Gangue Particles Research Articles

Study on the separation mechanism of coal and gangue particles during coal slime classification in a hydrocyclone

The precise classification of coal slime containing lots of ultrafine particles provides appropriate size range of feed for subsequent sorting. In this study, experiments are performed to investigate the classification performance of coal slime. Both high-density gangue and low-density coal are considered in simulating the multi-component system of coal slime. The misplacement of fine particles in the underflow is mainly caused by −0.045 mm fine gangue component. The enrichment ratio of −0.045 mm gangue is much larger than that of −0.045 mm coal in the underflow due to its higher density. The adverse effect of particle density on classification can be reduced by increasing feed concentration appropriately. Multiphase flow pattern, theoretical force analysis, and particle trajectory are applied to reveal the migration mechanism of the coal and gangue components. This work will give insights into the migration mechanism of multi-component particles during the classification of coal slime.

Experimental Study on Confined Compaction Deformation of Crushed Gangue under Different Water Content Conditions

To study the deformation characteristics of crushed gangue under different water content conditions, the confined compaction test of crushed gangue was carried out under five different water content conditions by using a universal material testing machine and a compaction device. The strain–stress relationship in the compaction process of crushed gangue and the crushing law of gangue particles were obtained through the test, and the effects of the axial stress, water content, and relative crushing rate on the compaction deformation of crushed gangue were analyzed. The results show that the confined compaction deformation process of crushed gangue can be divided into three stages: the rapid compaction stage, crushing compaction stage, and stable compaction stage. The strain–stress relationship can be described by the parameter logarithmic function and Chapman–Richards function, respectively. The maximum change in the compression modulus under different water content states ranged from 9.9 to 19.3 MPa, and the influence of the water content on the compression modulus was more significant with increasing axial stress. There is a good correlation between particle crushing and compaction deformation. The relative crushing rate increases with the increase in the axial strain, and the increasing rate of the relative crushing rate also gradually increases. The change law of the relative crushing rate and axial strain is different in dry and water-containing conditions.

Study on Coal Gangue Identification Based on Vibration and Its Adaptability to Coal-Caving Process Parameters

The broken top coal and gangue in the fully mechanized cave mining will be released from the rear of the hydraulic support in the form of bulk. In this process, the medium properties through the coal opening can be judged by monitoring the vibration signal on the tail beam. Based on the coupling method of the discrete element method (DEM) and the finite element method (FEM) in LS-DYNA, this article simulates the whole process of coal caving, establishes the finite element model of the tail beam of hydraulic support and the discrete element model of coal gangue particles, and analyzes the influence of coal caving step distance, mining and caving ratio, and pitching angle of the mining field on the application effect of the vibration identification method. The coal caving step distance has a great influence on the recognition effect, and some bottom coal should be appropriately sacrificed to reduce the gangue content. The application effect of the vibration identification method is good under different mining and caving ratios. Downward mining can cause gangue to be released in advance, making the recognizable signal lag behind the change of gangue content, while upward mining will lose a part of the coal, but the application of vibration recognition is better than downward mining.

Simulation experimental investigations on particle breakage mechanism and fractal characteristics of mixed size gangue backfill materials

The compression deformation and particle breakage of gangue filling materials are significantly affected by different particle size gradations. To study the mechanical behavior of mixed size gangue backfilling materials in-depth, a physical compression experiment of mixed size gangue was carried out by designing a scheme based on Talbot's theory and fractal theory was used to quantify the breakage degree of mixed size gangue particles. Then, a discrete element numerical simulation was used to study the particle breakage mechanism of mixed size gangue in the compaction process. The results show that under the same vertical load, the settlement decreases monotonically with the increase in the Talbot's exponent (n), and the filling effect is significantly enhanced. The particle size distribution of mixed size gangue sample after compression has extremely good fractal characteristics. The fractal dimension has superior linear function regression relationship with n and crushing ratio. The fractal dimension decreases with increasing n. and the crushing ratio declines with increasing fractal dimension. Large-particle-size gangue is mainly broken at the initial stage of loading, while the crushing ratio of small-particle-size gangue gradually increases after the compaction stage. Large-particle-size gangue is the main bearing structure of the strong force chain, thus forming a strong skeletal structure. In the process of axial loading, cracks are mainly distributed near the “force chain skeleton”, and the contact forces around the skeleton are the first to be broken. This phenomenon causes the breakage of gangue particles, the rearrangement of particle positions and greater subsidence to fill the pores.

