Gravity separation and impurity removal system for processing low-grade bauxite

Abstract

The embodiment of the present application discloses a gravity separation and impurity removal system for processing low-grade bauxite, comprising: a crushing unit for crushing raw material to obtain crushed material; a pretreatment and grading unit for pretreating the crushed material and grading the crushed material after pretreatment according to a preset size to obtain a first particle size material and a second particle size material, wherein the particle size of the first particle size material is larger than that of the second particle size material; a first gravity separation unit for gravity separation and impurity removal of the first particle size material to obtain a first particle size gravity separation concentrate and a first particle size gravity separation tailings; a second gravity separation unit for gravity separation and impurity removal of the second particle size material to obtain a second particle size gravity separation concentrate and a second particle size gravity separation tailings; and a sedimentation and filtration unit for sedimentation and filtration of the second particle size gravity separation concentrate to obtain a dehydrated second particle size product. This setup produces aluminum concentrate with high alumina content, a high aluminum-silicon ratio, and relatively low impurity content, as well as tailings with high silica content. The entire system features low operating costs, a simple process, and no chemical agents are added during the entire gravity separation and impurity removal process. The concentrate is suitable for alumina production, and the tailings are used in the building materials industry. It can effectively reduce the ore consumption of alumina production from low-grade bauxite and reduce the amount of red mud.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of mineral processing, and in particular to a gravity separation and impurity removal system for processing low-grade bauxite. Background Art

[0002] With the increasing depletion of high-grade bauxite resources, the aluminum-silicon ratio of alumina enterprises has dropped significantly. The bauxite impurity removal technologies that have been industrialized are mainly high-sulfur bauxite flotation desulfurization technology and low-quality bauxite flotation desiliconization technology. Flotation technology has the disadvantages of high cost, complex process, high energy consumption of ore fine grinding and dissociation, and difficulty in storage and disposal due to residual reagents, fine particle size and high water content in the tailings. As a result, the profit margin of alumina enterprises using aluminum concentrate to produce alumina is relatively low, which seriously limits the industrialization and promotion of bauxite flotation desiliconization technology. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0004] To this end, the present invention provides a gravity separation and impurity removal system for processing low-grade bauxite.

[0005] In view of this, according to an embodiment of the present application, a gravity separation and impurity removal system for processing low-grade bauxite is proposed, comprising:

[0006] A crushing unit, used for crushing raw materials to obtain crushed materials;

[0007] a pre-treatment and grading unit for pre-treating the crushed material and grading the pre-treated crushed material according to a preset size to obtain a first-grade material and a second-grade material, wherein the particle size of the first-grade material is larger than that of the second-grade material;

[0008] The first gravity separation unit is used for gravity separation and impurity removal of the first particle size material to obtain the first particle size gravity separation concentrate and the first particle size gravity separation tailings;

[0009] The second gravity separation unit is used for gravity separation and impurity removal of the second size material to obtain the second size gravity separation concentrate and the second size gravity separation tailings;

[0010] The sedimentation filter press unit is used for sedimentation filter press-filtering the second-size gravity separation concentrate and the second-size gravity separation tailings to obtain a dehydrated second-size product.

[0011] In a feasible implementation, it further includes:

[0012] The medium recovery and reuse unit is used to process the product obtained after the first-grade material is re-selected and separated to obtain medium, and to recover and reuse the above medium.

[0013] In a feasible embodiment, the crushing unit includes:

[0014] jaw crushers, cone crushers, and rod mills;

[0015] Among them, the discharge port of the above-mentioned rod mill is the peripheral discharge of the end, and the rod body of the above-mentioned rod mill occupies 1 / 4 to 1 / 2 of the volume of the cavity of the above-mentioned rod mill; the liquid-solid ratio of the liquid in the cavity of the above-mentioned rod mill and the above-mentioned raw material is 0.4 to 0.65; the above-mentioned crushed material after processing by the above-mentioned rod mill is ore with a particle size of -3mm, and the material with a particle size of -3+0.5mm in the above-mentioned crushed material accounts for 50% to 65%.

[0016] In a feasible embodiment, the particle size of the first-grade material obtained after being processed by the pretreatment and classification unit is -n+0.5 mm, wherein n is the maximum particle size of the first-grade material, and the value of n ranges from 1 mm to 4 mm;

[0017] The particle size of the second-grade material obtained after being processed by the pretreatment and classification unit is -0.15 mm;

[0018] The material with a particle size of -0.5+0.15 mm obtained after being processed by the pretreatment and classification unit is returned to the rod mill for further grinding.

[0019] In a feasible implementation manner, the first reselection unit includes:

[0020] The first gravity separation impurity removal component and the second gravity separation impurity removal component are used to perform a primary gravity separation and impurity removal on the first particle size material to obtain a primary gravity separation concentrate and a first particle size gravity separation tailings; the primary gravity separation concentrate is subjected to a secondary gravity separation and impurity removal on the second gravity separation impurity removal component to obtain the first particle size gravity separation concentrate and a secondary gravity separation tailings, and the secondary gravity separation tailings are returned to the first gravity separation impurity removal component for further gravity separation and impurity removal.

[0021] In a feasible embodiment, the separation density of the first gravity separation and impurity removal component is 1.5 g / cm 3 to 1.9 / cm 3 , the feeding pressure is 0.08Mpa to 0.12Mpa;

[0022] The separation density of the secondary gravity separation and impurity removal operation of the second gravity separation and impurity removal component is 2.0g / cm 3 to 2.9 / cm 3 , the feeding pressure is 0.14Mpa to 0.2Mpa.

