Dry Separation Research Articles

Removing Iron Impurities from Feldspar Ore Using Dry Magnetic Separation (Part One)

Removing Iron Impurities from Feldspar Ore Using Dry Magnetic Separation (Part One)

APPLICATION OF A GAS-SOLID FLUIDISED BED SEPARATOR FOR ALUMINIUM-COPPER SCRAP RECYCLING

The EUbs circular economy concept necessitates the recycling of material streams used once or multiple times into the productionb consumption cycle again and again. The commonly known problem b that the number of recycling cycles of plastics is limited drives the economy towards metal usage again, because metal recycling cycles are limitless. Therefore, the efficient and economic separation of mixed aluminium and copper scraps in the 30b100 mm particle size range is an important issue for our society. In this study fundamental and applied research was carried out for the application of a gas-solid fluidised bed separator for aluminium-copper scrap recycling. A laboratory scale aero-suspension dense media separator was developed. Fundamental fluidisation experiments were carried out with this device and a powder rheometer. Afterwards pilot-scale and later industrial-scale separators were designed and built. The results indicate that the well-known Ergun fluidisation model can be the basis of a new process engineering design method for sizing dry fluidised bed separators.

3D strongly anisotropic intrinsic thermal conductivity of polypropylene separator

In this work, the thermal conductivity in every direction is reported for the first time for the dry separator component made out of polypropylene (PP) that is used in lithium-ion batteries. Herein, a PP separator film is studied dry and in vacuum, as an example of polyolefins separators. These separators are crucial for performance parameters, including cycle life, thermal management, energy and power density, and safety. Hence, a better understanding of the thermal conductivity k in different in-plane directions (parallel and normal direction to the stretching direction in fabrication) as well as the out-of-plane direction is crucial to the overall performance. k of dry PP separator, measured in vacuum, is found four times bigger in the parallel direction (0.217 W⋅m−1⋅K−1) than that in the normal direction (0.043 W⋅m−1⋅K−1), all for the in-plane direction. This strong anisotropy can be explained by the macroscopic and microscopic anisotropic structure and intrinsic anisotropic thermal conductivity of aligned PP. Moreover, the out-of-plane k of the dry PP separator is measured to be 0.036 and 0.025 W⋅m−1⋅K−1 in the air and vacuum, respectively, suggesting good parallel structure of PP in the thickness direction.

Demonstration of dry magnetic separation to upgrade the Mn:Fe ratio of a ferromanganese ore sample

ABSTRACT Sighter Induced Roll Magnetic Separation tests were conducted on a ferromanganese ore sample to determine the potential to significantly upgrade the Mn content and Mn:Fe ratio. The sample had a Mn:Fe ratio of 1.3 and was comprised of hematite, cryptomelane, pyrolusite, quartz, goethite and braunite. Tests at 4.7, 2.3 and 1 mm top sizes revealed better separation of Fe from Mn at the 2.3 and 1 mm top sizes. This reflected the better liberation and separation characteristics of Fe oxides at 2.3 mm and both Fe and Mn oxides at 1 mm. A test on the −2.3 + 0.6 mm size fraction improved the Mn:Fe ratio to 4.6, the Mn content to 41.5 wt% with 69.4% mass recovery and 84.2% Mn recovery. Particle magnetic susceptibility was influenced by particle microporosity, and its effect on apparent density, resulting in some Mn oxides reporting to the magnetic concentrate and Fe oxides to the tails.

Influence of air velocity and powder bed height on local density and float–sink of spheres in a gas–solid fluidized bed

Depending on their density, large objects will either float or sink in a gas–solid fluidized bed due to the liquid–like properties and density of the fluidized bed. The float–sink technology has been applied to dry density separations in industry. It is important for optimized industrial application to understand how the air velocity and the powder bed height affect the float–sink as the key operating factors. In this study, we investigated the float–sink of spheres of various density by varying the air velocity and the powder bed height. Also, we obtained the local fluidized bed density and the buoyancy force working on the sphere at various heights. We used the weight of a stainless-steel sphere in the fluidized bed to estimate the local fluidized bed density and the buoyancy force based on Archimedes principle. We found that the spheres float–sink behavior changes dramatically with the air velocity and the powder bed height and that the spheres float–sink behavior is correlated to ΔF = Fb – Fg, where Fb is the buoyancy force and Fg is the gravity force acting on the sphere. We also found that the fluidized bed density is not constant as a function of height when the air velocity is relatively large; the local fluidized bed density is interestingly either minimal at approximately mid-height or surprisingly, gradually increases with height within the fluidized bed at higher air velocities. The possible reasons are discussed by considering the local variation of the motion of air bubbles and the fluidized medium which affect the fluid force acting on the sphere in the fluidized bed.

