Multistage rotor-stator nested coupling flotation machine

Abstract

The application discloses a multilayer rotor-stator nested flotation machine, which comprises a cylinder, the inside of the cylinder is divided into a stirring area and a separation area, a plurality of coupled rotor-stator assemblies are nested in the stirring area, the rotor-stator assemblies comprise an inner rotor, an outer rotor, an inner stator and an outer stator, the inner rotor and the outer rotor are coaxially fixedly connected to a stirring shaft, a flow baffle is fixed to the inner wall of the cylinder and located at the position of the separation area above the stirring area, a feeding port and a bottom air inlet are both communicated with the stirring area, a concentrate tank is arranged at the top end of the cylinder and communicated with the separation area, a concentrate outlet is arranged at the bottom of the concentrate tank, and a tailing outlet is arranged at the lower side wall of the cylinder. The multilayer rotor-stator nested coupling structure design constructs a multistage gradient turbulent mineralization system, strengthens the gas-particle collision efficiency, meets the differentiated separation requirements of coarse and fine particles, improves the flotation recovery rate and equipment integration, and reduces the production energy consumption and land cost.

Description

Technical Field

[0001] This invention relates to a multi-layer rotor-stator nested coupling flotation machine, which is suitable for the resource-based flotation and recovery of low-grade, fine-grained, wide-size mixed minerals and tailings. Background Technology

[0002] Foam flotation is a physicochemical separation technology that separates solid, liquid, and gaseous components based on the differences in surface wettability of mineral particles. It is currently the core mainstream technology and most effective means to solve the challenges of resource recovery from low-grade fine-grained disseminated minerals and micro-fine-grained tailings. Addressing the technical shortcomings of traditional physical separation processes such as gravity separation and magnetic separation in efficiently recovering micro-fine-grained valuable minerals, foam flotation can selectively hydrophobically modify the surface of micro-fine minerals through reagent control. Relying on the mechanisms of gas-particle collision, adhesion, and flotation enrichment, it achieves precise separation and recovery of micro-fine-grained valuable components, effectively overcoming the shortcomings of traditional separation processes such as poor adaptability to fine-grained materials and low recovery rates. Furthermore, foam flotation is not only suitable for the efficient mineralization separation of micro-fine-grained materials but also compatible with processing common industrial feed materials of mixed coarse and fine particle sizes. With a wide range of material adaptability and high separation control precision, it is a key core process for improving the comprehensive utilization rate of low-grade complex mineral resources and achieving tailings reduction and resource recovery at this stage. The complete froth flotation process encompasses multiple coupled continuous sub-processes, including slurry conditioning, particle surface modification, gas dispersion, gas-particle collision mineralization, aggregate stable transport, and froth layer enrichment. Its separation efficiency depends on the in-tank turbulence intensity, energy dissipation characteristics, and stable gas-particle mineralization environment provided by the flotation equipment.

[0003] Currently, my country's mineral resources are generally characterized by low grade, fine-grained dissemination, and complex composition. The proportion of fine-grained minerals in beneficiation feed and tailings products continues to rise, and the problems of difficulty in recovering valuable components from fine-grained particles and serious resource loss are becoming increasingly prominent. Due to the inherent physical properties of fine-grained minerals—small particle size, light weight, and weak inertia—they are easily swept around in the slurry flow field, resulting in low effective collision probability of air particles and poor mineralization adhesion stability, which has always been a common technical challenge in the field of mineral separation. Existing flotation equipment generally has inherent defects in its structural design, with a single form of turbulence excitation and poor matching between energy input and dissipation structure, failing to provide sufficient, uniform, and continuous kinetic conditions for efficient mineralization of fine particles. This leads to low flotation recovery rate, poor separation stability, and high consumption of reagents and energy. Meanwhile, most existing equipment is only suitable for sorting single narrow-sized materials. It is not adaptable enough to the wide-sized mixed slurry feeding conditions that are common in mines. It cannot take into account the differentiated sorting needs of efficient mineralization of fine particles and stable floating of coarse particles. Problems such as gangue mechanical entrainment and particle desorption and sedimentation are prominent, making it difficult to achieve efficient and stable sorting under complex feeding conditions.

