A method for enhanced recovery of iron minerals from high-iron red mud

Abstract

The application relates to a method for strengthening and recovering iron minerals from high-iron red mud, belonging to the technical field of industrial solid waste treatment, and the method comprises the following steps: conveying a bottom flow slurry of the Bayer process high-iron red mud to a pretreatment tank, diluting the slurry by adding recycled filter water, obtaining pretreated slurry, dissolving a surface adjusting agent and a flocculating agent in water to prepare a working solution, mechanically activating a magnetization enhancer to obtain the magnetization enhancer with uniform particle size, adding a certain amount of the surface adjusting agent solution into the pretreated slurry, carrying out dispersion treatment, obtaining dispersed slurry, and the like; by adding the surface adjusting agent into the red mud system, the application realizes effective dissociation of the iron minerals and aluminum, titanium minerals and gangue minerals such as silicon and calcium, introduces the flocculating agent, makes the target minerals form large particle flocs, adds the magnetization enhancer, makes the magnetization enhancer be closely combined with the iron mineral flocs, improves the selectivity and enrichment efficiency of the subsequent magnetic separation process, realizes efficient enrichment and separation of the iron minerals in the red mud, and promotes red mud reduction and resource utilization.

Description

Technical Field

[0001] This invention belongs to the field of industrial solid waste treatment technology, and in particular relates to a method for enhanced recovery of iron minerals from high-iron red mud. Background Technology

[0002] Magnetic separation is the primary process for recovering iron from red mud. This technology boasts advantages such as simple process and controllable cost, making it a mainstream choice in industrial applications. In red mud, hematite is closely associated with minerals such as aluminum, silicon, and calcium, forming a stable, fine-grained disseminated structure. Conventional magnetic separation processes rely on complex multi-stage, multi-process operations to achieve partial iron recovery. However, because this disseminated structure is not fundamentally altered, the resulting iron concentrate grade is generally below 55%, with high impurity content and significant loss of fine-grained iron minerals, resulting in a low overall iron recovery rate. To overcome the bottlenecks of existing processes and achieve efficient and high-quality iron resource recovery from red mud, it is urgent to develop new technologies that can fundamentally alter the mineral disseminated characteristics and enhance the selective separation of iron minerals.

[0003] The combined process of "magnetic separation followed by magnetic separation" used in patent [CN101254481A] results in a low iron recovery rate due to its lengthy process and poor adaptability to particle size. Patent [CN101648159A] employs a shorter process of "medium-level magnetic separation + vertical ring pulsed high-gradient magnetic separation," which, through precise control of magnetic field parameters, can directly obtain iron concentrate with a grade ≥54% from red mud; however, its effectiveness is highly dependent on high-performance magnetic separation equipment and stable operating conditions. Patent [CN116832946A] uses multi-stage magnetic separation of "weak magnetic separation-coarse separation-fine separation-sweeping" combined with simultaneous sand extraction, obtaining iron concentrate with a grade of 50-55% while recovering approximately 5% sand product. Patent [CN118291750A] uses a cyclical separation structure of "gravity separation-magnetic separation-re-gravity separation" to process coarse and fine particle sizes, obtaining iron concentrate with a comprehensive grade of approximately 50%. These multi-stage combined processes generally suffer from long process flows, numerous process parameters, and difficulty in precise control, making them challenging for practical industrial applications. Summary of the Invention

[0004] In view of the aforementioned shortcomings and deficiencies of existing technologies, this invention provides a method for enhanced recovery of iron minerals from high-iron red mud. By adding a surface modifier to the red mud system, the zeta potential of the mineral surface is altered, enhancing the electrostatic repulsion between particles and achieving effective dissociation of iron minerals from aluminum, titanium, and gangue minerals such as silicon and calcium. Furthermore, a flocculant with specific recognition and adsorption functions for iron minerals is introduced, promoting the formation of large flocs of the target minerals through surface bridging. Finally, a magnetization enhancer is added to the system, allowing it to tightly bind with the iron mineral flocs and form a composite floc with high magnetic response characteristics, improving the selectivity and enrichment efficiency of subsequent magnetic separation processes. This method can achieve efficient enrichment and separation of iron minerals in red mud, promoting the reduction and resource utilization of red mud.

[0005] Includes the following steps:

[0006] Step (1) Pretreatment: The Bayer process high-speed iron red mud bottom flow slurry obtained from the sedimentation process is transported to the pretreatment tank, and recycled filter water is added under mechanical stirring to dilute it and obtain the pretreated slurry.

[0007] Step (2) Preparation of medicine:

[0008] Dissolve the surface conditioner in water to prepare a surface conditioner solution for later use;

[0009] The flocculant is dissolved in water and activated at a certain temperature with a flocculant activator to prepare a flocculant working solution for later use;

[0010] The magnetization enhancer is mechanically activated to obtain a magnetization enhancer with uniform particle size for later use.

[0011] Step (3) Potential control: Add a certain amount of surface conditioning agent solution from step (2) to the pretreatment slurry from step (1) to change the Zeta potential of the mineral surface, and disperse the slurry at a certain stirring speed to obtain a dispersed slurry and enhance the electrostatic repulsion between particles.