Freeze-thaw resistance of cement-stabilized gangue bonding materials: Effects of an ionic stabilizer

To enhance the frost resistance of cement-stabilized gangue bonding material (CSG) in road subgrade engineering, an ionic stabilizer (ICS) was added to CSG. Then, the effects of ICS on the compression resistance and freeze–thaw resistance of CSG were investigated. And the effects of ICS on the pore structure and hydration products of the CSG were analyzed by mercury intrusion porosimetry, X-ray diffraction, Fourier transform infrared spectroscopy and thermogravimetric analysis. Finally, the mechanism of action was verified by Scanning Electron Microscopy. In addition, the fractal characteristics of the pore structure of the CSG were investigated, and the pore structure characteristics and the compressive and freeze–thaw resistance properties were related. The results showed that at a short curing age, the ICS incorporation accelerated the hydration reaction rate of cement, promoted the formation of hydration products, reduced the percentage of harmful pores in the CSG, and improved the early strength and freeze–thaw resistance of the CSG. At a long curing age, the ICS incorporation increased the polymerization of silicate gel and reduced the spacing of gangue particles, which thus improved the final strength and freeze–thaw resistance of the CSG. In addition, the pore structures of the CSG under different curing ages had fractal characteristics, and t The fractal dimension provides a better and convenient demonstration of the compressive properties and freeze–thaw resistance of CSG.

Study on the Pb2+ Consolidation Mechanism of Gangue-Based Cemented Backfill

Coal mining produces a large amount of gangue that pollutes the environment, causing surface subsidence and damaging the groundwater systems. Backfill mining is an effective technology used to solve this problem, but there is a risk of polluting the groundwater due to the heavy metal ions present in the backfill material. Pb2+ has been determined to be a representative element because of its existence in coal gangue samples but not in fly ash. The risk of gangue-based cemented backfill causing groundwater pollution can be evaluated by studying the Pb2+ leaching from gangue under various conditions. When comparing the leaching amounts of Pb2+ from the coal gangue particles and the test blocks, it was found that cement filling has an obvious consolidation effect on the Pb2+ in coal gangue. The above process shows that cemented backfill has an obvious consolidation effect on the Pb2+ in gangue. The results of the theoretical analysis, X-ray, and SEM show that the consolidation mechanism can be divided into four modes: physical encapsulation, ion exchange, ion adsorption, and chemical reaction. The results are of great significance for revealing the leaching mechanism of the heavy metals in coal gangue, assessing the risk of heavy metal pollution in groundwater via gangue-cemented backfill, and improving the mining theory of the gangue-cemented filling and groundwater protection.

The shape parameters of coal and gangue particles derived from 3D scanning

The irregular shape of mineral particles directly affects the angle of repose, bulk density and flow-properties, and the interaction behaviour between the particles and a contact surface. This paper presents a dataset of spatial data and shape parameters collected from 37 gangue particles and 135 anthracite coal particles, which come from the Shangzhuang Coal Mine. The particle surface models were obtained by a Wiiboox white light raster 3D scanner and Reeyee software. To obtain the scanning surface, each particle was scanned 8 times in different axial rotation directions. The final scanning model was obtained by stacking two scanning surfaces, and the shape parameters, such as length ratio, flatness ratio, and Zingg index, were obtained. This dataset is particularly useful for researchers and engineers who want to investigate the shape of coal and gangue particles or who want to test or benchmark measurement methods concerning the three-dimensional morphology of particles.

Preparation of a novel silica-polyvinylpyrrolidone hybrid regulator and its role in ultrafine low-rank coal flotation

ABSTRACT In upgrading low-rank coal, various promoters have been employed with their fascinating abilities to alter the surface properties of particles. For decades, regulators have been proven as effective promotors in flotation. In recent years, coal flotation has benefited from the development of hybrid regulators. The interaction between coal and gangue particles can be regulated through the adjustable properties of hybrid regulators. However, when it comes to ultrafine low-rank coal (ULC), flotation becomes more difficult. The performance of micromolecule surfactants and oily collectors is not obvious when the grain size becomes finer and the coal rank becomes lower. The polymers and nanoparticles are valued for their performance. The emphasis of this study is on the preparation of silica-polyvinylpyrrolidone hybrid regulator (SiO2-PVP) and its role in low-rank coal flotation. The effect of the hybrid regulators on ULC is revealed by surface properties and chemical interactions. The contact angle, floc size, functional group, and surface topography of ULC were regulated by SiO2-PVP. The flotation response proved the benefits of SiO2-PVP to combustible recovery and clean coal. Thus, SiO2-PVP is a reliable hybrid promoter for ULC flotation. This study will be helpful to understand the effect of the polymer-nanoparticle regulator on low-rank coal flotation.