[0004] Currently, mainstream industrial flotation equipment mainly includes two categories: mechanically agitated flotation machines and flotation columns. Both have inherent technical shortcomings in separation, with common problems including low energy utilization efficiency, poor mineralization conditions, and insufficient adaptability to wide particle size ranges. Conventional agitated flotation machines often employ a single-layer rotor-stator structure, with a limited agitation and aeration method. The turbulence intensity within the tank is limited, and energy dissipation is concentrated and unevenly distributed. They can only achieve simple slurry agitation and aeration dispersion, failing to enhance effective collisions between fine particles and air, resulting in insufficient mineralization and significant loss of fine particles. They also suffer from unstable flotation rates, high reagent consumption, and weak flow field control capabilities. While static separation equipment such as flotation columns slightly improves fine particle collision efficiency through pipe flow turbulence and swirling counter-current coupling, they suffer from low overall equipment integration, lengthy process flows, large footprint, high system energy consumption, and extremely poor adaptability to wide particle size slurries containing coarse components. Significant coarse particle settling and desorption problems exist, leaving room for improvement in overall separation versatility and engineering adaptability.

[0005] In summary, existing flotation equipment generally suffers from a series of technical defects, such as a simple turbulent structure, unreasonable energy dissipation layout, insufficient kinetic conditions for fine-grained mineralization, low recovery rate of valuable fine-grained minerals, poor adaptability to wide-particle-size materials, high energy consumption, and low equipment integration. These defects prevent the equipment from simultaneously meeting the dual production requirements of efficient and accurate recovery of fine-grained minerals and stable separation of complex wide-particle-size slurries in industrial settings, which severely restricts the efficient resource utilization of low-grade fine-grained disseminated minerals and tailings resources. Summary of the Invention

[0006] Purpose of the invention: In order to overcome the shortcomings of the existing technology, the present invention provides a multi-layer rotor-stator nested coupling flotation machine. Through the multi-layer rotor-stator nested coupling structure design, a multi-level gradient turbulent mineralization system is constructed, which enhances the efficiency of gas-particle collision, takes into account the differentiated separation needs of coarse and fine minerals, improves the flotation recovery rate and equipment integration, and reduces production energy consumption and land cost.

[0007] Technical Solution: To solve the above-mentioned technical problems, the present invention provides a multi-layer rotor-stator nested coupling flotation machine, comprising a cylinder, a stirring shaft, a baffle plate, a variable frequency motor, a controller, a concentrate trough, a feed inlet, a bottom air inlet, a concentrate outlet, and a tailings outlet. The variable frequency motor is fixed to the top of the cylinder, the stirring shaft is vertically installed inside the cylinder and its top end is connected to the variable frequency motor for transmission, and the controller is electrically connected to the variable frequency motor to regulate the stirring speed. The inner part of the cylinder is divided into a stirring zone and a separation zone. A multi-layer coupled rotor-stator assembly is nested inside the stirring zone. The rotor-stator assembly includes an inner rotor, an outer rotor, an inner stator, and an outer stator. The inner rotor and the outer rotor are coaxially fixedly connected to the stirring shaft. The baffle plate is fixed to the inner wall of the cylinder and located in the separation zone above the stirring zone. The feed inlet and the bottom air inlet are both connected to the stirring zone. The concentrate trough is located on the top side of the cylinder and connected to the separation zone. The concentrate outlet is located at the bottom of the concentrate trough, and the tailings outlet is located on the lower side wall of the cylinder.

[0008] Preferably, both the inner and outer stators adopt a square perforated plate structure. The inner stator is nested outside the inner rotor, and the outer stator is nested outside the outer rotor. The square perforated plate structure is used to uniformly disperse the slurry airflow, optimize the energy dissipation distribution in the tank, and enhance the mineralization effect in the stirring zone.

[0009] Preferably, the rotor-stator assembly is a radially nested arrangement structure, with the inner rotor and outer rotor coaxially fixed on the stirring shaft from top to bottom, and the inner stator, outer rotor, and outer stator nested sequentially from the inside to the outside to form a multi-level gradient stirring and aeration structure.

