Vortex ring mixed red mud settling separation washing device and application system and method

Abstract

The invention discloses a vortex ring mixed red mud settling separation washing device and an application system and method.The vortex ring mixed red mud settling separation washing device comprises a material mixing chute, the material mixing chute comprises a material mixing chute body, an overflow injection branch pipe, an underflow injection branch pipe and an injection branch pipe, and the overflow injection branch pipe and the underflow injection branch pipe are symmetrically arranged on the two sides of the wall of the material mixing chute body; the overflow injection branch pipe and the underflow injection branch pipe are provided with more than two injection branch pipes along the pipeline direction and are distributed on two sides in a staggered manner, pipe orifices of the injection branch pipes are arranged along the resultant vector direction, and the pipe orifices of the injection branch pipes are subjected to bidirectional cross jet flow to form a self-sustaining vortex ring to move forwards. A stirring pump is replaced by the unpowered design of the material mixing chute, meanwhile, the mixing uniformity of underflow overflow is higher, unpowered gradient self-flow of washing water can be achieved by taking water potential as kinetic energy through the height grading arrangement of the tank body, the use amount of pipelines is reduced through the pipeline design, and meanwhile, a better red mud settling and washing effect is achieved.

Description

Technical Field

[0001] This invention relates to the field of alumina production technology, and in particular to a vortex-ring mixing red mud sedimentation separation and washing device, application system and method. Background Technology

[0002] In the Bayer process of alumina production, the sedimentation, separation, and washing of the diluted slurry after leaching are key factors affecting the system's alkali recovery rate and operating energy consumption. The existing technology, CN103848449A, discloses a comprehensive filtration process for alumina production. This process involves (1) the coarse liquid from the red mud sedimentation and washing process entering a leaf filter via a coarse liquid tank and pump; (2) the refined liquid obtained after filtration entering a plate heat exchanger via a refined liquid pump to exchange heat with the mother liquor from the seed filtration process's mother liquor tank; (3) the underflow from the hydrocyclone in the seed decomposition process flowing by gravity to a flat plate filter; (4) the mother liquor obtained from the vertical and horizontal plate filters flowing by gravity to the seed filtration mother liquor tank; (5) the aluminum hydroxide obtained from the flat plate filter being transported by a belt conveyor to the aluminum hydroxide calcination process; and (6) the filter cake obtained from the leaf filter being sent to the red mud sedimentation and washing process. However, the following problems still exist:

[0003] 1. High dependence on power: The overflow washing chain relies on pump sets to realize the overflow reverse conveying. To realize a five-stage washing system, at least 4 overflow pumps are required. Not only does the energy consumption account for more than 35% of the total power consumption of the process, but it also increases the risk of failure and downtime (pump failure rate accounts for 62% of unplanned downtime events in the system).

[0004] 2. Poor mixing uniformity: The wash water and high-viscosity red mud bottom flow in the final washing stage are difficult to homogenize quickly. Traditional mechanical stirring mixing methods have short-circuit flow and dead zones, resulting in a loss of 0.8-1.2% (calculated as Na2O) in the alkali recovery rate.

[0005] 3. The overflow washing pipeline process is complex: In order to ensure that the normal operation is not affected even if the overflow pump fails, a backup pump combination is usually considered. At the same time, the pipeline from the pump to the top of the tank also increases the number of pipelines running up and down.

[0006] To address the aforementioned shortcomings, this invention proposes a four-dimensional innovative red mud treatment system integrating "parallel separation, gradient self-flow, vortex ring mixing, and dynamic mutual backup," which improves work efficiency through structural optimization. Summary of the Invention

[0007] A red mud washing device with vortex ring mixing includes a mixing sluice, which comprises a mixing sluice body, an underflow injection branch pipe, an overflow injection branch pipe, and a jet branch pipe. The overflow injection branch pipe and the underflow injection branch pipe are symmetrically arranged on both sides of the sluice body. The overflow injection branch pipe and the underflow injection branch pipe have two or more jet branch pipes along the pipeline direction and are staggered on both sides. The nozzles of the jet branch pipes are arranged along the resultant vector direction, and the bidirectional cross jets through the nozzles of the jet branch pipes form a self-sustaining vortex ring that moves forward.

[0008] Furthermore, taking the direction of the overflow injection branch pipe as the X-axis, the direction perpendicular to the overflow injection branch pipe in the plane containing the X-axis as the Y-axis, and the direction perpendicular to the XY plane as the Z-axis, the resultant vector direction of the nozzle of the spray branch pipe located on the overflow injection branch pipe is defined by a deflection of 15°-25° towards the Y-axis and an inclination of 35°-45° towards the Z-axis; the resultant vector direction of the nozzle of the spray branch pipe located on the underflow injection branch pipe is symmetrically arranged with respect to the nozzle of the spray branch pipe on the overflow injection branch pipe; the distribution interval of the spray branch pipes on both sides of the mixing chute wall is 100mm-150mm.

[0009] A red mud washing system using the aforementioned vortex-ring mixing red mud washing device includes: a first separation settling tank, a second settling separation tank, a first washing settling tank, a second washing settling tank, a third washing settling tank, a fourth washing settling tank, and a fifth washing settling tank; a first separation underflow pump, a second separation underflow pump, a first washing underflow pump, a second washing underflow pump, a third washing underflow pump, a fourth washing underflow pump, and a fifth washing underflow pump; the upper ends of the first washing settling tank to the fifth washing settling tank are provided with mixing chutes as described in claim 1; the upper ends of the first separation settling tank are respectively connected to raw material inputs. The overflow from the pipe and tank leads to the next process output pipe. The underflow from the lower end of the first separation settling tank is connected to the first separation underflow pump via a pipeline. The first separation underflow pump is connected to the mixing chute of the first washing settling tank via a pipeline. The overflow from the first washing settling tank is connected to the first washing overflow pump via a pipeline. The first washing overflow pump is connected to the next process output pipe. The overflow from the mixing chute of the first washing settling tank to the upper end of the mixing chute of the fifth washing settling tank is connected in series via a pipeline. The upper end of the fifth washing settling tank is also connected to a wash water input pipe. The overflow from the first washing settling tank to the... The underflow from the lower end of the fifth washing settling tank is connected via pipes to the first washing underflow pump and then to the fifth washing underflow pump. The underflow from the lower end of the first washing settling tank is pumped by the first washing underflow pump to the mixing chute of the second washing settling tank, while the overflow from the third washing settling tank flows by gravity through a pipe to the mixing chute of the second washing settling tank. The underflow from the lower end of the second washing settling tank is pumped by the second washing underflow pump to the mixing chute of the third washing settling tank, while the overflow from the fourth washing settling tank flows by gravity through a pipe to the third washing settling tank. The mixing chute of the tank; the underflow at the lower end of the third washing settling tank is pumped to the mixing chute of the fourth washing settling tank by the third washing underflow pump, while the overflow of the fifth washing settling tank flows by gravity through a pipe to the mixing chute of the fourth washing settling tank; the underflow at the lower end of the fourth washing settling tank is connected to the mixing chute of the fifth washing settling tank by the fourth washing underflow pump, while the wash water flows by gravity through a pipe to the mixing chute of the fifth washing settling tank; the underflow at the lower end of the fifth washing settling tank is connected to the output pipe of the next process by the fifth washing underflow pump.

