A system and method for co-production of high-temperature-resistant oil well cement and sulfur using industrial solid waste

Abstract

This invention relates to the fields of deep energy extraction, comprehensive utilization of industrial solid waste resources, and environmental protection and management. Specifically, it relates to a system and method for producing high-temperature resistant oil well cement and co-producing sulfur from industrial solid waste. This invention utilizes industrial solid waste—magnesium slag, steel slag, aluminum ash, and desulfurized gypsum—to prepare high-temperature resistant oil well cement-based materials, while simultaneously producing sulfur, thus achieving high-value utilization of industrial solid waste.

Description

Technical Field

[0001] This invention relates to the fields of deep energy extraction, comprehensive utilization of industrial solid waste resources, and environmental protection and management, specifically to a system and method for producing high-temperature resistant oil well cement and co-producing sulfur using industrial solid waste. Background Technology

[0002] With rapid economic development, the demand for geological resources is increasing daily. In the ongoing extraction of resources, shallow surface resources are gradually failing to meet demand, making the expansion into deeper and ultra-deep formations an inevitable trend. Deep oil and gas resources have been the main driver of global proven reserves growth over the past decade, continuously breaking through the lower limit of effective resource retention depth. The extraction of deep oil and gas resources relies on deep and ultra-deep well cementing technology, but this process faces major technical challenges such as high temperature, high pressure, high salinity, and corrosive formation water.

[0003] Traditional cement-based cementing materials mainly include silicate cement, aluminate cement, phosphate cement, and geopolymers. Silicate cement is a relatively mature cementing material with significant advantages in terms of economy and operability; however, its use in deep and ultra-deep well cementing has significant drawbacks: ① It easily forms a "weak interface" in the cement sheath bonding. ② Corrosive gases (H2S, SO2) cause interface instability, damaging the integrity of the oil and gas well. Compared to silicate cement, aluminate cement has advantages in high temperature resistance and dense structure, particularly in terms of high temperature and early strength. However, the concentrated heat release during the hardening of aluminate cement slurry leads to large temperature variations during hardening, causing the internal temperature to significantly exceed the external temperature during slurry formation. This results in significant temperature stress, causing cracks on the cement stone surface, reducing the strength of the cement stone, and increasing its permeability. Furthermore, the inherent properties of aluminate cement make the prepared cement slurry difficult to apply, which is detrimental to cementing quality. Phosphate cement possesses resistance to high-temperature degradation and corrosion, but its initial hydration rate is too rapid, its anti-pollution ability is poor, and its water resistance is low; it flash-sets immediately upon contact with ordinary silicate cement. Geopolymers exhibit high-temperature resistance, durability, low permeability, and good interfacial bonding properties, but they still suffer from problems such as unstable raw materials and high costs of alkali activators. Therefore, the above-mentioned conventional inorganic cementing materials all have certain limitations in the application of high-temperature oil well cementing environments. Thus, there is an urgent need to develop special cementing materials that are resistant to high temperatures and salt penetration, have a wide applicable temperature range, and possess excellent and stable mechanical properties. This will improve the level of high-temperature cementing slurry technology, meet the cementing technology requirements of complex wells such as deep and ultra-deep wells, and provide important technical support for "increased production and storage" in the development of deep oil and gas resources.

[0004] At the same time, the massive increase in the types and quantities of industrial products has generated various industrial solid wastes, such as magnesium slag, steel slag, aluminum ash, and desulfurization gypsum, causing serious water, soil and air pollution and a series of resource wastes, making it urgent to realize the high-value utilization of various industrial solid wastes. Summary of the Invention

[0005] To overcome the above problems, this invention provides a system and method for producing high-temperature resistant oil well cement and co-producing sulfur using industrial solid waste. This invention utilizes industrial solid waste—magnesium slag, steel slag, aluminum ash, and desulfurized gypsum—to prepare high-temperature resistant oil well cement-based materials, while simultaneously producing sulfur, thus achieving high-value utilization of industrial solid waste.

