阅读说明：本技术 硫铝酸盐-镁铝尖晶石胶凝材料及制备方法、系统和应用 (Sulphoaluminate-magnesium aluminate spinel cementing material, preparation method, system and application ) 是由 任常在 华栋梁 李欢 王文龙 单光和 陈雷 于 2021-09-29 设计创作，主要内容包括：本发明属于资源循环利用和先进无机非金属材料技术领域,具体涉及硫铝酸盐-镁铝尖晶石胶凝材料及制备方法、系统和应用。主要由硫铝酸四钙、硅酸二钙和镁铝尖晶石组成,镁铝尖晶石的质量分数不低于20％。采用富氧煅烧对二次铝灰进行脱氮、脱盐、脱氟处理获得煅烧铝灰,将煅烧铝灰与脱硫镁渣、白云石尾矿、电石渣混合后煅烧,即得；所述富氧煅烧为外热式的加热方式。本发明提供的胶凝材料兼具有快硬、早强的水泥功能,同时在大体积浇筑中具有抗热震性,在高温下无裂纹产生。同时本发明能够实现电石渣、镁法脱硫副产物、二次铝灰向高值化硫铝酸盐-镁铝尖晶石特种胶凝材料转化,大大降低特种胶凝材料的生产成本。(The invention belongs to the technical field of resource recycling and advanced inorganic nonmetallic materials, and particularly relates to a sulphoaluminate-magnesium aluminate spinel cementing material, and a preparation method, a system and application thereof. Mainly comprises tetracalcium sulphoaluminate, dicalcium silicate and magnesium aluminate spinel, and the mass fraction of the magnesium aluminate spinel is not less than 20%. Performing denitrification, desalination and defluorination treatment on the secondary aluminum ash by oxygen-enriched calcination to obtain calcined aluminum ash, and mixing and calcining the calcined aluminum ash, the desulfurized magnesium slag, the dolomite tailings and the carbide slag to obtain the product; the oxygen-enriched calcination adopts an external heating type heating mode. The cementing material provided by the invention has the functions of quick hardening and early strength cement, and simultaneously has thermal shock resistance in large-volume pouring, and no crack is generated at high temperature. Meanwhile, the invention can realize the conversion of carbide slag, magnesium desulphurization by-products and secondary aluminum ash to high-value sulphoaluminate-magnesium aluminate spinel special cementing materials, thereby greatly reducing the production cost of the special cementing materials.)

1. A sulphoaluminate-magnesia-alumina spinel cementing material is characterized by mainly comprising tetracalcium sulphoaluminate, dicalcium silicate and magnesia-alumina spinel, wherein the mass fraction of the magnesia-alumina spinel is not less than 20%.

2. The sulphoaluminate-magnesia-alumina spinel gel material of claim 1, wherein the mass fraction of the magnesia-alumina spinel is 20-40%; preferably 20-30%;

or the mass ratio of the mineral phases is C₄A₃$：MgAl₂O₄：C₂S: magnesium oxide: alumina: 55-65% of forskolite: 20-30: 0-5: 0-5: 0 to 5.

3. The sulphoaluminate-magnesia-alumina spinel cement as claimed in claim 1, wherein the specific surface area is 300-350 m²/g；

Or the particle size is below 380 meshes and occupies 95% or more.

4. A preparation method of the sulphoaluminate-magnesia-alumina spinel cementing material according to any one of claims 1 to 3, which is characterized in that oxygen-enriched calcination is adopted to carry out denitrification, desalination and defluorination treatment on secondary aluminum ash to obtain calcined aluminum ash, and the calcined aluminum ash is mixed with desulfurized magnesium slag, dolomite tailings and carbide slag and then calcined to obtain the sulphoaluminate-magnesia-alumina spinel cementing material; the oxygen-enriched calcination adopts an external heating type heating mode.

5. The preparation method of the sulphoaluminate-magnesia-alumina spinel cementing material of claim 4, which is characterized in that the mass ratio of calcined aluminum ash, desulfurized magnesium slag, dolomite tailings and carbide slag is 85-100: 45-65: 35-45: 20-35;

or the temperature of the oxygen-enriched calcination is 1000-1100 ℃, preferably 1050 ℃, and the oxygen content in the flue gas is 20-25%;

or, the content of alumina in the calcined aluminum ash is more than 85 percent;

or the salt content of the calcined aluminum ash is lower than 2 percent;

or the water content of the calcined aluminum ash is lower than 2 percent after being mixed with the desulfurized magnesium slag, the dolomite tailings and the carbide slag.

6. The method for preparing sulphoaluminate-magnesia-alumina spinel cement as claimed in claim 4, wherein the desulfurized magnesium slag, dolomite tailings and carbide slag are dried and then calcined with calcined aluminum ash;

preferably, the flue gas after oxygen-enriched calcination is used for drying desulfurized magnesium slag, dolomite tailings and carbide slag;

or, the calcined aluminum ash is mixed with the desulfurized magnesium slag, the dolomite tailings and the carbide slag, and then the correcting material is added.