[0010] Furthermore, the upper ends of the first separation settling tank and the second settling separation tank are connected in parallel to a raw material input pipe. The underflow at the lower end of the second settling separation tank is connected to a second separation underflow pump via a pipeline. The second separation underflow pump is connected to the mixing chute of the first washing settling tank via a pipeline. A common settling tank is provided between the second separation settling tank and the first washing settling tank. The upper ends of the second separation settling tank and the common settling tank are connected in parallel to a raw material input pipe. The underflow at the lower end of the common settling tank is connected to a common separation underflow pump via a pipeline. The common separation underflow pump is connected to the mixing chute of the first washing settling tank via a pipeline. The overflow at the upper end of the second washing settling tank is also connected to a second washing overflow pump via a pipeline. The second washing overflow pump is connected to the output pipe of the next process.

[0011] Furthermore, the upper ends of the fourth washing settling tank and the fifth washing settling tank are connected in parallel with a wash water input pipe; the overflow pipelines from the mixing chute of the fifth washing settling tank to the upper end of the mixing chute of the first washing settling tank are interconnected.

[0012] Furthermore, the installation foundations of the first separation settling tank to the fifth washing settling tank are at the same elevation, and the tank height is graded as follows:

[0013] The height of the first separation settling tank and the second settling separation tank from the first washing settling tank and the second washing settling tank is H1. The first separation settling tank (to the overflow port of the second washing settling tank) is arranged in a stepped manner at the same height, with a step height difference of 600mm-900mm.

[0014] The height of the third washing settling tank and the fourth washing settling tank is H2, and the difference between H2 and H1 is 1m-2.5m. The overflow outlets of the third washing settling tank and the fourth washing settling tank are arranged in a stepped manner at the same height, and the height difference between the steps is 600mm-900mm.

[0015] The height of the fifth washing and settling tank is H3, which is greater than H2, and the difference between the two is 1m-2.5m.

[0016] A method for operating a red mud washing system using the aforementioned vortex-ring mixing red mud washing apparatus includes the following steps:

[0017] a. Raw materials are fed into the first settling and separation tank for solid-liquid separation. The separation overflow is sent to the next process for controlled filtration. The separated underflow is fed into the mixing chute at the upper end of the first washing and settling tank via the first separation underflow pump. After mixing, it is discharged back into the first washing and settling tank.

[0018] b. The overflow of the first washing settling tank is sent to the next process for controlled filtration as a primary washing liquid via the first washing overflow pump. Its underflow is fed into the mixing chute of the second washing settling tank via the first washing underflow pump and the overflow of the third washing settling tank, respectively. After mixing, it is discharged into the second washing settling tank.

[0019] c. The overflow of the second washing settling tank is used as secondary washing liquid and the separation underflow of step a, respectively input into the mixing chute at the upper end of the first washing settling tank. After mixing, it is discharged into the first washing settling tank. Its underflow is fed into the mixing chute of the third washing settling tank through the second washing underflow pump and the overflow of the fourth washing settling tank. After mixing, it is discharged into the third washing settling tank.

[0020] d. The overflow of the third washing and settling tank is fed into the mixing chute at the upper end of the second washing and settling tank as the tertiary washing liquid and the underflow of the first washing and settling tank, respectively. After mixing, it is discharged into the second washing and settling tank. Its underflow is fed into the mixing chute at the upper end of the fourth washing and settling tank through the third washing underflow pump and the overflow of the fifth washing and settling tank, respectively. After mixing, it is discharged into the fourth washing and settling tank.

[0021] e. The overflow of the fourth washing and settling tank is used as the fourth washing liquid and is fed into the mixing chute at the upper end of the third washing and settling tank along with the underflow of the second washing and settling tank. After mixing, the mixture is discharged into the third washing and settling tank. The underflow of the mixture is fed into the mixing chute at the upper end of the fifth washing and settling tank along with the red mud washing water from the fifth washing and settling tank via the fourth washing underflow pump. After mixing, the mixture is discharged into the fifth washing and settling tank.

[0022] f. The overflow of the fifth washing and settling tank is fed into the mixing chute at the upper end of the fourth washing and settling tank as the fifth washing liquid and the underflow of the third washing and settling tank, respectively. After mixing, the mixture is discharged into the fourth washing and settling tank, and its underflow is output to the red mud mixing tank of the next process by the fifth washing underflow pump.

[0023] Further methods include the following steps:

[0024] a. Raw materials are fed into the first settling separation tank and the second settling separation tank in parallel for solid-liquid separation. The separation overflow is sent to the next process for controlled filtration. The separated underflow is fed into the mixing chute at the top of the second washing settling tank by the first separation underflow pump and the second separation underflow pump respectively. After mixing, it is discharged into the second washing settling tank.

[0025] b. The overflow of the second washing settling tank is sent as primary washing liquid to the next process for controlled filtration via the second washing overflow pump. Its underflow is fed into the mixing chute of the third washing settling tank via the second washing underflow pump and the overflow of the fourth washing settling tank, respectively. After mixing, it is discharged into the third washing settling tank.

[0026] c. The overflow of the third washing and settling tank is used as secondary washing liquid and the separation underflow of step a, respectively input into the mixing chute at the upper end of the second washing and settling tank. After mixing, it is discharged into the second washing and settling tank. Its underflow is fed into the mixing chute of the fourth washing and settling tank through the third washing underflow pump and the overflow of the fifth washing and settling tank, respectively. After mixing, it is discharged into the fourth washing and settling tank.

[0027] d. The overflow of the fourth washing and settling tank is fed into the mixing chute at the upper end of the third washing and settling tank as the tertiary washing liquid and the underflow of the second washing and settling tank, respectively. After mixing, it is discharged into the third washing and settling tank. Its underflow is fed into the mixing chute at the upper end of the fifth washing and settling tank through the fourth washing underflow pump and the red mud washing water of the fifth washing and settling tank, respectively. After mixing, it is discharged into the fifth washing and settling tank.

[0028] e. The overflow of the fifth washing and settling tank is fed into the mixing chute at the upper end of the fourth washing and settling tank as the fourth washing liquid and the underflow of the third washing and settling tank, respectively. After mixing, the mixture is discharged into the fourth washing and settling tank, and its underflow is output to the red mud mixing tank of the next process by the fifth washing underflow pump.

