Wet Magnetic Separation Research Articles

A continuum based numerical modelling approach for the simulation of WHIMS

Wet high intensity magnetic separators are used in magnetic separation of minerals with low susceptibility. The dynamic process of material built-up in the matrix is influenced, among others, by the matrix geometry, gradient and strength of the magnetic field. These factors, however, do change with the built-up of magnetic material in the matrix.Detecting the built-up of magnetic material is crucial to the continuous operation of the separation process. In this study we present a numerical modelling approach for wet high intensity magnetic separation. The electro-magnetic and the fluid flow field are modelled with the finite element method, while the material particles are identified and evolved using the Level-set approach. Such a framework retains the influence of magnetic particles on the surrounding magnetic field and can be used to detect and predict material build-up in the matrix. The model is validated with a benchmark example and the potential of the approach is demonstrated using a simplified magnetic separation matrix example.

Removal of Silica and Alumina as Impurities from Low-Grade Iron Ore Using Wet High-Intensity Magnetic Separation and Reverse Flotation

This study investigates the removal of silica and alumina as impurities from hematite based low-grade iron ore containing 34.18 mass% iron, 31.10 mass% of silica and 7.65 mass% alumina. Wet high-intensity magnetic separation (WHIMS) and reverse flotation (RF) were investigated. In WHIMS process, 93.08% of iron was recovered with a grade of 53.22 mass% at an optimum magnetic density of 10,000 mT, and pulp density of 2% used the L-4 machine. In RF experiments, optimal results showed 95.95% of iron recovered with 51.64 mass% grade using 1 kg/t of 1% alkaline starch as iron depressant and 1:1 mixture ratio of 0.75 kg/t DAA and NaOL as silica and alumina collectors. The designed multi-stage process involving feeding the concentrate from WHIMS into RF process reduced silica to 2.02 mass%, alumina to 1.04 mass% whilst recovering 81.94% of the iron with 67.27 mass% grade. As a result of this research, a process to produce high quality iron concentrate from hematite based low-grade iron ore with high iron recovery rate was constructed.

Up-gradation of banded iron ores for pellet grade concentrate

As per national steel policy vision 2030, around 500 million tons of quality iron ore is required to produce 300 million tons of steel. In this context, the use of low grade banded iron ores (Fe∼ 30-45%, 40-50% silica) is inevitable. Reduction roasting followed by magnetic separation technique is employed to treat such ore. In this work, banded iron ore with 32% Fe is enriched to a concentrate of ∼53-57% Fe using reduction roasting followed by low-intensity magnetic separation technique. A concentrate of 35% recovery with 53% Fe grade was achieved using Wet High-Intensity Magnetic separator at 12000 Gauss. In case of microwave reduction roasting a concentrate of 57.19% Fe grade and 17.82%wt. recovery is obtained at optimum conditions (540W, 3 minutes and 7% charcoal). Whereas, in muffle furnace reduction roasting 52.95%Fe grade and 47.38%wt. recovery concentrate is obtained at 900°C, 8% charcoal and 30 minutes time.

Physical Methods and Flotation Practice in the Beneficiation of a Low Grade Tungsten-Bearing Scheelite Ore

In this paper, beneficiation studies were carried out on a low-grade tungsten-bearing scheelite from Nezam Abad ore with total WO3 grade of 0.11%. Mineralogical studies showed that scheelite is mainly distributed in the ore and gangue minerals include Quartz and Tourmaline. Liberation degree (d80) of tungsten- bearing scheelite is achieved around particles size 150 μm. Gravity concentration, magnetic and flotation methods were conducted by using experimental designs including fractional factorial and response surface methodology. Gravity concentration results indicated that jig separator could not be able to improve tungsten grade in size fraction +600–1750 μm; however, shaking table increased feed grade up to 27.05% with total recovery more than 50% by using four stages concentration in the size range of +125–600 μm. Multi Gravity Separator (MGS) applied on the intermediate products, improved efficiently the total tungsten recovery of the circuit. The results of flotation practice on the pre-concentrated product demonstrated that WO3 grade could be increased up to 9.2% with total recovery of 27.04% by using one stage rougher and four stages of cleaning. Different methods including MGS, wet and dry magnetic separation were considered for upgrading fines from grinding stages; however, only MGS result was satisfactory. The MGS produced a product with WO3 grade 0.64% and total recovery 93%.

