Slurry high gradient magnetic separator separation tank and flow equalizing plate used thereby

Abstract

This invention discloses a high-gradient magnetic separator separation tank for slurry and a flow equalization plate used therein. The separation tank includes a magnetically concentrated medium filling area and a slurry distribution structure symmetrically arranged on both sides of the magnetically concentrated medium filling area. The slurry distribution structure includes a buffer zone I, a flow equalization plate, a buffer zone II, and a uniform perforation plate arranged sequentially. The flow equalization plate uses radially elongated holes and adjacent annular perforation areas with staggered openings, and a transition treatment is made in the transition area between adjacent annular perforation areas. In the separation tank of this invention, the flow equalization plate with radially elongated holes and adjacent annular perforation areas with staggered openings can obtain optimization indicators closest to the simple model. Furthermore, the transition treatment of openings in the transition area between adjacent annular perforation areas can significantly reduce the effective range of fluid vortices, resulting in better overall flow equalization of the slurry distribution structure and allowing for a longer length of the magnetically concentrated medium filling area, thus greatly improving the overall separation efficiency of the separation tank.

Description

Technical Field

[0001] This invention belongs to the technical field of high gradient magnetic separators for slurries, and particularly relates to a separation tank for a high gradient magnetic separator for slurries and a flow equalization plate used therein, so as to make the flow velocity of the separation tank cross section uniform. Background Technology

[0002] High-gradient magnetic separators for slurries utilize magnetic media to generate magnetic adsorption forces on magnetic mineral particles in a magnetic field that are 1000 to 10000 times stronger than those in an open magnetic field, thus holding an important position in the separation of weakly magnetic minerals. The excitation coils typically use conventionally conductive materials—copper or aluminum; in recent years, superconducting materials have also become increasingly common. Besides the traditional vertically placed separation tank, horizontally placed separation tanks have also emerged. The former is often matched with rapidly rising and falling magnetic fields, while the latter is often matched with periodically entering and exiting the magnetic field. The inlet and outlet pipes have much smaller cross-sectional areas compared to the separation tank. The entry and exit of the slurry in the separation tank are accompanied by fluid dynamic expansion and contraction effects, respectively. The resulting local eddies and uneven flow velocities lead to uneven distribution of magnetic adsorption capacity, resulting in low utilization efficiency of the magnetic media and a short effective magnetic separation time in a single working cycle, thus affecting the equipment's performance.

[0003] Conversely, keeping other conditions constant, the efficiency of a high-gradient magnetic separator for slurry can be significantly improved simply by homogenizing the flow velocity across the separator cross-section. Various types of separator / separation zone slurry distribution structures have been developed for this purpose.

[0004] The simplified structural diagram of the magnetic separator disclosed in the invention "High Gradient Magnetic Separator for Slurry Without Disassembly and Washing" (Authorization Announcement No. CN205236166U, Authorization Announcement Date 2016.05.18) shows that the separation zone filled with magnetically focusing medium is located between the upper and lower magnetic heads. The opening layout of the upper and lower magnetic heads is a gradient opening, that is, the number of openings increases sequentially on concentric circles from the inside to the outside. The feed collection tank and the discharge collection tank are cylindrical and symmetrically arranged with respect to the horizontal center plane of the separation zone. Except for the central branch pipe, each branch pipe extends from the cylinder wall and connects to the corresponding hole of the magnetic head.

[0005] The simplified structural diagram of the magnetic separator published in "Optimization and Improvement of Electromagnetic Slurry High Gradient Magnetic Separator and its Application in Non-metallic Mineral Magnetic Separation" ("Ceramics" magazine, January 2016) shows that a buffer zone is added above the upper magnetic head. The upper flange of the buffer zone has gradient openings. The bottom and top of the collection tank are both arc-shaped, and the central opening at the top connects to an external pipeline. Each branch pipe extends from the arc surface at the bottom and connects to the corresponding openings on the upper flange of the buffer zone. A frustum-shaped (or funnel-shaped) flange is added below the lower magnetic head, and the central opening of the flange connects to an external pipeline.

[0006] The simplified structural diagrams of the magnetic separators published in "Industrial Application of HTDZ High Gradient Slurry Magnetic Separator in Iron Removal and Purification of Kaolin" ("Ceramics" magazine, January 2017) and "Application of Electromagnetic Slurry Magnetic Separator in Purification of Non-metallic Minerals" ("Ceramics" magazine, May 2020) show that a buffer zone height has been added above the upper magnetic head. The buffer zone is connected to the outside pipe through a frustum with a central opening. The conical flange structure below the lower magnetic head is the same as that in "Optimization and Improvement of Electromagnetic Slurry High Gradient Magnetic Separator and its Application in Magnetic Separation of Non-metallic Minerals".

