Fluidized solidified soil prepared using engineering waste slag, equipment and method

Abstract

The present invention relates to the field of fluidized solidified soil, and specifically to fluidized solidified soil prepared from construction waste slag, equipment, and methods. The fluidized solidified soil comprises a drying and dehydration pretreatment unit, a slag feeding unit, a cementing material feeding unit, an admixture feeding device, a water supply system, and a stirring and mixing device. The preparation method comprises: spreading the preliminarily dehydrated slag into a uniform layer and feeding it into a multi-stage temperature-controlled belt drying oven, where it is dried to a moisture content of less than 15% using a combination of solar energy and an auxiliary heat source; after screening, crushing, and homogenization, the slag is mixed and stirred in proportion with cement, fly ash, and admixtures under mechanical linkage control to form a slurry with an expansion of 300 to 600 mm, which is then transported to the construction area for pouring and curing. The present invention solves the problems of existing fluidized solidified soil preparation technologies, such as the high moisture content of the slag, which makes it difficult to handle; the lack of a dedicated drying step, which makes it difficult to control the proportion; and the uneven material particles and low mixing efficiency.

Description

Technical Field

[0001] The present invention relates to the field of fluidized solidified soil, and in particular to fluidized solidified soil prepared by utilizing engineering waste slag, equipment and method. Background Art

[0002] Directly using large amounts of excavated soil for backfill often leads to potential settlement risks and construction quality issues due to high water content, uneven particle size, and difficulty compacting. Fluidized solidified soil is a new type of backfill material that has emerged in this context. By adding a curing agent (such as cement) and an appropriate amount of water to waste soil (mud), the mixture is stirred into a fluid, self-compacting slurry that can be pumped into the filling space. It is suitable for backfilling in difficult-to-compact areas such as narrow foundation pits, pipe trenches, and abutments. This material solves the problem of uniform compaction associated with traditional backfill soil and has potential for application in road subgrades and building foundation reinforcement.

[0003] However, the existing fluidized solidification soil preparation technology still has many shortcomings:

[0004] 1. The soil has high moisture content and is difficult to handle;

[0005] 2. There is no special drying process, and the ratio is difficult to control;

[0006] 3. The material particles are uneven and the mixing efficiency is low. Summary of the Invention

[0007] Based on the above description, the present invention provides a fluidized solidified soil, equipment and method prepared using engineering waste slag to solve the problems in the existing fluidized solidified soil preparation technology, such as high moisture content of the slag, difficulty in handling; lack of a special drying link, difficulty in controlling the ratio; uneven material particles and low mixing efficiency.

[0008] On the one hand, the present invention solves the above-mentioned technical problem with the following technical solution: a device for preparing fluidized solidified soil using engineering waste soil, comprising:

[0009] Drying and dehydration pretreatment unit, used for pretreatment of slag;

[0010] The slag feeding unit is used to receive and transport the engineering waste slag that has been pre-treated by dehydration;

[0011] Cementing material feeding unit, including auxiliary material silo and discharging mechanism;

[0012] An admixture supply device, used for adding admixtures;

[0013] Water supply system, used to provide mixing water;

[0014] A stirring and mixing device is connected to the above-mentioned slag feeding unit, cementing material feeding unit, admixture feeding device and water supply system, and stirs and mixes the raw materials;

[0015] The drying and dehydration pretreatment unit comprises:

[0016] A shaping module and a drying module are used to make the thickness of the feed layer consistent, as well as a solar heating module and an auxiliary heat source module for providing thermal energy, and a hot air circulation system for recovering hot and humid exhaust gas.

[0017] In the above technical solution, by setting up a drying and dehydration pretreatment unit, the moisture content of the slag can be significantly reduced, the adaptability of the raw materials can be improved, the dependence on the amount of binder can be reduced, and the stability and energy efficiency of the preparation process can be enhanced; the shaping module in the drying unit realizes uniform spreading of the slag, which helps to evenly penetrate the hot air, improves the drying efficiency and consistency of material processing; the multi-stage temperature-controlled drying module combines the solar heating module and the auxiliary heat source module to form a dual heat source system with energy saving and all-weather continuous operation capabilities; the hot air circulation system recovers heat from the exhaust gas, improves the energy utilization rate of the system, and reduces operating costs; the slag feeding, binder feeding, admixture addition and water supply systems are connected to the stirring and mixing device through the structure to realize continuous, stable and proportional transportation of each component, which helps to obtain a fluidized solidified soil slurry with consistent performance; the stirring and mixing device can realize efficient mixing of various materials, ensure the uniformity of the slurry and good construction performance, and is suitable for engineering application scenarios such as on-site backfill and foundation reinforcement;

[0018] The equipment has a reasonable structure and integrates pretreatment, quantitative feeding and mixing and molding. It is suitable for the preparation of efficient fluidized solidified soil in the process of resource utilization of engineering waste slag, and has beneficial effects such as low energy consumption, strong adaptability and high degree of continuity.

[0019] On the basis of the above technical solution, the present invention can also be improved as follows.

