A mineralization and magnetic separation combined iron separation device for red mud separation

Abstract

This invention belongs to the field of magnetic separation technology, and in particular to a device for the coordinated mineralization and magnetic separation of iron in red mud. The lower inner side of the sand mill shell is provided with an arc-shaped concave cavity adapted to a cylindrical grinding rotor. The cylindrical grinding rotor is set in the arc-shaped concave cavity by rotation. Its outer cylindrical surface and the inner wall of the sand mill shell form a non-equidistant grinding chamber with left and right symmetry and a larger upper and smaller lower spacing. The minimum gap between the chambers is located in the bottom area of ​​the arc-shaped concave cavity. An overflow port is opened on the side wall of the sand mill shell in the downstream direction of the slurry flow path. A belt-type iron separator is used to magnetically separate the slurry discharged from the overflow port to remove iron. The slurry after magnetic separation is returned to the inside of the sand mill shell for circulation and re-grinding. The mixture after one grinding is subjected to preliminary magnetic separation to remove iron ore that can be magnetically adsorbed. Then the remaining mixture is circulated again. By diverting the iron-containing particles during the circulation process, it is ground to the target 1μm faster.

Description

Technical Field

[0001] This invention belongs to the field of magnetic separation technology, specifically relating to a device for the coordinated mineralization and magnetic separation of iron in red mud. Background Technology

[0002] Each ton of alumina produces 1 to 1.5 tons of red mud. my country's alumina enterprises produce about 100 million tons of red mud annually. The large-scale stockpiling of red mud causes waste of land resources and environmental pollution. The existing red mud storage facilities use dry stockpiling treatment, and the available storage capacity is estimated to be less than 5 years. There is an urgent need to carry out comprehensive utilization of red mud to reduce the amount of red mud discharged. Red mud has a high iron content and is one of the most valuable metals, but it is not elemental iron, but exists in the form of iron oxide. The iron in red mud is embedded in the mineral in the form of fine grains and inclusions, which cannot be ground finely or separated. It has high alkalinity and severe mudification, making magnetic separation and gravity separation difficult. The iron recovery rate of traditional processes is between 20% and 30%. Because the iron in red mud is not iron blocks or iron powder, but rather iron oxide, aluminosilicates, perovskite and other mineral crystals growing together, it belongs to a symbiotic embedded structure, not a simple mixture. Even after high-temperature melting, it will only become a uniform silicate slurry, where iron, aluminum, silicon, calcium and sodium are all fused together and mixed together in solid solution. After cooling, it is still a mixed solid solution, and the iron is still encapsulated, so it cannot be melted and layered. Currently, the most effective method to improve iron recovery is to first physically decompose the iron and then beneficiate it (the beneficiation method is not limited to stepwise low-temperature pre-modification, segmented gradient magnetization roasting, or in-situ mineralization coupled with magnetization for iron extraction). This requires grinding the red mud to improve its fineness, which is essential for effective subsequent iron beneficiation. Red mud contains hematite (the main iron phase, accounting for 30%–40% of iron, with an average particle size of 10–20 μm), goethite / lepidocrocite (the secondary iron phase, accounting for 20%–30% of iron, with an average particle size of <5 μm), and ferrosilicon / ferroaluminosilicate (bound iron, accounting for 15%–25% of iron, belonging to the submicron scale, with an average particle size of 0.0 μm). Between 5 and 0.5 μm, the iron is integrated into the mineral lattice and is directly discarded as it cannot be used for iron extraction. Magnetite (trace amounts, accounting for less than 5% of iron, with an average particle size between 5 and 30 μm) is also included. Traditional iron extraction processes mainly target magnetite and hematite. If it is necessary to further extract goethite / hydrothermal goethite (ferric silicate / ferric aluminosilicate is lattice-solution ferric silicate, which cannot be dissociated even when ground to below 0.5 μm), then the red mud needs to be ground to the micron level before it can be extracted through subsequent processes. In other words, the iron in this part of the mineral needs to be completely separated from other substances in order to achieve effective iron extraction. Summary of the Invention