[0012] Step (4) Targeted flocculation treatment: Add a certain amount of flocculant working liquid from step (2) to the dispersed slurry obtained in step (3), and carry out flocculation treatment at a certain stirring speed to obtain flocculated slurry;

[0013] Step (5) Selective magnetization treatment: The flocculated slurry obtained in step (4) is transported to the magnetic separator, and the selection operation is carried out according to the quality requirements of the target iron concentrate: If high-grade iron concentrate is required, the magnetizing enhancer obtained in step (2) is added in batches during the transportation process to fully mix with the slurry to obtain the slurry to be magnetically separated; If low-grade iron concentrate is required, the flocculated slurry obtained in step (4) is directly used as the slurry to be magnetically separated.

[0014] Step (6) Magnetic separation: The slurry to be magnetically separated obtained in step (5) is subjected to magnetic separation to obtain magnetic concentrate slurry and magnetic tailings slurry. The magnetic tailings slurry is returned to the pretreatment tank in step (1).

[0015] Step (7) Concentration, Dehydration and Recycling: First, according to the quality requirements of the target iron concentrate, the magnetic separation concentrate slurry obtained in step (6) is concentrated to a suitable solid content by a thickener, and then dehydrated by a filter press to obtain iron concentrate and filter water; the filter water is returned to the pretreatment tank in step (1) for dilution of Bayer process high iron red mud bottom flow slurry.

[0016] In step (1), the mineral type of the Bayer process high-iron red mud bottom flow slurry is either gibbsite or gibbsite, and the Fe2O3 content is not less than 30%.

[0017] In step (1), the pretreatment tank is equipped with a multi-stage stirring system. The upper layer uses inclined blade turbine blades to quickly mix the slurry and reagents to achieve macroscopic homogenization. The middle layer uses folded blade or frame blades to ensure sufficient contact and surface reaction between the reagents and mineral particles. The lower layer is equipped with anchor or ribbon blades near the bottom of the tank to prevent the deposition of high-density solid particles and maintain the overall concentration stability of the tank.

[0018] The solid content of the pretreated slurry in step (1) is 200~400g / L.

[0019] In step (2),

[0020] The surface modifier is one or more of surfactant-type, inorganic electrolyte-type, and polymer-type compounds, including one or more of sulfonates, phosphates, silicates, sulfates, polyethers, polysaccharides, and their modifiers, with an effective content ≥60% and an addition amount of 0.1%~10% of the dry mass fraction of red mud;

[0021] The flocculant is one or more of carboxylates, sulfonates / sulfates, hydroxamic acid, amines, and starch compounds, with an effective content ≥75%, and the addition amount is 0.1%~10% of the dry mass fraction of red mud.

[0022] The flocculant activator is a non-polar hydrocarbon oil substance, and the amount added is 0.1% to 10% of the dry mass fraction of red mud.

[0023] The magnetization enhancer is an industrial iron-containing waste material, selected from one or more of magnetite tailings, steel plant sludge, or iron filings, and the amount added is 1% to 5% of the dry mass of red mud.

[0024] In step (2), the mechanical activation process of the magnetizing enhancer is carried out in a high-energy planetary ball mill, the ball milling speed is controlled at 200~800 rpm, the activation time is 30~120 min, and the particle size of the obtained magnetizing enhancer meets the requirement that particles with a size ≤74μm account for more than 90% of its total mass.

[0025] The stirring speed in steps (3) and (4) is 100~200 r / min, and the dispersion treatment time in step (3) and the flocculation treatment time in step (4) are 10~30 min.

[0026] In step (6), the magnetic separation equipment is a wet high-intensity magnetic separator with a magnetic field strength of 5000~20000Oe, a pulse frequency of 10~80Hz, and one or more magnetic separations.

[0027] In step (7), the iron concentrate has a TFe content of ≥60% and an Al2O3 content of ≤3% by mass percentage, and the iron recovery rate of a single treatment is ≥60%.

[0028] In step (7), the thickener is a high-efficiency deep cone thickener and the filter press is a plate and frame filter press.

[0029] The beneficial effects of this invention are:

[0030] (1) This invention uses a three-step synergistic process of potential regulation, targeted flocculation and magnetic seed enhancement, which can be closely coupled with the existing red mud treatment process. By introducing key regulation links, the separation efficiency of iron minerals in red mud can be significantly enhanced. It has the outstanding advantage of strong adaptability and is easy to promote and apply in industrial production.

[0031] (2) This invention utilizes surface modifiers to regulate the potential of the slurry, thereby changing the Zeta potential of various minerals on the surface of red mud. By enhancing the electrostatic repulsion between particles, it effectively achieves deep dissociation and stable dispersion of minerals, creating crucial physicochemical conditions for subsequent selective enrichment.

[0032] (3) The present invention uses a targeted flocculant that has specific recognition ability for iron minerals, which can promote the selective aggregation of iron ore particles to form dense and uniform flocs, reduce the inclusion of gangue minerals such as aluminosilicates, and achieve precise and directional enrichment of iron elements.