[0020] Furthermore, the drying module includes: a sealed drying box, a high-temperature resistant mesh belt conveyor device and its tensioning and correcting structure arranged in the drying box, and a plurality of independently temperature-controlled drying sections are arranged in sequence along the conveying direction of the mesh belt conveyor device to form a multi-stage temperature zone distribution, so as to continuously dry the slag in stages;

[0021] The hot air supply module supplies hot air through the air inlet at the lower part of the drying box body, and discharges moisture through the moisture outlet at the upper part of the drying box body, so that the hot air passes through the slag material layer for drying;

[0022] The solar heating module includes an air collector, a fan and an air valve, which are used to provide hot air as a primary heat source required for drying;

[0023] The auxiliary heat source module includes an electric heater or a gas hot air furnace, the air outlet of which is connected to the drying box and is connected in parallel with the solar heating module. It has a temperature control automatic switching function. When the hot air provided by the solar heating module is insufficient to maintain the set temperature of each drying section, the auxiliary heat source module automatically starts operation to provide supplementary hot air for the drying box.

[0024] Through the above technical solution, the drying box adopts a closed structure, and a high-temperature resistant mesh belt conveyor is installed inside, and a tensioning and correcting structure is provided, which can realize stable transportation and precise control of the slag during the drying process, avoid deviation or slippage, and improve the reliability of equipment operation; a plurality of independent temperature-controlled drying sections are set along the material conveying direction to form a multi-section temperature zone distribution, which can implement staged heating and drying according to the change of the moisture content of the slag, effectively avoid local overheating or insufficient drying, and significantly improve the drying uniformity and energy efficiency; hot air is fed into the bottom of the box and discharged from the top, ensuring that the hot air vertically penetrates the slag material layer, enhancing the heat and moisture exchange efficiency, shortening the drying time, and inhibiting The solar heating module provides heat through an air collector and fan system, and can operate as the main heat source under sunshine conditions, reducing dependence on fossil energy and having significant energy-saving and emission-reduction advantages. The auxiliary heat source module is connected in parallel with the solar system and has an automatic temperature control switching function. It can intelligently determine whether to start the supplementary heat device based on the actual heating temperature, ensuring that the drying section is always within the set temperature zone and ensuring continuous and stable operation. The overall structure realizes the complementary synergy between solar energy and auxiliary heat sources, adapting to the needs of soil drying in all weather and different climatic conditions, and improving the system's continuous operation capability and energy utilization efficiency.

[0025] This drying module has significant technical advantages in energy saving, drying efficiency, system adaptability and operational safety, and is suitable for resource processing of engineering waste.

[0026] Furthermore, the auxiliary heat source module and the air outlet of the solar heating module are connected in parallel through a T-shaped pipe, and the T-shaped pipe is provided with a one-way check valve and an electric air valve to prevent hot air backflow and realize automatic switching of the heat source.

[0027] The above technical solution connects the outlets of the auxiliary heat source module and the solar heating module in parallel to the same T-shaped pipe, so that the two heat sources can share a set of hot air transmission paths, achieving structural simplification and universal components, which is conducive to system integration and compact layout; a one-way check valve is set on the T-shaped pipe, which can effectively prevent the hot air of one heat source from flowing back into the other heat source system when it is working, avoiding energy waste and system cross pressure interference, and improving operational stability and safety; an electric air valve is set and linked to the temperature control system, which can automatically open or close the corresponding heat source channel according to the real-time temperature of the drying area, thereby realizing intelligent switching control of the heat source and improving the level of automation; while ensuring continuous and stable hot air supply, the structure can dynamically respond to changes in external conditions such as sunlight intensity or temperature fluctuations, so that the solar heat source works first and the auxiliary heat source is started only when necessary, thereby maximizing the advantages of renewable energy and reducing operating energy consumption; the overall system has high energy utilization efficiency and thermal control accuracy, strong adaptability, and is particularly suitable for segmented drying processes with high temperature control requirements, ensuring stable drying quality and reliable system operation;

[0028] The heat source switching structure is rationally designed and has the advantages of anti-backflow, safe switching, and energy-saving operation. It is a key control unit suitable for multi-source heating and drying systems.

[0029] Furthermore, the temperature control switching function is realized by a temperature sensor arranged in each drying section and an electric switch control circuit connected thereto. The control circuit is used to determine whether the current temperature is lower than a set threshold and control the start and stop of the auxiliary heat source module.

[0030] The above technical solution uses temperature sensors to monitor the operating temperature of each drying section in real time, accurately obtaining the hot air environment status within the area, ensuring the drying process is under control and avoiding unstable drying quality due to temperature fluctuations. The temperature sensor can be a non-contact temperature sensor of model ES1B.

[0031] The temperature sensor is connected to the electric switch control circuit to realize temperature control logic closed-loop control, which can compare and judge the actual detected temperature with the preset threshold and accurately trigger the control instruction; when the system detects that the temperature of the drying section is lower than the set lower limit, the control circuit immediately outputs the start-stop signal and automatically activates the auxiliary heat source module to put it into operation to ensure that the drying temperature zone is maintained within the target range; this temperature control switching function has the advantages of fast response speed, high control accuracy, and high degree of system operation automation. It can dynamically adjust the degree of auxiliary heat source participation according to the solar heating effect to achieve intelligent coordination of heat sources; the overall system can complete temperature identification and heat source switching without human intervention, effectively improving the continuity and stability of drying operations, reducing manual control errors and energy waste, and helping to optimize energy utilization under different environmental conditions (such as day and night, cloudy and sunny weather), and improving the adaptability and operation efficiency of the drying system.

[0032] In another aspect, the present invention solves the above-mentioned technical problem with the following technical solution: a method for preparing fluidized solidified soil based on engineering waste soil, using the above-mentioned equipment to prepare fluidized solidified soil, comprising the following steps:

[0033] The preliminarily dehydrated soil is spread into a uniform layer and sent to a multi-stage temperature-controlled belt drying oven, where it is dried using a combination of solar energy and auxiliary heat sources until the moisture content is less than 15%.