[0007] The simplified structural diagram of the magnetic separator disclosed in the invention patent "Electromagnetic Slurry Magnetic Separator" (application publication number CN109127125A, application publication date 2019.01.04) shows that the outer structure of the upper and lower magnetic heads is symmetrically arranged with respect to the horizontal center plane of the separation zone. A short buffer zone is set outside the magnetic heads, and a flat flange with gradient openings is set outside the buffer zone. The bottom of the collection tank is flat, and each branch pipe passes through the bottom flange and connects to the outer flange of the buffer zone. The top is arc-shaped and the central opening is connected to the external pipeline.

[0008] The simplified structural diagram of the magnetic separator published in "Research and Application of SJ-1000 High Gradient Magnetic Separator for Slurry" (Modern Mining Magazine, April 2019, Issue 4) shows that a short buffer zone is set outside the upper and lower magnetic heads. A flat flange with gradient openings is set outside the buffer zone. The two collection tanks are cylindrical and symmetrically arranged with respect to the horizontal center plane of the separation zone. Except for the central branch pipe, each branch pipe extends out from the cylinder wall. The flange openings outside the collection tanks are connected to the external pipeline.

[0009] The accompanying drawings of the invention "Magnetic Pole Device and Electromagnetic Slurry Separator" (authorization announcement number CN211838455U, authorization announcement date 2020.11.03) show that the upper and lower magnetic heads have a central opening and are processed into a frustum shape facing the magnetic medium, with guide plates evenly distributed along the circumference inside the frustum.

[0010] The invention "An Electromagnetic Separator for Slurry" (authorization announcement number CN213494724U, authorization announcement date 2021.06.22) discloses a magnetic separator structure in which the height of the outer buffer zones of the upper and lower magnetic heads is significantly increased; the upper buffer zone is cylindrical, with an opening in the center of the outer flange connected to an external pipe; the lower buffer zone is frustoconical, with an opening at the top of the cone connected to an external pipe.

[0011] The invention "Multi-cavity series separation tank of reciprocating series tank superconducting magnetic separator with uniform slurry distribution structure" (authorization publication number CN215429597U, authorization announcement date 2022-01-07) symmetrically sets flow equalization plates and buffer zones on both sides of the separation zone, and the buffer zones are directly connected to external pipelines.

[0012] Fluid dynamics analysis and equipment operation results show that the first slurry distribution structure (collection tank + branch pipe + gradient-aperture flange / magnetic head) can achieve a certain degree of uniform slurry distribution, but its effect is poor and the large aperture spacing leads to more local fluid vortices, further deteriorating the uniformity of the flow velocity in the separation zone. The second slurry distribution structure (cone + guide plate) does not significantly improve the slurry distribution effect compared to the first structure. The third slurry distribution structure (buffer zone + gradient aperture) provides greater optimization space for uniform slurry distribution. Symmetrically setting the slurry distribution structures on both sides of the separation zone is more conducive to the uniformity of the flow velocity in the separation zone. In the third slurry distribution structure, the gradient aperture is the dominant factor, that is, for the optimized gradient aperture, only a shorter buffer zone is needed; while for the poor gradient aperture, even if the buffer zone length exceeds the allowable range of the equipment, a reasonable uniform slurry distribution effect cannot be achieved. Summary of the Invention

[0013] The purpose of this invention is to provide a high gradient magnetic separator tank for slurry with good flow equalization and high separation efficiency, and the flow equalization plate used therein.

[0014] This invention is achieved through the following technical solution:

[0015] The high-gradient magnetic separator tank for slurry includes a magnetic medium filling zone and slurry distribution structures symmetrically arranged on both sides of the magnetic medium filling zone. The slurry distribution structure includes a buffer zone I, a circular flow equalization plate, a buffer zone II, and a circular uniform perforation plate arranged sequentially. The buffer zone I consists of a frustum section on the outer side, which includes a slurry outlet or inlet, and a straight cylindrical section on the inner side. The buffer zone II only contains the straight cylindrical section. The flow equalization plate is provided with holes formed by alternating radial elongated holes and adjacent annular opening areas. In the transition area between adjacent annular opening areas, the openings in the adjacent areas extend to the transition area in an arc shape to provide a transition treatment.

