Method for extracting iron from fine-fraction red mud iron separation tailings

Abstract

The invention relates to the technical field of comprehensive utilization of colored industrial solid wastes, in particular to a method for extracting iron from fine-fraction red mud iron separation tailings. The iron content of the iron separation tailings is larger than or equal to 18%, and the method comprises the steps that magnetic seeds and the iron separation tailings are mixed for the first time according to a first preset mass ratio, and roughing raw materials are obtained; performing first magnetic separation on the roughing raw material to obtain first iron ore concentrate and roughing tailings; the magnetic seeds and the roughing tailings are secondarily mixed according to a second preset mass ratio, and scavenging raw materials are obtained; performing second magnetic separation on the scavenging raw material to obtain second iron ore concentrate and treated tailings; and magnetic seeds of the first iron ore concentrate and the second iron ore concentrate are recycled, and magnetic seeds and iron ore concentrate are obtained. According to the method, the total recovery rate of iron in the red mud tailings is increased to be greater than or equal to 45.82% and the iron content of the iron ore concentrate is greater than or equal to 46.33% through strategies such as accurate quantitative feeding of the magnetic seeds, micro-interface regulation and control of an ore pulp system, grading reinforcement of magnetic agglomeration and closed-loop regeneration of the magnetic seeds.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of comprehensive utilization of non-ferrous industrial solid waste, and particularly relates to a method for extracting iron from fine-particle-level red mud iron tailings. BACKGROUND

[0002] Red mud is a solid waste generated in the production process of alumina. Due to its strong alkalinity, fine particle size and complex properties, red mud is difficult to utilize, and is generally treated by stacking process at present. However, red mud contains a large amount of valuable metals such as iron, titanium, lithium, gallium, calcium and rare earth elements. The stacking of red mud not only pollutes the environment, but also leads to the secondary loss and waste of resources. If the iron-containing minerals are recovered from red mud, not only can the ordered reduction and resource utilization of red mud solid waste be realized, but also the healthy and high-quality development of the alumina industry can be ensured. In addition, iron concentrate can be used as a raw material for steel smelting, which can ensure the safe supply of iron resources.

[0003] At present, the main processes for extracting iron from red mud are mainly magnetic separation and gravity separation, and the yield of the obtained iron concentrate is generally 20% to 50%. At present, the methods for extracting iron concentrate from red mud include: (1) red mud iron extraction process, which connects the iron extraction process after the last washing of red mud, cuts off the red mud discharged from the last washing sedimentation tank, and implements a roughing, a cleaning and a scavenging process, thereby improving the recovery efficiency of metallic iron in red mud. (2) Method for gradient resource utilization of low-temperature Bayer red mud, which involves preliminarily grinding the low-temperature Bayer red mud to obtain a first grinding material, then using strong magnetic technology to concentrate the grinding material to separate magnetic iron concentrate I and iron tailings I. Then the iron tailings I is reduced and roasted to obtain a reduction roasting product; the reduction roasting product is ground to obtain a second grinding material; then the second grinding material is concentrated by weak magnetism to obtain magnetic iron concentrate II and iron tailings II; the magnetic iron concentrate I and the magnetic iron concentrate II are subjected to acid leaching to recover iron; the iron tailings II is subjected to acid leaching to obtain a titanium-aluminum leaching solution; the titanium-aluminum leaching solution is separated into aluminum and titanium by a precipitation-flotation process. (3) Red mud suspension magnetization roasting-grinding and concentration process for producing iron concentrate, which dries the iron-containing red mud to obtain dried red mud; then the dried red mud is mixed with additives to obtain a mixed mixture; the mixed mixture is finely crushed and mixed to obtain a mixture; then the mixture is placed in a suspension heating furnace, and the reduction time is accurately controlled to 15 to 25 seconds, and the reduction end point temperature is controlled to 800 to 900 DEG C, to implement suspension magnetization reduction roasting, and finally produce high-temperature roasting material. The high-temperature roasting material is cooled by an oxygen-free cooling device and wet grinding to obtain a grinding material; the grinding material is subjected to magnetic separation treatment by two magnetic separators, and iron concentrate with high grade can be obtained.

[0004] However, the current method of extracting iron concentrate from red mud faces a common problem: even after extraction, a large amount of iron minerals remains in the remaining iron separation tailings, and direct disposal will result in significant waste of iron resources. SUMMARY

[0005] The present application provides a method for extracting iron from fine particle grade red mud iron separation tailings to solve the technical problem of how to improve the recovery rate of iron in red mud iron separation tailings. In a first aspect, the embodiments of the present application provide a method for extracting iron from fine particle grade red mud iron separation tailings, the iron content of the red mud iron separation tailings being ≥18%, the method comprising: mixing the magnetic seeds and the iron separation tailings at a first preset mass ratio to obtain a rough separation raw material; performing first magnetic separation on the rough separation raw material to obtain a first iron concentrate and a rough separation tailings; mixing the magnetic seeds and the rough separation tailings at a second preset mass ratio to obtain a scavenging raw material; performing second magnetic separation on the scavenging raw material to obtain a second iron concentrate and a treatment tailings; combining the first iron concentrate and the second iron concentrate to obtain a mixed iron concentrate; recovering the magnetic seeds from the mixed iron concentrate according to a preset recovery process to obtain magnetic seeds and an iron concentrate.

[0006] Optionally, the particle size of the magnetic seeds is 0.08mm to 1.00mm.

[0007] Optionally, the magnetic seeds include fine particle grade magnetic seeds, the mass of the fine particle grade magnetic seeds being 20% to 50% of the total mass of the magnetic seeds; and the particle size of the fine particle grade magnetic seeds is ≤0.1mm.

[0008] Optionally, the magnetic seeds are natural iron minerals and / or artificially synthesized iron minerals.

[0009] Optionally, when the magnetic seeds are natural iron minerals, the natural iron minerals include at least one of the following: magnetite, hematite, siderite, and ilmenite; and / or when the magnetic seeds are artificially synthesized iron minerals, the artificially synthesized iron minerals include silicon iron powder and / or magnetic ferrite.

[0010] Optionally, the first preset mass ratio is (5 to 15):100; and / or the second preset mass ratio is (15 to 25):100.