[0010] Preferably, the blades of the outer rotor are inclined along the radial direction, forming a 30° angle with the vertical radial direction, and the outer rotor rotates clockwise with the stirring shaft. The inclined blade structure forms a negative pressure circulation zone inside the stirring zone, optimizes the slurry flow trajectory, and realizes secondary circulation mineralization of the slurry.

[0011] Preferably, the inner rotor and the outer rotor are both fixed with a circular top plate. The circular top plate has several circulation holes evenly opened in the circumferential area near the stirring shaft. The circulation holes connect the upper part of the stirring zone with the core stirring zone, which is used to increase the circulation volume of the slurry in the cylinder and realize the multiple circulation separation of insufficiently mineralized particles.

[0012] Preferably, the baffles are evenly distributed along the circumference of the inner wall of the cylinder, and the baffles are arranged vertically with their lower ends extending to the top of the stirring zone. This is used to block the rotating flow field in the stirring zone, eliminate the slurry rotation disturbance in the separation zone, stabilize the foam layer, reduce the probability of coarse particle bubble desorption and settling, and reduce the phenomenon of tailings running off.

[0013] Preferably, the concentrate tank is equipped with a rinsing water spray structure, which is used to defoam the floating concentrate foam, so as to achieve stable discharge of concentrate and ensure uniform concentration of sorting products.

[0014] In this invention, the stirring zone is a high-energy turbulent mineralization zone, and the separation zone is a low-disturbance static sorting zone. Through the synergistic effect of multi-layer rotor-stator coupled stirring and baffle plate flow stabilization, high-energy mineralization and low-stability sorting are coupled in a single tank, taking into account the differentiated sorting requirements of efficient mineralization of fine particles and stable floating of coarse particles.

[0015] Beneficial effects: The multi-layer rotor-stator nested coupling flotation machine of the present invention has the following advantages:

[0016] (1) The multi-layer stirring rotor impeller is radially distributed, which optimizes the energy distribution of the stirring space. Compared with the traditional single rotor impeller, it can generate multiple slurry mineralization processes under the condition of constant stress.

[0017] (2) The dual stator dispersion design enables the slurry to undergo multiple flow state changes in the mixing area, such as dynamic-static-dynamic-static, thereby improving the particle-bubble collision efficiency.

[0018] (3) The design of the perforated rotor and stator can enhance the energy dissipation in the stirring zone and improve the efficiency of the mineralization reaction of the slurry.

[0019] (4) The slurry dispersion design and baffle plate can reduce the disturbance of the upper slurry of the flotation machine, reduce the probability of coarse particles falling off the mineralization bubbles, and reduce the tailings run-off.

[0020] (5) Due to the multiple mineralization reactions in a single cell, the yield of the slurry passing through once is increased, the flotation rate is faster than that of traditional flotation equipment, and the number of units and floor space required are reduced. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the present invention.

[0022] Figure 2 This is a cross-sectional view of the present invention.

[0023] Figure 3 This is a schematic diagram of the circulation hole.

[0024] Figure 4 This is a schematic diagram of the stirring cross-section.

[0025] Figure 5 This is a schematic diagram of the flow field in a flotation machine.

[0026] Figure 6 This is a schematic diagram of the flow field in the mixing zone.

[0027] Figure 7 This is the flotation recovery curve.

[0028] 1. Cylinder body; 2. Agitator shaft; 3. Baffle plate; 4. Variable frequency motor; 5. Controller; 6. Concentrate trough; 7. Feed inlet; 8. Inner rotor; 9. Outer rotor; 10. Inner stator; 11. Outer stator; 12. Separation zone; 13. Concentrate trough; 14. Concentrate inlet; 15. Tailings outlet; 16. Circular top plate; 17. Circulation hole Detailed Implementation

[0029] The invention will now be further described with reference to the accompanying drawings.