Contamination characteristics of polycyclic aromatic compounds from coal sources in typical coal mining areas in Huaibei area, China

The Huaibei area is rich in coal resources and serves as the main energy production base in East China. However, serious environmental consequences are associated with coal mining and utilization. With increasing reports on distribution and risks by polycyclic aromatic compounds (PACs), the potential pollution of coal sources must be addressed. Here, the PAC concentrations in the topsoil, coal, and coal gangue of a typical coal mining area in Huaibei were evaluated. The mean ΣPACs in topsoil, coal, and coal gangue were 1528.3, 274,815.8, and 10,908.3 μg·kg−1, respectively. Alkyl polycyclic aromatic hydrocarbons (aPAHs) were identified as primary contributors to PACs, and the concentrations of oxygenated PAHs (oPAHs) were significantly higher in coal and coal gangue than in topsoil. PAC pollution was mainly concentrated in the coal mine area and near the coal gangue landfill road. Not only sixteen high priority pollutant PAHs (16PAHs), but PAH derivatives also contributed to the organic pollution from coal sources. Principal components analysis, multiple linear regression, characteristic ratios, and positive matrix factor analysis were used to trace PAC sources. The characteristic ratios for organic pollution from coal and gangue particles involving 16PAHs, aPAHs, and oPAHs were proposed. Further, the high–ring 16PAH ratio was also found suitable for coal mining areas. The Monte–Carlo risk assessment showed that coal particles were highly carcinogenic, and despite the low carcinogenicity of coal gangue and topsoil, they might also serve as potential carcinogens. This study aimed to disseminate knowledge on PACs from coal and coal gangue, provide a useful background for efficient resource utilization of coal gangue, and a reference for tracing PAC sources in coal mine environment media.

Study on Mechanical Properties and Micro Characterization of Fibre Reinforced Ecological Cementitious Coal Gangue Materials.

Eco-gelled coal gangue materials (EGCGMs) are usually produced using coal gangue, slag, and fly ash in a highly alkaline environment. Herein, to improve the mechanical properties of such materials, polypropylene fibers were uniformly mixed with them. An unconfined compressive strength test and a three-point bending test of the fiber-reinforced EGCGMs under different conditions were conducted. Based on the performance degradation control technology of the fiber structure, the interface mechanism of the composite materials was analyzed from the micro level using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). In the mechanical test, the 28 d UCS and flexural properties of the fiber-reinforced EGCGMs were analyzed using the Box-Behnken design response surface design method and orthogonal design method, respectively. The order of significance was as follows: sodium hydroxide, fiber length, and fiber content. Within the scope of the experimental study, when the NaOH content is 3, the fiber content is 5 ‱, and the fiber length is 9 mm, the mechanical properties are the best. Based on the microscopic equipment, it was discovered that the amorphous ecological glue condensation product formed by the reaction of slag and fly ash in the alkaline environment was filled between the coal gangue particles and the fibers, and several polymerization products accumulated to form a honeycomb network topology. The distribution of fibers in the EGCGM matrix could be primarily divided into single embedded and network occurrences. The fiber inhibits the crack initiation and development of the matrix through the crack resistance effect, and improves the brittleness characteristics through the bridging effect during the failure process, which promotes the ductility of the ecological cementitious coal gangue matrix.The results presented herein can provide a theoretical basis for improving the mechanical properties of alkali-activated geopolymers.