7. A system for preparing the sulphoaluminate-magnesium aluminate spinel cementitious material of any one of claims 1 to 3, comprising:

the external heating rotary kiln is used for carrying out oxygen-enriched calcination on the secondary aluminum ash to realize the denitrification, defluorination and desalination treatment of the secondary aluminum ash;

the cement rotary kiln is used for calcining calcined aluminum ash, desulfurized magnesium slag, dolomite tailings and carbide slag after oxygen-enriched calcination to prepare the sulphoaluminate-magnesia-alumina spinel cementing material.

8. The sulphoaluminate-magnalium spinel cementitious material system of claim 7, including a dryer for drying the desulphurized magnesium slag, dolomite tailings and carbide slag, wherein the desulphurized magnesium slag, dolomite tailings and carbide slag are dried and then delivered to the cement rotary kiln.

9. The system of sulphoaluminate-magnesia-alumina spinel cement of claim 8, wherein flue gas generated from a cement rotary kiln is used as a heat source for a dryer;

or the waste heat generated by the external heating rotary kiln is used as a heat source of the dryer;

or, the flue gas generated by the external heating type rotary kiln is conveyed to the condenser for condensation and desalination, and then the flue gas subjected to desalination is used as a heat source of the dryer;

or the crusher is used for crushing the desulfurized magnesium slag, the dolomite tailings and the carbide slag, and then conveying the crushed desulfurized magnesium slag, dolomite tailings and carbide slag to the dryer.

10. Use of the sulphoaluminate-magnesium aluminate spinel cementitious material according to any one of claims 1 to 3 in large-volume casting construction.

Technical Field

The invention belongs to the technical field of resource recycling and advanced inorganic nonmetallic materials, and particularly relates to a sulphoaluminate-magnesium aluminate spinel cementing material, and a preparation method, a system and application thereof.

Background

The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.

The difficult problem of resource utilization of various magnesium-containing waste residues generated in the whole process of mining, smelting and utilizing magnesium resources such as dolomite tailings, magnesite tailings, magnesium slag, magnesium method desulphurization byproducts and the like with large cracking amount, wide area and high harm is an important task for promoting green development of magnesium resources and ecological civilization construction. The various solid wastes generated in the magnesium industry chain are difficult to completely transform into resources, and the solid wastes have bottlenecks in two aspects of the solid wastes and the technical path: (1) the solid waste has various types, mixed components, poor properties, high cost for disposal and utilization and poor performance of derived products, so the attribute and value of the solid waste are not broken through; (2) the conventional solid waste recycling path is mostly limited by a single solid waste value-seeking excavation way, has strong technical constraint, and urgently needs to break through a solid waste recycling process technology with fundamental innovation.

The magnesium-containing waste residue is used for preparing the wide-range component special cementing material with low carbon, or is one of the approaches for high-value, large-scale and harmless utilization. The special cementing material is taken as a 'key' material in the field of key engineering, wherein the special cementing material represented by sulfur (iron) aluminate (SAC/FAC), aluminate (CA) and Magnesium Phosphate (MPCs) is regarded as a preferred material for major special engineering due to the excellent characteristics of early strength, high temperature resistance, corrosion resistance and the like. However, the traditional SAC/FAC, CA and MPCs materials have strict requirements on the grade of raw materials bauxite and magnesite, and meanwhile, the energy consumption and CO are high in the preparation process of the magnesium phosphate cementing material₂The discharge amount is high, and the problems limit the large-scale application of the traditional special cementing material.

In addition, the inventor researches and discovers that the existing sulphoaluminate cementing material hydration product is mainly calcite, and the mineral is decomposed under the condition of 100-120 ℃, so that heat is difficult to release in the hydration heat release process of sulphoaluminate clinker in the large-volume pouring process, the heat is intensively released in a pouring body, the temperature of the pouring body is increased, the decomposition temperature of the calcite is easy to reach, and the sulphoaluminate special cementing material is difficult to pour in a large volume.

Disclosure of Invention

In order to solve the defects of the prior art, the invention aims to provide a sulphoaluminate-magnesia-alumina spinel cementing material, a preparation method, a system and application thereof. Meanwhile, the invention can realize the conversion of carbide slag, magnesium desulphurization by-products and secondary aluminum ash to high-value sulphoaluminate-magnesium aluminate spinel special cementing materials, thereby greatly reducing the production cost of the special cementing materials.

In order to achieve the purpose, the technical scheme of the invention is as follows:

on one hand, the sulphoaluminate-magnesium aluminate spinel gel material mainly comprises tetracalcium sulphoaluminate, dicalcium silicate and magnesium aluminate spinel, and the mass fraction of the magnesium aluminate spinel is not less than 20%.

