Dry High-intensity Magnetic Separation Research Articles

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.

Recovery of Cassiterite and Topaz Minerals from an Old Metallurgical Dump, Eastern Desert of Egypt

Huge amounts of tailing dumps as a result of mines’ blasting operations were impacting economic and environmental problems. Evaluation of one of these tailing dumps of the Eastern Desert of Egypt showed the presence of reasonable amount of cassiterite mineral reaching 0.199% SnO2. The mineral cassiterite was found as finely disseminated particulates, reached to 5 microns, within varieties of quartz-feldspar-hornblende-biotite granitic formations. In the present study, the processing regime considered from the beginning the alignment between reaching cassiterite mineral liberation size, and its extreme brittleness character. Stirring ball milling technique was applied to produce −0.51 mm product with minimum fines as possible, which was left aside for a separate study. The ground product −0.51 + 0.074 mm was subjected to joint shaking table/dry high intensity magnetic separation techniques after splitting it into two fractions, −0.51 + 0.21 mm and −0.21 + 0.074 mm. Each fraction was separately subjected to “Wilfley” shaking table. At optimum conditions, a shaking table concentrate was obtained with 0.29% SnO2 and an operational recovery reached 96.94% from a feeding contained 0.19% SnO2. The heavies and the two middling products after shaking table were directed separately after dryness to dry high intensity magnetic separation using “Eriez” rare earth roll separator, meanwhile the light fractions were rejected. Mathematically designed experiments were applied to optimize the separation process. At optimum conditions, a final cassiterite concentrate was obtained with 11.25% SnO2, and an operational recovery 94.08%. In addition, a topaz mineral concentrate was separated at splitter angle 65˚.

Beneficiation of Low-Grade Rare Earth Ore from Khalzan Buregtei Deposit (Mongolia) by Magnetic Separation

The global demand for rare earth elements (REEs) is expected to increase significantly because of their importance in renewable energy and clean storage technologies, which are critical for drastic carbon dioxide emission reduction to achieve a carbon-neutral society. REE ore deposits around the world are scarce and those that have been identified but remain unexploited need to be developed to supply future demands. In this study, the Khalzan Buregtei deposit located in western Mongolia was studied with the aim of upgrading low-grade REE ore via magnetic separation techniques. The total REE content in this ore was ~6720 ppm (~3540 ppm light REE (LREE) + ~3180 ppm heavy REE (HREE)) with bastnaesite, pyrochlore, synchysite, and columbite-(Fe) identified as the main REE-bearing minerals. As the particle size fraction decreased from −4.0 + 2.0 mm to −0.5 + 0.1 mm, the recovery by dry high-intensity magnetic separation (DHIMS) increased from 20% to 70% of total rare earth oxide (TREO) while the enrichment ratio reached 2.8 from 1.3. Although effective, gangue minerals such as quartz and aluminosilicates were recovered (~22%) due most likely to insufficient liberation. Meanwhile, the wet high-intensity magnetic separation (WHIMS) could produce a magnetic concentrate with TREO recovery of ~80% and enrichment ratio of 5.5 under the following conditions: particle size fraction, −106 + 75 μm; feed flow rate, 3.2 L/min; magnetic induction, 0.8 T. These results indicate that combining DHIMS and WHIMS to upgrade the low-grade REE ore from the Khalzan Buregtei deposit is an effective approach.

Physical processing for polymetallic mineralization of Abu Rusheid mylonitic rocks, South Eastern Desert of Egypt

AbstractIn this study, the mineralogical content of Abu Rusheid mylonite sample was investigated and revealed that the sample is essentially composed of quartz and feldspar (72.14% mass), muscovite (16.6% mass), and contains heavy economic polymetallic minerals of about 2.65% by mass. By studying the differences in the physical properties of this mineral content, a proposed flow sheet was set up to explain the successive physical upgrading steps for concentrating and separating the valuable minerals content and getting rid of the associated gangue minerals. Industrial, economic and strategic polymetallic minerals were identified at Abu Rusheid mylonite sample, including cassiterite, titanite, brass, kasolite, monazite, and uranothorite. A group of sulfide minerals also existed as pyrite, arsenopyrite, galena, and molybdenite in addition to the presence of fluorite and iron oxides bearing rare earth elements (REEs) and base metals. Using dry high intensity magnetic separation followed by wet gravity separation and flotation, three concentrates were obtained; heavy paramagnetic concentrate (monazite, columbite, brass, and jarosite), heavy diamagnetic concentrate (zircon, kasolite, uranothorite, cassiterite, and sulphide minerals) and muscovite concentrate for industrial uses. Physical processing of Abu Rusheid mylonite sample was carried out to produce high grade mineral concentrate used as a raw material for chemical treatment to extract economic elements that necessary for several industries.

