Method for low-energy-consumption preparation of solid waste regenerated material in composite maintenance system

Abstract

Disclosed in the present invention is a method for low-energy-consumption preparation of a solid waste regenerated material in a composite maintenance system. The method comprises the following steps: S1, preparing solid waste into a blank of a building material; S2, placing the blank of the building material into a reaction kettle, introducing a flue gas into same to perform a mineralization treatment, and terminating the mineralization treatment when the temperature in the reaction kettle reaches a given temperature; and S3, subjecting the mineralized blank of the building material to a hydrothermal treatment, so as to obtain a building material product. In the present invention, on the basis of the exothermic nature of mineralization reactions, mineralization is coupled with a hydrothermal method in order to utilize the heat generated by early-stage mineralization and omit an external heating source required for a subsequent hydrothermal reaction, thereby meeting the requirements for both economical efficiency and product performance.

Description

Method for preparing solid waste recycled materials with low energy consumption under composite curing system Technical Field

[0001] The present invention relates to the technical field of industrial solid waste treatment, and in particular to a method for preparing solid waste recycled materials with low energy consumption under a composite curing system. Background Art

[0002] With the continued acceleration of industrial development, annual emissions from high-carbon-emitting industries such as steel, coal chemical industry, power generation, and cement have far exceeded the atmospheric tolerance limit, causing severe environmental problems such as the greenhouse effect. Furthermore, ongoing industrial activity is accompanied by the generation of large quantities of solid waste. Existing solid waste treatment methods typically include high-temperature sintering, chemical treatment, and landfill storage, all of which are associated with high energy consumption, secondary pollution, and a lack of added value. However, most solid wastes inherently contain reusable elements and can generate significant added value with appropriate treatment. For example, calcium-based solid wastes such as steel slag, carbide slag, slag, blast furnace slag, manganese slag, red mud, and magnesium slag, as well as silicon-aluminum-based solid wastes such as fly ash, glass tailings, construction waste, bottom ash, red mud, and ore raw materials, contain elements such as calcium, silicon, and aluminum. In the presence of water vapor and carbon dioxide, these elements can form products with specific mechanical properties. This allows for the production of high-value-added products while consuming solid waste and capturing carbon dioxide.

[0003] Existing methods for producing building materials from solid waste primarily rely on autoclaving and mineralization. For example, patent CN113135704A provides a method for producing building materials from solid waste materials such as steel slag powder, tailings, waste incineration fly ash, and waste cement under autoclaving conditions. Patent CN114290504A also provides a method for producing concrete products from construction waste using cement kiln exhaust mineralization. However, existing autoclaving systems generally suffer from high temperatures and high energy consumption, while mineralization systems, at low temperatures and low flue gas concentrations, produce products that fail to meet required strength requirements. Subsequent strength support requires large amounts of aggregate and cementitious materials, which does not meet the economic requirements of modern production.

[0004] Summary of the Invention

[0005] In order to overcome the above shortcomings, the purpose of the present invention is to provide a method for preparing solid waste recycled materials with low energy consumption under a composite curing system. Based on the exothermic phenomenon of the mineralization reaction, the mineralization is coupled with the hydrothermal method, and the temperature generated by the early mineralization is utilized to reduce the heat required for the subsequent hydrothermal reaction, so as to meet the requirements of both economy and product performance.

[0006] In order to achieve the above objectives, the technical solution adopted by the present invention is: a method for preparing solid waste recycled materials with low energy consumption under a composite curing system, characterized by comprising the following steps:

[0007] S1. preparing solid waste into building material blanks;

[0008] S2. Place the building material body into a reactor and introduce flue gas to perform mineralization treatment; when the temperature in the reactor reaches a certain level, the mineralization treatment is terminated;

[0009] S3. Performing hydrothermal treatment on the mineralized building material body to obtain a building material product;

[0010] In step S2, the certain temperature reached in the reactor is the highest temperature that can be reached by self-heating during the mineralization reaction between the building material body and the flue gas.

[0011] The beneficial effects of the present invention are:

[0012] In step S2, the mineralization reaction between the flue gas and the building material body can provide part of the heat required for the molding of the building material body while consuming the carbon dioxide in the flue gas, thereby realizing the recycling of solid waste and waste gas, and achieving the purpose of saving energy and protecting the environment; then, in step S3, the building material body with a certain temperature is further subjected to hydrothermal treatment, which not only avoids the problem of low strength of the product caused by too low a mineralization treatment temperature, but also utilizes the temperature generated by the mineralization to reduce the heat required in the hydrothermal process, thereby reducing the amount of steam required to be added, reducing the cost of solid waste treatment, and achieving the requirements of both economy and high-strength performance of the product.

[0013] During the mineralization reaction, the self-heating phenomenon of the reaction between the building material body and the flue gas will cause the temperature in the reactor to continue to rise; when the mineralization reaction ends, that is, when the self-heating ends, the temperature in the reactor will reach the highest value, and then the temperature in the reactor will gradually decrease with the end of the reaction. Therefore, in order to maximize the use of the heat generated by mineralization and reduce the heat required for subsequent hydrothermal reactions, the coupling time point of mineralization and hydrothermal can be set to the time point when the self-heating of the mineralization reaction ends. In specific operations, the real-time temperature of the reactor during the mineralization reaction can be monitored. When the real-time temperature drops, it can be determined that this time point is the time point when the self-heating of the mineralization reaction ends, that is, the highest temperature of the mineralization reaction is reached in the reactor. At this time, the mineralization treatment is terminated and the hydrothermal treatment is carried out to maximize the use of the heat generated by the mineralization reaction.

[0014] Specifically, in step S3, the minimum steam heat required for the hydrothermal treatment is:

[0015] Q min ={1.1483×10 7 ×d2×(d1+d2)×L+3.1651×10 5×d3×(d1+2d2+d3)×L+(1328.7+348.78n)×[1-1273.89×m / (ρ×d1 2 ×L)]×V+4200×m×(10 3 ×w+18×a3×k3×10 3 / 74)+8.4×m×a1×10 5 -8.4×m×a1×k1×10 5 +8.4×m×a2×10 5 -8.4×m×a2×k2×10 5 +1.142×m×a3×10 6 -1.142×m×a3×k3×10 6 +1.106×m×10 6 ×a3×k3+9.51×m×10 5 ×a1×k1+1.075×m×10 6 ×a²×k²+7.3355×10 5 ×m×(1-w-a1-a2-a3)+2.515×10 5 ×m×a1×k1+1.897×10 5 ×m×a2×k2}×(T1-T0)-6.7117×10 8 ×m×a1×k1-6.1654×10 8 ×m×a2×k2-1.5384×10 9 ×m×a3×k3;

[0016] Among them, d1 is the inner diameter of the reactor, d2 is the wall thickness of the reactor, d3 is the thickness of the insulating rock wool in the reactor, L is the length of the reactor, m is the total mass of the building material body in the reactor, n is the volume percentage of carbon dioxide in the flue gas, ρ is the density of the building material product, V is the volume of the reactor, w is the moisture content of the building material body, T1 is the temperature of the hydrothermal reaction during hydrothermal treatment, T0 is the initial temperature of the reactor, a1, a2, and a3 are the mass percentages of dicalcium silicate, tricalcium silicate, and calcium hydroxide in the building material body, respectively, and k1, k2, and k3 are the reaction constants of dicalcium silicate, tricalcium silicate, and calcium hydroxide, respectively.

[0017] The inventors, combining the experience gained from long-term research and development work, have derived a theoretical calculation formula for the minimum steam heat required for hydrothermal treatment in a mineralization-coupled hydrothermal system through research and deduction of various parameters that affect steam heat. This formula can then be used to calculate the minimum steam heat required for hydrothermal treatment when treating different solid waste formulations, thereby providing a reference for the amount of steam required for hydrothermal treatment. At the same time, based on different solid waste raw material systems, the range of the calcium-silicon mass ratio in the building material blank after mineralization is limited, as well as the optimal range for the product to obtain ideal performance. In the process of experimental demonstration, when the minimum steam heat calculated by this formula is used as the actual steam heat, it can meet the requirements of high-strength performance and lowest cost of the product while balancing the maximum spontaneous heat of mineralization and the minimum steam replenishment amount for hydrothermal treatment.

