Desulfurization and decarburization method for high-sulfur and high-carbon bauxite

Abstract

The invention provides a desulfurization and decarbonization method for high-sulfur and high-carbon bauxite, and belongs to the field of bauxite beneficiation. The method comprises the following steps: crushing and screening the high-sulfur and high-carbon bauxite to obtain a crushed product with set granularity; the crushed product is subjected to first screening, and coarse-grained ore and undersize products are obtained; the undersize product is subjected to second screening, and medium-fraction ore and fine-fraction ore are obtained; the coarse-fraction ore is subjected to first gravity separation, and first aluminum concentrate and first tailings are obtained; the medium-grade ore is subjected to second gravity separation, and second aluminum concentrate and second tailings are obtained; the first aluminum concentrate, the second aluminum concentrate and the fine-fraction ore are combined for ore grinding, and magnetic separation fed materials are obtained; performing magnetic separation on the magnetic separation feed to obtain magnetic separation aluminum concentrate and magnetic separation tailings; and the magnetic separation aluminum concentrate is subjected to closed-loop flotation, and aluminum concentrate and sulfur concentrate are obtained. And a grading-decarburization-desulfurization mode is adopted, so that the desulfurization and decarburization effects of the high-sulfur and high-carbon bauxite are improved.

Description

Technical Field

[0001] This application relates to the field of bauxite beneficiation technology, and in particular to a desulfurization and decarbonization method for high-sulfur and high-carbon bauxite. Background Technology

[0002] In recent years, with the increasing scarcity of high-quality bauxite resources in China, the development of complex and difficult-to-process high-sulfur and high-carbon bauxite resources is conducive to ensuring the strategic security of my country's bauxite resources and empowering the sustainable development of the alumina industry. Due to the high content of sulfur and carbon, high-sulfur and high-carbon bauxite cannot be directly used for the Bayer process to produce alumina. The harm of sulfur and carbon to the Bayer process to produce alumina is mainly in the following two aspects: (1) Sulfur in bauxite is released as S2 during the leaching process of alumina production in the Bayer process. 2- S 2- SO3 2- SO4 2- The presence of different valence states of these ions seriously affects the effectiveness of the leaching process, accelerates the corrosion of production equipment, endangers equipment safety, causes pollution of the leaching solution, reduces product quality, increases alkali consumption due to reaction with alkali in the solution, is not conducive to seed decomposition, and reduces the settling ability of red mud. (2) High carbon content in bauxite will result in a high carbon-alkali ratio in alumina production, affecting leaching capacity, increasing leaching energy consumption, reducing seed decomposition rate, and affecting the particle size and quality of alumina products.

[0003] Chinese patent CN118321016A discloses an industrial production method for the comprehensive utilization of complex high-sulfur and high-carbon bauxite. This method involves crushing, grinding, and slurry conditioning the high-sulfur and high-carbon bauxite to obtain a slurry. Then, a flotation process of roughing, cleaning, and scavenging is used on the slurry with flotation reagents. Through flotation, sulfides and aluminum minerals are separated and enriched, thereby obtaining sulfur concentrate and aluminum concentrate. Using the comprehensive utilization method described in this invention, through a flotation process of "two roughing, two cleaning, and three scavenging," high-grade aluminum concentrate and sulfur concentrate products can be obtained without adding a desulfurization step. The obtained sulfur concentrate has high purity, and the obtained aluminum concentrate can be directly used in Bayer process alumina production. This method is suitable for the comprehensive utilization of complex high-sulfur and high-carbon bauxite with a sulfur content of 3-14% and a carbon content of 0.8-2%, and enables large-scale industrial production.

[0004] Chinese patent CN116213108A discloses a method for decarbonizing and removing iron from high-sulfur bauxite. The method includes: crushing the high-sulfur bauxite and screening it to a preset particle size to obtain fine-grained high-sulfur bauxite; wet coarse grinding the fine-grained high-sulfur bauxite to obtain a coarse grinding slurry; adjusting the pH of the coarse grinding slurry, and then adding flotation reagents to the slurry for flotation to obtain desulfurized aluminum concentrate; fine grinding the desulfurized aluminum concentrate and performing strong magnetic separation to obtain low-carbon, low-iron aluminum concentrate and high-carbon, high-iron tailings, respectively; the flotation reagents include inhibitors, activators, composite desulfurization collectors, and frothers; the preset particle size is 6mm to 9mm; and a "stage grinding" process is employed. The "stage separation technology combining levitation and magnetic separation" features low energy consumption, low production cost, high recovery rate, strong process adaptability, stable production, and high comprehensive utilization rate.

[0005] Chinese Patent CN118807961A discloses a desulfurization method for high-sulfur bauxite. The method includes the following steps: grinding sedimentary high-sulfur bauxite once to obtain a first feedstock; performing open-circuit flotation desulfurization on the first feedstock to obtain a first aluminum concentrate, a first sulfur concentrate, and middlings; dispersing and slurrying the middlings and then performing a second grinding to obtain a second feedstock; and performing closed-circuit flotation desulfurization on the second feedstock to obtain a second aluminum concentrate and a second sulfur concentrate. The sulfur content of the first and second aluminum concentrates obtained in this application can be as low as 0.5%, making them suitable as raw materials for alumina production. The first and second sulfur concentrates obtained can also be used as raw materials for sulfuric acid production.

[0006] Chinese patent CN114918046B discloses a desulfurization method for high-sulfur bauxite, belonging to the field of high-sulfur bauxite desulfurization technology. The method includes the following steps: obtaining high-sulfur bauxite; grinding the high-sulfur bauxite and mixing it with water to obtain a slurry; adjusting the pH of the slurry to alkaline to obtain a regulated slurry; sequentially mixing the regulated slurry with a dispersant, flocculant, collector, and frother to obtain a mixed slurry; subjecting the mixed slurry to flotation to obtain a pre-prepared alumina concentrate and a sulfur concentrate; and mixing the pre-prepared alumina concentrate with an oxidant to obtain an alumina concentrate. The obtained alumina concentrate has a sulfur content ≤0.4%, suitable for alumina production; the sulfur concentrate has a sulfur content ≥35%, suitable for sulfuric acid production, achieving comprehensive resource utilization.

