A continuous mixing and pumping process for dry powder materials

Abstract

This invention relates to the field of dry powder material construction and discloses a continuous mixing and pumping process for dry powder materials, comprising: weighing dry powder raw materials according to a ratio, conveying them to a dry powder mixing tank for mixing to obtain a dry powder mixture; simultaneously conveying the dry powder mixture and water to a continuous mixing host with inclined mixing blades, controlling the feed and water ratio to maintain a set water-cement ratio, and obtaining a uniform slurry through continuous mixing; and continuously conveying the uniform slurry to a mud pump for pumping construction at a set pumping pressure and pumping rate. This invention, through independent dry powder pre-mixing and the strong shearing and mixing of the host, effectively eliminates powder agglomeration and unhydrated dry core, avoids slurry bleeding and segregation in pipelines, achieves continuous and stable pumping while ensuring homogeneous slurry preparation, reduces the risk of pipe blockage, and improves overall construction efficiency.

Description

Technical Field

[0001] This invention relates to the field of dry powder material construction, specifically a continuous mixing and pumping process for dry powder materials. Background Technology

[0002] Currently, dry powder materials are widely used in engineering fields such as mining, tunnel support, and building filling. The preparation and pipeline transportation of these dry powder-based materials are core aspects of the construction process. Reliable material mixing and smooth transportation directly affect the mechanical strength and operational safety of the final structure.

[0003] In conventional dry powder material slurry preparation processes, construction companies often employ a batch-by-batch, intermittent processing method. Operators simultaneously add various solid dry powders, such as cement and fly ash, into a single mixing chamber according to a pre-set ratio. The equipment is then directly injected with water and a single mixing cycle is initiated. After this batch of mechanical mixing is completed, the slurry in the chamber is unloaded and discharged into a lower transfer silo for storage. Finally, an external mud pump extracts the fluid from the silo and pressurizes it before pumping it to the target work area.

[0004] In conventional processes, powders and water are often directly mixed. The surface wettability of various dry powders varies significantly. Mineral powder and fly ash readily adhere to each other upon contact with water, quickly becoming enveloped by the liquid phase and forming a dense shell. Air inside the powder cannot escape, resulting in a large amount of residual microscopic dry core. Traditional single-stage mixing is insufficient to completely break down these suspended agglomerates using shear force; operators arbitrarily add water to adjust consistency based on experience, further disrupting the water-cement ratio balance of the system. This imbalance in internal moisture distribution leads to rapid bleeding and particle segregation in the slurry. The batch discharge method causes the fluid in the pipeline to exhibit an intermittent, pulsating state. Once segregation occurs, coarse particles quickly detach from the suspended phase and settle and accumulate at pipe bends. Pipeline frictional resistance spikes dramatically, ultimately leading to pipe blockage; frequent shutdowns for dredging completely disrupt the continuity of construction.

[0005] Therefore, the present invention provides a continuous stirring and pumping process for dry powder materials to overcome the shortcomings of the prior art. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a continuous stirring and pumping process for dry powder materials, which solves the problems of localized powder agglomeration forming a dry core, uneven mixing of water and powder, and large fluctuations in water-cement ratio control during the pulping and long-distance transportation of existing dry powder materials, which in turn cause slurry bleeding and segregation or pipeline blockage.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A continuous mixing and pumping process for dry powder materials includes the following steps: Weigh the dry powder raw materials according to the proportion, and transport the dry powder raw materials to the dry powder mixing tank for dry powder mixing to obtain a dry powder mixture. The dry powder mixture and water are simultaneously transported to a continuous mixing host with inclined mixing blades. The feed and water ratio is controlled to maintain the set water-cement ratio. After continuous mixing, a uniform slurry is obtained. The uniform slurry is continuously transported to the mud pump and pumped under the set pumping pressure and pumping rate.

[0008] By adopting the above technical solution, due to the pre-dry powder mixing step, the use of a continuous mixing host and inclined mixing blades for secondary homogenization, and the synchronous control of the feed and water ratio, the effects of eliminating powder core dryness, improving slurry uniformity, and achieving continuous and stable pipeline flow are achieved. The mixing principle and microscopic change mechanism of the process include the following steps: The first step is to homogenize and deagglomerate dry phase materials: the powder materials are mechanically agitated and sheared in the dry powder mixing tank, breaking the initial aggregation state between fine fly ash, mineral powder and other particles caused by van der Waals forces and electrostatic effects, so that the various components are evenly dispersed at the microscale.

[0009] The second step is the forced removal of the hydration coating: the homogenized dry powder mixture enters the continuous mixing host, and the high-speed rotating inclined mixing blades generate strong radial shear force and axial thrust inside the cylinder, forcibly removing the air coating layer on the outside of the solid particles, so that the liquid phase water molecules can quickly wet the surface of the solid powder.