[0029] Further methods include the following steps:

[0030] a. Raw materials are fed into the first settling and separation tank for solid-liquid separation. The separation overflow is sent to the next process for controlled filtration. The separated underflow is fed into the mixing chute at the upper end of the first washing and settling tank via the first separation underflow pump. After mixing, it is discharged back into the first washing and settling tank.

[0031] b. The overflow of the first washing settling tank is sent to the next process for controlled filtration as a primary washing liquid via the first washing overflow pump. Its underflow is fed into the mixing chute of the third washing settling tank via the first washing underflow pump and the overflow of the fifth washing settling tank, respectively. After mixing, it is discharged into the third washing settling tank.

[0032] c. The overflow of the third washing and settling tank is used as secondary washing liquid and the separation underflow of step a, respectively input into the mixing chute at the upper end of the first washing and settling tank. After mixing, it is discharged into the first washing and settling tank. Its underflow is fed into the mixing chute of the fifth washing and settling tank through the third washing underflow pump and the red mud washing water of the fifth washing and settling tank. After mixing, it is discharged into the fifth washing and settling tank.

[0033] d. The overflow of the fifth washing and settling tank is fed into the mixing chute at the upper end of the third washing and settling tank as the tertiary washing liquid and the underflow of the first washing and settling tank, respectively. After mixing, the mixture is discharged into the third washing and settling tank, and its underflow is output to the red mud mixing tank of the next process by the fifth washing underflow pump.

[0034] A further method involves introducing the red mud wash water via an overflow washing process, specifically:

[0035] The red mud washing water is input from the mixing chute at the upper end of the fifth washing and settling tank; the resulting washing liquid flows in the opposite direction in the form of overflow through the fourth washing and settling tank → the third washing and settling tank → the second washing and settling tank → the first washing and settling tank.

[0036] Finally, the overflow from the first washing settling tank is transported to the dissolution and dilution process via the first washing overflow pump.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] 1. Red mud settling and washing: Underflow and overflow are introduced through the underflow injection branch pipe and overflow injection branch pipe of the mixing chute. Then, the overflow and underflow are sprayed out through the spray branch pipe at a specific angle to form a water flow vortex in the chute to accelerate the mixing uniformity of the underflow and overflow. The mixed washing liquid is then discharged into the material well, where it is fully mixed with additives before being discharged into each settling tank for a circulating washing process. In existing technologies, a stirring pump is usually added to mix the underflow and overflow. The mixing chute's non-powered design replaces the stirring pump, which improves the mixing uniformity of the underflow and overflow and allows the liquid in the underflow and overflow in the material well to react more fully with the additives, achieving a better settling effect. This results in a higher alkali content in the discharged washing underflow, improving the alkali recovery efficiency.

[0039] 2. By setting the tank height in stages, the washing water can achieve gradient self-flow without power by using the water potential as kinetic energy. This allows the upper clear liquid overflowing from each washing and settling tank to be recycled as washing water for the lower washing and settling tanks. In this way, only the fifth washing and settling tank, which is the highest-level tank, needs to be filled with red mud washing water, thereby saving water and reducing production costs.

[0040] 3. By connecting the underflow pump to the underflow of each tank, the underflow of the previous tank and the gradient gravity overflow of the next tank are mixed evenly in the mixing chute of the middle tank, and then discharged into the feeding well of the middle tank to fully mix and react with the additives. This pipeline design reduces the amount of pipeline used, while achieving a better red mud settling and washing effect. Attached Figure Description

[0041] Figure 1This is a schematic diagram of the mixing chute of the present invention.

[0042] Figure 2 This is a process flow diagram of the present invention.

[0043] Reference numerals in the attached drawings: 1-First separation settling tank, 2-Second separation settling tank, 3-First washing settling tank, 4-Second washing settling tank, 5-Third washing settling tank, 6-Fourth washing settling tank, 7-Fifth washing settling tank, 8-First separation underflow pump, 9-Second separation underflow pump, 10-First washing underflow pump, 11-Second washing underflow pump, 12-Third washing underflow pump, 13-Fourth washing underflow pump, 14-Fifth washing underflow pump, 15-Mixing chute, 15-1-Mixing chute body, 15-2-Overflow injection branch pipe, 15-3-Underflow injection branch pipe, 15-4-Jet branch pipe, 16-Spare separation settling tank, 17-Spare separation underflow pump, 18-First washing overflow pump, 19-Second washing overflow pump, 20-Feeding well. Detailed Implementation

[0044] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention in any way.

[0045] Example 1: As Figures 1-2 As shown. A vortex-ring mixing red mud settling and separation washing device includes a mixing sluice 15. The mixing sluice 15 is provided with a mixing sluice body 15-1, an overflow injection branch pipe 15-2, an underflow injection branch pipe 15-3, and a jet branch pipe 15-4. The overflow injection branch pipe 15-2 and the underflow injection branch pipe 15-3 are symmetrically arranged on both sides of the sluice body 15-1. The overflow injection branch pipe 15-2 and the underflow injection branch pipe 15-3 are provided with two or more jet branch pipes 15-4 along the pipeline direction and are staggered on both sides. The nozzles of the jet branch pipes 15-4 are arranged along the composite vector direction. The jets through the nozzles of the jet branch pipes 15-4 form a self-sustaining vortex ring that moves forward.

[0046] With the direction of the overflow injection branch pipe 15-2 as the X-axis, the direction perpendicular to the X-axis plane of the overflow injection branch pipe 15-2 as the Y-axis, and the direction perpendicular to the XY plane as the Z-axis, the resultant vector direction of the nozzle of the spray branch pipe 15-4 located on the overflow injection branch pipe 15-2 is defined by a deflection of 15°-25° towards the Y-axis and an inclination of 35°-45° towards the Z-axis; the resultant vector direction of the nozzle of the spray branch pipe 15-4 located on the underflow injection branch pipe 15-3 is symmetrically arranged with respect to the nozzle of the spray branch pipe 15-4 located on the overflow injection branch pipe 15-2; the distribution interval of the spray branch pipes 15-4 on both sides of the tank wall of the mixing chute 15-1 is 100mm-150mm.

[0047] The mixing chute 15 can simultaneously introduce underflow and overflow through the overflow injection branch pipe 15-2 and the underflow injection branch pipe 15-3. By using the set jet branch pipe 15-4 to perform cross jetting at the above-mentioned specific deflection angle, a vortex ring with good effect can be formed.

[0048] In cross-jet flow, the interaction between the jet and the mainstream induces complex flow phenomena. These vortices inherently possess vortex ring structures. For example, near the jet exit, shear layer instability generates jet shear layer vortices, whose vortex systems exhibit vortex ring structures. These vortex rings interact with each other and may even merge.

[0049] Furthermore, when two jets are ejected at an intersecting angle, their interaction forms a more complex vortex structure. In the near-field region of the jet, four types of vortex structures may coexist: jet shear layer vortices, horseshoe vortex systems, wake vortices, and opposing vortex pairs. Among these, the formation of jet shear layer vortices and opposing vortex pairs is closely related to vortex rings. Opposing vortex pairs, as a pair of vortex structures rotating in opposite directions on the flow cross section, are initiated by the roll-up of vortex rings in the shear layer at the jet boundary.