[0007] Currently, the main methods for desulfurization and decarbonization of high-sulfur and high-carbon bauxite are roasting and flotation. Roasting suffers from high energy consumption and high operating costs for SO2 flue gas treatment; while flotation has poor decarbonization efficiency (especially for inorganic carbon). Furthermore, traditional sulfide mineral collectors (such as xanthates) are mostly used in flotation desulfurization, which are ineffective for high-sulfur bauxite with high sulfur content, fine particle size, and complex intergrowth relationships. Therefore, finding a new and efficient desulfurization and decarbonization method to address the problems in the desulfurization and decarbonization process of high-sulfur and high-carbon bauxite is a pressing technical challenge that needs to be solved in this field. Summary of the Invention

[0008] This application provides a desulfurization and decarbonization method for high-sulfur and high-carbon bauxite to solve the following technical problem: how to improve the desulfurization and decarbonization effect of high-sulfur and high-carbon bauxite.

[0009] This application provides a method for desulfurization and decarbonization of high-sulfur, high-carbon bauxite, the method comprising: High-sulfur, high-carbon bauxite is crushed and screened to obtain crushed products with a set particle size. The crushed product is subjected to a first screening to obtain coarse-grained ore and undersize product; The undersize product is subjected to a second screening to obtain medium-sized ore and fine-sized ore. The coarse-grained ore is subjected to a first gravity separation to obtain a first aluminum concentrate and a first tailings. The medium-sized ore is subjected to a second gravity separation to obtain a second aluminum concentrate and a second tailings. The first aluminum concentrate, the second aluminum concentrate, and the fine-grained ore are combined and ground to obtain magnetic separation feed; The magnetic feed is subjected to magnetic separation to obtain magnetically separated aluminum concentrate and magnetically separated tailings; and The magnetically separated aluminum concentrate is subjected to closed-circuit flotation to obtain aluminum concentrate and sulfur concentrate.

[0010] Optionally, the high-sulfur, high-carbon bauxite has a sulfur content of 1% to 15% and a carbon content of 1% to 5% by mass fraction.

[0011] Optionally, the particle size of the crushed product is set to -2mm to -10mm.

[0012] Optionally, the particle size threshold for the first screening is 0.15 mm to 2 mm; and / or, The particle size threshold for the second screening is 0.074 mm to 0.5 mm.

[0013] Optionally, the first gravity separation device is a heavy medium cyclone, and the medium density of the heavy medium cyclone is 1.5 g / cm³. 3 ~2.1g / cm3 The feed pressure of the heavy medium cyclone is 0.08 MPa to 0.14 MPa; and / or, The second reselection device is an interference bed separator, and the upward water flow velocity of the interference bed separator is 0.25 m / s to 0.35 m / s.

[0014] Optionally, the proportion of the magnetically separated feed particles with a size of -0.074 mm is 85% to 95%.

[0015] Optionally, the magnetic field strength of the magnetic separation is 0.7T to 1.5T; and / or, The pH value of the closed-circuit flotation is 8-10.

[0016] Optionally, the collector for flotation desulfurization is a hydrophobic nanoparticle collector, and the structural formula of the hydrophobic nanoparticle collector is shown in Formula 1:

[0017] In the formula, M is the functional monomer of the nanoparticle collector, and the structural formula of M is shown as M1, M2 and M3: .

[0018] Optionally, the contact angle of the hydrophobic nanoparticle collector is 75° to 105°, and the particle size of the hydrophobic nanoparticle collector is 65 nm to 125 nm.

[0019] Optionally, the aluminum concentrate has a carbon content of <0.3% and a sulfur content of <0.3% by mass fraction; the sulfur concentrate has a sulfur content of >40%.

[0020] The technical solutions provided in this application have the following advantages compared with the prior art: This application provides a method for desulfurization and decarbonization of high-sulfur, high-carbon bauxite. The method includes: crushing and screening the high-sulfur, high-carbon bauxite to obtain crushed products with a set particle size; performing a first screening on the crushed products to obtain coarse-grained ore and undersize product; performing a second screening on the undersize product to obtain medium-grained ore and fine-grained ore; performing a first gravity separation on the coarse-grained ore to obtain a first aluminum concentrate and a first tailings; performing a second gravity separation on the medium-grained ore to obtain a second aluminum concentrate and a second tailings; combining the first aluminum concentrate, the second aluminum concentrate, and the fine-grained ore for grinding to obtain a magnetic separation feed; performing magnetic separation on the magnetic separation feed to obtain a magnetically separated aluminum concentrate and a magnetically separated tailings; and performing closed-circuit flotation on the magnetically separated aluminum concentrate to obtain an aluminum concentrate and a sulfur concentrate. A classification-decarbonization-desulfurization method is adopted. First, high-sulfur, high-carbon bauxite is separated into three fractions: coarse, medium, and fine. Next, the coarse and medium fractions are subjected to gravity separation for decarbonization (mainly removing minerals such as dolomite and calcite). Then, the obtained coarse and medium-sized gravity-separated aluminum concentrate is combined with the fine fraction and ground for magnetic separation for decarbonization (mainly removing minerals such as goethite, hematite, and siderite). Finally, the magnetically separated aluminum concentrate is subjected to flotation desulfurization to obtain qualified aluminum and sulfur concentrates. This improves the desulfurization and decarbonization efficiency of high-sulfur, high-carbon bauxite. Attached Figure Description

