Sand-containing loess high-concentration grading slurry system and method

Abstract

The application discloses a high-concentration graded sand-containing loess slurry system and method. The application adopts a gradient material screening process and a gradient material slurry mixing process, and realizes high-concentration mixed slurry of multiple-component materials. In the high-concentration loess slurry of the application, the loess content is higher, and after being combined with cement and other cementitious materials, more cementing materials can be formed, so that the slurry has higher strength after solidification, and better meets the requirements of engineering on reinforcement and bearing capacity; the particles of the high-concentration slurry are more compact, and the porosity is lower, so that after being poured into the stratum, the permeation of water and other fluids can be effectively prevented, the waterproof performance of the engineering is improved, and better impermeability is achieved.

Description

Technical Field

[0001] This invention relates to the field of disaster prevention and control technology in coal mining, and in particular to a high-concentration gradation slurry preparation system and method for sandy loess. Background Technology

[0002] In the field of civil engineering, especially in foundation treatment, tunnel engineering, and underground engineering, grout is often used to improve the physical and mechanical properties of soil, enhancing its strength and stability. Traditional cement grout suffers from drawbacks in some engineering applications, including high cost, strict requirements for environmental humidity, and limited adaptability to certain special geological conditions. Loess, a special soil type widely distributed in Northwest my country, is characterized by its large porosity, high permeability, and tendency to disintegrate when exposed to water. Using loess as part of the grout preparation material can fully utilize the abundant local loess resources, reducing engineering costs. Furthermore, the addition of cement can improve the grout's strength and bonding performance.

[0003] The current loess slurry has the following technical problems:

[0004] Poor slurry uniformity: Loess particles have a wide particle size distribution, and different particle sizes have different densities and settling velocities, which easily leads to sedimentation and stratification during the slurry preparation process, resulting in uneven slurry composition. Solving this problem usually requires increasing the power and mixing time of the mixing equipment, but this increases energy consumption and slurry preparation costs, while also prolonging the slurry preparation cycle. Low slurry preparation efficiency: Traditional slurry preparation equipment and processes are not very efficient for preparing low-concentration loess slurries. For example, when using ordinary mixers, because the loess content in low-concentration slurries is relatively low, "virtual mixing" easily occurs during the mixing process, failing to fully utilize the efficiency of the mixing equipment.

[0005] Severe grout loss: During grouting, low-concentration loess grout (loess grout concentration <40%) tends to rapidly penetrate soil pores due to its low viscosity, causing grout to be lost to non-target areas, especially in strata with larger porosity. This is because low-concentration grout has relatively poor impermeability. To address this issue, thickeners are often added to increase the grout viscosity; however, the type and amount of thickener require extensive testing to determine, and excessive addition may affect the later strength of the grout.

[0006] Grouting pressure control is challenging: the high fluidity of low-concentration yellow mud slurry makes accurate pressure control during grouting difficult. Excessive pressure can lead to ground fracturing, resulting in slurry waste and ground uplift; insufficient pressure, on the other hand, fails to ensure effective slurry diffusion within the formation. Due to the complex and variable geological conditions of different strata, establishing an accurate pressure control model is difficult, requiring continuous adjustments based on actual conditions during construction, increasing the difficulty and uncertainty of the project. Summary of the Invention

[0007] The present invention aims to at least partially solve one of the technical problems in the related art.

[0008] To address the problems of low material concentration, slow slurry setting speed, and single material ratio in current pulping processes, resulting in insufficient material setting strength after water evaporation and thus insufficient filling strength in goafs or coal mine fissures, posing a significant risk of secondary collapse and subsidence, this invention proposes a high-concentration gradation slurry preparation system and method for sandy loess.

[0009] In a first aspect, the present invention proposes a high-concentration gradation slurry preparation system for sandy loess, comprising: The primary inclined screen is used to remove frozen soil clods and stones from sandy loess. The secondary drum screen, located downstream of the primary inclined screen, is used to remove sand particles from the sandy loess so that the sand content in the sandy loess is below 10%. The material storage workshop is used to store the refined loess obtained after being screened by the secondary drum screen. A quantitative feeding bin is used to quantitatively transport the refined loess to the first pulping machine, in which the refined loess is mixed with water to obtain the first slurry; A second pulping machine is located downstream of the first pulping machine. In the second pulping machine, cement ash, additives and the first slurry are mixed to obtain a second slurry.

