Wet High Intensity Magnetic Separation Research Articles

Beneficiation of low-grade, high-phosphorus manganese ores of Andhra Pradesh, India, by wet high-intensity magnetic separation plus jigging or hydrocyclone classification

Jigging of the −2.8 +0.7-mm size fraction of a friable, low-grade manganese ore sample from Andhra Pradesh increased the Mn content of a concentrate by 7% to 8%, with an average recovery of 57%. The jig concentrate was mixed with the unjigged −0.7-mm size fraction and ground to −150 μm. The sample was then subjected to wet high-intensity magnetic separation (WHIMS). The magnetic fraction thus obtained showed an increase in Mn content of 6%, but with an overall recovery of only 50%. The results of hydrocyclone classification of −150-μm ground ore indicated that the method is not capable of upgrading the manganese content, as both ferromanganese oxides and aluminosilicate gangue minerals constitute the fine size fraction. However, when the nonmagnetic fraction obtained from the WHIMS of −150-μm ore is subjected to hydrocyclone classification and the underflow obtained is subjected to WHIMS again, an overall recovery of about 50% to 52% is obtained with at least a 7% to 8% increase in the Mn content of the product. The phosphorus content in the product is not reduced by either of the two combinations of methods. The complex association of phosphorus with all the major phases in the ore has been clearly demonstrated from the linear correlation between the distribution ratios of major constituent phases and phosphorus.

Beneficiation of low-grade, high-phosphorus manganese ores of Andhra Pradesh, India, by wet high-intensity magnetic separation

An attempt was made to beneficiate low-grade, high-phosphorus manganese ores of the Garividi-Garbham region of Andhra Pradesh, India, by using wet high-intensity magnetic separation (WHIMS). The distribution behavior of both mass and chemical constituents in different size fractions of a typical highly weathered ore sample was studied to obtain information about the liberation characteristics of various chemical constituents. Magnetic separation indicated that in the +208-μm size fractions, P and acid insolubles were concentrated in the magnetic fractions. However, in the −208-μm size fractions, P and acid insolubles were concentrated in the nonmagnetic fraction because of a lower recovery of the magnetic fraction. Variations in field intensity between 1.3 and 1.75 T had little effect on the recovery and the grade of concentrate. The results also demonstrated that phosphorus was associated with all three major constituent phases, namely, oxides of Mn and Fe and aluminosilicate gangue minerals.

Removal of Iron From Fly Ash for Ceramic and Refractory Applications

The natural resources of refractory raw materials are declining and at the same time the consumption rate is increasing, particularly in iron and steel industries. Any attempt to identify a new raw material source from the waste dumps could solve the national economy as well as environmental problems. In view of this, fly ash from thermal power plant has been identified for use in the ceramic/refractory industries after suitable beneficiation. For this wet high intensity magnetic separation studies carried out on typical fly ash sample indicate that the non‐magnetic fraction (product) containing 24% Al2O3, 67% SiO2, 1.7% Fe2O3could be achieved with 63% recovery. This product is acceptable as a ceramic and refractory raw material after the necessary blending.

Improved method for prediction of heavy metal recoveries from soil using high intensity magnetic separation (HIMS)

In recent years the soil cleaning industry has developed a number of cleaning strategies mostly based on classification techniques. Sometimes, however, those strategies fail for a number of reasons and as a result cleaning targets are not met. Therefore, some soil cleaning facilities have experimented with HIMS as an alternative process step. This paper describes a prediction method based on magnetic separation techniques for use of HIMS separators in soil cleaning plants. Two types of HIMS separators were used. First a (dry) Frantz isodynamic separator (FIS) and secondly a (wet) Jones high gradient magnetic separator (model P40 KHD and model DP 90 Humboldt Wedag). The FIS was used to separate heavy metals from soil and for observation of heavy metal behaviour in magnetic fields. With the Jones P40, pilot-scale experiments were performed to confirm the FIS results. In total six soil samples uncleanable by soil washing plants and three soil samples prepared by laboratory classification were used in the experiments. Furthermore, three soils were treated on full plant scale. FIS experiments indicated that soils can be distinguished by their different magnetic properties and that each soil shows its own characteristic magnetic susceptibility fingerprint. A similarity, however, was observed between the magnetic properties of soils and the magnetic properties of hematite which is a strong indication for the importance of iron in removing heavy metals from contaminated soil. The Jones P40 experiments showed a similar removal efficiency as the FIS for iron but not for the heavy metals. Soils treated with wet HIMS, however, showed considerably lower heavy metal contents than soils only treated with conventional washing techniques, indicating the usefulness of HIMS in cleaning heavy-metal-contaminated soils. Plant-scale treatment of three polluted soils showed that the Jones separator is a feasible technique for soil washing and treatment of heavy metals.

