Preparation method of high-strength lightweight artificial aggregate

Abstract

The invention relates to a preparation method of a high-strength lightweight artificial aggregate, which comprises the following steps: A, preparing an artificial aggregate raw material: respectively grinding four solid waste materials and additives by using a grinding machine to prepare the artificial aggregate raw material; b, balling: adding water accounting for 26% of the weight of the powder into the powder obtained in the step A, uniformly stirring, and then putting the uniformly stirred powder into a granulator for granulation; c, performing high-temperature and high-pressure steam curing, namely putting the spherical blank body prepared in the step B into a still kettle, and performing steam pressing for 4 hours; and D, carbonizing: introducing tail gas of a simulated steel mill into the aggregate in the step C, and carbonizing for 12 hours to obtain a final finished product. By introducing the additive sodium sulfate and quicklime and adopting high-temperature and high-pressure steam curing and carbonization processes, the strength of the artificial aggregate is greatly improved, and meanwhile, the potential expansion hazard of the steel slag is eliminated; a large number of solid wastes difficult to treat can be treated, the physical and mechanical properties of the concrete are improved, and finally, the high-strength lightweight artificial aggregate capable of replacing natural aggregate is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of artificial aggregate preparation, in particular to a method for preparing high-strength and lightweight artificial aggregate. Background Art

[0002] Nowadays, due to strict environmental protection requirements and the shortage of qualified natural sand and gravel, major commercial mixing stations use a large amount of machine-made sand. However, there are some problems with the use of machine-made sand. First, the fineness modulus, particle grading, stone powder content, apparent density, porosity, crushing value, and methylene blue MB value of machine-made sand are not as good as natural river sand; secondly, the raw materials for machine-made sand and gravel are usually granite, basalt, river pebbles, pebbles, andesite, rhyolite, diabase, diorite, sandstone, limestone, etc. The machine-made sand produced by them is distinguished by the type of rock, and there are also differences in strength. Due to the poor performance of the machine-made sand used in commercial mixing stations, the concrete has high viscosity, poor rheology, poor cracking resistance, and poor density. Therefore, it is necessary to prepare a fine aggregate.

[0003] As we all know, steel slag has a high density due to its iron content. The density of raw steel slag is 3.2-3.8, while the density of natural stones such as boulders and pebbles is 2.6, which is a big difference in density. In addition, the steel industry has a large carbon emission, and carbon reduction is an urgent need.

[0004] Coal is used for heating and power generation, and the stockpiles of fly ash and desulfurization gypsum are extremely large, but their resource utilization is limited. They occupy a large amount of land for storage and cause environmental pollution.

[0005] The general disposal methods for discarded plastics are landfill and incineration. These two disposal methods either occupy a large area or consume a lot of energy, and the cost is very high. There is an urgent need for a safe, large-scale and low-cost disposal method.

[0006] In order to dispose of solid waste materials such as steel slag, waste plastics, fly ash, desulfurized gypsum, etc. in large quantities and reduce the disposal cost, it is necessary to prepare a low-cost, sintering-free, lightweight and high-strength artificial fine aggregate that can dispose of a variety of solid waste materials in large quantities to replace machine-made sand. Summary of the invention

[0007] The technical problem to be solved by the present invention is: in order to overcome the deficiencies in the prior art, a method for preparing a high-strength and lightweight artificial aggregate is provided.

[0008] The technical solution adopted by the present invention is: a method for preparing high-strength and lightweight artificial aggregate, comprising the following steps:

[0009] A. Preparation of artificial aggregate raw materials: grinding four solid waste materials and additives with a mill to a specific surface area of ​​not less than 550m2 / g to prepare powder of artificial aggregate raw materials, wherein the weight component ratio of each solid waste material in the powder is: fly ash 14%, steel slag 60-66%, desulfurized gypsum 10%, waste plastic 8-14%; the weight component ratio of the additives is: quicklime 1.5%, sodium sulfate 0.5%;

[0010] B. forming into balls, putting the powder obtained in step A into a container, adding water accounting for 26% of the weight of the powder and stirring evenly, then putting the stirred powder into a granulator for granulation, and controlling the granulation process so that the particle size of the spherical embryo after balling is less than 5.0 mm;

[0011] C. High temperature and high pressure steam curing: the spherical embryos prepared in step B are placed in an autoclave and autoclaved at a temperature of 180° C. and a pressure of 1 MPa for 4 hours to obtain aggregates;

[0012] D. Carbonization: The aggregates in step C are placed in a carbonization kettle, and simulated steel plant tail gas is introduced, wherein the carbon dioxide concentration is 22%, the temperature is 80 degrees, and the final product is obtained after carbonization for 12 hours.

