Gypsum-based non-calcined sulfoaluminate cement and method for its production

Abstract

The application belongs to the technical field of special cement, and relates to a gypsum-based calcination-free sulphoaluminate cement and a preparation method thereof. In order to solve the problems of high energy consumption and high pollution in calcining clinker for producing sulphoaluminate cement, and the problems of recycling and high-quality utilization of multiple solid wastes, the gypsum-based calcination-free sulphoaluminate cement comprises building gypsum, anhydrite, silica fume, ultra-fine fly ash, cement, carbide slag, zeolite powder, expanded perlite attached microbial powder, aluminum sulfate, melamine, borax, sodium citrate and polycarboxylic acid high-performance water reducing agent. Through reasonable matching of the melamine, the borax and the sodium citrate, effective nutrient components are provided for the microorganisms, the breeding and excretion of the microorganisms are promoted, and then the self-repairing property and the comprehensive performance of the calcination-free sulphoaluminate cement are improved. Through optimization combination of multiple-component solid waste powders, the normal hydration and strength growth of the calcination-free sulphoaluminate cement are realized by introducing the enhanced excitation components and the microorganisms.

Description

Technical Field

[0001] This invention belongs to the field of special cement technology and relates to a gypsum-based non-calcining sulfoaluminate cement and its preparation method. In particular, it relates to the application fields that can replace or partially replace traditional sulfoaluminate cement, and has advantages such as low carbon and environmental protection, ultra-low energy consumption, no calcination, multiple solid waste utilization, and high added value. Background Technology

[0002] Since the invention of aluminate cement in 1908, specialty cement has entered a period of rapid development, with numerous specialty cement varieties being invented and applied. In most developed countries, specialty cement accounts for 5% to 10% of total cement consumption. Research and production of specialty cement in my country began in the 1930s, and in the 1980s, sulfoaluminate cement was invented, marking another major innovation in the development of cement varieties in human history. After more than half a century of development, my country's specialty cement technology has reached the forefront of the world. Sulfoaluminate cement is characterized by rapid setting and hardening, early strength and high strength, concentrated heat release during hydration, ability to harden at low temperatures, good frost resistance and impermeability, as well as excellent corrosion resistance and low alkalinity. Furthermore, concrete prepared with this cement exhibits excellent resistance to carbonation, alkali-aggregate reaction, and shrinkage and creep, making it widely used in marine engineering, low-temperature construction, rapid construction, and antique-style architectural projects.

[0003] However, the production of sulfoaluminate cement is a high-energy-consuming and high-polluting industry, and its clinker calcination temperature is only about 100°C lower than that of silicate cement clinker. After research and development by experts and scholars, high-belite sulfoaluminate cement and other materials have been developed, and its clinker calcination temperature can only be reduced to about 1200°C.

[0004] Therefore, it is urgent to develop a non-calcined, low-energy-consumption sulfoaluminate cement. This invention is based on the fact that the main minerals of sulfoaluminate cement clinker are anhydrous calcium sulfoaluminate (C4A3S), dicalcium silicate (C2S), and iron phase, of which C4A3S accounts for 55% to 75%, C2S accounts for 8% to 37%, and iron phase accounts for about 3% to 10%. Gypsum is then added to form sulfoaluminate cement. Inspired by the chemical composition of sulfoaluminate cement, which contains about 40% gypsum before and after calcination, the non-calcined sulfoaluminate cement of this invention can solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of high energy consumption and high pollution in the production of calcined clinker of sulfoaluminate cement, as well as the problem of high-quality recycling of multiple solid wastes, and at the same time to achieve the mass production of gypsum-based multi-solid waste non-calcined sulfoaluminate cement, so as to meet the application scenarios of special cements and achieve the "dual carbon" goal.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] This invention provides a gypsum-based, non-calcined sulfoaluminate cement, comprising building gypsum, anhydrite, silica fume, ultrafine fly ash, cement, carbide slag, zeolite powder, expanded perlite-supported microbial powder, aluminum sulfate, melamine, borax, sodium citrate, and polycarboxylate superplasticizer. The mass percentages of each raw material component are as follows:

[0008] Building plaster: 25%–50%

[0009] Anhydrite: 10%–25%;

[0010] Silica fume: 0.5%–2%;

[0011] Ultrafine fly ash: 12%–20%;

[0012] Cement: 6%–10%;

[0013] Carbide slag: 2%–5%;

[0014] Zeolite powder: 5%–10%;

[0015] Expanded perlite loaded with microbial powder: 2%–7%;

[0016] Aluminum sulfate: 0.4%–1%;

[0017] Melamine: 0.2%–0.5%;

[0018] Borax: 0.2%–0.6%;

[0019] Sodium citrate: 0.01%–0.05%;

[0020] Polycarboxylate superplasticizer: 0.3%–0.8%.