[0030] like Figures 1 to 7 As shown, this embodiment provides a multi-layer rotor-stator nested coupling flotation machine, which is a preferred embodiment of the present invention. The whole machine is a vertical single-cell continuous separation structure. The core includes a cylinder assembly, a power transmission component, a multi-layer rotor-stator coupled mineralization component, a flow field stabilization separation component, and a material feeding and discharging component. Each structure is precisely assembled and works in synergy. It can be adapted to the continuous flotation operation of mixed slurries with a wide particle size of less than 300μm and fine mineral particles of less than 74μm. The entire process is automated and speed-controlled. The specific structural assembly and working process are described in detail below.

[0031] The cylinder is a vertical cylindrical sealed tank, internally divided into a lower high-energy stirring and mineralization zone and an upper low-disturbance separation zone from top to bottom. A variable frequency motor is fixedly installed at the center of the top of the cylinder, and the output shaft of the variable frequency motor is vertically connected to and fixed to the stirring shaft. The stirring shaft is vertically suspended at the central axis of the cylinder and is the core component of the rotational power. The multi-layer rotor-stator coupled mineralization assembly is centrally assembled in the stirring zone below the stirring shaft and is the core improved structure of this invention. Specifically, it includes two parts: a rotating motion assembly and a fixed stationary assembly. The rotating motion assembly consists of an inner rotor, an outer rotor, and a circular top plate. The inner and outer rotors are coaxially and tightly fitted onto the stirring shaft from top to bottom, maintaining synchronous rotation with the stirring shaft without relative displacement. The inner rotor is located at the inner small diameter position, and the outer rotor is coaxially located at the outer large diameter position of the inner rotor. The radial spacing between the two rotors is uniform, forming a double-layer radial gradient stirring structure. A circular top plate is bolted together at the top of the two rotor layers. The center of the circular top plate is fixed with the stirring shaft by interference fit. Several circular circulation holes are evenly arranged in an annular array in the inner ring area of ​​the circular top plate near the stirring shaft. The circulation holes are connected vertically, connecting the upper cavity of the stirring zone with the core shearing area of ​​the rotor, so as to realize the internal circulation and return of the slurry.

[0032] The stator is a fixed, stationary component, comprising an inner stator and an outer stator, both of which are integral square perforated plate structures, fixed to the inner wall of the cylinder by a bracket, remaining stationary throughout the process. The inner stator is radially nested outside the inner rotor and inside the outer rotor, corresponding to the shearing region of the inner rotor, achieving primary static diversion and dispersion. The outer stator is nested outside the outer rotor, completely covering the rotation range of the outer rotor, achieving secondary static diversion and dispersion. This forms a dynamic-static coupled multi-stage mineralization structure of "dynamic shearing of the inner rotor—static dispersion of the inner stator—secondary dynamic shearing of the outer rotor—secondary static dispersion of the outer stator." Simultaneously, the blades of the outer rotor adopt an inclined arrangement structure, with a fixed 30° angle relative to the vertical radial direction. After assembly, the outer rotor rotates clockwise with the stirring shaft, creating a stable negative pressure suction area around the rotor, providing power for the internal circulation of the slurry.

[0033] Multiple vertical baffles are evenly fixed circumferentially on the inner wall of the cylinder and above the separation zone above the mixing zone. The inner side of the baffles is suspended, while the outer side is fixed to the cylinder wall. The lower end faces the top outlet of the mixing zone, which can directly block the circumferential swirling flow caused by the rotation of the mixing rotor, completely eliminating the slurry rotation disturbance in the separation zone and creating a stable static separation environment. When the equipment is working, the slurry, which has been pretreated with reagents and surface modified, is injected into the mixing zone under stable pressure through the feed port on the side wall of the cylinder. Air is evenly introduced into the core mixing area through the air inlet at the bottom of the cylinder. The controller adjusts the speed of the variable frequency motor in real time according to the slurry concentration and particle size parameters, driving the mixing shaft to rotate the double-layer rotor at high speed. The slurry and gas flow first enter the core shearing zone of the inner rotor. After high-speed shearing and turbulent mixing by the inner rotor, the slurry undergoes the first uniform dispersion and diversion through the square perforated plate of the inner stator, achieving initial gas particle mineralization. Subsequently, the slurry enters the transition zone between the inner stator and the outer rotor, where it is again subjected to strong shearing and turbulent disturbance by the outer rotor. The negative pressure field generated by the 30° tilted blades enhances the fluid disturbance, and the slurry undergoes secondary dispersion through the square perforated plate of the outer stator, achieving multi-stage continuous mineralization. This process continuously breaks large bubbles into fine, uniform bubbles, significantly increasing the probability of collision and adhesion between fine mineral particles and bubbles.