[0011] Optionally, the magnetic field strength of the first magnetic separation is 0.6T to 1.2T; and / or The magnetic field strength of the second magnetic separation is 1.3T to 1.6T.

[0012] Optionally, the first magnetic separation and the second magnetic separation are both carried out by using a steel rod magnetic gathering medium as a separation carrier, the diameter of the steel rod magnetic gathering medium used in the first magnetic separation is 2mm to 3mm, and the diameter of the steel rod magnetic gathering medium used in the second magnetic separation is 1.5mm to 2.0mm.

[0013] Optionally, the preset recovery process includes at least one of the following: table gravity separation, screening and magnetic separation process.

[0014] Optionally, the mass concentration of the roughing raw material is 18% to 25%; and / or The iron content of the iron tailings is 18% to 38%; and the particle size of the iron tailings is ≤0.074mm.

[0015] Compared with the prior art, the above technical solution provided by the embodiments of the present application has the following advantages: The method for recovering iron from fine particle grade red mud iron tailings provided by the embodiments of the present application uses red mud iron tailings as raw material, first mixes the red mud iron tailings with magnetic seeds in a specific preset mass ratio, which can promote the uniform dispersion between the magnetic seeds and the red mud iron tailings, and form uniformly dispersed roughing raw material, then carries out first magnetic separation on the roughing raw material, in this process, the magnetic seeds form magnetic chains or magnetic agglomerates, and these magnetic agglomerates can physically capture or magnetically adsorb weakly magnetic fine particle iron minerals in the red mud iron tailings and intergrowths that have not been monomer dissociated, and preliminarily rough out the iron minerals with relatively strong magnetism in the iron tailings, so as to improve the recovery rate of the iron minerals in the red mud iron tailings; in addition, the roughing tailings obtained by the first magnetic separation and the magnetic seeds are mixed again in a specific preset mass ratio and subjected to second magnetic separation, which can further physically capture or magnetically adsorb the iron minerals with weaker magnetism in the fine particle grade red mud iron tailings through the magnetic seeds, and further sweep out the iron minerals with weaker magnetism in the roughing tailings, so as to further improve the recovery rate of the iron minerals in the red mud iron tailings; in addition, the first iron concentrate obtained by the first magnetic separation and the second iron concentrate obtained by the second magnetic separation are combined and then subjected to magnetic seed recovery according to a preset recovery process, so that the magnetic seeds are fully dissociated and efficiently recovered, the activity and quantity of the magnetic seeds in the whole method are maintained, and at the same time, the magnetic seeds are prevented from interfering with the recovery of the iron minerals in the iron tailings and from being lost in the tailings. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings, which are incorporated herein and constitute part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

[0018] Figure 1 A process flow diagram of a method for extracting iron from fine particle level red mud iron tailings provided by the embodiments of the present application; Figure 2 A practical process flow diagram of a method for extracting iron from fine particle level red mud iron tailings provided by the embodiments of the present application. DETAILED DESCRIPTION

[0019] In order to more clearly illustrate the purposes, technical solutions and advantages of the embodiments of the present application, the technical solutions in the embodiments will be comprehensively and specifically described below with reference to the drawings. Obviously, the described embodiments are only examples and not the whole implementation scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without any creative effort fall within the scope of the present application.

[0020] The range descriptions described in the present application, such as numerical range, ratio range, etc., all include all possible sub-ranges and single values within the range, for example, the range description of "1 to 6" or "1~6" covers all sub-ranges (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6) between 1 and 6. Unless otherwise specified, the terms "comprise" and the like used in the present application mean "include but not limited to"; the relationship terms "first", "second", etc. are only used to distinguish different entities or operations, and do not imply actual sequence or relationship; "and / or" means that multiple cases can exist independently or simultaneously; "at least one", "multiple", "at least one" and the like refer to any combination of the corresponding objects, including single or multiple combinations of objects. The proportional relationship involved in the present application, such as mass ratio, molar ratio, etc., should be understood as the corresponding relationship between the front and rear terms in the proportional form according to the sequence of description. The raw materials, reagents, instruments and equipment used in the present application can be purchased or prepared by existing methods.

[0021] It should be noted that for the prior art (1) mentioned in the background art, the inventors point out that this method has the problems of low iron concentrate yield, insufficient comprehensive utilization rate, and poor quality of iron concentrate. As for the prior art (2) described in the background art, the inventors find that it has the problems of low utilization rate of red mud, low yield of iron concentrate, high cost of drying red mud, serious loss of fine particle size of red mud, and high impurity content of iron concentrate. As for the prior art (3) recorded in the background art, the inventors reveal that this method faces the challenges of high cost of drying red mud, easy scarring in the process of suspended magnetization roasting, large loss of fine particle size of red mud, and high impurity content of iron concentrate.

[0022] Figure 1 An exemplary flowchart of a method for extracting iron from fine particle size red mud iron tailings is shown; As Figure 1 shown, the present application provides a method for extracting iron from fine particle size red mud iron tailings, the iron content of the red mud iron tailings is ≥18%, the method comprises: S1. Mix the magnetic seeds and the iron tailings at a first predetermined mass ratio to obtain a roughing raw material; S2. Perform first magnetic separation on the roughing raw material to obtain a first iron concentrate and a roughing tailings; S3. Mix the magnetic seeds and the roughing tailings at a second predetermined mass ratio to obtain a scavenging raw material; S4. Perform second magnetic separation on the scavenging raw material to obtain a second iron concentrate and a treatment tailings; S5. Recycle the magnetic seeds from the first iron concentrate and the second iron concentrate to obtain magnetic seeds and iron concentrate.

[0023] It should be noted that the first mixing can be performed by slurry mixing and stirring.

[0024] It should be noted that the recycling of the magnetic seeds can be selectively performed by processes such as gravity separation, screening, and magnetic separation according to the composition of the first iron concentrate and the second iron concentrate.

[0025] It should be noted that the magnetic seeds obtained by magnetic seed recycling can be reused as the magnetic seeds for first magnetic separation and second magnetic separation.