[0050] In Holman fluid mechanics, when a liquid is subjected to an external force, it flows. Due to the viscosity of the fluid, minute frictional forces are generated. The fluid with higher velocity decelerates, while the fluid with lower velocity accelerates. When a velocity difference exists in the fluid flow, it begins to rotate, forming a vortex. Impact deceleration and pressure increase cause the water flow at the annular interface to move along the boundary, forming a circulation that drives the outer water layer to rotate as well. The vortex ring created by the water flow is actually a series of interconnected vortex tubes, forming a ring-shaped hollow water vortex. The water in the cross-section rotates around the vortex tube, causing the water flow in the outer ring to flow backward, increasing the velocity and decreasing the pressure. The water in the inner ring overflows and moves forward, canceling out the velocity and slowing down the flow, increasing the pressure. This results in the Magnus effect, causing the ring to be pushed by the radial water pressure difference, continuing to expand. The gas inside the ring shrinks at the cross-section to maintain the air pressure, causing the vortex ring to advance, expand, and become thinner. The water flow velocity in the vortex ring section increases from the outside to the inside. The water pressure in the inner ring is low and is restricted to its original position by the pressure in the outer ring. At the same time, the pressure difference is perpendicular to the tangent of the water flow, so that the water flow only bears the centripetal force of the circular motion and does not bear the reverse pressure gradient. This allows the rotational kinetic energy to be maintained with less loss, so that the vortex ring can rotate and maintain a circular state.

[0051] Experimental design conditions:

[0052] 1. Tank geometry constraints (design determined): Determine the length, width, and height.

[0053] 2. Process fluid parameters: underflow density > mixed working fluid density > wash water density. The dynamic viscosity of the mixed working fluid is lower than the dynamic viscosity of the underflow. The total injection flow rate is calculated from the underflow volumetric flow rate and the wash water volumetric flow rate.

[0054] 3. Performance targets: The target vortex ring diameter should be smaller than the groove width, the mixing time t should be as short as possible, and the final fluid outlet mixing uniformity should meet the standard.

[0055] Hydrodynamic estimation of characteristic dimensions of vortex rings:

[0056] 1. The formation of vortex rings follows vorticity dynamics, and their final stable size is determined by both jet impulse and environmental fluid constraint.

[0057] 2. Calculate momentum flux.

[0058] 3. Estimate the formation time (t).

[0059] 4. Substitute the values ​​to estimate the vortex ring size.

[0060] 5. Introducing Spatial Constraints and Empirical Corrections: Within a highly confined, elongated channel, the vortex ring size is primarily controlled by the channel width. The channel width is the primary constraint determining the final vortex ring size. The design goal of the jet parameters is no longer to "generate" a vortex ring, but rather to "generate a high-energy, stable vortex ring that fills approximately half the channel width."

[0061] Detailed calculation of jet angle and collision dynamics: The jet angle determines the momentum transfer efficiency and the direction of vortex ring motion. The jet collision point is calculated (the left and right sides of the jet are symmetrical).

[0062] Design objectives and constraints:

[0063] 1. Mixing effect: Within a very short time (<10 seconds), the high-viscosity red mud bottom flow and wash water are made highly uniform.

[0064] 2. Flow requirements: The generated vortex ring must be able to move stably along the overflow direction (i.e., the length of the tank) to complete the mixing task for the entire length of the tank.

[0065] 3. Space constraints (to be determined by design based on actual conditions): The size of the mixing chute is fixed, and the vortex ring must be generated and developed within a limited space. It cannot collide violently with the chute wall, which would cause premature energy dissipation.

[0066] 4. Energy consumption limitation: Only the kinetic energy of the fluid itself is used, without adding any additional power (non-powered mixing).

[0067] Assuming the tank width is 0.8m, an ideal vortex ring should effectively agitate the entire tank width without being too large to rub against the tank walls. A diameter of 0.4m is optimal, approximately half the tank width. This is an empirically validated proportion from production testing, ensuring the vortex ring is stably generated and moves in the center, and its induced flow field sufficiently disturbs the fluids on both sides.

[0068] 5. Jet Angle: The horizontal angle (Y-axis) primarily determines the formation position and direction of motion of the vortex ring, causing the jets on both sides to collide, converge, and entrain each other near the centerline of the chute, thus forming a stable vortex ring. The downward angle (Z-axis) primarily determines the generation efficiency and energy utilization rate of the vortex ring. The jet momentum must be effectively converted into the rotational kinetic energy of the vortex ring, while avoiding direct impact on the chute bottom to prevent energy loss. The final jet direction is the result of the combination of these two angles.

[0069] The vector composition rule can be used to combine two angles. Suppose we have two vectors, a and b, with magnitudes |a| and |b|, and directions θ1 and θ2, respectively. Their combined vector can be expressed by the following formula:

[0070] c = a + b.

[0071] Where c is the magnitude of the composite vector, and θ3 is the direction of the composite vector. Based on the properties of trigonometric functions, we can derive the following formulas to calculate the magnitude and direction of the composite vector:

[0072] c = √(a^2 + b^2 + 2abcos(θ2-θ1)).

[0073] θ3 = arctan((bsin(θ2) + asin(θ1)) / (bcos(θ2) + acos(θ1))).

[0074] Imagine a cone. Ideally, the central axis should be at a 40° angle to the horizontal plane, and the jet direction should be the generatrix on the cone surface at a 20° angle to the central axis. This can generate a vortex ring of about 0.4 meters. This ensures that the jets on both sides collide symmetrically and precisely, providing enough vertical momentum to efficiently generate the vortex ring, while also ensuring enough horizontal momentum to drive the vortex ring forward.

[0075] When the resultant vector direction of the nozzle of the injection branch pipe 15-4 deflects 15° towards the Y-axis and then tilts 35° towards the Z-axis, the diameter of the generated vortex ring is about 0.3 meters; when the resultant vector direction of the nozzle of the injection branch pipe 15-4 deflects 25° towards the Y-axis and then tilts 45° towards the Z-axis, the diameter of the generated vortex ring is about 0.5 meters.

[0076] As long as the water flow is continuous, the vortex ring can maintain its operation for an extended period, ensuring uniform mixing of the underflow and overflow in the mixing sluice 15. The vortex ring moves along the overflow direction, enhancing turbulence intensity through jet interference, thus achieving rapid mixing of the underflow and wash water. It also allows the mixed water to settle more quickly into the introduced tank along the vortex ring's direction of motion. To prevent rainwater from entering the production process, a movable cover or a simple supporting rain cover can be installed on the top of the mixing sluice 15.