[0016] Preferably, the flow equalization plate is radially divided into n opening regions and (n-1) transition regions, and the opening structure on the flow equalization plate is as follows:

[0017] 1. The holes in each region are evenly distributed along the circumference, and the holes in adjacent regions are staggered, which plays a dominant role in the uniformity of the cross-sectional flow velocity in the magnetic medium filling region.

[0018] 2. The two sides of each hole are part of the radius of the circular plate, so that the opening area maintains the same opening ratio in the radial direction;

[0019] 3. The edges of each hole should be rounded to reduce local fluid resistance.

[0020] Fourth, the openings in adjacent areas extend into the transition area in an arc shape to significantly reduce the range of fluid vortex effect. If the local porosity is too high, the plate thickness should be appropriately increased to ensure the overall plate strength.

[0021] A flow equalization plate is a plate through which the flow velocity is approximately equal at all points. A uniform orifice plate, on the other hand, has a uniform orifice density and distribution. When fluid flows through a uniform orifice plate, it does not have a flow equalization effect; it simply maintains the original flow velocity.

[0022] The reason for adopting the above-mentioned structural design for the flow equalization plate in this invention is that the inventors discovered through research that: First, the method of using radial elongated holes and adjacent annular opening regions to stagger the openings makes the measured flow equalization effect closest to the calculation results of the fluid model; Second, the transition region between adjacent annular opening regions is treated by extending the openings of adjacent regions in an arc shape to the transition region. Compared with the traditional opening method without such a transition treatment, the effective range of fluid vortices can be significantly reduced, because when the fluid encounters a place without a transition, it forms a strong vortex and generates strong turbulence. The transition method of this invention improves this to the greatest extent.

[0023] Therefore, the flow equalization plate designed according to the above method can make the flow equalization effect of the slurry distribution structure adopted in this invention closest to the fluid dynamics optimization result. Because of this, when using an effective flow equalization plate, the buffer length can be shortened, thus obtaining the shortest buffer I length and buffer II length.

[0024] This invention is applicable not only to horizontal feeding and discharging methods but also to vertical feeding and discharging methods, and it is applicable not only to conventional magnetic separators but also to superconducting magnetic separators.

[0025] Preferably, the support is located at the unperforated part of the outer edge of the flow equalization plate. The selected porosity of the outermost perforated area is matched with the plate thickness. That is, if the local porosity is too large, the plate thickness is appropriately increased to control the deformation of the entire plate under the action of fluid, or in other words, to have sufficiently small deformation under the action of magnetic field force and fluid force.

[0026] Preferably, the flow equalization plate is alternately divided into three opening regions and two transition regions along the radial direction.

[0027] Preferably, the flow equalization plate is made of non-magnetic stainless steel.

[0028] The beneficial effects of this invention are:

[0029] The high-gradient magnetic separator tank and its flow equalization plate of this invention have an ingenious structure. The flow equalization plate uses radial elongated holes and adjacent annular opening areas in an alternating manner to make the measured flow equalization effect closest to the calculation results of the fluid model. The transition treatment of the opening area between adjacent annular opening areas can significantly reduce the range of fluid vortex effect, so that the overall flow equalization effect of the slurry distribution structure is closest to the fluid dynamics optimization result, so as to maximize the separation efficiency of the magnetic media filling zone. That is, it maximizes the offsetting of the local vortex and uneven flow velocity caused by the expansion and contraction effects of fluid dynamics when the slurry enters and exits the separator tank, which leads to uneven distribution of magnetic adsorption capacity. This increases the utilization efficiency of the magnetic media and extends the effective magnetic separation time in one working cycle, thereby improving the efficiency of the equipment. It can also shorten the length of buffer zone I and buffer zone II, and thus obtain the longest magnetic media filling zone, which further improves the separation efficiency. Moreover, this structure has a wide range of applications. It is suitable for both horizontal and vertical feeding and discharging methods, and it is suitable for both conventional magnetic separators and superconducting magnetic separators, making it extremely practical. Attached Figure Description

[0030] For ease of explanation, the present invention will be described in detail below with reference to specific embodiments and accompanying drawings.

[0031] Figure 1 This is a schematic diagram of the separation tank structure according to an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the opening layout of the flow equalization plate in an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the separation tank of the present invention applied to a high gradient magnetic separator for slurry with a horizontal feed / discharge method;

[0034] Figure 4 This is a schematic diagram of the separation tank of the present invention applied to a high gradient magnetic separator for slurry with vertical feed / discharge method;

[0035] Figure 5 This is a flow velocity distribution diagram inside the separator without a flow equalizer.