[0023] In a feasible embodiment, the first gravity separation and impurity removal component includes: a first heavy medium stirring barrel, a first slurry pump, a first heavy medium cyclone, and a first dual-channel de-medium washing screen; the second gravity separation and impurity removal component includes: a second heavy medium stirring barrel, a second slurry pump, a second heavy medium cyclone, and a second dual-channel de-medium washing screen;

[0024] During the primary gravity separation and impurity removal process, the first-grade material enters the first heavy medium mixing barrel and is pumped into the first heavy medium cyclone through the first slurry pump. The overflow and underflow of the first heavy medium cyclone pass through the first dual-channel de-medium washing screen to separate the medium. The ore on the overflow screen of the first heavy medium cyclone is the first-grade gravity separation tailings, and the ore on the underflow screen of the first heavy medium cyclone is the primary gravity separation concentrate.

[0025] During the secondary gravity separation and impurity removal process, the primary gravity separation concentrate enters the second heavy medium mixing barrel and is pumped into the second heavy medium cyclone through the second slurry pump. After the overflow and underflow of the second heavy medium cyclone pass through the second double-channel de-medium washing screen to separate the medium, the ore on the underflow screen of the second heavy medium cyclone is the first-size gravity separation concentrate, and the ore on the overflow screen of the second heavy medium cyclone is the secondary gravity separation tailings, which returns to the first heavy medium mixing barrel to repeat the primary gravity separation and impurity removal process.

[0026] In one feasible embodiment, the first heavy medium cyclone and the second heavy medium cyclone constitute a two-stage series heavy medium cyclone, wherein the angle between the placement angle of the two-stage series heavy medium cyclone and the horizontal plane is 15° to 20°; the cone angle of the two-stage series heavy medium cyclone is 20° to 40°; the bottom flow port diameter of the two-stage series heavy medium cyclone is 20mm to 30mm; the overflow port diameter of the two-stage series heavy medium cyclone is 60mm to 70mm; and the center overflow pipe length of the two-stage series heavy medium cyclone is 300mm to 450mm.

[0027] Wherein, the diameter of the underflow port of the second heavy medium cyclone is smaller than the diameter of the underflow port of the first heavy medium cyclone.

[0028] In a feasible implementation manner, the second reselection unit includes:

[0029] A double-drum centrifugal concentrator is provided with a first drum body and a second drum body, wherein the inclined surfaces of the first drum body and the second drum body are inclined at an angle of 2° to 8°, wherein the first drum body is used to perform a primary centrifugal impurity removal on the second particle size to obtain a primary impurity-removed tailing and a primary impurity-removed concentrate; and the second drum body is used to perform a secondary centrifugal impurity removal on the primary impurity-removed tailing to obtain a second particle size gravity-removed tailing and a secondary impurity-removed concentrate, wherein the primary impurity-removed concentrate and the secondary impurity-removed concentrate are combined into a second particle size gravity-removed concentrate.

[0030] Wherein, the diameter of the first rotating drum body is smaller than the diameter of the second rotating drum body.

[0031] In a feasible embodiment, the heavy medium used in the first gravity selection unit includes ferrosilicon powder and magnet powder, the ratio of the ferrosilicon powder to the magnet powder is 1:3, and the particle size of the ferrosilicon powder and the magnet powder is less than 0.038 mm.

[0032] Compared to the prior art, the present invention has at least the following beneficial effects: The gravity separation and impurity removal system for processing low-grade bauxite provided in the embodiments of the present application includes a crushing unit, a pretreatment and classification unit, a first gravity separation unit, a second gravity separation unit, and a sedimentation and filtration unit. The crushing unit is used to crush the raw material to obtain a crushed material. The crushed material is then cleaned and pretreated by the pretreatment and classification unit, and the pretreated crushed material is then graded according to a preset size to obtain a first-grade material and a second-grade material, wherein the particle size of the first-grade material is larger than that of the second-grade material. The first-grade material is gravity-separated and impurity-removed by the first gravity separation unit to obtain a first-grade gravity separation concentrate and a first-grade gravity separation tailings. The second-grade material is gravity-separated and impurity-removed by the second gravity separation unit to obtain a second-grade gravity separation concentrate and a second-grade gravity separation tailings. The second-grade gravity separation concentrate and the second-grade gravity separation tailings are subjected to sedimentation and filtration by the sedimentation and filtration unit to obtain a dehydrated second-grade product. The gravity separation and impurity removal system for processing low-grade bauxite provided in this application can produce aluminum concentrate with high alumina content, high aluminum-silicon ratio, and relatively low impurity content, as well as tailings with high silica content. The entire system has low operating costs, a simple process, and no chemical agents are added during the entire gravity separation and impurity removal process. The concentrate is suitable for producing alumina, and the tailings are used in the building materials industry. It can effectively reduce the ore consumption of alumina production from low-grade bauxite and reduce the amount of red mud. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0034] Figure 1 This is a schematic diagram of the architecture of a gravity separation and impurity removal system for processing low-grade bauxite according to an embodiment of the present application;

[0035] Figure 2 A schematic structural diagram of a system for gravity separation and impurity removal of low-grade bauxite according to an embodiment of the present application;

[0036] Figure 3 A schematic structural diagram of a first dense medium cyclone according to an embodiment of the present application;

[0037] Figure 4 A schematic structural diagram of a first dual-channel media removal and washing screen according to an embodiment of the present application, viewed from one angle;

[0038] Figure 5 This is a schematic structural diagram of the first dual-channel media removal and washing screen according to an embodiment of the present application from another angle;

[0039] Figure 6 A schematic structural diagram of a double-drum centrifugal concentrator according to an embodiment of the present application, viewed from one angle;

[0040] Figure 7 This is a schematic structural diagram from another angle of a double-drum centrifugal concentrator according to an embodiment of the present application.