[0077] A red mud washing system using a vortex-ring mixing red mud washing device includes: a first separation settling tank 1, a second settling separation tank 2, a first washing settling tank 3, a second washing settling tank 4, a third washing settling tank 5, a fourth washing settling tank 6, and a fifth washing settling tank 7; a first separation underflow pump 8, a second separation underflow pump 9, a first washing underflow pump 10, a second washing underflow pump 11, a third washing underflow pump 12, a fourth washing underflow pump 13, and a fifth washing underflow pump 14; the upper ends of the first washing settling tank 3 to the fifth washing settling tank 7 are provided with mixing chutes 15 as described in claim 1; the upper ends of the first separation settling tank 1 are respectively connected to raw material input pipes. The overflow from the first washing and settling tank 1 is connected to the next process output pipe via a pipeline. The underflow from the lower end of the first separation settling tank 1 is connected to the first separation underflow pump 8 via a pipeline. The first separation underflow pump 8 is connected to the mixing chute 15 of the first washing and settling tank 3 via a pipeline. The overflow from the first washing and settling tank 3 is connected to the first washing overflow pump 18 via a pipeline. The first washing overflow pump 18 is connected to the next process output pipe. The overflow from the mixing chute 15 of the first washing and settling tank 3 to the upper end of the mixing chute 15 of the fifth washing and settling tank 7 is connected in series via a pipeline. The upper end of the fifth washing and settling tank 7 is also connected to a wash water input pipe. The overflow from the first washing and settling tank 3 to the fifth washing and settling tank 7 is connected in series via a pipeline. The underflow at the lower end of the washing settling tank 7 is connected via pipes to the first washing underflow pump 10 and the fifth washing underflow pump 14 respectively; the underflow at the lower end of the first washing settling tank 3 is pumped by the first washing underflow pump 10 to the mixing chute 15 of the second washing settling tank 4, while the overflow of the third washing settling tank 5 flows by gravity through a pipe to the mixing chute 15 of the second washing settling tank 4; the underflow at the lower end of the second washing settling tank 4 is pumped by the second washing underflow pump 11 to the mixing chute 15 of the third washing settling tank 5, while the overflow of the fourth washing settling tank 6 flows by gravity through a pipe to the third washing settling tank 5. The mixing chute 15; the underflow from the lower end of the third washing settling tank 5 is pumped to the mixing chute 15 of the fourth washing settling tank 6 by the third washing underflow pump 12, and the overflow from the fifth washing settling tank 7 flows by gravity through a pipe to the mixing chute 15 of the fourth washing settling tank 6; the underflow from the lower end of the fourth washing settling tank 6 is connected to the mixing chute 15 of the fifth washing settling tank 7 by the fourth washing underflow pump 13, and the wash water flows by gravity through a pipe to the mixing chute 15 of the fifth washing settling tank 7; the underflow from the lower end of the fifth washing settling tank 7 is connected to the output pipe of the next process by the fifth washing underflow pump 14.

[0078] The feed inlet of the mixing chute 15 is connected to the feeding well 20, which is located at the top of the interior of the first washing and settling tank 3 to the fifth washing and settling tank 7.

[0079] The bottom of the material well is uniformly perforated with multiple small holes. These holes are key to achieving efficient washing and separation, enabling uniform liquid distribution to enhance mass transfer, facilitating stable underflow discharge, optimizing countercurrent washing circulation, and ensuring sedimentation and separation efficiency. Ultimately, this maximizes the recovery of Al2O3 and Na2O from the red mud adsorbate, reducing alkali consumption and environmental risks (such as pH control of discharged red mud). This design is closely matched with the high dispersibility and colloidal properties of red mud and the countercurrent washing process, representing a crucial detail for improving resource utilization in alumina production.

[0080] The installation foundations of the first separation settling tank, the second separation settling tank, the first washing settling tank, the second washing settling tank, the third washing settling tank, the fourth washing settling tank, and the fifth washing settling tank of this washing system are at the same elevation, and the tank height is set in stages as follows:

[0081] The height of the first separation settling tank 1, the second settling separation tank 2, the first washing settling tank 3 and the second washing settling tank 4 is H1. The overflow ports of the first separation settling tank 1 to the second washing settling tank 4 are arranged in a stepped manner at the same height, with a step height difference of 600mm-900mm.

[0082] The height of the third washing settling tank 5 and the fourth washing settling tank 6 is H2, and the difference between H2 and H1 can be 1m-2.5m. The overflow outlets of the third washing settling tank 5 and the fourth washing settling tank 6 are arranged in a stepped manner at the same height, and the difference in step height is 600mm-900mm.

[0083] The height of the fifth washing and settling tank 7 is H3, which is greater than H2, and the difference between the two is 1m-2.5m.

[0084] The first separation settling tank 1 and the second settling separation tank 2 have the same diameter as the washing settling tanks. However, because the solid-liquid separation efficiency of the separation tanks in handling unwashed slurry is lower than that of the washing tanks, the processing capacity per unit time decreases. Therefore, two settling separation tanks of the same diameter are set up in parallel to meet the production capacity requirements of a 2 million-ton alumina plant. The parallel connection through pipelines is to meet the requirements. According to this scale, the optimal dimensions for the washing settling tanks are 3.5 meters long, 0.8 meters wide, and 1.2 meters high. The separation settling tanks can be increased or decreased according to the production scale. The separation settling tanks connect the raw material (diluted slurry after leaching) and the overflow control filtration process. The settled underflow is pumped to the subsequent washing settling tanks by the separation underflow pump. Then, the washing settling tanks are set up with different heights. The overflow from the previous stage flows by gravity to the subsequent washing tanks, realizing pump-free power transportation. This allows for the reuse of the upper clear liquid overflowing from each tank, thereby saving the amount of washing water.

[0085] The overflow from the upper end of the first washing settling tank 3 is connected to the first washing overflow pump 18 through a pipeline, and the primary washing liquid is discharged by the first washing overflow pump 18 to the leaching process for dilution slurry. The overflow from the upper end of the second washing settling tank 4 is connected to the second washing overflow pump 19 through a pipeline, and the second washing overflow pump 19 discharges the secondary washing liquid to the leaching process for dilution slurry.

[0086] A backup settling tank 16 is provided between the second separation settling tank 2 and the first washing settling tank 3. The upper end of the backup settling tank 6 is connected to the input pipe of the slurry leaching and dilution liquid, and the underflow at the lower end is connected to the backup separation underflow pump 17 through a pipe. The backup separation underflow pump 17 sends the underflow to the mixing chute 15 at the upper end of the second washing settling tank 4.

[0087] The number of settling and washing tanks is matched with the number of washing cycles. By configuring a pipeline switching system, the following emergency failure modes can be achieved: when the first settling separation tank 1, the second settling separation tank 2, or the first settling and washing tank 3 fails, the public backup settling tank 16 takes over its function; when any two adjacent washing and settling tanks fail, mutual backup operation can also be achieved by switching tanks through the pipeline process.

