Non-ionic flocculant synergistic window red mud sedimentation method, application and device

Abstract

This invention discloses a method, application, and apparatus for red mud sedimentation with a synergistic window of nonionic flocculant. The method includes: step S100: providing a suspension slurry containing red mud particles to be separated, the slurry having a predetermined combination of physical properties; step S200: quantitatively supplying a nonionic polymeric flocculant to the slurry provided in step S100 and performing flocculation and sedimentation to form a solid-liquid separation system comprising an upper clear liquid and a lower sediment layer; step S300: during the flocculation and sedimentation operation, maintaining the combination of physical properties within a synergistic operating window through closed-loop control, wherein the combination of physical properties includes the mass percentage concentration of solid phase, the proportion of fine particles, and the clay mineral content in the slurry. This red mud sedimentation method, application, and apparatus can achieve closed-loop matching between the supply of nonionic polymeric flocculant and the solid-liquid separation efficiency under conditions of fluctuation in the combination of physical properties of the slurry.

Description

Technical Field

[0001] This invention relates to hydrometallurgical solid-liquid separation technology in alumina production, and particularly to a method, application, and apparatus for the synergistic settling of red mud with nonionic flocculants. Background Technology

[0002] In the hydrometallurgical process of alumina, the Bayer process leaching produces a suspension slurry containing red mud particles, which requires flocculation and sedimentation to achieve solid-liquid separation between the red mud and the sodium aluminate solution. The efficiency of this separation process directly affects the stability of subsequent decomposition processes, the quality of the alumina product, and the system's alkali and energy consumption indicators. The sedimentation tank, operating in the industrial field, is the core separation equipment. The solids concentration, particle size distribution, and clay mineral content of the feed slurry continuously fluctuate with changes in bauxite source and leaching conditions. These changes in physical properties directly alter the bridging adsorption efficiency of the flocculant and the drainage and consolidation behavior of the flocs.

[0003] In existing red mud settling and separation processes, flocculant selection mainly focuses on anionic polyacrylamide, adapting to slurry conditions by changing the molecular weight and ionicity of the agent. However, when the mass percentage concentration of solids in the slurry deviates from the empirical range, the proportion of fine particles exceeds the conventional range, or the clay mineral content rises to a high level, the ionicity control of a single agent is insufficient to comprehensively account for the behavior of flocs throughout the free settling, transitional compression, and final consolidation stages. On-site operators typically make stepwise adjustments to the flocculant dosage based on offline sampling and testing results, lagging behind real-time changes in slurry properties.

[0004] Current parameter adjustments in red mud settling processes largely rely on single-variable empirical control, lacking synergistic regulation methods based on multi-factor correlations between solid concentration, particle size distribution, and flocculant supply rate. When the proportion of fine particles in the slurry increases, the tortuosity of the floc drainage channels increases, limiting the sediment compression rate and easily leading to abnormal concentration gradients at the bottom discharge end of the settling tank. When the clay mineral content increases, the competitive adsorption of flocculant molecular chains by clay particles intensifies, increasing the turbidity of the supernatant under conventional dosing strategies, increasing the amount of alkali adsorbed in the bottom flow, and intensifying the load on the countercurrent washing section.

[0005] Therefore, it is necessary to design a non-ionic flocculant synergistic window red mud sedimentation method, application and device, so as to achieve closed-loop matching between the supply of non-ionic polymeric flocculants and solid-liquid separation efficiency under the working conditions of fluctuating physical properties of slurry. Summary of the Invention

[0006] To address the above issues and overcome the shortcomings of existing technologies, this invention provides a method, application, and apparatus for red mud sedimentation with a synergistic window of nonionic flocculants. This method, application, and apparatus can achieve a closed-loop matching between the supply of nonionic polymeric flocculants and the solid-liquid separation efficiency under conditions of fluctuating physical properties of the slurry.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A nonionic flocculant synergistic window red mud sedimentation method includes the following steps:

[0009] Step S100: Provide a suspension slurry containing red mud particles to be separated, the slurry having a predetermined combination of physical properties;

[0010] Step S200: A non-ionic polymeric flocculant is quantitatively supplied to the slurry provided in step S100, and flocculation and sedimentation are performed to form a solid-liquid separation system comprising an upper clear liquid and a lower sediment layer.

[0011] Step S300: During the flocculation and sedimentation operation, the combination of physical properties is maintained within a collaborative operation window through closed-loop control, wherein the combination of physical properties includes the mass percentage concentration of solids in the slurry, the proportion of fine particles, and the clay mineral content.

[0012] Furthermore, the nonionic polymeric flocculant mentioned in step S200 is nonionic polyacrylamide.

[0013] Furthermore, the nonionic polyacrylamide has a molecular weight range of 14 million to 16 million.

[0014] Furthermore, the collaborative operation window in step S300 specifically includes: the mass percentage concentration of the solid phase is 8% to 12%; the fine particles, on a dry basis, have a particle size of less than 75 micrometers accounting for 15% to 25%; and the clay mineral content, on a dry basis, is 0.5% to 2.0%.

[0015] Furthermore, the solid phase has a mass percentage concentration of 10%, the particles with a diameter of less than 75 micrometers account for 20%, and the clay mineral content is 1.5%.

[0016] Furthermore, the clay mineral is kaolinite.

[0017] Furthermore, the suspension slurry containing red mud particles to be separated in step S100 is a diluted slurry obtained by treating bauxite through a dual-flow leaching process.