[0026] It should be noted that the method for extracting iron from fine particle size red mud iron tailings provided by the present application is based on the magnetic seed induced classification magnetic agglomeration technology, and a closed loop separation system of "pre-dispersion-roughing-scavenging-magnetic seed circulation" is constructed to significantly improve the recovery rate of iron minerals in red mud iron tailings. The specific mechanism is as follows: 1. Pre-dispersion mixing (first mixing): With the first pre-set mass ratio controlled accurately, the high-activity magnetic seeds are forced to mix with the red mud iron tailings.

[0027] Effect: Ensure the uniform dispersion of magnetic seeds at the microscale between red mud iron tailings particles, eliminate the agglomeration dead angle of red mud iron tailings; establish sufficient physical contact basis for subsequent magnetic agglomeration, avoid local overload or insufficient contact.

[0028] 2. Activation of slurry: The mixed raw materials are subjected to slurry conditioning treatment to optimize the concentration and flow state, forming a coarse ore slurry with suitable fluidity.

[0029] Effect: Create a turbulent environment to enhance the collision kinetic energy between particles; Adjust the chemical environment of the ore slurry (e.g. pH, ionic strength), adjust the electrical properties of the surface of fine and ultra-fine iron minerals in red mud iron tailings, and optimize the adsorption conditions of magnetic seeds.

[0030] 3. Coarse separation magnetic separation (first magnetic separation): The coarse ore slurry is subjected to the first magnetic separation under optimized magnetic field strength.

[0031] Mechanism: Magnetic seeds are arranged in a directional manner to form magnetic chains / magnetic agglomerates in the magnetic field of the first magnetic separation; Through the dual-effect synergistic mechanism of "magnetic attraction capture" (direct magnetization adsorption of weakly magnetic iron minerals in red mud iron tailings) and "physical net capture" (mechanical wrapping of fine and ultra-fine iron minerals and intergrowths in red mud iron tailings), the apparent magnetism of target minerals is significantly improved; Realize efficient co-recovery of strongly magnetic components (primary magnetite) and easily agglomerated weakly magnetic components (hematite, goethite), and produce the first iron concentrate.

[0032] 3. Scavenging enhancement (second mixing + second magnetic separation): Add magnetic seeds to the coarse tailings at a specific second pre-set mass ratio, and form a scavenging raw material after secondary mixing.

[0033] Effect: The iron minerals in the coarse tailings are low in grade, weak in magnetism, or complex in embedding, and need to be "reactivated" by supplementing magnetic seeds; Rebuild the magnetic seed-mineral contact interface through secondary mixing, and directionally strengthen the agglomeration of difficult-to-recover residual iron minerals.

[0034] The scavenging magnetic separation uses an enhanced magnetic field to deeply capture ultra-fine particle size and extremely weak magnetic iron minerals missed in the coarse separation, producing a second iron concentrate, thereby maximizing the recovery of iron minerals in red mud iron tailings.

[0035] 4. Closed-loop recovery of magnetic seeds and resource integration: The first iron concentrate and the second iron concentrate are integrated, and efficient dissociation and recovery treatment (such as low-intensity magnetic separation, screening, gravity separation, etc.) of magnetic seeds is performed.

[0036] Effects: 1) Recycling: The recycled high-activity magnetic seeds are returned to the system for reuse, significantly reducing operating costs; 2) Grade improvement: Removing non-magnetic inclusions simultaneously improves the final iron concentrate grade; 3) System stability: Maintaining the stability of the number and activity of magnetic seeds.

[0037] 5. Comprehensive strategy: (1) Hierarchical agglomeration strategy: Through the two-stage magnetic seed induction mechanism of "main recovery roughing + deep capture scavenging", combined with two-stage magnetic separation (roughing + scavenging), the hierarchical recovery of iron minerals with wide magnetic distribution in fine particle size red mud iron tailings can be achieved, breaking through the bottleneck of low recovery rate of single magnetic separation.

[0038] (2) Magnetic-mechanical cooperative capture: Magnetic agglomerates simultaneously exert magnetic attraction and physical entrapment effects, solving the problem of fine particles (<10 μm) and intergrowths of iron minerals in recycled red mud iron tailings.

[0039] (3) Internal recycling economy: The magnetic seed efficient recovery system forms a resource closed loop, reducing the dependence on external magnetic seeds and improving the sustainability of the process.

[0040] In summary, the method for extracting iron from fine particle size red mud iron tailings provided by the embodiments of the present application significantly improves the total recovery rate of iron in red mud iron tailings through precise quantitative addition of magnetic seeds, micro-interface regulation of the slurry system, hierarchical strengthening of magnetic agglomeration, and closed-loop regeneration of magnetic seeds, while ensuring the grade of the iron concentrate, providing an efficient technical path for the resourceization of red mud solid waste.

[0041] In some optional embodiments, the particle size of the magnetic seeds is 0.08 mm to 1.00 mm.

[0042] In these embodiments, magnetic seeds with a particle size of 0.08 mm to 1.00 mm can be directionally arranged to form magnetic chains / magnetic agglomerates in a magnetic field. These magnetic chains / magnetic agglomerates rely on the'magnetic attraction capture' mechanism (i.e., direct magnetization adsorption of weakly magnetic iron minerals) and the 'physical net capture' mechanism (i.e., mechanical wrapping of fine particle iron ore and intergrowths), achieving a dual-effect synergy, thereby improving the output rate of iron concentrate in two-stage magnetic separation. In addition, based on this dual-effect synergy mechanism, the mechanical inclusion phenomenon of non-magnetic minerals can be reduced during the two-stage magnetic separation process to improve the separation accuracy, thereby improving the efficient recovery of iron concentrate and increasing the iron content in the iron tailings.

[0043] The particle size of the magnetic seeds includes, but is not limited to, 0.08 mm, 0.10 mm, 0.12 mm, 0.14 mm, 0.16 mm, 0.18 mm, 0.20 mm, 0.30 mm, 0.40 mm, 0.50 mm, 0.60 mm, 0.70 mm, 0.80 mm, 0.90 mm, or 1.00 mm.

[0044] In some alternative embodiments, the magnetic seeds include fine particle size magnetic seeds, the mass of the fine particle size magnetic seeds being 20% to 50% of the total mass of the magnetic seeds; the particle size of the fine particle size magnetic seeds being ≤0.1 mm.