[0034] After screening, crushing and homogenization, it is mixed with cement, fly ash, admixtures, etc. in proportion under mechanical linkage control to form a slurry with an expansion of 300 to 600 mm, and then transported to the construction area for casting and curing.

[0035] Furthermore, in the drying step, the slag moves at a uniform speed of 0.1 to 0.5 m / min along with a high-temperature resistant metal mesh belt, the transverse width of the mesh belt is not less than 800 mm, and the drying time is adjusted to 15 to 40 minutes according to the initial moisture content of the slag.

[0036] Furthermore, the drying box is provided with no less than three independent drying sections along the direction of soil movement, each section is provided with an independent hot air supply channel and temperature controller, and the drying temperature zones are: the first section 40-60°C, the second section 60-80°C, and the third section 80-100°C.

[0037] Furthermore, the screening process uses two layers of vibrating screens, the first layer has a sieve hole size of 20 mm for removing large aggregates, and the second layer has a sieve hole size of 10 mm for screening qualified fine materials. The homogenization process uses a crushing mechanism equipped with a rotating deagglomerating blade shaft with a rotation speed of 300 to 600 rpm.

[0038] Furthermore, in the batching and mixing step, the main material spiral conveying shaft is provided with a cam plate, and the cam is connected to the cement powder silo gate, fly ash feeder and volumetric water pump through a connecting rod mechanism. As the main material conveying rotation angle drives the various auxiliary materials to be opened synchronously and quantitatively, realizing preset proportional linkage control.

[0039] The above technical solution first spreads the preliminarily dehydrated soil into a uniform layer of 3 to 10 cm, conveys it on a metal mesh belt at a uniform speed of 0.1 to 0.5 m / min, and then enters the drying box and sequentially passes through three temperature zones of 40 to 100°C for drying. This effectively reduces the soil moisture content to below 15%, improving drying uniformity and thermal energy utilization.

[0040] Secondly, a double-layer vibrating screen and a crushing device equipped with a de-agglomerating blade shaft are used to screen and homogenize the dried slag, removing large particles and mud clumps to ensure particle size consistency and provide protection for slurry stability.

[0041] Secondly, by installing a cam plate on the main material screw conveying shaft, the cement powder silo gate, fly ash discharger and volumetric pump are driven in a linked manner, so that the auxiliary materials can be added synchronously and quantitatively according to the main material conveying status, thus constructing a mechanical batching system that does not require electronic control, with high batching accuracy, fast response, and stability and reliability.

[0042] Finally, a fluidized solidified soil slurry with an expansion of 300 to 600 mm is formed, which has good pumpability and construction adaptability. It is suitable for on-site backfilling of foundation pits, trenches, etc., and improves the efficiency of soil resource utilization.

[0043] In the third aspect, the present invention solves the above technical problems with the following technical solutions: A composition for preparing fluidized solidified soil, comprising the following components in percentage by mass:

[0044] 55% to 75% of the construction waste soil is

[0045] Cement 8% to 15%,

[0046] Fly ash 5% to 20%,

[0047] Expansion agent 1% to 5%,

[0048] Water reducing agent 0.2%~0.8%,

[0049] The rest is water,

[0050] After being stirred, the composition forms a pumpable solidifying slurry having an expansion of 300 to 600 mm and a 7-day compressive strength of not less than 0.5 MPa.

[0051] Compared with the prior art, the technical solution of this application has the following beneficial technical effects:

[0052] 1. The present invention adopts a three-stage temperature-controlled drying structure, combined with solar air heating and an intelligent switching system for auxiliary heat sources. It can achieve differentiated temperature zone treatment according to changes in soil moisture content, avoiding the problem of surface dryness and internal wetness in traditional blast drying. At the same time, it uses solar energy for priority heating and automatic supplementation of auxiliary heat sources to effectively reduce the energy consumption of gas or electric heating, achieve all-weather continuous operation, and have higher energy utilization efficiency than the existing single heat source system.

[0053] 2. Unlike the existing technology that uses simple screening, this method introduces a double-layer vibrating screen and a deagglomerating knife shaft device, which can not only effectively remove coarse aggregates and agglomerated particles, but also stably control the particle size of the slag fine material within the set range, improve the homogeneity of the raw materials, help to mix the slurry evenly and ensure pumping stability, and significantly improve the construction performance of fluidized solidified soil.

[0054] 3. Unlike common PLC or flow sensor control methods, this invention utilizes a main screw conveyor shaft to drive a non-circular cam disc, which, through a linkage mechanism, synchronously controls the supply of cement, fly ash, and water, achieving purely mechanical, synchronized, and quantitative dosing. This method offers intuitive structure, rapid response, and adaptability to complex field environments. It is particularly well-suited for low-power, field, or mobile operations, and exhibits excellent stability and anti-interference capabilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is a schematic diagram of the overall structure of an apparatus for preparing fluidized solidified soil using engineering waste soil, provided in Example 1 of the present invention;

[0056] Figure 2 A schematic side structural diagram of a drying module of an apparatus for preparing fluidized solidified soil using engineering waste provided in Example 1 of the present invention;

[0057] Figure 3 A schematic structural diagram of a drying module of an apparatus for preparing fluidized solidified soil using engineering waste slag provided in Example 1 of the present invention;

[0058] Figure 4 A schematic structural diagram of the feed end of a drying module of an apparatus for preparing fluidized solidified soil using engineering waste provided in Example 1 of the present invention;

[0059] Figure 5 This is a schematic diagram of a method for preparing fluidized solidified soil based on engineering waste provided in Example 2 of the present invention.