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

[0007] The first aspect of the present invention provides a method for producing high-temperature resistant oil well cement and co-producing sulfur using industrial solid waste, comprising the following steps:

[0008] (1) Aluminum ash is put into microwave rapid oxidation-reduction equipment for pretreatment. The pretreatment temperature is set to 950-1050℃. After pretreatment, aluminum ash produces high-temperature gas and solid.

[0009] (2) Grind and dry steel slag, magnesium slag and desulfurized gypsum;

[0010] (3) The pretreated aluminum ash solids, as well as the dried steel slag, magnesium slag and desulfurized gypsum, are fed into the automatic batching system for mixing, grinding and homogenization.

[0011] (4) The raw meal mixture after batching is fed into a calcining kiln for calcination. The calcination produces a high-temperature cement-based material containing magnesium aluminum spinel (MA), calcium aluminoferrite (C4AF), calcium sulfoaluminate (C4A3$) and dicalcium silicate (C2S) as well as high-temperature flue gas containing SO2. The cement-based material containing magnesium aluminum spinel (MA), calcium aluminoferrite (C4AF), calcium sulfoaluminate (C4A3$) and dicalcium silicate (C2S) is the high-temperature resistant oil well cementing cement-based material.

[0012] (5) High-temperature flue gas containing SO2 enters a cyclone dust collector and a metal mesh high-temperature dust collector for dust removal, and then enters a sulfur dioxide absorption and reduction conversion device to reduce and convert sulfur.

[0013] A second aspect of the present invention provides a system for producing high-temperature resistant oil well cement and co-producing sulfur using industrial solid waste, comprising: a microwave rapid oxidation-reduction device and a hot air drying and grinding mill, wherein both the microwave rapid oxidation-reduction device and the hot air drying and grinding mill are connected to an automatic batching system, the automatic batching system is connected to a calcining kiln, the calcining kiln is sequentially connected to a cyclone dust collector, a metal mesh high-temperature dust collector, and a sulfur dioxide absorption and conversion device, the calcining kiln is also connected to a high-temperature resistant oil well cement storage tank, and the sulfur dioxide absorption and conversion device is connected to a sulfur storage tank.

[0014] The beneficial effects of this invention are as follows:

[0015] (1) Existing high-temperature resistant oil well cement mainly uses 30-40% silicate sand of different particle sizes to prepare G-grade cement by compounding with silicate cement. This gives it advantages such as high temperature resistance, right-angle thickening, and short static cementitious strength transition time. The basic principle that it can meet the cementing requirements of high-temperature oil wells is that silicate sand can prevent the strength of cement stone from decaying at high temperatures. The addition of silicate sand can reduce the permeability of cement stone. The smaller the particle size of silicate sand, the lower the permeability of cement stone. In cement stone with larger particle size silicate sand, the needle-like hard calcium silicate formed is longer, giving the cement stone higher compressive strength. Therefore, it can be seen that silicate sand of different particle sizes with no hydration activity and high temperature resistance plays a promoting role in the hydration of cement stone to form a dense structure and special hydration products. Based on the above conclusions, it is proposed to introduce materials such as magnesium aluminum spinel and calcium iron aluminate with different particle sizes into the cementitious material system of calcium sulfoaluminate and dicalcium silicate, so that the final cementitious material has the characteristics of high temperature resistance and high temperature phase transformation stability of hydration products, so that the cement-based material prepared can be applied to the cementing application field of deep and ultra-deep oil and gas wells.