[0018] Furthermore, it also includes an intelligent control step that runs parallel to step S300: Online detection units deployed along the process flow collect measured values ​​of process parameters such as the solid content percentage, fine particle size, and clay mineral content of the slurry at a preset frequency; these measured values ​​are used as input vectors and fed into a pre-built multi-factor correlation model, which calculates and outputs adjustment commands for the supply rate of the non-ionic polymeric flocculant and the underflow discharge rate of the settling tank; these adjustment commands are transmitted via fieldbus to the frequency converter of the flocculant metering pump and the underflow discharge valve actuator for execution, so that the combination of physical properties is dynamically maintained within the collaborative operation window.

[0019] Furthermore, the Bayer process red mud sedimentation and separation method for processing kaolinite-type bauxite uses the suspension slurry containing red mud particles obtained after the Bayer process leaching of kaolinite-type bauxite as the object to be separated, and performs the aforementioned non-ionic flocculant synergistic window red mud sedimentation method.

[0020] Furthermore, a nonionic flocculant synergistic window red mud settling device is used to implement the aforementioned nonionic flocculant synergistic window red mud settling method. The device includes a settling tank, a flocculant metering pump, an online detection unit, and a controller arranged sequentially along the process flow. The online detection unit is configured to collect and send measured values ​​of process parameters such as the solid content percentage, fine particle ratio, and clay mineral content of the slurry to the controller at a preset frequency. The controller internally integrates the multi-factor correlation model and is configured to receive the measured values ​​of the process parameters, run the multi-factor correlation model to generate adjustment commands, and send the adjustment commands via fieldbus to the frequency converter driver of the flocculant metering pump and the valve actuator at the bottom flow discharge end of the settling tank, respectively or simultaneously, to dynamically regulate the supply rate of the nonionic polymeric flocculant and the bottom flow discharge rate of the settling tank.

[0021] This invention has at least the following advantages or beneficial effects:

[0022] This invention employs a predefined combination of physical properties and a quantitative supply of nonionic polymeric flocculants, establishing a correspondence between flocculant type and the initial state of the slurry. This reduces the probability of loose floc structures caused by mismatched floc types. Furthermore, it utilizes a closed-loop control mechanism during flocculation and sedimentation to regulate the percentage concentration of solids, the proportion of fine particles, and the clay mineral content. This ensures that the aforementioned physical property combinations consistently converge within a synergistic operating window, suppressing the impact of feed fluctuations on sedimentation rate and consolidation degree. Overall, this invention achieves a closed-loop match between nonionic polymeric flocculant supply and solid-liquid separation efficiency even under fluctuating slurry physical property combinations, contributing to increased solids content at the bottom of the sedimentation tank and reduced overflow suspended solids content.

[0023] In this invention, the nonionic polymeric flocculant mentioned in step S200 is selected as nonionic polyacrylamide. By utilizing the adsorption configuration formed by the molecular chain segments of this type of flocculant on the surface of red mud particles through hydrogen bonds and van der Waals forces, particle bridging can be completed without introducing additional ionic charges, which helps to maintain the continuity of the floc drainage channels under conditions with high clay mineral content.

[0024] The present invention controls the molecular weight range of the nonionic polyacrylamide to 14 million to 16 million, so that the extension radius of a single polymer molecular chain segment in the liquid phase matches the spacing between fine-grained red mud particles. This can provide sufficient bridging site density under low reagent consumption conditions, which is beneficial to shortening the duration of the free settling phase.

[0025] The present invention further limits the collaborative operation window mentioned in step S300 to 8% to 12% of solid mass concentration, 15% to 25% of fine particles with a particle size of less than 75 micrometers, and 0.5% to 2.0% of clay mineral content. This makes the value ranges of the three physical property parameters form mutually restrictive boundary conditions, which can avoid the phenomenon that the flocs will experience a sudden drop in drainage rate or an abnormal increase in the porosity of the sedimentary layer in the transition compression section after a single parameter deviates from the window.

[0026] The present invention sets the solid phase mass percentage concentration to 10%, the proportion of particles with a diameter of less than 75 micrometers to 20%, and the clay mineral content to 1.5%. This combination of values ​​is located in the optimal sub-interval within the collaborative operation window, which can make the rate distribution of each stage of flocculation and sedimentation tend to be balanced. It is suitable for industrial operation scenarios with high requirements for the treatment throughput per unit area of ​​the sedimentation tank.

[0027] This invention limits the clay mineral to kaolinite. Taking advantage of the characteristic that kaolinite is easily dispersed into flaky particles in high-alkali sodium aluminate solution, the boundary conditions of the cooperative operation window are matched with the surface charge behavior of this type of clay mineral, which helps to maintain the transmittance of the supernatant in the red mud separation operation of kaolinite-type bauxite.

[0028] The present invention limits the suspension slurry containing red mud particles to be separated in step S100 to a diluted slurry obtained by bauxite leaching process using a dual-flow leaching method. By utilizing the pre-process control effect of dual-flow leaching on the surface charge distribution and particle size distribution of red mud particles, the slurry has an initial physical property benchmark that is compatible with the cooperative operation window before entering the settling operation, which can reduce the adjustment frequency of closed-loop control in step S300.