In order to solve the problem that the special sulphoaluminate cementing material is difficult to pour in a large volume, the magnesium aluminate spinel is compounded with tetracalcium sulphoaluminate and dicalcium silicate, and the magnesium aluminate spinel has the advantages of high thermal shock resistance, high temperature resistance, low thermal deformation rate and the like, so that the special sulphoaluminate-magnesium aluminate spinel cementing material system has the functions of quick hardening and early strength cement. Meanwhile, experiments show that when the mass fraction of the magnesia-alumina spinel in the cementing material is not higher than 10%, the formed gel material has no thermal shock resistance in large-volume pouring, and when the mass fraction of the magnesia-alumina spinel in the cementing material is not lower than 20%, the gel material has thermal shock resistance in large-volume pouring, and no crack is generated at high temperature.

The sulphoaluminate-magnesium aluminate spinel cementing material can be obtained by mixing sulphoaluminate cement clinker with magnesium aluminate spinel, but the sulphoaluminate cement clinker and the magnesium aluminate spinel need to be mixed very uniformly to achieve the corresponding effect. If the mixing is not uniform, performance is degraded.

In addition, the main method for producing the magnesia-alumina spinel and sulphoaluminate cementing material in the prior art comprises the following steps: the magnesia-alumina spinel is mainly prepared by a traditional solid phase method, a gel solid phase method, a precipitation method, a sol-gel method, a hydrothermal synthesis method, a combustion synthesis method and the like, wherein the prior art adopts the most two-section calcination process, namely, the magnesia and the alumina with higher purity are prepared by two-time calcination processes, the preparation process of the two-section high-temperature calcination (1700 ℃) has higher energy consumption and larger usage amount of high-grade natural resources, and more CO is released by calcining magnesite at the same time₂. The production of the sulphoaluminate gelled material is mainly realized in a high-temperature calcination rotary kiln, the existing production mode is mainly to prepare the sulphoaluminate gelled material by mixing and proportioning limestone, bauxite and natural gypsum ore and calcining the mixture at high temperature, and in order to reduce a large amount of CO discharged in the calcination industry₂Other calcium mineral resources without calcium carbonate are generally used as substitutes of limestone minerals for raw material matching to prepare the limestone mineralAnd mixing the sulphoaluminate cementing material with the fly ash with low calorific value and the volcanic ash material in different proportions to form the sulphoaluminate cementing material with low calorific value. If the prior art is required to utilize natural resources to produce the magnesia-alumina spinel and the sulphoaluminate gelled material respectively, the economic benefit brought by the prepared magnesia-alumina spinel or sulphoaluminate gelled material is difficult to maintain higher added value, meanwhile, the environmental benefit is not obvious, and the operation cost is higher.

In addition, according to the research and understanding of the inventor, a technology for preparing the magnesia-alumina spinel by adopting a hydration method of aluminum ash and bischofite also exists at present, however, the technology needs to add a new chemical reagent, the preparation process is complex, and the operation cost is high.

In order to reduce the cost, on the other hand, the preparation method of the sulphoaluminate-magnesia-alumina spinel cementing material comprises the steps of carrying out denitrification, desalination and defluorination treatment on secondary aluminum ash by oxygen-enriched calcination to obtain calcined aluminum ash, mixing the calcined aluminum ash with desulfurized magnesium slag, dolomite tailings and carbide slag, and then calcining to obtain the sulphoaluminate-magnesia-alumina spinel cementing material; the oxygen-enriched calcination adopts an external heating type heating mode.

The secondary aluminum ash is a dangerous waste and contains a large amount of toxic and harmful substances such as fluoride, aluminum carbide, aluminum nitride and the like. When the secondary aluminum ash is used for manufacturing a special building material, the overflow of heavy metals, villiaumite, aluminum nitride and chloride salt to ammonia gas in the production process and the influence on the durability of a final product are mainly considered, the ammonia gas is easily generated when the aluminum nitride in the aluminum ash meets water, and the fluoride and the chloride in the aluminum ash are also mixed into the raw materials, so that the Cl in the final product exceeds the national standard, and meanwhile, the clinker sintering temperature is easily reduced due to the mixing of sodium fluoride and calcium fluoride, the industrial control is difficult, and the reduction of the content of the magnesium aluminate spinel mineral phase is also caused. Therefore, the secondary aluminum ash is subjected to denitrification, desalination and defluorination by oxygen-enriched calcination, the problems can be solved, and particularly, the aluminum nitride in the secondary aluminum ash is favorable for oxidation reaction through oxygen-enriched calcination, so that the aluminum nitride can be mixed with desulfurized magnesium slag, dolomite tailings and carbide slag and then calcined to prepare the sulphoaluminate-magnesia-alumina spinel gelled material.

The invention can simultaneously form the raw materials into the gel material mainly comprising tetracalcium sulphoaluminate, dicalcium silicate and magnesium aluminate spinel by one-time calcination, the calcination temperature is only 1200-1300 ℃, and the energy consumption is reduced.

If the internal heating type heating method is adopted, the oxygen-enriched calcination treatment of the secondary aluminum ash is difficult to realize.

In a third aspect, a system for preparing the above-described sulphoaluminate-magnesium aluminate spinel cementitious material comprises:

the external heating rotary kiln is used for carrying out oxygen-enriched calcination on the secondary aluminum ash to realize the denitrification, defluorination and desalination treatment of the secondary aluminum ash;

the cement rotary kiln is used for calcining calcined aluminum ash, desulfurized magnesium slag, dolomite tailings and carbide slag after oxygen-enriched calcination to prepare the sulphoaluminate-magnesia-alumina spinel cementing material.