Primena suve magnetne separacije visokog intenziteta na obogaćivanje niskoprocentne rude gvožđa iz rudnog ležišta Rouina, Alžir

The recent developments of steel and iron industries generated a huge consumption of iron ores which has attracted much attention for utilizing low-grade iron resources to satisfy this increasing demand. The present study focuses on the characterization and enrichment of the low-grade iron ores from Rouina deposit-Ain Defla-. Currently, the ore is used in the cement industry because it is considered a low-grade iron ore. After the sampling process, a physico-chemical and mineralogical characterization was carried out and the results revealed that the sample consists of hematite, limonite and goethite as major opaque oxide minerals whereas silicates as well as clays form the gangue minerals in the sample. The average grade of FeTotal, SiO2 and Al2O3 contents in the raw material collected from the mine of the case study are 30.85%, 23.12% and 7.77% respectively. Processes involving combination of classification, washing and dry high-intensity magnetic separation were carried out to upgrade the low-grade iron ore sample to make it suitable as a marketable product. The sample was first ground and each closed size sieve fractions were subjected to washing followed by drying than dry high intensity magnetic separation and it was observed that limited upgradation is possible. As a result, it was possible to obtain a magnetic concentrate of 54.09% with a recovery degree of 89.30% and yield of 62.82% using a magnetic field intensity equal to 2.4 Tesla at the size fraction [-0.125 +0.063 mm].

Evaluation of Chromite Recovery from Shaking Table Tailings by Magnetic Separation Method

This study aimed to evaluate the chromite recovery from shaking table tailings of Forumad plant by a dry high-intensity magnetic separation. The average feed grade of chromium trioxide (Cr2O3) was 7.62% by XRF. Also, different mineral phases were determined by XRD, identifying the presence of Chrysotile, Augite, Albite, Chlorite and Chromite. Although the Forumad plant usually applies gravity methods utilizing the specific gravity difference between chromite and other gangue minerals, this study applied magnetic separation utilizing the paramagnetic nature of chromite crystals to recover chromite from tailings. 27 tests for 3 factors in 3 levels designed by the Taguchi method with design expert 12 software to determine the optimum conditions for the grade and recovery. Finally, the best condition was identified at 10,000 gauss (or 1 tesla) in the magnetic field intensity, 1 kg/min feeding rate, and 40 rpm drum rotating speed which produced a concentrate with 34.65% Cr2O3 and 59.42% recovery.

Upgrading a manufactured fine aggregate for use in concrete using dry rare-earth magnetic separation

Manufactured fine aggregates are progressively more used worldwide as an alternative to natural sand in concrete. In a recent study by the authors the removal of contaminants from manufactured fine gneiss aggregates by dry rare-earth magnetic separation was investigated. The present work initially demonstrates that single-stage dry high-intensity magnetic separation of the unclassified fine fraction (−2.36 mm) of the aggregate produced by a vertical shaft impact crusher allows simultaneous partial removal of the flaky biotite particles as well as reduction in the proportion of fines, thus improving its potential for application as a replacement of natural sand in concrete. The work then investigates the effect of magnetic field intensity, specific throughput, roll velocity, splitter position and moisture content on the performance of a bench-scale separator following a full factorial design of experiments. The non-magnetic product from an additional test was then used in combination with the coarser (+2.36 mm) unconcentrated fraction produced by a vertical shaft impact crusher in tests in concrete. Concretes with different strengths were prepared and results show that the upgraded non-magnetic manufactured aggregate was able to match the performance of concrete using natural sand, demanding one third less rheology additive, with comparable strengths at 28 days of curing.

Investigation of Efficiency of Magnetic Separation Methods for Processing of Low-Grade Iron Pigments Ore (RED Ochre)

In this research, the efficiency of magnetic separation methods for processing of a low-grade iron pigments ore (red ochre) has been studied. Based on the mineralogical analyses (XRD), thin section and polish studies, the reserve is an iron sedimentary deposit with an average Fe grade of %31.3. The most valuable minerals are Hematite and Goethite and main gangue minerals are Calcite and Quartz. Wet and dry high-intensity magnetic separation methods were applied for processing. The full factorial design was implemented for all of the wet high-intensity magnetic separation (WHIMS) experiments. Factors of magnetic field intensity, rotor speed and feed water flowrate were considered for design. In optimal conditions in rougher stage, WHIMS produced a concentrate with grade %42.92 Fe and recovery %62.23 in magnetic field intensity 1.7 Tesla, feed water flowrate 5 liter per minute and speed of rotor 3 rounds per minute; also after two stage cleaning WHIMS produced a concentrate with Fe grade and Fe recovery of %56.12 and %38.56, respectively. The results of the dry high-intensity magnetic separation for the two coarser fractions showed that size fraction of coarser than 1000 micron produced a concentrate with Fe grade %40.32 and relative Fe recovery %95.11 and size fraction of -1000+150 micron with Fe grade %45. 04 and relative Fe recovery %75.14. The results of experiments show that there is a low capability for improving quality and grade of this ore. Achieved concentrate from experiments could be used as an initial feed of producing pigment.

