A fluidized solidified soil based on water treatment plant tailings and its preparation method

Abstract

This invention relates to the field of solid waste utilization technology, and in particular to a fluidized solidified soil based on water treatment plant tailings and its preparation method. The components, by mass, include 10-80 parts of water treatment plant tailings, 50-100 parts of slag, and 16-28 parts of solidification material. This invention, employing the aforementioned fluidized solidified soil based on water treatment plant tailings and its preparation method, provides a mix design and calculation method based on the compounding of high-density soil materials from water treatment plant tailings and slag. This method not only solves the problems of high viscosity, lack of fluidity, and water seepage and shrinkage of high-density soil materials in the preparation of fluidized solidified soil from water treatment plant tailings, but also improves the quality of the fluidized solidified soil, thereby increasing the source reduction and resource utilization rate of construction waste.

Description

Technical Field

[0001] This invention relates to the field of solid waste utilization technology, and in particular to a fluidized solidified soil based on tailings from a water treatment plant and its preparation method. Background Technology

[0002] With the increasing "siphon effect" of large and medium-sized cities, rapid population growth in central cities, and accelerated construction of urban lifeline projects, the demand for drinking water is constantly increasing, leading to a growing number of water purification plants. Conventional aluminum salts are coagulants used in water purification, and due to their effectiveness and low cost, they have become the most commonly used flocculant in the water treatment industry worldwide. However, water purification generates a large amount of byproducts—water treatment plant tailings sludge. This sludge is composed of high levels of Al2O3 and SiO2, similar to conventional clay.

[0003] Currently, the main methods for disposing of water treatment plant tailings are landfilling, incineration, and sedimentation in sedimentation tanks. Some research also explores their application in the production of ceramic bricks and cement clinker. Traditional methods of tailings disposal are costly, exceeding 300 yuan per cubic meter. Furthermore, increasing the amount of tailings reduces the flexural strength of ceramic bricks, and the presence of organic matter hinders cement hydration and hardening, thus reducing compressive strength. Therefore, to a certain extent, the resource utilization rate of water treatment plant tailings is relatively low, disposal costs are high, and available disposal sites are limited, resulting in a waste of soil resources and failing to fundamentally eliminate the adverse environmental impacts.

[0004] Furthermore, with the continuous development of urban infrastructure construction in my country, earthwork backfilling has become a crucial part of the construction of foundations and various underground facilities. The scope of backfilling is extensive, including foundation pit backfilling, trench backfilling, pipeline backfilling, roadbed backfilling, and so on. In the past, backfilling in engineering construction required the consumption of large quantities of natural graded sand and gravel aggregates. Graded sand and gravel are non-renewable resources, and if used without restraint, they will eventually be depleted. Traditional backfill materials are ineffective at the junction of the pipe's horizontal diameter and the foundation, as the narrow gap makes it difficult for both manual labor and equipment to fully utilize their advantages, making it difficult to guarantee backfill quality. Poor backfill quality at the junction can lead to pipe detachment, causing deformation and ultimately reducing the pipe's service life. Modern pipeline projects are increasingly complex, and new and old pipelines inevitably intersect. When laying new pipelines around old pipelines, the surrounding backfill soil is always disturbed, and the issue of secondary excavation for backfilling must also be considered.

[0005] Currently, there is limited research on solidification and improvement of tailings from water treatment plants, which are characterized by small particle size, high moisture content, and high organic matter content. In particular, there is a lack of research on mix design and calculation methods for preparing fluidized solidified soil based on the resource utilization of tailings from water treatment plants. If solidification and improvement are carried out by simply adding cement, it is easy to hinder cement hydration, prolong the setting time, and at the same time, the strength is low and the resistance to wet-dry cycles is poor. If only density-adjusted soil materials such as sandy soil, gravelly sand, cobble gravel soil, and moderately weathered rock soil are used to prepare fluidized solidified soil, in order to make it highly fluid, there will be a lot of free water in the slurry, resulting in a high bleeding rate. At the same time, the heavy components sink, causing uneven shrinkage and surface cracking. Summary of the Invention

[0006] The purpose of this invention is to provide a fluidized solidified soil based on water treatment plant tailings and its preparation method. It provides a mix design and calculation method based on the compounding of high-density soil material in water treatment plant tailings and slag soil. This can solve the problems of high viscosity, lack of fluidity and water bleeding and shrinkage of high-density soil material in the preparation of fluidized solidified soil based on water treatment plant tailings, and improve the quality of fluidized solidified soil, thereby increasing the source reduction and resource utilization rate of construction waste.

[0007] To achieve the above objectives, the present invention provides a fluidized solidified soil based on water treatment plant tailings, wherein the components include 10-80 parts by mass of water treatment plant tailings, 50-100 parts of slag and soil, and 16-28 parts by mass of solidification material.