[0021] Furthermore, the building gypsum is hemihydrate gypsum with a fineness controlled at 200 mesh. The hemihydrate gypsum is made by grinding and calcining natural dihydrate gypsum ore, or by calcining industrial by-products such as desulfurized gypsum and phosphogypsum, or by drying at 100°C.

[0022] Furthermore, the anhydrite is natural anhydrite ground into powder, or natural dihydrate gypsum powder or industrial by-product gypsum powder calcined to produce anhydrous gypsum.

[0023] Furthermore, the ultrafine fly ash is milled from circulating fluidized bed fly ash, and its specific surface area is controlled at 800 m². 2 / kg~1200m 2 / kg.

[0024] Furthermore, the cement is P·O42.5 cement or silicate cement.

[0025] Furthermore, the waste residue from the acetylene gas production at the calcium carbide slag chemical plant is dried and ground to obtain the product, which has a specific surface area greater than 300 m². 2 / kg.

[0026] Furthermore, the zeolite powder is obtained by grinding tailings, and its specific surface area is greater than 300 m². 2 / kg.

[0027] Furthermore, the aluminum sulfate is a 200-mesh powder.

[0028] This invention also provides a method for preparing gypsum-based non-calcined sulfoaluminate cement, comprising the following steps:

[0029] Building gypsum, anhydrite, silica fume, ultrafine fly ash, cement, carbide slag, zeolite powder, expanded perlite-supported microbial powder, aluminum sulfate, melamine, borax, sodium citrate, and polycarboxylate high-performance water-reducing agent are added to a powder mixer according to the mass percentage of each raw material component. Mixing for 5–7 minutes yields the gypsum-based non-calcined sulfoaluminate cement.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] (1) The non-calcined sulfoaluminate cement powder material of the present invention has the advantages of simple production, non-toxic and pollution-free; high compressive strength at all ages, no reduction in compressive strength in the later stage, good durability, ultra-low energy consumption, no calcination, no solid waste, and low cost.

[0032] (2) The traditional high-temperature calcined clinker production of special cement has been changed to non-calcined sulfoaluminate cement, achieving ultra-low energy consumption and solid waste utilization rate of about 95%.

[0033] (3) By rationally matching melamine, borax and sodium citrate, effective nutrient components are provided for microorganisms, which promotes the reproduction of microorganisms and the increase of excrement, thereby improving the self-healing and comprehensive performance of non-fired sulfoaluminate cement.

[0034] (4) By optimizing the combination of multi-component solid waste powder, and by introducing reinforcing and activating components and microorganisms, normal hydration and strength growth of non-fired sulfoaluminate cement were achieved.

[0035] (5) It has realized the production of gypsum-based multi-solid waste non-calcination sulfoaluminate cement to meet the application scenarios of special cement and achieve the "dual carbon" goal. Detailed Implementation

[0036] To further illustrate the technical solution of the present invention, the present invention will be further described below through embodiments.

[0037] A gypsum-based, non-calcinable sulfoaluminate cement comprises building gypsum, anhydrite, silica fume, ultrafine fly ash, cement, carbide slag, zeolite powder, expanded perlite-supported microbial powder, aluminum sulfate, melamine, borax, sodium citrate, and polycarboxylate superplasticizer. The mass percentages of each raw material component are as follows:

[0038] Building plaster: 25%–50%

[0039] Anhydrite: 10%–25%;

[0040] Silica fume: 0.5%–2%;

[0041] Ultrafine fly ash: 12%–20%;

[0042] Cement: 6%–10%;

[0043] Carbide slag: 2%–5%;

[0044] Zeolite powder: 5%–10%;

[0045] Expanded perlite loaded with microbial powder: 2%–7%;

[0046] Aluminum sulfate: 0.4%–1%;

[0047] Melamine: 0.2%–0.5%;

[0048] Borax: 0.2%–0.6%;

[0049] Sodium citrate: 0.01%–0.05%;

[0050] Polycarboxylate superplasticizer: 0.3%–0.8%.

[0051] Among them, the building gypsum is natural dihydrate gypsum ore powder that is ground and calcined into hemihydrate gypsum, or industrial by-products such as desulfurized gypsum and phosphogypsum that are calcined into hemihydrate gypsum. It can also be made by drying at 100℃. In this embodiment, desulfurized hemihydrate gypsum is selected, and its fineness is controlled at about 200 mesh.

[0052] Anhydrite is made by grinding natural anhydrite into powder, or by calcining natural dihydrate gypsum powder or industrial by-product gypsum powder into anhydrous gypsum. In this embodiment, natural anhydrite powder is selected, and its fineness is controlled at around 200 mesh.