[0010] The third step is the construction of the suspended floc network: Under the control of a stable water-cement ratio, the solid surface material begins to dissolve and enter the liquid phase. The particles are connected by attraction and initial hydration products, and are reshaped and dispersed in a strong shear flow field to form a uniformly distributed flocculent network structure without large-sized agglomerates.

[0011] Preferably, before conveying the dry powder raw materials to the dry powder mixing tank, each dry powder raw material is pretreated by a vibrating screen, and the pretreated raw materials are conveyed to the dry powder mixing tank by a screw conveyor.

[0012] By adopting the above technical solutions, the vibrating screen removes large-sized foreign objects and damp, agglomerated particles from the raw materials, and the screw conveyor provides a continuous and stable feeding speed, maintaining the continuity of the dry powder mixing process.

[0013] Preferably, the mixing time for the dry powder is 4 to 6 minutes.

[0014] By adopting the above technical solution, the limited dry powder mixing time ensures that various materials can reach a macroscopic physical uniform state, avoids local component enrichment caused by insufficient mixing time, and prevents secondary electrostatic agglomeration of powder or stratification of particles with different specific gravities caused by excessive mixing for a long time.

[0015] Preferably, water enters the continuous mixing host through a high-pressure water pipe connected to a water source, and the water pressure is stably controlled at 0.7 to 0.9 MPa; an electromagnetic flow valve and a pressure regulating valve are installed on the high-pressure water pipe.

[0016] By adopting the above technical solution, the stable high water pressure gives the water flow initial kinetic energy, making it easy to penetrate into the dry powder material flow inside the main unit. The electromagnetic flow valve combined with the pressure regulating valve forms a real-time control of the flow rate in the water inlet pipeline, providing a material basis for the subsequent constant water-cement ratio.

[0017] Preferably, 6 to 8 sets of stirring blades are evenly distributed on the stirring shaft inside the continuous stirring host, and the inclination angle of the stirring blades is 30 to 45°; the stirring speed of the continuous stirring host is controlled at 180 to 240 r / min.

[0018] By adopting the above technical solution, the set blade arrangement and tilt angle change the single flow trajectory of the material inside the host, causing the material to backflow and turn back during the forward process. The set stirring speed provides sufficient mechanical shear energy for the forced mixing of powder and water, and completely breaks up the powder clumps wrapped by the liquid bridge.

[0019] Preferably, when the dry powder mixture is conveyed to the continuous mixing host, the feeding speed is controlled at 180-220 kg / min; the water-cement ratio is controlled at 0.45-0.52 based on the ratio of the total mass of the dry powder mixture to the mass of the water, and the error of the water-cement ratio is less than or equal to ±0.02.

[0020] By adopting the above technical solution, the powder feeding speed is set in a suitable range to match the volume processing capacity of the host, and the water-cement ratio and its error range are strictly defined, ensuring that the ratio of free water to bound water inside the generated slurry is in a balanced state, so that the fluid has suitable plastic viscosity and yield stress.

[0021] Preferably, the mud pump is a horizontal single screw pump, and during the pumping construction process, the pumping rate is controlled at 100-260 L / min and the pumping pressure is 1.2-1.8 MPa.

[0022] By adopting the above technical solution, the stator and rotor structure of the horizontal single screw pump realizes volumetric pulse-free output. The set pumping rate and pressure parameters enable the suspended slurry to maintain a stable laminar flow state in the conveying pipeline, avoiding phase separation caused by turbulence.

[0023] Preferably, the dry powder raw material is composed of the following components in total, which are 100% by mass percentage: 40-50% cement, 10% mineral powder, 10-15% fly ash, 20-25% gypsum adhesive powder, and 10% red mud powder.

[0024] By adopting the above technical solutions, cement provides the basic cementitious strength in the formulation system, mineral powder and fly ash fill the particle pores and undergo pozzolanic reaction through morphological effects, gypsum powder regulates the hydration process of the system, and red mud powder provides a strong alkaline activation environment. The components work together to form a cementitious material structure with good fluidity retention and stable volume after hardening.

[0025] Preferably, the specific surface area of ​​the red mud powder is 350-400 m² / kg; the moisture content of each component in the dry powder raw material is ≤0.5%.

[0026] By adopting the above technical solutions, controlling the specific surface area of ​​red mud powder ensures that its surface has a sufficient proportion of active sites for alkali-activated reactions, and limiting the upper limit of the moisture content of each material cuts off the source of moisture for early hydration in the dry powder mixing stage, thus maintaining the fluidity of the dry powder raw materials.

[0027] Preferably, the top of the continuous mixing host is provided with a powder inlet and a water inlet, and the dry powder mixture is transported to the powder inlet through a closed pipeline.