[0029] This invention adds an intelligent control step that is integrated in parallel with step S300. The online detection unit collects the measured values ​​of process parameters at a preset frequency and feeds the measured values ​​of process parameters into a multi-factor correlation model to generate adjustment instructions for the flocculant supply rate and the discharge rate of the sedimentation tank bottom flow. This allows the combination of physical properties of the slurry to be dynamically maintained within the collaborative operation window during continuous production, which can reduce the overshoot caused by the lag of manual sampling and help reduce the batch-to-batch fluctuation of the amount of alkali adsorbed in the bottom flow.

[0030] This invention provides a processing path for using a suspension slurry containing red mud particles obtained from the Bayer process of kaolinite-type bauxite as the object to be separated. The adaptation relationship between the ore source characteristics and the collaborative operation window is solidified as a process flow selection condition, which can reduce the number of trial and error adjustments of process parameters when switching ore sources.

[0031] This invention provides a sedimentation device configuration for implementing the aforementioned intelligent control steps. Its online detection unit is deployed along the process flow and forms a data link with the controller. The controller internally stores a multi-factor correlation model and connects to the variable frequency drive of the flocculant metering pump and the valve actuator at the bottom flow discharge end of the sedimentation tank via a fieldbus. This enables the acquisition of measured values ​​of process parameters, model calculation, and execution of adjustment commands to form a closed loop, providing a hardware-level collaborative control foundation for the continuous operation of the sedimentation tank. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 Flowchart of red mud sedimentation method with synergistic window of nonionic flocculant;

[0034] Figure 2 Curves showing the height variation of red mud sedimentary layers with different PAM flocculants added;

[0035] Figure 3The average settling rate curves of red mud with different PAM flocculants and the average settling rates at 10 min, 30 min and final consolidation stability are shown.

[0036] Figure 4 Curves showing the variation in height of red mud sedimentary layers with different slurry concentrations;

[0037] Figure 5 The average settling rate curves of red mud with different slurry concentrations and the average settling rates at 10 min, 30 min, and 10 min after final consolidation and stabilization.

[0038] Figure 6 Curves showing the height variation of red mud sedimentary layers with different particle size distributions;

[0039] Figure 7 The average settling rate curves of red mud with different particle size distributions and the average settling rates at 10 min, 30 min and 10 min after final consolidation and stabilization.

[0040] Figure 8 The height variation curves of red mud sedimentary layers with different clay mineral contents are shown.

[0041] Figure 9 The height variation curves of red mud sedimentary layers with different clay mineral contents are shown.

[0042] Figure 10 The curves of the average settling rate of red mud from the orthogonal experiment are shown, along with the average settling rates at 10 min, 30 min, and 10 min after final consolidation and stabilization.

[0043] Figure 11 The curves showing the variation in the height of the red mud sediment layer in the orthogonal experiment;

[0044] Figure 12 This is a graph showing the relationship between key indicators of red mud settling-consolidation performance in orthogonal experiments. Detailed Implementation

[0045] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0046] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0047] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0048] In this invention, terms such as "upper," "lower," "left," "right," "front," "back," "vertical," "horizontal," "side," and "bottom" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are only used to facilitate the description of the structural relationships of the various components or elements of this invention and do not specifically refer to any part or element in this invention. They should not be construed as limitations on this invention.

[0049] In this invention, terms such as "fixed," "connected," and "linked" should be interpreted broadly, indicating that the connection can be fixed, integral, or detachable; it can be a direct connection or an indirect connection through an intermediate medium. For researchers or technicians in the field, the specific meaning of the above terms in this invention can be determined according to the specific circumstances, and they should not be construed as limitations on this invention.

[0050] The embodiments of the present invention will be described in detail below.

[0051] This invention discloses a method, application, and apparatus for the synergistic deposition of red mud using a nonionic flocculant.

[0052] The nonionic flocculant-assisted red mud sedimentation method mainly includes the following steps:

[0053] Step S100: Provide a suspension slurry containing red mud particles to be separated, the slurry having a predetermined combination of physical properties;

[0054] Step S200: A non-ionic polymeric flocculant is quantitatively supplied to the slurry provided in step S100, and flocculation and sedimentation are performed to form a solid-liquid separation system comprising an upper clear liquid and a lower sediment layer.

[0055] Step S300: During the flocculation and sedimentation operation, the combination of physical properties is maintained within a collaborative operation window through closed-loop control, wherein the combination of physical properties includes the mass percentage concentration of solids in the slurry, the proportion of fine particles, and the clay mineral content.

[0056] In this embodiment, the suspension slurry containing red mud particles to be separated originates from the Bayer leaching process in the alumina hydrometallurgical process. The route for obtaining this suspension slurry is as follows:

[0057] Kaolinite-type bauxite is selected, crushed, ground, and pre-treated for impurity removal, and then fed into a dual-flow leaching system. The alumina component in the bauxite is leached under predetermined leaching temperature, caustic alkali concentration, and stirring intensity. The resulting leaching slurry is diluted to form the suspension slurry containing red mud particles to be separated as described in step S100 of this method.

[0058] The crushing process can be a two-stage crushing circuit consisting of a jaw crusher and a cone crusher; the grinding process can be a closed-circuit grinding circuit consisting of a ball mill or rod mill and a hydrocyclone; and the pre-removal process can include at least one of magnetic separation for iron removal and flotation for silicon removal.

[0059] In other embodiments, the bauxite may also be monohydrate gibbsite or trihydrate gibbsite, which is processed by the corresponding Bayer leaching process to obtain the suspension slurry.