In a fourth aspect, the sulphoaluminate-magnesia-alumina spinel cementing material is applied to large-volume pouring construction.

One or more technical schemes of the invention have the following beneficial effects:

1. the magnesium aluminate spinel mineral is introduced into the special sulphoaluminate cementing material system, and the magnesium aluminate spinel has the advantages of high thermal shock resistance, high temperature resistance, low thermal deformation rate and the like, so that the special sulphoaluminate-magnesium aluminate spinel cementing material system has the functions of quick hardening and early strength cement, has thermal shock resistance in large-volume pouring and does not generate cracks at high temperature.

2. The preparation method can prepare the high-temperature-resistant sulphoaluminate-magnesia-alumina spinel cementing material by using a large amount of dolomite tailings, desulfurized magnesium slag, secondary aluminum ash and carbide slag, not only can solve the technical problem of high-temperature spalling caused by difficult large-scale pouring of the traditional sulphoaluminate cementing material, but also uses a large amount of industrial solid wastes containing Mg, Ca, Si, S and the like, reduces the release of carbon dioxide caused by energy consumption in high-temperature calcination, and reduces the generation of greenhouse effect.

3. The sulphoaluminate-magnesia-alumina spinel high-temperature resistant inorganic gelled material formed by the preparation method of the invention consists of calcium, sulfur, aluminum, magnesium, silicon and the like, and the desulphurized magnesium slag is decomposed at high temperatureSO produced₂Ca (OH) of carbide slag in gas raw material₂After solid-phase reaction to produce CaSO₄Further CaO and Al are bonded₂O₃Combine to generate 3 CaO.3Al₂O₃·CaSO₄The magnesium oxide generated by pyrolysis and calcined aluminum ash are further calcined to generate the magnesia-alumina spinel, the prepared magnesia-alumina spinel high-temperature resistant material has excellent thermal shock resistance and corrosion resistance, and the performance of the prepared sulphoaluminate-magnesia-alumina spinel high-temperature resistant cementing material is not low while the additional value of solid waste products is effectively improved.

4. The invention utilizes secondary aluminum ash as a main raw material, and carries out external combustion oxygen-enriched calcination denitrification, defluorination and desalination pretreatment, and the secondary aluminum ash is directly subjected to raw material matching, calcination and other procedures with the dried desulfurized magnesium slag, dolomite tailings and carbide slag to obtain the sulphoaluminate-magnesia-alumina spinel cementing material, so that the development of the dolomite tailings, carbide slag, desulfurized magnesium slag and secondary aluminum ash to harmless, large-scale and resource paths can be realized.

5. The invention comprehensively utilizes dolomite tailings, carbide slag, desulfurized magnesium slag and secondary aluminum ash to produce sulphoaluminate-magnesia-alumina spinel gelled material, the raw materials for preparing the special gelled material mainly come from the tailings after dolomite mining, waste residue carbide slag generated by acetylene gas plants, desulfurized magnesium slag generated by power plants and secondary aluminum ash generated by electrolytic aluminum plants, the raw materials can be wastes generated in mining, electric power, metallurgy and chemical industries, and the sources of the raw materials are wide. The method can utilize industrial solid wastes and hazardous wastes in a large scale, can prepare the sulphoaluminate-magnesia-alumina spinel gelled material, has the characteristics of high temperature resistance, good thermal shock resistance and high-temperature strength of a hydration product, can be applied to high-temperature industries such as nuclear waste solid seal, self-heating heat source seal and the like, and can form a high-temperature solid sulfur phase 3 CaO.3Al when producing the sulphoaluminate-magnesia-alumina spinel gelled material₂O₃·CaSO₄Can absorb the S element in the magnesium sulfate and magnesium sulfite minerals which are easy to decompose at low temperature so as to meet the requirement of high-temperature sulfur fixation phase, and can be applied to the industries of flue gas sulfur fixation and the like.

6. The preparation method of the invention and the prior dolomiteThe comprehensive utilization modes of tailings, carbide slag, desulfurized magnesium slag and aluminum ash are different, the prepared sulphoaluminate-magnesia-alumina spinel special cementing material belongs to a high-temperature resistant inorganic cementing material, the mineral components of the material are different from those of the conventional calcium aluminate special cementing material, and the material is 3 CaO.3Al 2O 3.CaSO₄、MgAl₂O₄、2CaO·SiO₂Is a main mineral phase and contains a small amount of magadiite Ca₃MgSi₂O₈Free MgO or Al₂O₃The magnesium sulfate is a special inorganic material with high temperature resistance and corrosion resistance, and can fix S in magnesium sulfate and magnesium sulfite.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 is a process flow diagram of example 1 of the present invention;

FIG. 2 is an XRD of a sulphoaluminate-magnesium aluminate spinel gel material prepared in example 1 of the present invention;

FIG. 3 is an XRD of a thioaluminate-magnesia alumina spinel gel material prepared in example 2 of the present invention;

FIG. 4 is a picture of a sulphoaluminate-magnesium aluminate spinel gel material prepared by the example of the invention before and after 150 ℃ treatment.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

The oxygen-enriched calcination refers to a calcination treatment mode with the oxygen content larger than that in air, and the oxygen-enriched calcination refers to a calcination treatment mode with the oxygen volume content higher than 21% (obtained by mixing air and oxygen), wherein the oxygen content in the treated flue gas is not less than 19%.