[0041] in, Figures 1 to 7 The corresponding relationship between the reference numerals and component names is as follows:

[0042] 100 Crushing unit, 101 Crusher, 102 Rod mill, 200 Pretreatment and classification unit, 201 Storage tank, 203 Raw material slurry pump, 204 3mm linear screen, 205 Ore washing equipment, 206 0.5mm grading linear screen, 207 High-frequency rotary vibrating screen, 300 First gravity separation unit, 301 First heavy medium mixing barrel, 302 First slurry pump, 303 First heavy medium cyclone, 304 First dual-channel de-medium washing screen, De-medium zone A, Washing zone B, Dehydration zone C, 3041 De-medium discharge port, 3042 Washing zone, 3043 Partition, 3044 Overflow feed port, 3045 Underflow feed port, 3046 Overflow discharge port, 3047 Underflow discharge port, 3048 Spray pipe, 305 Second heavy medium mixing barrel, 306 Second slurry pump, 307 Second heavy medium cyclone, 3 08 second dual-channel media removal and washing screen, 400 second gravity separation unit, 401 feeding mixing drum, 402 double-drum centrifugal concentrator, 4021 first drum body, 4022 second drum body, 403 automatic control cabinet, 404 second-grade tailings mixing drum, 405 second-grade tailings slurry pump, 406 second-grade concentrate mixing drum, 407 second-grade concentrate slurry pump, 408 drum pump, 500 media recovery and reuse unit, 501 first magnetic separator, 502 second magnetic separator, 600 sedimentation filter press unit, 601 second-grade gravity separation tailings sedimentation tank, 602 second-grade gravity separation concentrate sedimentation tank. DETAILED DESCRIPTION

[0043] In order to better understand the above technical solution, the technical solution of the embodiment of the present application is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiment of the present application and the specific features in the embodiment are detailed descriptions of the technical solution of the embodiment of the present application, rather than limitations on the technical solution of the present application. In the absence of conflict, the embodiment of the present application and the technical features in the embodiment can be combined with each other.

[0044] like Figures 1 to 7 As shown, according to an embodiment of the present application, a gravity separation and impurity removal system for processing low-grade bauxite is proposed, comprising: a crushing unit 100 for crushing raw materials to obtain crushed materials;

[0045] The pretreatment and grading unit 200 is used to pretreat the above-mentioned crushed material, and grade the above-mentioned crushed material after pretreatment according to a preset size to obtain a first particle size material and a second particle size material, wherein the particle size of the above-mentioned first particle size material is larger than the particle size of the above-mentioned second particle size material; the first gravity separation unit 300 is used to gravity-select and remove impurities from the above-mentioned first particle size material to obtain a first particle size gravity separation concentrate and a first particle size gravity separation tailings; the second gravity separation unit 400 is used to gravity-select and remove impurities from the above-mentioned second particle size material to obtain a second particle size gravity separation concentrate and a second particle size gravity separation tailings; the sedimentation and filtration unit 600 is used to sediment and filter the above-mentioned second particle size gravity separation concentrate and the above-mentioned second particle size gravity separation tailings to obtain a dehydrated second particle size product.

[0046] It is understood that the gravity separation and impurity removal system for processing low-grade bauxite provided in the embodiment of the present application includes a crushing unit 100, a pretreatment and classification unit 200, a first gravity separation unit 300, a second gravity separation unit 400, and a sedimentation and filtration unit 600. Among them, the crushing unit 100 is used to crush the raw material to obtain crushed material. Subsequently, the crushed material is cleaned and pre-treated by the pretreatment and classification unit 200, and the pre-treated crushed material is classified according to a preset size to obtain a first particle size material and a second particle size material, wherein the particle size of the first particle size material is larger than that of the second particle size material. The first particle size material is gravity separated and impurities removed by the first gravity separation unit 300 to obtain a first particle size gravity separation concentrate and a first particle size gravity separation tailings; the second particle size material is gravity separated and impurities removed by the second gravity separation unit 400 to obtain a second particle size gravity separation concentrate and a second particle size gravity separation tailings. The second-grade gravity separation concentrate and the second-grade gravity separation tailings are subjected to sedimentation and pressure filtration by the sedimentation and pressure filter unit 600 to obtain a dehydrated second-grade product. The gravity separation and impurity removal system for processing low-grade bauxite provided in this application can obtain aluminum concentrate with a high alumina content, a high aluminum-silicon ratio, and a relatively low impurity content, and tailings with a high silica content. The entire system has low operating costs, a simple process, and no chemical agents are added during the entire gravity separation and impurity removal process. The concentrate is suitable for producing alumina, and the tailings are used in the building materials industry. It can effectively reduce the ore consumption of low-grade bauxite in producing alumina and reduce the amount of red mud.

[0047] It should be noted that low-grade bauxite has an alumina content of 50% to 55%, a silica content of 20% or more, an illite content of 20% or more in the raw ore, and an aluminum-silicon ratio of 2.0 to 2.75. For example, the selected low-grade bauxite has an alumina content of 53.56%, a silica content of 21.36%, an illite content of 23% in the raw ore, and an aluminum-silicon ratio of 2.50.