[0045] The use of fine particle size magnetic seeds with a mass of 20% to 50% of the total mass can more effectively promote the directional arrangement of the seeds to form magnetic chains or magnetic agglomerates, thereby improving the yield of the two-stage magnetic separation of iron concentrate. At the same time, the fine particle size magnetic seeds can reduce the difficulty of recovery in the subsequent magnetic seed recovery stage, thereby effectively improving the recovery rate of the final iron concentrate.

[0046] The mass of the fine particle size magnetic seeds includes, but is not limited to, 20%, 25%, 30%, 35%, 40%, 45%, or 50% of the total mass of the magnetic seeds.

[0047] In some alternative embodiments, the magnetic seeds are natural iron minerals and / or artificially synthesized iron minerals.

[0048] In these embodiments, the use of natural iron minerals and / or artificially synthesized iron minerals as magnetic seeds can cover a wide range of strong magnetic iron seeds, and these seeds can be more effectively arranged into magnetic chains or magnetic agglomerates, thereby improving the accuracy and efficiency of the magnetic separation process to achieve a large amount of recovery of iron concentrate from red mud tailings and an improvement in the indicators of the iron concentrate.

[0049] In some alternative embodiments, in the case where the magnetic seeds are natural iron minerals, the natural iron minerals include at least one of the following: magnetite, hematite, siderite, and ilmenite; and / or In the case where the magnetic seeds are artificially synthesized iron minerals, the artificially synthesized iron minerals include silicon iron powder and / or magnetic ferrite.

[0050] In these embodiments, the use of natural iron minerals including at least one of magnetite, hematite, siderite, or ilmenite as strong magnetic seeds can more effectively be arranged into magnetic chains or magnetic agglomerates, thereby improving the yield of iron concentrate in the two-stage magnetic separation. In addition, the use of iron powder and / or magnetic ferrite as artificially synthesized iron minerals can serve as strong magnetic seeds, and these magnetic seeds can be better arranged into magnetic chains / magnetic agglomerates to improve the yield of iron concentrate in the two-stage magnetic separation.

[0051] In some optional embodiments, the first preset mass ratio is (5 to 15): 100; and / or The second preset mass ratio is (15 to 25): 100.

[0052] In these embodiments, the first preset mass ratio of (5 to 15): 10 can facilitate sufficient magnetic seeds in the red mud iron tailings, which can better orient and arrange to form magnetic chains / magnetic agglomerates in the process of the first magnetic separation, so as to improve the yield of the iron concentrate obtained by the first magnetic separation; in addition, these magnetic seeds can also reduce the mechanical inclusions of non-magnetic minerals in the process of the first magnetic separation, thereby improving the accuracy of the separation. In addition, the second preset mass ratio of (15 to 25): 100 can facilitate sufficient magnetic seeds in the roughing tailings, which can better orient and arrange to form magnetic chains / magnetic agglomerates in the process of the second magnetic separation, so as to improve the yield of the two-stage magnetic separation of the iron concentrate; in addition, these magnetic seeds can reduce the mechanical inclusions of non-magnetic minerals in the process of the first magnetic separation, so as to improve the separation accuracy.

[0053] The first preset mass ratio includes but is not limited to 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, 11:100, 12:100, 13:100, 14:100 or 15:100.

[0054] The second preset mass ratio includes but is not limited to 15:100, 16:100, 17:100, 18:100, 19:100, 20:100, 21:100, 22:100, 23:100, 24:100 or 25:100.

[0055] It should be noted that when the first preset mass ratio is greater than 15:100, there will be a large number of magnetic seeds in the red mud iron tailings, although these magnetic seeds can improve the efficiency of the first magnetic separation and the yield of the first iron concentrate, but they will also increase the inclusions of gangue minerals in the iron tailings, thereby making the gangue mineral inclusions of the first iron concentrate more serious, resulting in a decrease in the TFe content of the iron concentrate. When the first preset mass ratio is less than 5:100, the content of magnetic seeds in the red mud iron tailings will be less, and due to the insufficient number of magnetic seeds, it is difficult to form sufficient magnetic chains or magnetic agglomerates, thereby resulting in a decrease in the yield of the iron concentrate in the first magnetic separation.

[0056] It should be noted that, in the case that the second preset mass ratio is greater than 25:100, a large amount of magnetic seeds will exist in the roughing tailings. Although these magnetic seeds help to improve the efficiency of the second magnetic separation and the yield of the second iron concentrate, they will also increase the inclusions of gangue minerals in the roughing tailings, resulting in the problem of increased gangue mineral inclusions in the second iron concentrate and reduced TFe content of the second iron concentrate. In the case that the second preset mass ratio is less than 15:100, the content of magnetic seeds in the roughing tailings will be small, and a small amount of magnetic seeds cannot be arranged in a directional manner to form sufficient magnetic chains / magnetic agglomerates, thereby resulting in reduced yield and recovery of the iron concentrate obtained by the second magnetic separation.

[0057] In some optional embodiments, the magnetic field strength of the first magnetic separation is 0.6T to 1.2T; and / or the magnetic field strength of the second magnetic separation is 1.3T to 1.6T.

[0058] In these embodiments, the first magnetic separation with a magnetic field strength of 0.6T to 1.2T can promote the directional arrangement of magnetic seeds to form magnetic chains / magnetic agglomerates during the first magnetic separation, so as to improve the yield and TFe content of the iron concentrate obtained by the first magnetic separation. In addition, the second magnetic separation with a magnetic field strength of 1.3T to 1.6T can promote the directional arrangement of magnetic seeds to form magnetic chains / magnetic agglomerates during the second magnetic separation, so as to improve the yield and TFe content of the iron concentrate obtained by the second magnetic separation.

[0059] The magnetic field strength of the first magnetic separation includes but is not limited to 0.6T, 0.7T, 0.8T, 0.9T, 1.0T, 1.1T or 1.2T.

[0060] The magnetic field strength of the second magnetic separation includes but is not limited to 1.30T, 1.35T, 1.40T, 1.45T, 1.50T, 1.55T or 1.60T.

