Method for granulating by utilizing industrial solid waste low-temperature curing muck

Abstract

The invention discloses a method for granulating by utilizing industrial solid waste low-temperature curing muck, and belongs to the technical field of building materials. The industrial solid waste is prepared from the following components in parts by weight: 60 to 80 parts of steel slag powder, 10 to 20 parts of byproduct gypsum, 5 to 20 parts of slag powder, 5 to 20 parts of limestone powder and 5 to 10 parts of exciting agent, and the mass ratio of the industrial solid waste to the construction waste muck is (10 to 30): 100. According to the invention, the steel slag powder provides an alkaline reaction environment and supplements a calcium source, the desulfurized gypsum powder provides SO4 < 2->, the slag powder provides an active calcium source, the superfine limestone powder provides hydration product nucleation sites and a physical filling effect, and under the action of the exciting agent and in an environment of 40-50 DEG C, industrial solid wastes are subjected to a synergetic hydration reaction to generate a compact gel product; the activity of potential silicon-aluminum minerals in the building residue soil is stimulated, formation of hydration hardening strength is further promoted, and low-temperature curing granulation of the industrial solid waste and the building residue soil is achieved.

Description

Technical Field

[0001] The invention relates to a method for preparing artificial granular materials by solidifying industrial solid waste and construction waste slag at low temperature, belonging to the technical field of building materials. Background Art

[0002] With the rapid development of modernization, the global attention to the development and utilization of underground space has been increasing, setting off a climax of underground engineering construction, and the output of engineering slag has increased day by day. After sand washing, sand-containing engineering slag will produce a large amount of construction waste slag or mud. There are many clay particles, high water content, and low reaction activity in the engineering slag, which belongs to the soil with poor engineering properties. Therefore, it is difficult to use it on a large scale in projects such as roadbed backfill. Its large-scale storage causes waste of land resources and serious environmental pollution. At present, by synergistically solidifying construction slag with multi-source solid waste and then granulating it, it can be made into an excellent roadbed filler, thereby realizing the large-scale utilization of construction slag. At present, high-quality cementitious materials (such as lime, cement or other highly active cementitious materials) are often used to solidify construction slag to prepare products with excellent performance, which has high carbon emissions and poor economy. Therefore, it is necessary to use industrial solid waste to replace traditional high-quality cementitious materials such as lime and cement to achieve waste treatment and low-carbon preparation and application of multi-solid waste cementitious materials based on construction slag. However, due to the low activity of construction waste, it is difficult to solidify at room temperature, resulting in poor early mechanical properties. If a higher temperature (such as above 80°C) is used, although its early mechanical properties can be greatly improved, it will also bring problems such as high energy consumption, high carbon emissions and high costs. In addition, the use of sintering, microwave sintering and other methods for granulation is more expensive and difficult to accept in actual projects.

[0003] For example, the Chinese invention patent with application number CN202110147079.0 proposes a microwave sintering method for slag ceramsite, the main steps of which are: (1) stirring slag slag, fly ash, ordinary silicate cement and water in a mass ratio of 40-60:80-120:2-5:5-10 for 2-10 minutes to obtain a mixture, and in this process, adding a low-density bauxite reinforcing agent calcined at 400-500°C for 5-10 hours, and the mass ratio of the bauxite to the cement is 1.5-3; (2) pelletizing on a balling plate, the balling time is 5-15 minutes, and after taking out, it is placed in a drying box for drying for 12-36 hours, and the product is added to a microwave reactor for microwave treatment for 5-15 minutes, the microwave power is 3000-5000W, and cooled to obtain slag ceramsite. This invention method uses microwave sintering, which has the disadvantages of high cost, high energy consumption and high carbon emissions, and is difficult to handle and utilize on a large scale.

[0004] To sum up, the shortcomings of the existing technology are: the cost of solidifying slag granulation with high-activity cementitious materials such as cement, fly ash, lime, slag powder, etc. is high; the cost, energy consumption and carbon emissions of granulation materials using high-temperature sintering, microwave sintering, high-temperature rotary kiln and other methods are high; some granulation technologies use less than 60% of slag, resulting in low utilization rate.