[0018] Specifically, the temperature T1 of the hydrothermal reaction is 160-180° C. The temperature of the hydrothermal reaction of 160-180° C. is an empirical value obtained by the inventors through extensive research and development. Within this temperature range, the mechanical properties of the product can be maximized.

[0019] Furthermore, in step S2, the mass ratio of calcium to silicon in the building material body after mineralization treatment is 0.2 to 0.9:1. The inventors have verified through extensive research and development that when the calcium-silicon ratio of the building material body after mineralization treatment is 0.2 to 0.9:1, the calcium carbonate seeds in the building material body are relatively high, and the calcium carbonate seeds have a relatively strong promoting effect on the transformation of calcium silicate hydrate to xonotlite in the subsequent hydrothermal process. Therefore, when the calcium-silicon ratio of the building material body after mineralization treatment is 0.2 to 0.9:1, the building material body can obtain better mechanical properties under subsequent sufficient hydrothermal treatment.

[0020] Furthermore, in step S2, the mass ratio of calcium to silicon in the building material body after the mineralization treatment is 0.3 to 0.7:1. Furthermore, in step S2, the mass ratio of calcium to silicon in the building material body after the mineralization treatment is 0.4 to 0.7:1. Furthermore, in step S2, the mass ratio of calcium to silicon in the building material body after the mineralization treatment is 0.5 to 0.6:1.

[0021] Specifically, in step S1, preparing solid waste into building material blanks includes the following steps:

[0022] Mixing solid waste raw materials, adding water and stirring into a mixed slurry;

[0023] The mixed slurry is preformed to obtain a preformed body;

[0024] Forming and pressing the preformed body to obtain a building material body;

[0025] The solid waste raw materials include calcareous solid waste and silicoaluminous solid waste, and the mass ratio of the calcareous solid waste to the silicoaluminous solid waste is 5-45:15-65; the preforming treatment can adopt one of the slurry method, copying method, casting method and pressing method.

[0026] Furthermore, during the preforming process, the mixed slurry can be dehydrated by vacuuming or filter pressing. During the forming and pressing process, the preformed green body after forming and pressing needs to be pre-cured to obtain the building material green body.

[0027] Furthermore, the calcareous solid waste includes at least one of steel slag, carbide slag, sludge or waste incineration fly ash, thiourea slag, slag, waste cement, red mud, magnesium slag, phosphate slag, lithium slag and the product of sintering of calcium-containing solid waste; the siliceous alumina solid waste includes at least one of fly ash, glass tailings, large slag ash, slag, red mud, construction waste, sludge or waste incineration bottom ash, quartz sand, and silicon-containing silt.

[0028] Furthermore, the solid waste raw materials also include additional materials, and the mass ratio of the calcareous solid waste, the siliceous and aluminum-based solid waste and the additional materials is 5-45:15-65:5-15.

[0029] Specifically, the added material includes at least one of fiber, wollastonite, bentonite, vermiculite, diatomaceous earth, and aggregate. Specifically, the aggregate includes at least one of recycled aggregate and natural aggregate; the fiber includes at least one of plant fiber, mineral fiber, synthetic fiber, inorganic fiber, and recycled fiber; wherein the plant fiber includes at least one of coniferous wood fiber, hardwood fiber, cotton and linen fiber, and fruit fiber; the mineral fiber includes asbestos fiber; the synthetic fiber includes at least one of nylon fiber, nylon fiber, polyester fiber, acrylic fiber, vinylon fiber, polypropylene fiber, and PVA fiber; the inorganic fiber includes at least one of glass fiber and metal fiber; and the recycled fiber includes at least one of waste paper fiber, recycled mask fiber, and viscose fiber.

[0030] Furthermore, the water content of the mixed slurry is 65-85%, the water content of the preformed body is 40-55%, and the water content of the building material body after press forming is 25-45%.

[0031] Furthermore, the volume proportion of carbon dioxide in the flue gas is 8-99%.

[0032] Furthermore, in step S2, during the mineralization treatment, the mineralization pressure in the reactor is 0.1-2 MPa.

[0033] Furthermore, in step S3, the hydrothermal treatment includes introducing water vapor into the reactor to continuously raise the temperature in the reactor to the hydrothermal reaction temperature T1, and then performing hydrothermal curing, and the curing time is controlled within 1 to 24 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG1 is an X-ray diffraction pattern of the product of Example 1 of the present invention;

[0035] FIG2 is an X-ray diffraction pattern of the product of Example 8 of the present invention;

[0036] FIG3 is an X-ray diffraction pattern of the product of Example 9 of the present invention. DETAILED DESCRIPTION

[0037] The preferred embodiments of the present invention are described in detail below so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more precise definition of the protection scope of the present invention.

[0038] The present invention provides a method for preparing solid waste recycled materials with low energy consumption under a composite curing system, comprising the following steps:

[0039] S1. preparing solid waste into building material blanks;

[0040] S2. Place the building material body into a reactor and introduce flue gas to perform mineralization treatment; when the temperature in the reactor reaches a certain level, the mineralization treatment is terminated;

[0041] S3. Performing hydrothermal treatment on the mineralized building material body to obtain building material products.

[0042] Wherein, step S1 includes:

[0043] S11. Mix the solid waste raw materials and add water to stir into a mixed slurry. In the specific operation, the solid waste raw materials are pumped into a mixing tank for mixing. During mixing, a certain amount of water is pumped from a water tank and stirred evenly by a stirring device to form a mixed slurry. The speed of the stirring device is 200-350 r / min, and the stirring time is 10-30 minutes.

[0044] S12, preforming the mixed slurry to obtain a preformed body. The preforming process can be carried out by one of the following methods: slurry flow method, copying method, casting method, and pressing method. During the preforming process, the mixed slurry can be dehydrated by vacuuming or filter pressing to ensure that the moisture content of the preformed body meets the requirements.

[0045] Exemplarily, the specific operation of the slurry flow method combined with the vacuum pumping method is: the evenly mixed slurry is evenly flowed onto the felt belt, a water filtration area and a vacuum water filtration area are set under the felt belt, and a plurality of vacuum suction cups are set in the vacuum water filtration area. The slurry blank is first filtered in the water filtration area, and then passes through the vacuum water filtration area, and is pumped by the multiple vacuum suction cups set in the vacuum water filtration area to extract the moisture of the blank to the set moisture content.

[0046] S13, forming and pressing the preformed green body, pressing the cylinder into the green body, and pressing the green body under a press, controlling the pressure to be 5-30 MPa, and holding the pressure for 500-1200 seconds;

[0047] S14, placing the formed and pressed green body into a constant temperature and humidity room for pre-curing treatment to obtain a building material green body; wherein the pre-curing temperature is 20-60° C., the pre-curing humidity is 70-96%, and the pre-curing time is controlled at 5-15 hours.

[0048] It should be noted that in step S11, the amount of water pumped by the water tank is determined by the solid waste formulation and the type of building material product. The moisture content of the mixed slurry after water addition is generally controlled to be 65-85%. In step S12, the amount of water pumped during the moisture removal process is determined by the type of building material product. The moisture content of the preformed green body after moisture removal is generally controlled to be 40-55%. In step S13, the moisture content of the green body after press forming is 25-45%.

[0049] Step S2 specifically includes: placing the building material body after pre-curing treatment into the reactor, and making the space filling ratio of the building material body in the reactor (the filling rate in the reactor) be 5 to 60%; closing the feed port of the reactor (that is, the inlet of the building material body into the reactor), and then opening the CO2 flue gas valve on the reactor; after the flue gas is introduced, the pressure in the reactor is made to reach the mineralization pressure, and the pressure in the reactor is controlled to remain constant during the mineralization reaction; when the temperature in the reactor reaches a certain temperature, the CO2 flue gas valve is closed, and at this time, the mineralized building material body is formed in the reactor.

