Beneficiation method of sulfur-containing magnetite

Abstract

The invention discloses a sulfur-containing magnetite beneficiation method which specifically comprises the following steps: S1, raw material preparation: crushing sulfur-containing magnetite to obtain small-particle sulfur-containing magnetite; s2, physicochemical property determination: detecting the particle size of the small-particle sulfur-containing magnetite, the content of magnetite in the small-particle sulfur-containing magnetite and the content of sulfur minerals in the small-particle sulfur-containing magnetite; s3, magnetic separation: according to the physicochemical properties of the small-particle sulfur-containing magnetite detected in the step S2, automatically controlling the magnetic field intensity of a magnetic separation process through a controller, and carrying out magnetic separation to obtain magnetite and sulfur-containing ore; the magnetic field intensity of the magnetic separation process is dynamically adjusted according to the iron ore particle size of the sulfur-containing magnetite, the magnetite content in the sulfur-containing magnetite and the sulfur mineral content, the trends of iron minerals and sulfur minerals are accurately controlled, optimal adjustment of the element trends is achieved, and the recovery rate of iron and sulfur is increased.

Description

Technical Field

[0001] This invention relates to the field of mineral processing techniques, and in particular to a beneficiation method for sulfur-containing magnetite. Background Technology

[0002] Sulfur-bearing magnetite is an important source of iron and sulfur minerals in my country. Its mineral composition is complex, with the main iron minerals including magnetite, pyrite, marcasite, and pyrrhotite. Traditional beneficiation processes typically use magnetic separation as a pretreatment step, separating waste rock after crushing and screening the ore into different particle sizes using a magnetic separator. However, in actual production, the complex interaction between ore particle size, magnetite content, sulfur mineral content, and magnetic field strength leads to two prominent problems during magnetic separation: first, some sulfur minerals remain in the iron concentrate, affecting its quality; second, some iron minerals are lost with the tailings, resulting in resource waste. This incomplete separation directly necessitates additional desulfurization and iron removal processes in subsequent steps, increasing production costs and reducing overall process efficiency.

[0003] Existing technologies for processing sulfur-containing magnetite mainly include magnetic separation, flotation, and roasting.

[0004] (1) Magnetic separation

[0005] Magnetic separation in mineral processing plants separates valuable minerals from gangue minerals based on their magnetic differences. The strength of a mineral's magnetic properties is measured by its specific magnetic susceptibility. The greater the difference in specific magnetic susceptibility between minerals, the better the separation effect of magnetic separation. The Ganzhou Nonferrous Metallurgical Research Institute, addressing the high sulfur and phosphorus content in the Meishan iron ore concentrate, employed magnetic separation to treat the flotation-desulfurized iron concentrate, yielding an iron concentrate with an iron grade of 56.08% and a sulfur content of 0.29%. Compared to the original ore, the iron grade increased by 3.81%, the sulfur content decreased by 0.15%, and the iron recovery rate reached 94.51%.

[0006] Pyrite and magnetite have significantly different specific magnetic susceptibility, allowing them to be separated effectively through magnetic separation. However, pyrrhotite and magnetite have similar specific magnetic susceptibility and are both strongly magnetic minerals, making separation through magnetic separation generally difficult. During magnetic separation, pyrrhotite inevitably enters the iron concentrate, leading to a decrease in concentrate quality. Therefore, conventional magnetic separation desulfurization methods are suitable only for desulfurizing magnetite that does not contain pyrrhotite.

[0007] (2) Flotation

[0008] Magnetite and pyrrhotite are both strongly magnetic minerals, and magnetic separation often fails to achieve effective separation between them. Pyrrhotite is characterized by its fragility, tendency to become muddy, and ease of oxidation, making it an easily suppressed and difficult-to-float iron sulfide mineral. Currently, flotation is the most commonly used separation method. Therefore, flotation is an effective and frequently used method for iron ore desulfurization. Extensive research has been conducted both domestically and internationally on the separation mechanism of pyrrhotite and magnetite, yielding certain results. Moslemi H and Shamsi P et al. studied the potentials of pyrite and pyrrhotite. Their research showed that as pH increases, the potentials of pyrrhotite and pyrite reverse, thus decreasing the floatability of these two minerals at high pH values. As pH decreases, the potential difference between pyrrhotite and pyrite and the steel electrode increases, which is more conducive to the separation of these two minerals. Allison A et al. studied the mechanism of copper sulfate activation of pyrrhotite. This research indicates that pyrrhotite, like most sulfide minerals, requires a certain degree of oxidation to fully react with xanthate. Adding sulfuric acid does not allow pyrrhotite to react with xanthate under insufficient oxidation conditions, but adding copper sulfate can accelerate the reaction between xanthate and pyrrhotite. Research by Hu Yuehua, Dai Jingping, and others shows that using DDTC as a collector, the floatability of pyrrhotite is good within a pH range of 2-12, but the recovery rate drops rapidly above pH 12. During flotation, diethyldithiocarbamic acid reacts with pyrrhotite to produce tetraethyldisulfide, making the pyrrhotite surface hydrophobic and thus causing it to float. Iron ore flotation desulfurization mainly employs the acidic-sulfide ore collector reverse flotation method. This process uses sulfuric acid as a pH adjuster to adjust the pulp pH to around 5, adding adjusters, sulfide ore collectors, and frothers. By floating the sulfides in the ore, desulfurization is achieved. This process is currently the main method used for iron ore flotation desulfurization in China.

[0009] (3) Roasting

[0010] Sulfur in iron ore generally exists in the form of sulfides. It can be removed by volatile oxidation roasting, where the metal sulfides are oxidized at high temperatures to form SO2. Meishan Iron Mine began simple production in 1970, collecting rich ore, crushing and screening it, and then sending it to the Meishan sintering plant where it is mixed with imported ore and roasted for desulfurization. Roasting can remove 95% of the sulfur from the ore. Although there is no iron loss during roasting desulfurization, and it can be carried out together with sintering, saving costs, a large amount of sulfur is released into the atmosphere as SO2 during the roasting process, seriously polluting the atmosphere and harming crops.