[0060] The suspension slurry has a predetermined combination of physical properties, which includes three parameters: the mass percentage concentration of the solid phase, the proportion of fine particles, and the clay mineral content.

[0061] Among them, the mass percentage concentration of solids refers to the percentage of red mud solids in the total mass of the suspended slurry. Its function is to characterize the solid flux level at the feed end of the settling tank. The value of this parameter can be controlled online by the dilution water regulating valve installed on the feed pipeline of the settling tank.

[0062] The proportion of fine particles refers to the percentage of particles with a diameter of less than 75 micrometers in the solid phase of red mud, based on dry weight. Its function is to characterize the proportion of fine particles in the slurry that are easily encapsulated by the flocculant bridge.

[0063] Clay mineral content refers to the percentage of clay minerals in the solid phase of red mud on a dry basis. It is used to characterize the amount of colloidal particles in the slurry that may compete with flocculants for adsorption or block the drainage channels of flocs.

[0064] In this embodiment, the nonionic polymeric flocculant mentioned in step S200 is nonionic polyacrylamide. This nonionic polyacrylamide is prepared by free radical polymerization of acrylamide monomer under the action of an initiator. Its molecular chain segments do not contain ionizable ionic groups and are electrically neutral in the sodium aluminate solution system.

[0065] Because nonionic polyacrylamide is used, its molecular chain segments form an adsorption configuration on the surface of red mud particles through hydrogen bonds and van der Waals forces. This configuration can complete the particle bridging without introducing additional ionic charges, which helps to maintain the continuity of the floc drainage channels under conditions with high clay mineral content.

[0066] In step S200, the nonionic polyacrylamide is quantitatively supplied to the suspension slurry provided in step S100 by a flocculant metering pump. The supply method is multi-point injection along the radial cross-section of the settling tank feed pipe. In this embodiment, there are 4 injection points, which are evenly spaced along the circumference of the pipe. Each injection point is equipped with a one-way valve to prevent slurry backflow. In other embodiments, the number of injection points can also be 2, 3 or 6 to achieve rapid and uniform mixing of flocculant and slurry.

[0067] After injection, the flocculant molecular chain segments form an adsorption configuration on the surface of red mud particles through hydrogen bonds and van der Waals forces, bridging the dispersed red mud particles into flocs with a three-dimensional network structure, and then performing flocculation and sedimentation operations in the settling tank.

[0068] The settling process consists of three consecutive stages: a free settling stage, a transitional compression stage, and a final consolidation stage. The duration of each stage and the rate of interface descent depend on the matching relationship between the combination of physical properties and the flocculant supply parameters.

[0069] After a complete flocculation and sedimentation process, a solid-liquid separation system consisting of an upper clear liquid and a lower sediment layer is formed in the sedimentation tank. The upper clear liquid is a pure sodium aluminate solution, which is discharged through the overflow weir and enters the subsequent decomposition process. The lower sediment layer is a red mud slurry with high solids content, which is led out through the underflow discharge end and sent to the countercurrent washing section for further recovery of adsorbed alkali.

[0070] In this embodiment, the molecular weight of the nonionic polyacrylamide ranges from 14 million to 16 million. Controlling the molecular weight between 14 million and 16 million allows the extension radius of individual polymer molecular chain segments in the liquid phase to match the average spacing of fine particles in the red mud slurry, providing sufficient bridging site density with low reagent consumption.

[0071] Preferably, the nonionic polyacrylamide has a molecular weight of 15 million and a consumption of 200 g / ton of dry red mud. In other embodiments, the molecular weight may also be 14 million, 14.5 million, 15.5 million, or 16 million, and the consumption may be adjusted between 150 g / ton and 250 g / ton depending on the solid concentration of the incoming slurry.

[0072] In the specific preparation process, the nonionic polyacrylamide is first prepared into an aqueous solution with a mass percentage concentration of 0.05% to 0.15% using an automatic dissolving device, and then injected into the slurry via a flocculant metering pump.

[0073] In this embodiment, the collaborative operation window in step S300 is specifically defined as follows: the mass percentage concentration of the solid phase is 8% to 12%, the proportion of particles with a diameter of less than 75 micrometers in the fine particles is 15% to 25%, and the clay mineral content is 0.5% to 2.0% on a dry basis.

[0074] The function of the collaborative operation window is to define the upper and lower boundaries of allowable fluctuations for the three parameters in the combination of physical properties, so that when the measured values ​​of the three parameters are simultaneously within their respective boundaries, the flocculation bridging efficiency, floc drainage rate and sedimentation compression rate of nonionic polyacrylamide can form a mutually matched process state, thereby maintaining the final average settling rate of red mud sedimentation separation above the preset process index.

[0075] By setting mutually restrictive boundary conditions based on the value ranges of the three physical property parameters, it is possible to avoid the phenomenon of a sudden drop in drainage rate or an abnormal increase in porosity of the sedimentary layer in the transition compression section when a single parameter deviates from the window.

[0076] When any physical property parameter of the incoming slurry drifts outside the collaborative operation window, the closed-loop control in step S300 initiates corresponding adjustment actions, including adjusting the flocculant supply rate and adjusting the bottom flow discharge rate of the settling tank, in order to pull the drifting parameter back into the window.

