Dry Separation Research Articles

Modeling of dry magnetic separation results for weakly magnetic minerals processed in roll separators

Modeling of dry magnetic separation results for weakly magnetic minerals processed in roll separators

Development of a centrifugal dry magnetic separator for separation of fine magnetite ore

Dry magnetic separation (DMS) has been used for separating large magnetic ores, but it produces a low selectivity for fine particles, due to the challenge of dispersing feed materials. A novel full-scale centrifugal dry magnetic separator (cDMS) was developed, and in this investigation, it was used to process a fine magnetite ore, which assays 28.57% Fe in magnetite. The separation results indicate that the cDMS separator is capable of producing a high separation selectivity for magnetite powders. For feed particle size below 0.10 mm, the iron grade of magnetite in concentrate reached 43.07% at 98.38% recovery for magnetite, with the iron grade of magnetite in tailings significantly reduced to 1.33%. It was found that for the material available, the finer particle size for effective separation reached 0–0.037 mm, and the larger particle size reached 2.0 mm, being an excellent separation performance in comparison with typically conventional dry magnetic separators.

Dry Recycling of Lithium‐Containing Material by Forced Tribocharging and Electrostatic Separation

AbstractLithium‐containing components in batteries, electronics, and renewable energy pose material and waste challenges. Ongoing research focuses on eco‐friendly recycling, emphasizing electrostatic separation as a method to recover, for instance, lithium, especially in battery recycling. This study investigates forced dry triboelectric charging and electrostatic separation of powdered materials, with a focus on the charging behavior of lithium aluminate and talcum. The electrostatic separation efficiency for a blend of powders is also evaluated. Collected samples are analyzed via inductively coupled plasma‐mass spectrometry testing to assess component enrichment. Results show successful lithium enrichment from a talcum‐lithium aluminate mixture, highlighting significant separation success.

Investigation of physicochemical characterization and magnetic enrichment of iron ore from Sidi Maarouf deposit

The establishment of a new metallurgical complex in Bellara, located in El-Milia in the Jijel region, is geographically advantageous due to its proximity to the Sidi Maarouf deposit (Algeria). This proximity has been a fundamental motivation for the completion of the current study. The object of research is the quality of iron products from Sidi Maarouf. The research is aimed at developing a treatment process aimed at improving the quality of iron products from Sidi Maarouf, while reducing the impurities of quartz and clay present in this ore. This approach will be based on an approved technological treatment scheme, implemented through an experimental approach to ensure reliable results that meet the requirements of the steel industry. The problem issue revolves around the difficulties encountered in the production of steels due to the natural characteristics of the raw material. In the absence of a physico-chemical characterization of the Sidi Maarouf iron ore deposit, samples taken undergo a series of thorough analyses, including microscopic examinations, X-ray diffraction (XRD), as well as additional chemical analyses using X-ray fluorescence (XRF). The identified minerals are predominantly composed of hematite in terms of iron. As for the gangue, it is mainly composed of calcite and quartz. Through to the pre-treatment process involving washing, we have successfully removed lightweight particles, resulting in a concentrate containing dense particles. This approach was crucial in achieving satisfactory results during the high-intensity dry magnetic separation. As a result of the research it is shown that the enrichment of the Sidi Maarouf iron ore through high-intensity dry magnetic separation, a final concentrate was obtained with a Fe2O3 content exceeding 67 %, along with a significant reduction in silica impurities to 0.92 % and alumina to 0.77 %. It was concluded that this concentrate, derived from the -1+0.5 mm fraction and obtained under a current intensity of 12 A, meets the requirements of the steel industry. Following the work carried out, it is found that the methods of valorization of iron ore through mineralogical processes consistently require a high level of efficiency and performance in terms of equipment and characterization of the products obtained. In the future, iron ore processing will be conducted using innovative methods, integrating advanced technologies to enhance its characteristics while adopting environmentally friendly practices.

A Review on Methods of Cenosphere Separation from Fly Ash

Cenospheres are valuable material contained inside the fly ash. Its low weight, low density, and high strength made it very versatile and can be used in various fields. The way of separating the cenosphere from the fly ash consists of two categories, wet and dry separation. For wet separation, it involves submerging the fly ash inside a mixture made either by pure acetone, pure water, or a mixture of water and acetone with different mixing ratios before stirring the mixture. The cenospheres, floating on top of the mix due to low density, can be collected and dried. The dry separation technique involves putting the fly ash into a cyclone separator at a constant velocity. The fly ash will then move into the bottom of the cyclone. Particles can also be separated by diameter sizes by sieving. By manipulating various parameters, cenosphere yield may differ. This paper is written to help gain more understanding on cenosphere properties and its separation method.