Improving wet belt high gradient magnetic separation performance by magnetic length optimization

ABSTRACTExtensive laboratory and commercial test works have been carried out on wet belt high gradient permanent magnetic separation (WBHGMS) and these works demonstrated that it is effective in purification of non-metallic ores such as quartz and feldspar. The WBHGMS process is achieved with a thin plate-type magnet and its length produces a decisive role in the separation performance. In this investigation, the separation dynamics of particles in the inclined slurry in a high gradient magnetic field and the relationship between magnet length and separation performance were analyzed, and a pilot-scale WBHGMS separator was used to purify a quartz ore to confirm the analysis. The separation results indicate that the magnet length has definitely a dominant control on the separation performance of the separator and its performance is connected with the variables such as magnet inclination angle, belt rotation speed and feed particle size. The iron removal rate was increased with decrease in the Fe2O3 grade of non-magnetic product, as the magnet length is increased. Under the optimized operating conditions, the pilot-scale separator produced a non-magnetic product assaying 0.065% Fe2O3 at a mass weight of non-magnetic product of 75.51% and an iron removal rate of 75.46% from the quartz ore assaying 0.20% Fe2O3. This investigation has provided a detailed description on the optimum design for magnet length in a given WBHGMS separator and it is favorable for the performance improvement of the separator.

Co-reduction of Copper Smelting Slag and Nickel Laterite to Prepare Fe-Ni-Cu Alloy for Weathering Steel

In this study, a new technique was proposed for the economical and environmentally friendly recovery of valuable metals from copper smelting slag while simultaneously upgrading nickel laterite through a co-reduction followed by wet magnetic separation process. Copper slag with a high FeO content can decrease the liquidus temperature of the SiO2-Al2O3-CaO-MgO system and facilitate formation of liquid phase in a co-reduction process with nickel laterite, which is beneficial for metallic particle growth. As a result, the recovery of Ni, Cu, and Fe was notably increased. A crude Fe-Ni-Cu alloy with 2.5% Ni, 1.1% Cu, and 87.9% Fe was produced, which can replace part of scrap steel, electrolytic copper, and nickel as the burden in the production of weathering steel by an electric arc furnace. The study further found that an appropriate proportion of copper slag and nickel laterite in the mixture is essential to enhance the reduction, acquire appropriate amounts of the liquid phase, and improve the growth of the metallic alloy grains. As a result, the liberation of alloy particles in the grinding process was effectively promoted and the metal recovery was increased significantly in the subsequent magnetic separation process.

Thermal Decomposition of Arsenopyrite by Microwave Heating and the Effect of Removal Arsenic with Wet-magnetic separation

In order to transform arsenopyrite into pyrrhotite and to decrease As content by less than 2,000 mg/kg, pulp sample and non-magnetic pulp sample were heated in a microwave oven at different heating times and were separated through wet-magnetic separation. As the microwave heating time increased, the phase of pyrrhotite was extended to become arsenopyrite entirely. The melting pores and micro-cracks occurred on the pyrrhotite due to hot spot phenomenon with microwave heating. The heated raw pulp sample (As content : 19,970.13 mg/kg) and non-magnetic pulp sample (As content : 19,970.13 mg/kg) which were heated in a microwave oven for 10 minutes were separated through wet-magnetic separation and magnetic fraction containing less than 2,000 mg/kg of As content was recovered only from the heated sample of magnetic separation. It was discovered that for the sulfide complex ore with As penalty imposed on, if microwave heating and wet-magnetic separation are effectively utilized, magnetic fraction. We expect to be able to obtain ore minerals with an arsenic content below the penalty charge.

Innovative Solutions in Iron Ore Production at Mikhailovsky Mining and Processing Plant

The article describes features of ore reserves and development of processing technologies at Mikhailovsky MPP. New approaches to disintegration of ore and to improvement of dry magnetic separation of unoxidized ferruginous quartzite are evaluated. The scope of the discussion embraces the process of finishing magnetite concentrate, extracted from unoxidized ferruginous quartzite by wet magnetic separation, using the flotation flow chart in the closed and open circuits, as well as with the reverse cation flotation of hematite concentrate from tailings of wet magnetic separation. The authors present engineering solutions aimed at designing energy-efficient horizontal-grate calcinator MOK-1-592 and the technologies to produce different-purpose iron ore pellets.