[0060] Reference numerals: 1, drying and dehydration pretreatment unit; 11, shaping module; 12, drying module; 13, solar heating module; 14, auxiliary heat source module; 15, hot air circulation system;

[0061] 2. Slag feeding unit; 3. Cementing material feeding unit;

[0062] 4. Additive supply device;

[0063] 5. Water supply system;

[0064] 6. Stirring and mixing device;

[0065] 71. Drying box; 72. Mesh belt conveyor;

[0066] 81. Air collector; 82. Fan; 83. Air valve; 84. T-shaped pipe. DETAILED DESCRIPTION

[0067] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0068] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. Example 1:

[0069] refer to Figure 1 and Figure 4 , a device for preparing fluidized solidified soil using engineering waste soil, comprising:

[0070] Drying and dehydration pretreatment unit, used for pretreatment of slag;

[0071] The slag feeding unit is used to receive and transport the engineering waste slag that has been pre-treated by dehydration;

[0072] Cementing material feeding unit, including auxiliary material silo and discharging mechanism;

[0073] An admixture supply device, used for adding admixtures;

[0074] Water supply system, used to provide mixing water;

[0075] A stirring and mixing device is connected to the above-mentioned slag feeding unit, cementing material feeding unit, admixture feeding device and water supply system, and stirs and mixes the raw materials;

[0076] The drying and dehydration pretreatment unit comprises:

[0077] A shaping module and a drying module are used to make the thickness of the feed layer consistent, as well as a solar heating module and an auxiliary heat source module for providing thermal energy, and a hot air circulation system for recovering hot and humid exhaust gas.

[0078] Preferably, the drying and dehydration pretreatment unit is the first functional module of the entire equipment. Its main function is to carry out continuous and controllable deep dehydration and drying treatment of engineering waste soil to achieve the moisture content and particle size requirements of the subsequent mixing and slurrying process. Specifically, it includes a shaping module and a drying module for making the thickness of the feed layer uniform, as well as a solar heating module and an auxiliary heat source module for providing heat energy, and a hot air circulation system for recovering hot and humid exhaust gas:

[0079] As a preferred feed shaping module, the soil after initial dehydration is generally wet material pre-treated in a filter press or natural sedimentation tank. Its moisture content is still relatively high (approximately 30-40%), and it is in the form of lumps or irregular blocks with uneven particle size distribution. To ensure subsequent drying efficiency and uniformity, a feed shaping module is required to perform thickness-setting and shaping.

[0080] This module includes:

[0081] Belt conveyor system: stably transports the soil to the distributor entrance;

[0082] Horizontal swinging spreader: This mechanism drives the spreading opening to swing back and forth left and right through the eccentric wheel, so as to achieve uniform horizontal spreading of the material on the mesh belt;

[0083] Vibrating screed or scraper leveling device: located at the end of the distributor, used to level the accumulated debris and control its thickness to form a uniform material layer of 3 to 5 cm.

[0084] The material width is set to 1000mm to match the width of the drying conveyor belt. The control system adjusts the swing amplitude via a limiter to ensure a consistent width of soil coverage. After the material layer is shaped, its thickness error is controlled within ±5mm, ensuring uniform penetration of the hot air.

[0085] As an optimal drying module structure and temperature control design, the shaped soil is dropped through the distribution system onto a continuously running high-temperature resistant conveyor belt. The conveyor belt then enters the sealed drying chamber for complete drying. This drying module is the core component of this system, utilizing a combination of multiple temperature zones, countercurrent hot air, and controlled conveying to achieve efficient, phased drying.

[0086] The drying box is a long, enclosed steel box with a 12-meter-long stainless steel mesh belt conveyor system. The mesh belt is made of 316L stainless steel woven mesh, which has excellent corrosion resistance and high temperature resistance. The mesh belt is equipped with:

[0087] Hydraulic tensioning system prevents the mesh belt from loosening due to thermal expansion and contraction;

[0088] The automatic deviation-correcting roller device can adjust the belt direction in real time to ensure stable operation.

[0089] The drying box is divided into three independently temperature-controlled heating sections along the conveying direction:

[0090] The first preheating and drying zone (the first 3 meters): The hot air temperature is set at 40-60°C to achieve initial heating and low-speed dehydration of the wet soil;

[0091] The second main drying area (6 meters in the middle): The temperature is set at 60-80°C to quickly evaporate most of the water;

[0092] The third section of enhanced dehydration area (the last 3 meters): the temperature is set at 80-100°C to further reduce the moisture content to below the target value.

[0093] Each heating zone is equipped with an independent temperature sensor and fan system, which can automatically adjust the air volume and heating power according to the temperature fluctuation of the material layer, ensuring a stable gradient between the three temperature zones, realizing a progressive drying process, and avoiding agglomeration or surface hardening caused by sudden temperature changes.

[0094] Hot air enters from the bottom of the box, passes through the slag layer and is discharged from the top dehumidification port, forming a bottom-up countercurrent penetrating heat exchange method, which can improve the drying efficiency by more than 30%.

[0095] As the preferred heat source system and intelligent switching control, in response to the green energy-saving design concept, this equipment adopts a combined heat source system of "solar heat collection + auxiliary heat source supplement".