Relation between storm characteristics and extreme precipitation statistics over CONUS

In this paper we use a statistical framework to analyze the relation between storm properties and the statistics of extreme precipitation. We identify storm events using a 24-hour dry hiatus separation. We investigate the statistics of the hourly maximum intensity for the heaviest storm events at durations of 1 and 24 h. A two-parameter Weibull distribution is used to represent precipitation frequencies at several stations from a quality-controlled hourly precipitation dataset over the contiguous United States, encompassing seven climate zones. The Spearman correlation between the distribution parameters and a selection of storm properties (duration, intensity, decorrelation time, convective-like ratio) and station properties (elevation and latitude) is used to measure the relation of these properties with the statistics of extreme precipitation. Our results indicate that observed annual maximum hourly precipitation over the entire study area are likely samples from the used distribution, implying that a two-parameter Weibull distribution is suitable for modeling hourly and 24-hour precipitation extremes over the contiguous United States. The spatial variability of shape parameters obtained for hourly events showed lighter tails in the west coast when compared to the rest of CONUS, while the central-north displays heavier tails. We identify statistically significant links (at the 95% confidence level) between storm characteristics connected with the underlying processes (e.g., typical storm duration, typical temporal autocorrelation, proportion of convective-like storms) and the parameters of the distribution. Notably, characteristics typical of convective precipitation, e.g., sharp decorrelation time and high hourly intensity, tend to be related to distributions with heavier tails. These results provide a first step towards linking the characteristics of storms with the local statistics of extremes.

Effect of multi parameter synergy on the upgrading characteristics of wide size moist coal

ABSTRACT Through composite dry separation, effective precipitation and impurity removal can be achieved, improving the quality of raw coal. This paper mainly systematically analyzes the synergistic control mechanisms of airflow velocity, airflow transition layer height and control angle on the upgrading characteristics of moist coal. The results show that Zone I is a high airflow area, and when v = 2.12 m/s, it can effectively destroy the original static stable structure of low-density particles, increase the degree of freedom of particle accumulation volume, and achieve effective precipitation of particles. Zone II is a medium air volume area, and when v = 1.78 m/s, the high-density particle group in this area has the weakest obstruction effect on airflow, which can achieve efficient particle precipitation. Zone III is a low airflow area, where the dispersion of high-density particle groups increases at v = 1.36 m/s. The airflow can effectively act on the particles through the bed layer, reducing their surface water. When the height (H) of the gas transition layer is 49-52 mm and the regulatory perspective is 20–25, the distribution uniformity of the gas flow in the bed is the best. After separation and upgrading, the moist coal concentrate yield is 78.3%, ash content is 10.05%, as well as the possible deviation E value is 0.1 g/cm3.

A preliminary investigation of dry gravity separation with low specific gravity ores using a laboratory Knelson Concentrator

It has become an active research area for treating low specific gravity (SG) deposits by centrifugal separation due to its high efficiency, low cost and minor environmental impact. Laboratory Knelson Concentrator has shown its potential for processing high density ores on a dry basis. This study investigated the feasibility and the optimum operating conditions when processing a dry low SG feed with a modified Knelson Concentrator. A synthetic mixture of magnetite and quartz with a grade of 1% magnetite was used to mimic a low-density ratio ore. Bowl speed (G), air fluidizing pressure (psi) and solids feed rate (g/min) were chosen as the operating variables. Box-Behnken design was used to design the experiments and response surface method was used for optimization. The effects of each individual factors and their interactions on concentrate grade and magnetite recovery were evaluated. The dry process achieved up to 60 % magnetite recovery with an upgrade ratio of 5. The optimized values for the concentration with the highest recovery and grade of bowl speed, solids feed rate and air fluidizing pressure are 27 G, 200 g/min and 12 psi, respectively.

DEMİR ÇELİK TESİS ATIKLARININ GERİ DÖNÜŞÜMÜ

As a result of the processes applied in the steel production, approximately 400 kg of waste is generated for every one ton of steel products. According to environmental regulations, these wastes must be disposed or stored in waste dams, which imposes a serious financial burden on iron and steel enterprises. In recent years, wastes with a high iron content has been recovered and returned to the steelmaking processes, replacing ore and contributing to a more efficient use of resources. However, despite the high iron content, it is not possible to use high sulphur content wastes as raw material in steel production. In this study, it is aimed to increase the utilization possibilities of these wastes as secondary raw material by reducing the content of sulphur in the concentrate by magnetic separation. It was shown that 33.34% of the wastes can be recycled with 54.90% iron recovery and 74.43% sulphur removal after dry magnetic separation experiments while 14.66% of the wastes can be recycled with 28.60% iron recovery and 89.93% sulphur removal after wet magnetic separation experiments. These removals correspond to 0.03% and 0.01% sulphur contents in the concentrates after dry and wet magnetic separations, respectively, and the concentrates can be blended back into the main raw material.