Experimental Investigation of the Compaction-Crushing Characteristics of Graded Fractured Coal Gangue Based on Infill Mining

The compaction and re-crushing characteristics of crushed gangue are important factors which affect the quality and effectiveness of the filling of the quarry. To study the compaction and re-crushing characteristics of the gangue particles, continuous grading and intermittent grading of two different structures were designed to study the bulk gangue particle size distribution. By conducting a side-limited uniaxial compression test on the crushed gangue, the compaction deformation parameters and particle re-crushing parameters of the samples under different axial pressure and grading conditions were calculated, the interaction between compaction and re-crushing was determined, and a compaction-re-crushing model of the crushed gangue was established. The following conclusions were obtained, (1) the axial displacement increment and fractal dimension of the graded crushed gangue are closely related to the graded structure of the skeletal particles; (2) the compaction stage of the graded crushed gangue can be divided into a fast compaction stage, a slow compaction stage, and a stable compaction stage—the fast compaction stage is significantly elastic, the slow compaction stage is more plastic, and the stable stage behavior approaches that of the original rock body; (3) the degree of crushing of the graded crushed gangue increases with an increase in axial stress, and the re-crushing of the specimen mainly occurs in the slow compaction stage; (4) the compaction-crushing-fractal evolution of the graded crushed gangue in the lateral limit compression process is established as the line of questioning. The physical significance of the parameters in the equation is discussed in this paper. The study can provide theoretical support and engineering guidance for the precise filling of a quarry and the prevention of later collapse.

A degenerating convection–diffusion system modelling froth flotation with drainage

Abstract Froth flotation is a common unit operation used in mineral processing. It serves to separate valuable mineral particles from worthless gangue particles in finely ground ores. The valuable mineral particles are hydrophobic and attach to bubbles of air injected into the pulp. This creates bubble-particle aggregates that rise to the top of the flotation column where they accumulate to a froth or foam layer that is removed through a launder for further processing. At the same time, the hydrophilic gangue particles settle and are removed continuously. The drainage of liquid due to capillarity is essential for the formation of a stable froth layer. This effect is included into a previously formulated hyperbolic system of partial differential equations that models the volume fractions of floating aggregates and settling hydrophilic solids [R. Bürger, S. Diehl and M.C. Martí, IMA. J. Appl. Math. 84 (2019) 930–973]. The construction of desired steady-state solutions with a froth layer is detailed and feasibility conditions on the feed volume fractions and the volumetric flows of feed, underflow and wash water are visualized in so-called operating charts. A monotone numerical scheme is derived and employed to simulate the dynamic behaviour of a flotation column. It is also proven that, under a suitable Courant-Friedrichs-Lewy condition, the approximate volume fractions are bounded between zero and one when the initial data are.

Effects of Loading Stress and Velocity on Compression and Particle Breakage Behaviour of Waste Rocks in Backfill Coal Mining

Coal mine waste rocks, mainly broken gangue, can be used as filling materials to backfill into goafs. Under the overburden load, the backfill body is vulnerable to compressive deformation and particle breakage. With the increase in mining depth, the overlying strata will impose different loads on waste rock filling materials at different loading velocities, which further affect the material compressive deformation and particle breakage. In this paper, an experimental scheme and a loading device are designed to study the influence of loading stress and velocity on the compressive deformation and particle size distributions of the backfill materials before and after compression. The results show that the axial strain of the gangue filling materials increases rapidly with the axial stress and then gradually stabilizes, showing a logarithmic functional relationship. Increasing the loading velocity will destroy the contact structures among the gangue particles and cause a larger deformation to the filling materials. When the loading stress is relatively low (5 MPa), the gangue particles with a size larger than 20 mm have a stronger bearing capacity compared with particles of 16–20 mm, which are the first particles to be crushed under these conditions. Further increasing the loading velocity will increase the breakage degree of the filling materials. The breakage ratio (BM) has a logarithmic functional relationship with the loading stress and the loading velocity. When the ground stress is lower than 5 MPa, the content of coarse particles should be increased to enhance the bearing capacity of the gangue materials; when the ground stress is higher than 10 MPa, the content of fine particles should be increased to reduce the porosity ratio and the particle breakage ratio.

Experimental Study on Nonuniform Compaction and Re-Crushing Behavior for Crushed Coal Gangue Under Axial Loading

The crushed coal gangue particles are widely used in solid backfilling. However, the nonuniform compaction and internal re-crushing behavior of crushed coal gangue under bearing stress have not yet been revealed in current research. But this is particularly significant for improving the filling effect and quality. In this article, with the aid of the innovative compaction-acoustic emission (AE) test approach, the internal re-crushing properties of crushed coal gangue were studied. The main findings are listed; 1) the variation of AE parameters versus time is highly consistent with three stages of axial compression deformation; 2) the AE location and variation of AE intensity show that there are nonuniform compaction and layered re-crushing phenomenon in the compaction process of crushed coal gangue. The particle re-crushing transfers from the middle layer to the upper and lower layers; and 3) the particles screening results of the final compaction state show that the original particle size of the upper, middle, and lower layers account for 62%, 66%, and 76%, respectively, confirming the existence of layered crushing. The layered re-crushing characteristics of granular filling materials are revealed for the first time in this article.