[0050] Step S3 specifically includes: opening the steam valve on the reactor to introduce water vapor into the reactor, and continuously raising the temperature in the reactor to T1 (i.e., the temperature of the hydrothermal reaction), and then performing hydrothermal curing, with the curing time controlled at 1 to 24 hours; after the hydrothermal curing is completed, closing the steam valve; and then, when the temperature and air pressure in the reactor reach safe values, opening the reactor and removing the building materials.

[0051] In some embodiments, the solid waste raw materials include calcareous solid waste and silicoaluminous solid waste, and the mass ratio of calcareous solid waste to silicoaluminous solid waste is 5-45:15-65.

[0052] In some embodiments, the calcareous solid waste includes at least one of steel slag, carbide slag, sludge or waste incineration fly ash, thiourea slag, slag, waste cement, red mud, magnesium slag, phosphate slag, lithium slag, and the sintering product of calcium-containing solid waste. The silicoaluminous solid waste includes at least one of fly ash, glass tailings, large slag ash, slag, red mud, construction waste, sludge or waste incineration bottom ash, quartz sand, and silicon-containing sludge.

[0053] In some embodiments, the solid waste raw material further includes an additional material, and the mass ratio of calcareous solid waste, siliceous and aluminum-based solid waste, and the additional material is 5-45:15-65:5-15.

[0054] In some embodiments, the additional material includes at least one of fiber, wollastonite, bentonite, vermiculite, diatomaceous earth, and aggregate.

[0055] Specifically, the aggregate includes at least one of recycled aggregate and natural aggregate. The fiber includes at least one of plant fiber, mineral fiber, synthetic fiber, inorganic fiber, and regenerated fiber. The plant fiber includes at least one of coniferous wood fiber, hardwood fiber, cotton and linen fiber, and fruit fiber; the mineral fiber includes asbestos fiber; the synthetic fiber includes at least one of nylon fiber, nylon fiber, polyester fiber, acrylic fiber, vinylon fiber, polypropylene fiber, and PVA fiber; the inorganic fiber includes at least one of glass fiber and metal fiber; and the regenerated fiber includes at least one of waste paper fiber, regenerated mask fiber, and viscose fiber.

[0056] In some embodiments, the flue gas is at least one of flue gases emitted from an aluminum smelter, a coal-fired power plant, a waste incineration plant, a lime kiln, a steel plant, a chemical plant, or a cement plant, and the volume proportion of carbon dioxide in the flue gas is 8 to 99%.

[0057] In some embodiments, in step S2, during the mineralization treatment, the mineralization pressure in the reactor is 0.1-2 MPa.

[0058] During the mineralization reaction, the self-heating phenomenon of the reaction between the building material body and the flue gas will cause the temperature in the reactor to continue to rise; at the moment the reaction ends, that is, when the self-heating ends, the temperature in the reactor will reach a maximum value, and then the temperature in the reactor will gradually decrease with the end of the reaction. Therefore, in order to maximize the use of the heat generated by mineralization and reduce the heat required for subsequent hydrothermal reactions, the coupling time point of mineralization and hydrothermal can be set to the time point when the self-heating of the mineralization reaction ends. In specific operations, the real-time temperature of the reactor during the mineralization reaction can be monitored. When the real-time temperature drops, the mineralization treatment can be terminated and the hydrothermal treatment can be carried out. That is, in step S2, the certain temperature reached in the reactor is the highest temperature generated by the self-heating when the building material body and the flue gas undergo the mineralization reaction.

[0059] Based on maximizing the utilization of mineralization self-heat, the inventors combined the experience gained from long-term research and development work, and through the study and deduction of various parameters affecting steam heat, derived a theoretical calculation formula for the minimum steam heat required for hydrothermal treatment in a mineralization-coupled hydrothermal system. This formula can then be used to calculate the minimum steam heat required for hydrothermal treatment when treating different solid waste formulations, providing a reference for the amount of steam required for hydrothermal treatment. The theoretical calculation formula for the minimum steam heat required for hydrothermal treatment is as follows:

[0060] Q min ={1.1483×10 7 ×d2×(d1+d2)×L+3.1651×10 5 ×d3×(d1+2d2+d3)×L+(1328.7+348.78n)×[1-1273.89×m / (ρ×d1 2 ×L)]×V+4200×m×(10 3 ×w+18×a3×k3×10 3 / 74)+8.4×m×a1×10 5 -8.4×m×a1×k1×10 5 +8.4×m×a2×10 5 -8.4×m×a2×k2×10 5 +1.142×m×a3×10 6 -1.142×m×a3×k3×10 6 +1.106×m×10 6 ×a3×k3+9.51×m×10 5 ×a1×k1+1.075×m×10 6 ×a²×k²+7.3355×10 5 ×m×(1-w-a1-a2-a3)+2.515×10 5 ×m×a1×k1+1.897×10 5 ×m×a2×k2}×(T1-T0)-6.7117×10 8 ×m×a1×k1-6.1654×10 8 ×m×a2×k2-1.5384×10 9 ×m×a3×k3;

[0061] Among them, Q minis the minimum steam heat (unit: J), d1 is the inner diameter of the reactor (unit: m), d2 is the wall thickness of the reactor (unit: m), d3 is the thickness of the thermal insulation rock wool in the reactor (unit: m), L is the length of the reactor (unit: m), m is the total mass of the building material blank in the reactor (unit: t), n is the volume fraction of carbon dioxide in the flue gas, ρ is the density of the building material product (unit: kg / m 3 ), V is the volume of the reactor (unit: m 3 ), w is the moisture content of the building material body, T1 is the temperature of the hydrothermal reaction during hydrothermal treatment (in °C), T0 is the initial temperature of the reactor (in °C, usually room temperature, such as 20 °C), a1, a2, and a3 are the mass proportions of dicalcium silicate, tricalcium silicate, and calcium hydroxide in the building material body, respectively, and k1, k2, and k3 are the reaction constants of dicalcium silicate, tricalcium silicate, and calcium hydroxide, respectively. When calculating, substitute the values ​​of the provided units for each parameter into the formula and perform the numerical calculation (i.e., no unit operations are involved in the calculation process).

[0062] In this formula, d1, d2, d3, L, and V take into account the effect of the reaction vessel on self-heating; m, w, and ρ take into account the effect of the performance of building materials on self-heating; a1, a2, a3 and k1, k2, and k3 take into account the effect of different contents of dicalcium silicate, tricalcium silicate, and calcium hydroxide in different solid waste formulas (different solid waste formulas generate different amounts of heat in the mineralization reaction) on self-heating; T1 and T0 take into account the effect of temperature on self-heating. Based on this formula, the minimum steam heat required to be supplemented after mineralization under each solid waste formula can be obtained. The steam heat supplemented in actual production should not be lower than the minimum steam heat to ensure the performance of the final product. Usually, in actual production, the minimum steam heat calculated according to this formula can be used to supplement steam, thereby reducing production costs in the dimension of minimizing steam costs, while also avoiding excessive steam input that affects product performance.

[0063] In this formula, the temperature T1 of the hydrothermal reaction is set to 160-180°C. This temperature range is the optimal temperature for the hydrothermal reaction verified by the inventors through a lot of research and development. Within this temperature range, the mechanical properties of the final building materials products are the best. At the same time, the inventors conducted a lot of research and development verification on the solid waste formula for producing the building materials products of the present invention, and finally found that when the calcium-silicon ratio in the mineralized product after the mineralization reaction is 0.2-0.9:1, preferably 0.3-0.7:1, more preferably 0.4-0.7:1, and further preferably 0.5-0.6:1, the calcium carbonate seeds in the mineralized product after mineralization treatment are relatively the highest, and the calcium carbonate seeds have the strongest promoting effect on the transformation of hydrated calcium silicate to hard notatite in the subsequent hydrothermal process, so that the mineralized product after the mineralization reaction can obtain sufficient hydrothermal reaction, so that the final building materials products can obtain ideal mechanical properties.