[0003] To address the problems mentioned in the background art, this invention provides a red mud separation device that combines mineralization and magnetic separation for iron ore beneficiation. The device first performs preliminary magnetic separation on the mixture after one grinding stage to remove iron ore that can be magnetically adsorbed. Then, the remaining mixture is recycled. During this recycling process, iron-containing particles are diverted out, increasing the proportion of silicon-aluminum inert slag in the mill, improving the shearing efficiency of the grinding media, and enabling faster grinding to the target 1μm size.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a red mud separation and mineralization and magnetic separation synergistic iron separation device, wherein an arc-shaped concave cavity adapted to a cylindrical grinding rotor is provided on the lower inner side of the sand mill shell, the cylindrical grinding rotor is set in the arc-shaped concave cavity by rotation, and a non-equidistant grinding chamber with left and right symmetry and upper and lower non-equidistant spacing is formed between its outer cylindrical surface and the inner wall of the sand mill shell, and the minimum gap between the chambers is located in the bottom area of ​​the arc-shaped concave cavity; An overflow port is provided on the side wall of the mill shell downstream of the slurry flow path. A belt-type iron separator is used to magnetically separate the slurry discharged from the overflow port to remove iron. The slurry after magnetic separation is returned to the inside of the mill shell for further grinding.

[0005] As a preferred embodiment of the red mud separation and mineralization and magnetic separation synergistic iron separation device of the present invention, the mill shell is connected to a feed pipe in the direction away from the overflow port.

[0006] As a preferred embodiment of the red mud separation and mineralization and magnetic separation synergistic iron separation device of the present invention, a bottom plate parallel to the belt-type iron separator is fixedly connected to one side of the sand mill shell, and the bottom end face of the overflow port is flush with the upper surface of the bottom plate, and the gap between the belt-type iron separator and the bottom plate is smaller than the internal gap of the overflow port. Along the rotation direction of the belt-type iron separator, the length of the bottom plate is shorter than that of the belt-type iron separator, and the end of the bottom plate is fixedly connected to the return hopper, and the bottom of the return hopper is connected to the return pipe.

[0007] As a preferred embodiment of the red mud separation and mineralization and magnetic separation synergistic iron separation device of the present invention, the belt-type iron separator has a scraper at the end away from the overflow port, and a discharge funnel is provided below the scraper.

[0008] As a preferred embodiment of the red mud separation and mineralization and magnetic separation synergistic iron separation device of the present invention, it further includes an air inlet pipe arranged along the return direction of the return pipe, one end of which extends to the inside of the return pipe.

[0009] As a preferred embodiment of the red mud separation and mineralization and magnetic separation synergistic iron separation device of the present invention, the return pipe includes a filter section for screening out qualified powder.

[0010] As a preferred embodiment of the red mud separation and mineralization and magnetic separation synergistic iron separation device of the present invention, the filter section is made of a semi-rigid material and the horizontal section has a curved structure.

[0011] As a preferred embodiment of the red mud separation and mineralization and magnetic separation synergistic iron separation device of the present invention, the outer side of the filter section is covered with a collection shell, the two ends of the collection shell are fixedly connected to the rigid parts of the return pipe, and the lower part of the collection shell is connected to the collection pipe.

[0012] As a preferred embodiment of the red mud separation and mineralization and magnetic separation synergistic iron separation device of the present invention, a baffle is provided at the top center of the sand mill shell.

[0013] As a preferred embodiment of the red mud separation and mineralization and magnetic separation co-selection iron device of the present invention, the sand mill shell includes a main body and a cover plate fixedly connected to the top of the main body. A baffle is fixed at the bottom surface of the cover plate, and the length of the baffle is the same as the length of the cover plate. Side plates are fixedly connected to both sides of the main body, and the side plates are provided with notches that cooperate with the baffle.