[0096] Solar heating system: The top of the drying chamber is equipped with multiple air collectors, each covering an area of ​​at least 20 square meters. These collectors consist of a tempered glass cover, a black heat-absorbing aluminum plate with ribs, and an insulating back panel. Outdoor air, heated by sunlight, flows through the heat-absorbing plates and is then blown into the bottom of the drying chamber by a fan. Tests have shown that on sunny summer days, the collector output temperature can reach 75-85°C.

[0097] Auxiliary heat source system: When solar radiation is insufficient, such as at night or on rainy days, a gas-fired hot air furnace provides supplemental heat. The device's output hot air temperature is adjustable (control range: 100-120°C), meeting the high temperature requirements of the final enhanced dehydration zone.

[0098] The two heat sources are connected in parallel to the drying oven's main hot air duct using a "T-type three-way connection" system, a one-way check valve, and a motorized damper. The dampers control heat source switching based on actual temperature signals collected by thermocouples. When the system detects that the temperature in any drying zone falls below a set lower limit (e.g., 60°C), the auxiliary heat source automatically activates. When the temperature returns to the normal range (e.g., >70°C), the auxiliary heating automatically stops and solar heating resumes. The entire switching response time is less than 3 seconds.

[0099] This temperature control switching system ensures thermal stability throughout the drying process under different climates and day and night cycles, while significantly reducing operating energy consumption.

[0100] As a preferred option, exhaust gas emissions are combined with heat recovery. The hot and humid exhaust gases generated during the soil drying process are collected at the top of the chamber and passed through an air duct to a bag-type dust collector for dust purification, achieving a filtration efficiency exceeding 99%. The purified exhaust gas enters a heat recovery heat exchanger system, where the waste heat is transferred to the fresh air duct via an air-to-air heat exchanger, preheating the fresh air that will be fed into the collector or auxiliary heat source. Combined with the heat pump system to recover latent heat, this system's overall energy efficiency can be increased by approximately 40%.

[0101] The recovered hot air then enters the air collector or combustion-supporting air channel to form a closed-loop circulation, greatly reducing energy consumption and pollutant emissions.

[0102] Preferably, the slag feeding unit comprises a slag screw conveyor, a cam plate and a connecting rod system;

[0103] Specifically, the slag falls into the belt conveyor or screw conveyor in a quantitative manner from the discharge end of the drying and dehydration pretreatment unit, forming a slag supply path; the slag screw conveyor adopts a two-stage conveying structure with a screw diameter of Φ300mm. The first section is horizontally arranged for receiving materials, and the second section is a gently inclined ascending section, which is used to deliver the slag to the mixer feed port.

[0104] The slag screw conveyor is equipped with a drive motor and a reducer, which drives the horizontally arranged screw shaft to rotate at a set speed, and is used to quantitatively transport the dried slag to the mixer; the slag screw conveyor is driven by a motor and can be set to constant speed or variable speed operation. The end of its screw shaft is connected to a cam disk, which is used as a linkage trigger mechanism to control the proportion of auxiliary material addition; the outer contour of the cam disk is designed to be non-circular, and different circumferential positions correspond to different linkage response angles. The circumferential distribution of the "high point" and "low point" of the cam constitutes a complete cam cycle, which corresponds to the flow change rhythm of each rotation of the main material shaft, and realizes continuous adjustment of the auxiliary material addition rate during mechanical linkage batching.

[0105] The connecting rod system consists of a high-strength articulated rod, a slider mechanism and a return spring; one end maintains contact with the cam plate surface (usually equipped with a roller push rod); the other end is mechanically connected to the auxiliary material control components (such as cement gates, fly ash conveying motor start levers, and water control valve push rods).

[0106] In order to prevent the slag from being transported poorly due to fluctuations in water content or changes in bulk density, the main material hopper is equipped with a fluidizing vibrator or an adjustable sliding gate to adjust the fluidity and feeding rhythm.

[0107] Preferably, the cementitious material feeding unit includes a cement silo, a fly ash silo and a corresponding quantitative feeding mechanism, and the structure of the unit is as follows:

[0108] Cement and fly ash are each equipped with an independent vertical silo with a capacity of 1 to 3 tons and a conical discharge hopper at the bottom;

[0109] A small screw conveyor (diameter Φ100mm, length 1000mm) is installed at the bottom of each silo to quantitatively convey the cementing material;

[0110] The driving motor of the screw conveyor is connected to a transmission shaft with a movable bearing through a coupling, and the other end of the transmission shaft is connected to the connecting rod part of the main material shaft cam;

[0111] The rotation of the cam drives the connecting rod mechanism to push the conveying screw to rotate, realizing the proportional control logic of "the greater the main material conveying amount, the more auxiliary materials will follow synchronously";

[0112] The spiral feed pipe mouth is equipped with a limit ring and a buffer anti-backblocking gate, which can close automatically when blocked and prevent air backflow.

[0113] Working process: When the main material screw conveyor is running, the non-circular cam disc at the end of its shaft rotates synchronously.

[0114] The cam disc is in constant contact with the roller push rod of the connecting rod system. Since the profile of the cam is a non-constant radius, it drives the connecting rod to output a periodic reciprocating motion every time it rotates one circle.

