Characterization and segmented examination method for wall surface roughness in spiral chute sorting numerical test

Abstract

The invention relates to a characterization method of a wall surface roughness value in a spiral chute sorting numerical test, which comprises the following steps: under a selected operation condition, carrying out an actual mineral particle sorting test on a spiral chute, intercepting and separating products from different sections of a chute surface, and respectively measuring the actual ore pulp flow and iron grade of each product; generating a spiral chute computational domain based on the structure parameters of the spiral chute and the average wall surface roughness Ra of the chute surface; mineral particle sorting test results under actual and simulated conditions of the spiral chute are compared, product ore pulp flows and iron grades in different intervals of the chute surface under different roughness height Ks value conditions of a sorting numerical test are counted, and numerical comparison is carried out on the ore pulp flows and the iron grades in the same radial area; the method comprises the following steps: taking ore pulp flow and iron grade data in a sorting numerical value test, taking a Ks value with the minimum deviation from an actual sorting test numerical value as an actual wall surface roughness Ra under the same condition, and correspondingly obtaining an equivalent relational expression;

Description

Technical Field

[0001] The invention belongs to the field of fully automated products and relates to a method for characterizing and segmentally examining wall roughness in a spiral chute sorting numerical test. Background Art

[0002] Gravity separation has become the primary method used for ore separation and enrichment due to its low production cost, large production capacity and eco-friendly advantages. As a typical composite force field separation equipment, spiral chute is widely used in production processes such as ore resources and waste resource utilization due to its simple structure, small footprint and low cost. As the wear of the production chute surface increases, the on-site separation index decreases. Therefore, it is necessary to strengthen the theoretical and influencing mechanism research on roughness in order to provide a scientific basis for the design of chute surface materials and surface structures.

[0003] Patent [CN214811658U] discloses a wall surface with fish-scale protrusions, which has a good sorting effect. Patent [CN217910880U] discloses a wall structure composed of a friction pad, a wear-resistant layer, a rubber plate, and a plexiglass bottom plate, which can improve the sorting effect of mineral particles and extend the service life of the spiral chute surface. Patent [CN115742387A] discloses a method for repairing the damaged surface of a gravity-selection spiral chute. The repaired sorting effect and wear resistance are the same as those of a new chute. Patent [CN216936446U] discloses a spiral chute for gravity separation, which provides a replaceable chute surface, in which friction convex plates, friction convex blocks, and friction convex surfaces are provided, which can increase the friction force on the surface of the chute plate, which is beneficial for sorting mineral particles with relatively low density.

[0004] The screening of these designs and optimization combinations is generally based on a large number of physical tests, which consumes a lot of material and time costs, and lacks a method to fundamentally establish the influence mechanism of wall roughness. With the development of numerical simulation methods, high-precision numerical simulation experiments have created conditions for fundamentally revealing the influence mechanism of wall roughness on the flow field and particle motion behavior of the spiral chute. However, current numerical experiments rarely consider the influence of wall roughness, resulting in deviations between numerical simulations and actual separation processes. How to reasonably set the wall roughness of the spiral chute during the numerical simulation process is a necessary basis for identifying the influence mechanism of wall roughness, and is also the key to further forming a method for optimizing the design of trough surface roughness. Summary of the invention

[0005] In order to solve the above problems, the technical solution adopted by the present invention is: a method for characterizing the wall roughness value in a spiral chute sorting numerical test: comprising the following steps:

[0006] Uniformly distribute points across the entire spiral chute surface, measure the wall roughness at each point respectively, and average the measured values to obtain the average wall roughness Ra of the chute surface;

[0007] Under the selected operating conditions, conduct actual mineral particle separation tests on the spiral chute. Intercept separation products from different intervals of the chute surface, and measure the actual pulp flow rate and iron grade of each product respectively;

[0008] Generate a computational domain for the spiral chute based on the structural parameters of the spiral chute and the average wall roughness Ra of the chute surface;

[0009] Set the same simulation conditions for the spiral chute as those in the actual mineral particle separation test to conduct separation numerical tests, and perform numerical calculations on the pulp flow rate and iron grade of the products intercepted from different chute surface areas of the spiral chute;

[0010] Compare the results of mineral particle separation tests under actual and simulated conditions of the spiral chute, and statistically analyze the pulp flow rate and iron grade of the products in different intervals of the chute surface under different roughness height K s values. Conduct numerical comparison on the pulp flow rate and iron grade in the same radial region, and select the K s value with the smallest numerical deviation between the pulp flow rate and iron grade data in the separation numerical test and the actual separation test as the actual wall roughness Ra under the same conditions, and obtain the corresponding equivalent relationship accordingly.