[0016] To achieve the above goals, aluminum ash, magnesia slag, steel slag, and desulfurized gypsum are used to replace high-grade bauxite, magnesite, limestone, and gypsum. Magnesium-containing compounds in industrial solid waste react with aluminum in the aluminum ash at high temperatures to directly generate MgAl2O4 of different particle sizes. However, the aluminum in the aluminum ash exists in the forms of aluminum nitride, elemental aluminum, and aluminum oxide. Therefore, it is necessary to remove nitrogen from the aluminum nitride compound and oxidize the aluminum in a microwave rapid oxidation-reduction device. In this high-temperature oxidation-reduction device, aluminum nitride is mainly converted into Al2O3 and nitrogen. The main component of the pretreated aluminum ash is Al2O3. The pretreated aluminum ash is then matched with desulfurized gypsum, steel slag, and magnesia slag abrasive. The matched system contains the main raw materials for the formation of minerals such as magnesium aluminum spinel (MA), calcium aluminoferrite (C4AF), calcium sulfoaluminate (C4A3), and dicalcium silicate (C2S), as well as by-product sulfur. Then, calcination is carried out in a calcining kiln to synthesize magnesium aluminum spinel (MA), calcium aluminoferrite (C4AF), calcium sulfoaluminate (C4A3$), and dicalcium silicate (C2S). The specific synthesis process is represented by the following equation:

[0017] 3CaO + 3Al₂O₃ + CaSO₄ → 3CaO·3Al₂O₃·CaSO₄ (Calcium sulfoaluminate C₄A₃)

[0018] 4CaO + Al₂O₃ + Fe₂O₃ → 4CaO·Al₂O₃·Fe₂O₃ (Calcium aluminoferrite C₄AF)

[0019] 2CaO + SiO2 → 2CaO·SiO2 (Dicalcium silicate C2S)

[0020] MgO + Al₂O₃ → MgO·Al₂O₃ (Magnesium Aluminum Spinel, MA)

[0021] Determining the calcination temperature requires consideration of two factors: firstly, the synthesis and stability of each mineral; and secondly, the optimization of the particle size distribution of MA minerals. MA can be generated at 900–1700℃, while clinker minerals such as C4AF, C4A3$, and C2S can be generated and stabilized at 1200–1350℃. However, C4A3$ minerals are prone to decomposition and are difficult to stabilize above 1350℃. Furthermore, as the temperature increases, the size of MA increases. Larger MA particles have a nucleation effect during hydration and can inhibit crack formation at high temperatures. Therefore, the calcination temperature is limited to 1200–1350℃.

[0022] Meanwhile, during the formation of calcium sulfoaluminate, some of the desulfurized gypsum decomposes, resulting in a higher concentration of sulfur dioxide in the flue gas. Through a sulfur dioxide adsorption, desorption, and reduction conversion device, the sulfur dioxide in the flue gas can be directly converted into sulfur, thus achieving the purpose of co-producing sulfur.

[0023] (2) The cement-based material containing magnesium aluminum spinel (MA), calcium aluminoferrite (C4AF), calcium sulfoaluminate (C4A3$) and dicalcium silicate (C2S) provided in this invention was subjected to high temperature resistance tests after being hardened with ordinary sulfoaluminate cement. The results showed that the cement-based material prepared in this invention did not generate cracks at 800℃. This is because the large-sized MA has a nucleation effect during hydration and has the function of inhibiting crack generation under high temperature environment.

[0024] (2) In this invention, the high-temperature gas generated in the microwave rapid oxidation-reduction equipment is used as a hot air heat source and sent to the hot air drying mill to achieve the grinding, refining, and drying of steel slag, magnesium slag, and desulfurized gypsum. Simultaneously, the high-temperature flue gas generated in the calcining kiln, after dust removal, enters the air preheater to generate high-temperature air. This high-temperature air heats the air entering the calcining kiln and the microwave rapid oxidation-reduction equipment, increasing the temperature of the air entering these equipment and thus improving thermal efficiency. In addition to reducing SO2 to sulfur in the sulfur dioxide absorption-reduction conversion device, high-temperature flue gas is also generated. This high-temperature flue gas enters the hot air drying mill and the blower mill in the automatic batching system, providing energy for the drying and pneumatic conveying of materials in these systems. Through the above efficient utilization of energy, this invention can significantly reduce the consumption of coal and electricity, thereby fundamentally achieving energy conservation and consumption reduction.