[0008] Preferably, the components of the curing material, by mass percentage, are: cement 15-32%, mineral powder 31-32%, fly ash 22-38%, calcium hydroxide 4-5%, calcium sulfate 7-12%, surfactant 1-2%, and water-reducing agent 1-2%.

[0009] Preferably, the components include 40-65 parts by mass of water treatment plant tailings, 65-80 parts of slag, and 20-25 parts of solidification material.

[0010] Preferably, the components of the curing material, by mass percentage, are: cement 21-26%, mineral powder 31-32%, fly ash 26-32%, calcium hydroxide 4-5%, calcium sulfate 8-11%, surfactant 1%, and water-reducing agent 1%.

[0011] The above-mentioned method for preparing fluidized solidified soil based on water treatment plant tailings includes the following steps:

[0012] S1. Draw a graph of mud wet density - flow value - 28d compressive strength with mud wet density as the horizontal axis and flow value and 28d compressive strength as the vertical axes.

[0013] S2. Based on the flow value and 28-day compressive strength in the construction requirements, select the first overlapping shaded area in the mud wet density-flow value-28-day compressive strength graph obtained in S1, and select the maximum value of the mud wet density in the first overlapping shaded area.

[0014] S3. Draw a graph of cured material-flow value-compressive strength with the mass of cured material as the horizontal axis and the flow value and 28d compressive strength as the vertical axes.

[0015] S4. Based on the flow value and 28-day compressive strength in the construction requirements, select the second overlapping shaded area in the cured material-flow value-compressive strength graph obtained in S3, and select the minimum value of the cured material mass in the second overlapping shaded area.

[0016] S5. Measure the initial moisture content in the tailings of the water treatment plant and the initial moisture content in the slag, respectively. Calculate the mass of tailings, slag, theoretical water consumption, and additional water consumption required per cubic meter of fluidized solidified soil at the wet density of the mud obtained in S2.

[0017] S6. Based on the mass of the tailings sludge from the water treatment plant calculated in S5 and the amount of additional water required, put both into a ball mill to dissolve the sludge. After dissolving the sludge, put it into a storage tank and continue stirring.

[0018] S7. Add the slag to the slurry storage tank in S6 according to the slag mass calculated in S5, and measure the wet density of the slurry after continuous stirring.

[0019] S8. Calculate the error value based on the measured value of mud wet density obtained in S7 and the maximum value of mud wet density in S2. Based on the error value, select whether to add slag or water to obtain the final mixed mud.

[0020] S9. Extract the mixed mud from S8, add the solidification material and stir until uniform to obtain fluidized solidified soil.

[0021] Preferably, in S5, the theoretical water consumption is calculated as follows:

[0022]

[0023] Among them, M w G represents the theoretical water consumption. s M represents the specific gravity of soil particles after the mixture of tailings and slag from a water treatment plant. c G represents the amount of curing material added. c ρ is the specific gravity of the cured material. t This refers to the wet density of the mud.

[0024] Preferably, in S5, the total mass of tailings and slag from the water treatment plant is calculated as follows:

[0025] M s=ρ t ×1000-M w -M c ;

[0026] Among them, M s The total mass of tailings and slag from the water treatment plant;

[0027] Quality M of tailings sludge from water treatment plant s1 The calculation is shown below.

[0028]

[0029] The quality M of the slag s2 The calculation is shown below.

[0030]

[0031] Wherein, ω1 is the measured value of the initial moisture content in the tailings of the water treatment plant, ω2 is the measured value of the initial moisture content in the slag, and P is the mixing ratio of the tailings and slag of the water treatment plant.

[0032] Preferably, in S5, an additional water volume M is required. w1 As shown below,

[0033]

[0034] Preferably, in S8, when the error value is within 0-5%, there is no need to add slag or water;

[0035] If the error exceeds 0-5%, add slag if the measured wet density of the mud is too low, and add water if the measured wet density of the mud is too high.

[0036] Preferably, in S9, the stirring time is 45-60 seconds.

[0037] Therefore, the present invention employs the above-mentioned fluidized solidified soil based on water treatment plant tailings and its preparation method, the beneficial effects of which are:

[0038] 1. This invention provides a mix design and calculation method based on the compounding of high-density soil material in water treatment plant tailings and slag. This method can solve the problems of high viscosity, lack of fluidity and water bleeding and shrinkage of high-density soil material in the preparation of fluidized solidified soil from water treatment plant tailings, and improve the quality of fluidized solidified soil, thereby increasing the source reduction and resource utilization rate of construction waste.

[0039] 2. This invention uses a mixture of tailings from water treatment plants and slag to prepare fluidized solidified soil. The use of fluidized solidified soil to replace traditional trench backfill materials improves the recycling rate of tailings from water treatment plants and reduces treatment costs.