[0011] Furthermore: The simulation conditions of the spiral chute include:

[0012] Import the hexahedral mesh of the computational domain in the discrete spiral chute into the CFD software Fluent, and set the multiphase flow model and turbulence model;

[0013] Set the inlet material parameters, computational region boundary conditions, and input the roughness value;

[0014] The multiphase flow model adopts the Multi-fluid VOF model, and the turbulence model adopts the RNG k-ε model;

[0015] The boundary conditions include the velocity inlet and pressure outlet of the spiral chute, the non-slip lower wall surface of the chute body, and the free-slip upper wall surface of the chute body. The pressure outlet is set to the local atmospheric pressure, that is, the relative pressure is 0;

[0016] The roughness value is controlled by the input roughness constant C s and roughness height K s values. The roughness constant C s is the default value of 0.5, and the roughness height is determined by the formula K s = 5 - 10Ra.

[0017] Furthermore, the wall roughness of each point is measured in the same direction as the mainstream direction in the spiral chute.

[0018] Furthermore, the expression of the equivalent relationship is as follows:

[0019] K s = c Ra

[0020] Where: c is a constant.

[0021] Furthermore, the structural parameters of the spiral chute include cross-sectional shape, outer radius, inner radius, pitch, and number of turns.

[0022] According to the segmented examination method of the characterization method of the wall roughness value in the spiral chute sorting numerical experiment described in any one of them, it includes the following steps:

[0023] Divide several spiral bands along the radial direction of the bottom wall of the chute to obtain segmented areas with freely adjustable wall conditions;

[0024] For the segmented examination experiment of the bottom wall roughness of the chute, set the roughness height K of the segmented area in the Fluent software s After setting, conduct a sorting numerical experiment to obtain the separation performance of the spiral chute when the wall roughness of each section area is adjusted.

[0025] Furthermore, when the spiral band is evenly divided into an inner-section spiral band, a middle-section spiral band, and an outer-section spiral band, for the separation performance, use wear-resistant materials for the wall of the middle-section spiral band.

[0026] A method for characterizing and segmentally examining the wall roughness in a spiral chute sorting numerical experiment provided by the present invention, by measuring the wall roughness of the actual spiral chute, based on actual sorting experiments and numerical experiments, verifying the equivalent relationship between the actual wall roughness Ra and the numerical roughness height K s To establish an equivalent relationship for mutual characterization, so as to realize the investigation of the separation results of mineral particles under different wall roughness conditions, and further by segmenting the radial direction of the chute surface, to realize the investigation of the influence of the wall roughness of different sections on the particle separation process and results. It has the following advantages:

[0027] 1. The equivalent relationship between the actual wall roughness Ra and the roughness height K established by the method for characterizing the wall roughness value of the spiral chute of the present invention can provide a basis for the reasonable setting of the wall roughness in the numerical experiment of the spiral chute separation process, and lay a foundation for accurately examining the influence of the wall roughness on the separation results of mineral particles; s

[0028] ​2. The method for segmentally examining the wall roughness of a spiral chute based on numerical experiments formed by the present invention has the outstanding feature of saving human and material resources, provides a feasible way to deeply reveal the influence mechanism of wall roughness in different sections on the particle separation process, and has important reference value for the selection of the wall material and its roughness of the spiral chute.