The Challenge to Scavenge IRON from Tailings Produced By FLOTATION A New Approach: The Super-WHIMS & the BigFLUX Magnetic Matrix

Abstract Tailings recovery has been a constant challenge for most engineers. Along more than five years, GAUSTEC joined major players in the mining Industry to scavenge Iron from tailings produced by flotation making use of WHIMS (Wet High Intensity Magnetic Separation). In the early 1980s, in USA, the US 4,192,738 patent was granted with promising results. Despite this, thirty years have passed with no significant application worldwide. One main reason is reported: the market missed a really high feed capacity WHIMS in order to avoid the huge number of the WHIMS that were available at that time (such projects would typically require more than 20 WHIMS to scavenge iron from tailings produced by flotation plants). Such a huge asset to scavenge low grade iron tailings would not payback. The Mega sized WHIMS launched by GAUSTEC in 2014, the GHX-1400, improved by the Super-WHIMS Technology (18.000 Gauss) and BigFlow Magnetic Matrixes (Gaps smaller than 1.5 mm), faced this challenge. Specially designed ancillary equipment described here also played a decisive role in the scene.

Beneficiation of High-alumina Bearing Iron-ore Slime: A Case Study From Eastern India

ABSTRACTA typical high-alumina containing iron ore slime from the eastern Indian sector containing 58.13% Fe, 6.48% SiO2, 4.9% Al2O3, and 5.35% LOI, have been evaluated to find out whether grinding of the slimes will be beneficial or not for upgrading the slime to generate pellet-grade concentrate with >64% Fe. Liberation studies indicated that there is significant interlocking between the minerals above 0.074 mm and hence grinding was adopted to liberate the minerals. It is found that by one-stage grinding, followed by hydrocycloning and magnetic separation by wet high intensity magnetic separator (WHIMS) can produce desired concentrate with >64% Fe with an yield over 60%.

Preparation of synthetic carnallite and amorphous silica from chromite beneficiation plant tailings

Abstract In this paper, synthetic carnallite (MgCl2 ∙ KCl ∙ 6H2O) and amorphous silica (SiO2) preparation possibilities were investigated by utilizing chromite beneficiation plant tailings which contain 3.44% chromite (Cr2O3) and 30.55% magnesium oxide (MgO) by weight. Firstly, laboratory scale high intensity wet magnetic separator was applied for removing the magnetic materials such as chromite, iron (II ) and manganese (II ) minerals in the tailings. About 85.75% of chromite, 91.22% of MnO and 64.71% of Fe2O3 were removed by single stage magnetic separation. After the magnetic separation, hydrometallurgical recovery was initiated by leaching of the tailings with hydrochloric acid (HCl). Amorphous silica particles and the other solids were separated from the leach solution by filtration. Impurities were precipitated from the leach solution by elevating the solution pH via magnesium hydroxide (Mg(OH)2) adding. The purified magnesium chloride (MgCl2) solution was mixed with potassium hydroxide (KOH ) at stoichiometric ratio. According to the XRD and chemical analysis, the synthetic carnallite was synthesized by controlled heating of this solution at 90-100°C. Also, the amorphous silica with 96.5% SiO2 content and 84.38% recovery yield was obtained by additional magnetic separation treatment.

Alternative flowsheet for rare earth beneficiation of Bear Lodge ore

The Bear Lodge Project is an important rare earth deposit in the United States. While extensive previous studies have settled on a crushing, screening, gravity and magnetic separation process, this study sets out to investigate an alternative flowsheet based on flotation and wet high intensity magnetic separation (WHIMS) to effectively beneficiate the rare earth oxide (REO) content of the Bear Lodge ore. Mineral characterization found ancylite was the dominant rare earth mineral, associated mainly with calcite and strontianite. Electrokinetic studies on the effects of pH, concentrations of various ions (Sr2+, HCO3− and CO32−) and hydroxamate concentrations were performed to establish the electric nature of the Bear Lodge ore. The isoelectric points (I.E.P) of the material in distilled water was around 5.27. The Sr2+ and CO32− ions in solution significantly affected the surface charge of the material. Adsorption studies suggested that the mechanism of hydroxamate adsorption is chemisorption, as hydroxamate adsorption increased on the Bear Lodge ore with an increase in temperature. WHIMS was employed to remove the iron content to reduce the interference of iron in following flotation process and consumption of hydroxamic acid. After cleaner flotation a REO grade of 11.2% at 72.7% recovery from a feed material of 4.5% REO was obtained. In light of the loss of REO in WHIMS process, it is possible to produce a concentrate containing 11.2% REO grade at 61.2% recovery.