[0061] It should be noted that, in the case that the magnetic field strength of the first magnetic separation is greater than 1.2T, the magnetic field strength of the first magnetic separation is too large, which will cause non-magnetic minerals to mix into the first iron concentrate to form inclusions during the first magnetic separation, thereby reducing the TFe content of the first iron concentrate; in the case that the magnetic field strength of the first magnetic separation is less than 0.6T, the magnetic field strength of the first magnetic separation is too small, which will cause insufficient magnetic attraction during the first magnetic separation, thereby causing part of the first iron concentrate to enter the roughing tailings, resulting in reduced yield of the first iron concentrate and the purpose of recovering fine particle size iron minerals in the red mud iron tailings cannot be achieved.

[0062] It should be noted that when the magnetic field strength of the second magnetic separation is greater than 1.6T, the magnetic field strength of the second magnetic separation is too large, which can cause non-magnetic minerals to mix into the second iron concentrate to form inclusions during the second magnetic separation process, thereby reducing the TFe content of the second iron concentrate; when the magnetic field strength of the second magnetic separation is less than 1.3T, the magnetic field strength of the second magnetic separation is too small, which can cause insufficient magnetic attraction of the second magnetic separation, thereby causing part of the second iron concentrate to enter the roughing tailings, reducing the yield of the second iron concentrate, and failing to achieve the purpose of recovering fine particle size iron minerals in the red mud iron separation tailings.

[0063] In some optional embodiments, the first magnetic separation and the second magnetic separation both use steel rod magnetic aggregation medium as a separation carrier, the diameter of the steel rod magnetic aggregation medium for the first magnetic separation is 2mm to 3mm, and the diameter of the steel rod magnetic aggregation medium for the second magnetic separation is 1.5mm to 2.0mm.

[0064] In these embodiments, the first magnetic separation with a diameter of 2mm to 3mm of the steel rod magnetic aggregation medium can promote the better directional arrangement of the magnetic seeds to form magnetic chains / magnetic agglomerates during the first magnetic separation process, so as to improve the yield and TFe content of the iron concentrate obtained by the first magnetic separation; in addition, the second magnetic separation with a diameter of 1.5mm to 2.0mm of the steel rod magnetic aggregation medium can promote the better directional arrangement of the magnetic seeds to form magnetic chains / magnetic agglomerates during the second magnetic separation process, so as to improve the yield and TFe content of the iron concentrate obtained by the second magnetic separation.

[0065] The diameter of the steel rod magnetic aggregation medium for the first magnetic separation includes but is not limited to 2.0mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm or 3.0mm.

[0066] The diameter of the steel rod magnetic aggregation medium for the second magnetic separation includes but is not limited to 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm or 2.0mm.

[0067] It should be noted that when the diameter of the steel rod magnetic aggregation medium for the first magnetic separation is greater than 3.0mm, the induced magnetic field strength of the first magnetic separation is too small, which can cause insufficient magnetic attraction of the first magnetic separation, thereby causing part of the first iron concentrate to enter the roughing tailings, affecting the yield of the first iron concentrate; when the diameter of the steel rod magnetic aggregation medium for the first magnetic separation is less than 2.0mm, the magnetic field strength of the first magnetic separation is too large, which can cause non-magnetic minerals to mix into the first iron concentrate to form inclusions during the first magnetic separation process, thereby reducing the TFe content of the first iron concentrate.

[0068] It should be noted that when the diameter of the steel rod magnetic aggregation medium of the second magnetic separation is greater than 2.0 mm, the induced magnetic field strength of the second magnetic separation will decrease, resulting in that the magnetic force is not enough to retain part of the second iron concentrate, so that it is mixed into the roughing tailings, thereby reducing the yield of the second iron concentrate. When the diameter of the steel rod magnetic aggregation medium of the second magnetic separation is less than 1.5 mm, the magnetic field strength of the second magnetic separation will be too large, which will cause the non-magnetic minerals to be mixed into the second iron concentrate to form inclusions during the second magnetic separation process, thereby reducing the TFe content of the second iron concentrate, and also reducing the processing capacity of the magnetic separator and increasing the difficulty of discharging the magnetic aggregation medium.

[0069] In some optional embodiments, the preset recovery process includes at least one of the following: table gravity separation, screening, and magnetic separation process.

[0070] In these embodiments, the mixed iron concentrate is separated and recovered by using the preset recovery process including at least one of the table gravity separation, screening, and magnetic separation process, so that the magnetic seeds can be fully dissociated and efficiently recovered, the activity and quantity of the magnetic seeds in the overall process are maintained, and the magnetic seeds are prevented from interfering with the recovery of iron minerals in the iron tailings and from being lost in the tailings.

[0071] It should be noted that when the preset recovery process is table gravity separation, the parameters of the gravity separation are as follows: the table slope is 1.0° to 2.2°; when the preset recovery process is screening, the screen aperture used in the screening is 0.075 mm to 0.079 mm; and when the preset recovery process is magnetic separation, the magnetic field strength of the magnetic separation is 0.15 T to 0.35 T.

[0072] In some optional embodiments, the mass concentration of the roughing raw material is 18% to 25%; and / or The iron content of the red mud iron tailings is 18% to 38%; and the particle size of the iron tailings is ≤0.074 mm.

[0073] In these embodiments, the roughing raw material with a mass concentration of 18% to 25% helps the magnetic seeds and iron minerals to fully disperse and collide, so that the magnetic seeds are arranged in a magnetic chain or magnetic agglomerate in a directional manner, thereby improving the yield and iron content of the iron concentrate in the first magnetic separation. In addition, the red mud iron tailings with an iron content of 18% to 38% and a particle size of ≤0.074 mm ensure that the iron minerals are sufficient and the gangue minerals are fine, which is beneficial to obtaining high-iron-content and high-value iron concentrate through two-stage magnetic separation.

[0074] The mass concentration of the roughing raw material includes but is not limited to 18%, 19%, 20%, 21%, 22%, 23%, 24%, or 25%.

[0075] The iron content of the red mud tailings includes, but is not limited to: 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 30%, 35%, or 38%.