[0029] The present application provides a method for characterizing and segmentally examining the wall roughness value in the numerical experiment of spiral chute separation, which can not only save economic costs but also accurately examine the influence of wall roughness on the separation of mineral particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0031] Figure 1 is a flowchart of a method for characterizing the wall roughness value in the numerical experiment of spiral chute separation of the present invention;

[0032] Figure 2 is a diagram of the shape of the bottom of the spiral chute;

[0033] Figure 3 is a schematic diagram of the sectional measurement of the wall roughness of the spiral chute;

[0034] Figure 4 is a distribution diagram of the measurement results of the wall roughness of the spiral chute;

[0035] Figure 5 is a comparison diagram of the simulated value and the measured value of the pulp flow rate of the separated product;

[0036] Figure 6 is a comparison diagram of the simulated value and the measured value of the iron grade of the separated product;

[0037] Figure 7 is a schematic diagram of the sectional division of the radial area of the spiral chute surface;

[0038] Figure 8 is a separation efficiency curve when the wall roughness of the inner edge area of the spiral chute is adjusted;

[0039] Figure 9 is a separation efficiency curve when the wall roughness of the middle area of the spiral chute is adjusted;

[0040] Figure 10 is a separation efficiency curve when the wall roughness of the outer edge area of the spiral chute is adjusted. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0042] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part rather than all of the embodiments of the present invention. The following description of at least one exemplary embodiment is actually only illustrative and in no way constitutes a limitation on the present invention and its application or use. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0043] Figure 1 is a flowchart of a method for characterizing the wall roughness value in a numerical experiment of spiral chute separation of the present invention;

[0044] A method for characterizing the wall roughness value in a numerical experiment of spiral chute separation includes the following steps:

[0045] S11: Uniformly distribute points on the entire spiral groove surface of the spiral chute, measure the wall roughness of each point respectively, and average the measurement values to obtain the average wall roughness Ra of the groove surface;

[0046] The uniform distribution of points means that the measurement points are uniformly arranged along the main flow direction of the spiral chute;

[0047] The average wall roughness Ra is the arithmetic mean of the roughness measurement values of all measurement points;

[0048] S12: Under the selected operating conditions, conduct an actual mineral particle separation experiment on the spiral chute, intercept the separated products from different intervals of the chute surface, and measure the actual pulp flow rate and iron grade of each product respectively;

[0049] Obtained by measurement, time sampling is carried out in the actual separation experiment and separation index data is obtained. To ensure the accuracy of the separation experiment, 3 repeated experiments were carried out in total, and the final result was the average value.

[0050] The operating conditions include the feed mineral composition, feed flow rate and feed solid mass concentration;

[0051] The pulp flow rate of each product is the pulp volume of the product per unit time;

[0052] The iron grade of each product is the criterion index for evaluating the result of the separation experiment;

[0053] S13: Generate the computational domain of the spiral chute based on the structural parameters of the spiral chute and the average wall roughness Ra of the chute surface;

[0054] S14: Set the simulation conditions of the spiral chute identical to those of the actual mineral particle separation test to conduct a separation numerical test, and perform numerical calculations on the pulp flow rate and iron grade of the products intercepted from different chute surface areas of the spiral chute;

[0055] S15: Compare the results of the mineral particle separation tests under the actual and simulated conditions of the spiral chute, count the pulp flow rate and iron grade of the products in different intervals of the chute surface under different roughness height K s values, conduct a numerical comparison of the pulp flow rate and iron grade of the products in the same radial region, and take the K s value with the smallest numerical deviation between the pulp flow rate and iron grade data of the separation numerical test and the actual separation test numerical values as the actual wall roughness Ra under the same conditions, and obtain the equivalent relationship accordingly.

[0056] The steps S11 / S12 are executed in parallel and then the steps S13 / S14 / S15 are executed sequentially;

[0057] The structural parameters of the spiral chute include the cross-sectional shape, outer radius, inner radius, pitch, and number of turns;

[0058] To generate the computational domain of the spiral chute, use the 3D modeling software SolidWorks to establish the geometric model of the computational domain inside the target spiral chute, and then import it into the ICEM CFD software to discretize the computational domain into hexahedral meshes;

[0059] Furthermore: The simulation conditions of the spiral chute include:

[0060] Import the hexahedral meshes of the computational domain inside the discretized spiral chute into the CFD software Fluent, and set the multiphase flow model and turbulence model; The results under different multiphase flow models and turbulence models would originally be inconsistent, but this method can also be used for verification under different turbulence models and multiphase flow models, but the results may be different;