[0033] (4) This invention introduces a magnetization enhancer to magnetize the iron mineral flocs and magnetic medium to form a composite flocs with high magnetic response characteristics, thereby improving the magnetic difference between the target product and the tailings and significantly improving the efficiency of subsequent magnetic separation and the grade of concentrate.

[0034] (5) This process is highly adaptable to raw materials and can process a variety of types of red mud. At the same time, it has good operational flexibility. By flexibly adjusting the reagent system and process parameters, it can be optimized for different raw material properties and product requirements, providing a stable and flexible solution for the large-scale utilization of red mud and resources. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the process for the enhanced red mud direct magnetic separation method for iron recovery according to the present invention. Detailed Implementation

[0036] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] This invention provides a method for enhanced direct magnetic separation and iron recovery from red mud, comprising the following steps:

[0038] Step (1) Pretreatment: The Bayer process high-speed iron red mud bottom flow slurry obtained from the sedimentation process is transported to the pretreatment tank. Under mechanical stirring conditions, recycled filter water is added for dilution to facilitate the uniform dispersion and reaction of subsequent reagents, avoid particle deposition or separation, and obtain pretreated slurry. This creates good physical conditions for subsequent surface potential control and flocculation treatment. The use of recycled filter water realizes closed-loop water circulation, reduces fresh water consumption and wastewater discharge, and reflects environmental protection design.

[0039] The solid content of the pretreated slurry is 200~400g / L.

[0040] The raw material used in this invention, Bayer process high-iron red mud bottom flow slurry, is boehmite-type or gibbsite-type bauxite high-iron red mud, with an Fe2O3 content of not less than 30%, and no requirements for other components.

[0041] The pretreatment tank used in this invention has a multi-stage stirring system. The upper layer uses inclined blade turbine blades to quickly mix the slurry and reagents to achieve macroscopic homogenization. The middle layer uses folded blade or frame blades to ensure sufficient contact and surface reaction between the reagents and mineral particles. The lower layer is equipped with anchor or ribbon blades near the bottom of the tank to prevent the deposition of high-density solid particles and maintain the overall concentration stability of the tank.

[0042] Step (2) Preparation of medicine:

[0043] The surface modifier is dissolved in water to prepare a surface modifier solution for later use. The surface modifier is one or more of the following: surfactant type, inorganic electrolyte type and polymer type compound, including one or more of sulfonates, phosphates, silicates, sulfates, polyethers, polysaccharides and their modified products, with an effective content ≥60% and an addition amount of 0.1%~10% of the dry mass fraction of red mud.

[0044] The flocculant selectively adsorbs iron minerals. The flocculant is dissolved in water and activated at a certain temperature using a flocculant activator to prepare a working flocculant solution for later use. Pre-activation allows the agent to better react chemically with the mineral surface, improving overall separation efficiency. The flocculant is one or more of carboxylates, sulfonates / sulfates, hydroxamic acids, amines, and starch compounds, with an effective content ≥75%, and is added at 0.1%~10% of the dry weight of red mud. The flocculant activator is a non-polar hydrocarbon oil, added at 0.1%~10% of the dry weight of red mud.

[0045] The magnetization enhancer is an industrial iron-containing waste, selected from one or more of magnetite tailings, steel plant sludge, or iron filings, and the addition amount is 1% to 5% of the dry weight of red mud.

[0046] The mechanical activation process of the magnetizing enhancer is carried out in a high-energy planetary ball mill, with the milling speed controlled at 200-800 rpm and the activation time at 30-120 min. The resulting magnetizing enhancer has particles ≤74 μm accounting for more than 90% of its total mass. This improves the surface activity and dispersibility of the magnetizing enhancer, making it easier to combine with iron mineral flocs to form a highly magnetically responsive composite structure. The use of industrial waste demonstrates resource recycling and reduces costs. The fine particle size after activation ensures uniform distribution and efficient adsorption.

[0047] Step (3) Potential Control: A certain amount of surface modifier solution from step (2) is added to the pretreated slurry from step (1) to reduce the Zeta potential of the mineral surface. The slurry is then dispersed at a stirring speed of 100-200 r / min for 10-30 min to obtain a dispersed slurry, thereby enhancing the electrostatic repulsion between particles. By adding the surface modifier, the Zeta potential of the mineral surface is reduced, and the electrostatic repulsion between particles is enhanced, achieving effective dissociation and stable dispersion of iron minerals with aluminum, titanium minerals, and gangue minerals such as silicon and calcium. This step is the core foundation of the process, changing the embedding structure of minerals in the red mud and creating conditions for subsequent selective flocculation.

[0048] The reaction formula between the surface conditioner and the main minerals in red mud is as follows:

[0049] Fe-OH+X n- →Fe-X 1-n +OH - ;

[0050] Al-OH+X n- →Al-X 1-n +OH - ;

[0051] Ti-OH+X n- →Ti-X 1-n +OH - ;

[0052] Ca 2+ +X n- →Ca-X 2-n ;

[0053] In the formula, X is the general formula for surface modifiers, n is the charge number of the surface modifier, RX is the adsorption layer structure, and R is one of the following elements: iron (Fe), aluminum (Al), titanium (Ti), and calcium (Ca).