[0028] By adopting the above technical solution, the sealed pipeline isolates the contact path between the powder material and the external environment moisture, and the top-mounted feeding structure allows the powder to fall vertically into the center of the mixing area under the action of gravity, reducing the probability of dust being scattered and spilled outward.

[0029] This invention provides a continuous stirring and pumping process for dry powder materials. It offers the following advantages: 1. This invention establishes a separate dry powder pre-mixing step before adding water to homogenize dry powder raw materials with different specific gravities and particle sizes. This step dissolves the initial aggregation between powder particles, avoiding local agglomeration caused by differences in surface wettability when multiple powders come into direct contact with water. This provides a stable solid material basis for the subsequent rapid and continuous slurry preparation process, reduces downtime caused by material inhomogeneity, and ensures construction efficiency.

[0030] 2. This invention employs inclined mixing blades within the continuous mixing unit, combined with synchronized adjustment of inlet water pressure and feed rate to strictly control the water-cement ratio. The radial shear and axial thrust generated during the operation of the inclined blades forcefully break up the initial clumps formed upon contact with water, eliminating unhydrated dry cores within the slurry. This achieves rapid mixing while preventing slurry bleeding and segregation, ensuring the quality stability of continuous discharge.

[0031] 3. This invention utilizes a multi-component synergistic dry powder raw material formulation to construct a suspension slurry with suitable viscosity, and combines this with the constant volume and pulse-free output characteristics of a horizontal single-screw pump for delivery. The slurry maintains a laminar flow state under stable pumping pressure, effectively reducing the risk of pipeline blockage during long-distance continuous construction. This not only ensures the continuity of the pumping process but also reduces the frequency of manual pipeline dredging and cleaning, thereby reducing labor intensity and equipment maintenance costs. Attached Figure Description

[0032] Figure 1 This is a slurry flowability diagram of an embodiment of the present invention; Figure 2 This is a standard 3D intensity diagram of an embodiment of the present invention. Figure 3 This is a 7-day intensity diagram under standard maintenance according to an embodiment of the present invention; Figure 4 This is a standard 28-day curing intensity diagram for an embodiment of the present invention. Detailed Implementation

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0035] The ordinary Portland cement used in the embodiments and comparative examples of this invention is commercially available P.O42.5 grade ordinary Portland cement (CAS No. 65997-15-1), the mineral powder is commercially available S95 grade granulated blast furnace slag powder (CAS No. 65996-69-2), the fly ash is commercially available Grade I fly ash (CAS No. 68131-74-8), the gypsum adhesive powder is commercially available α-hemihydrate gypsum adhesive powder (CAS No. 10034-76-1), and the red mud powder is commercially available with a specific surface area of ​​350 to 400 m². 2 / kg of red mud powder, the moisture content of each of the above raw materials is less than or equal to 0.5%.

[0036] Examples 1-5: Example 1: This embodiment provides a continuous stirring and pumping process for dry powder materials, including the following steps: Weigh out cement, mineral powder, fly ash, gypsum adhesive powder, and red mud powder according to the following proportions: cement 40%, mineral powder 10%, fly ash 15%, gypsum adhesive powder 25%, and red mud powder 10%.

[0037] Each raw material is pre-treated by passing it through a vibrating screen. The dry powder mixing device is turned on, and the components in the raw material silo are transported to the dry powder mixing tank by a screw conveyor according to the above proportions. The dry powder mixing time is 4 to 6 minutes, so that the uniformity of the dry powder mixture reaches more than 98% and there is no obvious particle agglomeration.

[0038] The pre-mixed dry powder mixture is transported to the continuous mixing host through a closed pipeline. The top of the continuous mixing host is equipped with a powder inlet and a water inlet. The water inlet is connected to a water source through a high-pressure water pipe, and the water pressure is stably controlled at 0.7 to 0.9 MPa. The water pipe is equipped with an electromagnetic flow valve and a pressure regulating valve to adjust the water inlet in real time. There are 6 to 8 sets of mixing blades evenly distributed on the mixing shaft inside the continuous mixing host. The blades have an inclined structure with an inclination angle of 30 to 45°. The water-cement ratio is controlled at 0.45 through the powder inlet and the water inlet. The water-cement ratio is calculated as the ratio of the total mass of the dry powder mixture to the mass of the water, with an error of less than or equal to ±0.02. The feeding speed is controlled at 180 to 220 kg / min. The water and dry powder are mixed into a uniform slurry, and the mixing speed is controlled at 200 to 220 r / min.

[0039] After mixing, the slurry is transported to the feed inlet of the mud pump through the discharge port. The mud pump is a horizontal single screw pump, and the pumping rate is controlled between 100 and 260 L / min, and the pumping pressure is between 1.2 and 1.8 MPa.