Dry Magnetic Separation of Ash from a Coal Power Station

The purpose was to expand the applicaation area of dry ash in power plants. It was shown that using ash with a low content of Fe2O3 (~7%) allows to obtain a high-iron concentrate with a Fe2O3 content of 70%. The Fe2O3 extraction from ash is dependent on the magnetic induction and fractional ash composition. The conclusion was made about the possibility of using the obtained magnetite concentrate in ferrous metallurgy in the manufacture of basic iron and steel.

Towards dry fractionation of soybean meal into protein and dietary fiber concentrates

Tribo-electrostatic separation of hexane-defatted soybean flour was studied to produce protein- and fiber-rich fractions. The separation was carried out under laminar and turbulent airflow rates and plate voltages ranging from ±1 to ±6.5 kV. The combination of laminar airflow rate and high plate voltage resulted in the highest yield of protein and fiber particles with modest enrichment levels. Accordingly, the soybean flour was enriched in protein from 55.3 to 58.4% and fiber from 15.4 to 19.6%, accounting for 44.4 and 16.8% protein and fiber separation efficiencies, respectively. The distribution of protein and fiber along the negatively charged electrode showed no significant difference in terms of enrichment level. Still, more protein and fiber particles accumulated at the bottom of the electrode, according to the yield results. At 7 LPM and ±6.5 kV, a direct relationship was found between protein content and the average particle size of the fractions. In contrast, a reverse relationship was found for the fiber content. • Soybean meal flour was fractionated via dry tribo-electrostatic separation. • The impact of voltage and flow rate on protein and fiber enrichment was investigated. • Laminar airflow and high voltage resulted in modest protein and fiber enrichments. • Protein and particle size of the fractions were directly correlated at laminar flow. • The protein and fiber were uniformly enriched along the negative electrode.

On the separation mechanism of high vibration frequency compound dry separator and multi-parameter optimization

ABSTRACT Dry coal separation is the key technology for coal separation in arid and water-scarce areas. The content of −6 + 1 mm coal gradually increases, and the weak gravity affect of this part of coal restricts the separation effect, causing serious resource waste and environmental pollution. In this paper, a process intensification method for compound dry separation based on high-frequency vibration was proposed to improve the separation effect of fine coal. The kinematic characteristics of the bed surface with high-frequency vibration was captured by the three-channels acceleration sensor, and the motion trajectories of different regions on bed surface were reconstructed. The separation area was located at the front end of the vibrating bed, and the elliptical trajectory promoted the material to roll. However, the tail of the bed showed a linear trajectory, the main team to the transport of the material. And then the force characteristics of various density particles were studied by using spherical inertial sensors. Compared with low-density particle swarm, the collision between high-density particles was more obvious, causing serious loss of kinetic energy, which increased the motion difference of particles with different densities. Furthermore, the significance of the effects of vibration frequency, bed inclination and air velocity on the separation effect of −6 + 1 mm coal and the interaction between the factors were investigated. Furthermore, the influence of vibration frequency, inclination, and air velocity on the separation effect and the interaction among various factors were explored. The influence of frequency and inclination was more obvious than that of gas velocity. And then a mathematical model was established to predict the calorific value of clean coal. The results illustrated that at a vibration frequency of 37.52 Hz, a bed inclination angle of 13.69°, and an air velocity of 2.26 m/s, the calorific of product was increased from 4306 kcal/kg to 5868 kcal/kg, and the heat efficiency reached 90.18%. The results provide a referable way to realize the large-scale and high-efficiency dry separation of fine coal.