[0025] Meanwhile, this invention also considers the treatment of dust-laden flue gas in the blower mill. The dust-laden flue gas in the blower mill of the automatic batching system is treated by a cyclone dust collector, and the treated air that meets the standards is discharged into the atmosphere. The collected dust is then incorporated into the mixed raw materials for the preparation of high-temperature resistant cement-based materials. Treating the dust-laden flue gas in the blower mill allows for the recovery of reaction raw materials while preventing air pollution from the flue gas.

[0026] (3) This invention utilizes industrial solid wastes—magnesium slag, steel slag, aluminum ash, and desulfurized gypsum—to prepare high-temperature resistant oil well cementitious materials, while simultaneously producing sulfur. It has significant application value, and its implementation can generate outstanding economic and environmental benefits. Furthermore, the entire industrial process of this invention is simple, requires low energy consumption, and is easy to promote industrially. Attached Figure Description

[0027] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0028] Figure 1 This is a process flow diagram of the present invention;

[0029] Figure 2 The image shows the XRD pattern of the high-temperature resistant cementitious clinker obtained in Example 1.

[0030] Figure 3 The image shows a scanning electron microscope (SEM) image of the high-temperature resistant cementitious clinker obtained in Example 1.

[0031] Figure 4 This is a distribution diagram of the hydration products of the high-temperature resistant cementitious clinker obtained in Example 1;

[0032] Figure 5 The results of high-temperature resistance tests were conducted on the high-temperature resistant cementitious clinker obtained in Example 1 and the ordinary sulfoaluminate cement after hardening. Detailed Implementation

[0033] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0034] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0035] A first typical embodiment of the present invention, a method for producing high-temperature resistant oil well cement and co-producing sulfur using industrial solid waste, includes the following steps:

[0036] (1) Aluminum ash is put into microwave rapid oxidation-reduction equipment for pretreatment. The pretreatment temperature is set to 950-1050℃. After pretreatment, aluminum ash produces high-temperature gas and solid.

[0037] (2) Grind and dry steel slag, magnesium slag and desulfurized gypsum;

[0038] (3) The pretreated aluminum ash solids, as well as the dried steel slag, magnesium slag and desulfurized gypsum, are fed into the automatic batching system for mixing, grinding and homogenization.

[0039] (4) The raw meal mixture after batching is fed into a calcining kiln for calcination. The calcination produces a high-temperature cement-based material containing magnesium aluminum spinel (MA), calcium aluminoferrite (C4AF), calcium sulfoaluminate (C4A3$) and dicalcium silicate (C2S) as well as high-temperature flue gas containing SO2. The cement-based material containing magnesium aluminum spinel (MA), calcium aluminoferrite (C4AF), calcium sulfoaluminate (C4A3$) and dicalcium silicate (C2S) is the high-temperature resistant oil well cementing cement-based material.

[0040] (5) High-temperature flue gas containing SO2 enters a cyclone dust collector and a metal mesh high-temperature dust collector for dust removal, and then enters a sulfur dioxide absorption and reduction conversion device to reduce and convert sulfur.

[0041] In one or more embodiments, in step (1), an iron-based dispersant that can generate local hot spots is added, which can cause the local temperature to rise rapidly to 950-1050°C under the action of microwaves.

[0042] The iron dispersant consists of silicon carbide (SiC), iron(II,III) oxide (Fe3O4), activated carbon, and iron oxide, with a mass ratio of 36:42:15:7.

[0043] In one or more embodiments, in step (1), the main components of the aluminum ash include metallic aluminum, aluminum oxide, aluminum nitride, and a small amount of salts. Under high temperature conditions of 950 to 1050°C, metallic aluminum reacts with oxygen to generate aluminum oxide, aluminum nitride reacts with oxygen to generate aluminum oxide and nitrogen, and a small amount of salts rapidly sublimates and is then removed. The main component of the pretreated aluminum ash solid is aluminum oxide, and the salt content in the pretreated aluminum ash solid is controlled to be less than 1.5%.

[0044] In one or more embodiments, in step (1), the high-temperature gas generated in the microwave rapid oxidation-reduction equipment is used as a hot air heat source and sent into the hot air drying and grinding mill to achieve grinding, refining and drying of steel slag, magnesium slag and desulfurized gypsum.