[0076] It should be noted that when the mass concentration of the roughing raw material exceeds 25%, the viscosity increases, affecting the dispersibility of iron minerals and causing a decrease in the TFe content of the first iron concentrate. When the mass concentration of the roughing raw material is below 18%, although it can improve the dispersibility of iron minerals and increase the TFe content of the first iron concentrate, the iron mineral yield is low, requiring multiple processing steps, which increases the processing steps.

[0077] It should be noted that when the iron content of the red mud iron tailings is less than 18%, the iron mineral content is reduced accordingly, which affects the effect of the subsequent two-stage magnetic separation. This results in the iron concentrate being separated with a low iron content and lacking economic value for development and utilization. Conversely, if the iron content of the red mud iron tailings exceeds 38%, the high iron mineral content will increase the difficulty of the two-stage magnetic separation, which will also affect the separation effect.

[0078] The present application is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national / industry standards; if there is no corresponding national / industry standard, they are performed according to general international standards, conventional conditions, or conditions recommended by the manufacturer.

[0079] Example 1 Fine-grained red mud tailings from a certain area in Henan Province were selected, with an iron (TFe) content of 30.40%. These red mud tailings were obtained through hydrocyclone gravity separation. The main useful minerals in these tailings are hematite and goethite, while the gangue minerals are mainly diaspore, sodium silicate slag, and quartz. The particle size of these red mud tailings is less than 0.048 mm.

[0080] like Figure 1 As shown, a method for extracting iron from fine-grained red mud tailings, wherein the iron content of the red mud tailings is ≥18%, includes: S1. The magnetic seeds and red mud iron tailings are mixed in a first preset mass ratio to obtain roughing raw materials; S2. The roughing raw material is subjected to the first magnetic separation to obtain the first iron concentrate and the roughing tailings; S3. The magnetic seeds and roughing tailings are mixed in a second preset mass ratio to obtain scavenging raw materials; S4. The scavenged raw materials are subjected to a second magnetic separation to obtain a second iron concentrate and processed tailings; S5. Combine the first iron concentrate and the second iron concentrate to obtain a mixed iron concentrate; S6. The mixed iron concentrate is subjected to magnetic seed recovery according to a preset recovery process to obtain magnetic seeds and an iron concentrate.

[0081] The particle size of the magnetic seeds is 0.08 mm to 1.00 mm.

[0082] The magnetic seeds include fine-particle magnetic seeds, the mass of the fine-particle magnetic seeds being 35.22% of the total mass of the magnetic seeds; and the particle size of the fine-particle magnetic seeds being ≤0.1 mm.

[0083] The magnetic seeds are natural iron minerals magnetite; The first preset mass ratio is 12.52:100; The second preset mass ratio is 20.57:100.

[0084] The magnetic field strength of the first magnetic separation is 0.90 T; The magnetic field strength of the second magnetic separation is 1.35 T.

[0085] Both the first magnetic separation and the second magnetic separation use steel rod magnetic aggregation media as a separation carrier, the diameter of the steel rod magnetic aggregation media used in the first magnetic separation is 2 mm, and the diameter of the steel rod magnetic aggregation media used in the second magnetic separation is 1.5 mm.

[0086] The mass concentration of the roughing raw material is 21.85%.

[0087] The preset recovery process is a magnetic separation process, and the magnetic field strength of the magnetic separation is 0.20 T.

[0088] Example 2 Compared with Example 1, the differences of the present example are as follows, and the rest are the same: The fine-particle red mud iron tailings of red mud from a certain place in Guangxi are selected, the iron (TFe) content of which is 21.42%, and the fine-particle red mud iron tailings are magnetic tailings. The main useful minerals in the fine-particle red mud iron tailings are hematite and aluminum goethite, and the gangue minerals are mainly sodium silicon slag, diaspore, kaolinite and chlorite, etc. The particle size of the fine-particle red mud iron tailings is less than 0.032 mm.

[0089] The mass of the fine-particle magnetic seeds is 41.57% of the total mass of the magnetic seeds.

[0090] The magnetic seeds are artificial synthetic iron minerals silicon iron powder; The first preset mass ratio is 8.57:100; The second preset mass ratio is 23.41:100.

[0091] The magnetic field strength of the first magnetic separation is 1.15 T; The magnetic field strength of the second magnetic separation is 1.50 T.

[0092] The diameter of the steel rod magnetic medium separated by the first magnetic separation is 2.5 mm, and the diameter of the steel rod magnetic medium separated by the second magnetic separation is 2.0 mm.

[0093] The mass concentration of the roughing raw material is 24.71%.

[0094] The preset recovery process is a screening process, and the screen mesh aperture used in the screening process is 0.076 mm.

[0095] Example 3 Compared with Example 1, the differences of the present example are as follows, and the rest are the same: The fine particle grade red mud iron separation tailings of red mud from a certain place in Shanxi Province are selected, and the iron (TFe) content is 37.57%. The red mud iron separation tailings are magnetic separation tailings. The main useful mineral in the red mud iron separation tailings is hematite, and the gangue minerals are mainly sodium silicon slag, gibbsite, hydrous soft stone, quartz, rutile and anatase, etc. The particle size of the red mud iron separation tailings is less than 0.032 mm.

[0096] The mass of the fine particle grade magnetic seeds is 29.45% of the total mass of the magnetic seeds.

[0097] The magnetic seeds are natural iron minerals ilmenite; The first preset mass ratio is 12.33:100; The second preset mass ratio is 22.31:100.

[0098] The magnetic field strength of the first magnetic separation is 0.75 T; The magnetic field strength of the second magnetic separation is 1.45 T.

[0099] The diameter of the steel rod magnetic medium separated by the first magnetic separation is 3 mm, and the diameter of the steel rod magnetic medium separated by the second magnetic separation is 2.0 mm.

[0100] The mass concentration of the roughing raw material is 18.59%.

[0101] The preset recovery process is a table gravity separation process, and the table bed slope is 1.5°.

[0102] Example 4 Compared with Example 1, the differences of the present example are as follows, and the rest are the same: The fine particle grade red mud iron separation tailings of red mud from a certain place in Shandong Province are selected, and the iron (TFe) content is 36.08%. The red mud iron separation tailings are gravity separation tailings. The main useful minerals in the red mud iron separation tailings are hematite and aluminian goethite, and the gangue minerals are mainly sodium silicon slag, gibbsite, hydrous soft stone, quartz and anatase, etc. The particle size of the red mud iron separation tailings is less than 0.060 mm.