[0054] Step (4) Targeted flocculation treatment: A certain amount of the flocculant working solution from step (2) is added to the dispersion slurry obtained in step (3), and flocculation treatment is carried out at a stirring speed of 100~200 r / min for 10~30 min to obtain a flocculent slurry; a flocculant with specific recognition and adsorption function for iron minerals is introduced, which promotes the selective aggregation of fine iron mineral particles through surface bridging to form high-density flocs with dense structure and uniform size. This reduces the inclusion of gangue minerals and achieves precise directional enrichment of iron elements. The activator further enhances the flocculation efficiency.

[0055] The reaction between the flocculant and the iron minerals in the red mud is as follows:

[0056] Fe₂O₃ + Y → Fe-Y + H₂O;

[0057] In the formula, Y is the general formula for flocculants, and Fe-Y is the floc structure.

[0058] Step (5) Selective magnetization treatment: The flocculated slurry obtained in step (4) is transported to the magnetic separator, and the selection operation is carried out according to the quality requirements of the target iron concentrate: if high-grade iron concentrate is required, the magnetizing enhancer obtained in step (2) is added in batches during the transportation process to fully mix with the slurry to obtain the slurry to be magnetically separated; if low-grade iron concentrate is required, the flocculated slurry obtained in step (4) is directly used as the slurry to be magnetically separated; by adding the magnetizing enhancer, the iron mineral flocs are tightly combined with the magnetic medium to form a composite flocculent with high magnetic response characteristics, thereby improving the selectivity and enrichment efficiency of subsequent magnetic separation. This flexible design allows the process to be adjusted according to product requirements, amplifying the magnetic differences between the target product and the tailings.

[0059] Step (6) Magnetic separation: The slurry to be magnetically separated obtained in step (5) is separated by a wet high-intensity magnetic separator. The magnetic field strength is 5000~20000 Oe, the pulse frequency is 10~80Hz, and the number of magnetic separations is one or more times to obtain magnetic concentrate slurry and magnetic tailings slurry. The magnetic tailings slurry is returned to the pretreatment tank in step (1). The magnetic field is used to separate the strongly magnetic iron concentrate from the non-magnetic tailings. Through high gradient design, the separation efficiency is improved, ensuring that high-quality products can be obtained in a single magnetic separation, and simplifying the process.

[0060] Step (7) Concentration, Dehydration and Recycling: First, according to the quality requirements of the target iron concentrate, the magnetic separation concentrate slurry obtained in step (6) is concentrated to a suitable solid content by a thickener, and then dehydrated by a filter press to obtain iron concentrate and filter water; the iron concentrate, by mass percentage, has a TFe content ≥60%, an Al2O3 content ≤3%, and an iron recovery rate of more than 60% per treatment; the filter water is returned to the pretreatment tank in step (1) for dilution of the Bayer process high-iron red mud bottom flow slurry; solid-liquid separation of the concentrate is achieved to obtain dry iron concentrate product, and water resources are recycled to achieve closed-loop circulation of process water within the system. Thickening and filtration ensure product quality while reducing environmental impact.

[0061] Example 1

[0062] In this embodiment, the raw material is gibbsite-type bauxite Bayer process high-iron red mud, and its main chemical components (mass percentage, wt. / %) are: Al2O3 17.82%, CaO 11.79%, SiO2 10.88%, Fe2O3 37.23%, TiO2 4.36%, Na2O 4.88%.

[0063] In this embodiment, sodium silicate is selected as the surface conditioner with an effective content of 95%; octyl hydroxamic acid is selected as the flocculant with an effective content of 82%; industrial kerosene is selected as the flocculant activator; and iron filings are selected as the magnetization enhancer.

[0064] This embodiment specifically includes the following steps:

[0065] The Bayer process high-speed iron red mud bottom flow slurry obtained from the sedimentation process is transported to the pretreatment tank, and diluted with recycled filter water under mechanical stirring to obtain a pretreatment slurry with a solid content of 350 g / L.

[0066] Sodium silicate was dissolved in water to prepare a surface conditioner solution; octyl hydroxamic acid was dissolved in water and, after thorough stirring and activation, was prepared into a flocculant working solution.

[0067] Iron filings were activated for 120 minutes at a ball mill speed of 200 rpm to obtain a magnetization enhancer.

[0068] A surface conditioner solution was added to the pretreated slurry for potential control. The addition amount was 5% of the dry red mud mass fraction, and the dispersion time was 15 min, resulting in a dispersed slurry. The reaction equation for this step is as follows:

[0069] Fe-OH+SiO(OH)3 - →Fe-O-SiO(OH)2 - +H2O;

[0070] A flocculant working solution with a dry red mud mass fraction of 6% was added to the dispersed slurry for flocculation treatment for 15 minutes to obtain a flocculated slurry. In this step, to improve the flocculation effect of the flocculant, industrial kerosene with a dry red mud mass fraction of 3% was added as a flocculant activator.

[0071] The obtained flocculated slurry is transported to the feed pipeline of the magnetic separator, and the magnetizing enhancer is added in four batches, with a total addition amount of 3% of the dry mass fraction of red mud, to obtain the magnetized slurry.