Influence of particle size on dry high-intensity magnetic separation of paramagnetic mineral

Dry high-intensity magnetic separators are one of the most common magnetic separation methods extensively used for the concentration of paramagnetic minerals based on their magnetic susceptibility, particle size, particle density, and shape. In this paper, the influence of particle size on the separation of the garnet particle in Induced Roll Magnetic Separator (IRMS) was investigated by varying the magnetic field intensity, rotor speed, feed rate, and splitter position. The influence of particle size on a magnetic fraction of Induced Roll Magnetic Separator was analysed as the D50 (μm) and D80 (μm) size. The results show that segregation of the coarser particle is segregated in non-magnetic fraction while finer sized particles are at the magnetic fraction. To understand further, particle size distribution is analysed by Rosin-Rammler equation and the variation of the constants are explained by statistics. Also, the influence of individual variables and their interactions on the segregation pattern is described by analysis of variance method along with response surface plots.

A New Experimental Approach to Improve the Quality of Low Grade Silica; The Combination of Indirect Ultrasound Irradiation with Reverse Flotation and Magnetic Separation

Removal of iron impurities in silica is one of the most important issues in the glass industry. The most noted impurities are surface coating and staining on silica particles; additionally, some cases of inclusions are observed. The prepared silica sample, for this research work, mostly was in the size range of 106–425 µm. Mineralogical studies indicated the existence of goethite, hematite, limonite and pyrite as the major iron impurities. The poor liberation degree of silica particles from clays encouraged the use of ultrasound irradiation to improve the efficiency of reverse flotation. The head sample contained 96.98% SiO2, 0.143% Fe2O3, 1.52% Al2O3, and 0.088% TiO2; Fe2O3 had to be reduced to below 0.04%. The reverse flotation tests were carried out with and without indirect ultrasound irradiation. The lowest Fe2O3 grade of the flotation yield was 0.058% and this was achieved using 2000 g/t of C4 collector with 15 min conditioning at neutral pH. C4 consisted of Aero 801, Aero 825, oleic acid and sodium oleate at equal dosage. As a result, a flowsheet was developed to include indirect ultrasound irradiation with reverse flotation and two stages of dry high intensity magnetic separation. In conclusion, the best product contained 98.43% SiO2, 0.034% Fe2O3, 0.90% Al2O3 and 0.051% TiO2.

Soil washing optimization by means of attributive analysis: Case study for the removal of potentially toxic elements from soil contaminated with pyrite ash

This paper describes a feasibility study of physical soil washing techniques to separate potentially toxic elements, such as As, Cu, Hg, Pb and Sb, in a brownfield affected by pyrite ash disposal. To this end, complete pedological and geochemical analyses were conducted in order to determine the properties of the soil. Afterwards exhaustive lab-scale soil washing tests were performed with the aim to concentrate most of the contaminants into a small fraction of treated soil. The procedures used included gravity separation–heavy liquid assays–, hydrocycloning and wet and dry magnetic separation.Within this context, grain-size classification proved effective only for the treatment of the sizes below 63 μm. Better results were obtained by heavy liquid separation, which was optimal at most grain sizes, except fractions of the soil between 1000 and 2000 μm, and below 63 μm. As regards magnetic separation, dry high-intensity magnetic separation was suitable for the treatment of grain sizes above 500 μm and gave yields similar to those achieved by heavy liquid assays in most cases. The results of the experiments were compared through the novel approach of attributive analysis, and the findings indicated that the separation procedures for pollutants yielded repeatable results. Moreover, an intuitive method of evaluating the performance of the separation techniques by introducing a “success score” was developed. This procedure takes into account not only the various scenarios contemplated by legislation but also the performance of each washing method for each element.All things considered, in feasibility studies for soil washing methods and also for mineral processing purposes, both attributive analysis and the “success score” may be useful for selecting optimal operating conditions, thus facilitating the scale-up of the results. Moreover, the method presented could be used in any operating plant that aims to reduce emissions while at the same time maximizing product outputs.

