared was shown in Table 1 below: Table 1 Compressive strength of different types of gypsum sulphur silicate cement The early hydration rate of anhydrite is relatively fast, and it reacts in water to generate dihydrate gypsum to form needle-shaped crystals, which promotes the development of strength in 3 days.

[0032] Table 2 Setting time of different types of gypsum sulphur silicate cement Desulfurized gypsum and phosphogypsum are both dihydrate gypsum obtained from industrial solid waste. They dissolve relatively slowly in water, so they play a retarding role, as shown in Table 2.

[0033] The raw materials were prepared into cement according to the weight proportions: 92 parts of sulpho-silicate clinker and 4 parts of anhydrite to obtain sulpho-silicate cement. The weight proportions of anhydrite were increased to 8%, 13%, 19%, and 25% by analogy. The compressive strengths are shown in Table 3 below: Table 3 Compressive strength of different amounts of gypsum sulphur silicate cement Increasing the dosage of anhydrite is beneficial to the development of early strength and can be used in working conditions with high requirements for early strength.

[0034] Appendix 1 Physical properties of sulphur-portland cement The present invention can prepare special cement with special uses through the coordinated hydration of sulphosilicate clinker, gypsum and admixtures. For example, rapid hardening and early strength of cement can be achieved by changing the amount of gypsum and the type of admixtures; low heat cement can be achieved by adding admixtures; and high fluidity cement can be achieved by adding admixtures.

[0035] The method steps and data described in the present invention are only specific embodiments of the present invention, and are an overall description and illustration of the spirit of the present invention. Those skilled in the art to which the present invention belongs may also be aware of the various possibilities of variant or optional embodiments, and make various modifications, supplements, improvements or substitutions inspired by the spirit and principles of the present invention. It is understood that these modifications, supplements, improvements or substitutions are considered to be included in the present invention, and will not deviate from the spirit of the present invention or exceed the scope defined by the attached claims.

Claims

1. A sulphur-portland cement, characterized in that: include: Sulfosilicate clinker, gypsum and admixtures, in parts by mass, wherein 50-90 parts of sulfosilicate clinker, 4-25 parts of gypsum and 5-50 parts of admixtures; The mixed material is an aluminum-containing mixed material and / or an aluminum-free mixed material. The aluminum-containing mixed material is at least one of fly ash, slag powder, metakaolin, red mud, and calcined coal gangue; The non-aluminum mixed material is at least one of limestone powder, carbide slag, sandstone powder and shale powder.

2. A sulphur-portland cement according to claim 1, characterized in that: The mineral composition of the sulphoaluminate clinker is: 15-50wt.% of calcium sulphoaluminate, 5-50wt.% of calcium sulphoaluminate, 10-70wt.% of dicalcium silicate, 2-15wt.% of free gypsum, and 0-2wt.% of free lime.

3. A sulphur-portland cement according to claim 1, characterized in that: It also includes a performance adjustment component, which is 0-5 parts by weight.

4. A sulphur-portland cement according to claim 3, characterized in that: The performance adjustment component includes at least one of quicklime, magnesium oxide and an expander.

5. A sulphur-portland cement according to claim 1, characterized in that: The gypsum is a natural raw material or solid waste containing calcium sulfate.

6. A method for preparing the sulpho-Portland cement according to any one of claims 1 to 5, comprising: Grind the thiosilicate clinker to a 45 μm sieve residue of ≤25%, and fully mix the thiosilicate clinker with gypsum to obtain a mixture of thiosilicate clinker and gypsum; The sulpho-silicate clinker and gypsum mixture are then configured as a mixed material, and the mixture is fully mixed by a mixing device to prepare sulpho-silicate cement.

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