[0010] Furthermore, the aperture of the primary inclined screen is 50~100mm.

[0011] Furthermore, the aperture of the secondary drum screen is 5~10mm.

[0012] Furthermore, the quantitative feeding bin is equipped with crushing teeth.

[0013] Furthermore, a belt conveyor is provided between the quantitative feeding bin and the first pulping machine.

[0014] Furthermore, the mass concentration of loess in the first slurry is 50% to 60%.

[0015] Furthermore, the mass concentration of loess in the second slurry is 65%~80%.

[0016] Furthermore, the mass concentration of the additive is 0.5% to 1%.

[0017] Furthermore, the additive includes at least one of sodium dodecyl sulfate and polycarboxylate superplasticizer.

[0018] Secondly, this invention proposes a method for preparing high-concentration graded slurry from sandy loess, utilizing the high-concentration graded slurry preparation system for sandy loess proposed in the first aspect, comprising the following steps: The sandy loess was screened using a first-stage inclined screen and a second-stage drum screen to obtain refined loess, which was then stored in the material storage workshop. Refined loess is quantitatively fed to the first pulping machine via a belt conveyor using a quantitative feeding hopper and mixed with water to obtain the first slurry. The mass concentration of loess in the first slurry is 50%~60%. In the second pulping machine, the first slurry is mixed with cement ash and additives to obtain the second slurry, and the mass concentration of loess in the second slurry is 65%~80%.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention employs a tiered material screening process and a tiered material slurry mixing process to achieve high-concentration mixing and pulping of multi-component materials. By using more advanced pulping equipment and processes, it can make fuller use of loess and other additives, and produce a slurry volume that meets engineering requirements within a unit time. Compared with traditional low-concentration pulping processes, the pulping efficiency is higher.

[0020] The high-concentration loess slurry of this invention has a higher loess content, which, when combined with cement and other cementing materials, can form more cementing substances, thereby giving the slurry higher strength after solidification and better meeting the requirements of engineering for reinforcement and load-bearing capacity. The high-concentration slurry has more compact particles and lower porosity, which can effectively prevent the penetration of water and other fluids after being injected into the stratum, improving the waterproof performance of the project and giving it better impermeability. Attached Figure Description

[0021] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the high-concentration graded slurry preparation system for sandy loess of the present invention; Figure 2 This is a flowchart of the high-concentration gradation method for preparing slurry from sandy loess according to the present invention. Detailed Implementation

[0022] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0023] The following description, in conjunction with the accompanying drawings, describes the high-concentration gradation slurry preparation system and method for sandy loess proposed in this invention.

[0024] like Figure 1 As shown, the high-concentration gradation slurry preparation system for sandy loess of the present invention includes a primary inclined screen, a secondary drum screen, a material storage workshop, a quantitative feeding silo, a first slurry machine, and a second slurry machine arranged sequentially upstream and downstream.

[0025] This invention utilizes a primary inclined screen and a secondary drum screen to perform tiered screening of loess with a certain sand content. First, the primary inclined screen is used to preliminarily screen and remove large frozen soil lumps and large stones from the sandy loess. Then, the secondary drum screen is used to perform secondary fine screening of the sandy loess after the preliminary screening by the primary inclined screen, thereby controlling the sand content in the sandy loess to below 10%.

[0026] The primary inclined screen has an aperture of 50-100mm, which quickly removes frozen soil clods and stones, with a removal rate of over 98%. The secondary drum screen has an aperture of 5-10mm, which finely separates sand particles, ensuring that the sand content of the loess is below 10%.

[0027] In this invention, the sand content of the refined loess is below 10%, thereby preventing pipeline blockage during subsequent transportation, avoiding wear and tear on equipment pipelines, and extending the service life of the equipment.