[0013] Among them, fly ash is the waste generated by power generation in power plants, and waste plastics are classified domestic waste.

[0014] Furthermore, the steel slag described in the present invention is obtained by treating the waste steel slag produced by steelmaking in a steel plant through a heat-stifling process.

[0015] Furthermore, the desulfurized gypsum described in the present invention has a moisture content of 18% and a chloride ion content of 300 ppm.

[0016] Furthermore, the density of the waste plastics of the present invention is 0.88 g / cm3, and it can resist corrosion by acid, alkali, salt solution and various organic solvents at a temperature below 80°C, and soften when heated to 130-170°C. After being heated to 180°C and in a fluid state, it penetrates into the pores, cracks and capillaries of the aggregate. The fluid state at 180°C will produce a bonding effect. As an organic material, its surface tension is much lower than that of water, and it is very easy to penetrate into the pores, cracks and capillaries of the aggregate, plug the pores, repair the cracks, and make the aggregate dense, crack-proof, waterproof and highly durable.

[0017] At the same time, because waste plastics have high strength, toughness and ductility, they can enhance the strength, toughness and elongation of aggregates. In addition, because waste plastics are very light, adding them can achieve light weight and high strength.

[0018] Desulfurized gypsum can stimulate the activity of fly ash and steel slag and increase the strength of artificial aggregate;

[0019] Quicklime and sodium sulfate not only stimulate the activity of fly ash and steel slag, but also increase the absorption of carbon dioxide, which can further increase the strength, achieve low carbon and high strength, and improve the stability of artificial aggregates.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. The raw materials used in the present invention are all solid waste materials that are difficult to process, and a large number of solid waste materials can be processed. Because there is no sintering, it is more low-carbon and environmentally friendly, and finally forms a low-cost, sintering-free, high-strength and lightweight artificial aggregate that replaces natural aggregates;

[0022] 2. The use of quicklime and sodium sulfate in combination with high temperature and high pressure steam curing and carbonization process can enhance the strength of artificial aggregates while significantly increasing the absorption of carbon dioxide, further improving the strength of artificial aggregates while eliminating the potential expansion hazards of steel slag and reducing water absorption;

[0023] 3. By introducing waste plastics, which have the characteristics of light weight, high strength, corrosion resistance and hydrophobicity, they can also significantly enhance the strength and toughness of artificial aggregates at 180°C and reduce water absorption, making their water absorption rate much lower than that of existing artificial aggregates. DETAILED DESCRIPTION

[0024] The embodiments of the present invention are described in detail below. The embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0025] Embodiment 1, a method for preparing high-strength lightweight artificial aggregate, comprising the following steps:

[0026] A. Preparation of artificial aggregate raw materials: grinding four solid waste materials and additives respectively with a mill to a specific surface area of ​​not less than 550m2 / g to prepare powder of artificial aggregate raw materials, wherein the weight component ratio of each solid waste material in the powder is: fly ash 14%, steel slag 66%, desulfurized gypsum 10%, and waste plastic 8%; the weight component ratio of the additives is: quicklime 1.5%, sodium sulfate 0.5%;

[0027] B. forming into balls, putting the powder obtained in step A into a container, adding water accounting for 26% of the weight of the powder and stirring evenly, then putting the stirred powder into a granulator for granulation, and controlling the granulation process so that the particle size of the spherical embryo after balling is less than 5.0 mm;

[0028] C. High temperature and high pressure steam curing: the spherical embryos prepared in step B are placed in an autoclave and autoclaved at a temperature of 180° C. and a pressure of 1 MPa for 4 hours to obtain aggregates;

[0029] D. Carbonization: The aggregates in step C are placed in a carbonization kettle, and simulated steel plant tail gas is introduced, wherein the carbon dioxide concentration is 22%, the temperature is 80 degrees, and the final product is obtained after carbonization for 12 hours.

[0030] Among them, fly ash is the waste generated by power generation in power plants, and waste plastics are classified domestic waste. Steel slag is the waste steel slag produced by steelmaking in steel plants that is obtained through a hot stuffing process; the moisture content of desulfurized gypsum is 18%, and the chloride ion content is 300ppm.

[0031] The density of waste plastic is 0.88g / cm3. It can resist corrosion from acid, alkali, salt solution and various organic solvents below 80℃. It softens when heated to 130-170℃ and becomes fluid when heated to 180℃, penetrating into the pores, cracks and capillaries of aggregate to produce a bonding effect.

[0032] In Example 2, the weight proportions of the various substances in the powder of the artificial aggregate raw material are set to: fly ash 14.0%, steel slag 64.0%, desulfurized gypsum 10%, waste plastic 10.0%, quicklime 1.5%, sodium sulfate 0.5%, and the preparation method remains the same as in Example 1 to obtain the final product.