[0061] Set the inlet material parameters, computational region boundary conditions, and input the roughness value;

[0062] The inlet material conditions include the inlet velocities of the fluid and particles, and the volume fractions (mass ratios) of different particles

[0063] The multiphase flow model adopts the Multi-fluid VOF model, and the turbulence model adopts the RNG k-ε model;

[0064] The boundary conditions include the velocity inlet and pressure outlet of the spiral chute, the non-slip lower wall surface of the chute body, and the free-slip upper wall surface of the chute body, where the pressure outlet is set to the local atmospheric pressure, i.e., the relative pressure is 0;

[0065] The roughness value is controlled by the input roughness constant C s and roughness height K s values. Among them, the roughness constant C s is the default value of 0.5, and the roughness height is determined by the formula K s = 5 - 10Ra.

[0066] Furthermore: The expression of the equivalent relationship formula is as follows:

[0067] K s = c Ra

[0068] where: c is a constant;

[0069] In the sorting numerical test and the actual sorting test results, the pulp flow rate and iron grade in the same radial region are numerically compared, and the K s value of the one with a higher numerical test data coincidence degree is taken as the actual wall surface roughness Ra under the same conditions, and the equivalent relationship formula K s = c Ra is obtained accordingly;

[0070] According to the step-by-step examination method of the characterization method of the wall surface roughness value in any one of the above-mentioned spiral chute sorting numerical tests, it includes the following steps:

[0071] S21: Divide several spiral bands along the radial direction on the bottom wall surface of the chute, and accordingly obtain segmented regions with freely adjustable wall conditions;

[0072] When dividing several spiral bands along the radial direction on the bottom wall surface of the chute, the calculation domain grid of the spiral chute needs to be cut in the same region during the wall surface region division to generate different bottom wall surfaces of the chute, thereby obtaining segmented regions with freely adjustable wall conditions;

[0073] S22: Conduct a segmented examination test on the roughness of the bottom wall surface. In the Fluent software, after setting the corresponding roughness height K s for the segmented region, conduct a numerical test to obtain the separation performance of the spiral chute when the wall surface roughness of each segment region is adjusted. Further, through the segmented optimization analysis of the wall surface roughness, obtain the control measures: When the spiral band is evenly divided into the inner segment spiral band, the middle segment spiral band, and the outer segment spiral band, for the separation performance, use wear-resistant materials for the wall surface of the middle segment spiral band.

[0074] The corresponding roughness height K s setting, where the corresponding roughness height K sSet according to the measured value of the actual wall roughness Ra and its combination; if there is no actual wall roughness value for reference, an assumed combination is used, such as setting the wall roughness to all uniform values, or arranging the wall roughness in different regions to increase or decrease sequentially according to the region, etc.

[0075] The separation performance of the spiral chute when adjusting the wall roughness of each section of the area is obtained. The separation performance is evaluated by the separation efficiency, and the separation efficiency is the difference between the recovery rates of the target minerals and gangue minerals in the concentrate product.

[0076] The control measures obtained from the segmented optimization analysis of the wall roughness are based on the calculation results of the separation performance.

[0077] The steps S21 and S22 are executed in sequence.

[0078] Example 1: A method for characterizing the wall roughness value in a numerical experiment of spiral chute separation, the flow chart of which is as Figure 1 shown, including the following steps:

[0079] S1. Uniformly distribute points on the entire spiral chute surface, measure the wall roughness of each point respectively, and average the measured values to obtain the average wall roughness Ra of the chute surface.

[0080] The structural parameters of the target spiral chute include the cross-sectional shape, outer radius, inner radius, pitch, and number of turns. The shape of the chute bottom is obtained through actual measurement based on a laboratory-type spiral chute with a diameter of 400 mm. The results are as Figure 2 shown, and the numerical values of the structural parameters are shown in Table 1.