[0036] Figure 6 This is a flow velocity distribution diagram inside the separation tank in an embodiment of the present invention;

[0037] Figure 7 This is a flow velocity distribution diagram with streamlines inside the separator without a flow equalizer.

[0038] Figure 8 This is a flow velocity distribution diagram with streamlines inside the separation tank in an embodiment of the present invention;

[0039] Figure 9This is a velocity distribution diagram of a different streamline in a separator without a flow equalizer.

[0040] Figure 10 This is a flow velocity distribution diagram with another streamline inside the separation tank in an embodiment of the present invention;

[0041] in Figures 5-10 In the middle, the unit of the numerical value on the right is m / s. Detailed Implementation

[0042] like Figure 1-4 As shown, the high-gradient magnetic separator tank for slurry includes a magnetic media filling zone 1 and slurry distribution structures symmetrically arranged on both sides of the magnetic media filling zone 1. The slurry distribution structure includes a buffer zone I2, a circular flow equalization plate 3, a buffer zone II4, and a circular uniform perforation plate 5 arranged sequentially. The buffer zone I2 consists of a frustum-shaped section on the outer side, including a slurry outlet or inlet, and a straight cylindrical section on the inner side. The buffer zone II4 contains only the straight cylindrical section. That is, the slurry distribution structure <buffer zone I + flow equalization plate + buffer zone II + uniform perforation plate> is symmetrically arranged on both sides of the magnetic media filling zone. The flow equalization plate has holes 6 formed by alternating radial elongated holes and adjacent annular opening areas. In the transition area between adjacent annular opening areas, the openings in the adjacent areas extend in an arc shape to the transition area to provide a transition treatment.

[0043] The flow equalization plate is alternately divided into n opening regions and (n-1) transition regions along the radial direction. The openings on the flow equalization plate have the following characteristics:

[0044] 1. The holes in each region are evenly distributed along the circumference, and the holes in adjacent regions are staggered, which plays a dominant role in the uniformity of the cross-sectional flow velocity in the magnetic medium filling region.

[0045] 2. The two sides of each hole are part of the radius of the circular plate, so that the opening area maintains the same opening ratio in the radial direction;

[0046] 3. The edges of each hole should be rounded to reduce local fluid resistance.

[0047] Fourth, the openings in adjacent areas extend into the transition area in an arc shape to significantly reduce the range of fluid vortex effect. If the local porosity is too high, the plate thickness should be appropriately increased to ensure the overall plate strength.

[0048] A flow equalization plate is a plate through which the flow velocity is approximately equal at all points. A uniform orifice plate, on the other hand, has a uniform orifice density and distribution. When fluid flows through a uniform orifice plate, it does not have a flow equalization effect; it simply maintains the original flow velocity.

[0049] In this embodiment, the support is located at the unperforated part of the outer edge of the flow equalization plate. The selected perforation ratio of the outermost perforated area is matched with the plate thickness. That is, if the local porosity is too large, the plate thickness is appropriately increased to control the deformation of the entire plate under the action of fluid, or in other words, to have sufficiently small deformation under the action of magnetic field force and fluid force.

[0050] In this embodiment, the flow equalization plate is made of non-magnetic stainless steel.

[0051] In this embodiment, the gradient opening ratio of the flow equalization plate, the length of buffer zone I, and the length of buffer zone II in the slurry distribution structure can also be calculated and optimized using a simple fluid dynamics calculation model at a specified flow rate, and the optimal value is selected through comparison.

[0052] Specifically, the optimization steps for the dimensions of the pulp distribution structure can be as follows:

[0053] Step 1 uses a simple fluid dynamics calculation model to calculate the optimized gradient orifice ratio of the flow equalizer, the length of buffer zone I, and the length of buffer zone II at a specified flow rate.

[0054] Specifically, the flow area ratio of each concentric circle on the flow equalization plate is determined by numerical calculation using fluid dynamics. The specific steps are as follows:

[0055] I. Establish fluid dynamics model 1, which includes the separator tank wall, a magnetic medium with a specified volume filling rate, inlet and outlet buffer zones, and inlet and outlet. The inlet flow rate is specified by the actual operating conditions.

[0056] 2. The velocity distribution along the radius V(r) at the interface between the buffer zone and the magnetic medium zone is calculated, where V represents the velocity, r represents the radius, 0≤r≤R, and R represents the inner radius of the separation tank.