[0040] Example 2: This embodiment provides a continuous stirring and pumping process for dry powder materials, including the following steps: Weigh out cement, mineral powder, fly ash, gypsum adhesive powder, and red mud powder according to the following proportions: cement 40%, mineral powder 10%, fly ash 15%, gypsum adhesive powder 25%, and red mud powder 10%.

[0041] Each raw material is pre-treated by passing it through a vibrating screen. The dry powder mixing device is turned on, and the components in the raw material silo are transported to the dry powder mixing tank by a screw conveyor according to the above proportions. The dry powder mixing time is 4 to 6 minutes, so that the uniformity of the dry powder mixture reaches more than 98% and there is no obvious particle agglomeration.

[0042] The pre-mixed dry powder mixture is transported to the continuous mixing host through a closed pipeline. The top of the continuous mixing host is equipped with a powder inlet and a water inlet. The water inlet is connected to a water source through a high-pressure water pipe, and the water pressure is stably controlled at 0.7 to 0.9 MPa. The water pipe is equipped with an electromagnetic flow valve and a pressure regulating valve to adjust the water inlet in real time. There are 6 to 8 sets of mixing blades evenly distributed on the mixing shaft inside the continuous mixing host. The blades have an inclined structure with an inclination angle of 30 to 45°. The water-cement ratio is controlled at 0.48 through the powder inlet and water inlet. The water-cement ratio is calculated as the ratio of the total mass of the dry powder mixture to the mass of the water, with an error of less than or equal to ±0.02. The feeding speed is controlled at 180 to 220 kg / min. The water and dry powder are mixed into a uniform slurry, and the mixing speed is controlled at 200 to 220 r / min.

[0043] After mixing, the slurry is transported to the feed inlet of the mud pump through the discharge port. The mud pump is a horizontal single screw pump, and the pumping rate is controlled between 100 and 260 L / min, and the pumping pressure is between 1.2 and 1.8 MPa.

[0044] Example 3: This embodiment provides a continuous stirring and pumping process for dry powder materials, including the following steps: Weigh out cement, mineral powder, fly ash, gypsum adhesive powder, and red mud powder according to the following proportions: cement 40%, mineral powder 10%, fly ash 15%, gypsum adhesive powder 25%, and red mud powder 10%.

[0045] Each raw material is pre-treated by passing it through a vibrating screen. The dry powder mixing device is turned on, and the components in the raw material silo are transported to the dry powder mixing tank by a screw conveyor according to the above proportions. The dry powder mixing time is 4 to 6 minutes, so that the uniformity of the dry powder mixture reaches more than 98% and there is no obvious particle agglomeration.

[0046] The pre-mixed dry powder mixture is transported to the continuous mixing host through a closed pipeline. The top of the continuous mixing host is equipped with a powder inlet and a water inlet. The water inlet is connected to a water source through a high-pressure water pipe, and the water pressure is stably controlled at 0.7 to 0.9 MPa. The water pipe is equipped with an electromagnetic flow valve and a pressure regulating valve to adjust the water inlet in real time. There are 6 to 8 sets of mixing blades evenly distributed on the mixing shaft inside the continuous mixing host. The blades have an inclined structure with an inclination angle of 30 to 45°. The water-cement ratio is controlled at 0.52 through the powder inlet and water inlet. The water-cement ratio is calculated as the ratio of the total mass of the dry powder mixture to the mass of the water, with an error of less than or equal to ±0.02. The feeding speed is controlled at 180 to 220 kg / min. The water and dry powder are mixed into a uniform slurry, and the mixing speed is controlled at 200 to 220 r / min.

[0047] After mixing, the slurry is transported to the feed inlet of the mud pump through the discharge port. The mud pump is a horizontal single screw pump, and the pumping rate is controlled between 100 and 260 L / min, and the pumping pressure is between 1.2 and 1.8 MPa.

[0048] Example 4: This embodiment provides a continuous stirring and pumping process for dry powder materials, including the following steps: Weigh out cement, mineral powder, fly ash, gypsum adhesive powder, and red mud powder according to the following proportions: cement 50%, mineral powder 10%, fly ash 10%, gypsum adhesive powder 20%, and red mud powder 10%.

[0049] Each raw material is pre-treated by passing it through a vibrating screen. The dry powder mixing device is turned on, and the components in the raw material silo are transported to the dry powder mixing tank by a screw conveyor according to the above proportions. The dry powder mixing time is 4 to 6 minutes, so that the uniformity of the dry powder mixture reaches more than 98% and there is no obvious particle agglomeration.