Phosphorus partitioning and recovery of low-phosphorus iron-rich compounds through physical separation of Linz-Donawitz slag

The Linz-Donawitz (LD) steelmaking process produces LD slag at a rate of about 125 kg/t. After metallic scrap recovery, the non-metallic LD slag is rejected because its physical/chemical properties are unsuitable for recycling. X-ray diffraction (XRD) studies have indicated that non-metallic LD slag contains a substantial quantity of mineral phases such as di- and tricalcium silicates. The availability of these mineral phases indicates that LD slag can be recycled by iron (Fe)-ore sintering. However, the presence of 1.2wt% phosphorus (P) in the slag renders the material unsuitable for sintering operations. Electron probe microscopic analysis (EPMA) studies indicated concentration of phosphorus in dicalcium silicate phase as calcium phosphate. The Fe-bearing phases (i.e., wustite and dicalcium ferrite) showed comparatively lower concentrations of P compared with other phases in the slag. Attempts were made to lower the P content of LD slag by adopting various beneficiation techniques. Dry high-intensity magnetic separation and jigging were performed on as-received samples with particle sizes of 6 and 3 mm. Spiral separation was conducted using samples ground to sizes of less than 1 and 0.5 mm. Among these studies, grinding to 0.5 mm followed by spiral concentration demonstrated the best results, yielding a concentrate with about 0.75wt% P and 45wt% Fe.

Processing of Ferruginous Chromite Ore by Dry High-Intensity Magnetic Separation

ABSTRACTMineral and morphological characteristics of chromite ore strongly affect the separation efficiency while upgrading the low-grade deposits. Usually, chromite ore enrichment is carried out by using gravity separation due to high-concentration criterion between chromite and other minerals. However, chromite ore from Sukinda region, India, is a typical ore body with high iron content in the chromite spinel as well as gangue content in the form of oxide and hydroxides of iron-bearing minerals. So, the separation efficiency reduces by gravity method due to the lower value of concentration criterion. To address this, dry magnetic separation is an alternative approach to separate these iron-bearing gangue minerals from the chromite. This work investigated on the application of different dry high-intensity magnetic separators to separate the chromite grains from ferruginous chromite ore deposits of India. Prior to the separation, two different ore deposits of Sukinda region are subjected to detailed mineral, chemical, morphological, as well as magnetic properties characterization to visualize the separation. Tests confirm the effect of magnetic field strength along with other process parameters that influence the process of the separation of iron-bearing gangue minerals. The results on these separators are related to the influence of mineralogy, process parameters, and magnetic property of minerals, based on the experimental and statistical analysis of the process. Also, effect of desliming of the low-grade deposit prior to the dry magnetic separation is highlighted.

Processing of Lean Iron Ores by Dry High Intensity Magnetic Separation

Dry high intensity magnetic separation (DHIMS) is investigated to process a lean hematite ore. It was found that the feed particle size and the drum rotation speed have significant influences on the separation performance, and a magnetic concentrate assaying 36.22% Fe with 75.97% recovery is achievable from the ore assaying 29.14% Fe at a coarse particle size below 10 mm. While the DHIMS is applied to process a lean limonite ore, a similar separation phenomenon is observed to that of the hematite ore. It was concluded that DHIMS may significantly improve the economic viability for exploration of lean iron ores.

Application of Permanent Dry High Intensity Magnetic Separation for the Processing of Spent FCC Catalyst

This paper discusses the application of permanent dry high intensity magnetic separation to improve the efficiency of Fluidised Catalytic Cracking (FCC) systems used in oil refining, causing preferential removal of deactivated (spent) catalyst from the process. It was shown that this technique can provide efficient separation of spent catalyst from fresh, despite some loss of fine particles. The effects of particle segregation were also investigated, with both magnetic and nonmagnetic particles. Separation was found to be particularly good for material above 90gm, but efficiency decreased below this particle size. The paper concludes with recommendations for the implementation of the technology.

Dry high-intensity magnetic separation developments that enhance product quality and process economics.

Rare-earth magnetic roll separators have been established in numerous industrial minerals processes since the first useful concept was developed in 1981 by the author. Initially believed to be a machine suitable for certain "niche" applications, such as coarse refractory materials, further improved separators have replaced electromagnetic separators in most industrial uses. Major reasons are higher capacity (typically 50 to 200%, sometimes more), greater product recovery and enhanced quality, all at lower cost.The most recent development is a separator that is performing similarly to the most powerful superconducting drum separators for coarse rock particles. Also, a new machine with 3 to 5 times greater capacity per unit compared to prior standard rare-earth magnetic roll equipment (approximately 10 times that of induced magnetic roll separators) is ready for industrial use. Another product development is the extension of the processing width of 100 mm (4") rolls from 1.0 to 1.5 meters (40 to 60").The paper emphasizes gains in product quality and economics by using rare-earth magnetic roll separators at current development stage. Projections for the near future will also be provided.