[0033] In Example 3, the weight proportions of the various substances in the powder of the artificial aggregate raw material are set to: fly ash 14.0%, steel slag 62.0%, desulfurized gypsum 10%, waste plastic 12.0%, quicklime 1.5%, sodium sulfate 0.5%, and the preparation method remains the same as in Example 1 to obtain the final product.

[0034] In Example 4, the weight proportions of the various substances in the powder of the artificial aggregate raw material are set to: fly ash 14.0%, steel slag 60.0%, desulfurized gypsum 10%, waste plastic 14.0%, quicklime 1.5%, sodium sulfate 0.5%, and the preparation method remains the same as in Example 1 to obtain the final product.

[0035] For comparison, the high-temperature autoclaved artificial aggregate with a diameter of less than 5 mm currently sold in the market has a density of 1.88 g / cm3, a cylinder pressure strength of 18.6 Mpa, a water absorption rate of 10.5%, and a softening coefficient of 0.88;

[0036] The properties of the high-strength lightweight artificial aggregates prepared in Examples 1, 2, 3 and 4 of the present invention and the comparative examples are shown in the following table:

[0037]

[0038] As can be seen from the above table, it is obvious that the carbon dioxide absorption of Examples 1-4 is much higher than that of the comparative example, up to 12.0%, and the density is much lower than that of the comparative example, up to 18.6%. The higher the carbon dioxide absorption, the lower the carbon content of the aggregate. In addition, the key mechanical properties of cylinder compressive strength, water absorption rate, and softening coefficient are far better than those of the comparative example.

[0039] The high-strength and lightweight artificial aggregate prepared by Example 4 of the present invention has the following physical and mechanical properties: the particles are continuously graded, the final density can be as low as 1.53 g / cm3, the cylinder pressure strength is as high as 32 MPa, the water absorption rate is as low as 1.6%, the softening coefficient is as high as 1.0, and it is spherical and continuously graded. It has strong physical water reduction and strength and density increase effects, and is a high-quality artificial sand that can replace machine-made sand.

[0040] At present, the disposal fee of waste plastics is extremely high. Adding waste plastics to artificial aggregates can not only achieve the purpose of low-cost harmless disposal, but also offset the cost of artificial aggregate preparation, enhance the economy and physical and mechanical properties of artificial aggregates, killing two birds with one stone.

[0041] It can be seen from the above data that the artificial aggregate prepared by the present invention has a large carbon dioxide absorption capacity, can dispose of a large amount of difficult-to-treat solid waste, is low-carbon and environmentally friendly, has good physical and mechanical properties, and has extremely obvious economic and social benefits.

Claims

1. A method for preparing high-strength and lightweight artificial aggregate, characterized in that: The following steps are involved: A. Preparation of artificial aggregate raw materials: grinding four solid waste materials and additives with a mill to a specific surface area of ​​not less than 550m2 / g to prepare powder of artificial aggregate raw materials, wherein the weight component ratio of each solid waste material in the powder is: fly ash 14%, steel slag 60-66%, desulfurized gypsum 10%, waste plastic 8-14%; the weight component ratio of the additives is: quicklime 1.5%, sodium sulfate 0.5%; B. forming into balls, putting the powder obtained in step A into a container, adding water accounting for 26% of the weight of the powder and stirring evenly, then putting the stirred powder into a granulator for granulation, and controlling the granulation process so that the particle size of the spherical embryo after balling is less than 5.0 mm; C. High temperature and high pressure steam curing: the spherical embryos prepared in step B are placed in an autoclave and autoclaved at a temperature of 180° C. and a pressure of 1 MPa for 4 hours to obtain aggregates; D. Carbonization: The aggregates in step C are placed in a carbonization kettle, and simulated steel plant tail gas is introduced, wherein the carbon dioxide concentration is 22%, the temperature is 80 degrees, and the final product is obtained after carbonization for 12 hours.

2. The method for preparing a high-strength and lightweight artificial aggregate according to claim 1, characterized in that: The steel slag is obtained by treating the waste steel slag produced by steelmaking in a steel plant through a heat-stifling process.

3. The method for preparing a high-strength and lightweight artificial aggregate according to claim 1, characterized in that: The desulfurized gypsum has a moisture content of 18% and a chloride ion content of 300 ppm.

4. The method for preparing a high-strength and lightweight artificial aggregate according to claim 1, characterized in that: The waste plastic has a density of 0.88 g / cm3. After being heated to 180°C and becoming fluid, it penetrates into the pores, cracks and capillaries of the aggregate to produce a bonding effect.

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