[0050] The pre-mixed dry powder mixture is transported to the continuous mixing host through a closed pipeline. The top of the continuous mixing host is equipped with a powder inlet and a water inlet. The water inlet is connected to a water source through a high-pressure water pipe, and the water pressure is stably controlled at 0.7 to 0.9 MPa. The water pipe is equipped with an electromagnetic flow valve and a pressure regulating valve to adjust the water inlet in real time. There are 6 to 8 sets of mixing blades evenly distributed on the mixing shaft inside the continuous mixing host. The blades have an inclined structure with an inclination angle of 30 to 45°. The water-cement ratio is controlled at 0.48 through the powder inlet and water inlet. The water-cement ratio is calculated as the ratio of the total mass of the dry powder mixture to the mass of the water, with an error of less than or equal to ±0.02. The feeding speed is controlled at 180 to 220 kg / min. The water and dry powder are mixed into a uniform slurry, and the mixing speed is controlled at 180 to 190 r / min.

[0051] After mixing, the slurry is transported to the feed inlet of the mud pump through the discharge port. The mud pump is a horizontal single screw pump, and the pumping rate is controlled between 100 and 260 L / min, and the pumping pressure is between 1.2 and 1.8 MPa.

[0052] Example 5: This embodiment provides a continuous stirring and pumping process for dry powder materials, including the following steps: Weigh out cement, mineral powder, fly ash, gypsum adhesive powder, and red mud powder according to the following proportions: cement 40%, mineral powder 10%, fly ash 15%, gypsum adhesive powder 25%, and red mud powder 10%.

[0053] Each raw material is pre-treated by passing it through a vibrating screen. The dry powder mixing device is turned on, and the components in the raw material silo are transported to the dry powder mixing tank by a screw conveyor according to the above proportions. The dry powder mixing time is 4 to 6 minutes, so that the uniformity of the dry powder mixture reaches more than 95% and there is no obvious particle agglomeration.

[0054] The pre-mixed dry powder mixture is transported to the continuous mixing host through a closed pipeline. The top of the continuous mixing host is equipped with a powder inlet and a water inlet. The water inlet is connected to a water source through a high-pressure water pipe, and the water pressure is stably controlled at 0.7 to 0.9 MPa. The water pipe is equipped with an electromagnetic flow valve and a pressure regulating valve to adjust the water inlet in real time. There are 6 to 8 sets of mixing blades evenly distributed on the mixing shaft inside the continuous mixing host. The blades have an inclined structure with an inclination angle of 30 to 45°. The water-cement ratio is controlled at 0.48 through the powder inlet and water inlet. The water-cement ratio is calculated as the ratio of the total mass of the dry powder mixture to the mass of the water, with an error of less than or equal to ±0.02. The feeding speed is controlled at 180 to 220 kg / min. The water and dry powder are mixed into a uniform slurry, and the mixing speed is controlled at 230 to 240 r / min.

[0055] After mixing, the slurry is transported to the feed inlet of the mud pump through the discharge port. The mud pump is a horizontal single screw pump, and the pumping rate is controlled between 100 and 260 L / min, and the pumping pressure is between 1.2 and 1.8 MPa.

[0056] Comparative Examples 1-5: Comparative Example 1: Compared with Example 2, the difference is that instead of using a continuous mixing host and dual feed inlets, a traditional single mixer is used. The same proportion of raw materials and water are put into the mixer at once and mixed for 5 minutes, then discharged into the silo and pumped. Everything else is the same.

[0057] Comparative Example 2: Compared with Example 2, the difference is that the dry powder premixing step is cancelled, and the five raw material powders are directly added to the continuous mixing host and mixed with water. All other aspects are the same.

[0058] Comparative Example 3: Compared with Example 2, the difference is that the stirring blades of the continuous stirring host are replaced with ordinary straight blades, that is, the tilt angle is 0°, and everything else is the same.

[0059] Comparative Example 4: Compared with Example 2, the difference is that the water-cement ratio is adjusted to 0.60, which is outside the range of 0.45-0.52, but the rest are the same.

[0060] Comparative Example 5: Compared with Example 2, the difference is that red mud powder and gypsum adhesive powder are not added to the formula, but are replaced with an equal amount of fly ash, that is, the proportion of fly ash is 50%, and the rest are the same.

[0061] Test Example 1-3: Test Example 1: Experimental steps: A simulated engineering filling pipeline system was constructed, consisting of a standard-diameter rigid conveying pipe with a total length of 80 meters, connected to the discharge port of the mud pump. A high-frequency pressure sensor with a range of 0-5 MPa was installed at the mud pump outlet, and the device was connected to a data acquisition terminal with a sampling frequency set to 1 Hz to continuously record changes in pumping pressure.

[0062] Start the continuous mixing and pumping systems corresponding to Examples 1 to 5, and set the single uninterrupted operation time to 4 hours. No manual intervention is performed during the test. Record the overall operation of the system and count the number of shutdowns and flow interruptions caused by unstable material flow, pipeline pressure buildup, or equipment overload.