[0048] It is understandable that the pre-treatment and classification unit 200 may be provided with a storage tank 201, a raw material slurry pump 203, a 3mm linear screen 204, a ore washing device 205, a 0.5mm grading linear screen 206, and a high-frequency rotary vibrating screen 207. After the raw material is crushed by the crushing unit 100, it can be placed in the storage tank 201 and then pumped into the 3mm linear screen 204 for classification by the raw material slurry pump 203. The ore on the screen has a larger particle size and needs to be returned to the crushing unit 100 for further processing. The ore under the screen enters the ore washing device 205 for cleaning. After cleaning, the ore under the screen enters the 0.5mm grading linear screen 206 for classification. The ore with a particle size of -3+0.5mm enters the first gravity separation unit 300; the material with a particle size less than 0.5mm enters the high-frequency rotary vibrating screen 207 for classification. The ore with a particle size of -5+0.15mm is ground again by the rod mill 102, and the ore with a particle size of -0.15mm enters the second gravity separation unit 400.

[0049] It should be noted that the sedimentation filter press unit 600 can send the second-grade gravity separation concentrate into the second-grade gravity separation concentrate sedimentation tank 602, and send the second-grade gravity separation tailings into the second-grade gravity separation tailings sedimentation tank 601, which are then pumped into the plate filter press after a period of sedimentation to form a filter cake.

[0050] In some examples, such as Figure 1 and Figure 2 As shown, it also includes: a medium recovery and reuse unit 500, which is used to process the product obtained after the first particle size material is re-selected and separated to obtain medium, and recover and reuse the above medium.

[0051] It is understood that when performing gravity separation and impurity removal operations on the first-grade material, the first gravity separation unit 300 requires the use of a heavy medium. The heavy medium can be a suspension of water, ferrosilicon powder, and magnetic powder. The density of the suspension can be determined according to the process flow. The medium recovery and reuse unit 500 can be equipped with a heavy medium recovery magnetic separator. After the material is de- and washed in the first gravity separation unit 300, the de- and washed medium can be reused by the heavy medium recovery magnetic separator or re-entered into the heavy medium mixing barrel of the first gravity separation unit 300 for use, thereby reducing raw material damage and saving costs.

[0052] In some examples, such as Figure 2 As shown, the crushing unit 100 includes: a jaw crusher 101, a cone crusher 101 and a rod mill 102; wherein, the discharge port of the rod mill 102 is the peripheral discharge of the end, and the rod body of the rod mill 102 occupies 1 / 4 to 1 / 2 of the volume of the cavity of the rod mill 102; the liquid-solid ratio of the liquid in the cavity of the rod mill 102 and the raw material is 0.4 to 0.65; the crushed material after being processed by the rod mill 102 is ore with a particle size of -3mm, and the material with a particle size of -3+0.5mm accounts for 50% to 65% of the crushed material.

[0053] It can be understood that the crushing unit 100 can be provided with a jaw crusher 101, a cone crusher 101 and a rod mill 102 to gradually reduce the particle size of the material. The crushed material after being processed by the final rod mill 102 is ore with a particle size of -3 mm, and the material with a particle size of -3+0.5 mm accounts for 50% to 65% of the crushed material.

[0054] It should be noted that the specific value of the maximum ore crushing particle size can be determined based on the basic properties of the selected ore and through process mineralogy research. The value of the maximum ore crushing particle size can directly affect the effect of gravity separation. By determining the maximum ore crushing particle size, the number of steel rods in the rod mill 102 and the liquid-to-solid ratio can be adjusted.

[0055] For example, the maximum crushing particle size of the ore is 3 mm, the volume of the steel rod is 2 / 5 of the volume of the rod mill 102 cavity, the liquid-solid ratio is 0.55, and the proportion of -3+0.5 mm in this material is 60%.

[0056] In some examples, the particle size of the first particle size material obtained after being processed by the above-mentioned pretreatment and grading unit 200 is -n+0.5mm, wherein n is the maximum particle size of the above-mentioned first particle size material, and the value range of n is 1mm to 4mm; the particle size of the second particle size material obtained after being processed by the above-mentioned pretreatment and grading unit 200 is -0.15mm; wherein, the material with a particle size of -0.5+0.15mm obtained after being processed by the above-mentioned pretreatment and grading unit 200 is returned to the above-mentioned rod mill 102 for re-grinding, so as to improve the grading accuracy of the first particle size material and the second particle size material, avoid misclassification, and reduce raw material waste.

[0057] For example, n can be 3, the first particle size is -3+0.5 mm, accounting for 60%; the second particle size is -0.15 mm, accounting for 40%.

[0058] In some examples, such as Figures 1 to 3 As shown, the first gravity separation unit 300 includes: a first gravity separation impurity removal component and a second gravity separation impurity removal component. The first size material is subjected to a first gravity separation and impurity removal separation by the first gravity separation and impurity removal component to obtain a first gravity separation concentrate and a first size gravity separation tailings; the first gravity separation concentrate is subjected to a second gravity separation and impurity removal separation by the second gravity separation and impurity removal component to obtain the first size gravity separation concentrate and a second gravity separation tailings. The second gravity separation tailings are returned to the first gravity separation and impurity removal component for another gravity separation and impurity removal.

[0059] It is understandable that the first gravity separation unit 300 may be provided with a first gravity separation impurity removal component and a second gravity separation impurity removal component, and the screening particle size of the first gravity separation unit 300 is greater than the screening particle size of the second gravity separation unit 400. Among them, the first-grade material separated by the pretreatment classification unit 200 may first be subjected to a first gravity separation and impurity removal by the first gravity separation component to obtain a first-grade gravity separation concentrate and a first-grade gravity separation tailings, so as to realize the roughing process. After the roughing is completed, the first-grade gravity separation concentrate is subjected to a second gravity separation and impurity removal by the second gravity separation component to obtain a first-grade gravity separation concentrate and a second gravity separation tailings, and the second gravity separation tailings are re-introduced into the first gravity separation impurity removal component for further processing. Through the roughing and concentrating process, the grade and recovery rate of the first-grade concentrate can be guaranteed, and the utilization rate of low-grade bauxite can be improved. It can also better achieve the separation of aluminum minerals and impurity minerals.