[0081] Table 1 List of structural parameters of the spiral chute

[0082] Structure parameter Numerical value Outer radius (R) 200 mm <![CDATA[Inner radius (r 0 )]]> 50 mm Pitch (P) 240 mm Number of turns of current flow 3.25

[0083] The uniform distribution of points means that the measurement points are uniformly arranged along the mainstream flow direction of the spiral chute. One turn of the chute surface is evenly divided into 8 equal parts along the spiral direction, and the same position range of each part of the area is measured. The measurement schematic diagram is as Figure 3 shown;

[0084] The average wall roughness Ra is the arithmetic mean of the roughness measured values of all measurement points. The arithmetic mean roughness Ra is selected as the measurement index of the wall roughness. The measurement equipment uses the PS1-M300 type handheld roughness meter produced by German Mahr Precision Measuring Instrument Company. The measurement results of the wall roughness Ra of the chute surface with 24 equal parts in three turns are as Figure 4 shown. For the convenience of subsequent verification of the wall roughness in numerical simulation, the arithmetic mean value Ra = 4.61 μm of the measurement data is taken as the overall wall roughness of the chute surface.

[0085] S2. Based on the spiral chute, conduct actual separation tests on mineral particles under the selected operating conditions. Intercept the separated products from different intervals on the chute surface, and measure the pulp flow rate and iron grade of each product respectively;

[0086] The operating conditions include the feed mineral composition, feed flow rate, and feed solid mass concentration. Among them, the feed mineral composition: the target mineral is hematite with a density of 4950 kg / m 3 , select the median particle size to be 107.97 μm, the gangue mineral is quartz with a density of 2650 kg / m 3 , select the median particle size to be 105.49 μm, and the iron grade in the feed is 46.12%; the feed flow rate is 12 L / min (7.2 m 3 / h), and the solid mass concentration in the feed is 16.74%;

[0087] The pulp flow rate of each product is the pulp volume of the product in different intervals per unit time;

[0088] The iron grade of each product is the criterion index for evaluating the separation test results;

[0089] S3. Generate the calculation domain of the spiral chute. Use the 3D modeling software SolidWorks to establish the geometric model of the calculation domain inside the target spiral chute, and then import it into the ICEM CFD software to discretize the calculation domain into hexahedral meshes;

[0090] S4. Set the simulation conditions of the spiral chute. Import the mesh generated in step S3 into the CFD software Fluent, set the multiphase flow model and turbulence model, further set the inlet material parameters, calculation area boundary conditions, input the roughness value, and then perform numerical calculations;

[0091] The multiphase flow model and turbulence model adopt the Multi-fluid VOF model and the RNG k-ε model respectively;

[0092] The boundary conditions include the velocity inlet and pressure outlet of the spiral chute, the non-slip lower wall surface and the free-slip upper wall surface. Among them, the pressure outlet is set to the local atmospheric pressure, that is, the relative pressure is 0;

[0093] The roughness value is controlled by the input roughness constant C s and roughness height K s values. Among them, the roughness constant C s is the default value of 0.5, and the roughness height K s is selected and set based on comprehensively including the literature information of similar flow processes. A total of 5 K s values of 0.01, 0.02, 0.03, 0.04, and 0.05 mm are set within the range of 5 - 10 Ra;

[0094] S5. Compare the test results of the spiral chute under actual and simulated conditions, and count the product pulp flow rate and iron grade in different intervals of the chute surface under the conditions of 0.01, 0.02, 0.03, 0.04, and 0.05 mm for 5 K s values. Comprehensively analyze the results of the numerical test and the actual separation test, and obtain the equivalent relationship K s = c Ra accordingly; comprehensively compare the pulp flow rate and iron grade of the products in different regions in the actual test and the numerical test, and select the 2-3 groups with the closest numerical results as the judgment, and take their intersection to obtain the condition with the highest degree of coincidence;

[0095] Compare the mineral particle separation test results of the spiral chute under actual and simulated conditions, and count the product pulp flow rate and iron grade in different intervals of the chute surface under different roughness height K s values. Conduct a numerical comparison of the pulp flow rate and iron grade in the same radial region, and take the K s value of the pulp flow rate and iron grade data of the separation numerical test with the smallest numerical deviation from the actual separation test numerical value as the actual wall roughness Ra under the same conditions, and obtain the equivalent relationship accordingly.