In view of the difficulty in large-volume pouring of the special sulphoaluminate cementing material, the invention provides the sulphoaluminate-magnesium aluminate spinel cementing material, and a preparation method, a system and application thereof.

In one exemplary embodiment of the present invention, a sulphoaluminate-magnesium aluminate spinel gel material is provided, which mainly comprises tetracalcium sulphoaluminate, dicalcium silicate and magnesium aluminate spinel, wherein the mass fraction of the magnesium aluminate spinel is not less than 20%.

The sulphoaluminate-magnesia-alumina spinel cementing material provided by the invention has thermal shock resistance in large-volume pouring, and no crack is generated at high temperature (150 ℃).

The mass fraction of the magnesium aluminate spinel refers to the ratio of the mass of the magnesium aluminate spinel to the total mass of the gel material.

In some examples of this embodiment, the magnesium aluminate spinel is 20 to 40% by mass. Preferably 20 to 30%.

In some examples of this embodiment, the mass ratio of mineral phases is C₄A₃$：MgAl₂O₄：C₂S: magnesium oxide: alumina: MgSi Cailite (Ca)₃MgSi₂O₈)＝55～65：20～30：0～5：0～5：0～5。

In some examples of this embodiment, the specific surface area is 300 to 350m²/g。

In some examples of this embodiment, the particle size is 95% or more of the size below 380 mesh.

The invention also provides a preparation method of the sulphoaluminate-magnesia-alumina spinel cementing material, which comprises the steps of carrying out denitrification, desalination and defluorination treatment on secondary aluminum ash by oxygen-enriched calcination to obtain calcined aluminum ash, mixing the calcined aluminum ash with desulfurized magnesium slag, dolomite tailings and carbide slag, and then calcining the mixture to obtain the sulphoaluminate-magnesia-alumina spinel cementing material; the oxygen-enriched calcination adopts an external heating type heating mode.

The invention adopts oxygen-enriched calcination to carry out denitrification, desalination and defluorination treatment on the secondary aluminum ash, can prevent ammonia gas from being generated, and simultaneously avoids doping fluoride and chloride, thereby forming the sulphoaluminate-magnesia-alumina spinel cementing material.

The main component of the carbide slag is Ca (OH)₂The decomposition temperature is 500-600 ℃, and the CaO is decomposed. The desulfurized magnesium slag mainly comprises magnesium sulfite and magnesium sulfate, wherein the decomposition temperature of the magnesium sulfite is 430-550 ℃, the magnesium sulfite is decomposed into MgO and sulfur dioxide, and the magnesium sulfate is decomposed at 900-1060 ℃, SO that the SO generated by decomposing the desulfurized magnesium slag after the raw materials are calcined₂Can continue to react with Ca (OH)₂Reacts with CaO to generate an intermediate sulfur-fixing product CaSO₄。

When the calcined aluminum ash is mixed with the desulfurized magnesium slag, the dolomite tailings and the carbide slag and then calcined, the intermediate products CaO and Al are generated along with the increase of the calcination temperature₂O₃And CaSO₄Solid-phase reaction to generate 3 CaO.3Al₂O₃·CaSO₄At the same time, Al₂O₃The solid-phase reaction of the MgAl and MgO to generate MgAl₂O₄Powder of CaO and SiO₂Formation of Ca₂SiO₄Minerals and the whole clinker system mainly consists of 3 CaO.3Al₂O₃·CaSO₄MgAl₂O₄And Ca₂SiO₄And (4) forming.

The method of the invention can ensure the high-performance sulphoaluminate cementing material obtained by calcination, and can also obtain the magnesia-alumina spinel high-temperature resistant material, the magnesia-alumina spinel high-temperature resistant material is prepared by excessive alumina, no MgO exists in clinker, and CaO & Al exists₂O₃The mineral phase does not contain unstable mineral phase MgO, the coordination of the components meets the requirement that the hydration product of the sulphoaluminate-magnesium aluminate spinel special cementing material can be above 150 ℃ and the strength is not obviously shrunk, and the harmful components such as aluminum nitride, sodium fluoride, sodium chloride and the like in the sulfur and aluminum ash of the desulfurized magnesium slag can be harmlessly released and recycled, thereby realizing the sulphoaluminate cementing material and the sulphoaluminate spinel special cementing materialThe one-step reaction of the mixed special gel material of the magnesium aluminate spinel powder.