[0060] In some examples, the separation density of the first gravity separation and impurity removal component is 1.5 g / cm 3 to 1.9 / cm 3 The feeding pressure is 0.08Mpa to 0.12Mpa; the separation density of the secondary gravity separation and impurity removal operation of the above-mentioned second gravity separation and impurity removal component is 2.0g / cm 3 to 2.9 / cm 3 , the feeding pressure is 0.14Mpa to 0.2Mpa.

[0061] It is understandable that the sorting density of the primary gravity separation and impurity removal operation is lower than the sorting density of the secondary gravity separation and impurity removal operation of the second gravity separation and impurity removal component, and the loading pressure of the primary gravity separation and impurity removal operation is lower than the loading pressure of the secondary gravity separation and impurity removal operation. The above-mentioned settings of the sorting density and loading pressure can realize the roughing and concentrating process flow, ensure the grade and recovery rate of the first-grade concentrate, improve the utilization rate of low-grade bauxite, and better achieve the separation of aluminum minerals and impurity minerals.

[0062] For example, the separation density of a gravity separation operation is 1.85g / cm 3 The feeding pressure is 0.1Mpa; the separation density of the secondary gravity separation and impurity removal operation is 2.0g / cm 3 , the feeding pressure is 0.16Mpa.

[0063] In some examples, such as Figures 2 to 5As shown, the first re-selection impurity removal component includes: a first heavy medium stirring barrel 301, a first slurry pump 302, a first heavy medium cyclone 303, and a first dual-channel de-medium washing screen 304; the second re-selection impurity removal component includes: a second heavy medium stirring barrel 305, a second slurry pump 306, a second heavy medium cyclone 307, and a second dual-channel de-medium washing screen 308; during the above-mentioned one-time re-selection impurity removal operation, the first-grade material enters the first heavy medium stirring barrel 301, and is pumped into the first heavy medium cyclone 303 through the first slurry pump 302. The overflow and underflow of the first heavy medium cyclone 303 pass through the first dual-channel de-medium washing screen 304 to separate the medium and remain in the first heavy medium cyclone 303. The overflow oversize ore is the first-size gravity-separated tailings, and the underflow oversize ore remaining in the first heavy medium cyclone 303 is the primary gravity-separated concentrate. During the secondary gravity-separation and impurity removal process, the primary gravity-separated concentrate enters the second heavy medium stirring barrel 305, and is pumped into the second heavy medium cyclone 307 through the second slurry pump 306. After the overflow and underflow of the second heavy medium cyclone 307 pass through the second dual-channel de-mediating and washing screen 308 to separate the medium, the underflow oversize ore remaining in the second heavy medium cyclone 307 is the first-size gravity-separated concentrate, and the overflow oversize ore remaining in the second heavy medium cyclone 307 is the secondary gravity-separated tailings, which return to the first heavy medium stirring barrel 301 to repeat the primary gravity-separation and impurity removal process.

[0064] It is understood that the first gravity separation and impurity removal component can be provided with a first heavy medium stirring barrel 301, a first slurry pump 302, a first heavy medium cyclone 303, and a first dual-channel de-medium washing screen 304. Specifically, when performing a gravity separation and impurity removal operation, a first heavy medium suspension can be prepared first, and then the first particle size material can be put into the first heavy medium stirring barrel 301, and then pumped into the first heavy medium cyclone 303 by the first slurry pump 302, and screened by the first heavy medium cyclone 303. The first heavy medium cyclone 303 is connected to the first dual-channel de-medium washing screen 304, wherein the overflow of the first heavy medium cyclone 303 enters the first dual-channel de-medium washing screen 304 through the overflow feed port 3044; the underflow of the first heavy medium cyclone 303 enters the first dual-channel de-medium washing screen 304 through the underflow feed port 3045, and then passes through the first dual-channel de-medium washing screen 304 for de-medium washing. The overflow ore on the screen after the de-medium washing operation is completed is output through the overflow discharge port 3046. The processed overflow ore on the screen is the first-grade gravity separation tailings. The underflow ore on the screen after the de-medium washing operation is completed is output through the underflow discharge port 3047. The underflow ore on the screen remaining in the first heavy medium cyclone 303 after processing is the primary gravity separation concentrate, thereby realizing the coarse screening operation of the first-grade material.

[0065] It is understood that the secondary gravity separation and impurity removal assembly may be provided with a second heavy medium agitation drum 305, a second slurry pump 306, a second heavy medium cyclone 307, and a second dual-channel de-mediation and washing screen 308. Specifically, during the secondary gravity separation and impurity removal operation, a second heavy medium suspension may be prepared first, and then the primary gravity separation concentrate may be added to the first heavy medium agitation drum 301. The concentrate is then pumped into the second heavy medium cyclone 307 via the second slurry pump 306, where it is screened by the second heavy medium cyclone 307. The second heavy medium cyclone 307 is connected to the second dual-channel de-mediation and washing screen 308. The overflow and underflow of the second heavy medium cyclone 307 are respectively de-mediated and washed by the second dual-channel de-mediation and washing screen 308. The processed overflow oversize ore is the secondary gravity separation tailings, and the underflow oversize ore remaining in the first heavy medium cyclone 303 is the first-grade gravity separation concentrate, thereby achieving fine screening of the first-grade material. The secondary gravity separation tailings need to be re-entered into the first gravity separation impurity removal component for coarse screening, and then into the second gravity separation impurity removal component for fine screening to ensure the grade and recovery rate of the first-grade concentrate, improve the utilization rate of low-grade bauxite, and better separate aluminum minerals from impurity minerals.