[0072] The obtained magnetized slurry was subjected to magnetic separation under a magnetic field strength of 15000 Oe and a pulse frequency of 50 Hz to obtain magnetic concentrate slurry and magnetic tailings slurry. The number of magnetic separations was one.

[0073] The magnetic separation concentrate slurry is subjected to pressure filtration to obtain iron concentrate and filter water; the filter water is returned to the pretreatment tank for dilution of red mud bottom flow slurry.

[0074] The obtained iron concentrate had a TFe content of 60.23%, an Al2O3 content of 2.52%, and an iron recovery rate of 68.79%.

[0075] Example 2

[0076] In this embodiment, the raw material is gibbsite-type bauxite Bayer process high-iron red mud, and its main chemical components (mass percentage, wt. / %) are: Al2O3 13.82%, CaO 15.79%, SiO2 6.88%, Fe2O3 31.23%, TiO2 5.48%, Na2O 3.17%.

[0077] In this embodiment, sodium hexametaphosphate is selected as the surface conditioner with an effective content of 80%; sodium dodecyl sulfonate is selected as the flocculant with an effective content of 75%; 200# solvent oil is selected as the flocculant activator; and iron filings are selected as the magnetization enhancer.

[0078] The method is the same as in Example 1, except that:

[0079] The solid content of the pretreated slurry is 400 g / L;

[0080] Sodium hexametaphosphate was dissolved in water to prepare a surface conditioner solution; sodium dodecyl sulfonate was dissolved in water and, after thorough stirring and activation, was prepared into a flocculant working solution.

[0081] Iron filings were activated for 60 minutes at a ball mill speed of 450 rpm to obtain a magnetization enhancer.

[0082] The surface conditioner solution was added at 2% of the dry red mud mass fraction, and the dispersion time was 15 min.

[0083] The flocculant working solution was added at 6% of the dry red mud mass fraction, and the flocculation time was 15 min. In this step, to improve the flocculation effect of the flocculant, 1.5% of the dry red mud mass fraction of 200# solvent oil was added as a flocculant activator.

[0084] The flocculated slurry is fed into the magnetic separator feed line, and the magnetizing enhancer is added in four batches, with a total addition amount of 1% of the dry mass fraction of red mud, to obtain the magnetized slurry.

[0085] The magnetized slurry was subjected to magnetic separation under a magnetic field strength of 13000 Oe and a pulse frequency of 60 Hz to obtain magnetic concentrate slurry and magnetic tailings slurry. The number of magnetic separations was one.

[0086] The obtained iron concentrate had a TFe content of 61.57%, an Al2O3 content of 2.74%, and an iron recovery rate of 66.78%.

[0087] Example 3

[0088] In this embodiment, the raw material is gibbsite-type bauxite Bayer process high-iron red mud, and its main chemical composition (mass percentage, wt. / %) is: Al2O3 10.24%, CaO 13.19%, SiO2 9.24%, Fe2O3 47.16%, TiO2 4.96%, Na2O 5.12%.

[0089] In this embodiment, sodium tripolyphosphate is selected as the surface conditioner with an effective content of 80%; sodium dodecyl sulfonate is selected as the flocculant with an effective content of 75%; industrial kerosene is selected as the flocculant activator; and iron filings are selected as the magnetization enhancer.

[0090] The method is the same as in Example 1, except that:

[0091] The solid content of the pretreated slurry is 350 g / L;

[0092] Sodium tripolyphosphate was dissolved in water to prepare a surface conditioner solution; sodium dodecyl sulfonate was dissolved in water and, after thorough stirring and activation, was prepared into a flocculant working solution.

[0093] Iron filings were activated for 60 minutes at a ball mill speed of 450 rpm to obtain a magnetization enhancer.

[0094] The surface conditioner solution was added at 3% of the dry red mud mass fraction, and the dispersion time was 10 min.

[0095] The amount of flocculant working solution added is 5% of the dry red mud mass fraction, and the flocculation time is 10 min. In this step, in order to improve the flocculation effect of the flocculant, 2% of the dry red mud mass fraction of industrial kerosene is added as a flocculant activator.

[0096] The flocculated slurry is fed into the magnetic separator feed line, and the magnetizing enhancer is added in four batches, with a total addition amount of 1% of the dry mass fraction of red mud, to obtain the magnetized slurry.

[0097] The magnetized slurry was subjected to magnetic separation under a magnetic field strength of 11000 Oe and a pulse frequency of 80 Hz to obtain magnetic concentrate slurry and magnetic tailings slurry. The number of magnetic separations was one.

[0098] The obtained iron concentrate had a TFe content of 63.72%, an Al2O3 content of 2.38%, and an iron recovery rate of 65.23%.

[0099] Example 4

[0100] In this embodiment, the raw material is gibbsite-type bauxite Bayer process high-iron red mud, whose main chemical components (mass percentage, wt. / %) are: Al2O3 10.24%, CaO 2.19%, SiO2 3.95%, Fe2O3 63.16%, TiO2 3.15%, Na2O 2.12%.