[0034] Incompletely mineralized high-density slurry and fine-grained tailings particles flow upwards through the circulation holes in the circular top plate of the rotor under negative pressure, then fall back to the core mixing zone of the rotor to participate in the next round of multi-stage shear mineralization cycle, completely solving the problems of fine-grained minerals flowing around the flow, insufficient mineralization, and resource loss. The highly stable and dense gas flocs formed after multiple dynamic-static coupling mineralization processes rise steadily into the upper separation zone after being uniformly diffused through the outer stator. Under the flow stabilization effect of the baffle plate, the turbulence intensity in the tank is greatly reduced, eliminating the phenomenon of coarse mineral bubble desorption and sedimentation, and the foam layer floats stably and orderly. The concentrate trough is integrated into the top side of the cylinder. The floating load mineral foam overflows into the concentrate trough. The flushing water spray structure built into the concentrate trough sprays evenly to defoam. The high-grade concentrate after defoaming is stably discharged from the concentrate outlet at the bottom of the concentrate trough. The tailings impurities after separation are evenly discharged from the tailings outlet on the lower side wall of the cylinder and sent to the next operation process. The whole flotation process is continuous, stable and controllable.

[0035] Working Principle: The flotation machine needle is designed to feed particles < 200μm. The pre-adjusted slurry and reagent mixture are injected through the flotation inlet. The equipment operates continuously, with a variable frequency motor driving the stirring shaft. The speed is adjusted by a controller. Slurry and gas flow into the stirring zone from the bottom, forming a high-energy dissipation zone during the shearing and dispersion process of multiple rotors and stators. During energy dissipation, the gas forms bubbles with increasingly smaller diameters. Simultaneously, the slurry and bubbles rapidly form mineralized bubbles under high-intensity stirring. After dispersing from the outer stator, the gas flocs float to the surface. Due to the stator angle design, a negative pressure zone is formed inside the stirring zone, allowing the slurry to return to the stirring zone through the circulation holes, while tailings flow out from the side of the flotation machine.

[0036] The mineralized bubbles and slurry gradually stabilize under the action of the baffle plate, the foam rises to the surface and forms a stable foam layer, which flows out to the concentrate tank. The concentrate tank is equipped with flushing water to defoam the concentrate and flow out, thus completing the entire flotation operation.

[0037] Workflow: The flotation process is continuous. The slurry in the mixing tank is initially mixed with frother and collector, and enters the flotation machine cylinder 1 through the flotation and feed inlet 7. At the same time, gas is introduced from the bottom. The speed is adjusted by the controller 5, and the variable frequency motor 4 drives the stirring shaft 2 to rotate, so that the slurry and air can fully react in the mixing zone. Under the action of the multi-layer stirring rotors 8 and 9 and stators 10 and 11, the bubbles are mineralized multiple times and dispersed to the separation zone 12. The rotation is eliminated by the action of the baffle plate 3, and the bubbles rise and flow into the concentrate tank 13 and are discharged from the concentrate outlet 14. Due to the inclination of the outer rotor 9, a negative pressure is generated in the mixing zone. The heavier slurry returns to the mixing zone through the circulation hole 17 to participate in the separation again. The tailings are discharged from the tailings outlet 15 at the bottom of the side wall of the flotation machine to the next process.