[0014] Compared with the prior art, the beneficial effects of this invention are as follows: This solution involves adding zirconia ceramic microspheres (with a diameter between 0.5 and 2 mm) to the mill housing and mixing them with red mud for grinding. The mixture (comprising red mud and zirconia ceramic microspheres) is added to the left side of the mill housing. Through the counter-clockwise rotation of the cylindrical grinding rotor, the mixture is moved from a grinding chamber with a larger gap to a grinding chamber with a smaller gap by the rolling and pressing action of the cylindrical grinding rotor. During this process, the zirconia ceramic microspheres shear, impact, and compress, tearing and peeling the red mud particles layer by layer, thus grinding the red mud to the micron level and separating goethite / water goethite from other substances. Of course, a single grinding operation cannot reach the micron level. To achieve the desired level, multiple grinding cycles are required. To improve efficiency and reduce equipment load, the mixture after one grinding stage undergoes preliminary magnetic separation to remove iron ore that can be magnetically adsorbed. The remaining mixture is then recycled. By diverting iron-containing particles during the recycling process, the proportion of silicon-aluminum inert slag in the mill increases, resulting in better shearing efficiency of the grinding media and faster grinding to the target 1μm. If the iron-containing particles are not diverted and grinding continues until 1μm, some iron will be ground into submicron ultrafine mud, which is difficult to capture with magnetic separation and will be lost with the tailings. Mid-process pre-magnetic separation can prevent large iron particles from being crushed, improve the overall recovery rate, and ultimately achieve time-saving, energy-saving, and reduced ultrafine mud formation. Attached Figure Description

[0015] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the internal structure of the present invention; Figure 3 This is a cross-sectional view of the overall structure in this invention; In the picture: 1. Grinding mill housing; 2. Cylindrical grinding rotor; 3. Overflow port; 4. Belt-type iron separator; 5. Feed pipe; 6. Base plate; 7. Return hopper; 8. Return pipe; 9. Scraper; 10. Discharge hopper; 11. Air inlet pipe; 12. Filter section; 13. Collection housing; 14. Collection pipe; 15. Baffle; 16. Cover plate; 17. Side plate; 18. Main body; 19. Drive shaft. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] like Figures 1-3 As shown: A red mud separation and mineralization and magnetic separation combined iron separation device, wherein the lower inner side of the sand mill shell 1 is provided with an arc-shaped concave cavity adapted to the cylindrical grinding rotor 2, the cylindrical grinding rotor 2 is set in the arc-shaped concave cavity by rotation, and the outer cylindrical surface of the rotor 2 and the inner wall of the sand mill shell 1 form a non-equidistant grinding chamber with left and right symmetry and upper and lower size, and the minimum gap between the chambers is located in the bottom area of ​​the arc-shaped concave cavity; An overflow port 3 is provided on the side wall of the mill shell 1 in the downstream direction of the slurry flow path. The belt-type iron remover 4 is used to magnetically separate the slurry discharged from the overflow port 3 to remove iron. The slurry after magnetic separation is returned to the inside of the mill shell 1 for circulation and re-grinding.