[0077] In this embodiment, the parameter combination within the collaborative work window is further preferably:

[0078] The solid phase has a mass percentage concentration of 10%, the particles with a diameter of less than 75 micrometers account for 20%, and the clay mineral content is 1.5%.

[0079] Because this combination of values ​​falls within the optimal sub-interval of the collaborative operation window, it can make the rate distribution of each stage of flocculation and sedimentation tend to be balanced, making it suitable for industrial operation scenarios with high requirements for the throughput per unit area of ​​the sedimentation tank. Experimental verification shows that under this optimized parameter combination, combined with non-ionic polyacrylamide with a molecular weight of 15 million, and with a consumption of 200 g / ton of dry red mud, the average sedimentation rate in the final consolidation stage reaches 6.73 mm / min.

[0080] like Figure 1 As shown, the overall process of this method includes: Step S100: providing a suspension slurry containing red mud particles to be separated, the slurry having a predetermined combination of physical properties;

[0081] Step S200: A non-ionic polymeric flocculant is quantitatively supplied to the slurry provided in step S100, and flocculation and sedimentation are performed to form a solid-liquid separation system comprising an upper clear liquid and a lower sediment layer.

[0082] Step S300: During the flocculation and sedimentation operation, the combination of physical properties is maintained within a collaborative operation window through closed-loop control, wherein the combination of physical properties includes the mass percentage concentration of solids in the slurry, the proportion of fine particles, and the clay mineral content.

[0083] like Figure 2 As shown, under the same conditions of slurry concentration, particle size distribution and clay mineral content, nonionic polyacrylamide, anionic polyacrylamide and cationic polyacrylamide were added respectively, and the change in water-mud interface height was recorded from 0 to 300 minutes.

[0084] The experimental group with added nonionic polyacrylamide showed a slightly lower interface descent rate in the free settling stage compared to the anionic polyacrylamide group. However, in the transition compression stage and the final consolidation stage, the sedimentation layer height continued to decrease and the final value was lower than that of the other two groups, indicating that nonionic polyacrylamide has advantages in accelerating red mud consolidation and improving sedimentation layer density.

[0085] like Figure 3 As shown, the average settling rates at 10 minutes, 30 minutes, and the final consolidation and stabilization stage were statistically analyzed. The average settling rate of the nonionic polyacrylamide group was higher than that of the anionic polyacrylamide group and the cationic polyacrylamide group in the final consolidation and stabilization stage, which further confirms its role in promoting deep dehydration and consolidation of red mud.

[0086] In this embodiment, the clay mineral is kaolinite. By limiting the clay mineral to kaolinite, and considering the characteristic that kaolinite easily disperses into flaky colloidal particles in a high-alkali sodium aluminate solution, the boundary conditions of the cooperative working window are matched with the surface charge behavior of this type of clay mineral, which helps to maintain the transmittance of the supernatant in the red mud separation operation of kaolinite-type bauxite.

[0087] Kaolinite is easily dispersed into flaky particles in a high-alkali sodium aluminate solution. Its surface has a different charge distribution characteristics than red mud particles, which will competitively adsorb flocculant molecular chain segments and form a hydrophobic film on the surface of the floc, hindering the discharge of pore water inside the floc.

[0088] In other embodiments, the clay mineral may also be a layered silicate mineral such as montmorillonite, illite, or chlorite, and the boundary conditions of the cooperative operation window may be adjusted accordingly based on the surface charge density and dispersion characteristics of the clay mineral.

[0089] In this embodiment, the suspension slurry containing red mud particles to be separated in step S100 is a diluted slurry obtained by treating bauxite through a dual-flow leaching process.

[0090] Because a diluted slurry obtained by treating bauxite with a dual-flow leaching process is used, the dual-flow leaching process is used to pre-control the surface charge distribution and particle size distribution of red mud particles. This allows the slurry to have an initial physical property benchmark that is compatible with the collaborative operation window before entering the settling operation, which can reduce the adjustment frequency of closed-loop control in step S300.

[0091] The dual-flow leaching process can pre-regulate the surface charge distribution and particle size distribution of red mud particles by controlling the temperature, caustic alkali concentration and residence time in stages during the leaching process. This makes the initial physical properties of the red mud particles after leaching closer to the central region of the collaborative operation window, thereby reducing the frequency and magnitude of closed-loop regulation in step S300.

[0092] In other embodiments, the suspension slurry can also be produced by a single-flow leaching process, but in this case, the initial adjustment amount of the closed-loop control in step S300 needs to be increased accordingly.

[0093] like Figure 4 As shown, five groups of red mud slurries with solid content of 10%, 15%, 20%, 25% and 30% were set up. Nonionic polyacrylamide with a molecular weight of 15 million was used and the consumption was 200 g / ton of dry red mud. The change in sediment height was recorded from 0 to 180 minutes.

[0094] When the mass percentage concentration of solids is 10%, the sedimentation layer height decreases at the fastest rate and reaches the lowest value. As the concentration increases, the interparticle interference sedimentation effect intensifies, the pore compression of flocs is hindered, and the sedimentation layer height decreases at each level.

[0095] like Figure 5 As shown, the average settling rate of the 10% concentration group was higher than that of other concentration groups at 10 minutes, 30 minutes and the final consolidation and stabilization stage. The advantage of average settling rate in the final consolidation and stabilization stage was the most prominent, indicating that a lower solids mass percentage concentration is beneficial to the full drainage and consolidation of nonionic polyacrylamide flocs.