[0088] To achieve better washing results with the aforementioned washing system, a method for using the system was designed, which includes the following steps:

[0089] a. Raw materials are fed into the first settling and separation tank 1 for solid-liquid separation. The separation overflow is sent to the next process for controlled filtration. The separated underflow is fed into the mixing chute 15 at the upper end of the first washing and settling tank 3 via the first separation underflow pump 8. After mixing, it is discharged into the first washing and settling tank 3.

[0090] b. The overflow of the first washing settling tank 3 is sent to the next process for controlled filtration as a primary washing liquid via the first washing overflow pump 18. Its underflow is fed into the mixing chute 15 of the second washing settling tank 4 via the first washing underflow pump 10 and the overflow of the third washing settling tank 5, respectively. After mixing, it is discharged into the second washing settling tank 4.

[0091] c. The overflow of the second washing settling tank 4 is used as secondary washing liquid and the separation underflow of step a, respectively input into the mixing chute 15 at the upper end of the first washing settling tank 3. After mixing, it is discharged into the first washing settling tank 3. Its underflow is fed into the mixing chute 15 of the third washing settling tank 5 through the second washing underflow pump 11 and the overflow of the fourth washing settling tank 6, respectively. After mixing, it is discharged into the third washing settling tank 5.

[0092] d. The overflow of the third washing settling tank 5 is fed into the mixing chute 15 at the upper end of the second washing settling tank 4 as the tertiary washing liquid and the underflow of the first washing settling tank 3, respectively. After mixing, it is discharged into the second washing settling tank 4. Its underflow is fed into the mixing chute 15 at the upper end of the fourth washing settling tank 6 through the third washing underflow pump 12 and the overflow of the fifth washing settling tank 7, respectively. After mixing, it is discharged into the fourth washing settling tank 6.

[0093] e. The overflow of the fourth washing settling tank 6 is used as the fourth washing liquid and is fed into the mixing chute 15 at the upper end of the third washing settling tank 5 along with the underflow of the second washing settling tank 4. After mixing, the mixture is discharged into the third washing settling tank 5. The underflow of the mixture is fed into the mixing chute 15 at the upper end of the fifth washing settling tank 7 along with the red mud washing water from the fifth washing settling tank 7 via the fourth washing underflow pump 13. After mixing, the mixture is discharged into the fifth washing settling tank 7.

[0094] f. The overflow of the fifth washing and settling tank 7 is fed into the mixing chute 15 at the upper end of the fourth washing and settling tank 6 as the fifth washing liquid and the underflow of the third washing and settling tank 5, respectively. After mixing, the mixture is discharged into the fourth washing and settling tank 6, and its underflow is output to the red mud mixing tank of the next process through the fifth washing underflow pump 14.

[0095] This method involves mixing the underflow pumped from the previous tank with the overflow from the next tank and then transferring the mixture to the intermediate tank for washing. This saves on pipeline investment. At the same time, the operation of the underflow pump promotes the mixing of the underflow and overflow in the mixing chute, which saves on washing water consumption and increases the alkali content of the red mud after a single washing process.

[0096] The red mud washing water is washed via an overflow method as follows: the red mud washing water is input from the mixing chute 15 at the upper end of the fifth washing settling tank 7; the resulting washing liquid flows in the opposite direction in the form of overflow through the fourth washing settling tank 6 → the third washing settling tank 5 → the second washing settling tank 4 → the first washing settling tank 3. Finally, the overflow from the first washing settling tank 3 is transported to the leaching and dilution process by the first washing overflow pump 18. If the first washing overflow pump 18 fails, the second washing overflow pump 19 can take over the operation independently.

[0097] The device system and operating method designed by this invention can achieve the same production effect as conventional designs in the prior art. However, this invention saves the overflow pumps required for the second to fifth washing and settling tanks. Each settling tank conventionally requires two working overflow pumps and two backup overflow pumps, totaling 16 overflow pumps. Each overflow pump costs approximately 150,000 yuan. This invention uses only two overflow pumps, resulting in a total cost saving of 150,000 yuan * 14 pumps = 2,100,000 yuan. Each overflow pump has a motor power of 132 kW, saving a total of [amount missing] kW of operating motor power. The total power consumption is 132 * 6 = 792 KW. With equipment maintenance once a month (1 day / time), the annual power saving is approximately 792 KW * 24 hours * 353 days ≈ 6.71 million KW / h. At 0.5 yuan per kWh, the electricity cost saving is approximately 6.71 million * 0.5 = 3.35 million yuan. By mixing the underflow pump from the first tank with the overflow from the second tank before entering the intermediate tank for washing, pipeline investment can be reduced by approximately 20%-40%. The optimized pipeline design simplifies operations, reduces maintenance workload, and provides a more user-friendly environment for improving enterprise management.

[0098] Example 2: Figures 1-2 As shown. When the first separation settling tank 1 and the second settling separation tank 2 are malfunctioning and cannot be used, the backup separation settling tank 16 will take over the work. The upper end is connected to the input pipe of the diluted slurry after dissolution and the control filtration process of the overflow in the tank, respectively. The lower end of the separation underflow is connected to the backup separation underflow pump 17 through the pipeline. The underflow of the backup separation settling tank 16 is pumped by the backup separation underflow pump 17 to the mixing chute 15 of the first washing settling tank 3 and mixed with the overflow of the second washing settling tank 4 as secondary washing liquid before being discharged into the first washing settling tank 3.

[0099] The parallel connection of the first washing settling tank 3 and the second washing settling tank 4 to control the filtration process also serves as an emergency backup in case of failure: when the first washing settling tank 3 fails, the second washing settling tank 4 can take over its work alone. That is, the underflow from the liquid-solid separation settling tank 16 or the first settling separation tank 1 and the second settling separation tank 2 can also be directly pumped to the second washing settling tank 4 for washing.

[0100] The tank heights are graded as follows: the heights of the first separation settling tank 1 and the second settling separation tank 2, and the first washing settling tank 3 and the second washing settling tank 4 are H1; the heights of the third washing settling tank 5 and the fourth washing settling tank 6 are H2, where H2 = H1 + 1.5m; and the height of the fifth washing settling tank 7 is H3, where H3 = H2 + 1.5m. This height difference, where H3 is greater than H2 and H2 is greater than H1, allows for gradient gravity flow, saving on the cost of an overflow pump.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A red mud washing device with vortex ring mixing, comprising a mixing chute (15), characterized in that, The mixing chute (15) includes a mixing chute body (15-1), an overflow injection branch pipe (15-2), an underflow injection branch pipe (15-3), and a jet branch pipe (15-4). The overflow injection branch pipe (15-2) and the underflow injection branch pipe (15-3) are symmetrically arranged on both sides of the wall of the mixing chute body (15-1). The overflow injection branch pipe (15-2) and the underflow injection branch pipe (15-3) are provided with two or more jet branch pipes (15-4) along the pipeline direction and are staggered on both sides. The nozzles of the jet branch pipes (15-4) are arranged along the direction of the composite vector. The jets through the nozzles of the jet branch pipes (15-4) form a self-sustaining vortex ring that moves forward.