[0005] The present invention comprehensively considers the above problems, uses industrial solid waste and solidifies and granulates construction waste at low temperature (no more than 50°C), thereby breaking through the technical bottleneck of large-scale utilization of construction waste. Conventional construction waste refers to the waste from the foundation pit excavated before construction of a building project. Summary of the invention

[0006] The present invention provides a method for granulating construction waste soil solidified at low temperature by industrial solid waste, characterized in that the moisture content of construction waste soil (including mud) is regulated by airing or blending so as not to exceed the plastic limit moisture content of the soil material, and then 10%-30% of the mass of the soil material (dry basis) of solid waste-based solidifying materials is added, and after being fully mixed, the materials are stewed for 12-24 hours, and granulation is carried out in two ways (one of the two is selected): (1) using a ball-forming disk or extrusion cutting granulation process to prepare particles with a particle size of 1 mm-20 mm, and placing them in a low temperature environment of 40-50°C for curing for 3d-7d; (2) placing the mixture into a mold for extrusion molding (without size) to form a block, placing the block in a low temperature environment of 40-50°C for curing for 3d-7d, and then crushing and screening the block to form sand-like particles with a particle size of 1 mm-20 mm.

[0007] Specific operation and material requirements are as follows:

[0008] The industrial solid waste comprises steel slag powder, by-product gypsum, slag powder, limestone powder and activator, and the composition ratio is: 60-80 parts by weight of steel slag powder, 10-20 parts by weight of by-product gypsum, 5-20 parts by weight of slag powder, 5-20 parts by weight of limestone powder and 5-10 parts by weight of activator.

[0009] The steel slag powder is converter steel slag or electric furnace steel slag, and the specific surface area of ​​the ground powder is not less than 450m 2 / kg, the by-product gypsum includes one or more of desulfurized gypsum, phosphogypsum, fluorinated gypsum, and titanium gypsum, the slag powder is S95 grade, the limestone powder has a sum of the mass fractions of calcium carbonate and magnesium carbonate of not less than 90%, and the specific surface area of ​​the ground powder is not less than 400m 2 / kg.

[0010] The activator is a mixture of calcium hydroxide, sodium sulfate, calcium oxalate and diethanol monoisopropanolamine; the functions of the activator are as follows: calcium hydroxide provides an external calcium source and alkaline components in the system, and sodium sulfate provides SO4 required to promote early strength and promote crystal nucleation.2- Calcium oxalate and diethanol monoisopropanolamine are used as early strength agents to promote hydration and improve early strength; the activator is composed of 10-20 parts by weight of calcium hydroxide, 5-10 parts by weight of sodium sulfate, 1-3 parts by weight of calcium oxalate, and 0.5-1 parts by weight of diethanol monoisopropanolamine.

[0011] The stewing process is to cover the slag mixed with solid waste materials with plastic cloth or put it in a sealed container in an environment with a temperature of 15-30°C to keep it from losing water and treat it for 12-24 hours;

[0012] The low temperature environment of 40-50°C is a closed space with a temperature of 40-50°C and a humidity of not less than 90% established by using waste heat from certain industrial production departments, or a closed space with a temperature of 40-50°C and a humidity of not less than 90% established by using solar greenhouses and thermal insulation technical measures.

[0013] According to the present invention, low-cost granulation of industrial solid waste and construction debris can be achieved. The product can completely or partially replace gravel, pebbles or crushed stones and be used as roadbed and foundation materials. It can also be used as granular filling material for drainage layers and blind ditch laying in landfills, and can also be used as aggregate for fluidized solidified soil.

[0014] The technical effects of the present invention are as follows:

[0015] The present invention uses a small amount of industrial solid waste (including steel slag powder that provides an alkaline reaction environment and supplements calcium sources, and SO4 2- The desulfurized gypsum powder, slag powder providing active calcium source, limestone powder providing nucleation sites for hydration products and physical filling effect and construction slag rich in potential low-activity silico-alumina minerals are used as raw materials. Under the action of a small amount of activator, solar energy or industrial waste heat is used to form a low-temperature environment of 40℃-50℃, so as to realize the low-temperature solidification and granulation of industrial solid waste and construction slag. Its 3-day strength can reach 2-5MPa, which can replace gravel, pebbles or crushed stones for roadbed, foundation, mine filling and other projects, solving the problem of large-scale application of slag; this kind of slag-based artificial granular material contains 80%-90% of construction waste slag, realizing the high added value utilization of construction waste slag and multi-source industrial solid waste, solving the problem of large stockpiles of large-scale industrial solid wastes such as construction waste slag, steel slag and desulfurized gypsum; using solar energy or industrial waste heat to achieve a low-temperature solidification environment of 40℃-50℃, realizing the low cost and low energy consumption of slag-based artificial granular materials, which can generate huge economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Flowchart of the invention method

[0017] Figure 2 Schematic diagram of soil-based artificial granular material curing box DETAILED DESCRIPTION

[0018] The technical solution of the present invention is described in detail below through specific embodiments.

[0019] Example 1

[0020] A method for granulating industrial solid waste by low-temperature solidification of slag, comprising the following steps:

[0021] Step 1): Dry the construction waste soil (including mud) with a natural moisture content of 45% (plastic limit moisture content = 28%) in the sun until the moisture content is 21%; grind the converter slag powder with a ball mill until its specific surface area is 460m 2 / kg; the by-product gypsum is desulfurized gypsum with a particle size of 250 mesh; the slag powder is S95 grade with a particle size of 250 mesh; the mass fraction of calcium carbonate in the limestone powder is measured to be 90%, the mass fraction of magnesium carbonate is measured to be 2%, and the specific surface area of ​​the ground limestone powder is 420m 2 / kg.

[0022] Step 2): the mass fraction is: construction waste slag = 80%, solid waste-based solidification material = 20%, wherein the weight proportions of each solid waste-based solidification material are converter slag powder: desulfurization gypsum powder: slag powder: limestone powder: activator = 60:10:10:15:5, and the weight proportions of each activator are calcium hydroxide: sodium sulfate: calcium oxalate: diethanol monoisopropanolamine = 10:5:1:0.5; in an environment with a temperature of 30°C, the slag mixed with the solidification material is covered with plastic cloth or placed in a sealed container to keep it from losing water, and the material is simmered for 12 hours.

[0023] Step 3): Use a ball-forming disc or extrusion cutting method to prepare particles with a particle size of 1 mm to 20 mm and place them in Figure 2 The material is cured for 3 days in an artificial aggregate curing box in a low-temperature environment with a temperature of 40 and a humidity of 90%.

[0024] Step 4): The low-temperature cured raw material is rounded, burrs are removed, and broken materials are screened to obtain sample materials, which are prepared into finished products of artificial aggregates of construction waste slag with different particle sizes and shapes. The finished products are tested according to the light aggregate and its test method GB / T17431.1-1998 standard, and the results meet the standards, as shown in Table 1.

[0025] Example 2

[0026] A method for granulating industrial solid waste by low-temperature solidification of slag, comprising the following steps:

[0027] Step 1): drying construction waste soil (including mud) with a natural moisture content of 45% (plastic limit moisture content = 28%) in the sun until the moisture content is 21%; grinding electric furnace slag powder with a ball mill to a specific surface area of ​​460m2 / kg; using phosphogypsum as the by-product gypsum with a particle size of 250 mesh; slag powder of S95 grade with a particle size of 250 mesh; the mass fraction of calcium carbonate in the limestone powder used is measured to be 90%, the mass fraction of magnesium carbonate is measured to be 2%, and the specific surface area of ​​the ground limestone powder is 420m2 / kg. 2 / kg.

[0028] Step 2): the mass fraction is: construction waste slag = 90%, solid waste-based solidification material = 10%, wherein the weight proportions of each solid waste-based solidification material are electric furnace slag powder: desulfurization gypsum powder: slag powder: limestone powder: activator = 70:5:7:8:10, and the weight proportions of each activator are calcium hydroxide: sodium sulfate: calcium oxalate: diethanol monoisopropanolamine = 15:10:2:1; in an environment with a temperature of 30°C, the slag mixed with the solidification material is covered with plastic cloth or placed in a sealed container to keep it from losing water, and the material is simmered for 24 hours.