Development of a three-stage process for high coal desulfurization and char yield

Efficient pyrolytic desulfurization with high char yield is a promising yet challenging approach for the cleaner utilization of abundant high-sulfur coal reserves. In this study, we have discovered that a single pyrolysis process under either oxidizing or reducing conditions cannot efficiently remove various sulfur forms while preserving a high char yield. To address this challenge, we propose a three-stage desulfurization process: a low-temperature oxidative pyrolysis (LTOP), a high-temperature reductive pyrolysis (HTRP), and a dry magnetic separation process. LTOP operates in a fluidized bed for only a few minutes to oxidize the diamagnetic pyrite particle surface to Fe2O3 while minimizing char losses. HTRP occurs in another fluidized bed for an appropriate duration to substantially remove organic sulfur while reducing Fe2O3 to highly magnetic Fe3O4 or Fe. Partially magnetized pyrite particles are then removed from the char through magnetic separation. When applied to anthracite coal with a total sulfur content of 4.99%, this process achieves nearly 100% desulfurization for pyritic sulfur and 74.81% for organic sulfur. Ultimately, it recovers 94.5% of the original coal excluding volatiles as char, with 91.6% being low-sulfur char.

Zirconia Enrichment of Zircon from Arikya, Nasarawa State, Nigeria, by Magnetic and Gravity Separation Processes for Use as Reinforcing Agent in Composite Formulation

Acceptable zircon for composite formulation in the aerospace industry requires that the mineral contains a minimum of 65% zirconia (ZrO2). Despite having vast deposits of zircon, Nigeria’s aerospace industry has historically relied primarily on imported mild steel tubes for solid rocket motor cases (SRMCs) construction, resulting in three major challenges: low strength-to-weight ratio, pressure, and temperature containment. In this study, the Arikya zircon deposit located in northern Nigeria was investigated with the aim of upgrading low-grade zircon ore using magnetic and gravity separation processes for use in composite formulation for SRMCs. The dry high-intensity magnetic separator (DHIMS) produced a ZrO2 grade of 52.48%, recovery of 57.99%, and an enrichment ratio of 0.78 with a separation efficiency of 0.56, while the air-floating separator (AFS) generated the highest of 65.52% ZrO2 grade with 70.81% recovery and enrichment ratio of 1.25 with a separation efficiency of 0.25. The ZrO2 content increased from 40.77 to 65.52% after beneficiation. Iron oxide and titanium dioxide contaminants at 0.73 and 0.83% were reduced to 0.66 and 0.54%, respectively, while the specific gravity increased from 4.4 to 4.6 g/cm3. The ZrO2 content and specific gravity were improved to the minimum standard specified for zirconia-reinforced composite application and competed effectively with industrially/globally accepted zircon. These results demonstrated the efficacy of combining DHIMS and AFS to upgrade the low-grade zircon ore from Arikya, Nasarawa State.

Design Of a Dry Coffee Bean Shell Separation Machine Model To Increase Productivity

The research objective of designing a coffee bean skin separator model is to increase work productivity in the ergonomic dry coffee bean skin separation process. The way this dry coffee peel separator machine works is that the steel plates will rotate each other at certain gaps so that they can rub the coffee until it peels off. The design of this dry coffee bean peeling machine is adjusted to the results of anthropometric data measurements. In the previous coffee skin splitting process using an old-fashioned coffee peeler machine where the coffee beans were put in the inlet without sorting the coffee sizes, all coffee sizes were put in to be processed in the machine. Then the peeling plate gap is adjusted and the medium size is selected. As a result of stripping, it was obtained that almost 50% of the coffee beans had not been peeled off, and had to be put back in again. Besides that, the results of the stripping were still mixed with the dirt skin, so it needed to be processed again to clean the coffee. The results of testing the performance of the old model of the peeler with the new model of the improved peeler obtained an increase in performance or an increase in productivity. Increased work capacity of the dry coffee peeler (Kp) = (153.84 -17.24) / 17.24 = 176.88%, while the increase in the quality of well-exfoliated coffee beans (Kw) is = (90.74 – 85 .41)/85.41 = 6.24% thereby increasing productivity.