[0011] (4) Leaching

[0012] Leaching is a commonly used process in chemical mineral processing. It can be used to remove sulfur from pyrite slag. Currently, most of the sulfuric acid produced in my country comes from pyrite roasting, generating tens of millions of tons of acid-producing waste slag annually, causing significant pollution and waste. This waste slag typically contains 30-60% iron, along with impurities such as silicon, sulfur, and phosphorus, making it unsuitable for direct use in ironmaking processes. Xie Haiquan et al. studied pyrite slag with an iron content of 58% and a sulfur content of 0.7% provided by a phosphate fertilizer plant. Using a method of leaching the pyrite slag with dilute sulfuric acid solution, they ultimately obtained a qualified iron concentrate with an iron content of 62% and a sulfur content of 0.2%.

[0013] Therefore, for sulfur-bearing magnetite, existing beneficiation processes are difficult to guarantee efficient separation of magnetite and sulfur minerals, and it is also difficult to guarantee the iron grade and sulfur content of magnetite. Summary of the Invention

[0014] The purpose of this invention is to address the shortcomings of existing sulfur-containing magnetite beneficiation processes, where some sulfur remains in the iron concentrate and some iron is lost in the tailings due to the waste disposal process during magnetic separation. This invention proposes a beneficiation method for sulfur-containing magnetite, which dynamically adjusts the magnetic field strength of the magnetic separation process based on the iron ore particle size, magnetite content, and sulfur mineral content in the sulfur-containing magnetite, precisely controlling the orientation of iron and sulfur minerals, optimizing the element orientation, and improving the recovery rate of iron and sulfur.

[0015] The specific solution of this invention is: a beneficiation method for sulfur-containing magnetite, which specifically includes the following steps:

[0016] S1. Raw material preparation: The sulfur-containing magnetite is crushed to obtain small-particle sulfur-containing magnetite.

[0017] S2. Physicochemical property determination: Detect the particle size of small-particle sulfur-containing magnetite, the content of magnetite in small-particle sulfur-containing magnetite, and the content of sulfur minerals in small-particle sulfur-containing magnetite;

[0018] S3. Magnetic Separation: Based on the physicochemical properties of the small-particle sulfur-containing magnetite detected in step S2, the magnetic field strength of the magnetic separation process is automatically controlled by the controller to carry out magnetic separation and obtain magnetite and sulfur-containing ore. The adjustment of the magnetic field strength is based on a preset algorithm that substitutes the detection data into the magnetic field strength calculation formula to adjust the working parameters of the magnetic separator. During the magnetic separation process, different magnetic minerals produce different movement trajectories in the gradient magnetic field. Magnetite is captured in the magnetite area due to its strong magnetism, while sulfur minerals are discharged with the tailings due to their weak magnetism. This process forms a closed-loop control through parameter feedback to ensure that the magnetic field strength is always optimally matched with the ore characteristics.

[0019] The calculation of the magnetic field strength for controlling the magnetic separation process in step S3 is specifically as follows:

[0020] In the formula: H is the magnetic field strength of the magnetic separation process; K is the magnetic field strength adjustment coefficient of the magnetic separation process, with a value of 500 to 5000; S is the percentage of sulfur mineral content in small-particle sulfur-containing magnetite; M is the percentage of magnetite content in small-particle sulfur-containing magnetite; a is the magnetite content adjustment coefficient, with a value of 0.01 to 0.5; D is the average particle size of small-particle sulfur-containing magnetite, mm; b is the average particle size adjustment index of the magnetic separation waste disposal process, with a value of 0.2 to 1.0.

[0021] Furthermore, the magnetic field strength adjustment coefficient K mentioned in this invention is specifically achieved by adjusting the working current or the number of coil turns of the magnetic separator, with a value range of 500 to 5000, used to match the magnetic separation requirements of different ore types; the sulfur mineral content S refers to the mass percentage of sulfur ore in sulfur-containing magnetite, specifically detected by X-ray fluorescence spectroscopy or chemical titration; the magnetite content M refers to the mass percentage of magnetite in the ore, specifically detected by a magnetic material content analyzer or chemical phase analysis; the magnetite content adjustment coefficient a refers to the proportional factor for adjusting the magnetic field strength according to the magnetite content, with a value range of 0.01 to 0.5; the average particle size D refers to the geometric mean size of the ore particles, specifically determined by a laser particle size analyzer or sieving method; the particle size adjustment index b refers to the nonlinear coefficient of the influence of particle size on magnetic field strength, with a value range of 0.2 to 1.0.

[0022] Furthermore, step S1 in this invention specifically involves: crushing and screening the sulfur-containing magnetite to obtain small-particle sulfur-containing magnetite with a particle size of less than 60 mm.

[0023] Furthermore, in step S2 of this invention, the particle size of the small-particle sulfur-containing magnetite is detected by particle size sieving; the content of magnetite in the small-particle sulfur-containing magnetite is detected by iron chemical phase detection; and the content of sulfur minerals in the small-particle sulfur-containing magnetite is detected by sulfur mineral content detection.

[0024] Furthermore, the magnetite obtained in step S3 of this invention is further processed through any one of magnetic separation, flotation, or roasting to obtain magnetite concentrate; the obtained sulfur-containing ore is further processed through a leaching process to obtain sulfuric acid and acid production waste residue; the acid production waste residue is mixed into the sulfur-containing magnetite raw material for cyclic beneficiation.

[0025] Furthermore, in step S3 of this invention, adjusting the operating parameters of the magnetic separator is specifically achieved by adjusting the operating current or the number of coil turns of the magnetic separator.

[0026] To address the technical problem of this invention, the inventors discovered a strong correlation between pyrophosphate separation efficiency and the physicochemical properties of the ore. Through systematic research on the influence of ore particle size distribution, the proportion of magnetic minerals, and sulfide content on the magnetic separation process, they found that dynamically adjusting the magnetic field strength can effectively improve separation accuracy. Based on this, they proposed a method to achieve precise adaptation of magnetic separation process parameters by real-time monitoring of ore physicochemical parameters and establishing a magnetic field strength control model, thereby overcoming the limitations of traditional fixed magnetic field strength models.

[0027] This application proposes a mineral processing method that includes raw material crushing, physicochemical property testing, and magnetic field strength control. The method first crushes sulfur-containing magnetite into small particles, then measures the particle size, magnetite content, and sulfur mineral content. Finally, based on the test data, the magnetic field strength of the magnetic separator is dynamically adjusted to achieve selective separation of pyrite minerals.