Zircon Concentrate Enrichment by Dry Magnetic Separation and Centrifugal Air Separation

The possibility of enrichment and radioactivity reduction of zirconium concentrate obtained at the Obukhovsky mining and processing plant, located in the North Kazakhstan region, was investigated. The zircon concentrate was enriched and deactivated by dry magnetic separation and centrifugal air separation. The elements distribution over the grain surface of the obtained fractions was studied and the particle size distribution was determined by energy dispersive X-ray spectroscopy. The characteristics of the initial zircon concentrate were determined. The average particle size was 70 µm, the bulk density was 2.21 g/cm3, the true density was 4.05 g/cm3, the activity was 10.3 ± 0.6 kBq/kg, and the ZrO2 content was 44.85 wt.%. Dry magnetic separation was carried out at a magnetic induction value of 1.3 T in the separator working area and a feed rate of 5 g/min. Centrifugal air separation was carried out using a rotary classifier at rotor speeds of 3000, 980, and 600 rpm, consuming 2000 Nm3 of air per hour and a concentrate flow of 20 kg/h. The scheme of zircon concentrate processing to produce three final products was proposed. The first is the zircon concentrate having a low activity (ZrO2 content = 55.4 wt.%, P = 5.8 ± 0.6 kBq/kg). The second is the titanium-containing fraction having a low zirconium content (ZrO2 content = 17.7 wt.%, P = 14.2 ± 0.6 kBq/kg). The third is the concentrate having a considerable zirconium content and high activity (ZrO2 content = 23.5 wt.%, P = 12.8 ± 0.6 kBq/kg).

Kelimpahan dan Jenis Mikroplastik pada Sedimen Lamun di Perairan Nusa Dua, Bali

The Indonesian archipelago, especially Bali, has extensive coastline and marine waters. However, it is undeniable that some of these waters contain much plastic waste. Nusa Dua waters are located in the Bali Province area with many complex activities, ranging from port activities, water sports, tourism, restaurants, hotels, fishing activities, and others, so they have a high potential for plastic waste pollution. Plastic waste that floats in the ocean will degrade and become small debris called microplastics. Marine plastic debris is divided into several varieties based on size. It is called microplastic for those less than 5 millimeters in length; for those above 5 mm and up to 25 mm, it is mesoplastic. This study aimed to determine the abundance and types of microplastics found in Nusa Dua. This research was conducted in November-Desember 2021. Sampling was carried out in situ with the simple random sampling method of 400 grams of each sample at ten stations. Sediment sampling was carried out using a shovel. Then the ex-situ processing was carried out by drying wet sediment, weighing dry sediment, density separation, filtering, and visual sorting. The results showed that the seagrass sediments in Nusa Dua waters were contaminated with microplastic. Four types of microplastic were found: fragment, fiber/filament, film/soft plastic, and foam. As many as 17 particles fragment the type of microplastic that dominates. The dominant color is blue. The highest total abundance of microplastics was found at station 6, as much as 35.1 particles/kg with different densities of seagrass species at each station. The density of seagrass species itself reaches the range of 1.2 stands/m2

Experimental study of oil shale separation using binary medium by pulsed fluidized bed

ABSTRACT A large amount of the<6 mm fine particle oil shale created during mining and processing is frequently discarded, creating waste and an environmental hazard. A suitable fluidized dry separation technology would allow that fine particle to be de-ashed and improve the oil shale quality for effective utilization. This paper studies pulsed fluidized beds to determine the effectiveness of pulsation frequency, fines content and operating gas velocity on fluidization and separation of the fine oil shale. It was found that the introduction of fine particles could significantly improve the fluidization quality. When the content of fine particles is 5%, the average density of the bed is~2.3 g/cm3. The effective separation of the 6–3 mm oil shale was achieved using a mixed medium, with optimal separation conditions of 5% fine particle content, 4 Hz pulsation frequency, and 1.5U mf gas velocity. Finally, high efficiency dry beneficiation of 6-3 mm oil shale in pulsed fluidized bed was achieved, which is of great significance for future industrial applications.

Investigation of Particle Motion in a Dry Separation Fluidized Bed Using PEPT

Developing dry separation methods to replace the commonly used water-based separation has become crucial due to increasing water shortages. One of the candidates for dry processing is gas–solid fluidized beds. The bed behavior and solid motion in fluidized beds have been investigated using various visual and numerical methods for decades. However, there are not enough studies focused on the separation behavior of the fine particles. This work details the investigation of particle motion through a fluidized bed using the positron emission particle tracking (PEPT) technique. Single-particle tracking is a powerful mechanism providing knowledge about separation mechanisms through direct visualization of the particle trajectory determined from recording the particle position over time. In this study, the movements of different-sized beds were characterized by tracking an activated single quartz particle and then by tracking an activated single hematite particle. The separation behavior of a heavy particle was determined for different-sized fractions.