[0096] In the comprehensive analysis of the results of the numerical test and the actual separation test, divide the outlet of the spiral chute into an inner area, a middle area, and an outer area in the results of the numerical test and the actual separation test. In the numerical test, the product pulp flow rate and iron grade in each interval can be directly obtained through the post-processing calculation of the CFD-POST software. In the actual test, time sampling is carried out and the separation index data is obtained. Conduct a numerical comparison of the pulp flow rate and iron grade of the products in each interval, and take the K s value of the numerical test data with a higher degree of coincidence as the actual wall roughness Ra under the same conditions, and obtain the equivalent relationship K s = c Ra accordingly; the comparison of the test results is as Figure 5 and Figure 6 shown. When different K s settings are used, there are different degrees of deviation between the simulated value and the measured value of the index. Among them, the deviation is the smallest when Ks is set to 0.03 mm. Therefore, the equivalent relationship K s ≈ 6.51Ra can be calculated.

[0097] 1. In the actual separation test, time sampling is carried out and the separation index data is obtained. To ensure the accuracy of the separation test, a total of 3 repeated tests are carried out, and the final result is the average value.

[0098] 2. Obtain the pulp flow rate and iron grade of the corresponding products through simulation calculation.

[0099] 3. Compare the results of the actual separation test and the numerical test, and use different K sThere are deviations of varying degrees between the simulated values and the measured values of the indicators obtained when setting values, and the deviation is the smallest under the setting value of 0.03mm.

[0100] A segmented investigation method for the characterization method of wall roughness values in a numerical experiment of spiral chute separation, comprising the following steps:

[0101] S6. In the ICEM CFD software, several spiral bands are divided along the radial direction of the bottom wall of the chute, and accordingly, segmented regions where the wall conditions can be freely adjusted are obtained;

[0102] When dividing several spiral bands along the radial direction of the bottom wall of the chute and performing wall region division in the ICEM CFD software, it is necessary to first perform the same regional cutting on the mesh of the calculation domain of the spiral chute to generate different bottom walls of the chute, thereby obtaining segmented regions where the wall conditions can be freely adjusted. The schematic diagram of the single - loop segmentation of the chute surface of the spiral chute into the inner edge, middle, and outer edge regions in the radial direction is as Figure 7 shown;

[0103] S7. Segmented investigation test of the bottom wall roughness. In the Fluent software, after setting the corresponding roughness height K s for the segmented regions, a numerical experiment is carried out to obtain the separation performance of the spiral chute when the wall roughness of each segmented region is adjusted, and further obtain the control measures through segmented optimization analysis of the wall roughness.

[0104] The corresponding roughness height K s is set, where the corresponding roughness height K s is set according to the measured value of the actual wall roughness Ra and its combination; in this experiment, according to the combined setting, on the basis of the overall wall equivalent roughness height K s being 0.03mm, the wall roughness heights K s of the inner edge, middle, and outer edge regions are further set to 0.01, 0.05, 0.1, and 0.2mm respectively;

[0105] The structural parameters of the numerical experiment are the same as those in step S2. In the operating conditions, referring to the ore - feeding conditions of the spiral chute beneficiation section of a certain production site, both hematite and quartz are set at two particle - size levels of coarse and fine, and the ore is proportioned and pulp - adjusted according to the ratio to make the ore - feeding conditions such as iron grade and concentration consistent with the site. The results of the separation efficiency of the test particles of hematite and quartz after adjusting the local wall roughness are as Figures 8 - 10 shown;

[0106] The separation performance of the spiral chute obtained when adjusting the wall roughness of the segmented regions is evaluated by the separation efficiency, and the separation efficiency is the difference between the recovery rates of the target minerals and gangue minerals in the concentrate product;

[0107] The control measures obtained from the segmented optimization analysis of the wall surface roughness are based on the separation performance calculation results. It can be seen from the analysis that as the roughness of the middle and outer edge regions increases, the maximum separation efficiency of hematite and quartz will decrease significantly, thereby reducing the separation performance of the spiral chute. Only when the roughness of the inner edge region is greater than 0.1 mm does it show an obvious decrease. Among them, the optimal product segmentation position only shifts significantly outward when the roughness of the middle region increases.