[0045] Preferably, the high-temperature gas generated in the microwave rapid oxidation-reduction equipment includes a mixture of nitrogen gas produced by the reaction of aluminum nitride with oxygen, air gas, and other flue gases.

[0046] In one or more embodiments, in step (3), the automatic batching system includes a mixing batching machine and a blower mill.

[0047] In one or more embodiments, in step (3), if the solids after aluminum ash pretreatment and the dried steel slag, magnesium slag and desulfurized gypsum are difficult to meet the requirements of the mineral composition of clinker after being mixed and batched, it is necessary to compound and adjust them with correcting materials limestone, bauxite, magnesite and iron ore to prepare raw meal with the required composition.

[0048] In one or more embodiments, in step (4), the chemical components contained in the raw material mixture after the ingredients are prepared are: Al2O3: 40-55 parts by weight; MgO: 8-15 parts by weight; CaO: 20-28 parts by weight; SO3: 10-18 parts by weight; SiO2: 8-12 parts by weight; Fe2O3: 5-8 parts by weight.

[0049] In one or more embodiments, in step (4), the calcination temperature is 1200-1350°C and the calcination time is 45-60 min.

[0050] In one or more embodiments, in step (4), the molar ratio of magnesium aluminum spinel (MA), calcium aluminoferrite (C4AF), calcium sulfoaluminate (C4A3$) and dicalcium silicate (C2S) in the cement-based material is (1-3):(1-2):(1-3):(1-2).

[0051] In one or more embodiments, in step (5), the high-temperature flue gas containing SO2 enters a cyclone dust collector and a metal mesh high-temperature dust collector for dust removal treatment, and the dust concentration in the flue gas after dust removal is less than 10 g / NM. 3 It is then adsorbed and desorbed in the sulfur dioxide absorption and conversion device, and then converted into sulfur through a rapid reduction device.

[0052] Preferably, the high-temperature SO2 gas after dust removal is preheated by an air preheater before being adsorbed and desorbed, resulting in high-temperature air. This high-temperature air heats the air entering the calcining kiln and the microwave rapid oxidation-reduction equipment, thereby increasing the temperature of the air entering the calcining kiln and the microwave rapid oxidation-reduction equipment and thus improving thermal efficiency.

[0053] Preferably, in addition to reducing SO2 to produce sulfur in the sulfur dioxide absorption, reduction and conversion device, high-temperature flue gas is also generated. The high-temperature flue gas enters the hot air drying mill and the blower mill in the automatic batching system to provide energy for the drying and pneumatic conveying of materials in the hot air drying mill and the blower mill in the automatic batching system.

[0054] In a further preferred embodiment, the dust-laden flue gas in the blower mill of the automatic batching system is treated by a cyclone dust collector, and the qualified air after dust removal is discharged into the air. The collected dust is mixed into the raw materials and used to prepare high-temperature resistant cement-based materials.

[0055] A second typical embodiment of the present invention provides a system for producing high-temperature resistant oil well cement and co-producing sulfur using industrial solid waste, comprising: a microwave rapid oxidation-reduction device and a hot air drying and grinding mill, wherein both the microwave rapid oxidation-reduction device and the hot air drying and grinding mill are connected to an automatic batching system, the automatic batching system is connected to a calcining kiln, the calcining kiln is sequentially connected to a cyclone dust collector, a metal mesh high-temperature dust collector, and a sulfur dioxide absorption and conversion device, the calcining kiln is also connected to a high-temperature resistant oil well cement storage tank, and the sulfur dioxide absorption and conversion device is connected to a sulfur storage tank.

[0056] In one or more embodiments, the microwave rapid oxidation-reduction device is connected to the hot air drying and grinding mill.

[0057] In one or more embodiments, the automatic batching system includes a mixing batching machine and a blower mill.

[0058] Preferably, the mixing and batching machine is connected to the blower mill, and the blower mill is connected to the calcining kiln through the aging chamber.