[0064] Example 1

[0065] Steel slag from steel mills, carbide slag from power plants, and waste cement from cement plants served as calcareous solid wastes; glass tailings from glass factories and fly ash from thermal power plants served as siliceous and aluminous solid wastes; and flue gas from waste incineration plants served as mineralized flue gas. Commercially available softwood fiber, hardwood fiber, bentonite, and vermiculite served as additional materials. It should be noted that the average particle size of the steel slag, carbide slag, waste cement, glass tailings, and fly ash used in the following examples ranged from 200 to 300 mesh, the average particle size of the bentonite was approximately 300 mesh, and the average particle size of the vermiculite was approximately 325 mesh.

[0066] X-ray fluorescence (XRF) analysis was then used to analyze the composition of steel slag, carbide slag, glass tailings, fly ash, waste cement, and mineralized flue gas. The results are shown in Tables 1 to 6. It should be noted that while XRF can only indicate the composition of each element, and displays it as oxides, it cannot represent the actual phase composition of the material. For example, while calcium appears as calcium oxide in XRF, it can actually exist as dicalcium silicate, tricalcium silicate, calcium hydroxide, etc., depending on the actual composition of the material.

[0067] Table 1 Chemical composition of steel slag (mass fraction)

[0068] Table 2 Chemical composition of carbide slag (mass fraction)

[0069] Table 3 Chemical composition of glass tailings (mass fraction)

[0070] Table 4 Chemical composition of fly ash (mass fraction)

[0071] Table 5 Chemical composition of waste cement (mass fraction)

[0072] Table 6 Composition of flue gas from waste incineration plants (volume fraction)

[0073] Reactor parameters: inner diameter d1 is 2m, wall thickness d2 is 0.01m, insulation rock wool thickness d3 is 0.1m, reactor length L is 31m, reactor volume V is 97.34m 3 .

[0074] Building material product parameters: When entering the kettle, the moisture content of the building material body w is about 27%, and the density ρ is 1400kg / m 3Each kettle is equipped with 12 carts, each cart is loaded with 114 products, the product size is 2440mm×1220mm×8mm, the total mass m of the building material body in each kettle is 45.61t, and the filling rate in the kettle is 33.5%.

[0075] Solid waste parameters: The reaction constant k1 of dicalcium silicate is 0.5, the reaction constant k2 of tricalcium silicate is 0.5, and the reaction constant k3 of calcium hydroxide is 0.6, where:

[0076] In the steel slag, the content of dicalcium silicate is 52.14% and the content of tricalcium silicate is 17.92% by mass;

[0077] In carbide slag, the calcium hydroxide content is 93.7% by mass;

[0078] In the waste cement, by mass percentage, the content of dicalcium silicate is 49.18%, the content of tricalcium silicate is 15.15%, and the content of calcium hydroxide is 5.48%.

[0079] The volume proportion of carbon dioxide in the flue gas is 73%, the initial temperature T0 in the kettle is 20°C, and the hydrothermal reaction temperature T1 is 180°C.

[0080] Then, the mineralization coupled hydrothermal method of the present invention is used to prepare building materials. The preparation steps are as follows:

[0081] (1) Carbide slag, steel slag, glass tailings, and coniferous wood fiber are mixed uniformly in a ratio of 25:32:35:8, and measured water is added to the mixture to control the moisture content of the mixed slurry to 80%;

[0082] (2) The mixed slurry is preformed by a slurry flow method, and a certain amount of water is removed by vacuuming. At the same time, the slurry surface is smoothed with a flat shovel. At this time, the green body is initially formed to form a preformed green body. After vacuuming, the moisture content in the preformed green body is about 40%;

[0083] (3) The preformed green body is formed and pressed, the forming pressure is controlled at 20 MPa, the holding time is 900 s, and the moisture content of the green body after pressing is about 27%;

[0084] (4) placing the formed and pressed green body into a constant temperature and humidity chamber for pre-curing at a temperature of 60°C and a humidity of 96% for 8 hours;

[0085] (5) Place the pre-cured green body into the reactor, and make the green body filling ratio in the reactor be 33.5%. Close the feed port of the reactor, open the CO2 flue gas valve, and after the flue gas is introduced, make the pressure in the reactor reach 0.6 MPa. Control the pressure in the reactor to remain constant during the reaction process. When the temperature rises to 121°C, close the CO2 flue gas valve.

[0086] (6) Open the steam valve and introduce 2010.71 kg of steam until the pressure in the kettle reaches 1.01 MPa. Then, raise the temperature to 180°C and perform hydrothermal curing. Continue the reaction for 10 hours and then close the steam valve.

[0087] (7) When the temperature inside the kettle reaches below 80°C, open the kettle and take out the sample.

[0088] It should be noted that, during the above preparation process, the temperature in the kettle reaches 121°C, which is the maximum value of heat release when the mineralization reaction is carried out according to the above solid waste formula, after which the temperature in the kettle begins to drop.

[0089] Under this solid waste formulation system, the self-heating of mineralization can raise the kettle temperature to 121°C. Accordingly, the minimum steam heat required can be calculated according to the theoretical calculation formula of minimum steam heat. When using the theoretical calculation formula of minimum steam heat, a1, a2, and a3 must first be calculated according to the solid waste formulation. In the solid waste formulation of this embodiment, only steel slag contains dicalcium silicate and tricalcium silicate, and carbide slag contains calcium hydroxide. Accordingly,

[0090] a1=(1-27%)×52.14%×32 / (25+32+35+8), where 27% is the moisture content of the building material body, 52.14% is the mass proportion of dicalcium silicate in steel slag, and 32 / (25+32+35+8) is the mass proportion of steel slag in the building material body.

[0091] Similarly, a2 = (1-27%) × 17.92% × 32 / (25+32+35+8), where 27% is the moisture content of the building material body, 17.92% is the mass proportion of tricalcium silicate in steel slag, and 32 / (25+32+35+8) is the mass proportion of steel slag in the building material body.

[0092] a3 = (1-27%) × 93.7% × 25 / (25+32+35+8). Here, 27% is the moisture content of the building material, 93.7% is the mass percentage of tricalcium silicate in the carbide slag, and 25 / (25+32+35+8) is the mass percentage of the carbide slag in the building material.

[0093] After calculating a1, a2, and a3, the minimum steam heat required to be added can be calculated as 5.63×10 6 KJ, and then the minimum steam amount to be introduced (i.e. the actual steam amount in this embodiment) is converted into 2010.71 kg according to the minimum steam heat.

[0094] The steam used in this example was heated by firing a boiler. The steam temperature was controlled by adjusting the boiler firing time so that the steam provided approximately 2800 kJ / kg of heat when entering the kettle. It should be noted that in the following examples, the steam heat was converted into the corresponding steam volume based on the heat of 2800 kJ / kg.

[0095] When calculating the cost, since the green body moisture content is about 27%, and there are differences in the moisture content of each raw material, for the convenience of calculation, the present embodiment uniformly does not count the raw material moisture content. Therefore, when costing, it is necessary to uniformly multiply by (1-27%) to exclude the moisture in the green body. According to the commercially available steam average price of 280 yuan / ton, each kettle needs to be supplemented with 563.00 yuan of steam. For the convenience of intuitively comparing the finished products of each embodiment, according to commercially available calcium carbide slag 120 yuan / ton, glass tailings 90 yuan / ton, steel slag 200 yuan / ton, and softwood fiber 5700 yuan / ton, the cost of each kettle product (excluding machine operation, labor, and water) is 19924.22 yuan, that is, a building material product cost of 14.56 yuan.

[0096] Example 2

[0097] The difference between Example 2 and Example 1 is that the solid waste formulation is different and the amount of steam introduced during the hydrothermal treatment is different.