[0101] In this embodiment, sodium silicate is selected as the surface conditioner with an effective content of 75%; sodium linoleate is selected as the flocculant with an effective content of 88%; industrial diesel oil is selected as the flocculant activator; and iron filings are selected as the magnetization enhancer.

[0102] The method is the same as in Example 1, except that:

[0103] The solid content of the pretreated slurry is 400 g / L;

[0104] Sodium silicate was dissolved in water to prepare a surface conditioner solution; sodium dodecyl sulfonate was dissolved in water and, after thorough stirring and activation, was prepared into a flocculant working solution.

[0105] Iron filings were activated for 30 minutes at a ball mill speed of 600 rpm to obtain a magnetization enhancer.

[0106] The surface conditioner solution was added at 4% of the dry red mud mass fraction, and the dispersion time was 10 min.

[0107] The flocculant working solution was added at 3.5% of the dry red mud mass fraction, and the flocculation time was 25 min. In this step, to improve the flocculation effect of the flocculant, 2% of the dry red mud mass fraction of industrial diesel oil was added as a flocculant activator.

[0108] The flocculated slurry is fed into the magnetic separator feed line, and the magnetizing agent is added in four batches, with a total addition amount of 2% of the dry mass fraction of red mud, to obtain the magnetized slurry.

[0109] The magnetized slurry was subjected to magnetic separation under a magnetic field strength of 12000 Oe and a pulse frequency of 80 Hz to obtain magnetic concentrate slurry and magnetic tailings slurry. The number of magnetic separations was one.

[0110] The obtained iron concentrate had a TFe content of 65.72%, an Al2O3 content of 1.98%, and an iron recovery rate of 73.79%.

[0111] Example 5

[0112] In this embodiment, the raw material is gibbsite-type bauxite Bayer process high-iron red mud, whose main chemical components (mass percentage, wt. / %) are: Al2O3 14.56%, CaO 1.82%, SiO2 2.35%, Fe2O3 65.66%, TiO2 3.11%, Na2O 6.21%.

[0113] In this embodiment, sodium tripolyphosphate is used as the surface conditioner with an effective content of 86%; sodium oleate is used as the flocculant with an effective content of 75%; industrial diesel oil is used as the flocculant activator; and no magnetic enhancer is used.

[0114] The method is the same as in Example 1, except that:

[0115] The solid content of the pretreated slurry is 400 g / L;

[0116] Sodium silicate was dissolved in water to prepare a surface conditioner solution; sodium dodecyl sulfonate was dissolved in water and, after thorough stirring and activation, was prepared into a flocculant working solution.

[0117] Iron filings were activated for 30 minutes at a ball mill speed of 600 rpm to obtain a magnetization enhancer.

[0118] The surface conditioner solution was added at 4% of the dry red mud mass fraction, and the dispersion time was 10 min.

[0119] The amount of flocculant added to the working solution was 3.5% of the dry red mud mass fraction, and the flocculation time was 10 min.

[0120] The flocculated slurry is fed into the magnetic separator feed line, and the magnetizing agent is added in four batches, with a total addition amount of 2% of the dry mass fraction of red mud, to obtain the magnetized slurry.

[0121] The magnetized slurry was subjected to magnetic separation under a magnetic field strength of 9000 Oe and a pulse frequency of 75 Hz to obtain magnetic concentrate slurry and magnetic tailings slurry. The number of magnetic separations was one.

[0122] The obtained iron concentrate had a TFe content of 63.47%, an Al2O3 content of 2.47%, and an iron recovery rate of 66.47%.

[0123] Example 6

[0124] In this embodiment, the raw material is gibbsite-type bauxite Bayer process high-iron red mud, and its main chemical components (mass percentage, wt. / %) are: Al2O3 9.48%, CaO 1.06%, SiO2 2.78%, Fe2O3 63.66%, TiO2 2.17%, Na2O 1.81%.

[0125] In this embodiment, the surface conditioner is sodium triethylhexyl phosphate with an effective content of 80%; the flocculant is sodium dodecyl sulfate with an effective content of 88%; the flocculant activator is industrial diesel oil; and the magnetization enhancer is vanadium-titanium magnetite tailings.

[0126] The method is the same as in Example 1, except that:

[0127] The solid content of the pretreated slurry is 300 g / L;

[0128] Sodium triethylhexyl phosphate was dissolved in water to prepare a surface conditioner solution; sodium dodecyl sulfate was dissolved in water and, after thorough stirring and activation, was prepared into a flocculant working solution.

[0129] Iron filings were activated for 30 minutes at a ball mill speed of 500 rpm to obtain a magnetization enhancer.

[0130] The surface conditioner solution was added at a rate of 2.5% of the dry red mud mass fraction, and the dispersion time was 15 min.

[0131] The flocculant working solution was added at 4% of the dry red mud mass fraction, and the flocculation time was 20 min. In this step, in order to improve the flocculation effect of the flocculant, 2% of the dry red mud mass fraction of industrial diesel oil was added as a flocculant activator.

[0132] The flocculated slurry is fed into the magnetic separator feed line, and the magnetizing enhancer is added in four batches, with a total addition amount of 1% of the dry mass fraction of red mud, to obtain the magnetized slurry.