[0063] Slurry sampling was conducted during system operation. Freshly mixed slurry was collected at the outlet at the end of the pipeline every hour of operation, with a sample size of 2000g each time. The sampled slurry was placed on a standard square-hole sieve with a aperture of 1.18mm, and low-pressure water was turned on for washing and sieving until clear water flowed out from the bottom of the sieve.

[0064] Collect the remaining undispersed dry powder agglomerates on the sieve and transfer them to an electrically heated drying oven. Dry them at 105°C to constant weight and weigh them using a high-precision balance. Calculate the total mass of the dry powder based on the solid content of the sampled slurry, and determine the percentage of undispersed particles in the total solid powder mass.

[0065] Extract the 4-hour pumping pressure data recorded by the acquisition terminal, extract the data segment of the steady-state operation phase of the system, and calculate the average pumping pressure and pressure fluctuation range of each embodiment.

[0066] Experimental data: Table 1. Results of stability and macroscopic condition tests during continuous construction operations in Examples 1-5 in conclusion: According to the data in Table 1, no flow interruption or shutdown occurred during the 4-hour continuous load test in Examples 1 to 5, proving that the dual-inlet structure and water pressure stabilization control mechanism in the process flow of this invention are well-matched, maintaining material inflow and outflow balance and achieving uninterrupted pumping operation. The proportion of undispersed particles was between 0.82% and 1.42%, indicating that there were almost no obvious powder agglomerates in the discharged slurry. After the dry powder underwent pre-mixing treatment by the screw conveyor and dry powder mixing tank, it initially achieved a physical uniformity of over 95%, avoiding localized encapsulation caused by sedimentation differences when fly ash, mineral powder, and cement of different densities directly contacted water. After the material entered the main unit, the stirring blades with an inclination angle of 30 to 45° applied bidirectional shearing force in the axial and radial directions at a speed of 180 to 240 r / min, peeling off the hydration coating layer on the surface of the powder particles and causing the small amount of micro-agglomerates to disintegrate rapidly.

[0067] The average pumping pressure data ranged from 1.38 MPa to 1.63 MPa, with no overpressure exceeding 1.8 MPa, and the pressure fluctuation range throughout the entire operating cycle was controlled within 0.08 MPa to 0.19 MPa. The stable output of pipeline pressure confirmed the homogeneity of the slurry's macroscopic state. Due to the absence of undispersed hard particles within the slurry, the internal frictional resistance during shear flow within the pipeline remained constant, preventing an increase in pipe wall friction caused by sudden changes in local solid concentration. The uniform rheological state ensured that the output power of the horizontal single-screw pump was smoothly transmitted to the fluid, eliminating the risks of pipeline pressure buildup and pump overload, and providing a continuous and stable pumping environment.

[0068] Test Example 2: Experimental steps: During the stable operation phase of each set of process equipment, prepare a standard truncated cone mold with an inner diameter of 36mm, an outer diameter of 60mm, and a height of 60mm, as well as a flat glass plate and a ruler. Before testing, place the glass plate horizontally and wipe the surface of the glass plate and the inner wall of the truncated cone mold with a damp towel to keep them moist but without standing water.

[0069] Place the truncated cone mold at the center of the glass plate. At the discharge port of the continuous mixer, use a sampling container to collect approximately 3000g of the freshly discharged homogeneous slurry.

[0070] Quickly pour the cut slurry into the truncated cone mold until the slurry surface is slightly higher than the top edge of the mold. Use a scraper to scrape off the excess slurry, keeping the top surface of the slurry inside the mold flush with the mold surface.

[0071] Lift the truncated cone mold vertically and at a constant speed, avoiding lateral disturbance to the slurry at the bottom during the lifting process, so that the slurry inside can flow and spread freely on the glass plate under the action of gravity.

[0072] After the slurry has completely stopped flowing, use a ruler to measure the maximum diameter of the slurry spreading area, and also measure the diameter in the direction perpendicular to this maximum diameter. Calculate the arithmetic mean of these two diameters and use it as the initial flowability data for this group of slurries, in mm. Repeat the sampling and testing three times for each example and comparative example, and record the average value.

[0073] Experimental data: Table 2. Initial Flowability Test Results of Slurries in Examples and Comparative Examples Note: "-" indicates that valid flowability data could not be measured.

[0074] in conclusion: according to Figure 1 According to the data in Table 2, the slurry flowability of Example 1 was 189 mm, that of Example 2 was 198 mm, that of Example 3 was 231 mm, that of Example 4 was 222 mm, and that of Example 5 was 210 mm. Comparison within the examples shows that within the water-cement ratio control range of 0.45 to 0.52, as the water content increases, the amount of free water inside the fluid increases, the thickness of the water film on the particle surface increases, and the yield stress and plastic viscosity of the slurry system decrease accordingly. Example 3 exhibited the highest flowability, demonstrating the optimal flow state within this water-cement ratio range. This proves that real-time water volume control by the continuous mixing unit can stably maintain the macroscopic working performance of the fluid, meeting the rheological requirements of long-distance pumping.