[0098] Specifically, the solid waste formula in this embodiment is: carbide slag, steel slag, fly ash, and coniferous wood fiber are evenly mixed in a ratio of 20:22:50:8.

[0099] Since the self-heating of mineralization can raise the kettle temperature to 99.86℃ under this solid waste formulation system, the minimum steam heat required to be supplemented is calculated to be 7.47×10 6 KJ, and then according to the minimum steam heat conversion, the minimum steam amount to be introduced is 2667.86kg. Therefore, in this embodiment, during the hydrothermal treatment, the actual steam amount introduced is 2667.86kg.

[0100] Based on the average market price of 280 yuan / ton for steam, each kettle requires 747.00 yuan of steam replenishment. Based on market prices of 120 yuan / ton for calcium carbide slag, 120 yuan / ton for fly ash, 200 yuan / ton for steel slag, and 5,700 yuan / ton for softwood fiber, the cost of each kettle product (excluding machine operation, labor, and water) is 20,191.46 yuan, or 14.76 yuan per unit of building material.

[0101] Example 3

[0102] The difference between Example 3 and Example 1 is that the solid waste formulation is different and the amount of steam introduced during the hydrothermal treatment is different. Specifically, the solid waste formulation in this example is: carbide slag, waste cement, glass tailings, and coniferous wood fiber are evenly mixed in a ratio of 25:30:37:8.

[0103] Since the self-heating of mineralization can raise the kettle temperature to 122.59℃ under this solid waste formulation system, the minimum steam heat required is calculated to be 5.50×10 6 KJ, and then the minimum steam quantity to be introduced is converted into 1964.29kg according to the minimum steam heat. Therefore, in this embodiment, the actual steam quantity introduced during the hydrothermal treatment is 1964.29kg.

[0104] It should be noted that since both carbide slag and waste cement contain calcium hydroxide in the solid waste formulation, the waste cement contains 49.18% dicalcium silicate, 15.15% tricalcium silicate, and 5.48% calcium hydroxide. Therefore, a3 in this embodiment is the sum of the calcium hydroxide contents in the carbide slag and waste cement.

[0105] Based on the average market price of 280 yuan / ton for steam, each kettle requires 550 yuan of steam replenishment. Based on the market prices of 120 yuan / ton for calcium carbide slag, 90 yuan / ton for glass tailings, 350 yuan / ton for waste cement, and 5,700 yuan / ton for softwood fiber, the cost of each kettle product (excluding machine operation, labor, and water) is 21,336.26 yuan, or 15.60 yuan per unit of building material.

[0106] Example 4

[0107] The difference between Example 4 and Example 1 is that the amount of steam introduced during the hydrothermal treatment is different.

[0108] Specifically, during the hydrothermal treatment, the amount of steam introduced is 2500 kg, and accordingly, the steam heat generated is 7.0×10 6 KJ.

[0109] Example 5

[0110] The difference between Example 5 and Example 3 is that the amount of steam introduced during the hydrothermal treatment is different.

[0111] Specifically, during the hydrothermal treatment, the amount of steam introduced is 2500 kg, and accordingly, the steam heat generated is 7.0×10 6 KJ.

[0112] Example 6

[0113] The difference between Example 6 and Example 1 is that the ratio of the solid waste formula is different.

[0114] Specifically, the solid waste formula in this embodiment is: carbide slag, steel slag, glass tailings, and coniferous wood fiber are evenly mixed in a ratio of 22:30:40:8.

[0115] Example 7

[0116] The difference between Example 7 and Example 1 is that the ratio of the solid waste formula is different.

[0117] Specifically, the solid waste formula in this embodiment is: carbide slag, steel slag, glass tailings, and coniferous wood fiber are evenly mixed in a ratio of 25:35:32:8.

[0118] Example 8

[0119] The difference between Example 8 and Example 1 is that the ratio of the solid waste formula is different.

[0120] Specifically, the solid waste formula in this embodiment is: carbide slag, steel slag, glass tailings, and coniferous wood fiber are evenly mixed in a ratio of 30:40:22:8.

[0121] Example 9

[0122] The difference between Example 9 and Example 1 is that the ratio of the solid waste formula is different.

[0123] Specifically, the solid waste formula in this embodiment is: carbide slag, steel slag, glass tailings, and coniferous wood fiber are evenly mixed in a ratio of 10:12:70:8.

[0124] Example 10

[0125] The difference between Example 10 and Example 2 is that the ratio of the solid waste formula is different.

[0126] Specifically, the solid waste formula in this embodiment is: carbide slag, steel slag, fly ash, and coniferous wood fiber are evenly mixed in a ratio of 20:18:54:8.

[0127] Example 11

[0128] The difference between Example 11 and Example 2 is that the ratio of the solid waste formula is different.

[0129] Specifically, the solid waste formula in this embodiment is: carbide slag, steel slag, fly ash, and coniferous wood fiber are evenly mixed in a ratio of 25:20:47:8.

[0130] Example 12

[0131] The difference between Example 12 and Example 2 is that the ratio of the solid waste formula is different.

[0132] Specifically, the solid waste formula in this embodiment is: carbide slag, steel slag, fly ash, and coniferous wood fiber are evenly mixed in a ratio of 30:30:32:8.

[0133] Example 13

[0134] The difference between Example 13 and Example 2 is that the ratio of the solid waste formula is different.

[0135] Specifically, the solid waste formula in this embodiment is: carbide slag, steel slag, fly ash, and coniferous wood fiber are evenly mixed in a ratio of 10:10:72:8.

[0136] Example 14

[0137] The difference between Example 14 and Example 3 is that the ratio of the solid waste formula is different.

[0138] Specifically, the solid waste formula in this embodiment is: carbide slag, waste cement, glass tailings, and coniferous wood fiber are evenly mixed in a ratio of 30:30:32:8.

[0139] Example 15

[0140] The difference between Example 15 and Example 3 is that the ratio of the solid waste formula is different.

[0141] Specifically, the solid waste formula in this embodiment is: carbide slag, waste cement, glass tailings, and coniferous wood fiber are evenly mixed in a ratio of 22:30:40:8.

[0142] Example 16

[0143] The difference between Example 16 and Example 3 is that the ratio of the solid waste formula is different.

[0144] Specifically, the solid waste formula in this embodiment is: carbide slag, waste cement, glass tailings, and coniferous wood fiber are evenly mixed in a ratio of 30:40:22:8.

[0145] Example 17

[0146] The difference between Example 17 and Example 3 is that the ratio of the solid waste formula is different.

[0147] Specifically, the solid waste formula in this embodiment is: carbide slag, waste cement, glass tailings, and coniferous wood fiber are evenly mixed in a ratio of 10:15:67:8.

[0148] Example 18

[0149] The difference between Example 18 and Example 1 is that the ratio of the solid waste formula is different.

[0150] Specifically, the solid waste formula in this embodiment is: carbide slag, steel slag, glass tailings, and coniferous wood fiber are evenly mixed in a ratio of 25:33:36:6.

[0151] Example 19

[0152] The difference between Example 19 and Example 1 is that the added materials in the solid waste formula are different.

[0153] Specifically, the solid waste formula in this embodiment is: carbide slag, steel slag, glass tailings, and hardwood fiber are evenly mixed in a ratio of 25:32:35:8.

[0154] Example 20

[0155] The difference between Example 20 and Example 1 is that the added materials in the solid waste formula are different.

[0156] Specifically, the solid waste formula in this embodiment is: carbide slag, steel slag, glass tailings, and bentonite are evenly mixed in a ratio of 25:32:35:8.

[0157] It should be noted that the bentonite used is specially used for papermaking, and the market price is about 1,500 yuan / ton.

[0158] Example 21

[0159] The difference between Example 21 and Example 1 is that the added materials in the solid waste formula are different.

[0160] Specifically, the solid waste formula in this embodiment is: carbide slag, steel slag, glass tailings, and vermiculite are evenly mixed in a ratio of 25:32:35:8.