[0040] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0041] Figure 1 This is a graph showing the wet density, flow value, and 28-day compressive strength of the mud in Example 1 of this invention.

[0042] Figure 2 This is a graph showing the curing material, flow value, and compressive strength in Example 1 of this invention.

[0043] Figure 3 This is a flowchart from Embodiment 1 of the present invention. Detailed Implementation

[0044] The present invention will be further described below with reference to the accompanying drawings and embodiments. Unless otherwise defined, the technical or scientific terms used in this invention should be understood in their ordinary sense by those skilled in the art. The features mentioned above or in the specific examples mentioned in this invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the invention and are not intended to limit the scope of the invention.

[0045] Example 1

[0046] like Figure 3 As shown, a method for preparing fluidized solidified soil based on water treatment plant tailings includes the following steps:

[0047] S1. Plot a graph of mud wet density - flow value - 28-day compressive strength with mud wet density as the x-axis and flow value and 28-day compressive strength as the y-axis, as follows: Figure 1 As shown.

[0048] S2. Based on the required flowability of 120-160mm and 28-day compressive strength of 0.6MPa, select the first overlapping shaded area from the mud wet density-flowability-28-day compressive strength graph obtained in S1. Then, select the maximum value of the mud wet density within this first overlapping shaded area, ρ. t =1.65t / m 3 .

[0049] S3. Plot a graph of cured material - flow value - compressive strength with the mass of cured material on the x-axis and the flow value and 28-day compressive strength on the y-axis, as shown below. Figure 2 As shown.

[0050] S4. Based on the flow value and 28-day compressive strength in the construction requirements, select the second overlapping shaded area in the cured material-flow value-compressive strength graph obtained in S3. Select the minimum mass of the cured material in the second overlapping shaded area, M. c =150kg.

[0051] S5. Determine the initial moisture content ω1 of the tailings sludge from the water treatment plant (80%) and the initial moisture content ω2 of the slag (15%). Test the specific gravity of the soil particles according to GB / T 50123 "Standard for Geotechnical Testing Methods". The specific gravity of the soil particles at this point is G. s =2.579, specific gravity of cured material G c =3.0.

[0052] Calculate the required amount of tailings sludge, slag, theoretical water consumption, and additional water to be added per cubic meter of fluidized solidified soil at the wet density of the sludge obtained in S2.

[0053] In S5, the theoretical water consumption is calculated as follows.

[0054]

[0055] Among them, M w G represents the theoretical water consumption. s M represents the specific gravity of soil particles after the mixture of tailings and slag from a water treatment plant. c G represents the amount of curing material added. c ρ is the specific gravity of the cured material. t This refers to the wet density of the mud.

[0056] In S5, the total mass of tailings and slag from the water treatment plant is calculated as follows.

[0057] M s =ρ t ×1000-M w -M c =1650-602-150=898kg;

[0058] Among them, M s This refers to the total mass of tailings and slag from the water treatment plant.

[0059] Quality M of tailings sludge from water treatment plant s1 The calculation is shown below.

[0060]

[0061] The quality M of the slag s2 The calculation is shown below.

[0062]

[0063] Wherein, ω1 is the measured value of the initial moisture content in the tailings of the water treatment plant, ω2 is the measured value of the initial moisture content in the slag, and P is the mixing ratio of the tailings and slag of the water treatment plant.

[0064] In S5, because the tailings and slag from the water treatment plant contain moisture, the additional water required needs to be calculated by subtracting this moisture content from the theoretical water consumption. The additional water required is M. w1 As shown below,

[0065]

[0066] S6. Based on the sludge mass of the water treatment plant calculated in S5 and the additional water required, put both into a ball mill to dissolve the sludge. After dissolving the sludge, put it into a storage tank and continue stirring.

[0067] S7. Add the slag and soil to the slurry storage tank in S6 according to the slag and soil mass calculated in S5. After continuous stirring, measure the wet density of the slurry. The measured wet density of the slurry is 1.66 t / m³. 3 .

[0068] S8. Based on the measured value of mud wet density obtained in S7 and the maximum value of mud wet density in S2, the error value is calculated to be 1%. Based on the error value, it is selected whether to add slag or water to obtain the final mixed mud.

[0069] In S8, when the error value is within 0-5%, no slag or water needs to be added;

[0070] If the error value exceeds 0-5%, add slag if the measured wet density of the mud is too low, and add water if the measured wet density of the mud is too high, to adjust the error value to within 0-5%.

[0071] S9. Extract the mixed slurry from S8, add the solidification material and stir for 50 seconds until uniformly mixed to obtain fluidized solidified soil.

[0072] The solidification material consists of: 36 kg of cement, 48 kg of mineral powder, 42 kg of fly ash, 6 kg of calcium hydroxide, 15 kg of calcium sulfate, 1.5 kg of surfactant, and 1.5 kg of water-reducing agent.