Mineral Magnetic Modification of Fine Iron Ore Tailings and Their Beneficiation in Alternating Magnetic Fields

In this paper, the properties, mineral magnetic modification, and beneficiation of tailings from the central mining and processing plant in Kryvyi Rih, Ukraine, have been studied. Samples were investigated by X-ray diffraction, X-ray fluorescence, microscopy, and magnetization measurements. The beneficiation was conducted using magnetizing roasting with carbon monoxide followed by dry low-intensity magnetic separation. The effects of chemical, mineral, and granulometric composition on the processing of fine tailings of different sizes sampled at different points of the tailings pond were investigated. Additionally, we proposed a new approach for magnetic separation of fine magnetically modified tailings based on the combination of permanent and alternating magnetic fields. Magnetizing roasting resulted in an enhancement in mass magnetization to 11–62 Am2/kg in comparison with initial values of 0.3–1.5 Am2/kg. After magnetic separation, the magnetic concentrates consisted almost completely of magnetite (with the magnetization of 75–88 Am2/kg) and non-magnetic residues contained major quartz. The content of iron in magnetic concentrates reached 68.5–70.2 wt.% and iron recovery 77–96 wt.%, depending on size fraction. We could conclude that the tailings are represented by fine-grained liberated material that can be effectively upgraded using magnetizing roasting and magnetic separation into two valuable products, such as iron concentrate and quartz powder.

Ultrasound-enhanced separation characteristics of gas-solid fluidized bed for fine-grained fluorite ore

Due to the increasing mechanization of mining, there is an urgent need to develop dry separation technology for effective pre-enrichment of fine-grained fluorite ore and promote the efficient use of fluorite in arid or water-scarce areas. Therefore, we tried to enhance the separation performance of fine-grained fluorite ore by introducing ultrasound into the gas–solid separation fluidized bed. Fluidization test and high-speed dynamic image analysis were used to reveal the mechanism of density separation of two-component materials enhanced by ultrasound. The effects of gas velocity, static bed height, separation time and amplitude transformer diameter on density segregation of two-component materials were further studied. In addition, a gas–solid fluidized bed separation system under the action of ultrasound was established for the pre-enrichment of fluorite ore with different particle sizes. The study showed that the stability of the bed is improved by the introduction of ultrasound. And the separation efficiency was increased by 15.46% compared with ordinary fluidized bed. The possible deviation (E) values of 1–0.5 mm and 0.5–0.25 mm fluorite ore were 0.22 g/cm3 and 0.175 g/cm3 respectively. This study provides new insights into the separation of fine-grained fluorite ore by gas–solid fluidized bed under the action of ultrasound.

Optimizing the removal of iron oxide from Egyptian feldspar ore

The demand for feldspar as a raw material for various industrial applications continuously increases. Feldspar is a primary raw material in manufacturing ceramics, glass, fillers, welding electrodes, and enamel. Feldspar is often associated with iron oxide, which decreases its economic value and hinders its industrial application. The present work aimed at reducing iron oxide content in Egyptian feldspar ore from the Wadi Zerabi locality. Ball milling was used for preparing feldspar feed of size -250+45µm. Carpco dry high-intensity magnetic separation followed by acid leaching processes were carried out in order to decrease the iron contamination and increase the feldspar content. A Box-Behnken statistical design was used to optimize the magnetic separation results. From a feldspar feed containing 1.40% Fe2O3, a non-magnetic concentrate of 0.25% Fe2O3 was obtained. The Fe2O3 removal reached up to 82% with a high yield as the % weight of non-magnetic feldspar reached up to 97.5%. The leaching process further reduced the iron oxide content down to 0.19 %. Also, the feldspar whiteness was improved from 65.17% in the original ore to 85.60% in the leached product.

A novel pneumatic dry high-intensity magnetic separator for the beneficiation of fine-grained hematite

This study focuses on the development of a novel pneumatic dry high-intensity magnetic separator (PDHIMS) (maximum magnetic induction of 2 T) to enhance the efficiency of separating hematite ore fines. Force analysis of the novel separator demonstrated that it can potentially reduce the lower size limit of hematite dry beneficiation from 58 μm to 10 μm. A series of experiments of mixed samples, such as hematite–quartz/feldspar/chlorite/augite indicated that PDHIMS is successful in achieving highly selective separation of hematite particles fine to 13 μm, overcoming the slime coating of −13 μm quartz particles on the surface of −150 + 38 μm hematite particles, and improving the separation efficiency between hematite and poorly intergrown particles (or magnetic gangues). Energy dispersive spectrometer (EDS) and microscopic imaging of the concentrate confirmed that −13 μm particles form stable aggregates and cannot be disrupted by the employed aerodynamic field in PDHIMS, resulting in a notable entrapment of quartz particles within the concentrate. Lastly, the induced roll magnetic separators (IRMS) with gravity feed and airflow feed were selected as the objects compared with the PDHIMS. The comparison revealed that PGHIMS exhibits a marked superiority in eliminating slime coatings from coarser magnetic products.