[0115] This reciprocating motion drives the feeding mechanism of the auxiliary material system through mechanical coupling, for example:

[0116] When the cam is at the high point: the connecting rod stroke is the largest, the auxiliary material gate is pushed to open the maximum, and the positive displacement pump pumps the maximum amount;

[0117] When the cam is at the low point: the connecting rod stroke is the smallest, and the corresponding auxiliary material supply is also the smallest or zero.

[0118] The entire mechanical structure achieves the goal of synchronizing the auxiliary material supply rhythm with the main material delivery and proportional linkage, and different ratio models can be set by replacing cam discs with different profiles.

[0119] In order to adapt to different engineering requirements and material ratios, the system is equipped with the following adjustable mechanisms:

[0120] Cam disc quick release device: The spindle end is equipped with a tapered hole + keyway positioning structure to facilitate the replacement of cam discs with different contour shapes;

[0121] Slider limit structure: An adjustable limit block is set between the connecting rod and the feeding lever to set the maximum auxiliary material feeding opening;

[0122] Return spring stiffness adjustment: Adjusting the preload of the return spring can change the response sensitivity and stroke stability;

[0123] Multi-auxiliary material linkage structure: a set of cam discs can be connected to multiple auxiliary material systems through different connecting rods at the same time to achieve multiple groups of synchronous linkage.

[0124] Preferably, the cementitious material feeding unit includes a cement silo, a fly ash silo and a corresponding quantitative feeding mechanism, and the structure of the unit is as follows:

[0125] Cement and fly ash are each equipped with an independent vertical silo with a capacity of 1 to 3 tons and a conical discharge hopper at the bottom;

[0126] A small screw conveyor (diameter Φ100mm, length 1000mm) is installed at the bottom of each silo to quantitatively convey the cementing material;

[0127] The driving motor of the screw conveyor is connected to a transmission shaft with a movable bearing through a coupling, and the other end of the transmission shaft is connected to the connecting rod part of the main material shaft cam;

[0128] The rotation of the cam drives the connecting rod mechanism to push the conveying screw to rotate, realizing the proportional control logic of "the greater the main material conveying amount, the more auxiliary materials will follow synchronously";

[0129] The spiral feed pipe mouth is equipped with a limit ring and a buffer anti-backblocking gate, which can close automatically when blocked and prevent air backflow.

[0130] This feeding method does not require electronic weighing or PLC flow control system, and has good stability in outdoor hot, humid, dusty and low-maintenance conditions.

[0131] As a preference, in accordance with the performance requirements of the solidified soil such as fluidity and crack resistance in different engineering needs, it is necessary to add appropriate amounts of liquid or powdered admixtures such as water reducers and expansion agents. The admixture supply device in the present invention can be configured in two forms:

[0132] Liquid admixtures (such as water reducers) are pumped into the front section of the mixer via a corrosion-resistant positive displacement pump, injected simultaneously with the main and auxiliary materials. The pump's drive shaft is linked to the main material cam, and proportional adjustment can be achieved by changing the pump body's pump cavity volume or pump head stroke;

[0133] Powdered admixtures (such as expanders) are quantitatively released into the mixing chamber by a small screw feeder or a vibrating hopper, and the speed is controlled by the main shaft drive end to achieve synchronous proportioning.

[0134] The accuracy of admixture addition is controlled within ±3% to ensure the consistency and adaptability of the slurry mix ratio.

[0135] Preferably, in order to achieve the desired water-to-binder ratio and fluidity control, the water supply system of the present invention is provided with a closed-loop water supply system consisting of a water supply tank, a metering pump, a cam pump or an electric water valve. Its features are as follows:

[0136] The water tank is a heat-insulating polymer container with a capacity of ≥1 ton, which can store a stable water source;

[0137] The water outlet pipe is equipped with a positive displacement metering pump with an adjustable pump volume range (10~100 L / min), and the outlet is connected to the mixing chamber spray port;

[0138] The water pump control method is linked to the main material feeding cam structure, or a mechanical cam pump with a damping buffer is used to ensure that the water is dynamically synchronized with the changes in the main material;

[0139] The pipeline is equipped with a check valve, dust filter and exhaust valve to ensure the stable operation of the system without interference from dust.

[0140] As a preferred embodiment, the stirring and mixing device adopts a horizontal continuous double-shaft paddle mixer with the following structure:

[0141] The cylinder is a double-layer jacket structure, the outer shell is made of wear-resistant steel, and the inner lining is replaceable;

[0142] Two parallel stirring shafts are equipped with spiral propulsion blades and blade diversion guide plates, which can achieve compound mixing behaviors such as pushing, flipping, shearing and extrusion;

[0143] The stirring shaft speed is set to 30-60 rpm, the mixing time is 15-30 seconds, and the stirring power is 5-11 kW;

[0144] The feeding end is equipped with a three-level distribution trough, which can introduce the main material, auxiliary material, admixture and water into different mixing sections respectively to prevent premature reaction or agglomeration;

[0145] The discharge end is equipped with an adjustable flow rate gate, which is connected to a hose pump or a screw pump to ensure that the slurry is pumped within 10 minutes after stirring.

[0146] The mixer is supported on a base platform and can be equipped with wheels, hydraulic feet or modular assembly and disassembly interfaces according to site requirements, making it suitable for mobile deployment. Example 2:

[0147] refer to Figure 5 A method for preparing fluidized solidified soil based on engineering waste soil, using the equipment of Example 1 to prepare fluidized solidified soil, comprises the following steps:

[0148] S1) soil drying and pretreatment steps,

[0149] The preliminarily dehydrated soil (typically with a moisture content of approximately 30% to 40%) is first conveyed to the drying unit via a belt conveyor. To ensure uniform drying, a horizontally swinging spreader and scraper leveler are installed to spread the soil into a uniform layer with a thickness of 3 to 10 cm and a width of at least 800 mm before feeding it into a continuous belt drying chamber.