[0028] The refined loess obtained after secondary drum screen screening is stored in the material storage workshop, where the moisture in the refined loess is volatilized as much as possible.

[0029] The quantitative feeding silo is located downstream of the material storage workshop. The refined loess from the material storage workshop is added to the quantitative feeding silo. The quantitative feeding silo is equipped with crushing teeth to enable it to crush the plate-like lumps of refined loess caused by accumulation before feeding it to the material.

[0030] Downstream of the quantitative feed silo is a variable frequency belt conveyor, and downstream of the variable frequency belt conveyor is a first pulping machine. The quantitative feed silo, via the variable frequency belt conveyor, uniformly and in large quantities, delivers refined loess to the first pulping machine. In the first pulping machine, the refined loess is mixed with water to obtain the first slurry, thus completing the first stage of high-concentration single-component material pulping. The mass concentration of the first slurry is 50%~60%.

[0031] The second pulping machine is located downstream of the first pulping machine. In the second pulping machine, cement ash, additives, and the first slurry are mixed to obtain the second slurry, thus completing the second stage of high-concentration material pulping. The second slurry contains 65%–80% loess by mass and 0.5%–1% additives by mass. The additives include at least one of sodium dodecyl sulfate and polycarboxylate superplasticizer. The additives adjust the surface potential of the cement and loess, achieving rapid particle dispersion, reducing particle agglomeration, releasing more free water, and shortening the stirring time during slurry preparation, thus enabling rapid slurry preparation.

[0032] It is understood that the system of the present invention also includes an intelligent control system, through which the amounts of refined loess, cement ash, water and additives are controlled and adjusted.

[0033] In this invention, the first and second pulping machines are designed in series, which realizes the sequential separation and mixing of loess slurry and cement, avoids premature setting, and achieves the preparation of high-concentration final slurry.

[0034] like Figure 2 As shown, the method for preparing high-concentration graded slurry from sandy loess, utilizing the system of this invention, includes the following steps: (1) The sandy loess was screened by a first-stage inclined screen and a second-stage drum screen in sequence to obtain refined loess, which was then stored in the material storage workshop. (2) The refined loess is quantitatively transported to the first pulping machine by a belt conveyor using a quantitative feeding bin and mixed with water to obtain the first slurry. The mass concentration of loess in the first slurry is 50%~60%. (3) In the second pulping machine, the first slurry is mixed with cement ash and additives to obtain the second slurry. The mass concentration of loess in the second slurry is 65%~80%.

[0035] Step (1) is a pretreatment process for refining loess. First, a primary inclined screen is used to pre-screen large frozen soil blocks and large stones in the sandy loess to remove them. Then, a secondary drum screen is used to pre-screen the sandy loess after the primary inclined screen to further refine the material and control the sand content in the sandy loess to below 10%.

[0036] In some embodiments, the primary inclined screen has a heating function, enabling it to process frozen soil at -20°C with an ice-breaking efficiency of over 95%, allowing the system to operate continuously even in winter. Approximately 30% of the high-sandy loess can be utilized at a rate of over 92% after secondary screening.

[0037] Step (2) is the preparation process of the first slurry. The fine loess is uniformly and in large quantities transported to the first pulping machine by a variable frequency belt conveyor through a quantitative feeding hopper. The fine loess is mixed with water in the first pulping machine to obtain the first slurry, thereby completing the first stage of high-concentration single-component material pulping. The mass concentration of loess in the first slurry is 50%~60%.

[0038] Step (3) is the preparation process of the second slurry. In the second slurry mixer, cement ash, additives and the first slurry are mixed to obtain the second slurry, thus completing the second stage of high-concentration material slurry preparation. Among them, the mass concentration of loess in the second slurry is 65%~80%, and the mass concentration of additives is 0.5%~1%.

[0039] The present invention will now be described in detail with reference to specific embodiments.

[0040] In a project to remediate the goaf of a small open-pit mine, cement and loess were used to prepare slurry and fill it to achieve the goal of goaf remediation.