[0066] It should be noted that the density of the first heavy medium suspension is less than the density of the second heavy medium suspension.

[0067] It should be noted that if Figure 4 and Figure 5 As shown, the first dual-channel de-medium washing screen 304 is equipped with two under-screen outlets: a de-medium outlet 3041 and a washing outlet 3042. The suspension flowing out of the de-medium outlet 3041 can be directly returned to the heavy medium mixing tank. The washing outlet 3042 discharges the heavy medium and water attached to the product after spraying, flows into the heavy medium recovery magnetic separator to recover the heavy medium, and then returns to the heavy medium mixing tank for reuse. The screen surface is provided with a partition 3043, the position of which can be adjusted according to the basic properties of the ore. The first dual-channel de-medium washing screen 304 and the second dual-channel de-medium washing screen 308 can use the same structure.

[0068] Exemplarily, the layout of the double-channel de-mediation and washing screen has a screen surface length of 4m. From the feed section to 2m is the de-mediation zone A, from 2m to 3.5m is the washing zone B, and multiple spray pipes 3048 are added to the upper end of the washing zone B. The specific number depends on the on-site effect. From 3.5m to 4m is the dehydration zone C.

[0069] In some examples, the first heavy medium cyclone 303 and the second heavy medium cyclone 307 constitute a two-stage series heavy medium cyclone, and the angle between the placement angle of the two-stage series heavy medium cyclone and the horizontal plane is 15° to 20°; the cone angle of the two-stage series heavy medium cyclone is 20° to 40°; the bottom flow port diameter of the two-stage series heavy medium cyclone is 20mm to 30mm; the overflow port diameter of the two-stage series heavy medium cyclone is 60mm to 70mm; the central overflow pipe length of the two-stage series heavy medium cyclone is 300mm to 450mm; wherein, the bottom flow port diameter of the second heavy medium cyclone 307 is smaller than the bottom flow port diameter of the first heavy medium cyclone 303.

[0070] It is understood that the first heavy medium cyclone 303 and the second heavy medium cyclone 307 can constitute a two-stage series heavy medium cyclone, so that the first heavy medium cyclone 303's underflow screen can be quickly fed into the second heavy medium cyclone 307, shortening the process route and improving efficiency. Furthermore, the first heavy medium cyclone 303 and the second heavy medium cyclone 307 both form an angle with the horizontal plane to achieve better sorting results. The overflow port diameter and center overflow pipe length of the first and second heavy medium cyclones 303 and 307 can be identical, and the underflow port diameter of the second heavy medium cyclone 307 is smaller than that of the first heavy medium cyclone 303 to ensure that the second heavy medium cyclone 307 has higher screening accuracy and the grade of the first-size concentrate.

[0071] For example, Figure 3 As shown, the first dense medium cyclone 303 is placed at an angle of 20° to the horizontal plane, the bottom flow port diameter is 25 mm, the overflow port diameter is 60 mm, and the center overflow pipe length is 400 mm.

[0072] In some examples, such as Figure 6 and Figure 7 As shown, the second gravity separation unit 400 includes: a double-drum centrifugal concentrator 402, which is provided with a first drum body 4021 and a second drum body 4022, and the inclination angles of the inclined surfaces of the first drum body 4021 and the second drum body 4022 are 2° to 8°. The first drum body 4021 is used to perform a primary centrifugal impurity removal on the second particle size to obtain a primary impurity-removed tailing and a primary impurity-removed concentrate; the second drum body 4022 is used to perform a secondary centrifugal impurity removal on the primary impurity-removed tailing to obtain a second particle size gravity separation tailing and a secondary impurity-removed concentrate, wherein the primary impurity-removed concentrate and the secondary impurity-removed concentrate are combined into a second particle size gravity separation concentrate; wherein the diameter of the first drum body 4021 is smaller than the diameter of the second drum body 4022.

[0073] It is understood that the second gravity separation unit 400 is provided with a feed mixing barrel 401, a double-drum centrifugal concentrator 402, a second-size tailings mixing barrel 404, a second-size tailings slurry pump 405, a second-size concentrate mixing barrel 406, a second-size concentrate slurry pump, and a barrel pump 408. The second-size material can be pumped into the feed mixing barrel 401 by the barrel pump 408 and enter the double-drum centrifugal concentrator 402 by gravity. The second-size material will first flow into the first drum body 4021 for primary centrifugal cleaning. After the primary centrifugal cleaning, the tailings will flow into the second drum body 4022 for secondary centrifugal cleaning. The tailings after the secondary centrifugal cleaning will flow out directly as the second-size centrifugal tailings. After the ore is cut off, the flushing water is turned on to flush out the primary centrifugal concentrate attached to the side walls of the first drum body 4021 and the secondary centrifugal concentrate on the side walls of the second drum body 4022, and merge them into the second-size centrifugal concentrate. The second-grade centrifugal tailings flow into the second-grade tailings mixing tank 404, where they are pumped into the sedimentation filter press unit 600 for sedimentation filtration via the second-grade tailings slurry pump 405. The second-grade centrifugal concentrate flows into the second-grade concentrate mixing tank 406, where they are pumped into the sedimentation filter press unit 600 for sedimentation filtration via the second-grade concentrate slurry pump.

[0074] It should be noted that the inclination angle of the inclined surfaces of the first rotating drum body 4021 and the second rotating drum body 4022 is 2° to 8°, and the inclination angle of the first rotating drum body 4021 is greater than the inclination angle of the inclined surface of the second rotating drum body 4022. For example, the inclination angle of the first rotating drum body 4021 is 6°, and the inclination angle of the inclined surface of the second rotating drum body 4022 is 2°.