[0150] There are multiple temperature zones inside the drying box, which are divided into at least three independent temperature control zones according to the direction of soil movement:

[0151] The first temperature zone is controlled at 40-60°C and is used for preheating the slag;

[0152] The second temperature zone is set at 60-80℃ for main dehydration;

[0153] The third temperature zone is 80-100℃, which is used to enhance drying and ensure that the moisture content is controlled below 15%.

[0154] Hot air flows vertically from the bottom of the chamber through the material layer before being discharged through the moisture removal port at the top, creating a countercurrent flow field and improving drying efficiency. The soil moves along a high-temperature stainless steel mesh belt at a constant speed of 0.1 to 0.5 m / min. The drying time is set between 15 and 40 minutes, depending on the initial moisture content.

[0155] The drying heat source utilizes a parallel combination of a solar air collector and a gas-fired hot air furnace. Solar energy is prioritized during the day, automatically switching to gas heat at night. The system utilizes temperature-controlled air valves to achieve seamless heat source transitions. The hot, moist exhaust gas generated during the drying process is partially recovered through a bag filter and heat exchange system, improving energy efficiency.

[0156] S2) Screening, crushing and homogenization steps,

[0157] The dried soil enters the screening device via a belt conveyor. The screening device has two layers:

[0158] The first layer of sieve has a 20 mm sieve hole size, which is used to remove large aggregate particles larger than 20 mm;

[0159] The second layer of sieve has a size of 10 mm, which is used to select qualified fine materials for pulping.

[0160] Double-layer screening significantly improves the distribution stability of fine particles. Screened material is conveyed to a crushing mechanism equipped with a deagglomerating blade shaft, which rotates at a controlled speed of 300-600 rpm. This effectively breaks up dry soil clumps and further homogenizes the fine material particle size, making it suitable for continuous mixing pulping.

[0161] S3) Mechanical linkage batching and continuous mixing steps,

[0162] The homogenized fine soil material, serving as the main material, is fed into the mixing device via a screw conveyor. The screw conveyor shaft is equipped with a cam disc with a non-circular profile, which is mechanically connected to a connecting rod mechanism. The other end of the connecting rod is connected to the discharge gate at the bottom of the cement silo, the control lever of the fly ash screw feeder, and the control lever of the water supply positive displacement pump.

[0163] As the main material shaft rotates to transport slag, the cam disc rotates synchronously with the shaft, driving the aforementioned auxiliary material devices to feed materials synchronously according to its angle change, forming a linked and controlled proportional batching system. For example, every 360° rotation drives the precise addition of the corresponding proportions of cement (e.g., 20kg of main material to 2kg of cement), fly ash (e.g., 1kg), and water (e.g., 4kg), ensuring consistent and repeatable slurry proportions.

[0164] Admixtures (such as expanders, water reducers) can be injected through a small screw feeder or volumetric pump and added into the mixing chamber simultaneously with the main and auxiliary materials.

[0165] The mixing device uses a horizontal twin-shaft continuous impeller mixer with propulsion, shearing, and tumbling functions. The mixing time is controlled within 20 to 30 seconds to form a uniform fluid slurry. The slurry expansion is controlled within the range of 300 to 600 mm, meeting the fluidity requirements for on-site pouring.

[0166] S4) Slurry conveying and pouring molding steps,

[0167] The fluidized, solidified soil slurry formed by mixing is connected to a tubular hose pump through the discharge port and directly delivered to the construction backfill area, such as the trench base, foundation pit backfill layer, or foundation reinforcement space. During construction, the spindle speed can be adjusted in real time based on the slurry properties to adjust the output.

[0168] In the construction area, the slurry is naturally cured after preliminary vibration and surface leveling. It will initially set within 24 hours and form a structural consolidation layer with load-bearing capacity in 3 to 7 days, meeting the project requirements. Example 3:

[0169] A composition for preparing fluidized solidified soil, comprising the following components in percentage by mass:

[0170] 55% to 75% of the construction waste soil is

[0171] Cement 8% to 15%,

[0172] Fly ash 5% to 20%,

[0173] Expansion agent 1% to 5%,

[0174] Water reducing agent 0.2%~0.8%,

[0175] The rest is water,

[0176] The composition is stirred to form a pumpable solidifying slurry with an expansion of 300 to 600 mm and a 7-day compressive strength of not less than 0.5 MPa.

[0177] Engineering waste soil comes from construction excavation waste soil, foundation waste soil, non-polluting shield slag, etc. After drying, screening, crushing and homogenization, the particle size is less than 10 mm and the moisture content is less than 15%; the cement used is PO 42.5 ordinary Portland cement; the fly ash is Class II ash, which meets the "GB / T 1596" standard; the expansive agent is calcium oxide type or tricalcium aluminate type expansive agent; the water reducer is a polycarboxylic acid-based high-performance water reducer with a solid content ≥20%.

[0178] Performance goals:

[0179] Fluidity: The expansion is controlled between 300 and 600 mm, which can meet the pumping requirements of general delivery pumps at a pressure of 0.3 to 0.6 MPa;

[0180] Early strength: 7-day unconfined compressive strength is not less than 0.5 MPa;

[0181] Construction time: initial setting time is controlled within 2 to 4 hours;

[0182] Settlement stability: Settlement height difference <5 mm;

[0183] Volume stability: no obvious water seepage, no cracking, meeting the backfill settlement control standards.