2. The vortex-ring mixing red mud washing device according to claim 1, characterized in that, With the direction of the overflow injection branch pipe (15-2) as the X-axis, the direction of the plane containing the X-axis perpendicular to the overflow injection branch pipe (15-2) as the Y-axis, and the direction perpendicular to the XY plane as the Z-axis, the resultant vector direction of the nozzle of the spray branch pipe (15-4) located on the overflow injection branch pipe (15-2) is defined by a deflection of 15°-25° towards the Y-axis and an inclination of 35°-45° towards the Z-axis; the resultant vector direction of the nozzle of the spray branch pipe (15-4) located on the bottom flow injection branch pipe (15-3) is symmetrically arranged with respect to the nozzle of the spray branch pipe (15-4) on the overflow injection branch pipe (15-2); the distribution interval of the spray branch pipe (15-4) on both sides of the mixing chute body (15-1) is 100mm-150mm.

3. A red mud washing system using the vortex-ring mixing red mud washing apparatus of claim 1 or 2, comprising: The first separation settling tank (1), the second settling separation tank (2), the first washing settling tank (3), the second washing settling tank (4), the third washing settling tank (5), the fourth washing settling tank (6), and the fifth washing settling tank (7), and the first separation underflow pump (8), the second separation underflow pump (9), the first washing underflow pump (10), the second washing underflow pump (11), the third washing underflow pump (12), the fourth washing underflow pump (13), and the fifth washing underflow pump (14), characterized in that the upper ends of the first washing settling tank (3) to the fifth washing settling tank (7) are provided with a mixing chute (15) as described in claim 1; the upper end of the first separation settling tank (1) is respectively connected to the raw material input pipe and the next process feed pipe overflowing from the tank. The underflow from the lower end of the first separation settling tank (1) is connected to the first separation underflow pump (8) via a pipeline, and the first separation underflow pump (8) is connected to the mixing chute (15) of the first washing settling tank (3) via a pipeline; the overflow from the first washing settling tank (3) is connected to the first washing overflow pump (18) via a pipeline, and the first washing overflow pump (18) is connected to the output pipe of the next process; the overflow from the mixing chute (15) of the first washing settling tank (3) to the upper end of the mixing chute (15) of the fifth washing settling tank (7) is connected in series via a pipeline, and the upper end of the fifth washing settling tank (7) is also connected to a wash water input pipe; the overflow from the first washing settling tank (3) to the lower end ... connected to a wash water input pipe; the overflow from the first washing settling tank (3) to the lower end of the fifth washing settling tank (7) is connected in series via a pipeline, and the upper end of the fifth washing settling tank (7) is connected to a wash water input pipe; the overflow from the first washing settling tank (3) to the lower end of the fifth washing settling tank (7) is connected in series via a pipeline, and the upper end of the fifth washing settling tank (7) is connected to a wash water input pipe; the overflow from the first washing settling tank (3) to the lower end of the fifth washing settling tank (7) is connected to the mixing chute (15) of the first washing settling tank (3) to the fifth washing settling tank (7) is connected to the mixing The underflow from the first washing underflow pump (10) is connected to the fifth washing underflow pump (14) via pipes. The underflow from the lower end of the first washing settling tank (3) is pumped by the first washing underflow pump (10) to the mixing chute (15) of the second washing settling tank (4), while the overflow from the third washing settling tank (5) flows by gravity through pipes to the mixing chute (15) of the second washing settling tank (4). The underflow from the lower end of the second washing settling tank (4) is pumped by the second washing underflow pump (11) to the mixing chute (15) of the third washing settling tank (5), while the overflow from the fourth washing settling tank (6) flows by gravity through pipes to the mixing chute (15) of the third washing settling tank (5). Tank (15); the underflow at the lower end of the third washing settling tank (5) is pumped by the third washing underflow pump (12) to the mixing chute (15) of the fourth washing settling tank (6), while the overflow of the fifth washing settling tank (7) flows by gravity through the pipe to the mixing chute (15) of the fourth washing settling tank (6); the underflow at the lower end of the fourth washing settling tank (6) is connected to the mixing chute (15) of the fifth washing settling tank (7) through the fourth washing underflow pump (13), while the wash water flows by gravity through the pipe to the mixing chute (15) of the fifth washing settling tank (7); the underflow at the lower end of the fifth washing settling tank (7) is connected to the output pipe of the next process through the fifth washing underflow pump (14).

4. The red mud washing system using a vortex-ring mixing red mud washing device according to claim 3, characterized in that, The upper ends of the first separation settling tank (1) and the second settling separation tank (2) are connected in parallel to the raw material input pipe. The underflow at the lower end of the second settling separation tank (2) is connected to the second separation underflow pump (9) through a pipeline. The second separation underflow pump (9) is connected to the mixing chute (15) of the first washing settling tank (3) through a pipeline. A common settling tank (16) is provided between the second separation settling tank (2) and the first washing settling tank (3). The upper ends of the second separation settling tank (2) and the common settling tank (16) are connected in parallel to the raw material input pipe. The underflow at the lower end of the common settling tank (16) is connected to the common separation underflow pump (17) through a pipeline. The common separation underflow pump (17) is connected to the mixing chute (15) of the first washing settling tank (3) through a pipeline. The overflow at the upper end of the second washing settling tank (4) is also connected to the second washing overflow pump (19) through a pipeline. The second washing overflow pump (19) is connected to the output pipe of the next process.

5. The red mud washing system using a vortex-ring mixing red mud washing device according to claim 3, characterized in that, The upper ends of the fourth washing settling tank (6) and the fifth washing settling tank (7) are connected in parallel with the washing water input pipe; the mixing chute (15) of the fifth washing settling tank (7) and the overflow series pipeline of the mixing chute (15) of the first washing settling tank (3) are interconnected.

6. The red mud washing system of the vortex-ring mixing red mud washing device according to claim 3, characterized in that, The first separation settling tank (1) to the fifth washing settling tank (7) have the same foundation elevation, and the tank height is set in stages as follows: The height of the first separation settling tank (1) and the second settling separation tank (2) is H1 with that of the first washing settling tank (3) and the second washing settling tank (4). The overflow ports of the first separation settling tank (1) to the second washing settling tank (4) are arranged in a stepped manner at the same height, with a step height difference of 600mm-900mm. The height of the third washing settling tank (5) and the fourth washing settling tank (6) is H2, and the difference between H2 and H1 is 1m-2.5m. The overflow ports of the third washing settling tank (5) and the fourth washing settling tank (6) are arranged in a stepped manner at the same height, and the difference in step height is 600mm-900mm. The height of the fifth washing and settling tank (7) is H3, which is greater than H2, and the difference between the two is 1m-2.5m.