[0161] It should be noted that the vermiculite used is special vermiculite for papermaking, and the market price is about 880 yuan / ton.

[0162] Comparative Example 1

[0163] The difference between Comparative Example 1 and Example 1 is that the amount of steam introduced during the hydrothermal treatment is different.

[0164] Specifically, during the hydrothermal treatment, the amount of steam introduced was 1428.57 kg, and accordingly, the steam heat generated was 4.0 × 10 6 KJ.

[0165] Comparative Example 2

[0166] The difference between Comparative Example 2 and Example 1 is that the amount of steam introduced during the hydrothermal treatment is different.

[0167] Specifically, during the hydrothermal treatment, the amount of steam introduced was 3035.7 kg, and the steam heat generated was 8.5×10 6 KJ.

[0168] Comparative Example 3

[0169] The difference between Comparative Example 3 and Example 3 is that the amount of steam introduced during the hydrothermal treatment is different.

[0170] Specifically, during the hydrothermal treatment, the amount of steam introduced was 3035.71 kg, and the steam heat generated was 8.5×10 6 KJ.

[0171] Comparative Example 4

[0172] The difference between Comparative Example 4 and Example 1 is that the ratio of the solid waste formula is different.

[0173] Specifically, the solid waste formula in this embodiment is: carbide slag, steel slag, glass tailings, and coniferous wood fiber are evenly mixed in a ratio of 70:10:12:8.

[0174] Comparative Example 5

[0175] The difference between Comparative Example 5 and Example 1 is that the ratio of the solid waste formula is different.

[0176] Specifically, the solid waste formula in this embodiment is: carbide slag, steel slag, glass tailings, and coniferous wood fiber are evenly mixed in a ratio of 22:28:48:2.

[0177] In the above examples and comparative examples, except for Example 20, the density of the product was reduced to 1200 kg / m due to the low density of bentonite. 3 In addition, for the product systems of other embodiments and comparative examples, the fluctuation of material ratio (without adding density-reducing material) will cause the product density to be between 1350 and 1450 kg / m 3 The thickness of the product fluctuates between 8±0.3mm, but the density and thickness fluctuations have a great influence on the minimum steam heat Q min The influence of can be ignored, therefore, except for Example 20, the product density of other examples and comparative examples is based on the average value of 1400 kg / m 3 count.

[0178] Test example

[0179] The building materials prepared in Examples 1 to 21 and Comparative Examples 1 to 5 were subjected to performance tests, and the test results are shown in Table 7, wherein the flexural strength is in accordance with GB / T 7019-2014; the mass of the mineralized product is its mass at 105°C; the prices of raw materials and steam in the cost calculation are calculated according to the average market price, wherein carbide slag is 120 yuan / ton, fly ash is 120 yuan / ton, cement is 350 yuan / ton, steel slag is 200 yuan / ton, glass tailings is 90 yuan / ton, fly ash is 120 yuan / ton, steam is 280 yuan / ton, coniferous wood fiber is 5700 yuan / ton, broadleaf wood fiber is 4700 yuan / ton, bentonite is 1500 yuan / ton, and vermiculite is 880 yuan / ton.

[0180] Table 7 Test results of Examples 1 to 15 and Comparative Examples 1 to 5

[0181] (1) Analysis of the data of Example 1, Example 4 and Comparative Example 1 and Comparative Example 2 shows that:

[0182] Example 1 was carried out under the ratio of carbide slag, steel slag, glass tailings, and coniferous wood fiber of 25:32:35:8. Under this solid waste formulation system, the temperature in the kettle reached 121°C at the end of mineralization. Based on the theoretical calculation formula of the minimum steam heat proposed in the present invention, the minimum steam heat required to be introduced was calculated to be 5.63×10 6 KJ, that is, the actual amount of steam introduced during hydrothermal treatment is 2010.71 kg (calculated based on 1 kg of steam providing 2800 KJ of heat), and the calcium-silicon ratio in the building material body after mineralization treatment is 0.58, and the flexural strength of the product reaches 21.27 MPa.

[0183] Example 4, Comparative Example 1, Comparative Example 2 and Example 1 all use the same solid waste formulation system, the difference being that the actual amount of steam introduced during the hydrothermal treatment is not calculated according to the minimum steam heat conversion proposed in the present invention. Among them, the actual amount of steam introduced in Example 4 (2500kg) is greater than the actual amount of steam introduced in Example 1 (2010.71kg). Compared with the product in Example 1, the flexural strength of the product of Example 4 does not fluctuate significantly. However, due to the increase in the amount of steam, the cost of the product increases. Therefore, based on the consideration of production economy, the amount of steam introduced during hydrothermal treatment should be controlled as close as possible to the minimum steam amount calculated theoretically; the actual amount of steam introduced in Comparative Example 1 (1428.57kg) is much smaller than the minimum steam amount obtained by calculation, resulting in the final hydrothermal reaction temperature not reaching 180°C, the hydrothermal reaction is insufficient, and the strength of the product of Comparative Example 1 is reduced to 14.72Mpa; the actual amount of steam introduced in Comparative Example 2 (3035.71kg) is much larger than the minimum steam amount obtained by calculation, resulting in the final hydrothermal reaction temperature being too high, the external fiber of the product being burned, its bonding force to the solid waste raw materials and its skeleton function failing, and the product cracking.

[0184] Therefore, according to the positive and negative deviation experiments on the theoretical minimum steam heat in Example 1, Example 4, Comparative Example 1, and Comparative Example 2, too much or too little steam will lead to problems such as insufficient product strength, increased costs, and damage to the product.

[0185] (2) Analysis of the data of Example 1, Example 3, Example 5, and Comparative Example 3 shows that:

[0186] Compared to Example 1, Examples 3, 5, and Comparative Example 3 adjusted the solid waste formulation to a ratio of 25:30:37:8 for carbide slag, waste cement, glass tailings, and softwood fiber. The accuracy and universality of the minimum steam quantity theoretical formula were verified based on this adjusted solid waste formulation.

[0187] In Example 3, the calcium-silicon ratio of the building material body after mineralization treatment was 0.53, and the flexural strength of the product reached 23.13 MPa. Compared with Example 1, the strength of the product of Example 3 was improved. This is because Example 3 replaced steel slag with waste cement. The mineralization activity of calcium silicate in cement is better than that of steel slag. In addition, some of the calcium in steel slag exists as free calcium oxide, which has a negative impact on the strength of the product.

[0188] Under the solid waste formulation system of Example 3, Example 5 and Comparative Example 3, the temperature in the kettle at the end of mineralization can reach 122.59°C. Based on the theoretical calculation formula of the minimum steam heat proposed in the present invention, the minimum steam heat required to be introduced is calculated to be 5.5×10 6KJ, i.e., the minimum steam flow rate is 1964.29 kg. The actual steam flow rate in Example 3 is 1964.29 kg, in Example 5 it is 2500 kg (slightly greater than the minimum steam flow rate), and in Comparative Example 3 it is 3035.71 kg (much greater than the minimum steam flow rate). Compared to Example 3, Example 5 exhibits less strength fluctuation in the product, but at the expense of increased cost. The product in Comparative Example 3 exhibits cracking.

[0189] Therefore, through Example 1, Example 3, Example 5, and Comparative Example 3, it can be verified that the theoretical minimum steam heat algorithm of the present invention is a scientific and accurate algorithm that is suitable for achieving minimum steam cost and optimal mechanical properties under different solid waste formulation systems. (3) Analysis of the data of Example 1, Example 6, Example 7, Example 8, and Example 9 shows that:

[0190] Compared with Example 1, Example 6 reduced the amount of carbide slag by 3% and the amount of steel slag by 2%, and added 5% of glass tailings, resulting in a calcium-silicon ratio of 0.47 in the building material body after the mineralization reaction. Compared with Example 1, Example 7 increased the amount of steel slag by 3% and reduced the amount of glass tailings by 3%, resulting in a calcium-silicon ratio of 0.65 in the building material body after the mineralization reaction. On this basis, although the flexural strength of the products of Examples 6 and 7 decreased compared with Example 1, it still remained above 17 MPa.