[0075] Meanwhile, the comparative test results indirectly verified the necessity of the key steps in this process. Comparative Example 1 used an intermittent single-unit mixer for mixing, and under the same water-cement ratio, the measured flowability was only 165 mm, indicating an overall dry state. This is because the low-speed, straight shearing of a single unit cannot effectively remove adsorbed air from the particle surface, causing moisture to be trapped inside the agglomerates, reducing the effective free water content in the system. In Comparative Example 2, after omitting the dry powder premixing step, the measured flowability dropped to 142 mm, and obvious particle agglomeration was observed at the edges of the slurry. This is due to the significant differences in water absorption rates among various solid waste sources, especially those with a specific surface area of ​​350-400 m². 2 When red mud powder (at a concentration of / kg) is added directly to water without premixing, fine particles rapidly encapsulate coarse particles, forming agglomerates that hinder hydration and cause a sharp drop in flowability. In Comparative Example 4, the water-cement ratio was relaxed to 0.60. During testing, the slurry dispersed rapidly, but after settling, severe segregation and bleeding occurred, with coarse particles settling quickly. This unstable slurry, once entering the pipeline, easily causes a pressure filtration effect, ultimately leading to pipe blockage. The comparative results clearly demonstrate the irreplaceable role of this invention—through dry powder pretreatment homogenization, simultaneous feeding from dual inlets, and precise control of the water-cement ratio from 0.45 to 0.52—in establishing a uniform and stable suspended slurry system and ensuring excellent pumping performance.

[0076] Test Example 3: Experimental steps: Prepare a standard triple mold and evenly apply release agent to its inner wall. Once the continuous mixing unit and mud pump are running stably, use a sampling container to collect slurry at the discharge port.

[0077] The obtained slurry was poured into the mold in two batches. After each batch was filled, the mold was placed on a vibrating table and vibrated to compact it until the surface was covered with slurry and no air bubbles overflowed. Vibration was stopped, and excess slurry was scraped off with a scraper close to the top edge of the mold.

[0078] The molded specimens were transferred into a standard constant temperature and humidity curing chamber, with the temperature controlled at 20±2℃ and the relative humidity greater than 95%. After curing in the mold for 24 hours, the specimens were demolded and numbered.

[0079] After demolding, the specimens were placed in a standard curing chamber and cured for 3 days, 7 days and 28 days respectively.

[0080] After reaching the specified age, the specimens were removed and placed in the center of the bearing plate of a computer-controlled constant-pressure universal testing machine. A loading rate of 0.5 MPa / s was set and continuously applied until the specimen failed, recording the maximum load. The unconfined compressive strength of each specimen was calculated, and the arithmetic mean of the three specimens tested in each group was taken as the strength data for that age.

[0081] Experimental data: Table 3. Results of unconfined compressive strength tests at different ages in conclusion: According to Table 3 and Figure 2 , Figure 3 , Figure 4 The data show that the compressive strengths of Examples 1, 2, 3, 4, and 5 after 3 days of standard curing were 16.5 MPa, 9.2 MPa, 6.1 MPa, 12.8 MPa, and 11.3 MPa, respectively; after 7 days of standard curing, they were 21.4 MPa, 13.2 MPa, 11.9 MPa, 18.1 MPa, and 15.4 MPa, respectively; and after 28 days of standard curing, they were 44.8 MPa, 28.5 MPa, 24.1 MPa, 36.5 MPa, and 33.7 MPa, respectively. The strength performance of the Example groups at all ages was higher than that of the comparative group.

[0082] In the early strength development stage, the 3-day compressive strength of Comparative Example 1 and Comparative Example 2 were 5.1 MPa and 4.3 MPa, respectively, significantly lower than that of the Example system. The Example process introduced a screw conveyor and dry powder mixing step before the material entered the water, achieving a powder uniformity of over 98%. Combined with the high-speed shearing of the 30-45° inclined blades inside the continuous motor, the air barrier layer on the surface of the fine powder was broken down. The cementitious material could fully initiate the hydration reaction in the initial stage of contact with water, generating early hydration products such as hydrated calcium silicate and ettringite. The traditional intermittent mixing in Comparative Example 1 and the elimination of premixing in Comparative Example 2 resulted in localized water absorption and encapsulation of the fine particles upon entering the water. Unreacted dry powder formed agglomerated cores, hindering the hydration process and leading to lower compressive strength in the early stages of matrix solidification.