Dry fractionation for endosperm recovery from a barley malt waste stream

Cereal processing industry removes the fibrous tissues from kernels via abrasive milling, but this tends to remove part of the valuable endosperm components as well. Therefore, endosperm recovery from such abraded barley malt material (53% endosperm and 47% husk) was evaluated for three dry separation technologies. Electrostatic separation recovered 25% of the endosperm at 85% purity and this recovery increased to 39% in a second run, which indicated potential to further improve the setup. Increasingly finer sieves removed up to 40% of the husk with little endosperm loss, but further husk removal up to 95% by the finest sieve reduced the endosperm yield to 54% due to decreasing differences in smallest diameter between the endosperm and husk particles. Air classification outperformed sieving by yielding 71% of the endosperm while removing 95% of the husk, and further, less selective air classification steps could yield up to 94% of the endosperm while still removing 59% of the husk. Moreover, such additional air classification steps currently recovered residual endosperm particles more selectively than electrostatic separation after an initial air classification. Overall, air classification after abrasive milling increased the removal of insoluble matter from malted barley kernels. The loss of soluble endosperm components remained similar to the loss as observed in a single abrasive milling step.

Direct Metal-Free Growth and Dry Separation of Bilayer Graphene on Sapphire: Implications for Electronic Applications

Direct Metal-Free Growth and Dry Separation of Bilayer Graphene on Sapphire: Implications for Electronic Applications

Research on Hydrocyclone Separation of Palygorskite Clay

The separation methods of palygorskite can be divided into dry separation and wet separation. For wet separation, which is more efficient, the centrifuge is the commonly used method but is characterized as having a high cost. It remains a challenge to separate ultra-fine palygorskite with an economical method. This work tried to separate palygorskite using a hydrocyclone with two separation stages. Orthogonal experiments are designed to investigate the influence of feed concentration, feeding pressure, and underflow port diameter on separation performance. The element content, mineral composition, and particle size distribution of the separation products are analyzed, respectively, by XRD, XRF, and laser particle sizers. The apparent viscosity of palygorskite pulp is characterized by a rotational rheometer. The purity of the feed and palygorskite concentrate is measured using an internal standard method. The results show that the purity of palygorskite increased from 45.1% to 64.2%, with a recovery of 95.9%.

Comparing electrostatic separation of soy and lupin: Effect of de-oiling by solvent extraction

Electrostatic separation is a sustainable dry separation technique based on triboelectric charging of different cellular tissue components (i.e. protein bodies and fibres). This research aimed to determine the mechanism behind the ineffective electrostatic separation of soy and if it could be altered by de-oiling. Several scenarios were compared, which involved electrostatic separation of soy and lupin de-oiled with different solvents (none, acetone, ethanol and hexane). Separation of lupin resulted in a higher true protein content (58.5%DM (dry matter) (Nfactor = 5.7)) than separation of soy (45.0%DM protein). Separation was less effective for soy because its protein bodies were still embedded in the cellular structure after impact milling, which was also reflected in the larger particle size and lower small particle dispersibility. De-oiling soy with hexane and extra milling improved the purity of soy protein-enriched fractions (59.6%DM protein) reaching more similar purity as for lupin protein-enriched fractions. The protein purity of lupin fractions could be increased most via the use of polar solvents (acetone and ethanol). Better electrostatic separation after de-oiling and extra milling for soy could be explained by increased liberated protein bodies, which was key towards the improved separation of soy obtaining protein purities closer to that of pure protein bodies.

Ecological and biological bases of creating source material of sea buckthorn (Hippophae rhamnoides L.) on adaptability and productivity for further breeding