[0191] Furthermore, Examples 8 and 9 further adjusted the calcium-silicon ratio. In Example 8, the ratio of carbide slag: steel slag: glass tailings: coniferous wood fiber was 30:40:22:8, and the calcium-silicon ratio further increased to 1.03. In Example 9, the ratio of carbide slag: steel slag: glass tailings: coniferous wood fiber was 10:12:70:8, and the calcium-silicon ratio was reduced to 0.12. The flexural strength of the two products was reduced to 13.17 MPa and 12.38 MPa, respectively. It can be seen that both too large and too small calcium-silicon ratios are not conducive to the strength of the product.

[0192] As shown in Figure 1-3, "C" represents calcite-type calcium carbonate (CaCO3), "Q" represents quartz (SiO2), and "T" represents tobermorite (Ca5(Si6O 18 H2)·H2O), "H" represents CSH gel (Ca2SiO4·3H2O), and the internal crystalline structures of the three products of Example 1, Example 8, and Example 9 were characterized by X-ray diffraction spectroscopy, so as to analyze the different strength supports of the products caused by different calcium-silicon ratios from a microscopic perspective.

[0193] Among them, as shown in Figure 1, the calcium-silicon ratio (0.58) of Example 1 after mineralization is within the preferred calcium-silicon ratio range (0.2-0.9) proposed in the present invention, and the internal structure of its product is mainly composed of calcite-type calcium carbonate, tobermorite and remaining silica gel. No intermediate phases such as hydrated calcium silicate are found in the structure, indicating that when the hydrothermal reaction is carried out at this calcium-silicon ratio, it can promote the full transformation of CSH gel (amorphous hydrated calcium silicate gel) to hard calcium silicate. Ultimately, silica gel is used as a skeleton to wrap and link calcium carbonate crystals, and mullite is used as a reinforcing crystal to synergistically promote the excellent performance of the product;

[0194] In Example 8, the calcium-silicon ratio after mineralization was 1.03, indicating an excess of calcium. After mineralization, a relatively large amount of calcium still reacted hydrothermally with silicon. This imbalance in the calcium-silicon ratio affected the transformation of the CSH gel into xonotlite. As can be seen from the X-ray diffraction pattern shown in Figure 2, the product's interior consisted of calcite-type calcium carbonate and a large amount of amorphous calcium silicate hydrate. Due to incomplete transformation of the crystalline phase, or the transition of some mullite to an amorphous phase or other phase after formation, the strength of the product decreased. In Example 9, the calcium-silicon ratio after mineralization was 0.12. Due to the lack of calcium raw material, there was less binding with silicon in the back-end hydrothermal reaction. As can be seen from the X-ray diffraction pattern in Figure 3, the product's interior was primarily composed of calcite-type calcium carbonate, a large amount of calcium silicate hydrate, and remaining silicon dioxide, resulting in a strength of only 12.38 MPa compared to Example 7. Furthermore, due to the significantly reduced content of mineralizable matter in Example 9, the carbon fixation rate was only 5.6%.

[0195] Therefore, through Examples 1, 6, 7, 8, and 9, it can be verified that when the calcium-silicon ratio after mineralization treatment proposed by the present invention is between 0.2 and 0.9, the sufficiency of subsequent hydrothermal treatment can be guaranteed, so that the product can obtain better mechanical properties; and when the calcium-silicon ratio exceeds the range of 0.2 to 0.9, the strength of the product decreases significantly.

[0196] (4) Analysis of the data of Examples 2, 10, 11, 12, and 13 and analysis of the data of Examples 3, 14, 15, 16, and 17 revealed that:

[0197] Compared to Example 1, Example 2, Example 10, Example 11, Example 12, and Example 13 replaced glass tailings with fly ash, and Example 2, Example 10, Example 11, Example 12, and Example 13 adjusted the ratio of carbide slag, steel slag, and fly ash. The calcium-silicon ratio of the building material body after mineralization in Example 2 was 0.54, and the flexural strength of the product reached 19.03 MPa. Example 10, based on Example 2, reduced the steel slag content by 4% and increased it to fly ash, resulting in a decrease in the calcium-silicon ratio after mineralization to 0.47, while the flexural strength of the product decreased to 17.94 MPa. Example 11, based on Example 2, increased the carbide slag content, resulting in an increase in the calcium-silicon ratio after mineralization to 0.63, while the flexural strength of the product decreased to 16.15 MPa. Furthermore, in Example 12, steel slag and carbide slag replaced part of the fly ash, so that the calcium-silicon ratio of the mineralized building material body increased to 1.11, while in Example 13, fly ash replaced part of the carbide slag and steel slag, so that the calcium-silicon ratio of the mineralized building material body decreased to 0.19. The flexural strength of both showed a significant decrease, decreasing to 13.37 MPa and 12.33 MPa, respectively.

[0198] Compared with Example 1, Example 3, Example 14, Example 15, Example 16, and Example 17 adjust steel slag to waste cement, and Example 3, Example 14, Example 15, Example 16, and Example 17 adjust the ratio of carbide slag, waste cement, and glass tailings. Among them, the calcium-silicon ratio of the building material body after mineralization treatment in Example 3 is 0.53, and the flexural strength of the product reaches 23.13Mpa. On the basis of Example 3, Example 14 increases the dosage of carbide slag, resulting in the calcium-silicon ratio after mineralization being increased to 0.67, while the flexural strength of the product is reduced to 19.87Mpa. On the basis of Example 3, Example 15 reduces the dosage of carbide slag and adds it to the glass tailings, resulting in the calcium-silicon ratio after mineralization being reduced to 0.47, and the flexural strength of the product is reduced to 18.89Mpa. Furthermore, in Example 16 and Example 17, the calcium-silicon ratio after mineralization was adjusted to 1.03 and 0.14 respectively (outside the range of 0.2 to 0.9), and the flexural strength of the products decreased significantly, falling to 11.72 MPa and 12.15 MPa respectively.

[0199] Therefore, through the above vertical reference and horizontal comparison (comparison of Examples 1, 6, 7, 8, and 9, comparison of Examples 2, 10, 11, 12, and 13, and comparison of Examples 3, 14, 15, 16, and 17), it can be seen that when the calcium-silicon ratio of the mineralized product is between 0.2 and 0.9, the product can exhibit better mechanical properties under different solid waste formulation systems; and when the calcium-silicon ratio exceeds the range of 0.2 to 0.9, the strength of the product decreases significantly. Therefore, a calcium-silicon ratio of the mineralized product between 0.2 and 0.9 helps the product obtain relatively ideal mechanical properties.

[0200] In addition, the carbon fixation rates of Examples 13 and 17 were significantly reduced due to the reduction in the content of mineralizable substances. (5) Analysis of the data of Examples 18, 19, 20, 21 and Comparative Example 5 shows that:

[0201] Compared to Example 1, Example 18 reduced the softwood fiber content to 6%. Although this reduced costs, the product's flexural strength also dropped to 17.37 MPa. Comparative Example 5 further reduced the fiber content to 2%. Although the calcium-silicon ratio of the mineralized product remained between 0.3 and 0.7, and the product cost also decreased significantly, the product's flexural strength also dropped significantly to 9.52 MPa. Example 19 changed the type of added material, replacing the softwood fiber with hardwood fiber. Its flexural strength dropped to 16.33 MPa, which is still relatively ideal, indicating that different fiber types can affect product performance to a certain extent.