[0083] During the mid-term strength development process, the water-cement ratio plays a decisive role in the internal density and mechanical load-bearing capacity of the material. In Comparative Example 4, due to the relaxed water-cement ratio to 0.60, its 7-day compressive strength was only 5.8 MPa. Excessive free water, after early curing and evaporation, left numerous interconnected capillaries and seepage channels within the matrix, resulting in a loose microstructure. Examples 1 to 5 limited the water-cement ratio to the range of 0.45 to 0.52, reducing the initial porosity of the cured body while ensuring the pumpability of the slurry. The generated hydration products effectively filled the limited capillaries within the matrix, promoting a stable improvement in the mechanical properties of the example group at 7 days.

[0084] Regarding long-term mechanical properties, the test data reflect the chemical synergistic effect of the multi-component solid waste material system and the dispersion effect of the mixing equipment. Comparative Example 5, lacking red mud powder and gypsum powder, achieved a final 28-day strength of 14.2 MPa. In the example system, the red mud powder released strongly alkaline substances during the later stages of hydration, promoting the deagglomeration of the glassy network on the surface of fly ash and slag powder, accelerating the dissolution of active silica-alumina components; the sulfate ions provided by the gypsum powder participated in subsequent hydration, generating a large number of needle-like ettringite crystals. This resulted in the ettringite crystals and CSH gel interweaving and constructing a high-density spatial network structure, enabling Example 1 to achieve a 28-day strength of 44.8 MPa. Comparative Example 3, using ordinary straight stirring blades, achieved a 28-day strength of 21.3 MPa. The shear stress distribution generated by the straight blades was singular, failing to completely disperse the tiny powder agglomerates, resulting in areas of uneven component distribution within the solidified matrix. These incompletely dispersed interfaces are prone to stress concentration when the specimen is under pressure, leading to the formation and gradual propagation of microcracks, which limit the increase in the material's final load-bearing capacity. This process improves the overall strength properties of the filling material by combining physical premixed shearing with chemical synergistic activation.

Claims

1. A continuous mixing and pumping process of dry powder material, characterized in that, Includes the following steps: Weigh the dry powder raw materials according to the proportion, and transfer the dry powder raw materials to the dry powder mixing tank for dry powder mixing to obtain a dry powder mixture. The dry powder mixture and water are simultaneously fed into a continuous mixing host with inclined mixing blades. The ratio of feed to water is controlled to maintain the set water-cement ratio. A uniform slurry is obtained through continuous mixing. The uniform slurry is continuously transported to a mud pump, and pumping is carried out under the set pumping pressure and pumping rate.

2. Continuous mixing and pumping process according to claim 1, characterized in that, Before the dry powder raw materials are conveyed to the dry powder mixing tank, each of the dry powder raw materials is pretreated by a vibrating screen. The pretreated raw materials are then conveyed to the dry powder mixing tank by a screw conveyor.

3. Continuous mixing and pumping process according to claim 1, characterized in that, The dry powder is stirred for 4 to 6 minutes.

4. The continuous mixing and pumping process of claim 1, wherein, Water enters the continuous mixing host through a high-pressure water pipe connected to a water source, and the water pressure is stably controlled at 0.7-0.9 MPa; the high-pressure water pipe is equipped with an electromagnetic flow valve and a pressure regulating valve.

5. The continuous mixing and pumping process of claim 1, wherein, The stirring shaft inside the continuous stirring host has 6 to 8 sets of stirring blades evenly distributed, the inclination angle of the stirring blades is 30 to 45°, and the stirring speed of the continuous stirring host is controlled at 180 to 240 r / min.

6. The continuous mixing and pumping process of claim 1, wherein, When conveying the dry powder mixture to the continuous mixing host, the feeding speed is controlled at 180-220 kg / min; The water-cement ratio is calculated based on the ratio of the total mass of the dry powder mixture to the mass of the incoming water. The water-cement ratio is controlled between 0.45 and 0.52, and the error of the water-cement ratio is less than or equal to ±0.

02.

7. The continuous mixing and pumping process of claim 1, wherein, The mud pump is a horizontal single screw pump. During the pumping operation, the pumping rate is controlled at 100-260 L / min and the pumping pressure is 1.2-1.8 MPa.

8. The continuous mixing and pumping process of claim 1, wherein, The dry powder raw material is composed of the following components, which together make up 100% by weight: Cement 40-50%, mineral powder 10%, fly ash 10-15%, gypsum adhesive powder 20-25%, red mud powder 10%.

9. Continuous mixing and pumping process according to claim 8, characterized in that, The specific surface area of the red mud powder is 350-400 m 2 / kg, the moisture content of each component in the dry powder raw material is ≤0.5%.

10. The continuous stirring and pumping process according to claim 1, characterized in that, The top of the continuous mixing host is provided with a powder inlet and a water inlet, and the dry powder mixture is transported to the powder inlet through a closed pipeline.

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