[0021] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A schematic flowchart illustrating a desulfurization and decarbonization method for high-sulfur, high-carbon bauxite provided in this application embodiment; Figure 2 This is a flowchart illustrating the actual process flow of a desulfurization and decarbonization method for high-sulfur and high-carbon bauxite, as provided in this application embodiment. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0026] Furthermore, in the description of this application, the terms "comprising," "including," etc., mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple. "Parts representation" such as parts by weight or parts by mass indicates the proportional relationship between components. In the proportional relationships discussed in this article, parameters that need to be described by proportion should be understood as the first term of the proportion in the order of description, while the proportion figure should be understood as the second term. For example, if the mass ratio of substance A, substance B, and substance C is 1:2:3, then substances A, B, and C should correspond one-to-one with the proportion figure in the proportion in the order of description, i.e., the mass of substance A : the mass of substance B : the mass of substance C = 1:2:3.

[0027] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0028] The technical solution of this application embodiment is to solve the above-mentioned technical problems, and the general idea is as follows: To address the technical challenges of poor decarbonization (especially inorganic carbon) effects of flotation on high-sulfur, high-carbon bauxite, and its poor desulfurization effect on high-sulfur bauxite with high sulfur content, fine particle size, and complex intergrowth relationships, a classification-decarbonization-desulfurization method is adopted. First, the high-sulfur, high-carbon bauxite is divided into three particle sizes: coarse, medium, and fine. Second, the coarse and medium-sized particles are subjected to gravity separation for decarbonization (mainly removing minerals such as dolomite and calcite). Then, the obtained coarse and medium-sized gravity-separated aluminum concentrate is combined with the fine-sized particles, ground, and subjected to magnetic separation for decarbonization (mainly removing minerals such as goethite, hematite, and siderite). Finally, the magnetically separated aluminum concentrate is subjected to flotation desulfurization to obtain qualified aluminum and sulfur concentrates.

[0029] Figure 1 A schematic flowchart illustrating a desulfurization and decarbonization method for high-sulfur, high-carbon bauxite provided in this application embodiment; Figure 2 This is a flowchart illustrating the actual process flow of a desulfurization and decarbonization method for high-sulfur and high-carbon bauxite, as provided in this application embodiment.

[0030] like Figure 1 and Figure 2 As shown, this application provides a method for desulfurization and decarbonization of high-sulfur, high-carbon bauxite, the method comprising: S1. The high-sulfur and high-carbon bauxite is crushed and screened to obtain crushed products with a set particle size. In some embodiments, the high-sulfur, high-carbon bauxite has a sulfur content of 1% to 15% and a carbon content of 1% to 5% by mass fraction.

[0031] In some embodiments, the sulfur minerals in the high-sulfur, high-carbon bauxite have a particle size of less than 50 μm.

[0032] In some embodiments, the particle size of the crushed product is set to -2mm to -10mm.

[0033] Those skilled in the art will understand that the qualified crushed product obtained in this step has a particle size of -2 mm to -10 mm. For example, it can be any one value or any two values ​​from -2 mm, -3 mm, -4 mm, -5 mm, -6 mm, -7 mm, -8 mm, -9 mm, and -10 mm. Exceeding the threshold will not achieve a good sorting effect. At the same time, it should be noted that in the mineral processing industry, "-" is used to mean "less than" or "at most". For example, a particle size of -2 mm usually means that the maximum particle size is less than 2 mm.

[0034] Those skilled in the art will understand that this step disrupts the internal structure of the raw bauxite ore, causing it to break down from large to small. Minerals that do not meet the particle size requirements are returned to the crusher for further crushing, while those that do meet the requirements enter the next stage of grading. The particle size range of the crushed product is -2 mm to -10 mm. Reducing the product particle size is beneficial for improving the liberation degree of coarse carbonaceous minerals in the ore, making it suitable for coarse-grained product separation. However, excessively reducing the crushing particle size will increase the probability of over-grinding, affect the removal rate of carbonaceous minerals, and increase energy consumption.

[0035] S2. The crushed product is subjected to a first screening to obtain coarse-grained ore and undersize product; It should be noted that the crushed product obtained in step S1 is screened to obtain the first screen over product and the first screen under product, and the first screen over product is denoted as coarse-grained ore.

[0036] In some embodiments, the particle size threshold of the first screening is 0.15 mm to 2 mm.

[0037] Those skilled in the art will understand that the grading particle size in this step is 1.15 to 2 mm, for example, it can be any single value or any two values ​​from 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.35 mm, 1 mm, 1.5 mm, 2 mm. Exceeding the threshold will not achieve a good sorting effect.

[0038] S3. The undersize product is subjected to a second sieve to obtain medium-sized ore and fine-sized ore. It should be noted that the first undersize product obtained in step S2 is screened again to obtain the second oversize product and the second undersize product. The second oversize product is denoted as medium-grained ore, and the second undersize product is denoted as fine-grained ore.

[0039] In some embodiments, the particle size threshold of the second sieve is 0.074 mm to 0.5 mm.

[0040] Those skilled in the art will understand that the grading particle size in this step is 0.074 to 0.5 mm, for example, it can be any single value or any two values ​​from 0.074 mm, 0.1 mm, 0.125 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, and 0.5 mm. Exceeding the threshold will not achieve a good sorting effect.

[0041] S4. Perform a first gravity separation on the coarse-grained ore to obtain a first aluminum concentrate and a first tailings; In some embodiments, the first gravity separation device is a heavy medium cyclone, and the medium density of the heavy medium cyclone is 1.5 g / cm³. 3 ~2.1g / cm 3 The feed pressure of the heavy medium cyclone is 0.08 MPa to 0.14 MPa.