[0073] Comparative Example 1

[0074] The difference from Example 1 is that the mass of the water treatment plant tailings added is 1500 kg, no slag or additional water is added, and everything else is the same as in Example 1, resulting in fluidized solidified soil.

[0075] Comparative Example 2

[0076] The difference from Example 1 is that the mass of the added slag is 1032 kg, the amount of water to be added is 465 kg, and the tailings from the water treatment plant are not added. Everything else is the same as in Example 1, resulting in fluidized solidified soil.

[0077] Test Example 1

[0078] The flow value, bleeding rate and 28-day compressive strength of the fluidized solidified soil in Example 1 and Comparative Examples 1-2 were tested, and the results are shown in Table 1.

[0079] Table 1. Performance data of fluidized solidified soil in Example 1 and Comparative Examples 1-2

[0080]

[0081] Therefore, the present invention adopts the above-mentioned fluidized solidified soil based on water treatment plant tailings and its preparation method, and provides a mix design and calculation method based on the compounding of high-density soil material in water treatment plant tailings and slag soil. This can solve the problems of high viscosity, lack of fluidity and high-density soil material bleeding and settling in the preparation of fluidized solidified soil from water treatment plant tailings, and improve the quality of fluidized solidified soil, thereby increasing the source reduction and resource utilization rate of construction waste.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A fluidified soil based on purified water plant sludge, characterized in that: The components include tailings of water purification plant 10-80 parts, slag 50-100 parts and solidifying material 16-28 parts by mass fraction; The components in the solidifying material are cement 15-32%, mineral powder 31-32%, fly ash 22-38%, calcium hydroxide 4-5%, calcium sulfate 7-12%, surfactant 1-2% and water reducing agent 1-2% by mass percentage; The tailings of water purification plant and the slag are used to prepare the fluid solidified soil, the fluid solidified soil is used to replace the traditional pipe trench backfill material, and the high viscosity, lack of fluidity and high density soil material bleeding and sinking of the tailings of water purification plant are solved. The preparation method of the fluid solidified soil based on the tailings of water purification plant includes the following steps, S1, a mud wet density-flow value-28d compressive strength diagram is drawn with the mud wet density as the horizontal coordinate and the flow value and the 28d compressive strength as the vertical coordinate; S2, according to the flow value and the 28d compressive strength in the construction requirement, the superimposed shadow area one in the mud wet density-flow value-28d compressive strength diagram obtained in S1 is selected, and the maximum value of the mud wet density in the superimposed shadow area one is selected; S3, a solidifying material-flow value-compressive strength diagram is drawn with the mass of the solidifying material as the horizontal coordinate and the flow value and the compressive strength as the vertical coordinate; S4, according to the flow value and the 28d compressive strength in the construction requirement, the superimposed shadow area two in the solidifying material-flow value-compressive strength diagram obtained in S3 is selected, and the minimum value of the mass of the solidifying material in the superimposed shadow area two is selected; S5, the initial water content in the tailings of water purification plant and the initial water content in the slag are respectively measured, and the mass of the tailings of water purification plant, the mass of the slag, the theoretical water consumption and the additional water consumption required for each cubic fluid solidified soil under the mud wet density obtained in S2 are calculated; S6, the tailings of water purification plant and the additional water are put into a ball mill according to the mass and the additional water consumption calculated in S5, the tailings of water purification plant are disintegrated, and the disintegrated tailings of water purification plant are put into a slurry storage tank for continuous stirring; S7, the slag is added to the slurry storage tank in S6 according to the mass calculated in S5, and the mud wet density is measured after continuous stirring; S8, the error value is calculated according to the measured value of the mud wet density obtained in S7 and the maximum value of the mud wet density in S2, and whether the slag or water is added is selected according to the error value to obtain the final mixed mud slurry; When the error value is within 0-5%, the slag or water does not need to be added; If the error value exceeds 0-5%, if the measured value of the mud wet density is small, the slag is added, and if the measured value of the mud wet density is large, the water is added; S9, the mixed mud slurry in S8 is extracted, the solidifying material is added and stirred, and the fluid solidified soil is obtained after uniform stirring.

2. The fluidified soil based on sludge from water purification plants according to claim 1, characterized in that: The components include tailings of water purification plant 10-80 parts, slag 50-100 parts and solidifying material 16-28 parts by mass fraction; 3. The fluidified soil based on sludge from water purification plants according to claim 1, characterized in that: The components in the solidifying material are cement 15-32%, mineral powder 31-32%, fly ash 22-38%, calcium hydroxide 4-5%, calcium sulfate 7-12%, surfactant 1-2% and water reducing agent 1-2% by mass percentage; 4. The fluidified soil based on sludge from water purification plants according to claim 1, characterized in that: In S9, the stirring time is 45-60s.

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