7. A method for operating a red mud washing system using a vortex-ring mixing red mud washing apparatus according to any one of claims 3-6, characterized in that, Includes the following steps: a. Raw materials are fed into the first settling and separation tank (1) for solid-liquid separation. The separation overflow is sent to the next process for controlled filtration. The separated underflow is fed into the mixing chute (15) at the top of the first washing and settling tank (3) via the first separation underflow pump (8). After mixing, the mixture is discharged into the first washing and settling tank (3). b. The overflow of the first washing settling tank (3) is sent to the next process for controlled filtration as a primary washing liquid via the first washing overflow pump (18). Its underflow is fed into the mixing chute (15) of the second washing settling tank (4) via the first washing underflow pump (10) and the overflow of the third washing settling tank (5), respectively, and after mixing, it is discharged into the second washing settling tank (4). c. The overflow of the second washing settling tank (4) is used as secondary washing liquid and the separation underflow of step a, respectively input into the mixing chute (15) at the upper end of the first washing settling tank (3), and after mixing, it is discharged into the first washing settling tank (3). Its underflow is fed into the mixing chute (15) of the third washing settling tank (5) through the second washing underflow pump (11) and the overflow of the fourth washing settling tank (6), respectively, and after mixing, it is discharged into the third washing settling tank (5). d. The overflow of the third washing settling tank (5) is used as the tertiary washing liquid and the underflow of the first washing settling tank (3) respectively input into the mixing chute (15) at the upper end of the second washing settling tank (4), and after mixing, it is discharged into the second washing settling tank (4). Its underflow is fed into the mixing chute (15) at the upper end of the fourth washing settling tank (6) through the third washing underflow pump (12) and the overflow of the fifth washing settling tank (7), and after mixing, it is discharged into the fourth washing settling tank (6). e. The overflow of the fourth washing settling tank (6) is used as the fourth washing liquid and the underflow of the second washing settling tank (4) respectively input into the mixing chute (15) at the upper end of the third washing settling tank (5), and after mixing, it is discharged into the third washing settling tank (5). Its underflow passes through the fourth washing underflow pump (13) and the red mud washing water of the fifth washing settling tank (7) respectively input into the mixing chute (15) at the upper end of the fifth washing settling tank (7), and after mixing, it is discharged into the fifth washing settling tank (7). f. The overflow of the fifth washing settling tank (7) is fed into the mixing chute (15) at the top of the fourth washing settling tank (6) as the fifth washing liquid and the underflow of the third washing settling tank (5). After mixing, the mixture is discharged into the fourth washing settling tank (6), and its underflow is output to the red mud mixing tank of the next process through the fifth washing underflow pump (14).

8. The method according to claim 7, characterized in that, Includes the following steps: a. Raw materials are fed into the first settling separation tank (1) and the second settling separation tank (2) in parallel for solid-liquid separation. The separation overflow is sent to the next process for controlled filtration. The separated underflow is fed into the mixing chute (15) at the top of the second washing settling tank (4) by the first separation underflow pump (8) and the second separation underflow pump (9), respectively. After mixing, the mixture is discharged into the second washing settling tank (4). b. The overflow of the second washing settling tank (4) is sent to the next process for controlled filtration as a primary washing liquid via the second washing overflow pump (19). Its underflow is fed into the mixing chute (15) of the third washing settling tank (5) via the second washing underflow pump (11) and the overflow of the fourth washing settling tank (6), respectively. After mixing, it is discharged into the third washing settling tank (5). c. The overflow of the third washing settling tank (5) is used as secondary washing liquid and the separation underflow of step a, respectively input into the mixing chute (15) at the upper end of the second washing settling tank (4), and after mixing, it is discharged into the second washing settling tank (4). Its underflow is fed into the mixing chute (15) of the fourth washing settling tank (6) through the overflow of the third washing underflow pump (12) and the fifth washing settling tank (7), respectively, and after mixing, it is discharged into the fourth washing settling tank (6). d. The overflow of the fourth washing settling tank (6) is used as the third washing liquid and the underflow of the second washing settling tank (4) respectively input into the mixing chute (15) at the upper end of the third washing settling tank (5), and after mixing, it is discharged into the third washing settling tank (5). Its underflow passes through the fourth washing underflow pump (13) and the red mud washing water of the fifth washing settling tank (7) respectively input into the mixing chute (15) at the upper end of the fifth washing settling tank (7), and after mixing, it is discharged into the fifth washing settling tank (7). e. The overflow of the fifth washing settling tank (7) is used as the fourth washing liquid and the underflow of the third washing settling tank (5) respectively input into the mixing chute (15) at the upper end of the fourth washing settling tank (6), and after mixing, it is discharged into the fourth washing settling tank (6). Its underflow is output to the red mud mixing tank of the next process through the fifth washing underflow pump (14).

9. The method according to claim 7, characterized in that, Includes the following steps: a. Raw materials are fed into the first settling and separation tank (1) for solid-liquid separation. The separation overflow is sent to the next process for controlled filtration. The separated underflow is fed into the mixing chute (15) at the top of the first washing and settling tank (3) via the first separation underflow pump (8). After mixing, the mixture is discharged into the first washing and settling tank (3). b. The overflow of the first washing settling tank (3) is sent to the next process for controlled filtration as a primary washing liquid via the first washing overflow pump (18). Its underflow is fed into the mixing chute (15) of the third washing settling tank (5) via the first washing underflow pump (10) and the overflow of the fifth washing settling tank (7), respectively. After mixing, it is discharged into the third washing settling tank (5). c. The overflow of the third washing settling tank (5) is used as secondary washing liquid and the separation underflow of step a, respectively input into the mixing chute (15) at the upper end of the first washing settling tank (3), and after mixing, it is discharged into the first washing settling tank (3). Its underflow passes through the third washing underflow pump (12) and the red mud washing water of the fifth washing settling tank (7), respectively input into the mixing chute (15) of the fifth washing settling tank (7), and after mixing, it is discharged into the fifth washing settling tank (7). d. The overflow of the fifth washing settling tank (7) is fed into the mixing chute (15) at the top of the third washing settling tank (5) as the third washing liquid and the underflow of the first washing settling tank (3). After mixing, the mixture is discharged into the third washing settling tank (5), and its underflow is output to the red mud mixing tank of the next process through the fifth washing underflow pump (14).

10. The method according to claim 7, characterized in that, The red mud washing water is introduced through an overflow washing method, specifically: Red mud washing water is input from the mixing chute (15) at the upper end of the fifth washing settling tank (7); the resulting washing liquid flows in the opposite direction in the form of overflow through the fourth washing settling tank (6) → the third washing settling tank (5) → the second washing settling tank (4) → the first washing settling tank (3). Finally, the overflow from the first washing settling tank (3) is transported to the dissolution and dilution process via the first washing overflow pump (18).

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