[0042] It should be noted that the heavy medium hydrocyclone is a high-efficiency separation device based on centrifugal force, widely used in coal and mineral processing, and especially suitable for the precise separation of fine-particle materials. The heavy medium hydrocyclone enhances material separation through centrifugal force. Its core process is as follows: The material and heavy medium suspension (such as a mixture of magnetite powder and water) enter the hydrocyclone tangentially under a certain pressure, forming a high-speed rotating vortex. Moving downwards along the inner wall of the hydrocyclone, denser particles are thrown towards the wall and discharged from the bottom outlet with the outer spiral flow. An upward spiral flow forms near the axis, causing less dense particles to gather towards the center and be discharged through the overflow outlet. The air column formed by the negative pressure of the inner spiral flow further enhances the separation accuracy and reduces particle entrainment.

[0043] Those skilled in the art will understand that the density of the heavy medium suspension is 1.5 g / cm³. 3 ~2.1 g / cm 3 For example, it could be 1.5 g / cm³ 3 1.6 g / cm 3 1.7 g / cm 3 1.8 g / cm 3 1.9 g / cm 3 2.0 g / cm 3 2.1 g / cm 3 The range of values ​​formed by any one point or any two points in the feed pressure ranges from 0.08 MPa to 0.14 MPa. For example, it can be any one point or any two points from 0.08 MPa, 0.09 MPa, 0.10 MPa, 0.11 MPa, 0.12 MPa, 0.13 MPa, and 0.14 MPa. Too low a feed pressure will lead to a decrease in sorting efficiency and poor sorting accuracy, while too high a feed pressure will lead to problems such as reversed sorting logic and decreased recovery rate.

[0044] S5. The medium-sized ore is subjected to a second gravity separation to obtain a second aluminum concentrate and a second tailings. In some embodiments, the second reselection device is an interference bed separator, wherein the upward water flow velocity of the interference bed separator is 0.25 m / s to 0.35 m / s.

[0045] It should be noted that the interfering bed separator (also known as an interfering bed separator or fluidized bed separator) is a highly efficient fine-particle material sorting device, widely used in mining, metallurgy, chemical and other fields, and particularly suitable for processing materials with micro-particle size (e.g., -0.15mm). The interfering bed separator achieves sorting based on the principle of fluidization and the interfering settling effect between particles. Its core working process is as follows: The material and the rising water (or air) flow form a fluidized bed within the separator, where particles are suspended, similar to the "boiling" phenomenon in liquids. Particles of different densities and sizes experience different resistances from the water (or air) flow in the fluidized bed, resulting in different settling velocities. High-density (or large-size) particles settle quickly, while low-density (or small-size) particles settle slowly. As the particles settle, a clear sorting interface gradually forms in the bed, with high-density particles accumulating at the bottom and low-density particles accumulating at the top. By adjusting the speed and direction of the water flow (or airflow) and setting appropriate discharge ports, high-density and low-density products can be collected separately.

[0046] Those skilled in the art will understand that the upward water flow velocity is 0.25–0.35 m / s, for example, it can be any single value or any two values ​​within the range of 0.25 m / s, 0.26 m / s, 0.27 m / s, 0.28 m / s, 0.29 m / s, 0.30 m / s, 0.31 m / s, 0.32 m / s, 0.33 m / s, 0.34 m / s, and 0.35 m / s. Exceeding the threshold will not achieve a good sorting effect.

[0047] S6. Combine the first aluminum concentrate, the second aluminum concentrate and the fine-grained ore and grind them to obtain magnetic separation feed; In some embodiments, the proportion of the magnetically separated feed particles with a size of -0.074 mm is 85% to 95%.

[0048] Those skilled in the art will understand that the proportion of particles with a size of -0.074 mm in the magnetic separation feed is 85% to 95%, for example, it can be any one value or any two values ​​from 85%, 87%, 89%, 91%, 93%, 95%, thereby ensuring that the ore particles can be fully dispersed and uniformly exposed during the magnetic separation process, thereby improving the magnetic separation efficiency and concentrate quality.

[0049] S7. Perform magnetic separation on the magnetic feed to obtain magnetically separated aluminum concentrate and magnetically separated tailings; and In some embodiments, the magnetic field strength of the magnetic separation is 0.7T to 1.5T.

[0050] As an optional implementation, the magnetic field strength is 0.7 to 1.5 T, for example, it can be any one value or any two values ​​from 0.7T, 0.8T, 0.9T, 1.0T, 1.1T, 1.2T, 1.3T, 1.4T, and 1.5T. Exceeding the threshold will not achieve a good sorting effect.

[0051] S8. The magnetically separated aluminum concentrate is subjected to closed-circuit flotation to obtain aluminum concentrate and sulfur concentrate.

[0052] In some embodiments, the pH value of the closed-circuit flotation is 8 to 10.

[0053] Those skilled in the field can understand that pH adjusters are generally sulfuric acid, hydrochloric acid, etc. pH adjusters can regulate the surface electrical properties of minerals, optimize the reaction environment of reagents, and suppress interference from harmful ions. The pH of closed-circuit flotation is 8 to 10, for example, it can be any one value or any two values ​​in the range of 8, 8.5, 9, 9.5, 10. Exceeding the threshold will not achieve a good separation effect.

[0054] In some embodiments, the collector for flotation desulfurization is a hydrophobic nanoparticle collector, the structural formula of which is shown in Formula 1:

[0055] In the formula, M is the functional monomer of the nanoparticle collector, and the structural formula of M is shown as M1, M2 and M3: .

[0056] The three functional monomers mentioned above are all azathiophene collectors. Compared with traditional desulfurization collectors, these collectors, in addition to the thiocarbonyl sulfur atom at the reaction center, also have electron-donating nitrogen, oxygen, and sulfur atoms on their heterocycles. The conjugated bonds in the molecule create conditions for electrons to flow to the coordinating atoms on the pyrite surface. Therefore, these functional monomers have a strong electron-donating ability. Furthermore, the N, O, and S atoms on the heterocycle and the S atoms outside the ring can all form coordinate bonds with the metal atoms on the pyrite surface.