[0018] Each ton of alumina produces 1 to 1.5 tons of red mud. my country's alumina enterprises produce about 100 million tons of red mud annually. The large-scale stockpiling of red mud causes waste of land resources and environmental pollution. The existing red mud storage facilities use dry stockpiling treatment, and the available storage capacity is estimated to be less than 5 years. There is an urgent need to carry out comprehensive utilization of red mud to reduce the amount of red mud discharged. Red mud has a high iron content and is one of the most valuable metals, but it is not elemental iron, but exists in the form of iron oxide. The iron in red mud is embedded in the mineral in the form of fine grains and inclusions, which cannot be ground finely or separated. It has high alkalinity and severe mudification, making magnetic separation and gravity separation difficult. The iron recovery rate of traditional processes is between 20% and 30%. Because the iron in red mud is not iron blocks or iron powder, but rather iron oxide, aluminosilicates, perovskite and other mineral crystals growing together, it belongs to a symbiotic embedded structure, not a simple mixture. Even after high-temperature melting, it will only become a uniform silicate slurry, where iron, aluminum, silicon, calcium and sodium are all fused together and mixed together in solid solution. After cooling, it is still a mixed solid solution, and the iron is still encapsulated, so it cannot be melted and layered. Currently, the most effective method to improve iron recovery is to first physically decompose the iron and then beneficiate it (the beneficiation method is not limited to stepwise low-temperature pre-modification, segmented gradient magnetization roasting, or in-situ mineralization coupled with magnetization for iron extraction). This requires grinding the red mud to improve its fineness, which is essential for effective subsequent iron beneficiation. Red mud contains hematite (the main iron phase, accounting for 30%–40% of iron, with an average particle size of 10–20 μm), goethite / lepidocrocite (the secondary iron phase, accounting for 20%–30% of iron, with an average particle size of <5 μm), and ferrosilicon / ferroaluminosilicate (bound iron, accounting for 15%–25% of iron, belonging to the submicron scale, with an average particle size of 0.0 μm). Between 5 and 0.5 μm, the iron is integrated into the mineral lattice and is discarded directly as it cannot be used for iron extraction. Magnetite (trace amounts, accounting for less than 5% of iron, with an average particle size between 5 and 30 μm) is also included. Traditional iron extraction processes mainly target magnetite and hematite. If it is necessary to further extract goethite / hydrothermal goethite (ferric silicate / ferric aluminosilicate is lattice-solution ferric silicate, which cannot be dissociated even when ground to below 0.5 μm), then the red mud needs to be ground to the micron level before it can be extracted through subsequent processes. In other words, the iron in this part of the mineral needs to be completely separated from other substances in order to achieve effective iron extraction in the subsequent process. This method involves adding zirconia ceramic microspheres (with a diameter between 0.5 and 2 mm) to the mill housing 1 and mixing them with red mud for grinding. Figure 3 As shown, a mixture (comprising red mud and zirconia ceramic microspheres) is added to the left side of the mill housing 1. The mixture is then fed into a cylindrical grinding rotor 2 rotating counter-clockwise. The drive unit directly drives the cylindrical grinding rotor 2 via drive shaft 19, moving the mixture from the larger-gap grinding chamber to the smaller-gap grinding chamber via the rolling and pressing action of the cylindrical grinding rotor 2. During this process, the zirconia ceramic microspheres shear, impact, and compress, tearing and peeling the red mud particles layer by layer, thus grinding the red mud to the micron level. This separates goethite / water goethite from other substances. Of course, a single grinding cycle cannot achieve the micron level; multiple cycles of grinding are required. To improve work efficiency and reduce equipment load, the mixture after one grinding stage undergoes preliminary magnetic separation to remove iron ore that can be magnetically adsorbed. The remaining mixture is then recycled. By diverting iron-containing particles during the recycling process, the proportion of silicon-aluminum inert slag in the mill increases, resulting in better shearing efficiency of the grinding media and faster grinding to the target 1μm. If the iron-containing particles are not diverted and grinding continues until 1μm, some iron will be ground into submicron ultrafine mud, which is difficult to capture by magnetic separation and will be lost with the tailings. Mid-process pre-magnetic separation can prevent large iron particles from being ground up, improve the overall recovery rate, and ultimately achieve time-saving, energy-saving, and reduced ultrafine mud formation.

[0019] In an optional embodiment, the mill housing 1 is connected to a feed pipe 5 in a direction away from the overflow port 3.

[0020] In this embodiment, when the grinding work in the equipment reaches the particle size balance (the particle size will no longer become finer even if the grinding time is extended) or when there is a shortage of material in the equipment, new red mud can be transported through the feed pipe 5. The red mud fed in must first be ground to below 200 mesh, otherwise it will affect the working efficiency or even damage the equipment.

[0021] In an optional embodiment, a base plate 6 parallel to the belt-type iron separator 4 is fixedly connected to one side of the sand mill housing 1, and the bottom end face of the overflow port 3 is flush with the upper surface of the base plate 6. The gap between the belt-type iron separator 4 and the base plate 6 is smaller than the internal gap of the overflow port 3. Along the rotation direction of the belt-type iron separator 4, the length of the bottom plate 6 is shorter than that of the belt-type iron separator 4, and the end of the bottom plate 6 is fixedly connected to the return hopper 7. The bottom end of the return hopper 7 is connected to the return pipe 8.