[0075] It is understandable that the double-drum centrifugal concentrator 402 can also be provided with a feed port, an automatic control cabinet 403, a discharge port, a flushing water pipe, a rinsing water pipe and an automatic control cabinet 403. Among them, the automatic control cabinet 403 can be used to control the drum frequency of the first drum body 4021 and the second drum body 4022, with a control range of 20Hz to 40Hz; control the amount of rinsing water to be 300L / h to 500L / h; and an automated program is set up under the automatic control, which is divided into the initial stage, the ore feeding stage, the ore cutting stage, the flushing stage and the end stage. The operating time can be set for each stage. The initial stage only appears once each time the machine is turned on, and the process is cyclical in this order. Setting the drum frequency and the amount of rinsing water can directly affect the effect of the centrifugal concentrator's gravity separation and impurity removal; setting the time for each stage can increase the equipment's processing capacity without affecting the gravity separation effect. The feed port and the discharge port are connected to the cylinder, the air pump and the air compressor to realize automatic control. Specifically, when entering the feeding stage, the feed port will swing toward the feed port, and the discharge port will swing toward the tailings discharge port. The material will flow into the centrifugal concentrator for sorting, and the tailings will flow out immediately; when entering the ore-breaking stage, the feed port will swing toward the circulation return port, and the material will be pumped back to the feeding mixing barrel 401 through the barrel pump 408 for circulation. After the preset time, the drum frequency will automatically decrease to 10hz; when entering the flushing stage, the discharge port will quickly swing toward the concentrate discharge port, and the flushing water solenoid valve will open; when the system enters the end stage, the drum frequency will automatically increase to the set value; the feeding method is gravity feeding, and the feeding amount can be controlled by adjusting the valve size.

[0076] For example, the automatic control cabinet 403 can control the rotation frequency of the first drum body 4021 and the second drum body 4022 to 30Hz, control the amount of rinsing water to 400L / h, and the five stage setting times of the automation program are 10s, 30s, 6s, 10s and 5s respectively.

[0077] In some examples, the heavy medium used in the first re-selection unit 300 includes ferrosilicon powder and magnet powder, the ratio of the ferrosilicon powder to the magnet powder is 1:3, and the particle size of the ferrosilicon powder and the magnet powder is less than 0.038 mm.

[0078] It can be understood that the heavy medium recovery magnetic separator can be provided with a first magnetic separator 501 and a second magnetic separator 502, wherein the first magnetic separator 501 is used to recover the heavy medium of the first gravity separation concentrate and the first particle size gravity separation tailings; the second magnetic separator 502 is used to recover the heavy medium of the first particle size gravity separation concentrate and the secondary gravity separation tailings.

[0079] For example, when the selected low-grade bauxite had an alumina content of 53.56%, a silica content of 21.36%, an illite content of 23%, and an aluminum-silicon ratio of 2.50, the above exemplary parameters yielded a first-grade concentrate with a yield of 40.10%, an alumina content of 66.65%, and an aluminum-silicon ratio of 7.61; and a second-grade concentrate with a yield of 11.15%, an alumina content of 59.36%, and an aluminum-silicon ratio of 5.31, achieving efficient utilization of low-grade bauxite. The specific experimental results are shown in Table 1, where A / S is the aluminum-silicon ratio.

[0080] Table 1 Test results of Example 1

[0081] product Yield / % <![CDATA[Al2O3 / %]]> <![CDATA[SiO2 / %]]> <![CDATA[Fe2O3 / %]]> A / S Coarse-grained concentrate 40.10 66.65 8.76 7.61 7.61 Coarse tailings 33.08 38.50 33.15 1.16 1.16 Fine-grained concentrate 11.15 59.36 11.19 4.85 5.31 Fine tailings 15.67 35.48 28.72 1.23 1.24 raw ore 100.00 51.64 20.23 4.17 2.55

[0082] In the present invention, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The term "plurality" refers to two or more, unless expressly limited otherwise. Terms such as "installed," "connected," "connected," and "fixed" should be interpreted broadly. For example, "connected" can mean a fixed connection, a detachable connection, or an integral connection; "connected" can mean a direct connection or an indirect connection through an intermediary. Those skilled in the art will understand the specific meanings of these terms in the present invention based on specific circumstances.

[0083] In the description of the present invention, it should be understood that the directions or positional relationships indicated by terms such as "up", "down", "left", "right", "front" and "back" are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or unit referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the present invention.

[0084] Throughout this specification, terms such as "one embodiment," "some embodiments," and "specific embodiments" mean that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0085] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A gravity separation and impurity removal system for processing low-grade bauxite, characterized in that: include: A crushing unit, used for crushing raw materials to obtain crushed materials; a pretreatment and grading unit, configured to pretreatment the crushed material and grade the crushed material after pretreatment according to a preset size to obtain a first-grade material and a second-grade material, wherein the particle size of the first-grade material is larger than the particle size of the second-grade material; a first gravity separation unit for gravity separation and impurity removal of the first size material to obtain a first size gravity separation concentrate and a first size gravity separation tailings; the first gravity separation unit includes a first gravity separation impurity removal component and a second gravity separation impurity removal component; the first size material is subjected to a first gravity separation and impurity removal by the first gravity separation impurity removal component to obtain a first gravity separation concentrate and a first size gravity separation tailings; the first gravity separation concentrate is subjected to a second gravity separation and impurity removal by the second gravity separation impurity removal component to obtain a first size gravity separation concentrate and a second gravity separation tailings; the second gravity separation tailings are returned to the first gravity separation impurity removal component for further gravity separation and impurity removal; The second gravity separation unit is used for gravity separation and impurity removal of the second particle size material to obtain a second particle size gravity separation concentrate and a second particle size gravity separation tailings; A sedimentation filter press unit, used for sedimentation and filter pressing the second-size gravity separation concentrate and the second-size gravity separation tailings to obtain a dehydrated second-size product; The separation density of the first gravity separation and impurity removal component in a gravity separation and impurity removal operation is 1.5g / cm 3 to 1.9 / cm 3 , the feeding pressure is 0.08Mpa to 0.12Mpa; The separation density of the secondary gravity separation and impurity removal operation of the second gravity separation and impurity removal component is 2.0g / cm 3 to 2.9 / cm 3 , the feeding pressure is 0.14Mpa to 0.2Mpa.