An Approach to Reduce Load on the Acid Leaching Circuit of the Commercial Uranium Recovery Plant at Jaduguda, India

The commercial uranium recovery plant at Jaduguda, Bihar, India, currently treats around 900 tonnes of ore per day from the Jaduguda mine, containing around 0.05% U3O8. Subsequent to removal of the sulphide minerals present in the ore by flotation, nearly 95% of the tailings are being treated in the acid leaching circuit to recover the uranium values. Laboratory investigations on the bulk flotation tailings revealed that around 63% of the uranium values are associated with feebly magnetic material of the tailings. The magnetic product obtained on wet high intensity magnetic separator gave rise to a product containing 0.1% U3O8. The rest of the uranium values were found to get enriched to 0.15% U3O8 in the –20 µm fraction of the non‐magnetic material thereby giving scope to retrieve the uranium values by recovering the slimes. Necessary unit operations needed to be introduced in the plant flowsheet to reduce load on the acid leaching circuit of the commercial uranium recovery plant are discussed.

Enrichment of the Manganese Content by Wet High Intensity MagneticSeparation From Chikla Manganese Ore, India

Manganese ores from Chikla region, Bhandara district, Maharastra, India, by and large are low and medium grade types and need beneficiation to utilise them in ferromanganese industry. Isodynamic separation followed by chemical characterisation of ores from this region indicated their susceptibility to Mn enrichment. Details of characterisation, heavy media and magnetic separation studies carried out on a medium grade manganese ore, containing 44% Mn, 7.8% Fe and 22% acid insolubles, from the Chikla region are presented. By processing the material on a wet high intensity magnetic separator, a product with 51% Mn at 95% recovery could be obtained.

Development and Commercial Test of Slon–2000 Vertical Ring and Pulsating High–GradientMagnetic Separator

Slon–2000 vertical ring and pulsating high–gradient magnetic separator is an efficient industrial equipment for processing weakly magnetic minerals. It has been recently developed at the Ganzhou Non–Ferrous Metallurgy Research Institute. A six–month commercial testwork to process low–grade hematite ore was completed in Chong Changeling Mineral Processing Plant in 1995. compared with WHIMS–2000 wet high–intensity magnetic separator, the grade of the concentrate is by 7.21% higher the grade of the tailings lower by 5.41% and the iron recovery higher by 7.36%. Particularly, the matrix is always clean so that the matrix clogging usual in the WHIMS – 2000 machine has been overcome.

Wet High Intensity Magnetic Separation of Iron Minerals

Four different iron minerals were selected for study, and five size fractions of each mineral were prepared. The magnetic properties of these minerals were measured. The effect of particle size and magnetic susceptibility on wet high intensity magnetic separation was studied simultaneously. It was found that hematite—1 was a strongly paramagnetic mineral, and the effect of particle size in WHIMS was not significant. Goethite and limonite were weakly paramagnetic minerals, and could not be effectively recovered by WHIMS. The magnetic properties of hematite—2 were between hematite—1 and goethite and limonite, and the effect of particle size on WHIMS for hematite—2 was significant.