The desulfurized magnesium slag is used for replacing magnesia, the secondary aluminum ash is used for replacing bauxite, the carbide slag is used for replacing limestone, and the desulfurized gypsum is used for replacing natural gypsum, however, the raw materials do not contain CaO, MgO and Al which can be directly used₂O₃And CaSO₄The components can be directly proportioned and calcined to generate 3 CaO.3Al₂O₃·CaSO₄、MgAl₂O₄It is necessary that the mineral is formed after the formation of a specific secondary product. MgSO in desulfurized magnesium slag₃、MgSO₄Can be decomposed into MgO and SO at 430-550 ℃ and 900-1060 ℃ respectively₂. At the same time, Ca (OH) in the carbide slag₂Can absorb SO under the condition of low temperature and oxygen enrichment₂Formation of CaSO₄Or continuously absorbing SO after CaO is formed by pyrolysis₂Formation of CaSO₄(ii) a The secondary aluminum ash is subjected to external combustion oxygen-enriched denitrification, defluorination and desalination to mainly generate Al₂O₃And elemental aluminum; in this case, the method already has the step of forming 3 CaO.3Al₂O₃·CaSO₄、MgAl₂O₄、Ca₂SiO₄CaO, MgO, SiO required for mineral formation₂、Al₂O₃And CaSO₄. The calcination temperature is required to be specifically set in the decomposition region and the calcination region, and SO₂In a fixed setting, if the setting is inaccurate, intermediate products MgO and Al are difficult to form₂O₃、CaO、CaSO₄Therefore, the main mineral of the solid wastes containing aluminum nitride, fluoride, salt and the like, such as desulfurized magnesium slag, secondary aluminum ash, dolomite tailings, carbide slag and the like, is 3 CaO.3Al₂O₃·CaSO₄And MgAl₂O₄When the special high-temperature-resistant cementing material is used, a large amount of sulfur dioxide generated by the desulfurized magnesium slag is fixed at high temperature, and the problem that the sulphoaluminate cementing material is difficult to pour and apply in large volume in a high-temperature environment is solved urgently.

The inventor discovers that when the mass ratio of calcined aluminum ash to desulfurized magnesium slag to dolomite tailings to carbide slag is 85-100: 45-65: 35 ℃45:20～35，3CaO·3Al₂O₃·CaSO₄And MgAl₂O₄The main temperature range of the stable forming temperature is 1200-1350 ℃, the main temperature range of the secondary aluminum ash for denitrification, defluorination and desalination is 600-1100 ℃, when the calcining temperature of the raw material is 1200-1350 ℃, the raw material is kept warm for 25-35 min, natural resources such as magnesite, bauxite, gypsum and the like can be directly replaced by desulfurized magnesium slag, aluminum ash, dolomite tailings and carbide slag to directly prepare the high-temperature-resistant type sulphoaluminate-magnesium aluminate spinel special cementing material, so that a large amount of industrial solid waste and hazardous waste are consumed, and the energy consumption is reduced. The mass ratio of the calcined aluminum ash to the desulfurized magnesium slag to the dolomite tailings to the carbide slag is preferably 97:59:40:25, and the special high-temperature-resistant gel material with better performance, namely the sulphoaluminate-magnesia-alumina spinel, can be obtained under the condition of the mass ratio.

In the process of calcining the raw materials, because the secondary aluminum ash, the desulfurized magnesium slag, the dolomite tailings and the carbide slag are used as the raw materials, alumina and magnesia for producing bauxite, magnesite, limestone ore and gypsum are not used as the raw materials, excessive carbon dioxide and sulfur dioxide are not generated, and in addition, 3CaO 3Al in the sulphoaluminate-magnesium aluminate spinel material is not decomposed₂O₃·CaSO₄The content of mineral phase is 40-60%, MgAl₂O₄Mineral phase content of 20-30%, Ca₂SiO₄The mineral phase content is 5-10%, and in the production process, a large amount of calcium hydroxide in the carbide slag can be used for absorbing, sulfur dioxide gas generated by decomposing the desulfurized magnesium slag at high temperature is formed, and an intermediate product CaSO is formed₄And further with CaO, MgO, Al₂O₃Solid-phase reaction to generate 3CaO 3Al₂O₃·CaSO₄Minerals and MgAl₂O₄The mineral phase high-temperature resistant special cementing material realizes the purpose of preparing the sulphoaluminate-magnesia-alumina spinel high-temperature resistant special cementing material by utilizing a large amount of desulfurized magnesium slag, secondary aluminum ash, dolomite tailings and carbide slag, and makes great contribution to digesting the stockpiled desulfurized magnesium slag, tailings and secondary aluminum ash.

In some embodiments of the embodiment, the temperature of the oxygen-enriched calcination is 1000-1100 ℃, preferably 1050 ℃, and the oxygen content in the flue gas is 20-25%. At this temperature and oxygen content, the secondary aluminum ash is promoted to convert all aluminum nitride into aluminum oxide, and defluorination and desalination are facilitated.

In some examples of this embodiment, the calcined aluminum ash has an alumina content of greater than 85%.

In some examples of this embodiment, the calcined aluminum ash has a salt content of less than 2%.