Contamination characteristics and risk assessment of polycyclic aromatic compounds in soil from industrial park of Wuda District, Inner Mongolia, China

ABSTRACT Industrial Park of Wuda District is typical of industrial parks associated with coal bases in North China. Previous studies on this industrial park have focused mainly on inorganic components, such as mercury, fluorine, and water-soluble ions, with little research on polycyclic aromatic compounds (PACs). In this study, the contamination characteristics and potential health risks of alkyl polycyclic aromatic hydrocarbons (aPAHs) and 16PAHs in soil of the industrial park were examined. Under the combined influence of its own enterprises and the upwind coal fire area, the average concentration of ΣPACs was 10,176 μg·kg−1 and ranged from 177 to 42,794 μg·kg−1, exceeding the threshold for severe pollution. The average concentration of aPAHs was 7146 μg·kg−1, which was approximately twice that of the 16PAHs (3029 μg·kg−1). The parent 16PAHs were dominated by medium and high carbon rings, while the aPAHs were dominated by alkylnaphthalenes and alkylphenanthrenes. PACs were concentrated in areas of heavy polluting enterprises such as coal chemical industries and coal-fired power plants that generate point source pollution. Using the characteristic ratio method and positive matrix factorisation (PMF) analyses, it was inferred that the study area was mainly affected by petroleum sources (coal and weathered coal gangue particles) and coal fire residue, followed by wastes from coal and biomass combustion. Coal coking and transportation sources have had fewer impacts. Additionally, the toxicity levels of PACs in the soil of the industrial park exceeded regulatory thresholds. The incremental lifetime cancer risk (ILCR) was in the range of 1.0 × 10−7 to 1.7 × 10−5, indicating that the PACs in the industrial park pose a potential threat to human health. Owing to the presence of publicly accessible areas affected by coal mining, coal fire, and industrial parks in North China, the potential for widespread PAC pollution is worth consideration and investigation.

Historical Lead Smelting Slag Harmlessness and Valuable Metals Recovery: A Co-Treatment of Lead Slag and Zinc-Bearing Material in Rotary Kiln

The harmless treatment of historical lead smelting slag (LSS) is of significance to ecological and environmental protection, but it is still challenging in terms of the economic feasibility of alone processing due to the low content of valuable metals. Here, we performed an industrialized test with a co-treatment of LSS and zinc oxide ore in a rotary kiln to evaluate the economic feasibility and solidification effect of harmful elements. The results revealed that more than 70% of Zn and Pb were recovered from LSS in the form of dust, while the nonvolatile part of Pb, Zn, and Cd were solidified in gangue as complex silicate phases. The nonvolatile part of As came into being Fe-As intermetallic compound which was encapsulated by gangue particles or was solidified in silicate phases. The entirely enclosed structure of water-quenched slag plays an important role in the stability of slag. The TCLP and SNAL leaching tests demonstrated the high stability of water-quenched slag. A zinc oxide ore addition of 20% was recommended for energy consumption and processing capacity. Our findings highlight that the valuable metals not only can be effectively recovered but also harmful elements are solidified in gangue, providing an economical and feasible technical route for the treatment of historical LSS.

Experimental Investigation of Particle Size Alteration and the Selective Crushing Phenomenon of Gangue during the Jaw Crushing Process

This study examines the particle size and distribution of the main chemical components of gangue during the crushing process. Coal mine gangue was chosen as the research object, and its particle size and chemical components at various crusher discharge settings were examined through screening, grinding, chemical composition testing, and other methods. The findings demonstrate that the characteristic particle size in the gangue particle size distribution model has a logarithmic upward trend as the width of the discharge port increases. In contrast, the uniformity index has shown an exponential downward trend. The analysis of the distribution rate and enrichment ratio of the main chemical components of the gangue at different widths of the discharge port shows that the gangue exhibits obvious selective crushing during the crushing process. The distribution rate of each component is affected by the size of the screen aperture to various extents. As the discharge port width increases, the elements of CaO and MgO are enriched in the coarse-grained products, while those containing Fe2O3 are enriched from fine-grained to coarse-grained. Gangue particles containing Al2O3, SiO2, and C are enriched in the fine-grained product. In addition, by analyzing the alterations in the main chemical components of gangue at different particle size intervals, it was found that the amount of each component first rises and then falls, and the trend of enrichment ratio to particle size follows an exponential pattern. The research results have significance for guiding the selection of resource utilization methods of gangue with different particle sizes after crushing.