[0184] Test items and methods:

[0185] (1) Slurry expansion: according to the fluidity determination method in GB / T 2419-2005;

[0186] (2) Compressive strength: According to GB / T 17671-2021, a 40×40×40 mm cube was made and tested after 7 days of curing;

[0187] (3) Initial setting time: according to the Vicat method in GB / T 1346-2011;

[0188] (4) Water seepage rate: observation method + filter paper method, record whether water seepage occurs from 0 to 60 minutes;

[0189] (5) Mud sedimentation difference, plastic graduated cylinder method, observe the change in the thickness of the supernatant after 3 hours;

[0190] (6) Pumpability: Try using a plunger pump or screw pump and test it at a conveying distance of 30 m.

[0191] Typical ratios and test results:

[0192]

[0193] in conclusion:

[0194] The A and C ratios performed well and were suitable for structural filling;

[0195] Mix B has better fluidity and is suitable for deep foundation pits or large trenches;

[0196] All compositions met the minimum performance requirements for elongation and compressive strength.

[0197] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A device for preparing fluidized solidified soil using engineering waste soil, characterized in that: include: Drying and dehydration pretreatment unit, used for pretreatment of slag; The slag feeding unit is used to receive and transport the engineering waste slag that has been pre-treated by dehydration; Cementing material feeding unit, including auxiliary material silo and discharging mechanism; An admixture supply device, used for adding admixtures; Water supply system, used to provide mixing water; A stirring and mixing device is connected to the above-mentioned slag feeding unit, cementing material feeding unit, admixture feeding device and water supply system, and stirs and mixes the raw materials; The drying and dehydration pretreatment unit comprises: A shaping module and drying module to ensure uniform thickness of the feed layer, a solar heating module and an auxiliary heat source module to provide heat energy, and a hot air circulation system to recover hot and humid exhaust gas; The drying module includes: a sealed drying box, a high-temperature resistant mesh belt conveyor device and its tensioning and correcting structure arranged in the drying box, and a plurality of independently temperature-controlled drying sections are arranged in sequence along the conveying direction of the mesh belt conveyor device, forming a multi-stage temperature zone distribution, and continuously drying the soil in stages; The hot air supply module supplies hot air through the air inlet at the bottom of the drying box and discharges moisture through the moisture outlet at the top of the drying box, so that the hot air passes through the slag layer to dry the slag layer. The solar heating module includes an air collector, a fan and an air valve, which are used to provide hot air as a primary heat source required for drying; The auxiliary heat source module includes an electric heater or a gas hot air furnace, the air outlet of which is connected to the drying box and is connected in parallel with the solar heating module. It has a temperature control switching function. When the hot air provided by the solar heating module is insufficient to maintain the set temperature of each drying section, the auxiliary heat source module automatically starts to operate and provides supplementary hot air for the drying box. The temperature control switching function is realized by the temperature sensor set in each drying section and the electric switch control circuit connected thereto. The control circuit is used to determine whether the current temperature is lower than the set threshold and control the start and stop of the auxiliary heat source module.

2. The device according to claim 1, characterized in that The auxiliary heat source module and the air outlet of the solar heating module are connected in parallel through a T-shaped pipe. The T-shaped pipe is provided with a one-way check valve and an electric air valve to prevent the backflow of hot air and realize automatic switching of the heat source.

3. A method for preparing fluidized solidified soil based on engineering waste soil, characterized in that: The fluidized solidified soil is prepared using the device according to any one of claims 1 to 2, comprising the following steps: The preliminarily dehydrated soil is spread into a uniform layer and sent to a multi-stage temperature-controlled belt drying oven, where it is dried using a combination of solar energy and auxiliary heat sources until the moisture content is less than 15%. After screening, crushing and homogenization, it is mixed with cement, fly ash and admixtures in proportion under mechanical linkage control to form a slurry with an expansion of 300-600mm, and then transported to the construction area for pouring and curing. In the batching and mixing step, the main material spiral conveying shaft is provided with a cam plate, and the cam is connected to the cement powder silo gate, fly ash feeder and volumetric water pump through a connecting rod mechanism. As the main material conveying rotation angle drives the various auxiliary materials to be opened synchronously and quantitatively, realizing the preset proportional linkage control.

4. The method according to claim 3, characterized in that During the drying process, the slag moves along a high-temperature resistant metal mesh belt at a uniform linear speed of 0.1 to 0.5 m / min. The transverse width of the mesh belt is not less than 800 mm. The drying time is adjusted to 15 to 40 minutes according to the initial moisture content of the slag.

5. The method according to claim 3, characterized in that The drying box is provided with no less than three independent drying sections along the direction of soil movement. Each section is provided with an independent hot air supply channel and temperature controller. The drying temperature zones are: 40-60°C in the first section, 60-80°C in the second section, and 80-100°C in the third section.

6. The method according to claim 3, characterized in that The screening process uses two layers of vibrating screens. The first layer has a sieve hole size of 20 mm, which is used to remove large aggregates. The second layer has a sieve hole size of 10 mm, which is used to screen qualified fine materials. The homogenization process uses a crushing mechanism equipped with a rotating deagglomerating knife shaft with a rotation speed of 300 to 600 rpm.

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