[0059] Preferably, the microwave rapid oxidation-reduction equipment and the hot air drying and grinding mill are both connected to the mixing and batching machine.

[0060] Preferably, the blower mill is connected to a cyclone dust collector, and the cyclone dust collector is connected to a mixing and batching machine.

[0061] In one or more embodiments, an air preheater is provided between the high-temperature dust collector and the sulfur dioxide absorption and conversion device, and the air preheater is connected to the calcining kiln and the microwave rapid oxidation-reduction equipment, respectively.

[0062] In one or more embodiments, the sulfur dioxide absorption and conversion device is connected to a hot air drying mill and a blower mill in an automatic batching system.

[0063] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0064] Example 1

[0065] refer to Figure 1The process flow shown involves pretreatment of aluminum ash in a microwave rapid oxidation-reduction (RER) device. An iron-based dispersant is added to create hot spots; the amount of dispersant added is 2% of the total aluminum ash volume. The dispersant consists of silicon carbide (SiC), iron(III) oxide (Fe3O4), activated carbon, and iron oxide, with a mass ratio of 36:42:15:7. In the RER device, the aluminum nitride and elemental aluminum within the aluminum ash are converted to aluminum oxide. This process achieves denitrification and oxidation, while also enabling the high-temperature removal of some chloride salts from the aluminum ash.

[0066] Steel slag, magnesium slag, and desulfurized gypsum are added to a hot air drying mill for grinding and drying; the heat source for grinding and drying comes from the high-temperature flue gas generated by the sulfur dioxide absorption-reduction conversion device and the high-temperature gas processed by the microwave rapid oxidation-reduction equipment.

[0067] The pretreated aluminum ash solids, along with dried steel slag, magnesium slag, and desulfurized gypsum, are fed into a mixing and batching machine in an automatic batching system for batching. Based on the composition of the dried raw materials, checker materials (limestone, bauxite, magnesite, and iron ore) are added to match the raw materials, forming a high-temperature resistant cementitious base material containing magnesium aluminum spinel, calcium aluminoferrite, calcium sulfoaluminate, and dicalcium silicate. Based on the dried, matched raw meal solids, the mass ratio of desulfurized gypsum to steel slag, magnesium slag, and aluminum ash is 25:24:29:21. The chemical composition of the completed raw meal mixture is: Al₂O₃: 41.4 parts by weight; MgO: 12.2 parts by weight; CaO: 21.8 parts by weight; SO₃: 11.4 parts by weight; SiO₂: 6.7 parts by weight; Fe₂O₃: 6.5 parts by weight.

[0068] The raw material mixture after batching is fed into a blower mill for grinding and drying. The heat source for drying and the pneumatic conveying of the blower mill come from the high-temperature flue gas generated by the sulfur dioxide absorption-reduction conversion unit.

[0069] The raw material mixture after batching is fed into a calcining kiln for calcination at a temperature of 1300℃ for 60 minutes. The calcination time is adjusted to control the particle size of the calcium sulfoaluminate and magnesium aluminum spinel during calcination.

[0070] The calcining kiln produces high-temperature flue gas containing SO2. This SO2-containing flue gas undergoes dust removal treatment in a cyclone dust collector and a metal mesh high-temperature dust collector, and then enters an air preheater to preheat the air, realizing the utilization of waste heat from the high-temperature flue gas. After passing through the waste heat utilization equipment in the air preheater, the temperature of the high-temperature flue gas is reduced by 100-200℃, and it enters a sulfur dioxide absorption, reduction, and conversion unit. Through processes such as SO2 gas adsorption, desorption, and rapid reduction conversion, it is converted into elemental sulfur with a mass fraction of not less than 95%.