[0053] The ultrafine fly ash is produced by grinding circulating fluidized bed fly ash, and its specific surface area is controlled at 800 m². 2 / kg~1200m 2 / kg.

[0054] The cement used is commercially available 42.5 grade ordinary Portland cement, but Portland cement can also be used instead. In this embodiment, P·O42.5 cement is selected.

[0055] The ultrafine fly ash is produced by grinding circulating fluidized bed fly ash, and its specific surface area is controlled at 800 m². 2 / kg~1200m 2 / kg.

[0056] Calcium carbide slag is a waste residue from the production of acetylene gas in chemical plants, which is dried and ground into fine powder. Its specific surface area is greater than 300 m². 2 / kg.

[0057] Zeolite powder is produced by grinding tailings, and its specific surface area is greater than 300 m². 2 / kg.

[0058] Expanded perlite-loaded microbial powder is developed and produced by Shanxi Shengke Microbial Building Materials Technology Co., Ltd. It is made by independently screening KJ series microorganisms and loading them onto expanded perlite powder of about 100 mesh, and then drying it at low temperature. The KJ series microorganisms have been deposited at the China General Microbiological Culture Collection Center, with accession number: CGMCC NO:15516.

[0059] Aluminum sulfate is industrial grade, made into powder of about 200 mesh, white crystals or slightly yellowish, containing 16 molecules of water of crystallization, and is easily soluble in water.

[0060] Melamine, borax, and sodium citrate are all industrial grade. Melamine acts as a reinforcing and toughening agent in the system, while borax and sodium citrate act as retarders. Other retarders can also be selected, such as boric acid, phosphates, and organic acid salts.

[0061] The polycarboxylate high-performance water-reducing agent is a commercially available standard powder with a water reduction rate of 26%.

[0062] The preparation method is to add the above raw materials to a zero-gravity mixer (or other powder mixer) in proportion and mix for 5 to 7 minutes to obtain the finished product.

[0063] Example 1

[0064] This embodiment of a gypsum-based, non-calcinable sulfoaluminate cement includes:

[0065] Building plaster: 25%;

[0066] Anhydrite: 25%;

[0067] Silica fume: 1.2%;

[0068] Ultrafine fly ash: 20%;

[0069] P·O42.5 cement: 10%;

[0070] Carbide slag: 2%;

[0071] Zeolite powder: 8%;

[0072] Expanded perlite loaded with microbial powder: 7%;

[0073] Aluminum sulfate: 1%;

[0074] Melamine: 0.29%;

[0075] Borax: 0.2%;

[0076] Sodium citrate: 0.01%;

[0077] Polycarboxylate superplasticizer: 0.3%.

[0078] Example 2

[0079] This embodiment of a gypsum-based, non-calcinable sulfoaluminate cement includes:

[0080] Building plaster: 28%;

[0081] Anhydrite: 22%;

[0082] Silica fume: 2%;

[0083] Ultrafine fly ash: 18%;

[0084] P·O42.5 cement: 7%;

[0085] Carbide slag: 5%;

[0086] Zeolite powder: 10%;

[0087] Expanded perlite loaded with microbial powder: 5.6%;

[0088] Aluminum sulfate: 0.8%;

[0089] Melamine: 0.5%;

[0090] Borax: 0.48%;

[0091] Sodium citrate: 0.02%;

[0092] Polycarboxylate superplasticizer: 0.6%.

[0093] Example 3

[0094] This embodiment of a gypsum-based, non-calcinable sulfoaluminate cement includes:

[0095] Building plaster: 42%;

[0096] Anhydrite: 18%;

[0097] Silica fume: 1%;

[0098] Ultrafine fly ash: 16%;

[0099] P·O42.5 cement: 6%;

[0100] Carbide slag: 4%;

[0101] Zeolite powder: 7%;

[0102] Expanded perlite loaded with microbial powder: 4.3%;

[0103] Aluminum sulfate: 0.6%;

[0104] Melamine: 0.2%;

[0105] Borax: 0.37%;

[0106] Sodium citrate: 0.03%;

[0107] Polycarboxylate superplasticizer: 0.5%.

[0108] Example 4

[0109] This embodiment of a gypsum-based, non-calcinable sulfoaluminate cement includes:

[0110] Building plaster: 45%;

[0111] Anhydrite: 14%;

[0112] Silica fume: 0.5%;

[0113] Ultrafine fly ash: 14%;

[0114] P·O42.5 cement: 10%;

[0115] Carbide slag: 5%;

[0116] Zeolite powder: 6%;

[0117] Expanded perlite loaded with microbial powder: 3.1%;

[0118] Aluminum sulfate: 0.9%;

[0119] Melamine: 0.4%;

[0120] Borax: 0.36%;

[0121] Sodium citrate: 0.04%;

[0122] Polycarboxylate superplasticizer: 0.7%.