[0096] In other embodiments, the mass percentage concentration of the solid phase can also be adjusted online between 8% and 12% according to the treatment throughput requirements of the settling tank. When the treatment throughput requirement increases, the concentration can be appropriately shifted towards the upper limit of 12%, and the flocculant supply rate can be increased accordingly to compensate for the impact of interference with settling.

[0097] like Figure 6As shown, five groups of red mud samples were prepared with fine particles of less than 75 micrometers, accounting for 20%, 40%, 60%, 80%, and 100% respectively. Nonionic polyacrylamide with a solid content of 20% and a molecular weight of 15 million was used uniformly, and the consumption was 200 grams per ton of dry red mud. A 300-minute sedimentation-consolidation test was carried out.

[0098] When the proportion of fine particles is 20%, the natural gravity settling of coarse particles and the flocculation bridging settling of fine particles form a synergistic effect, resulting in the most sufficient reduction in the height of the sedimentary layer.

[0099] like Figure 7 As shown, the group with 20% fine particles had the highest average settling rate in the final consolidation and stabilization stage, indicating that the drainage channel morphology of the flocs was optimal under this particle size distribution.

[0100] In other embodiments, the proportion of particles with a diameter of less than 75 micrometers can also be adjusted between 15% and 25% according to the particle size distribution of the grinding circuit output. By controlling the grinding time or the grinding media ratio, the particle size distribution of the red mud particles entering the settling tank can be made to fall within the collaborative operation window.

[0101] like Figure 8 and Figure 9 As shown, using kaolinite as the exogenous clay, five groups of red mud samples with clay mineral contents of 1.5%, 5%, 10%, 15% and 20% were set up. Nonionic polyacrylamide with a solid mass percentage concentration of 20% and a molecular weight of 15 million was used uniformly with a consumption of 200 g / ton of dry red mud, and a sedimentation-consolidation test lasting up to 660 minutes was carried out.

[0102] When the clay mineral content is 1.5%, the sedimentary layer height decreases the fastest and reaches the lowest final value, with the shortest consolidation completion time. As the clay mineral content increases, the hydrophobic film formed by kaolinite particles on the surface of red mud particles gradually thickens, exacerbating the blockage effect of floc drainage channels and inhibiting both the sedimentary layer height decrease rate and the final compression degree. In this embodiment, the upper limit threshold for clay mineral content is set at 2.0%. When the clay mineral content of the incoming slurry exceeds this threshold, the system triggers an early warning and initiates ore blending adjustment or pre-desliming treatment to avoid the chain reaction problems of slow settling and increased alkali adsorption in the underflow under high clay conditions.

[0103] like Figure 10 , Figure 11 and Figure 12 As shown, a four-factor, three-level orthogonal experiment was used to conduct a multi-factor coupled analysis of the type of nonionic flocculant, the percentage concentration of solid matter, the proportion of fine particles, and the clay mineral content. Table 1 shows the factor level arrangement of the four-factor, three-level orthogonal experiment; Table 2 shows the results of the orthogonal experiment.

[0104] Table 1. Factor Level Arrangement for a Four-Factor, Three-Level Orthogonal Experiment

[0105]

[0106] Table 2. Results of Orthogonal Experiments

[0107]

[0108] The experiment used the final average settling rate as the primary evaluation index, supplemented by auxiliary indicators such as the 10-minute average settling rate, the 30-minute average settling rate, the final height of the sedimentary layer, and the total consolidation time. Range analysis and variance analysis were used to determine the order of influence of each factor on the red mud settling performance, and factor-index trend diagrams and interaction maps were plotted. The "factor-structure-performance" correspondence data established by the orthogonal experimental results constitutes the core data foundation of the multi-factor correlation model described in this method. The multi-factor correlation model is stored internally in the controller. Its input vector consists of the measured values ​​of process parameters such as solid mass percentage concentration, fine particle proportion, and clay mineral content. The output vector consists of the target values ​​of the non-ionic polymeric flocculant supply rate and the target value of the bottom flow discharge rate of the settling tank. This multi-factor correlation model can be constructed using one of the following: a multiple linear regression model, a response surface model, or an artificial neural network model. Its training samples are derived from the orthogonal experimental data and supplementary single-factor validation experimental data.

[0109] In this embodiment, the nonionic flocculant synergistic window red mud sedimentation method further includes an intelligent control step that is integrated in parallel with step S300.

[0110] By adding this intelligent control step, the online detection unit collects the measured values ​​of process parameters at a preset frequency and feeds the measured values ​​of process parameters into a multi-factor correlation model to generate adjustment instructions for the flocculant supply rate and the discharge rate of the sedimentation tank bottom flow. This allows the combination of physical properties of the slurry to be dynamically maintained within the collaborative operation window during continuous production, which can reduce the overshoot caused by the lag of manual sampling and help reduce the batch-to-batch fluctuation of the amount of alkali adsorbed in the bottom flow.

[0111] In this intelligent control step, online detection units deployed along the process flow collect measured values ​​of process parameters such as the mass percentage concentration of solid phase, the proportion of fine particles, and the clay mineral content of the slurry at a preset frequency.