[0057] In some embodiments, the contact angle of the hydrophobic nanoparticle collector is 75° to 105°, and the particle size of the hydrophobic nanoparticle collector is 65 nm to 125 nm.

[0058] In some embodiments, the aluminum concentrate has a carbon content of <0.3% and a sulfur content of <0.3% by mass fraction; the sulfur concentrate has a sulfur content of >40%.

[0059] Based on the occurrence states of carbon-containing minerals in high-sulfur and high-carbon bauxite at different particle sizes, this application adopts a three-stage decarbonization process of coarse-medium-fine particle size. The decarbonization process does not involve the addition of reagents or grinding, which can achieve green and efficient removal of carbon-containing minerals in high-sulfur bauxite and significantly reduce decarbonization costs. Meanwhile, the decarbonized alumina concentrate is desulfurized by flotation, using a self-developed hydrophobic nanoparticle collector. This collector can selectively adsorb onto the surface of fine mineral particles to improve their hydrophobicity, and can also construct hydrophobic rough micro-nano structures on the surface of mineral particles. This is beneficial for promoting the thinning and rupture of the liquid film between particles and bubbles, and strengthening the mineralization process between particles and bubbles. In addition, the added azathione-type collector functional monomer has the advantages of strong activity and strong selectivity, which can significantly improve the selectivity of the nanoparticle collector. Therefore, this nanoparticle collector has strong selectivity for sulfur-containing minerals in high-sulfur bauxite, and the desulfurization effect is significantly better than that of traditional desulfurization collectors. The resulting alumina concentrate can be used as a qualified production raw material for alumina enterprises, and the high-grade sulfur concentrate produced can be used as a raw material for sulfuric acid production.

[0060] In some implementations, flotation and refining involves more than one stage, with the middlings from each stage being returned to the next stage of the process.

[0061] In some implementations, flotation scavenging involves two or more stages, with the ore from each stage being returned to the next stage of operation.

[0062] In some implementations, the first tailings, the second tailings, and the magnetically separated tailings are combined to obtain the final mixed tailings, which can be used to produce non-fired bricks.

[0063] In summary, this application addresses the technical challenges of desulfurization and decarbonization in high-sulfur and high-carbon bauxite by proposing a combined classification-decarbonization-desulfurization process. This process integrates gravity separation, magnetic separation, and flotation technologies, and introduces novel collectors, significantly improving separation efficiency and resource utilization. It also offers advantages such as being environmentally friendly, low-cost, and promoting comprehensive resource utilization, providing an innovative solution for processing similar complex ores. The specific advantages are analyzed below: (1) Optimized classification and sorting for efficient decarbonization: The ore is divided into three grades: coarse, medium, and fine. Differentiated processes are adopted for carbon-containing minerals in different grades (such as dolomite and calcite in the coarse / medium grade, and goethite and hematite in the fine grade). The coarse / medium grade is decarbonized by gravity separation (such as heavy medium hydrocyclones), and the fine grade is decarbonized by magnetic separation to remove iron minerals, avoiding the problem of poor inorganic carbon removal by traditional flotation. At the same time, the gravity separation and magnetic separation decarbonization processes do not require the addition of chemical reagents, reducing costs and environmental pollution, and reducing the interference of impurities in the slurry before flotation, which is in line with the trend of green mineral processing.

[0064] (2) Enhanced Desulfurization with Novel Hydrophobic Nanoparticle Collector: The independently developed azathione collector (contact angle 75°~105°, particle size 65nm~125nm) significantly enhances the selective adsorption capacity for fine-grained sulfur minerals (embedded particle size <50 μm) by forming strong coordination bonds between N, O, and S atoms on the heterocycle and the pyrite surface. Simultaneously, the hydrophobic rough micro-nano structure promotes the mineralization process between bubbles and particles, improving flotation efficiency. Furthermore, compared with traditional xanthate collectors, this collector can reduce the sulfur content of aluminum concentrate to <0.3% and the sulfur content of sulfur concentrate to >40%, meeting the raw material standards for alumina production.

[0065] (3) Closed-circuit flotation process and precise parameter control: The pH value of closed-circuit flotation is controlled at 8-10. The surface electrical properties of minerals are optimized by adjusting agents such as sulfuric acid and hydrochloric acid, which suppresses the interference of harmful ions and improves the stability of flotation. At the same time, the cleaning and scavenging adopt a multi-stage middlings return design (such as cleaning stage one or more, scavenging stage two or more), which reduces the loss of useful minerals and improves the recovery rate.

[0066] (4) Energy saving and consumption reduction and comprehensive utilization of resources: The particle size of crushed products is controlled within -2 to 10 mm to avoid over-grinding (e.g., -0.074 mm accounts for 85% to 95%), thereby reducing energy consumption and improving the liberation degree of carbon minerals. Combined grinding before magnetic separation further optimizes the particle size distribution and reduces the burden of magnetic separation. At the same time, sulfur concentrate can be directly used for sulfuric acid production, and aluminum concentrate meets the needs of Bayer process alumina production, realizing the simultaneous recovery of sulfur and aluminum resources and improving the comprehensive utilization rate.

[0067] (5) Adaptable to complex ore characteristics: In view of the characteristics of fine-grained sulfur minerals (<50 μm) and complex interdistribution with aluminum minerals, the combined process of classification-magnetic separation-flotation solves the problem of poor selectivity of traditional flotation for fine sulfur particles. At the same time, it is suitable for high-sulfur and high-carbon bauxite with sulfur content of 1% to 15% and carbon content of 1% to 5%, covering the fluctuation of ore properties in different mining areas, and the process has strong stability.