The research relevance is determined by the constant striving to improve and enhance sea buckthorn genotypes by using different genetic resources and breeding methods to achieve better adaptability, higher productivity, and fruit quality. The research aims to expand the genetic diversity of sea buckthorn, which combines high productivity and quality for further breeding. Phenology, morphological studies, and evaluation of breeding material for economically valuable traits were carried out according to the methodology for the examination of plant varieties, and molecular genetic studies – according to the polymerase chain reaction method, which is based on multiple copies of a specific DNA region. The formative process in sea buckthorn breeding for adaptability, productivity and quality was expanded by using the gene pool of related forms, which is one of the ways to solve the problems of creating source material for further breeding and is the basis of the research, which established a wide range of formative process by morphological traits and biological properties as a result of the hybridisation of biotypes, which allowed to select valuable hybrids for a set of breeding and, in particular, new forms of Soborna and Adaptyvna Improved were identified, characterised by high winter and drought resistance, productivity and fruit quality, absence of thorns and dry fruit separation, and submitted to the State Variety Testing. The obtained genotypes of sea buckthorn plants combine resistance to high and low environmental temperatures with a complex of other economic traits: disease resistance, low or no thorniness, fruit quality and their suitability for processing and production of products for healthy nutrition. The practical value of the study is based on the fact that the results of the research expand the information on the use of sea buckthorn adaptability, productivity, and quality in breeding, selected and studied in the natural and fallow ecosystems of Polissia and Forest-Steppe of Ukraine. As a result of the study, the best samples were selected and included in the Genetic Bank of Plants of Ukraine as material with valuable horticultural traits and involved in breeding work at the Institute of Horticulture of the National Academy of Agrarian Sciences of Ukraine

An experimental study of triboelectrostatic particle charging behavior and its associated fundamentals

Triboelectrostatic separation is a unique dry particle separation process that has been applied to many industrial applications. However, little attention has been directed to the process of charge transfer during the particle collision and friction which is critical for the success of triboelectrostatic separation. The present study has been conducted to quantify the effects of particle size, collision speed, contact mode (collision or friction), etc. on the charge density, surface potential, morphology, etc. of quartz particles based on macroscopic triboelectrostatic charge measurements and microscopic atomic force microscopy (AFM) characterization. The macroscopic charging performance results showed that the charge to mass ratio of quartz particles depended on process parameters such as feed rate and charger rotation speed and the highest charge to mass ratio reached −56.21 μC/g. The microscopic AFM characterization data reveals that the increase in particle size and collision velocity fundamentally enhanced the triboelectrostatic charging process. The surface potential of quartz increased from −60.60 mV to −477.15 mV with increasing PVC particle size from 280 μm to 1250 μm and similar behavior was observed with increasing the collision velocity from 0.99 m/s to 2.62 m/s. The change in contact mode only changed the magnitude of charge transfer but did not change the polarity of charged particle. The process of charge transfer was accompanied with the change of surface morphology and the degree of change in surface morphology was not directly related to the amount of charge transfer.

Ingredient fractionation for monogastric animal nutrition: the worth of sum of parts versus the whole

Basic agricultural commodities such as cereal grains, pulses and oilseeds can be fractionated into separate products that can be targeted to high value markets within or outside the feed industry. Resulting nutrient-dense fractions that are enriched in starch, protein, fat, or fibre can then be targeted to animals with different nutritional demands. These value-added nutrient fractions might be targeted at the start of fractionating the commodities or result from human food or biofuel production. Fractions enriched in fibre might be targeted to the feed, paper, or wood industries. Two categories of processes can fractionate cereals, pulses, or oilseeds: (1) an up-front process that produces solely or mostly high value ingredient fractions, or (2) a process that separates one fraction for a high-value market. Examples of category 1 include air classification and sieving. Examples of category 2 include bioethanol production from cereal grains and oil extraction from soybean and canola seed. The resulting non-human edible co-products can be fed to livestock. Dry separation is useful to produce protein-rich fractions from pulse grains. Advantages of dry over wet fractionation are continuous flow rather than batch fractionation, absence of effluents and no drying cost. However, wet fractionation creates more concentrated fractions (isolates) of the nutrient of interest, e.g., protein. Category 1 and 2 processes can occur in tandem. For example, oil can be first extracted from soybeans, resulting in soy oil and soybean meal. Subsequently, soybean meal can be fractionated into protein concentrates or isolates with greater protein content than soybean meal. Fractionation usually has at least one main fraction with a target market in food or industry processes yielding products for human use. This approach is logical, because the feed industry is focussed mostly on small margins and large volumes, whereas higher margins per unit of product can be achieved in markets for food, petfood and feed for fish or animals with high nutritional demands. Animal agriculture remains an ideal approach to convert by-products from ingredient fractionation into high value animal protein. The economic implications of value-added processing are thus important, and sustainable animal agriculture plays a key role turning waste streams into a success story. Although ingredients can be fractionated successfully for animal nutrition, especially for higher margin markets such as aquaculture, petfood or animals with high nutritional demands, most ingredients are fractionated for the human food supply or industrial processes. Using the latter approach with at least one high value fraction targeted to human food or industry and then using non-human edible fractions for feed applications, will ensure that the sum of the parts can be worth more than the whole.

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

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