Separating efficiency of ferromagnetic particles and principle of low-intensity dry magnetic separator under different air supply modes: Based on multi-physical modeling

Separating efficiency of ferromagnetic particles and principle of low-intensity dry magnetic separator under different air supply modes: Based on multi-physical modeling

Nepheline Syenite Beneficiation for Glass and Ceramics Industries

This study aims to treat Nepheline syenite for the glass and ceramics industries. Nepheline syenite has many uses in the glass and ceramics industries. It uses to lower the melting point and fuel savings. In the glass industry, nepheline syenite acts as a source of alumina, which increases resistance to scratching and breaking, improves thermal endurance, and increases chemical durability. A series of processing methods such as dry magnetic separation, flotation, and leaching methods were used respectively to treat nepheline syenite ore. In this paper, the results of combined magnetic, flotation, and leaching Processes of the cleaner concentrate having 0.1% Fe2O3 and 23.25% Al2O3.

Effect of 3–0 mm fine coal migration characteristics on high sulfur lignite separation in compound dry cleaning apparatus

Coal is the significant basic energy to promote the national economic development. Promoting the energy development is of great significant to realizing the energy strategic goals of Carbon Peak and Carbon Neutrality. In this paper, the influence of the migration behavior of 3–0 mm pulverized coal in the bed space on the separation of high-sulfur lignite using compound dry separation bed was mainly investigated. The migration characteristics of differentiated density and size particles in the bed space was emphatically analyzed and the optimum leading density and particle size composition to form autogenous medium bed were determined. The influence of vibration intensity and airflow velocity on the spatial stability of bed density was systematically investigated. The distribution law of low-grade high-sulfur lignite in compound dry separation bed was analyzed and the distribution area of bed products was determined. The experimental results show that when ρ = 1.8–2.0 g/cm3, d = 0.5–0.25 mm, the pulverized coal particles are distributed uniformly along bed height direction and the fluidization quality of bed reaches the optimum and they are the optimum leading particle size and density composition for forming autogenous medium bed. As the vibration amplitude and frequency increase, the density standard deviation decreases firstly and then increases. When A = 2.4 mm, f = 21 Hz, the density stability of bed space reaches the best and the influence of vibration frequency on the spatial stability of bed density is more sensitive compared with the influence of vibration amplitude. Under the condition (A = 2.4 mm, f = 21 Hz), when the airflow velocity range is Uv = 0.112–0.203 m/s, the bed density could keep being distributed uniformly and stably. Under the optimum operating conditions, the compound dry separation tests for low-grade high-sulfur lignite was conducted. The distribution law of sulfur content in the bed was analyzed and the distribution area of bed products was determined. Area Ⅰ is the low density material separation area; Area Ⅱ is the middle and high density product transition and separation area; Area III is the high density product migration area. The yield of clean coal is 73.06 % and the sulfur content, ash content and caloric value are 0.96 %、9.37 % and 12.38 MJ/Kg, respectively. The probable value (Ep) is 0.08 g/cm3 and the high-precision separation of low-grade high-sulfur lignite using compound dry separation bed has been realized.

The Possibility of Implementation of West Ukrainian Paleogene Glauconite–Quartz Sands in the Building Industry: A Case Study

The integrated use of minerals facilitates the reduction in the impact of mining on the environment. Many industries are in need of quartz sand in huge quantities. Quality requirements for quartz sand often refer to a high percentage of SiO2 and low content of Fe2O3, as well as the absence of clay impurities. The extraction of conditioned quartz sands and their close geographic location to consumers are economically profitable. Due to their wide distribution in Ukraine and their subsurface occurrence, glauconite-bearing Paleogene sands attract special attention. It has been experimentally confirmed that such sands are capable of dry magnetic separation. As a result of dry magnetic separation, three magnetic fractions and a nonmagnetic fraction were isolated. Glauconite was the dominant mineral in the magnetic fraction at 0.8 Tl. Their content was 5.1% and 2.8% in sand, respectively. The nonmagnetic fractions obtained from two studied samples were at 80.4 and 80.7%, respectively. XRF analyses showed that in each nonmagnetic fraction the content of SiO2 is at 96.9 wt.% and 93.7 wt.%, and Fe2O3 at 0.26 wt.% and 0.87 wt.%, respectively. In XRD, the nonmagnetic fractions contained 94.8% and 93.1% of sand, and 0.8% and 1.9% of glauconite, respectively. The values of the fineness moduli for the nonmagnetic fractions were 1.10 and 1.85. The size classes of quartz sands were 0.63 + 0 mm and −0.8 + 0 mm. Compared with current Ukrainian standards, the nonmagnetic fractions can be used in the building industry as well as in the manufacturing of glass, with the addition of a certain amount of glass from recycling.