[0112] The online detection unit includes an online concentration meter, an online particle size analyzer, and an online mineral analysis probe, which are respectively installed on the sampling branch of the feed pipeline of the settling tank, achieving continuous or intermittent parameter acquisition through bypass sampling. The online concentration meter can be a nuclear radiation densitometer or a Coriolis force densitometer; the online particle size analyzer can be a laser diffractometer or an ultrasonic attenuation particle size analyzer; and the online mineral analysis probe can be a near-infrared spectroscopy probe or an X-ray fluorescence analysis probe. The preset frequency is once every 5 minutes in this embodiment, but in other embodiments, it can be adjusted to once every 2 minutes, every 10 minutes, or every 15 minutes according to the fluctuation range of the incoming material. The measured values ​​of the acquired process parameters are used as input vectors in the form of digital signals and fed into a pre-built multi-factor correlation model in the controller via a fieldbus. The fieldbus can use industrial communication protocols such as PROFIBUS, Modbus, or EtherNet / IP.

[0113] The multi-factor correlation model is trained from the factor-index correspondence data obtained by the orthogonal experiment. It contains a mapping function between the solid mass percentage concentration, the proportion of fine particles and the clay mineral content, and the flocculant supply rate and the bottom flow discharge rate of the settling tank.

[0114] After calculation, the model outputs adjustment commands for the supply rate of the nonionic polymeric flocculant and for the discharge rate of the bottom flow from the settling tank.

[0115] The adjustment commands are transmitted via fieldbus to the frequency converter of the flocculant metering pump and the underflow discharge valve actuator, respectively, and executed.

[0116] The flocculant metering pump adjusts the injection flow rate of the nonionic polymeric flocculant by changing the pump stroke frequency or motor speed through a frequency converter driver according to the received supply rate adjustment command; the underflow discharge valve actuator adjusts the valve opening to change the discharge flow rate of the underflow slurry according to the received discharge rate adjustment command.

[0117] Through the aforementioned closed-loop process of acquisition, computation, and execution, the combination of physical attributes is dynamically maintained within the collaborative operation window during continuous production.

[0118] In this embodiment, the nonionic flocculant synergistic window red mud settling device includes a settling tank, a flocculant metering pump, an online detection unit, and a controller arranged sequentially along the process flow.

[0119] The settling tank has a cylindrical cone-bottom structure. The cylindrical part can be made of carbon steel or duplex stainless steel by welding, and the inner wall is lined with anti-corrosion lining. The upper part is equipped with a feed inlet and an overflow weir, and the bottom is equipped with an underflow discharge end, which is equipped with an electric or pneumatic valve actuator.

[0120] The flocculant metering pump is a plunger or diaphragm metering pump. Its hydraulic end can be made of stainless steel or engineering plastic to adapt to alkaline slurry conditions. Its drive end is equipped with a frequency converter, which can receive analog or digital adjustment signals from the controller.

[0121] The online detection unit includes an online concentration meter, an online particle size analyzer, and an online mineral analysis probe. Each detection instrument is connected to the controller's input module via a signal cable or fieldbus.

[0122] The controller internally incorporates the multi-factor correlation model and is equipped with a central processing unit, memory, and communication interface module; the controller can be a programmable logic controller or an industrial control computer.

[0123] After receiving the measured values ​​of the process parameters, the controller runs the multi-factor correlation model to generate adjustment instructions, and sends the adjustment instructions via fieldbus to the frequency converter of the flocculant metering pump and the valve actuator at the bottom flow discharge end of the settling tank, respectively or simultaneously, so as to dynamically regulate the supply rate of non-ionic polymeric flocculant and the bottom flow discharge rate of the settling tank.

[0124] This embodiment also provides a processing path for using a suspension slurry containing red mud particles obtained from the Bayer process of leaching kaolinite-type bauxite as the object to be separated.

[0125] By solidifying the compatibility between mineral source characteristics and the collaborative operation window into process flow selection conditions, the number of trial and error adjustments to process parameters can be reduced when switching mineral sources.

[0126] In this embodiment, the kaolinite content in the kaolinite-type bauxite is 5% to 15%, and the clay mineral content in the red mud slurry obtained after leaching by the dual-flow method is about 1.5%, which falls exactly in the central region of the collaborative operation window where the clay mineral content is 0.5% to 2.0%.

[0127] In other embodiments, if the kaolinite content in the kaolinite-type bauxite is high, causing the clay mineral content in the red mud slurry after leaching to exceed 2.0%, a hydrocyclone can be added to the grinding circuit for pre-desliming treatment to separate some clay minerals in advance, so that the clay mineral content in the slurry entering the settling tank falls back to within the collaborative operation window.

[0128] The working principle of this invention is roughly as follows:

[0129] First, a red mud particle suspension slurry with a predetermined combination of physical properties is obtained through step S100. This combination of physical properties includes three core parameters: solid mass percentage concentration, fine particle ratio, and clay mineral content.

[0130] Then, non-ionic polymeric flocculant is quantitatively supplied to the slurry through step S200. The flocculant molecular chain segments are used to form flocs with a three-dimensional network structure on the surface of red mud particles through adsorption bridging. The flocculation and sedimentation operation is carried out, and a solid-liquid separation system of upper clear liquid and lower sediment layer is formed in the sedimentation tank.