Modelling wet high intensity magnetic separation: A case study

This paper details a mathematical model of Wet High Intensity Magnetic Separation (WHIMS). The model is parametric in form and takes account of the major operating variables in WHIMS operation. The model predicts particle recoveries as a function of particle size and magnetic susceptibility. Convolution of these predictions with assay data provides predictions of mineral grades and recoveries. The model was validated against data derived from laboratory-scale WHIMS testwork, comprising (i) Mineral grade/ recovery data (ii) Magnetic property measurements. The model predictions provided a close match to the observed trends in the experimental measurements and gave good numerical agreement over most of the operational range. An adequate characterisation of the separator feed and the calibration of the model itself are necessary precursors to using the model for prediction. This paper describes how the application of auxiliary mathematical techniques (based on physical reasoning) can be profitably utilised to achieve these objectives. These auxiliary techniques serve to enhance or transform readily-available data, which would otherwise be insufficient as model input. A significant cost saving in analyses can be achieved this way. The application of the model to evaluating a specific process option is illustrated through a specific case study - the beneficiation of Wolframite slimes tailings. Modelling methods were used to closely investigate the details of the separation, to explore the sensitivities of the separation and to provide guidance on possible post and pre-treatment options. Results are summarised in this paper.

The recovery of hematite and chromite fines and ultrafines by wet magnetic methods

Wet magnetic separation methods for the recovery of hematite and chromite fines and ultrafines were investigated. These methods included wet high-intensity and high-gradient magnetic separation, carrier or “piggy-back” magnetic separation, magnetic field-induced aggregation and magnetic seeding. This investigation indicated that wet magnetic separation is more efficient for fines and ultrafines. This investigation also indicated that other methods can be used to enhance the particle aggregation and/or the magnetic response. The magnetic behavior of these minerals with respect to the magnetizing field, temperature and particle size is also presented.

Clay Mineralogy, Alteration History, and Economic Geology of the Whitemud Formation, Southern Saskatchewan, Canada

AbstractThe Upper Cretaceous (Maastrichtian) Whitemud Formation is a potentially commercial kaolin deposit located in southern Saskatchewan and southeastern Alberta. The Whitemud Formation contains a lower kaolinitic sandstone, a middle lignite and carbonaceous shale, and an upper interbedded siltstone and claystone. The sediments that comprise the rocks of the Whitemud Formation were deposited on alluvial or upper deltaic plains located along the northwest flank of the Williston Basin.Mineralogy and textures were determined by X-ray powder diffraction, scanning electron microscopy, and optical microscopy. Kaolinite abundance increases upward from the underlying rocks of the Eastend Formation through the Whitemud Formation, and the abundance of smectite, micas, and feldspars decreases from the Eastend Formation into the Whitemud Formation. Vermiform kaolinite crystals are in close spatial association with feldspar and mica grains. Near the top of the Whitemud Formation, etched quartz and feldspar grains, and gibbsite suggest the presence of a strong chemical leaching environment.Mineral distributions, presence of root remains, pedologic mottles, grain coatings composed of clay, and soil horizons indicate the Whitemud Formation sediments were modified by intense weathering in a paleosol environment.Kaolin concentrated from selected kaolinitic sandstone deposits, and beneficiated by oxidation, leaching, and high-intensity wet-magnetic separation has a product brightness up to filler quality. Recovery of lowabrasion kaolin is low and viscosity of a fine-particle kaolin fraction is high. Economics of producing a wet-processed filler-grade kaolin is marginal.

Recent developments in magnetic separation of feebly magnetic minerals

Within the last ten years many new concepts and developments have been achieved in the magnetic separation of feebly magnetic minerals by increasing the magnetic field strength and/or its gradient. Open Gradient Magnetic Separators (OGMS) have found particularly increasing application, mainly due to the use of new high duty rare earth permanent magnets and the introduction of superconductive magnets. The conceptional design and the characteristic features of the new OGMS units PERMOS and DESCOS are described, and some examples of their application in minerals separation practice are given. In addition, some further developments of the well-known JONES Wet High Intensity Magnetic Separator are outlined, which ensure much more flexibility now in processing of coarser grained and ultrafine feebly magnetic iron ores as well as in upgrading of magnetite-martite-hematite-limonite ores containing a wide range of susceptibility.