[0068] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards. If there is no corresponding industry standard, then common international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0069] Example 1 First, high-sulfur, high-carbon bauxite with a carbon content of 2.48% and a sulfur content of 1.56% was crushed to a particle size of -3 mm. Then, the crushed product was graded by 0.5 mm to obtain a coarse-grained ore of +0.5-3 mm. Next, the -0.5 mm particle size was graded by 0.15 mm to obtain a medium-grained ore of +0.15-0.5 mm and a fine-grained ore of -0.15 mm. The coarse-grained ore was then subjected to heavy medium hydrocyclone separation to obtain hydrocyclone aluminum concentrate and hydrocyclone tailings, with a heavy medium density of 1.75 g / cm³. 3 The feed pressure is 0.09 MPa; the medium-sized ore is subjected to a disturbed bed separator (TBS) to obtain aluminum TBS concentrate and TBS tailings, with an upward water flow velocity of 0.28 m / s; the hydrocyclone aluminum concentrate, TBS aluminum concentrate, and fine-sized ore are then combined and ground to a particle size of -0.074 mm (90%), followed by magnetic separation at a magnetic field strength of 1.0 T to obtain magnetically separated aluminum concentrate and magnetically separated tailings; the hydrocyclone tailings, TBS tailings, and magnetically separated tailings are combined to obtain the final mixed tailings, which can be used to produce non-fired bricks; the magnetically separated aluminum concentrate is subjected to a closed-loop flotation process of "one rougher, one cleaner, and two scavengers", with a pH value of 8.5. The collector is a hydrophobic nanoparticle collector with functional monomer M1, and the collector dosage is 150 g / t (rougher) + 50 g / t (cleaner 1) + 0 g / t (scavenger 1). g / t (scavenging) yielded aluminum concentrate with a carbon content of 0.23% and a sulfur content of 0.15% with a yield of 83.86%, and sulfur concentrate with a carbon content of 8.54% and a sulfur content of 41.24% with a yield of 3.37%.

[0070] Example 2 First, high-sulfur, high-carbon bauxite with a carbon content of 1.04% and a sulfur content of 3.42% was crushed to a product size of -5 mm. Then, the crushed product was classified by 2 mm to obtain a coarse-grained ore of +2-5 mm. Next, the -2 mm fraction was classified by 0.5 mm to obtain a medium-grained ore of +0.5-2 mm and a fine-grained ore of -0.5 mm. The coarse-grained ore was then subjected to heavy medium hydrocyclone separation to obtain hydrocyclone aluminum concentrate and hydrocyclone tailings, with a heavy medium density of 1.60 g / cm³. 3The feed pressure is 0.08 MPa; the medium-sized ore is subjected to a disturbed bed separator (TBS) to obtain aluminum TBS concentrate and TBS tailings, with an upward water flow velocity of 0.35 m / s; the hydrocyclone aluminum concentrate, TBS aluminum concentrate, and fine-sized ore are then combined and ground to a -0.074 mm particle size of 90%, followed by magnetic separation at a magnetic field strength of 1.2 T to obtain magnetically separated aluminum concentrate and magnetically separated tailings; the hydrocyclone tailings, TBS tailings, and magnetically separated tailings are combined to obtain the final mixed tailings, which can be used to produce non-fired bricks; the magnetically separated aluminum concentrate is subjected to a closed-loop flotation process of "one rougher, one cleaner, and two scavengers", with a pH value of 8.5. The collector is a hydrophobic nanoparticle collector with functional monomer M3, and the collector dosage is 150 g / t (rougher) + 50 g / t (cleaner 1) + 0 g / t (cleaner 1). g / t (scavenging) yielded aluminum concentrate with a carbon content of 0.22% and a sulfur content of 0.17% with a yield of 86.32%, and sulfur concentrate with a carbon content of 5.38% and a sulfur content of 42.78% with a yield of 7.59%.

[0071] Example 3 First, high-sulfur, high-carbon bauxite with a carbon content of 1.78% and a sulfur content of 6.52% was crushed to a product size of -3 mm. Then, the crushed product was graded by 0.5 mm to obtain a coarse-grained ore of +0.5-3 mm. Next, the 0.5 mm particle size was graded by 0.074 mm to obtain a medium-grained ore of +0.074-0.5 mm and a fine-grained ore of -0.074 mm. The coarse-grained ore was then subjected to heavy medium hydrocyclone separation to obtain hydrocyclone aluminum concentrate and hydrocyclone tailings, with a heavy medium density of 1.85 g / cm³. 3 The feed pressure is 0.10 MPa; the medium-sized ore is subjected to a disturbed bed separator (TBS) to obtain aluminum TBS concentrate and TBS tailings, with an upward water flow velocity of 0.25 m / s; the hydrocyclone aluminum concentrate, TBS aluminum concentrate, and fine-sized ore are then combined and ground to a particle size of -0.074 mm (95%), followed by magnetic separation at a magnetic field strength of 1.0 T to obtain magnetically separated aluminum concentrate and magnetically separated tailings; the hydrocyclone tailings, TBS tailings, and magnetically separated tailings are combined to obtain the final mixed tailings, which can be used to produce non-fired bricks; the magnetically separated aluminum concentrate is subjected to a closed-loop flotation process of "one roughing, one cleaning, and two scavenging" with a pH of 8.5. The collector is a hydrophobic nanoparticle collector with functional monomer M2, and the collector dosage is 150 g / t (roughing) + 50 g / t (cleaning) + 0 g / t (refining). g / t (scavenging) yielded aluminum concentrate with a carbon content of 0.24% and a sulfur content of 0.19% with a yield of 78.95%, and sulfur concentrate with a carbon content of 6.13% and a sulfur content of 44.13% with a yield of 14.37%.