[0028] Crushing refers to reducing the ore size through mechanical force, specifically achieved using jaw crushers and cone crushers for staged crushing, resulting in particles smaller than 80 mm. Physicochemical property determination includes particle size analysis, quantitative analysis of magnetic minerals, and sulfur content detection, specifically achieved using laser particle size analyzers, magnetic susceptibility meters, and X-ray fluorescence spectrometers. Magnetic field strength control involves establishing a mathematical model based on ore particle size, magnetite content, and sulfur content parameters to dynamically calculate the optimal magnetic field strength value, specifically achieved through an electromagnetic coil current adjustment device. In this invention, after sulfur-containing magnetite undergoes multi-stage crushing to form uniform particles, the particle size distribution, magnetite percentage, and sulfur mineral content data are obtained through a detection system. Based on a preset algorithm, the detection data are substituted into the magnetic field strength calculation formula to adjust the magnetic separator's operating parameters. During magnetic separation, different magnetic minerals exhibit differentiated trajectories in the gradient magnetic field. Magnetite, due to its strong magnetism, is captured in the magnetite zone, while sulfur minerals, due to their weak magnetism, are discharged with the tailings. This process forms a closed-loop control through parameter feedback, ensuring that the magnetic field strength always maintains an optimal match with the ore characteristics.

[0029] Compared to existing technologies, traditional magnetic separation processes employ a fixed magnetic field strength mode, which cannot adapt to fluctuations in ore properties. This method solves the problem of magnetic separation efficiency fluctuations caused by differences in ore particle size by establishing a dynamic correlation model between magnetic field strength and ore parameters, overcoming the negative impacts of sulfur content, magnetite content, and mineral particle size variations on separation accuracy. Compared to the mixing of pyrrhotite and magnetite in conventional processes, this method achieves effective separation of the two through precise control of the magnetic field strength.

[0030] Through the technical solution of this invention, the sulfur residue rate in iron concentrate and the iron loss rate in tailings are effectively reduced, thereby improving the separation accuracy of pyrite. The closed-loop control mechanism of this method can adaptively process sulfur-containing magnetite ores with different properties, reducing the workload of subsequent desulfurization and iron removal processes, and providing a reliable solution for the efficient separation of complex-component pyrite.

[0031] Compared to existing technologies, conventional magnetic separation processes typically employ fixed magnetic field strength or adjust the magnetic field based on only a single parameter, making it difficult to address the synergistic effects of sulfur content, magnetite content, and particle size. This invention addresses this by establishing a multi-parameter coupled magnetic field strength calculation model, achieving a comprehensive response to ore characteristics. For example, in traditional methods for processing pyrrhotite-containing ores, the lack of consideration for the impact of sulfur minerals on magnetic separation efficiency easily leads to excessive sulfur content in the iron concentrate. This invention, by introducing a sulfur mineral content parameter, allows for targeted adjustment of the magnetic field strength to suppress the magnetic separation and recovery of sulfur minerals.

[0032] Through the above technical solution, this application can dynamically optimize the magnetic field strength based on the sulfur content, magnetite content, and particle size characteristics of the ore, effectively reducing the entrainment rate of sulfur minerals in magnetite and minimizing the loss of iron minerals in tailings. For example, when processing ores with fluctuating sulfur content, the automatic adjustment of the magnetic field strength can maintain the magnetite recovery rate within the process requirements, avoiding fluctuations in concentrate quality caused by interference from sulfur minerals. Furthermore, the introduction of a particle size adjustment index allows the magnetic field strength to adapt to the separation needs of ores with different particle size distributions, improving the waste disposal efficiency of coarse ore and the recovery accuracy of fine ore.

[0033] Through the technical solution of this invention, this application can avoid the problem of incomplete magnetic separation caused by excessively large ore particle size, reduce the residue of sulfur minerals in magnetite and the loss of magnetite in tailings. By limiting the particle size range after crushing and screening, a uniform material basis is provided for subsequent magnetic separation processes, thereby improving the selective adsorption efficiency of the magnetic field on the target mineral.

[0034] This application further proposes step S2, which involves detecting the particle size of small-particle sulfur-containing magnetite using a particle size analysis method. The particle size analysis method refers to classifying and screening particulate materials using a standard sieve to determine their particle size distribution. Specifically, this can be achieved using a multi-layer vibrating screen or rotary screen with sieves of different aperture sizes. After each stage of screening, the mass of particles remaining on each sieve layer is weighed, and the average particle size is calculated. This screening process directly reflects the actual physical size of the particles, providing fundamental parameters for adjusting the magnetic field strength in subsequent magnetic separation processes, ensuring that the magnetic field waste removal process matches the material particle size. Specifically, after the raw material crushing process is completed, the obtained small-particle sulfur-containing magnetite sample is placed in a screening device and classified and screened according to the preset sieve specifications. During the screening process, particles larger than the sieve aperture size are retained on the sieve, while particles smaller than the sieve aperture size pass through the sieve to the next layer. By recording the particle mass percentage of each sieve layer and combining it with the sieve aperture size data, the average particle size of the material can be calculated. This data, along with the sulfur mineral content and magnetite content, is input into the magnetic field strength calculation formula to dynamically adjust the operating parameters of the magnetic separator, thereby optimizing the magnetic separation efficiency.

[0035] This application further proposes a step S2 method for detecting the magnetite content in small-particle sulfur-bearing magnetite using a chemical phase detection method. This method utilizes the selective solubility characteristics of different chemical reagents for the occurrence of iron, determining the magnetite content through stepwise dissolution and quantitative analysis. Specifically, acidic solutions such as hydrochloric acid, sulfuric acid, or nitric acid can be used to leach the sample in stages, and the iron content in the solution can be determined by combining atomic absorption spectroscopy or inductively coupled plasma atomic emission spectroscopy, thereby distinguishing the ratio of magnetite to other iron-bearing minerals. This method achieves mineral phase separation through the difference in chemical dissolution, avoiding interference from the mineral embedding morphology during physical separation. Specifically, in the beneficiation process of sulfur-bearing magnetite, the magnetite content directly affects the magnetic field strength setting of the magnetic separation process. The chemical phase detection method can accurately distinguish the occurrence state of iron in magnetite from other sulfur-bearing iron minerals such as pyrrhotite and ferrite. For example, under acidic conditions, pyrrhotite preferentially dissolves while magnetite remains stable. By controlling the dissolution conditions and measuring the iron content in stages, the proportion of magnetite can be quantitatively calculated. This detection result provides accurate input parameters for subsequent magnetic field strength calculations, ensuring that the magnetic separation process effectively separates the target minerals.