[0057] III. Generally, the flow velocity is minimum at the wall of the separator. We take the flow velocity V0 closest to the wall and define the relative change in flow velocity relative to V0 at any radius r.

[0058]

[0059] If the flow area ratio on the wall of the separator is taken as ξ0, then the flow area ratio at any radius r is calculated by the following formula.

[0060] ξ(r)=[1-ζ(r)]ξ0 (1)

[0061] IV. Establish fluid dynamics model 2. Based on model 1, add a flow equalization plate. The flow area ratio on each concentric circle on the flow equalization plate satisfies equation (1). Calculate the velocity distribution V(r) along the radius at the interface between the buffer zone and the magnetic medium zone, as well as the maximum velocity V. max and minimum flow velocity V min .

[0062] V. If |V max -V min If |<ε, where ε is a user-defined small quantity, then the distribution of the circulation area ratio ξ(r) is the desired result. Otherwise, repeat steps three and four.

[0063] 6. Calculate the flow area ratio of each concentric circle on the flow equalization plate according to their respective radii, and then calculate the total area of ​​the holes on each concentric circle on the flow equalization plate.

[0064] Step 2 involves passing a standard non-metallic / metallic mineral sample into the actual equipment and comparing the difference in saturation time with other magnetic separation equipment of the same specifications to select the optimal value.

[0065] In this embodiment, as Figure 2 As shown, the flow equalization plate is alternately divided into three opening regions and two transition regions along the radial direction.

[0066] Furthermore, following the above method, the opening ratio of the three opening regions in this embodiment is determined, that is, the ratio of the total opening area of ​​the opening region to the area of ​​the region, which increases sequentially from the inside to the outside. The opening ratio of region I is 0.3, the opening ratio of region II is 0.55, and the opening ratio of region III is 0.65.

[0067] like Figures 5-10 The diagram shows the flow velocities of fluid in the separator tank with and without a flow equalizer. The flow velocity diagram using streamlines to represent the flow field better illustrates the vortices. Figure 5 , 7 The vortex is more pronounced in 9, and the flow velocity is uneven. Figure 6 , 8 After the flow equalization plate is used in step 10, the vortex is confined to a shorter area, and the flow velocity is more uniform. Therefore, it is shown that the flow equalization effect is significant after the flow equalization plate of the present invention is used in the separation tank of the present invention.

[0068] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions conceived without inventive effort should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A slurry high gradient magnetic separator separation tank comprising a magnetic medium packing zone and a pulp distribution structure symmetrically arranged on both sides of the magnetic medium packing zone, characterized in that, The slurry distribution structure includes a buffer zone I, a circular flow equalization plate, a buffer zone II, and a circular uniform perforation plate arranged sequentially. The buffer zone I consists of a frustum section on the outer side, which includes a slurry outlet or inlet, and a straight section on the inner side. The buffer zone II only contains the straight section. The flow equalization plate has holes formed by alternating radial elongated holes and adjacent annular opening areas. In the transition area between adjacent annular opening areas, the openings in the adjacent areas extend to the transition area in an arc shape to form a transition treatment. The flow equalization plate is alternately divided into n opening areas and (n-1) transition areas along the radial direction. The opening structure on the flow equalization plate is as follows: the openings in each area are evenly distributed along the circumference, and the openings in adjacent areas are staggered. The two sides of each hole are part of the radius of the circular plate. The sides of each hole maintain an arc transition. The openings in adjacent areas extend to the transition area in an arc shape.

2. The slurry high gradient magnetic separator separation tank of claim 1, wherein, The flow equalization plate is alternately divided into three opening regions and two transition regions along the radial direction.

3. The slurry high gradient magnetic separator separation tank of claim 1, wherein, The flow equalization plate is made of non-magnetic stainless steel.

4. A flow equalizing plate of circular configuration, characterized in that The flow equalization plate is provided with holes formed by alternating radial elongated holes and adjacent annular opening areas. In the transition area between adjacent annular opening areas, the openings of the adjacent areas extend to the transition area in an arc shape to form a transition treatment. The flow equalization plate is divided into n opening areas and (n-1) transition areas along the radial direction. The opening structure of the flow equalization plate is as follows: the openings in each area are evenly distributed along the circumference, and the openings in adjacent areas are staggered; the two sides of each hole are part of the radius of the circular plate; the sides of each hole maintain an arc transition; the openings of adjacent areas extend to the transition area in an arc shape.

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