[0022] In this embodiment, the belt-type iron separator 4 can be fixed by the fixing plates on both sides of the base plate 6 (e.g., Figure 1 As shown), when the mixture inside the mill housing 1 is discharged from the overflow port 3, it will be driven by the belt rotation of the belt-type iron separator 4 to move towards the return hopper 7. When the mixture moves to the top of the return hopper 7, the mixture that is not magnetically attracted by the belt-type iron separator 4 will fall directly from the return hopper 7 into the return pipe 8, while the metal minerals that are magnetically attracted by the belt-type iron separator 4 will continue to move along the belt until they are scraped off by the scraper 9.

[0023] In an optional embodiment, the end of the belt separator 4 away from the overflow port 3 is in contact with a scraper 9, and a discharge hopper 10 is provided below the scraper 9.

[0024] In this embodiment, the metal mineral scraped off by the scraper 9 will fall down along the feeding funnel 10.

[0025] In an optional embodiment, an air inlet pipe 11 is further included, which is arranged along the return direction of the return pipe 8, with one end of the air inlet pipe 11 extending to the inside of the return pipe 8.

[0026] In this embodiment, the mixture flowing back to the mill housing 1 along the return pipe 8 is mainly achieved by wind blowing.

[0027] In an optional embodiment, the return pipe 8 includes a filter section 12 for sieving out qualified powder.

[0028] In this embodiment, the particle size of the qualified powder can be 1.2μm, 1μm, or 0.8μm. The filter section 12 is a tubular filter screen with the target particle size. When the mixture flowing with the air passes through the filter section 12, the powder with the qualified particle size will pass through the filter section 12.

[0029] In an optional embodiment, the filter section 12 is made of a semi-rigid material and the horizontal section has a curved structure, and the airflow introduced through the air inlet duct 11 is a pulsed airflow.

[0030] In this embodiment, since the horizontal section is more prone to clogging the filter holes, when the horizontal section is designed as a curved structure under the premise that the filter section 12 is semi-rigid, the airflow will cause the filter section 12 to vibrate, which will help the particles that are clogged in the filter section 12 to be shaken off. The vibration mainly occurs in the horizontal section of the filter section 12, and will also affect the vertical section to vibrate. Of course, when the airflow introduced through the air inlet pipe 11 is a pulsed airflow, the effect is better and it is easier to cause the curved structure to vibrate.

[0031] In an optional embodiment, the outer side of the filter section 12 is covered by a collection housing 13, the two ends of the collection housing 13 are fixedly connected to the rigid part of the return pipe 8, and the lower part of the collection housing 13 is connected to the collection pipe 14.

[0032] In this embodiment, particles falling from the filter section 12 are collected by the collection housing 13 and finally extracted by the collection tube 14. The end of the collection tube 14 can be connected to a negative pressure collector.

[0033] In an optional embodiment, a baffle 15 is provided at the top center of the sanding housing 1.

[0034] In this embodiment, the mixture flowing back from the end of the return pipe 8 to the inside of the mill housing 1 is pneumatically conveyed. To prevent the mixture flowing back to the inside of the mill housing 1 from directly entering the right side of the mill housing 1 under the action of the wind (e.g., ... Figure 3 As shown in the figure, baffle 15 is needed to block the flow and prevent too much mixture from entering the right side of the mill housing 1.

[0035] In an optional embodiment, the sanding housing 1 includes a main body 18 and a cover plate 16 fixedly connected to the top of the main body 18. A baffle 15 is fixed to the bottom surface of the cover plate 16. The length of the baffle 15 is the same as the length of the cover plate 16. Side plates 17 are fixedly connected to both sides of the main body 18. The side plates 17 are provided with notches that cooperate with the baffle 15. The cover plate 16, the side plates 17 and the main body 18 can be fixed together by bolts.