フェライト法による熱水からのＡｓの除去に関する研究

The removal of arsenic from hot water was investigated by the ferrite formation method. The obtained results were compared with ones obtained by the coprecipitation method with ferric hydroxide. The results are summarized as follows.1) Magnetite is formed and arsenic is removed from hot water by the ferrite formation method. The ferrite formation method removes As (III) more effectively at 90°C than the coprecipitation method; less iron ion is needed in order to reduce the filtrate concentration to less than 0.05 mg/l. The formed magnetite particles, including arsenic, are removed by the Wet High Intensity Magnetic Separator, in the filtrate velosity of 2001/h in the magnetic field of over 0.6T.2) The removal of As (III) and As (V) could be explained in terms of the specific adsorption of arsenic ion on the surface of magnetite. X-ray diffraction analysis showed that the lattice constant of magnetite formed by the ferrite formation method increased as the As (V) content increased. This suggests that As (V) is incorporated to some extent into magnetite.

Flotation of uranium from uranium ores in canada: Part I‐flotation results with elliot lake uranium ores using chelating agents as collectors

AbstractAbout 150 flotation tests were done on Elliot Lake ore with 15 reagents as collectors in order to screen and choose an attractive collector for uranium flotation. Several variables were studied including pH, conditioning time and mode of collector addition. The tests were done in a Denver or Agitair subacration cell. The particle size of the ore was kept at 85% below‐325 mesh. Three reagents (Kelex 100, TOPO, and cupferron) were identified as having the most promise. The best results were obtained with cupferron, where 93‐95% of the uranium was recovered in 25‐30% of the mass of original ore. Radium in the tails varied between 15 and 30 pCi/g depending on the mass of uranium floated. Radium was recovered in proportion to uranium in the tests done at neutral pH. The preconcentration results obtained by flotation alone were comparable to those obtained by Raicevic of CANMET using pyrite flotation and wet high intensity magnetic separation of uranium. The consumption of cupferron was 4 kg/Mg ore for each flotation stage. This was 10‐15 times larger than the collector usage in conventional oxide flotation. This scheme did not require other reagents as depressants, activators or modifiers. Reproducibility was good and similar recoveries were obtained with fresh or old ores, and with distilled or mine water. The selectivity of cupferron for uranium in the ore studied was outstanding.

Dielectrophoretic Filtration and Separation: General Outlook

Abstract Electric and magnetic separation have been in use for many years in the mineral and chemical industries. The development of new technologies1 in the field of magnetic separation, such as magnetohydrostatic separation (MHS), high-gradient magnetic separation (HGMS), wet high-intensity magnetic separation (WHIMS), and magnetic filtration (MF), has generated increasing interest in the2–4 behavior of similar methods such as wet dielectric separation5 dielectrophoretic levitation and fractionation, and dielectric filtration6–7 - all using non-uniform electric fields and polarization. In all these cases dielectric particles in a heterogeneous electric or magnetic field are subjected to the action of ponderomotive (gradient) forces.

On the production of iron ore superconcentrates by high-intensity wet magnetic separation

Direct reduction of iron ore to produce electric furnace feed for steelmaking is becoming economically important on a worldwide scale. For this application an iron ore superconcentrate containing less than 2% silica is demanded. Pilot plant and commercial operations have shown that high-intensity wet magnetic separation is well adapted to meet this specification with high recovery and attractive capital and operating costs. Tests with the Jones separator have produced superconcentrates containing less than 1.5% silica with over 90% iron recovery from preconcentrates produced by sizing or by gravity or low-intensity magnetic separation. Estimated total capital and operating costs to produce a ton of superconcentrate by high-intensity wet magnetic separation are $0.43 for retreatment of specular hematite spiral concentrate, $0.47 for Brazilian hematite fines, and $0.49 for magnetite.