In some examples of this embodiment, the calcined aluminum ash is mixed with the desulfurized magnesium slag, the dolomite tailings, and the carbide slag to have a moisture content of less than 2%.

In some examples of this embodiment, the desulfurized magnesium slag, dolomite tailings, and carbide slag are dried and then calcined with calcined aluminum ash.

In one or more embodiments, the flue gas after oxygen-enriched calcination is used for drying desulfurized magnesium slag, dolomite tailings and carbide slag.

In order to ensure that the mass fraction of the magnesia-alumina spinel in the sulphoaluminate-magnesia-alumina spinel cementitious material formed after calcination is not less than 20%, in some examples of the embodiment, the calcined aluminum ash is mixed with the desulfurized magnesium slag, the dolomite tailings and the carbide slag, and then the correcting material is added. The purpose of adding the correction material is to adjust the mass fraction of the magnesium aluminate spinel in the sulphoaluminate-magnesium aluminate spinel gelled material formed after calcination. The correcting material is calcined aluminum ash, desulfurized magnesium slag and/or carbide slag.

In a third embodiment of the present invention, there is provided a system for preparing the above-mentioned sulphoaluminate-magnesium aluminate spinel cement, comprising:

the external heating rotary kiln is used for carrying out oxygen-enriched calcination on the secondary aluminum ash to realize the denitrification, defluorination and desalination treatment of the secondary aluminum ash;

the cement rotary kiln is used for calcining calcined aluminum ash, desulfurized magnesium slag, dolomite tailings and carbide slag after oxygen-enriched calcination to prepare the sulphoaluminate-magnesia-alumina spinel cementing material.

The system can realize the high-temperature-resistant type sulphoaluminate-magnesia-alumina spinel special cementing material by utilizing secondary aluminum ash, desulfurized magnesium slag, dolomite tailings and carbide slag, thereby realizing the treatment of solid waste and hazardous waste, preparing the high-temperature-resistant type special cementing material and simultaneously reducing the production cost of raw materials.

Some examples of this embodiment include a dryer for drying the desulfurized magnesium slag, the dolomite tailings, and the carbide slag, and conveying the desulfurized magnesium slag, the dolomite tailings, and the carbide slag after drying to the rotary cement kiln.

In one or more embodiments, flue gas generated by the rotary cement kiln is used as a heat source for the dryer. The waste heat recycling is realized, the heat required by calcination can be effectively saved, and the energy is saved.

In one or more embodiments, waste heat generated by the external heat type rotary kiln is used as a heat source of the dryer. The waste heat recycling is realized, the heat required by calcination can be effectively saved, and the energy is saved.

In one or more embodiments, the flue gas generated by the external heating type rotary kiln is conveyed to the condenser to be condensed and desalted, and then the desalted flue gas is used as a heat source of the dryer.

In one or more embodiments, the system comprises a crusher, which is used for crushing the desulfurized magnesium slag, the dolomite tailings and the carbide slag, and then conveying the crushed desulfurized magnesium slag, dolomite tailings and carbide slag to a dryer.

In a fourth embodiment of the invention, the sulphoaluminate-magnesium aluminate spinel cementing material is applied to large-volume pouring construction.

In order to make the technical solutions of the present invention more clearly understood by those skilled in the art, the technical solutions of the present invention will be described in detail below with reference to specific embodiments.

Example 1

A preparation method of a sulphoaluminate-magnesium aluminate spinel cementing material comprises the following specific steps:

as shown in figure 1, the secondary aluminum ash is treated by an external heating rotary kiln under the condition of oxygen enrichment (30 percent by volume of oxygen) and at 1050 ℃, so that the aluminum nitride in the secondary aluminum ash is converted into aluminum oxide to form calcined aluminum ash, sodium fluoride and sodium potassium salt are volatilized and condensed at high temperature,the functions of denitrification, defluorination and desalination of the secondary aluminum ash are realized, and the desalted high-temperature flue gas (the volume fraction of oxygen is 19%) is conveyed to a dryer. Crushing 30 parts by mass of desulfurized magnesium slag, 20 parts by mass of dolomite tailings and 35 parts by mass of carbide slag, then sending the crushed materials into a dryer for drying to form a mixture, and then mixing the mixture with 80 parts by mass of calcined aluminum ash, wherein a heat source of the dryer is desalted high-temperature flue gas generated by calcining the aluminum ash by an external heating rotary kiln; according to the components of the raw materials in the dryer, adding correction materials (calcined aluminum ash, dried desulfurized magnesium slag and dried carbide slag) for raw material matching to form a sulphoaluminate-magnesia-alumina spinel cementitious material raw material, wherein the weight ratio of the calcined aluminum ash to the dried desulfurized magnesium slag to the dolomite tailings to the carbide slag is 80:30:20:35 based on the solid matter of the dried matched raw material. The matched raw materials are directly conveyed into a rotary cement kiln for calcination through raw material grinding, the calcination temperature is 1260 ℃, and the calcination time is 30 minutes. The high-temperature flue gas generated by the calcination of the rotary cement kiln and the desalted flue gas generated by the dryer heat the dryer, and then the flue gas is sent to a waste heat recovery device after high-temperature dust removal and denitrification to form high-temperature water for the operation of related air conditioning equipment. The kiln gas temperature after passing through the waste heat recoverer is reduced to 150 ℃, and the kiln gas is discharged after reaching the national flue gas emission standard after being desulfurized and dedusted. Cooling the sulphoaluminate-magnesia-alumina spinel gelled material generated in the cement rotary kiln by an indirect cooler to obtain the sulphoaluminate-magnesia-alumina spinel high-temperature resistant special gelled material, as shown in figure 2, the main phase of the material is 3CaO 3Al₂O₃·CaSO₄、MgAl₂O₄、2CaO·SiO₂And magadiite Ca₃MgSi₂O₈Meanwhile, a small amount of free MgO is contained, the content of the free MgO is 65%, 20% and 8%, and the content of the magnesia-alumina spinel is 20%, which belongs to a low-magnesia-alumina spinel sulphoaluminate-magnesia-alumina spinel cementing material. Table 1 shows that the strength of the 20% magnesia-alumina spinel-containing cementing material after 150 ℃ heating treatment and without heating treatment at different hydration times is compared, and the high temperature resistance of the composite cementing material can be effectively improved when certain mei-alumina spinel exists in certain clinker minerals.