[0029] Step 3): The processed material is extruded through a die (the die size is not limited) to form a block, and then placed in Figure 2 The block is cured in an artificial aggregate curing box in a low-temperature environment with a temperature of 40° C. and a humidity of 90% for 3 days, and then the block is crushed and sieved to form sand-like particles with a particle size of 1 mm to 20 mm.

[0030] Step 4): The crushed and screened raw materials are rounded, burrs are removed, and broken materials are screened to obtain sample materials, which are prepared into finished products of artificial aggregates of construction waste slag with different particle sizes and shapes. The finished products are tested according to the light aggregate and its test method GB / T17431.1-1998 standard, and the results meet the standards, as shown in Table 1.

[0031] Table 1 Example test data

[0032] Bulk density 3d cylinder compressive strength Water absorption Example 1 <![CDATA[378.1Kg / m 3 ]]> 2.5MPa 7％ Example 2 <![CDATA[379.6Kg / m 3 ]]> 3.0MPa 6％

Claims

1. A method for granulating industrial solid waste by low-temperature solidification of slag, characterized in that The following steps are involved: S1 regulates the moisture content of construction waste soil; S2 weighs a certain amount of industrial solid waste; S3 evenly mixes industrial solid waste and construction waste slag and soil materials, and stews the mixture to make it uniform; S4 directly granulates the pellets and then puts them into a low temperature environment for curing or forms blocks for low temperature curing before crushing, screening and granulation; In step S1, the moisture content of the construction waste soil is regulated by drying or blending so that the moisture content of the soil does not exceed the plastic limit moisture content of the soil; In step S2, industrial solid waste is weighed in a dry basis mass ratio of (10-30):100 to construction waste slag; the industrial solid waste is composed of steel slag powder, by-product gypsum, slag powder, limestone powder and an activator, and the composition ratio is: 60-80 parts by weight of steel slag powder, 10-20 parts by weight of by-product gypsum, 5-20 parts by weight of slag powder, 5-20 parts by weight of limestone powder, and 5-10 parts by weight of the activator; In step S2, the steel slag powder is converter steel slag or electric furnace steel slag, and the specific surface area of ​​the ground powder is not less than 450m 2 / kg; the by-product gypsum includes one or more of desulfurized gypsum, phosphogypsum, fluorinated gypsum, and titanium gypsum; the activator is a mixture of calcium hydroxide, sodium sulfate, calcium oxalate, and diethanol monoisopropanolamine; the activator is composed of 10-20 parts by weight of calcium hydroxide, 5-10 parts by weight of sodium sulfate, 1-3 parts by weight of calcium oxalate, and 0.5-1 parts by weight of diethanol monoisopropanolamine. In step S3, the process of treating the mixture of industrial solid waste and construction waste and slag soil by stewing is to cover the construction waste and slag mixed with solid waste materials with plastic sheeting or put them into a sealed container in an environment with a temperature of 15-30°C to keep them from losing water, and treat them for 12-24 hours; In step S4, the pellets obtained by direct granulation are placed in a low-temperature environment for curing. Direct granulation refers to the use of a ball-forming disk or extrusion cutting granulation process to prepare particles with a particle size of 1mm-20mm; the low-temperature environment is a closed space with a temperature of 40-50°C and a humidity of not less than 90% established by using waste heat from certain industrial production departments, or a closed space with a temperature of 40-50°C and a humidity of not less than 90% established by using solar greenhouses and insulation technical measures; the pellets are placed in the low-temperature environment for curing, and the curing time is 3d-7d.

2. The method according to claim 1, characterized in that: The slag powder is of grade S95; the specific surface area of ​​the ground powder is not less than 400m 2 / kg.

3. The method according to claim 1, characterized in that: The sum of the mass fractions of calcium carbonate and magnesium carbonate in the limestone powder is not less than 90%.

4. The method according to claim 1, characterized in that: In step S4, the formed blocks are subjected to low-temperature curing and then crushed, screened and granulated, which means that the mixture is put into a mold for extrusion molding to form a block, the block is cured in a closed space at 40-50°C and a humidity of not less than 90% for 3d-7d, and then the block is crushed and screened to form sand-like particles with a particle size of 1mm-20mm.

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