[0108] Furthermore, in order to obtain better and stable separation prediction indicators for the spiral chute, this method can propose specific control measures for the segmented optimization and control of the roughness of the chute wall surface: prevent the overall and local wall surface roughness values of the chute surface from being too large to ensure the stability of the separation performance of the spiral chute; strengthen the control of the roughness of the middle wall surface of the chute bottom, and at the same time improve the wear resistance of the wall surface in the middle region to expand the radial distribution difference between hematite and quartz; the inner edge of the chute bottom should be kept smooth to promote the inward migration movement of hematite, thereby improving the separation performance of the spiral chute.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for characterizing the wall roughness value in a spiral chute sorting numerical test, characterized in that: The steps include: Evenly distribute points on the entire spiral groove surface of the spiral chute, measure the wall roughness of each point respectively, and average the measured values ​​to obtain the average wall roughness Ra of the groove surface; Under the selected operating conditions, actual mineral particle separation tests were carried out on the spiral chute, and the separated products were intercepted from different sections of the chute surface, and the actual slurry flow rate and iron grade of each product were measured respectively; Generate the calculation domain of spiral chute based on the structural parameters of spiral chute and the average wall roughness Ra of the chute surface; The numerical separation test was conducted under the same spiral chute simulation conditions as the actual mineral particle separation test, and the pulp flow rate and iron grade of the intercepted products in different trough surface areas of the spiral chute were numerically calculated. Comparing the test results of mineral particle separation under actual and simulated conditions in spiral chute, statistical sorting numerical test results of different roughness heights K s The slurry flow rate and iron grade of the products in different intervals of the slot surface under the same radial condition are compared numerically. The slurry flow rate and iron grade data of the separation numerical test are taken, and the K with the smallest deviation from the actual separation test value is selected. s The value is taken as the actual wall roughness Ra under the same conditions, and the equivalent relationship is obtained accordingly.

2. The method for characterizing the wall roughness value in the spiral chute sorting numerical test according to claim 1 is characterized in that: The spiral chute simulation conditions include Import the computational domain hexahedral mesh of the discrete spiral chute into the CFD software Fluent, and set the multiphase flow model and turbulence model; Set the inlet material parameters, calculate the area boundary conditions, and input the roughness value; The multiphase flow model adopts the Multi-fluid VOF model, and the turbulence model adopts the RNG k-ε model; The boundary conditions include the velocity inlet and pressure outlet of the spiral chute, the non-slip lower wall of the chute and the free-slip upper wall of the chute, wherein the pressure outlet is set to the local atmospheric pressure, that is, the relative pressure is 0; The roughness value is determined by inputting the roughness constant C s and roughness height K s Value control, where the roughness constant C s The default value is 0.5, and the roughness height is determined by K s =Determined by the formula of 5~10Ra.

3. The method for characterizing the wall roughness value in the spiral chute sorting numerical test according to claim 1 is characterized in that: The wall roughness of each point is measured in a direction that is the same as the mainstream direction in the spiral chute.

4. The method for characterizing the wall roughness value in the spiral chute sorting numerical test according to claim 1 is characterized in that: The expression of the equivalent relation is as follows: K s =c Ra Where: c is a constant.

5. The method for characterizing the wall roughness value in the spiral chute sorting numerical test according to claim 1 is characterized in that: The structural parameters of the spiral chute include cross-sectional shape, outer radius, inner radius, pitch and number of turns.

6. A segmented examination method for characterizing the wall roughness value in a spiral chute sorting numerical test according to any one of claims 1 to 5, characterized in that: The following steps are involved: The groove bottom wall is divided into a number of spiral bands along the radial direction, and corresponding segmented areas for freely adjusting the wall conditions are obtained; The roughness of the groove bottom wall is tested in sections, and the corresponding roughness height K of the sectioned area is calculated in Fluent software. s After the setting, numerical separation tests were carried out to obtain the separation performance of the spiral chute when the wall roughness of each section was adjusted.

7. The segmented examination method for characterizing the wall roughness value in the spiral chute sorting numerical test according to claim 6 is characterized by: When the spiral belt is evenly divided into an inner spiral belt, a middle spiral belt and an outer spiral belt, wear-resistant material is used on the wall surface of the middle spiral belt in order to improve separation performance.

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