TABLE 1 comparison of compressive strengths of thioaluminate-magnesium aluminate spinel cementitious materials

Example 2

A preparation method of a sulphoaluminate-magnesium aluminate spinel cementing material comprises the following specific steps:

treating the secondary aluminum ash by an external heating rotary kiln at 1050 ℃ under an oxygen-rich condition (the volume fraction of oxygen is 30 percent), so that the aluminum nitride in the secondary aluminum ash is converted into aluminum oxide, and sodium fluoride and sodium potassium salts are volatilized and condensed at high temperature to realize the functions of denitrification, defluorination and desalination of the secondary aluminum ash; crushing 42 parts by mass of desulfurized magnesium slag, 18 parts by mass of dolomite tailings and 30 parts by mass of carbide slag, feeding the crushed materials into a rotary dryer for drying to form a mixture, and mixing the mixture with 95 parts by mass of calcined aluminum ash, wherein a heat source of the dryer is high-temperature flue gas generated by calcining the aluminum ash in a calcining kiln; according to the components of the raw materials in the dryer, correction materials (calcined aluminum ash, dried desulfurized magnesium slag and dried carbide slag) are added for raw material matching to form a special sulphoaluminate-magnesia-alumina spinel cementing material raw material, and the weight ratio of the pretreated aluminum ash, the dried desulfurized magnesium slag, dolomite tailings and the carbide slag is 95:42:18:30 based on the solid matter of the dried matched raw material. The matched raw materials are directly conveyed into a rotary cement kiln for calcination through raw material grinding, the calcination temperature is 1260 ℃, and the calcination time is 30 minutes. The high-temperature flue gas generated by the calcination of the rotary cement kiln and the flue gas generated by the dryer heat the dryer, and then the flue gas is sent to a waste heat recovery device after high-temperature dust removal and denitrification to form high-temperature water for the operation of related air conditioning equipment. The kiln gas temperature after passing through the waste heat recoverer is reduced to 150 ℃, and the kiln gas is discharged after reaching the national flue gas emission standard after being desulfurized and dedusted. Cooling the special sulphoaluminate-magnesia-alumina spinel high-temperature resistant gelled material generated in the cement rotary kiln by an indirect cooler to obtain the sulphoaluminate-magnesia-alumina spinel gelled material, wherein the main phase of the material is 3CaO 3Al as shown in figure 3₂O₃·CaSO₄、MgAl₂O₄、2CaO·SiO₂The content of the magnesium aluminate spinel is respectively 55%, 30% and 8%, and the content of the magnesium aluminate spinel is 30%, which belongs to a special cementing material with higher magnesium aluminate spinel content. The compression strength of a standard test block (20mm multiplied by 20mm) made of the special cementing material after hydration curing and the strength after high-temperature treatment at 150 ℃ are shown in Table 2.

TABLE 2 comparison of compressive strengths of thioaluminate-magnesium aluminate spinel cementitious materials

Comparative example 1

This comparative example is the same as example 1, except that: the sulphoaluminate-magnesium aluminate spinel gel material with the magnesium aluminate spinel content of 10 percent is prepared.

The sulphoaluminate-magnesium aluminate spinel cementing material prepared in the examples 1-2 and the comparative example 1 and the sulphoaluminate cement are taken as standard test blocks, cured for 28 days and treated at 150 ℃, and the result is shown in figure 4. The cracks of the standard test block prepared by the sulphoaluminate cement and the gelled material formed in the comparative example 1 are shown to exist at the temperature of 150 ℃, and the cracks of the standard test block prepared by the gelled material formed in the examples 1-2 are not generated after the standard test block is treated at the temperature of 150 ℃, so that the sulphoaluminate-magnesia-alumina spinel gelled material prepared by the invention has thermal shock resistance.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.