[0103] The mass of the fine particle level magnetic seed is 39.26% of the total mass of the magnetic seed.

[0104] The magnetic seed is a natural iron ore hematite; The first preset mass ratio is 13.52:100; The second preset mass ratio is 21.42:100.

[0105] The magnetic field strength of the first magnetic separation is 1.05T; The magnetic field strength of the second magnetic separation is 1.55T.

[0106] The diameter of the steel rod magnetic medium for the first magnetic separation is 2.8mm, and the diameter of the steel rod magnetic medium for the second magnetic separation is 1.80mm.

[0107] The preset recovery process is a screening process, and the screen mesh aperture used in the screening process is 0.078mm.

[0108] The mass concentration of the roughing raw material is 20.09%.

[0109] Example 5 Compared with Example 1, the differences of the present embodiment are as follows, and the rest are the same: The fine particle level red mud iron separation tailings of red mud from a certain place in Yunnan are selected, and the iron (TFe) content is 26.49%. The red mud iron separation tailings are gravity separation tailings. The main useful minerals in the red mud iron separation tailings are hematite and limonite, and the gangue minerals are mainly sodium silicon slag, diaspore, boehmite, quartz and anatase. The particle size of the red mud iron separation tailings is less than 0.040mm.

[0110] The mass of the fine particle level magnetic seed is 42.55% of the total mass of the magnetic seed.

[0111] The magnetic seed is an artificial synthetic iron mineral magnetic ferrite.

[0112] The first preset mass ratio is 11.39:100; The second preset mass ratio is 22.39:100.

[0113] The magnetic field strength of the first magnetic separation is 0.95T; The magnetic field strength of the second magnetic separation is 1.50T.

[0114] The diameter of the steel rod magnetic medium for the first magnetic separation is 2.5mm, and the diameter of the steel rod magnetic medium for the second magnetic separation is 1.90mm.

[0115] The mass concentration of the roughing raw material is 23.51%.

[0116] The preset recovery process is a magnetic separation process, and the magnetic field strength of the magnetic separation is 0.30T.

[0117] Comparative Example 1 The difference between this comparative example and Example 1 is as follows, and the rest are the same: The technology of prior art (1) in the background art was used for processing.

[0118] Comparative Example 2 The difference between this comparative example and Example 2 is as follows, and the rest are the same: The technology of prior art (1) in the background art was used for processing.

[0119] Comparative Example 3 The difference between this comparative example and Example 3 is as follows, and the rest are the same: The technology of prior art (1) in the background art was used for processing.

[0120] Comparative Example 4 The difference between this comparative example and Example 4 is as follows, and the rest are the same: The technology of prior art (1) in the background art was used for processing.

[0121] Comparative Example 5 The difference between this comparative example and Example 5 is as follows, and the rest are the same: The technology of prior art (1) in the background art was used for processing.

[0122] Comparative Example 6 The difference between this comparative example and Example 1 is as follows, and the rest are the same: Two-stage magnetic separation was not performed using magnetic seeds.

[0123] Comparative Example 7 The difference between this comparative example and Example 1 is as follows, and the rest are the same: The first preset mass ratio was 2.32:100; The second preset mass ratio was 6.77:100.

[0124] Comparative Example 8 The difference between this comparative example and Example 1 is as follows, and the rest are the same: The first preset mass ratio was 17.32:100; The second preset mass ratio was 28.77:100.

[0125] Comparative Example 9 The difference between this comparative example and Example 1 is as follows, and the rest are the same: The mass of the fine particle grade magnetic seeds was 10% of the total mass of the magnetic seeds.

[0126] Comparative Example 10 Compared with Example 1, the differences of the present comparative example are as follows, and the rest are the same: The mass of the fine particle level magnetic seed is 60% of the total mass of the magnetic seed.

[0127] Comparative Example 11 Compared with Example 1, the differences of the present comparative example are as follows, and the rest are the same: The magnetic field strength of the first magnetic separation and the second magnetic separation is 0.90T.

[0128] Related experiments and effect data: The iron concentrate and tailings of each example and comparative example are collected respectively, and the iron content and yield are counted, and the results are shown in Table 1.

[0129] Table 1 Iron content and yield of iron concentrate and tailings of each example and comparative example

[0130] As can be seen from Table 1, the method for extracting iron from fine particle level red mud iron tailings provided by the present application can effectively improve the total recovery rate of iron in red mud tailings to more than 45.82% by means of precise quantitative addition of magnetic seeds, fine regulation of the micro-interface of the slurry system, hierarchical enhancement of magnetic agglomeration, and recycling of magnetic seeds, and ensure that the iron content in the iron concentrate is not less than 46.33%.

[0131] Compared with Examples 1 to 5, Comparative Examples 1 to 5 use traditional processing technology, and the total recovery rate and iron content of the iron concentrate are relatively low. In contrast, the present application uses comprehensive magnetic separation technology such as precise quantitative addition of magnetic seeds, hierarchical enhancement of magnetic agglomeration, and recycling of magnetic seeds, which significantly improves the recovery rate and iron content of the iron concentrate in the red mud iron tailings.

[0132] Compared with Example 1, Comparative Example 6 does not use magnetic seeds for two-stage magnetic separation, and Comparative Example 7 uses magnetic seeds with a lower mass ratio for two-stage magnetic separation, which results in poor recovery rate and iron content of the separated iron concentrate; in addition, Comparative Example 8 uses magnetic seeds with a high mass ratio for two-stage magnetic separation, which can obtain iron concentrate with high yield, but the iron content of the obtained iron concentrate decreases greatly.