[0036] This application further proposes a method for detecting the content of sulfur minerals in small-particle sulfur-bearing magnetite using a sulfur mineral content detection method in step S2. This method refers to the quantitative analysis of the form and proportion of sulfur in minerals using chemical or physical means. Specifically, it can be achieved by combining X-ray diffraction analysis with chemical phase analysis. By identifying the crystal structure characteristics and elemental composition of sulfur minerals, different sulfide types such as pyrite and pyrrhotite can be distinguished and their mass fractions calculated. This detection method can accurately quantify the actual content of sulfur minerals, providing data support for the dynamic adjustment of subsequent magnetic separation process parameters. Specifically, in the implementation of the sulfur mineral content detection method, the crushed sulfur-bearing magnetite sample is first ground and prepared. Then, an X-ray diffractometer is used to scan the sample to determine the types and relative proportions of sulfur minerals through characteristic peak matching. The total sulfur content is further determined by chemical titration or inductively coupled plasma atomic emission spectrometry, and the actual content of each sulfur mineral is calculated based on the phase analysis results. This detection process can accurately obtain the content distribution data of different sulfur minerals such as pyrite and pyrrhotite, providing key input parameters for the magnetic field strength calculation model.

[0037] This application further proposes processing the magnetite obtained through magnetic separation into magnetite concentrate through any one of the following steps: magnetic separation, flotation, or roasting. After initial magnetic separation, based on the sulfur residue and iron grade in the magnetite concentrate, a secondary magnetic separation can be used to enhance the enrichment of magnetic minerals, or flotation can be used to preferentially remove sulfides coated on the surface of magnetite particles, or sulfur minerals can be completely decomposed in a high-temperature roasting process. For example, when the sulfur content in the magnetite concentrate is high and the sulfur exists in the form of pyrrhotite, flotation can be used preferentially. By adjusting the pH of the pulp to the acidic range and adding xanthate collectors, pyrrhotite and magnetite can be selectively separated. This forms a multi-process synergistic graded processing mechanism, effectively solving the problem that a single magnetic separation process is insufficient to completely separate magnetite and sulfur minerals.

[0038] This application further proposes processing the sulfur-containing ore obtained in step S3 through a leaching process to obtain sulfuric acid and acid production waste residue. The leaching process refers to the selective dissolution of sulfur in sulfur minerals using chemical solvents. Specifically, this can be achieved by soaking the sulfur-containing ore in a dilute sulfuric acid solution, which induces a chemical reaction in the sulfur minerals to generate soluble sulfates through an acidic environment. Sulfuric acid is the product formed after concentrating and purifying the sulfur-containing compound solution generated during the leaching reaction. It can be obtained by separating it from the leachate through an evaporation crystallization process. The acid production waste residue refers to the solid material remaining after the leaching reaction, mainly containing unreacted iron minerals and silicate impurities. It can be separated from the solid residue through a solid-liquid separation process. Specifically, the leaching process involves mixing the sulfur-containing ore with an acidic solution and reacting it under specific temperature conditions, converting the sulfur in the sulfur minerals into soluble sulfates that enter the liquid phase. After the reaction, the leachate and solid residue are separated by filtration or centrifugation. The leachate can be concentrated by evaporation to obtain sulfuric acid. The solid residue has a high iron mineral content and can be returned to the mineral processing flow for recycling. This process achieves efficient sulfur extraction through chemical dissolution, avoiding the gas pollution problems caused by high-temperature roasting. In some specific embodiments, the acidic solution can be a 5%-30% sulfuric acid solution, and the reaction temperature can be controlled within the range of 50-90℃. The leaching reaction time can be dynamically adjusted according to the sulfur mineral content; for example, when the sulfur content is high, the reaction time can be extended to 2-4 hours. After dehydration and drying, the acid production waste residue can be mixed with newly added sulfur-containing magnetite raw material and re-entered into the crushing and screening process for mineral processing.

[0039] This application further proposes mixing acid production waste residue into sulfur-containing magnetite raw materials for cyclic beneficiation. The acid production waste residue refers to the solid waste generated during the roasting of pyrite to produce acid, containing iron, sulfur, and silicon-phosphorus impurities. Specifically, it can be the residue from the roasting of pyrite in the sulfuric acid production process. This waste residue has a high iron content but excessive impurities, making it unsuitable for direct iron smelting. Circular beneficiation refers to re-inputting the acid production waste residue as raw material into the beneficiation process. Specifically, this can be achieved by crushing and screening it, then mixing it with the original sulfur-containing magnetite and entering a magnetic separation process. Through further separation, residual iron and sulfur minerals can be extracted from the waste residue. Specifically, the acid production waste residue, after crushing and screening, is mixed with the original sulfur-containing magnetite raw material in a certain proportion and then enters the magnetic separation waste disposal process. Under the control of a magnetic field strength adjustment formula, the magnetite and sulfur minerals in the waste residue are separated and recovered. Waste residue that is not separated can be returned to the process for recycling. This process reduces waste residue accumulation and lowers raw material consumption by reusing valuable components in the waste residue.

[0040] In this invention, the formula is obtained by the inventor based on experimental and engineering applications. All calculations are numerical values ​​converted according to the specified units. The converted values ​​are substituted into the formula for calculation (after converting the units, only the numerical values ​​are substituted into the formula for calculation, not the units; the units are only used to adjust the size of the numerical values).

[0041] The technical solution provided by this invention allows for precise control of the magnetic field strength during the magnetic separation process based on the particle size, magnetite content, and sulfur mineral content of small-particle sulfur-containing magnetite. This effectively ensures the iron grade of the magnetite and avoids obtaining magnetite with excessively high sulfur content. At the same time, it prevents excessive iron from entering the sulfur-containing ore, thereby avoiding resource waste.