[0131] During the flocculation and sedimentation operation, the combination of physical properties is controlled in a closed loop through step S300: the online detection unit continuously collects the measured values ​​of the physical property parameters of the slurry and feeds them into the multi-factor correlation model. After the model calculates, it outputs adjustment commands for the flocculant supply rate and the underflow discharge rate. The actuator adjusts in real time according to the commands, so that the combination of physical properties is always maintained within a coordinated operation window. Within this window, the bridging efficiency of the non-ionic polymeric flocculant, the floc drainage rate, and the sedimentation layer compression rate form a coordinated matching relationship, thereby enabling the red mud sedimentation and separation process to maintain high solid-liquid separation efficiency within a wide range of incoming material fluctuations.

[0132] In summary, this application employs nonionic polyacrylamide as a flocculant, combined with a synergistic operation window configuration of 8% to 12% solid mass concentration, 15% to 25% fine particles with a particle size less than 75 micrometers, and 0.5% to 2.0% clay mineral content. Through a closed-loop control circuit consisting of an online detection unit, a multi-factor correlation model, and an actuator, the flocculant supply rate and the underflow discharge rate of the settling tank can be dynamically matched to the optimal range under industrial production conditions where the physical properties of the slurry fluctuate continuously. This helps to reduce the amount of alkali adhering to the underflow, increase the processing throughput per unit area of ​​the settling tank, and reduce the number of trial and error adjustments to process parameters when switching mineral sources or changing leaching conditions. It has certain engineering application value in the red mud solid-liquid separation process of alumina hydrometallurgy.

[0133] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method of non-ionic flocculant synergistic windowed red mud settling, characterised in that, Includes the following steps: Step S100: Provide a suspension slurry containing red mud particles to be separated, the slurry having a predetermined combination of physical properties; Step S200: A non-ionic polymeric flocculant is quantitatively supplied to the slurry provided in step S100, and flocculation and sedimentation are performed to form a solid-liquid separation system comprising an upper clear liquid and a lower sediment layer. Step S300: During the flocculation and sedimentation operation, the combination of physical properties is maintained within a collaborative operation window through closed-loop control, wherein the combination of physical properties includes the mass percentage concentration of solids in the slurry, the proportion of fine particles, and the clay mineral content.

2. The method for red mud sedimentation with a synergistic window of nonionic flocculant according to claim 1, characterized in that, The nonionic polymeric flocculant mentioned in step S200 is nonionic polyacrylamide.

3. The method for red mud sedimentation with a synergistic window of nonionic flocculant according to claim 2, characterized in that, The nonionic polyacrylamide has a molecular weight range of 14 million to 16 million.

4. The method for red mud sedimentation with a synergistic window of nonionic flocculant according to claim 1, characterized in that, The collaborative operation window mentioned in step S300 is specifically: The mass percentage concentration of the solid phase is 8% to 12%; The fine particles, on a dry basis, comprise 15% to 25% of the particles with a diameter less than 75 micrometers. The clay mineral content, on a dry basis, is 0.5% to 2.0%.

5. The method for red mud sedimentation with a synergistic window of nonionic flocculant according to claim 4, characterized in that, The solid phase has a mass percentage concentration of 10%, the particles with a diameter of less than 75 micrometers account for 20%, and the clay mineral content is 1.5%.

6. The method for red mud sedimentation with a synergistic window of nonionic flocculant according to claim 1, characterized in that, The clay mineral is kaolinite.

7. The method for red mud sedimentation with a synergistic window of nonionic flocculant according to claim 1, characterized in that, The suspension slurry containing red mud particles to be separated in step S100 is a diluted slurry obtained by treating bauxite through a two-flow leaching process.

8. The method for red mud sedimentation with a synergistic window of nonionic flocculant according to claim 1, characterized in that, It also includes an intelligent control step that is integrated in parallel with step S300: The online detection units deployed along the process flow collect measured values ​​of process parameters such as the mass percentage concentration of solid phase, the proportion of fine particles, and the clay mineral content of the slurry at a preset frequency. The measured values ​​of the process parameters are used as input vectors and fed into a pre-built multi-factor correlation model. The model calculates and outputs adjustment commands for the supply rate of the non-ionic polymeric flocculant and for the discharge rate of the bottom flow of the settling tank. The adjustment commands are transmitted to the frequency converter of the flocculant metering pump and the underflow discharge valve actuator via the fieldbus and executed, so that the combination of physical properties is dynamically maintained within the cooperative operation window.

9. A Bayer process red mud sedimentation and separation method for processing kaolinite-type bauxite, characterized in that, The suspension slurry containing red mud particles obtained by leaching kaolinite-type bauxite through the Bayer process is used as the object to be separated, and the non-ionic flocculant synergistic window red mud sedimentation method described in any one of claims 1 to 8 is executed.

10. A nonionic flocculant synergistic window red mud settling device, used to implement the nonionic flocculant synergistic window red mud settling method of claim 8, the device comprising a settling tank, a flocculant metering pump, an online detection unit, and a controller arranged sequentially along the process flow, characterized in that: The online detection unit is configured as follows: The measured values ​​of process parameters, such as the mass percentage concentration of solid phase, the proportion of fine particles, and the clay mineral content of the slurry, are collected and sent to the controller at a preset frequency. The controller internally embeds the multi-factor association model, and the controller is configured to: The system receives the measured values ​​of the process parameters, runs the multi-factor correlation model to generate adjustment commands, and sends the adjustment commands via fieldbus to the frequency converter of the flocculant metering pump and the valve actuator at the bottom flow discharge end of the settling tank, respectively or simultaneously, to dynamically regulate the supply rate of the non-ionic polymeric flocculant and the bottom flow discharge rate of the settling tank.

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