[0133] The magnetized slurry was subjected to magnetic separation under a magnetic field strength of 9500 Oe and a pulse frequency of 75 Hz to obtain magnetic concentrate slurry and magnetic tailings slurry. The number of magnetic separations was one.

[0134] The obtained iron concentrate had a TFe content of 61.78%, an Al2O3 content of 2.87%, and an iron recovery rate of 65.43%.

[0135] Example 7

[0136] In this embodiment, the raw material is gibbsite-type bauxite Bayer process high-iron red mud, whose main chemical components (mass percentage, wt. / %) are: Al2O3 18.34%, CaO 1.21%, SiO2 4.87%, Fe2O3 51.12%, TiO2 2.23%, Na2O 3.97%.

[0137] In this embodiment, sodium silicate is selected as the surface conditioner with an effective content of 85%; sodium dodecyl sulfonate is selected as the flocculant with an effective content of 76%; industrial diesel oil is selected as the active flocculant; and iron filings are selected as the magnetization enhancer.

[0138] The method is the same as in Example 1, except that:

[0139] The solid content of the pretreated slurry is 400 g / L;

[0140] Sodium silicate was dissolved in water to prepare a surface conditioner solution; sodium dodecyl sulfonate was dissolved in water and, after thorough stirring and activation, was prepared into a flocculant working solution.

[0141] Iron filings were activated for 30 minutes at a ball mill speed of 400 rpm to obtain a magnetization enhancer.

[0142] The surface conditioner solution was added at 10% of the dry red mud mass fraction, and the dispersion time was 10 min.

[0143] The amount of flocculant working solution added is 5% of the dry red mud mass fraction, and the flocculation time is 20 min. In this step, in order to improve the flocculation effect of the flocculant, 2% of the dry red mud mass fraction of industrial diesel oil is added as a flocculant activator.

[0144] The flocculated slurry is fed into the magnetic separator feed line, and the magnetizing enhancer is added in four batches, with a total addition amount of 1% of the dry mass fraction of red mud, to obtain the magnetized slurry.

[0145] The magnetized slurry was subjected to magnetic separation under a magnetic field strength of 9500 Oe and a pulse frequency of 75 Hz to obtain magnetic concentrate slurry and magnetic tailings slurry. The number of magnetic separations was one.

[0146] The obtained iron concentrate had a TFe content of 62.17%, an Al2O3 content of 3.78%, and an iron recovery rate of 60.17%.

[0147] Example 8

[0148] In this embodiment, the raw material is gibbsite-type bauxite Bayer process high-iron red mud, and its main chemical components (mass percentage, wt. / %) are: Al2O3 12.47%, CaO 12.89%, SiO2 5.28%, Fe2O3 34.49%, TiO2 4.36%, Na2O 2.98%.

[0149] In this embodiment, sodium hexametaphosphate is selected as the surface conditioner with an effective content of 80%; sodium dodecyl sulfonate is selected as the flocculant with an effective content of 75%; 200# solvent oil is selected as the flocculant activator; and iron filings are selected as the magnetization enhancer.

[0150] The solid content of the pretreated slurry is 400 g / L;

[0151] Sodium hexametaphosphate was dissolved in water to prepare a surface conditioner solution; sodium dodecyl sulfonate was dissolved in water and, after thorough stirring and activation, was prepared into a flocculant working solution.

[0152] Iron filings were activated for 60 minutes at a ball mill speed of 500 rpm to obtain a magnetization enhancer.

[0153] The surface conditioner solution was added at a rate of 0.2% of the dry red mud mass fraction, and the dispersion time was 30 min.

[0154] The amount of flocculant working solution added is 8% of the dry red mud mass fraction, and the flocculation time is 30 min. In this step, in order to improve the flocculation effect of the flocculant, 1% of the dry red mud mass fraction of 200# solvent oil is added as a flocculant activator.

[0155] The flocculated slurry is fed into the magnetic separator feed line, and the magnetizing enhancer is added in four batches, with a total addition amount of 1.2% of the dry mass fraction of red mud, to obtain the magnetized slurry.

[0156] The magnetized slurry was subjected to magnetic separation under a magnetic field strength of 18000 Oe and a pulse frequency of 10 Hz to obtain magnetic concentrate slurry and magnetic tailings slurry. The number of magnetic separations was one.

[0157] The obtained iron concentrate had a TFe content of 61.41%, an Al2O3 content of 2.87%, and an iron recovery rate of 62.01%.

[0158] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any modifications, alterations, substitutions, and variations made by those skilled in the art to the above embodiments are within the scope of the present invention.