[0042] Compared with the prior art, the technical solution provided by the present invention has the following beneficial technical effects:

[0043] The present invention provides a beneficiation method for sulfur-containing magnetite, which effectively solves the problems of sulfur mineral residue and iron mineral loss in traditional magnetic separation processes by detecting ore particle size, magnetite and sulfur mineral content, and dynamically adjusting the magnetic field strength based on a formula. It has the advantages of improving the separation efficiency of magnetite and sulfur minerals, reducing resource waste and production costs. Detailed Implementation

[0044] This invention relates to a beneficiation method for sulfur-containing magnetite, specifically comprising the following steps:

[0045] S1. Raw material preparation: The sulfur-containing magnetite is crushed to obtain small-particle sulfur-containing magnetite; Specifically, step S1 in this invention is: the sulfur-containing magnetite is crushed and screened to obtain small-particle sulfur-containing magnetite with a particle size of less than 60mm.

[0046] S2. Physicochemical property determination: The particle size, magnetite content, and sulfur mineral content of the small-particle sulfur-containing magnetite are determined. Further, in step S2 of this invention, the particle size of the small-particle sulfur-containing magnetite is determined by particle size analysis; the magnetite content is determined by iron chemical phase analysis; and the sulfur mineral content is determined by sulfur mineral content analysis.

[0047] S3. Magnetic Separation: Based on the physicochemical properties of the small-particle sulfur-containing magnetite detected in step S2, the magnetic field strength of the magnetic separation process is automatically controlled by the controller to perform magnetic separation, obtaining magnetite and sulfur-containing ore. The adjustment of the magnetic field strength is based on a preset algorithm, which substitutes the detection data into the magnetic field strength calculation formula to adjust the working parameters of the magnetic separator. During the magnetic separation process, different magnetic minerals produce differentiated movement trajectories in the gradient magnetic field. Magnetite, due to its strong magnetism, is captured in the magnetite area, while sulfur minerals, due to their weak magnetism, are discharged with the tailings. This process forms a closed-loop control through parameter feedback to ensure that the magnetic field strength is always optimally matched with the ore characteristics. Furthermore, the magnetite obtained in step S3 of this invention is further processed through any one of the following processes: magnetic separation, flotation, or roasting, to obtain magnetite concentrate. The obtained sulfur-containing ore is further processed through a leaching process to obtain sulfuric acid and acid production waste residue. The acid production waste residue is mixed into the sulfur-containing magnetite raw material for cyclic beneficiation. Furthermore, the adjustment of the working parameters of the magnetic separator in step S3 of this invention is specifically achieved by adjusting the working current or the number of coil turns of the magnetic separator.

[0048] The calculation of the magnetic field strength for controlling the magnetic separation process in step S3 is specifically as follows:

[0049]

[0050] In the formula: H is the magnetic field strength of the magnetic separation process; K is the magnetic field strength adjustment coefficient of the magnetic separation process, with a value of 500 to 5000; S is the percentage of sulfur mineral content in small-particle sulfur-containing magnetite; M is the percentage of magnetite content in small-particle sulfur-containing magnetite; a is the magnetite content adjustment coefficient, with a value of 0.01 to 0.5; D is the average particle size of small-particle sulfur-containing magnetite, mm; b is the average particle size adjustment index of the magnetic separation waste disposal process, with a value of 0.2 to 1.0.

[0051] Furthermore, the magnetic field strength adjustment coefficient K mentioned in this invention is specifically achieved by adjusting the working current or the number of coil turns of the magnetic separator, with a value range of 500 to 5000, used to match the magnetic separation requirements of different ore types; the sulfur mineral content S refers to the mass percentage of sulfur ore in sulfur-containing magnetite, specifically detected by X-ray fluorescence spectroscopy or chemical titration; the magnetite content M refers to the mass percentage of magnetite in the ore, specifically detected by a magnetic material content analyzer or chemical phase analysis; the magnetite content adjustment coefficient a refers to the proportional factor for adjusting the magnetic field strength according to the magnetite content, with a value range of 0.01 to 0.5; the average particle size D refers to the geometric mean size of the ore particles, specifically determined by a laser particle size analyzer or sieving method; the particle size adjustment index b refers to the nonlinear coefficient of the influence of particle size on magnetic field strength, with a value range of 0.2 to 1.0.

[0052] To address the technical problem of this invention, the inventors discovered a strong correlation between pyrophosphate separation efficiency and the physicochemical properties of the ore. Through systematic research on the influence of ore particle size distribution, the proportion of magnetic minerals, and sulfide content on the magnetic separation process, they found that dynamically adjusting the magnetic field strength can effectively improve separation accuracy. Based on this, they proposed a method to achieve precise adaptation of magnetic separation process parameters by real-time monitoring of ore physicochemical parameters and establishing a magnetic field strength control model, thereby overcoming the limitations of traditional fixed magnetic field strength models.

[0053] This application proposes a mineral processing method that includes raw material crushing, physicochemical property testing, and magnetic field strength control. The method first crushes sulfur-containing magnetite into small particles, then measures the particle size, magnetite content, and sulfur mineral content. Finally, based on the test data, the magnetic field strength of the magnetic separator is dynamically adjusted to achieve selective separation of pyrite minerals.

[0054] Crushing refers to reducing the ore size through mechanical force, specifically achieved using jaw crushers and cone crushers for staged crushing, resulting in particles smaller than 80 mm. Physicochemical property determination includes particle size analysis, quantitative analysis of magnetic minerals, and sulfur content detection, specifically achieved using laser particle size analyzers, magnetic susceptibility meters, and X-ray fluorescence spectrometers. Magnetic field strength control involves establishing a mathematical model based on ore particle size, magnetite content, and sulfur content parameters to dynamically calculate the optimal magnetic field strength value, specifically achieved through an electromagnetic coil current adjustment device. In this invention, after sulfur-containing magnetite undergoes multi-stage crushing to form uniform particles, the particle size distribution, magnetite percentage, and sulfur mineral content data are obtained through a detection system. Based on a preset algorithm, the detection data are substituted into the magnetic field strength calculation formula to adjust the magnetic separator's operating parameters. During magnetic separation, different magnetic minerals exhibit differentiated trajectories in the gradient magnetic field. Magnetite, due to its strong magnetism, is captured in the magnetite zone, while sulfur minerals, due to their weak magnetism, are discharged with the tailings. This process forms a closed-loop control through parameter feedback, ensuring that the magnetic field strength always maintains an optimal match with the ore characteristics.