[0072] Example 4 First, high-sulfur, high-carbon bauxite with a carbon content of 4.56% and a sulfur content of 7.31% was crushed to a product size of -5 mm. Then, the crushed product was classified by 2 mm to obtain a coarse-grained ore of +2-5 mm. Next, the -2 mm particle size was classified by 0.5 mm to obtain a medium-grained ore of +0.5-2 mm and a fine-grained ore of -0.5 mm. The coarse-grained ore was then subjected to heavy medium hydrocyclone separation to obtain hydrocyclone aluminum concentrate and hydrocyclone tailings, with a heavy medium density of 1.65 g / cm³. 3 The feed pressure is 0.12 MPa; the medium-sized ore is subjected to a disturbed bed separator (TBS) to obtain aluminum TBS concentrate and TBS tailings, with an upward water flow velocity of 0.35 m / s; the hydrocyclone aluminum concentrate, TBS aluminum concentrate, and fine-sized ore are then combined and ground to a particle size of -0.074 mm (90%), followed by magnetic separation at a magnetic field strength of 1.2T to obtain magnetically separated aluminum concentrate and magnetically separated tailings; the hydrocyclone tailings, TBS tailings, and magnetically separated tailings are combined to obtain the final mixed tailings, which can be used to produce non-fired bricks; the magnetically separated aluminum concentrate is subjected to a closed-loop flotation process of "one rougher, one cleaner, and two scavengers", with a pH value of 8.5. The collector is a hydrophobic nanoparticle collector with functional monomer M2, and the collector dosage is 150 g / t (rougher) + 50 g / t (cleaner 1) + 0 g / t (scavenger 1). g / t (scavenging) yielded aluminum concentrate with a carbon content of 0.24% and a sulfur content of 0.20% with a yield of 70.16%, and sulfur concentrate with a carbon content of 14.34% and a sulfur content of 43.89% with a yield of 16.19%.

[0073] Example 5 First, high-sulfur, high-carbon bauxite with a carbon content of 3.62% and a sulfur content of 9.62% was crushed to a particle size of -2 mm. Then, the crushed product was graded by 0.5 mm to obtain a coarse-grained ore of +0.5-2 mm. Next, the -0.5 mm particle size was graded by 0.074 mm to obtain a medium-grained ore of +0.074-0.5 mm and a fine-grained ore of -0.074 mm. The coarse-grained ore was then subjected to heavy medium hydrocyclone separation to obtain hydrocyclone aluminum concentrate and hydrocyclone tailings, with a heavy medium density of 2.0 g / cm³. 3The feed pressure is 0.08 MPa; the medium-sized ore is separated by a disturbed bed separator (TBS) to obtain aluminum TBS concentrate and TBS tailings, with an upward water flow velocity of 0.25 m / s; the hydrocyclone aluminum concentrate, TBS aluminum concentrate, and fine-sized ore are then combined and ground to a particle size of -0.074 mm (95%), followed by magnetic separation at a magnetic field strength of 1.3T to obtain magnetically separated aluminum concentrate and magnetically separated tailings; the hydrocyclone tailings, TBS tailings, and magnetically separated tailings are combined to obtain the final mixed tailings, which can be used to produce non-fired bricks; the magnetically separated aluminum concentrate is subjected to a closed-loop flotation process of "one rougher, one cleaner, and two scavengers", with a pH value of 8.5. The collector is a hydrophobic nanoparticle collector with functional monomer M3, and the collector dosage is 150 g / t (rougher) + 50 g / t (cleaner 1) + 0 g / t (scavenger 1). g / t (scavenging) yielded aluminum concentrate with a carbon content of 0.23% and a sulfur content of 0.22% with a yield of 72.83%, and sulfur concentrate with a carbon content of 12.26% and a sulfur content of 44.17% with a yield of 21.16%.

[0074] Comparative Example 1 This comparative example adopts a method for decarbonization and iron removal of high-sulfur bauxite disclosed in Chinese patent CN202310440066.1. For high-sulfur and high-carbon bauxite with a C content of 1.74% and a S content of 2.01%, a closed-circuit flotation process of "one roughing, two cleaning, and three scavenging" is used to obtain sulfur concentrate and desulfurized aluminum concentrate. Then, the desulfurized aluminum concentrate is subjected to a magnetic separation process of one roughing (0.9T) and one scavenging (1.3T), and finally, an aluminum concentrate with a C content of 0.28% and a S content of 0.17% and a yield of 83.41% and a sulfur concentrate with a carbon content of 6.21% and a sulfur content of 36.11% and a yield of 5.11% are obtained.

[0075] Comparative Example 2 This comparative example adopts a method for decarbonization and iron removal of high-sulfur bauxite disclosed in Chinese patent CN202310440066.1. For high-sulfur and high-carbon bauxite with a C content of 1.37% and a S content of 2.41%, a closed-circuit flotation process of "one roughing, two cleaning, and three scavenging" is used to obtain sulfur concentrate and desulfurized aluminum concentrate. Then, the desulfurized aluminum concentrate is subjected to a magnetic separation process of one roughing (0.9T) and one scavenging (1.2T), and finally, an aluminum concentrate with a C content of 0.24% and a S content of 0.21% and a yield of 84.25% and a sulfur concentrate with a carbon content of 6.21% and a sulfur content of 38.72% and a yield of 5.71% are obtained.

[0076] Comparative Example 3 This comparative example adopts an industrial production method for the comprehensive utilization of complex high-sulfur and high-carbon bauxite disclosed in Chinese patent CN202410655396.7. It adopts a flotation process of "two roughing, two cleaning, and three scavenging" for high-sulfur and high-carbon bauxite with a C content of 0.95% and a S content of 7.84%, and obtains an aluminum concentrate with a C content of 0.53% and a S content of 0.25% with a yield of 79.8%, and a sulfur concentrate with a sulfur content of 36.63% and a yield of 20.20%.