2. The system for gravity separation and impurity removal of low-grade bauxite according to claim 1, characterized in that: Also includes: The medium recovery and reuse unit is used to process the product obtained after the first-grade material is re-selected and separated to obtain medium, and to recover and reuse the medium.

3. The system for gravity separation and impurity removal of low-grade bauxite according to claim 1, characterized in that: The crushing unit comprises: jaw crushers, cone crushers, and rod mills; Among them, the rod mill discharge port is the peripheral discharge of the end, and the rod body of the rod mill occupies 1 / 4 to 1 / 2 of the volume of the cavity of the rod mill; the liquid-solid ratio of the liquid in the cavity of the rod mill and the raw material is 0.4 to 0.65; the crushed material after processing by the rod mill is ore with a particle size of -3mm, and the material with a particle size of -3+0.5mm accounts for 50% to 65% of the crushed material.

4. The system for gravity separation and impurity removal of low-grade bauxite according to claim 3 is characterized in that: The particle size of the first-grade material obtained after being processed by the pretreatment and classification unit is -n+0.5 mm, wherein n is the maximum particle size of the first-grade material, and the value range of n is 1 mm to 4 mm; The particle size of the second-grade material obtained after being processed by the pretreatment and classification unit is -0.15 mm; The material with a particle size of -0.5+0.15 mm obtained after being processed by the pretreatment and classification unit is returned to the rod mill for further grinding.

5. The system for gravity separation and impurity removal of low-grade bauxite according to claim 4 is characterized in that: The first gravity separation and impurity removal assembly includes: a first heavy medium stirring barrel, a first slurry pump, a first heavy medium cyclone, and a first dual-channel de-medium washing screen; the second gravity separation and impurity removal assembly includes: a second heavy medium stirring barrel, a second slurry pump, a second heavy medium cyclone, and a second dual-channel de-medium washing screen; During the primary gravity separation and impurity removal process, the first-size material enters the first heavy medium mixing barrel and is pumped into the first heavy medium cyclone by the first slurry pump. After the overflow and underflow of the first heavy medium cyclone pass through the first dual-channel de-mediation and washing screen to separate the medium, the ore on the overflow screen of the first heavy medium cyclone is the first-size gravity separation tailings, and the ore on the underflow screen of the first heavy medium cyclone is the primary gravity separation concentrate. During the secondary gravity separation and impurity removal process, the primary gravity separation concentrate enters the second heavy medium stirring barrel and is pumped into the second heavy medium cyclone through the second slurry pump. After the overflow and underflow of the second heavy medium cyclone pass through the second double-channel de-mediation and washing screen to separate the medium, the ore on the underflow screen of the second heavy medium cyclone is the first particle size gravity separation concentrate, and the ore on the overflow screen of the second heavy medium cyclone is the secondary gravity separation tailings, which returns to the first heavy medium stirring barrel to repeat the primary gravity separation and impurity removal process.

6. The system for gravity separation and impurity removal of low-grade bauxite according to claim 5, characterized in that: The first heavy medium cyclone and the second heavy medium cyclone constitute a two-stage series heavy medium cyclone. The angle between the placement angle of the two-stage series heavy medium cyclone and the horizontal plane is 15° to 20°; the cone angle of the two-stage series heavy medium cyclone is 20° to 40°; the bottom flow port diameter of the two-stage series heavy medium cyclone is 20mm to 30mm; the overflow port diameter of the two-stage series heavy medium cyclone is 60mm to 70mm; and the center overflow pipe length of the two-stage series heavy medium cyclone is 300mm to 450mm. The diameter of the bottom flow port of the second heavy medium cyclone is smaller than the diameter of the bottom flow port of the first heavy medium cyclone.

7. The system for gravity separation and impurity removal of low-grade bauxite according to claim 1, characterized in that: The second reselection unit includes: A double-drum centrifugal concentrator is provided with a first drum body and a second drum body, wherein the inclined surfaces of the first drum body and the second drum body have an inclination angle of 2° to 8°, the first drum body is used to perform a primary centrifugal impurity removal on the second particle size to obtain a primary impurity-removed tailing and a primary impurity-removed concentrate; the second drum body is used to perform a secondary centrifugal impurity removal on the primary impurity-removed tailing to obtain a second particle size gravity-removed tailing and a secondary impurity-removed concentrate, wherein the primary impurity-removed concentrate and the secondary impurity-removed concentrate are combined into a second particle size gravity-removed concentrate; Wherein, the diameter of the first rotating drum body is smaller than the diameter of the second rotating drum body.

8. The system for gravity separation and impurity removal of low-grade bauxite according to claim 5, characterized in that: The heavy medium used in the first gravity separation unit includes ferrosilicon powder and magnet powder. The ratio of the ferrosilicon powder to the magnet powder is 1:

3. The particle sizes of the ferrosilicon powder and the magnet powder are both less than 0.038 mm.

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