[0038] To directly verify the technical advantages of the multi-layer coupling structure of this invention, a 1L laboratory prototype was fabricated for flow field numerical simulation and flotation control experiments. The prototype was assembled strictly according to the aforementioned multi-layer rotor-stator nested structure, retaining the core structures of a double-layer rotor, a double-layer square perforated stator, 30° inclined blades, top circulation holes, and circumferential baffles. Flow field numerical simulation results show that at a low speed of 1200 rpm, the average flow velocity in the stirring zone of this invention can reach 3.8 m / s, and the turbulent kinetic energy in the stirring zone can reach 0.5 m² / s². The fluid shear, turbulent dissipation, and gas-particle hybrid dynamics performance are significantly better than the flow field parameters of the traditional XFD-1L single-rotor stator flotation machine at a high speed of 1800 rpm, achieving stronger mineralization kinetics with lower energy consumption.

[0039] Flotation tests were conducted using anthracite coal with an ash content of 26%. The feed particle size was controlled below 300 μm, the pulp concentration was 8-12%, and diesel oil and 2-octanol were used as reagents. The feed rate was 1 L, the aeration rate was 2 L / min, and the flotation time was 300 s. The test results showed that the cumulative recovery rate of coal slime using the flotation machine of this invention reached 93.5%, and the ash content of the clean coal was as low as 11.3%. Under the same operating conditions, the recovery rate of the traditional XFD type flotation machine at a speed of 1800 rpm was only 86.9%, and the ash content of the clean coal was 11.8%. Figures 4-7 As shown in the comparison, the present invention can significantly improve the mineral flotation recovery rate, optimize the concentrate quality, reduce energy consumption and reagent consumption, and its separation performance is far superior to that of traditional equipment.

[0040] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A multi-layer rotor-stator nested flotation machine, comprising a cylinder, a stirring shaft, a baffle plate, a variable frequency motor, a controller, a concentrate tank, a feed inlet, a bottom air inlet, a concentrate outlet, and a tailings outlet, wherein the variable frequency motor is fixed to the top of the cylinder, the stirring shaft is vertically installed inside the cylinder and its top end is connected to the variable frequency motor for transmission, and the controller is electrically connected to the variable frequency motor to regulate the stirring speed, characterized in that: The inner part of the cylinder is divided into a stirring zone and a separation zone. The stirring zone is nested with a multi-layered coupled rotor-stator assembly, which includes an inner rotor, an outer rotor, an inner stator, and an outer stator. The inner and outer rotors are coaxially fixedly connected to the stirring shaft. The baffle plate is fixed to the inner wall of the cylinder and located in the separation zone above the stirring zone. The feed inlet and the bottom air inlet are both connected to the stirring zone. The concentrate trough is located on the top side of the cylinder and is connected to the separation zone. The concentrate outlet is located at the bottom of the concentrate trough, and the tailings outlet is located on the lower side wall of the cylinder.

2. A multi-layer rotor-stator nested coupled flotation machine according to claim 1, characterized in that, Both the inner and outer stators adopt a square perforated plate structure. The inner stator is nested outside the inner rotor, and the outer stator is nested outside the outer rotor.

3. A multi-layer rotor-stator nested coupled flotation machine according to claim 1, characterized in that, The rotor-stator assembly is a radially nested arrangement structure. The inner rotor and outer rotor are coaxially fixed on the stirring shaft from top to bottom. The inner stator, outer rotor, and outer stator are nested sequentially from the inside to the outside to form a multi-level gradient stirring and aeration structure.

4. A multi-layer rotor-stator nested coupled flotation machine according to claim 1, characterized in that, The blades of the outer rotor are inclined along the radial direction, forming a 30° angle with the vertical radial direction, and the outer rotor rotates clockwise with the stirring shaft.

5. A multi-layer rotor-stator nested coupled flotation machine according to claim 1, characterized in that, The inner rotor and the outer rotor are both fixed with a circular top plate. The circular top plate has several circulation holes evenly opened in the circumferential area near the stirring shaft. The circulation holes connect the upper part of the stirring zone with the core stirring zone.

6. A multi-layer rotor-stator nested coupled flotation machine according to claim 1, characterized in that, The baffles are evenly distributed along the circumference of the inner wall of the cylinder, and the baffles are arranged vertically with their lower ends extending to the top of the stirring zone.

7. A multi-layer rotor-stator nested coupled flotation machine according to claim 1, characterized in that, The concentrate tank is equipped with a rinsing water spray structure.

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