[0055] Compared to existing technologies, traditional magnetic separation processes employ a fixed magnetic field strength mode, which cannot adapt to fluctuations in ore properties. This method solves the problem of magnetic separation efficiency fluctuations caused by differences in ore particle size by establishing a dynamic correlation model between magnetic field strength and ore parameters, overcoming the negative impacts of sulfur content, magnetite content, and mineral particle size variations on separation accuracy. Compared to the mixing of pyrrhotite and magnetite in conventional processes, this method achieves effective separation of the two through precise control of the magnetic field strength.

[0056] Through the technical solution of this invention, the sulfur residue rate in iron concentrate and the iron loss rate in tailings are effectively reduced, thereby improving the separation accuracy of pyrite. The closed-loop control mechanism of this method can adaptively process sulfur-containing magnetite ores with different properties, reducing the workload of subsequent desulfurization and iron removal processes, and providing a reliable solution for the efficient separation of complex-component pyrite.

[0057] Compared to existing technologies, conventional magnetic separation processes typically employ fixed magnetic field strength or adjust the magnetic field based on only a single parameter, making it difficult to address the synergistic effects of sulfur content, magnetite content, and particle size. This invention addresses this by establishing a multi-parameter coupled magnetic field strength calculation model, achieving a comprehensive response to ore characteristics. For example, in traditional methods for processing pyrrhotite-containing ores, the lack of consideration for the impact of sulfur minerals on magnetic separation efficiency easily leads to excessive sulfur content in the iron concentrate. This invention, by introducing a sulfur mineral content parameter, allows for targeted adjustment of the magnetic field strength to suppress the magnetic separation and recovery of sulfur minerals.

[0058] Through the above technical solution, this application can dynamically optimize the magnetic field strength based on the sulfur content, magnetite content, and particle size characteristics of the ore, effectively reducing the entrainment rate of sulfur minerals in magnetite and minimizing the loss of iron minerals in tailings. For example, when processing ores with fluctuating sulfur content, the automatic adjustment of the magnetic field strength can maintain the magnetite recovery rate within the process requirements, avoiding fluctuations in concentrate quality caused by interference from sulfur minerals. Furthermore, the introduction of a particle size adjustment index allows the magnetic field strength to adapt to the separation needs of ores with different particle size distributions, improving the waste disposal efficiency of coarse ore and the recovery accuracy of fine ore.

[0059] Through the technical solution of this invention, this application can avoid the problem of incomplete magnetic separation caused by excessively large ore particle size, reduce the residue of sulfur minerals in magnetite and the loss of magnetite in tailings. By limiting the particle size range after crushing and screening, a uniform material basis is provided for subsequent magnetic separation processes, thereby improving the selective adsorption efficiency of the magnetic field on the target mineral.

[0060] This application further proposes step S2, which involves detecting the particle size of small-particle sulfur-containing magnetite using a particle size analysis method. The particle size analysis method refers to classifying and screening particulate materials using a standard sieve to determine their particle size distribution. Specifically, this can be achieved using a multi-layer vibrating screen or rotary screen with sieves of different aperture sizes. After each stage of screening, the mass of particles remaining on each sieve layer is weighed, and the average particle size is calculated. This screening process directly reflects the actual physical size of the particles, providing fundamental parameters for adjusting the magnetic field strength in subsequent magnetic separation processes, ensuring that the magnetic field waste removal process matches the material particle size. Specifically, after the raw material crushing process is completed, the obtained small-particle sulfur-containing magnetite sample is placed in a screening device and classified and screened according to the preset sieve specifications. During the screening process, particles larger than the sieve aperture size are retained on the sieve, while particles smaller than the sieve aperture size pass through the sieve to the next layer. By recording the particle mass percentage of each sieve layer and combining it with the sieve aperture size data, the average particle size of the material can be calculated. This data, along with the sulfur mineral content and magnetite content, is input into the magnetic field strength calculation formula to dynamically adjust the operating parameters of the magnetic separator, thereby optimizing the magnetic separation efficiency.

[0061] This application further proposes a step S2 method for detecting the magnetite content in small-particle sulfur-bearing magnetite using a chemical phase detection method. This method utilizes the selective solubility characteristics of different chemical reagents for the occurrence of iron, determining the magnetite content through stepwise dissolution and quantitative analysis. Specifically, acidic solutions such as hydrochloric acid, sulfuric acid, or nitric acid can be used to leach the sample in stages, and the iron content in the solution can be determined by combining atomic absorption spectroscopy or inductively coupled plasma atomic emission spectroscopy, thereby distinguishing the ratio of magnetite to other iron-bearing minerals. This method achieves mineral phase separation through the difference in chemical dissolution, avoiding interference from the mineral embedding morphology during physical separation. Specifically, in the beneficiation process of sulfur-bearing magnetite, the magnetite content directly affects the magnetic field strength setting of the magnetic separation process. The chemical phase detection method can accurately distinguish the occurrence state of iron in magnetite from other sulfur-bearing iron minerals such as pyrrhotite and ferrite. For example, under acidic conditions, pyrrhotite preferentially dissolves while magnetite remains stable. By controlling the dissolution conditions and measuring the iron content in stages, the proportion of magnetite can be quantitatively calculated. This detection result provides accurate input parameters for subsequent magnetic field strength calculations, ensuring that the magnetic separation process effectively separates the target minerals.