[0202] In Example 20, the external material is replaced with bentonite, thereby increasing the internal porosity of the product, further improving the mineralization efficiency and mineralization depth, and its cost is reduced to 5.49 yuan / piece, and the carbon fixation rate can reach 12.9%. However, due to the lack of fiber, the binding force and skeleton effect on the solid waste raw materials are reduced, resulting in the product's flexural strength as low as 14.87Mpa. However, due to the increase in internal porosity, the apparent density of the product is increased from 1400kg / m 3 Reduced to 1200kg / m 3 The application scenarios of the plate after density reduction are expanded, and for the actual production line, the materials used are further reduced under the same production scale and output, and the total weight of materials required to produce one batch of plate is reduced to 39.09 tons. At the same time, compared with Example 1, the supplementary steam heat of Example 20 is reduced from 5.63×10 6 KJ dropped to 5.04×10 6 KJ, the cost of each product dropped to 5.49 yuan.

[0203] In Example 21, the additional material is replaced with vermiculite, and the cost of the product is further reduced to only 5.18 yuan per piece, while the flexural strength of the product is maintained above 12 MPa. Based on the fact that the strength of the product is still comparable to that of ordinary products on the market and the cost has obvious advantages, it has excellent market prospects.

[0204] Therefore, the type and amount of added materials significantly impact the flexural strength of the product, and product performance can be improved with increasing cost. The extensive research and development conducted by this invention can quantify the approximate corresponding trends in products with different performance and prices, thereby providing corresponding guidance for product positioning, product demand, and production.

[0205] The above embodiments are only for illustrating the technical concept and features of the present invention. Its purpose is to enable people familiar with this technology to understand the content of the present invention and implement it. It cannot be used to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing solid waste recycled materials with low energy consumption under a composite curing system, characterized in that: The steps include: S1. preparing solid waste into building material blanks; S2, placing the building material blank into a reactor and introducing flue gas for mineralization treatment; when the temperature in the reactor reaches a certain level, the mineralization treatment is terminated; S3, performing hydrothermal treatment on the building material blank after the mineralization treatment to obtain a building material product; In step S2, the certain temperature reached in the reactor is the highest temperature reached by self-heating during the mineralization reaction between the building material blank and the flue gas.

2. The method for preparing solid waste recycled materials with low energy consumption under the composite curing system according to claim 1, characterized in that: In step S3, the minimum steam heat required for hydrothermal treatment is: Q min ={1.1483×10 7 ×d2×(d1+d2)×L+3.1651×10 5 ×d3×(d1+2d2+d3)×L+(1328.7+348.78n)×[1-1273.89 ×m / (ρ×d1 2 ×L)]×V+4200×m×(10 3 ×w+18×a3×k3×10 3 / 74)+8.4×m×a1×10 5 -8.4×m×a1×k1×10 5 +8.4×m×a2×10 5 -8.4×m×a2×k2×10 5 +1.142×m×a3×10 6 -1.142×m×a3×k3×10 6 +1.106×m×10 6 ×a3×k3+9.51×m×10 5 ×a1×k1+1.075×m×10 6 ×a2×k2+7.3355×10 5 ×m×(1-w-a1-a2-a3)+2.515×10 5 ×m×a1×k1+1.897×10 5 ×m×a2×k2}×(T1-T0)-6.7117×10 8 ×m×a1×k1-6.1654×10 8 ×m×a2×k2-1.5384×10 9 ×m×a3×k3; Among them, d1 is the inner diameter of the reactor, d2 is the wall thickness of the reactor, d3 is the thickness of the thermal insulation rock wool in the reactor, L is the length of the reactor, m is the total mass of the building material body in the reactor, n is the volume percentage of carbon dioxide in the flue gas, ρ is the density of the building material product, V is the volume of the reactor, w is the moisture content of the building material body, T1 is the temperature of the hydrothermal reaction during hydrothermal treatment, T0 is the initial temperature of the reactor, a1, a2, a3 are the mass percentages of dicalcium silicate, tricalcium silicate and calcium hydroxide in the building material body, respectively, k1, k2, k3 are the reaction constants of dicalcium silicate, tricalcium silicate and calcium hydroxide, respectively.

3. The method for preparing solid waste recycled materials with low energy consumption under the composite curing system according to claim 2, characterized in that: The temperature T1 of the hydrothermal reaction is 160-180°C.

4. The method for preparing solid waste recycled materials with low energy consumption under the composite curing system according to claim 1, characterized in that: In step S2, the mass ratio of calcium to silicon in the building material blank after mineralization treatment is 0.2-0.9:

1.

5. The method for preparing solid waste recycled materials with low energy consumption under the composite curing system according to claim 1, characterized in that: In step S2, the mass ratio of calcium to silicon in the building material blank after mineralization treatment is 0.3-0.7:

1.

6. The method for preparing solid waste recycled materials with low energy consumption under the composite curing system according to claim 1, characterized in that: In step S1, preparing solid waste into building material blanks includes the following steps: Mixing solid waste raw materials, adding water and stirring into a mixed slurry; The mixed slurry is subjected to preforming treatment to obtain a preformed body; Forming and pressing the preformed body to obtain a building material body; Among them, the solid waste raw materials include calcareous solid waste and siliceous aluminum solid waste, and the mass ratio of the calcareous solid waste to the siliceous aluminum solid waste is 5-45:15-65; the preforming treatment can adopt one of the slurry method, copying method, casting method and pressing method.

7. The method for preparing solid waste recycled materials with low energy consumption under the composite curing system according to claim 6, characterized in that: The calcareous solid waste includes at least one of steel slag, carbide slag, sludge or waste incineration fly ash, thiourea slag, slag, waste cement, red mud, magnesium slag, phosphate slag, lithium slag and the sintering product of calcium-containing solid waste; the siliceous and aluminous solid waste includes at least one of fly ash, glass tailings, large slag ash, slag, red mud, construction waste, sludge or waste incineration bottom ash, quartz sand and silicon-containing sludge.

8. The method for preparing solid waste recycled materials with low energy consumption under a composite curing system according to claim 6, characterized in that: The solid waste raw materials also include additional materials, and the mass ratio of the calcareous solid waste, the siliceous and aluminumous solid waste and the additional materials is 5-45:15-65:5-15.

9. The method for preparing solid waste recycled materials with low energy consumption under the composite curing system according to claim 8, characterized in that: The additional material includes at least one of fiber, wollastonite, bentonite, vermiculite, diatomaceous earth and aggregate.

10. The method for preparing solid waste recycled materials with low energy consumption under the composite curing system according to claim 9, characterized in that: The aggregate includes at least one of recycled aggregate and natural aggregate; the fiber includes at least one of plant fiber, mineral fiber, synthetic fiber, inorganic fiber and recycled fiber; wherein the plant fiber includes at least one of coniferous wood fiber, hardwood fiber, cotton and linen fiber, and fruit fiber; the mineral fiber includes asbestos fiber; the synthetic fiber includes at least one of nylon fiber, nylon fiber, polyester fiber, acrylic fiber, vinylon fiber, polypropylene fiber, and PVA fiber; the inorganic fiber includes at least one of glass fiber and metal fiber; the recycled fiber includes at least one of waste paper fiber, recycled mask fiber, and viscose fiber.

11. The method for preparing solid waste recycled materials with low energy consumption under a composite curing system according to claim 6, characterized in that: The water content of the mixed slurry is 65-85%, the water content of the preformed body is 40-55%, and the water content of the building material body after compression molding is 25-45%.

12. The method for preparing solid waste recycled materials with low energy consumption under a composite curing system according to claim 1, characterized in that: The volume proportion of carbon dioxide in the flue gas is 8-99%.

13. The method for preparing solid waste recycled materials with low energy consumption under a composite curing system according to claim 1, characterized in that: In step S2, during the mineralization treatment, the mineralization pressure in the reactor is 0.1-2 MPa.

14. The method for preparing solid waste recycled materials with low energy consumption under a composite curing system according to claim 1, characterized in that: In step S3, the hydrothermal treatment includes introducing water vapor into the reactor to continuously raise the temperature in the reactor to a hydrothermal reaction temperature T1, and then performing hydrothermal curing, and the curing time is controlled within 1 to 24 hours.

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