Microstructure and mechanical behaviors of coal gangue - Coal slime water backfill cementitious materials

Coal gangue and slime water are difficult to dispose and utilize on a large scale, which could cause environmental pollution and waste of resources. Therefore, the co-treatment of coal gangue and slime water can serve as an environmentally friendly and novel way for the collaborative resource of solid wastes. Based on this, a method for preparation of slime water-based cementitious material (SWCM) was developed, and the enhanced mechanical property of a coal gangue pile modified by SWCM (CGSWCM) was investigated. For the preparation of SWCM, 6 types of additives were selected, and solidification was achieved with a liquid to solid ratio of 3:1. A compressive strength of 0.45 MPa was acquired with raw SWCM, and the value decreased to 0.38 MPa, then increased to 0.44 MPa when the mass of the kaolin increased from 2 to 10 g. X-ray diffraction and scanning electron microscopy results showed that the pore size of the coal gangue pile decreased and the rod-like ettringite transferred to a linear shape when mass of kaolin increased. The analysis of thermogravimetry proved that the increased mass of kaolin improved the thermal stability, thus decreasing the mass loss. Therefore, it was proposed that the mechanical properties of CGSWCM was affected by evolved hydration product, gap between coal gangue particles and ettringite (AFT) morphology.

Detecting coal content in gangue via machine vision and genetic algorithm-backpropagation neural network

Coal content in gangue is one of the important technical and economic indicators of coal preparation plants and cannot be detected online at present. A novel approach based on binocular machine vision and genetic algorithm-backpropagation neural network (GA-BPNN) was proposed. First, the sample image was segmented, and each region was judged to be coal or gangue. Four size and eleven density features were extracted from each region. For the size features, the values of each feature were summed up by class, whereas the average operation was performed for the density features. The values of gangue features were divided by those of coal features to obtain an initial feature set based on a two-dimensional (2D) image. By contrast, binocular images were collected to estimate a three-dimensional (3D) feature, that is, the height features of coal and gangue particles. Subsequently, the projected area and the height feature were multiplied to obtain another 3D feature, that is, the volume feature. The Spearman correlation coefficient was adopted as the feature selection method, and eight optimal features were extracted from the final feature set, including both 2D and 3D features. Then, the coal content in gangue was modeled using a BPNN optimized by GA. Finally, three models were built based on 17 complete features, 6 optimal 2D features, and 8 optimal 3D features; another model without GA optimization was also built. The gangue sample experiment of Hongliu Coal Preparation Plant showed that the average relative error of our method was 7.98%, which is much better than that of the other three models.

Performance assessment of an innovative precise low-intensity magnetic separator

An innovative precise low-intensity magnetic separator (PLIMS) was developed for recovering low-grade magnetite. The effects of the key parameters on the separation performance of the PLIMS in recovering magnetite were investigated. The results indicated that the drum rotation speed and feed particle size played major roles in enhancing the grade of the concentrate and the recovery. Additionally, the performances of the PLIMS and selected conventional low-intensity drum magnetic separators (CLIMSs) and Davis tube testers (DTTs) were compared. The comparison revealed that the performance of the PLIMS was consistent with that of the DTT in terms of the grade of the concentrate and the recovery. In addition, the PLIMS had a higher iron grade with fewer gangue particles and higher recovery compared with the CLIMS.For the PLIMS, the remnant flux density of the magnet assembly was designed to gradually increase from low to high along the flow direction of the slurry. In the entire magnetic separation process, the magnetic force acting on the captured magnetic particles is always the most minor magnetic force required to achieve precise magnetic separation, which results in improved selectivity. Furthermore, the advantage of the PLIMS is that seven concentrates can be obtained by one magnetic separation. Therefore, the newly developed PLIMS simplifies the magnetic separation process and produces multiple products, and the grade of the concentrate can be flexibly controlled. It has a high recovery and can create various high-, medium-, and low-grade concentrates.