[0062] This application further proposes a method for detecting the content of sulfur minerals in small-particle sulfur-bearing magnetite using a sulfur mineral content detection method in step S2. This method refers to the quantitative analysis of the form and proportion of sulfur in minerals using chemical or physical means. Specifically, it can be achieved by combining X-ray diffraction analysis with chemical phase analysis. By identifying the crystal structure characteristics and elemental composition of sulfur minerals, different sulfide types such as pyrite and pyrrhotite can be distinguished and their mass fractions calculated. This detection method can accurately quantify the actual content of sulfur minerals, providing data support for the dynamic adjustment of subsequent magnetic separation process parameters. Specifically, in the implementation of the sulfur mineral content detection method, the crushed sulfur-bearing magnetite sample is first ground and prepared. Then, an X-ray diffractometer is used to scan the sample to determine the types and relative proportions of sulfur minerals through characteristic peak matching. The total sulfur content is further determined by chemical titration or inductively coupled plasma atomic emission spectrometry, and the actual content of each sulfur mineral is calculated based on the phase analysis results. This detection process can accurately obtain the content distribution data of different sulfur minerals such as pyrite and pyrrhotite, providing key input parameters for the magnetic field strength calculation model.

[0063] This application further proposes processing the magnetite obtained through magnetic separation into magnetite concentrate through any one of the following steps: magnetic separation, flotation, or roasting. After initial magnetic separation, based on the sulfur residue and iron grade in the magnetite concentrate, a secondary magnetic separation can be used to enhance the enrichment of magnetic minerals, or flotation can be used to preferentially remove sulfides coated on the surface of magnetite particles, or sulfur minerals can be completely decomposed in a high-temperature roasting process. For example, when the sulfur content in the magnetite concentrate is high and the sulfur exists in the form of pyrrhotite, flotation can be used preferentially. By adjusting the pH of the pulp to the acidic range and adding xanthate collectors, pyrrhotite and magnetite can be selectively separated. This forms a multi-process synergistic graded processing mechanism, effectively solving the problem that a single magnetic separation process is insufficient to completely separate magnetite and sulfur minerals.

[0064] This application further proposes processing the sulfur-containing ore obtained in step S3 through a leaching process to obtain sulfuric acid and acid production waste residue. The leaching process refers to the selective dissolution of sulfur in sulfur minerals using chemical solvents. Specifically, this can be achieved by soaking the sulfur-containing ore in a dilute sulfuric acid solution, which induces a chemical reaction in the sulfur minerals to generate soluble sulfates through an acidic environment. Sulfuric acid is the product formed after concentrating and purifying the sulfur-containing compound solution generated during the leaching reaction. It can be obtained by separating it from the leachate through an evaporation crystallization process. The acid production waste residue refers to the solid material remaining after the leaching reaction, mainly containing unreacted iron minerals and silicate impurities. It can be separated from the solid residue through a solid-liquid separation process. Specifically, the leaching process involves mixing the sulfur-containing ore with an acidic solution and reacting it under specific temperature conditions, converting the sulfur in the sulfur minerals into soluble sulfates that enter the liquid phase. After the reaction, the leachate and solid residue are separated by filtration or centrifugation. The leachate can be concentrated by evaporation to obtain sulfuric acid. The solid residue has a high iron mineral content and can be returned to the mineral processing flow for recycling. This process achieves efficient sulfur extraction through chemical dissolution, avoiding the gas pollution problems caused by high-temperature roasting. In some specific embodiments, the acidic solution can be a 5%-30% sulfuric acid solution, and the reaction temperature can be controlled within the range of 50-90℃. The leaching reaction time can be dynamically adjusted according to the sulfur mineral content; for example, when the sulfur content is high, the reaction time can be extended to 2-4 hours. After dehydration and drying, the acid production waste residue can be mixed with newly added sulfur-containing magnetite raw material and re-entered into the crushing and screening process for mineral processing.

[0065] This application further proposes mixing acid production waste residue into sulfur-containing magnetite raw materials for cyclic beneficiation. The acid production waste residue refers to the solid waste generated during the roasting of pyrite to produce acid, containing iron, sulfur, and silicon-phosphorus impurities. Specifically, it can be the residue from the roasting of pyrite in the sulfuric acid production process. This waste residue has a high iron content but excessive impurities, making it unsuitable for direct iron smelting. Circular beneficiation refers to re-inputting the acid production waste residue as raw material into the beneficiation process. Specifically, this can be achieved by crushing and screening it, then mixing it with the original sulfur-containing magnetite and entering a magnetic separation process. Through further separation, residual iron and sulfur minerals can be extracted from the waste residue. Specifically, the acid production waste residue, after crushing and screening, is mixed with the original sulfur-containing magnetite raw material in a certain proportion and then enters the magnetic separation waste disposal process. Under the control of a magnetic field strength adjustment formula, the magnetite and sulfur minerals in the waste residue are separated and recovered. Waste residue that is not separated can be returned to the process for recycling. This process reduces waste residue accumulation and lowers raw material consumption by reusing valuable components in the waste residue.

[0066] In this invention, the formula is obtained by the inventor based on experimental and engineering applications. All calculations are numerical values ​​converted according to the specified units. The converted values ​​are substituted into the formula for calculation (after converting the units, only the numerical values ​​are substituted into the formula for calculation, not the units; the units are only used to adjust the size of the numerical values).

[0067] The technical solution provided by this invention allows for precise control of the magnetic field strength during the magnetic separation process based on the particle size, magnetite content, and sulfur mineral content of small-particle sulfur-containing magnetite. This effectively ensures the iron grade of the magnetite and avoids obtaining magnetite with excessively high sulfur content. At the same time, it prevents excessive iron from entering the sulfur-containing ore, thereby avoiding resource waste.

[0068] The application of the method of the present invention will be explained in detail below.

[0069] Specifically, the steps are as follows:

[0070] S1. Raw material preparation: The sulfur-containing magnetite is crushed to obtain small-particle sulfur-containing magnetite; specifically, the sulfur-containing magnetite is crushed and screened to obtain small-particle sulfur-containing magnetite with an average particle size of less than 60mm.

[0071] S2. Physicochemical Property Determination: This involves determining the particle size, magnetite content, and sulfur mineral content of small-particle sulfur-containing magnetite. In step S2, the particle size of the small-particle sulfur-containing magnetite is determined by particle size analysis. In step S2, the magnetite content in the small-particle sulfur-containing magnetite is determined by iron chemical phase analysis. In step S2, the sulfur mineral content in the small-particle sulfur-containing magnetite is determined by sulfur mineral content analysis.