[0071] High-temperature resistant cementitious clinker containing magnesium aluminum spinel (MA), calcium sulfoaluminate (C4A3), calcium aluminoferrite (C4AF), and dicalcium silicate (C2S), prepared in a rotary kiln, is subjected to forced cooling in a grate cooler to obtain high-temperature resistant cementitious clinker. The clinker contains 55% calcium sulfoaluminate (C4A3), 10% magnesium aluminum spinel (MA), 15% calcium aluminoferrite (C4AF), and 15% dicalcium silicate (C2S). The specific surface area of ​​the prepared cementitious material is 7.3 m². 2 / g, with over 95% of the particles having a size of less than 340 mesh.

[0072] Figure 2 The image shows the XRD pattern of the high-temperature resistant cementitious clinker obtained in this embodiment. It can be seen from the image that the high-temperature resistant cementitious clinker containing magnesium aluminum spinel (MA), calcium sulfoaluminate (C4A3), calcium ferroaluminate (C4AF), and dicalcium silicate (C2S) prepared in this embodiment is a high-temperature resistant cementitious clinker.

[0073] Figure 3 This is a scanning electron microscope image of the high-temperature resistant cementitious clinker obtained in Example 1.

[0074] Figure 4 This is a distribution diagram of the hydration products of the high-temperature resistant cementitious clinker obtained in this embodiment, illustrating that the magnesium aluminum spinel generated by the first calcination can be uniformly distributed in the hydration products during the hydration process, which can prevent the propagation of hot cracks under high temperature.

[0075] The high-temperature cement-based material containing magnesium aluminum spinel (MA), calcium aluminoferrite (C4AF), calcium sulfoaluminate (C4A3$), and dicalcium silicate (C2S) prepared in this embodiment was subjected to high-temperature resistance tests after being hardened with ordinary sulfoaluminate cement. The results are as follows: Figure 5 As shown, the high-temperature cement-based material prepared in this embodiment does not generate cracks at 800°C. This is because the large-sized MA has a nucleation effect during hydration and has the function of inhibiting crack generation under high-temperature conditions.

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for producing high-temperature resistant oil well cement and co-producing sulfur using industrial solid waste, characterized in that, Includes the following steps: (1) Aluminum ash is put into microwave rapid oxidation-reduction equipment for pretreatment. The pretreatment temperature is set to 950~1050 ℃. After pretreatment, aluminum ash produces high-temperature gas and solid. (2) Grind and dry the steel slag, magnesium slag and desulfurized gypsum powder; (3) The solids after aluminum ash pretreatment, as well as the dried steel slag, magnesium slag and desulfurized gypsum, are fed into the automatic batching system for mixing, grinding and homogenization; (4) The raw material mixture after batching is fed into the calcining kiln for calcination. The calcination produces high-temperature cement-based materials containing magnesium aluminum spinel (MA), calcium aluminoferrite (C4AF), calcium sulfoaluminate (C4A3$) and dicalcium silicate (C2S) as well as high-temperature flue gas containing SO2. The cement-based materials containing magnesium aluminum spinel (MA), calcium aluminoferrite (C4AF), calcium sulfoaluminate (C4A3$) and dicalcium silicate (C2S) are high-temperature resistant oil well cement-based materials. (5) High-temperature flue gas containing SO2 enters a cyclone dust collector and a metal mesh high-temperature dust collector for dust removal, and then enters a sulfur dioxide absorption and reduction conversion device to reduce and convert sulfur.

2. The method as described in claim 1, characterized in that, In step (1), an iron-based dispersant that can generate local hot spots is added, which can rapidly raise the local temperature to 950~1050 ℃ under the action of microwaves; the composition of the iron dispersant includes: silicon carbide (SiC), iron(II,III) oxide (Fe3O4), activated carbon and iron oxide, wherein the mass ratio of each substance is 36:42:15:

7. Alternatively, in step (1), the high-temperature gas generated in the microwave rapid oxidation-reduction equipment is used as a hot air heat source and sent into the hot air drying and grinding mill to achieve the grinding, refining and drying of steel slag, magnesium slag and desulfurized gypsum.