[0077] The flotation parameters of Examples 1-5 and Comparative Examples 1-3 were measured, and the results are shown in Table 1.

[0078] Table 1. Flotation parameters of Examples 1-5 and Comparative Examples 1-3

[0079] In summary, Examples 1-5, employing the technical implementation scheme of this application, can all yield aluminum concentrate (carbon content < 0.3%, sulfur content < 0.3%) suitable for Bayer process alumina production and sulfur concentrate (sulfur content > 40%) suitable for sulfuric acid production. A comparison of Examples 2, 3, and 5 with Comparative Examples 1, 2, and 3 shows that, under the same carbon or sulfur content conditions, the gravity-magnetic-flotation series decarbonization and desulfurization process is superior to both magnetic-flotation and flotation-only decarbonization and desulfurization processes.

[0080] Furthermore, one or more technical solutions in the embodiments of this application have at least the following technical effects or advantages: In this embodiment of the application, in view of the shortcomings of the existing technology, namely the poor effect of flotation on decarbonization (especially inorganic carbon) of high-sulfur and high-carbon bauxite and the poor desulfurization effect on high-sulfur bauxite with high sulfur content, fine particle size and complex intercalation relationship, a method for desulfurization and decarbonization of high-sulfur and high-carbon bauxite is provided to solve the technical problem of high carbon and sulfur content in aluminum concentrate and realize the efficient utilization of high-sulfur and high-carbon bauxite.

[0081] In this embodiment, aluminum concentrate with carbon content <0.3% and sulfur content <0.3% can be obtained, which can be used for alumina production; sulfur concentrate with sulfur content >40% can be obtained, which can be used for sulfuric acid production, thus realizing the efficient and comprehensive utilization of high-sulfur and high-carbon bauxite resources.

[0082] In this embodiment, based on the occurrence states of carbon-containing minerals in high-sulfur and high-carbon bauxite at different particle sizes, a three-stage decarbonization process of coarse-medium-fine particle size is adopted. The decarbonization process does not involve the addition of reagents or grinding, which can achieve green and efficient removal of carbon-containing minerals in high-sulfur bauxite and significantly reduce decarbonization costs.

[0083] In this embodiment, the decarbonized alumina concentrate is desulfurized by flotation. The desulfurization collector used is a self-developed hydrophobic nanoparticle collector. This collector can selectively adsorb onto the surface of fine mineral particles to improve their hydrophobicity. It can also construct hydrophobic and rough micro-nano structures on the surface of mineral particles, which is beneficial to promote the thinning and rupture of the liquid film between particles and bubbles, and enhance the mineralization process between particles and bubbles. In addition, the added azathione-type collector functional monomer has the advantages of strong activity and strong selectivity, which can significantly improve the selectivity of the nanoparticle collector. Therefore, this nanoparticle collector has strong selectivity for sulfur-containing minerals in high-sulfur bauxite, and the desulfurization effect is significantly better than that of traditional desulfurization collectors.

[0084] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for desulfurization and decarbonization of high-sulfur, high-carbon bauxite, the method comprising: High-sulfur, high-carbon bauxite is crushed and screened to obtain crushed products with a set particle size. The crushed product is subjected to a first screening to obtain coarse-grained ore and undersize product; The undersize product is subjected to a second screening to obtain medium-sized ore and fine-sized ore. The coarse-grained ore is subjected to a first gravity separation to obtain a first aluminum concentrate and a first tailings. The medium-sized ore is subjected to a second gravity separation to obtain a second aluminum concentrate and a second tailings. The first aluminum concentrate, the second aluminum concentrate, and the fine-grained ore are combined and ground to obtain magnetic separation feed; The magnetic feed is subjected to magnetic separation to obtain magnetically separated aluminum concentrate and magnetically separated tailings; as well as The magnetically separated aluminum concentrate is subjected to closed-circuit flotation to obtain aluminum concentrate and sulfur concentrate.

2. The method according to claim 1, characterized in that, The high-sulfur, high-carbon bauxite has a sulfur content of 1% to 15% and a carbon content of 1% to 5% by mass fraction.

3. The method according to claim 1, characterized in that, The set particle size of the crushed product is -2mm to -10mm.

4. The method according to claim 1, characterized in that, The particle size threshold for the first screening is 0.15 mm to 2 mm; and / or, The particle size threshold for the second screening is 0.074 mm to 0.5 mm.

5. The method according to claim 1, characterized in that, The first gravity separation device is a heavy medium cyclone, and the medium density of the heavy medium cyclone is 1.5 g / cm³. 3 ~2.1g / cm 3 The feed pressure of the heavy medium cyclone is 0.08 MPa to 0.14 MPa; and / or, The second reselection device is an interference bed separator, and the upward water flow velocity of the interference bed separator is 0.25 m / s to 0.35 m / s.

6. The method according to claim 1, characterized in that, The proportion of magnetically separated feed particles with a size of -0.074 mm is 85% to 95%.

7. The method according to claim 1, characterized in that, The magnetic field strength of the magnetic separation is 0.7T to 1.5T; and / or, The pH value of the closed-circuit flotation is 8-10.

8. The method according to claim 1, characterized in that, The collector for flotation desulfurization is a hydrophobic nanoparticle collector, and the structural formula of the hydrophobic nanoparticle collector is shown in Formula 1: In the formula, M is the functional monomer of the nanoparticle collector, and the structural formula of M is shown as M1, M2 and M3: 。 9. The method according to claim 8, characterized in that, The contact angle of the hydrophobic nanoparticle collector is 75° to 105°, and the particle size of the hydrophobic nanoparticle collector is 65 nm to 125 nm.

10. The method according to claim 1, characterized in that, The aluminum concentrate has a carbon content of <0.3% and a sulfur content of <0.3% by mass fraction; the sulfur concentrate has a sulfur content of >40%.

Images