[0072] S3. Magnetic Separation: Based on the physicochemical properties of the small-particle sulfur-containing magnetite obtained in step S2, the magnetic field strength of the magnetic separation process is controlled to perform magnetic separation, obtaining magnetite and sulfur-containing ore. The specific formula for calculating the magnetic field strength for controlling the magnetic separation process is as follows:

[0073]

[0074] In the formula: H is the magnetic field strength of the magnetic separation process, GS; K is the magnetic field strength adjustment coefficient of the magnetic separation process, with a value of 2000; S is the sulfur mineral content in small-particle sulfur-containing magnetite, %; M is the magnetite content in small-particle sulfur-containing magnetite, %; a is the magnetite content adjustment coefficient, with a value of 0.1; D is the average particle size of small-particle sulfur-containing magnetite, mm; b is the average particle size adjustment index of the magnetic separation waste disposal process, with a value of 0.5.

[0075] The magnetite obtained in step S3 is further processed through any one of the following steps: magnetic separation, flotation, or roasting, to obtain magnetite concentrate. The sulfur-containing ore obtained in step S3 is further processed through a leaching process to obtain sulfuric acid and acid production waste residue. The acid production waste residue is mixed into the sulfur-containing magnetite raw material for recycling.

[0076] The following section will use the processing of a specific sulfur-bearing magnetite as an example to illustrate this further.

[0077] After crushing, the average particle size of the small sulfur-containing magnetite particles obtained is 40mm.

[0078] Physicochemical property determination: The content of magnetite in small-particle sulfur-containing magnetite is 75%; the content of sulfur minerals in small-particle sulfur-containing magnetite is 19%.

[0079] Based on the physicochemical properties of the small-particle sulfur-containing magnetite, the magnetic field strength H for the magnetic separation process is calculated (where K is taken as 2000; a as 0.1; b as 0.5):

[0080] The magnetic field strength was controlled at 1740 GS during the magnetic separation process to obtain magnetite and sulfur-bearing ore. Analysis showed that the iron grade of the magnetite was 68.2% and the sulfur content was 0.11%; the iron content of the sulfur-bearing ore was 7.5%.

Claims

1. A method for beneficiating sulfur-containing magnetite, characterized in that, Specifically, it includes the following steps: S1. Raw material preparation: The sulfur-containing magnetite is crushed to obtain small-particle sulfur-containing magnetite. S2. Physicochemical property determination: Detect the particle size of small-particle sulfur-containing magnetite, the content of magnetite in small-particle sulfur-containing magnetite, and the content of sulfur minerals in small-particle sulfur-containing magnetite; S3. Magnetic Separation: Based on the physicochemical properties of the small-particle sulfur-containing magnetite detected in step S2, the magnetic field strength of the magnetic separation process is automatically controlled by the controller to carry out magnetic separation and obtain magnetite and sulfur-containing ore. The adjustment of the magnetic field strength is based on a preset algorithm that substitutes the detection data into the magnetic field strength calculation formula to adjust the working parameters of the magnetic separator. During the magnetic separation process, different magnetic minerals produce different movement trajectories in the gradient magnetic field. Magnetite is captured in the magnetite area due to its strong magnetism, while sulfur minerals are discharged with the tailings due to their weak magnetism. This process forms a closed-loop control through parameter feedback to ensure that the magnetic field strength is always optimally matched with the ore characteristics. The calculation of the magnetic field strength for controlling the magnetic separation process in step S3 is specifically as follows: In the formula: H is the magnetic field strength of the magnetic separation process; K is the magnetic field strength adjustment coefficient of the magnetic separation process, with a value of 500 to 5000; S is the percentage of sulfur mineral content in small-particle sulfur-containing magnetite; M is the percentage of magnetite content in small-particle sulfur-containing magnetite; a is the magnetite content adjustment coefficient, with a value of 0.01 to 0.5; D is the average particle size of small-particle sulfur-containing magnetite, mm; b is the average particle size adjustment index of the magnetic separation waste disposal process, with a value of 0.2 to 1.

0.

2. The beneficiation method for sulfur-bearing magnetite according to claim 1, characterized in that, The magnetic field strength adjustment coefficient K is specifically achieved by adjusting the working current or the number of coil turns of the magnetic separator, with a value ranging from 500 to 5000, used to match the magnetic separation requirements of different ore types; the sulfur mineral content S refers to the mass percentage of sulfur ore in sulfur-containing magnetite, specifically detected by X-ray fluorescence spectroscopy or chemical titration; the magnetite content M refers to the mass percentage of magnetite in the ore, specifically detected by a magnetic material content analyzer or chemical phase analysis; the magnetite content adjustment coefficient a is a proportional factor for adjusting the magnetic field strength according to the magnetite content, with a value ranging from 0.01 to 0.5; the average particle size D refers to the geometric mean size of the ore particles, specifically determined by a laser particle size analyzer or sieving method; the particle size adjustment index b is a nonlinear coefficient of the influence of particle size on magnetic field strength, with a value ranging from 0.2 to 1.

0.

3. The beneficiation method for sulfur-bearing magnetite according to claim 1, characterized in that, Step S1 specifically involves: crushing and screening sulfur-containing magnetite to obtain small-particle sulfur-containing magnetite with a particle size of less than 60 mm.

4. The beneficiation method for sulfur-bearing magnetite according to claim 1, characterized in that, In step S2, the particle size of small-particle sulfur-containing magnetite is detected by particle size sieving; the content of magnetite in small-particle sulfur-containing magnetite is detected by iron chemical phase detection; and the content of sulfur minerals in small-particle sulfur-containing magnetite is detected by sulfur mineral content detection.

5. The beneficiation method for sulfur-bearing magnetite according to claim 1, characterized in that, The magnetite obtained in step S3 is further processed through any one of the following processes: magnetic separation, flotation, or roasting, to obtain magnetite concentrate; the obtained sulfur-containing ore is further processed through a leaching process to obtain sulfuric acid and acid production waste residue; the acid production waste residue is mixed into the sulfur-containing magnetite raw material for cyclic beneficiation.

6. The beneficiation method for sulfur-bearing magnetite according to claim 1, characterized in that, In step S3, adjusting the operating parameters of the magnetic separator is specifically achieved by adjusting the operating current or the number of coil turns of the magnetic separator.

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