[0041] First, a primary inclined sluice screen (60mm aperture) is used to preliminarily screen and remove large frozen soil clods and large stones from the sandy loess. Then, a secondary drum screen (10mm aperture) is used to further refine the sandy loess after the initial screening, thereby controlling the sand content in the loess to below 10%. The refined loess obtained after secondary drum screening is stored in a material storage workshop, where the moisture in the refined loess is volatilized as much as possible.

[0042] A quantitative feeding silo is used to uniformly and in large quantities transport refined loess to the first pulping machine via a variable frequency belt conveyor. In the first pulping machine, the refined loess is mixed with water to obtain the first slurry, thus completing the first stage of high-concentration single-component material pulping. The mass concentration of the first slurry is 50%.

[0043] The first slurry enters the second pulping machine, where cement ash, additives, and the first slurry are mixed to obtain the second slurry, thus completing the second stage of high-concentration material pulping. The second slurry contains 66% loess by mass.

[0044] According to the design, prepare a 1m 3 The required quantities of water, cement, loess, and sodium dodecyl sulfate for the slurry are 540 kg, 150 kg, 1344 kg, and 10 kg, respectively. Based on the properties of the sandy loess in Inner Mongolia, a tiered material screening process was used to prepare the slurry with a density of approximately 1.9 g / cm³. 3The high-concentration grout, after water separation, forms stones that account for more than 85% of the original grout volume. Under standard curing conditions, the uniaxial compressive strength of the test blocks after 28 days exceeds 0.6 MPa, which can meet the on-site filling strength requirements.

[0045] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms may refer to different embodiments or examples. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0046] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0047] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A high-concentration graded slurry preparation system for sandy loess, characterized in that, include: The primary inclined screen is used to remove frozen soil clods and stones from sandy loess. The secondary drum screen, located downstream of the primary inclined screen, is used to remove sand particles from the sandy loess so that the sand content in the sandy loess is below 10%. The material storage workshop is used to store the refined loess obtained after being screened by the secondary drum screen. A quantitative feeding bin is used to quantitatively transport the refined loess to the first pulping machine, in which the refined loess is mixed with water to obtain the first slurry; A second pulping machine is located downstream of the first pulping machine. In the second pulping machine, cement ash, additives and the first slurry are mixed to obtain a second slurry.

2. The high-concentration graded slurry preparation system for sandy loess as described in claim 1, characterized in that, The aperture of the primary inclined screen is 50~100mm.

3. The high-concentration graded slurry preparation system for sandy loess as described in claim 1, characterized in that, The aperture of the secondary drum screen is 5~10mm.

4. The high-concentration graded slurry preparation system for sandy loess as described in claim 1, characterized in that, The quantitative feeding hopper is equipped with crushing teeth.

5. The high-concentration graded slurry preparation system for sandy loess as described in claim 1, characterized in that, A belt conveyor is installed between the quantitative feeding bin and the first pulping machine.

6. The high-concentration graded slurry preparation system for sandy loess as described in claim 1, characterized in that, The mass concentration of loess in the first slurry is 50%~60%.

7. The high-concentration graded slurry preparation system for sandy loess as described in claim 1, characterized in that, The mass concentration of loess in the second slurry is 65%~80%.

8. The high-concentration graded slurry preparation system for sandy loess as described in claim 1, characterized in that, The mass concentration of the additive is 0.5% to 1%.

9. The high-concentration graded slurry preparation system for sandy loess as described in claim 8, characterized in that, The additives include at least one of sodium dodecyl sulfate and polycarboxylate superplasticizer.

10. A method for preparing high-concentration graded slurry from sandy loess, characterized in that, The high-concentration graded slurry preparation system for sandy loess as described in any one of claims 1 to 9 includes the following steps: The sandy loess was screened using a first-stage inclined screen and a second-stage drum screen to obtain refined loess, which was then stored in the material storage workshop. Refined loess is quantitatively fed to the first pulping machine via a belt conveyor using a quantitative feeding hopper and mixed with water to obtain the first slurry. The mass concentration of loess in the first slurry is 50%~60%. In the second pulping machine, the first slurry is mixed with cement ash and additives to obtain the second slurry, and the mass concentration of loess in the second slurry is 65%~80%.

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