Claims

1. A method for enhanced recovery of iron minerals from high-iron red mud, characterized in that, Includes the following steps: Step (1) Pretreatment: The Bayer process high-speed iron red mud bottom flow slurry obtained from the sedimentation process is transported to the pretreatment tank, and recycled filter water is added under mechanical stirring to dilute it and obtain the pretreated slurry. Step (2) Preparation of medicine: Dissolve the surface conditioner in water to prepare a surface conditioner solution for later use; The flocculant is dissolved in water and activated at a certain temperature with a flocculant activator to prepare a flocculant working solution for later use; The magnetization enhancer is mechanically activated to obtain a magnetization enhancer with uniform particle size for later use. Step (3) Potential control: Add a certain amount of surface conditioning agent solution from step (2) to the pretreatment slurry from step (1) to change the Zeta potential of the mineral surface, and disperse the slurry at a certain stirring speed to obtain a dispersed slurry and enhance the electrostatic repulsion between particles. Step (4) Targeted flocculation treatment: Add a certain amount of flocculant working liquid from step (2) to the dispersed slurry obtained in step (3), and carry out flocculation treatment at a certain stirring speed to obtain flocculated slurry; Step (5) Selective magnetization treatment: The flocculated slurry obtained in step (4) is transported to the magnetic separator, and the selection operation is carried out according to the quality requirements of the target iron concentrate: If high-grade iron concentrate is required, the magnetizing enhancer obtained in step (2) is added in batches during the transportation process to fully mix with the slurry to obtain the slurry to be magnetically separated; If low-grade iron concentrate is required, the flocculated slurry obtained in step (4) is directly used as the slurry to be magnetically separated. Step (6) Magnetic separation: The slurry to be magnetically separated obtained in step (5) is subjected to magnetic separation to obtain magnetic concentrate slurry and magnetic tailings slurry. The magnetic tailings slurry is returned to the pretreatment tank in step (1). Step (7) Concentration, Dehydration and Recycling: First, according to the quality requirements of the target iron concentrate, the magnetic separation concentrate slurry obtained in step (6) is concentrated to a suitable solid content by a thickener, and then dehydrated by a filter press to obtain iron concentrate and filter water; the filter water is returned to the pretreatment tank in step (1) for dilution of Bayer process high iron red mud bottom flow slurry.

2. The method for enhanced recovery of iron minerals from high-iron red mud according to claim 1, characterized in that: In step (1), the mineral type of the Bayer process high-iron red mud bottom flow slurry is either gibbsite or gibbsite, and the Fe2O3 content is not less than 30%.

3. The method for enhanced recovery of iron minerals from high-iron red mud according to claim 1, characterized in that: In step (1), the pretreatment tank is equipped with a multi-stage stirring system. The upper layer uses inclined blade turbine blades to quickly mix the slurry and reagents to achieve macroscopic homogenization. The middle layer uses folded blade or frame blades to ensure sufficient contact and surface reaction between the reagents and mineral particles. The lower layer is equipped with anchor or ribbon blades near the bottom of the tank to prevent the deposition of high-density solid particles and maintain the overall concentration stability of the tank.

4. The method for enhanced recovery of iron minerals from high-iron red mud according to claim 1, characterized in that: The solid content of the pretreated slurry in step (1) is 200~400g / L.

5. A method for enhanced recovery of iron minerals from high-iron red mud according to claim 1, characterized in that: In step (2), The surface modifier is one or more of surfactant-type, inorganic electrolyte-type, and polymer-type compounds, including one or more of sulfonates, phosphates, silicates, sulfates, polyethers, polysaccharides, and their modifiers, with an effective content ≥60% and an addition amount of 0.1%~10% of the dry mass fraction of red mud; The flocculant is one or more of carboxylates, sulfonates / sulfates, hydroxamic acid, amines, and starch compounds, with an effective content ≥75%, and the addition amount is 0.1%~10% of the dry mass fraction of red mud. The flocculant activator is a non-polar hydrocarbon oil substance, and the amount added is 0.1% to 10% of the dry mass fraction of red mud. The magnetization enhancer is an industrial iron-containing waste material, selected from one or more of magnetite tailings, steel plant sludge, or iron filings, and the amount added is 1% to 5% of the dry mass of red mud.

6. The method for enhanced recovery of iron minerals from high-iron red mud according to claim 1, characterized in that: In step (2), the mechanical activation process of the magnetizing enhancer is carried out in a high-energy planetary ball mill, the ball milling speed is controlled at 200~800 rpm, the activation time is 30~120 min, and the particle size of the obtained magnetizing enhancer meets the requirement that particles with a size ≤74μm account for more than 90% of its total mass.

7. A method for enhanced recovery of iron minerals from high-iron red mud according to claim 1, characterized in that: The stirring speed in steps (3) and (4) is 100~200 r / min, and the dispersion treatment time in step (3) and the flocculation treatment time in step (4) are 10~30 min.

8. A method for enhanced recovery of iron minerals from high-iron red mud according to claim 1, characterized in that: In step (6), the magnetic separation equipment is a wet high-intensity magnetic separator with a magnetic field strength of 5000~20000Oe, a pulse frequency of 10~80Hz, and one or more magnetic separations.

9. A method for enhanced recovery of iron minerals from high-iron red mud according to claim 1, characterized in that: In step (7), the iron concentrate has a TFe content of ≥60% and an Al2O3 content of ≤3% by mass percentage, and the iron recovery rate of a single treatment is ≥60%.

10. A method for enhanced recovery of iron minerals from high-iron red mud according to claim 1, characterized in that: In step (7), the thickener is a high-efficiency deep cone thickener and the filter press is a plate and frame filter press.

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