3. The method as described in claim 1, characterized in that, In step (3), the automatic batching system includes a mixing batching machine and a blower mill; Alternatively, in step (3), if the pretreated solid aluminum ash and the dried steel slag, magnesium slag and desulfurized gypsum are mixed and batched to meet the requirements of the mineral composition of the clinker, it is necessary to further mix and adjust it with the correcting materials limestone, bauxite, magnesite and iron ore to prepare raw meal with the required composition.

4. The method as described in claim 1, characterized in that, In step (4), the chemical components contained in the raw material mixture after the ingredients are prepared are: Al2O3: 40~55 parts by weight; MgO: 8~15 parts by weight; CaO: 20~28 parts by weight; SO3: 10~18 parts by weight; SiO2: 8~12 parts by weight; Fe2O3: 5~8 parts by weight; Alternatively, in step (4), the calcination temperature is 1200~1350 ℃ and the calcination time is 45~60 min.

5. The method as described in claim 1, characterized in that, In step (4), the molar ratio of magnesium aluminum spinel (MA), calcium aluminoferrite (C4AF), calcium sulfoaluminate (C4A3$), and dicalcium silicate (C2S) in the high-temperature cement-based material is (1~3):(1~2):(1~3):(1~2).

6. The method as described in claim 1, characterized in that, In step (5), the high-temperature flue gas containing SO2 enters a cyclone dust collector and a metal mesh high-temperature dust collector for dust removal treatment. The dust concentration in the flue gas after dust removal is less than 10 g / NM. 3 It is then adsorbed and desorbed in the sulfur dioxide absorption and conversion device, and then converted into sulfur through a rapid reduction device.

7. The method as described in claim 6, characterized in that, Before being adsorbed and desorbed, the high-temperature SO2 gas after dust removal passes through an air preheater to preheat the air, resulting in high-temperature air. This high-temperature air then heats the air entering the calcining kiln and the microwave rapid oxidation-reduction equipment, increasing the temperature of the air entering these equipment and thus improving thermal efficiency. Alternatively, in addition to reducing SO2 to produce sulfur in the sulfur dioxide absorption, reduction and conversion device, high-temperature flue gas is also generated. This high-temperature flue gas enters the hot air drying mill and the blower mill in the automatic batching system, providing energy for the drying of materials and pneumatic conveying in the hot air drying mill and the blower mill in the automatic batching system. The dust-laden flue gas in the blower mill of the automatic batching system is treated by a cyclone dust collector, and the qualified air after dust removal is discharged into the air. The collected dust is then mixed into the raw materials for the preparation of high-temperature resistant cement-based materials.

8. A system for implementing the method according to any one of claims 1 to 7, characterized in that, include: The equipment includes a microwave rapid oxidation-reduction device and a hot air drying and grinding mill. Both the microwave rapid oxidation-reduction device and the hot air drying and grinding mill are connected to an automatic batching system. The automatic batching system is connected to a calcining kiln. The calcining kiln is sequentially connected to a cyclone dust collector, a metal mesh high-temperature dust collector, and a sulfur dioxide absorption and conversion device. The calcining kiln is also connected to a high-temperature resistant oil well cementing storage tank. The sulfur dioxide absorption and conversion device is connected to a sulfur storage tank.

9. The system as described in claim 8, characterized in that, The microwave rapid oxidation-reduction equipment is connected to the hot air drying and grinding mill; Alternatively, the automatic batching system includes a mixing and batching machine and a blower mill, wherein the mixing and batching machine is connected to the blower mill, and the blower mill is connected to the calcining kiln through an aging chamber; the microwave rapid oxidation-reduction equipment and the hot air drying mill are both connected to the mixing and batching machine; the blower mill is connected to a cyclone dust collector, and the cyclone dust collector is connected to the mixing and batching machine.

10. The system as described in claim 8, characterized in that, An air preheater is provided between the high-temperature dust collector and the sulfur dioxide absorption and conversion device. The air preheater is connected to the calcining kiln and the microwave rapid oxidation-reduction equipment, respectively. Alternatively, the sulfur dioxide absorption and conversion device may be connected to both the hot air drying mill and the blower mill in the automatic batching system.

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