[0133] Compared with Example 1, the low proportion of fine particle level magnetic seeds used in Comparative Example 9 makes it difficult for the magnetic seeds to be arranged in a chain or magnetic aggregate, resulting in a low yield of iron concentrate from the red mud iron tailings. In addition, the high proportion of fine particle level magnetic seeds used in Comparative Example 10 can make the magnetic seeds arrange in a more compact chain or magnetic aggregate, thereby improving the yield of iron concentrate. However, the use of such fine particle level magnetic seeds can cause severe inclusions in the iron concentrate, resulting in a slight decrease in the TFe content of the iron concentrate and increasing the difficulty of the preset recovery process of the magnetic seeds. In Comparative Example 11, the same magnetic field strength is used in the first and second magnetic separation, which can obtain a first iron concentrate with high yield and high iron content. However, the second magnetic separation faces difficulties in recovering weakly magnetic iron minerals from the roughing tailings, which directly leads to a decrease in the yield and iron content of the second iron concentrate, resulting in a decrease in the yield of the iron concentrate.

[0134] In summary, the method for extracting iron from fine particle level red mud iron tailings provided by the embodiments of the present application can significantly improve the recovery rate of iron minerals in the iron tailings by constructing a closed-loop separation system of “pre-dispersion-roughing-scavenging-magnetic seed circulation” based on the magnetic seed induced hierarchical magnetic aggregation technology.

[0135] In addition, the method for extracting iron from fine particle level red mud iron tailings provided by the embodiments of the present application can improve the difficulties of magnetization and magnetic force capture of fine particle level iron minerals in the red mud iron tailings in the magnetic separation process by using precise quantitative addition of magnetic seeds, micro-interface regulation of the slurry system, hierarchical strengthening of magnetic aggregation, and closed-loop regeneration of magnetic seeds. The magnetic chain / magnetic aggregate formed by the directional arrangement of the magnetic seeds can improve the yield of the two-stage magnetic separation iron concentrate, and solve the technical problems of low yield and low recovery rate of iron concentrate in the recovery of iron minerals in the existing technology.

[0136] In addition, the method for extracting iron from fine particle level red mud iron tailings provided by the embodiments of the present application can effectively enhance the fluidity of the iron tailings and the roughing tailings by using fine magnetic seeds, solve the problem of mechanical inclusions of non-magnetic minerals in the two-stage magnetic separation process, and further improve the precision of the magnetic separation, so that the iron content of the iron concentrate can be significantly improved, thereby overcoming the challenges of poor grade of iron concentrate and low comprehensive utilization rate in the recovery of iron minerals in the existing technology.

[0137] In addition, the method for extracting iron from the fine particle grade red mud iron tailings provided by the embodiment of the present application further integrates a magnetic seed recovery step, realizes accurate separation of the magnetic seeds and iron minerals in the first iron concentrate and the second iron concentrate, effectively prevents loss of the magnetic seeds and adverse effects of the magnetic seeds on the iron content indicators of the two types of iron concentrates, ensures efficient recovery of the iron minerals, and realizes recycling of the magnetic seeds. Overall, the method has many advantages such as high separation efficiency, low cost, and significantly improved comprehensive utilization rate.

[0138] In addition, the method for extracting iron from the fine particle grade red mud iron tailings provided by the embodiment of the present application is based on a closed-loop separation system of 'pre-dispersion - roughing - scavenging - magnetic seed circulation', and through physical screening means of magnetic separation, not only can the efficient recovery of iron minerals in the red mud iron tailings be realized to realize the resource utilization of red mud solid waste and reduce the storage risk of red mud solid waste. In addition, the method does not produce pollutants, has the advantages of low cost, high economic benefit, high resource utilization rate, mature and stable process, and environmental friendliness.

[0139] The above is only a specific embodiment of the present application, which enables those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined in the present application can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown in the present application, but will conform to the widest range consistent with the principles and novel features claimed in the present application.

Claims

1. A method for extracting iron from fine-grained red mud tailings, wherein the iron content of the red mud tailings is ≥18%, the method comprising: The magnetic seeds and the iron tailings are mixed in a first preset mass ratio to obtain the roughing raw material. The roughing raw material is subjected to a first magnetic separation to obtain a first iron concentrate and roughing tailings; The magnetic seeds and the roughing tailings are mixed in a second preset mass ratio to obtain scavenging raw materials; The scavenged raw material is subjected to a second magnetic separation to obtain a second iron concentrate and processed tailings. The first iron concentrate and the second iron concentrate are combined to obtain a mixed iron concentrate; The mixed iron concentrate is subjected to magnetic seed recovery according to the preset recovery process to obtain magnetic seeds and iron concentrate.

2. The method according to claim 1, characterized in that, The magnetic seeds have a particle size of 0.08 mm to 1.00 mm.

3. The method according to claim 1 or 2, characterized in that, The magnetic seeds include fine-grained magnetic seeds, the mass of which is 20% to 50% of the total mass of the magnetic seeds; the particle size of the fine-grained magnetic seeds is ≤0.1mm.

4. The method according to claim 1 or 2, characterized in that, The magnetic seeds are natural iron minerals and / or artificially synthesized iron minerals.

5. The method according to claim 4, characterized in that, When the magnetic seed is a natural iron mineral, the natural iron mineral includes at least one of the following: magnetite, hematite, siderite, and ilmenite; and / or When the magnetic seed is a synthetic iron mineral, the synthetic iron mineral includes ferrosilicon powder and / or magnetic ferrite.

6. The method according to claim 1, characterized in that, The first preset mass ratio is (5 to 15):100; and / or The second preset mass ratio is (15 to 25):

100.

7. The method according to claim 1, characterized in that, The magnetic field strength for the first magnetic separation is 0.6T to 1.2T; and / or The magnetic field strength for the second magnetic separation is 1.3T to 1.6T.

8. The method according to claim 1, characterized in that, Both the first magnetic separation and the second magnetic separation use steel rod magnetic media as the separation carrier. The diameter of the steel rod magnetic media in the first magnetic separation is 2 mm to 3 mm, and the diameter of the steel rod magnetic media in the second magnetic separation is 1.5 mm to 2.0 mm.

9. The method according to claim 1, characterized in that, The preset recycling process includes at least one of the following: shaking table gravity separation, screening and magnetic separation processes.

10. The method according to claim 1, characterized in that, The mass concentration of the roughing raw material is 18% to 25%; and / or The iron content of the red mud tailings is 18% to 38%, and the particle size of the tailings is ≤0.074mm.

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