[0123] Example 5

[0124] This embodiment of a gypsum-based, non-calcinable sulfoaluminate cement includes:

[0125] Building plaster: 50%;

[0126] Anhydrite: 10%;

[0127] Silica fume: 2%;

[0128] Ultrafine fly ash: 12%;

[0129] P·O42.5 cement: 9%;

[0130] Carbide slag: 5%;

[0131] Zeolite powder: 5%;

[0132] Expanded perlite loaded with microbial powder: 4.7%;

[0133] Aluminum sulfate: 0.4%;

[0134] Melamine: 0.45%;

[0135] Borax: 0.6%;

[0136] Sodium citrate: 0.05%;

[0137] Polycarboxylate superplasticizer: 0.8%.

[0138] The cement material is prepared according to the above-mentioned mass percentages and preparation method, thus obtaining the finished product. When using it, the water-cement ratio should be controlled between 0.27 and 0.30, and it should be stirred evenly.

[0139] According to GB20472-2006 "Sulfoaluminate Cement", the performance of the gypsum-based non-calcined sulfoaluminate cements prepared in Examples 1-5 was tested, and the test results are shown in the table below:

[0140] Table 1. Test results of Examples 1-5

[0141]

[0142]

[0143] Note: Setting time is a negotiable parameter.

[0144] As shown in Table 1, the gypsum-based non-calcined sulfoaluminate cement prepared by the present invention has excellent performance test results in terms of free expansion rate, compressive strength and flexural strength, all of which are higher than the standard. Among them, Example 2 is the preferred formulation.

Claims

1. A gypsum-based, non-calcinable sulfoaluminate cement, characterized in that, The ingredients include building gypsum, anhydrite, silica fume, ultrafine fly ash, cement, carbide slag, zeolite powder, expanded perlite-supported microbial powder, aluminum sulfate, melamine, borax, sodium citrate, and polycarboxylate superplasticizer. The mass percentages of each raw material component are as follows: Building plaster: 25%~50% Anhydrite: 10%~25%; Silica fume: 0.5%~2%; Ultrafine fly ash: 12%~20%; Cement: 6%~10%; Calcium carbide slag: 2%~5%; Zeolite powder: 5%~10%; Expanded perlite loaded with microbial powder: 2%~7%; Aluminum sulfate: 0.4%~1%; Melamine: 0.2%~0.5%; Borax: 0.2%~0.6%; Sodium citrate: 0.01%~0.05%; Polycarboxylate superplasticizer: 0.3%~0.8%; The ultrafine fly ash is produced by grinding circulating fluidized bed fly ash, and its specific surface area is controlled at 800 m². 2 / kg~1200m 2 / kg; the zeolite powder is obtained by grinding tailings, and its specific surface area is greater than 300m². 2 / kg.

2. The gypsum-based non-calcining sulfoaluminate cement according to claim 1, characterized in that, The building gypsum is hemihydrate gypsum with a fineness controlled at 200 mesh. The hemihydrate gypsum is made by grinding and calcining natural dihydrate gypsum ore, or by calcining industrial by-products such as desulfurized gypsum and phosphogypsum.

3. The gypsum-based non-calcining sulfoaluminate cement according to claim 1, characterized in that, The anhydrite is made from natural anhydrite powder, or from natural dihydrate gypsum powder or industrial by-product gypsum powder calcined to produce anhydrous gypsum.

4. The gypsum-based non-calcining sulfoaluminate cement according to claim 1, characterized in that, The cement is P. ․ O42.5 cement or silicate cement.

5. The gypsum-based non-calcining sulfoaluminate cement according to claim 1, characterized in that, The calcium carbide slag is a waste residue from the production of acetylene gas in chemical plants, which is dried and ground to obtain it, and its specific surface area is greater than 300 m². 2 / kg.

6. The gypsum-based non-calcining sulfoaluminate cement according to claim 1, characterized in that, The aluminum sulfate is a 200-mesh powder.

7. A method for preparing gypsum-based non-calcined sulfoaluminate cement according to any one of claims 1-6, characterized in that, Includes the following steps: Building gypsum, anhydrite, silica fume, ultrafine fly ash, cement, carbide slag, zeolite powder, expanded perlite-loaded microbial powder, aluminum sulfate, melamine, borax, sodium citrate, and polycarboxylate high-performance water-reducing agent are added to a powder mixer according to the mass percentage of each raw material component. After mixing for 5-7 minutes, the gypsum-based non-calcined sulfoaluminate cement can be obtained.

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