[0036] In this embodiment, when the inside of the sanding housing 1 needs to be cleaned, directly removing the side wall is the most advantageous cleaning method. In order to ensure the overall structural strength of the sanding housing 1 after the side plate 17 is installed, the embedded structural strength is increased by embedding the end of the baffle 15 into the side plate 17, so as to avoid the sanding housing 1 from twisting.

[0037] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A device for the coordinated mineralization and magnetic separation of iron from red mud, characterized in that: The lower inner side of the sand mill housing (1) is provided with an arc-shaped cavity adapted to the cylindrical grinding rotor (2). The cylindrical grinding rotor (2) is set in the arc-shaped cavity by rotation. Its outer cylindrical surface and the inner wall of the sand mill housing (1) form a non-equal-spaced grinding chamber that is symmetrical from left to right and larger at the top and smaller at the bottom. The minimum gap between the chambers is located in the bottom area of ​​the arc-shaped cavity. The side wall of the mill shell (1) in the downstream direction of the slurry flow path is provided with an overflow port (3). The belt-type iron remover (4) is used to magnetically separate the slurry discharged from the overflow port (3) to remove iron. The slurry after magnetic separation is returned to the inside of the mill shell (1) for re-grinding.

2. The red mud separation and mineralization and magnetic separation synergistic iron separation device according to claim 1, characterized in that: The mill housing (1) is connected to the feed pipe (5) in the direction away from the overflow port (3).

3. The red mud separation and mineralization and magnetic separation synergistic iron separation device according to claim 1, characterized in that: A base plate (6) parallel to the belt separator (4) is fixedly connected to one side of the sand mill housing (1), and the bottom end face of the overflow port (3) is flush with the upper surface of the base plate (6). The gap between the belt separator (4) and the base plate (6) is smaller than the internal gap of the overflow port (3). Along the rotation direction of the belt-type iron separator (4), the length of the bottom plate (6) is shorter than that of the belt-type iron separator (4), and the end of the bottom plate (6) is fixedly connected to the return funnel (7), and the bottom end of the return funnel (7) is connected to the return pipe (8).

4. The red mud separation and mineralization and magnetic separation synergistic iron separation device according to claim 1, characterized in that: The belt-type iron separator (4) has a scraper (9) at the end away from the overflow port (3), and a discharge funnel (10) is provided below the scraper (9).

5. The red mud separation and mineralization and magnetic separation synergistic iron separation device according to claim 3, characterized in that: It also includes an air inlet pipe (11) arranged along the return direction of the return pipe (8), with one end of the air inlet pipe (11) extending to the inside of the return pipe (8).

6. The red mud separation and mineralization and magnetic separation synergistic iron separation device according to claim 5, characterized in that: The return pipe (8) includes a filter section (12) for screening out qualified powder.

7. The red mud separation and mineralization and magnetic separation synergistic iron separation device according to claim 6, characterized in that: The filter section (12) is made of a semi-rigid material and the horizontal section is a curved structure.

8. The red mud separation and mineralization and magnetic separation synergistic iron separation device according to claim 6 or 7, characterized in that: The outer side of the filter section (12) is covered by a collection shell (13). The two ends of the collection shell (13) are fixedly connected to the rigid part of the return pipe (8). The lower part of the collection shell (13) is connected to the collection pipe (14).

9. The red mud separation and mineralization and magnetic separation synergistic iron separation device according to claim 1, characterized in that: A baffle (15) is provided at the top center of the sanding housing (1).

10. The red mud separation and mineralization and magnetic separation synergistic iron separation device according to claim 9, characterized in that: The sanding housing (1) includes a main body (18) and a cover plate (16) fixedly connected to the top of the main body (18). A baffle (15) is fixed on the bottom surface of the cover plate (16). The length of the baffle (15) is the same as the length of the cover plate (16). Side plates (17) are fixedly connected to both sides of the main body (18). The side plates (17) are provided with notches that cooperate with the baffle (15).

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