Evaluation of Additional Iron Recovery from Iron Ore Tailings

The article demonstrates feasibility of additional iron recovery from the secondary kind of mineral raw materials—dry magnetic separation tailings obtained at crushing and processing factories of Abaza and Irba and wet magnetic separation tailing produced at Abagur processing plant of Evrazruda. Dry centrifugal separation treatment of Abaza tailings–3 mm in size allowed 6.3% of middlings with Fetotal and Femag contents of 40.4 and 32%, respectively; the result of dry magnetic separation of Irba tailings -5 mm in size is 7.7% middlings with the content of Fetotal and Femag 39.9 and 30.8%. Wet magnetic separation of Abagur tailings -0.007 mm in size allowed recovery of 0.6 to 1.45% of magnetic fraction with Fetotal content of 53.3 and 51.6%, respectively, and Femag content of 49.8 and 48.5%. Fitting of modern separators with the magnetic systems based on neodymium–ferrum–boron considerably improves output of the machines (in dry centrifugal separation circuit) and enhances the yield of magnetic product in wet separation of tailings.

Mineralogy and textural impact on beneficiation of goethitic ore

The effect of mineralogy and texture on the beneficiation of goethitic ores from two different origins is highlighted. Sample A having 54.47% Fe with 8.57% loss of ignition (LOI) indicates the presence of vitreous and ochreous goethite, martite and microplaty hematite as the major minerals. Sample B contains 56.90% Fe with 14.4% LOI. There is a pisolithic laterite containing vitreous and ochreous goethite, quartz, kaolinitic clay and there is no hematite mineral. The liberated minerals in −150+100μm size class are 74% for Sample A and 37% only for Sample B which shows that the Sample A appears to be more amenable to beneficiate. A concentrate of 46.7% with 63.22% Fe could be recovered from Sample A while subjected to gravity separation followed by wet magnetic separation. The Sample B does not respond to gravity and magnetic separation due to its complex mineralogy. However, calcination of the Sample B followed by magnetic separation gives the encouraging results. Thus, anomalous behaviour of the goethite dominated ores in beneficiation is attributed to the different textural and liberation characteristic.

Mineralogical and physical beneficiation studies for iron extraction from Bardaskan titanomagnetite placer deposit

In this work, a bench-scale process was developed using mineral-processing methods to recover iron from a placer deposit located in Bardaskan, Khorasan-e-Razavi, Iran. The mineralogical studies were performed by X-ray Diffraction (XRD), X-ray Fluorescence (XRF), Electron Probe Micro-Analyzer (EPMA), and an optical microscope. These studies indicated that titanomagnetite, magnetite, and hematite were presented in the sample as valuable minerals. In contrast, the gangue minerals were silicates such as pyroxene, plagioclase, quartz, feldspar, calcite, and some secondary minerals. The optimum liberation degree of the iron-containing minerals was obtained to be 75 µm with average Fe and TiO2 contents of 5% and 1%, respectively. The analysis showed that magnetite was the main iron mineral, and most of the hematite was formed due to martitization. Also minor ilmenite contents were found in hematite and magnetite in a blade form. The maximum TiO2 content in the magnetite lattice was 19%, only 8% of which was recovered to the magnetic product. Eventually, an iron concentration flow sheet was developed, which included the removal of a major part of silicates and then iron minerals by a low intensity wet magnetic separator. The final product contained 55, 7.8, and 0.77% of Fe, TiO2, and V2O5, respectively, which can be used for iron production, and V2O5 extraction (as the by-product).

Controlled reduction of red mud by H2 followed by magnetic separation

The current study presents a novel processing approach for the separation of the iron oxide from Red Mud (RM), based on the gentle reduction by hydrogen in static conditions followed by wet magnetic separation. The conversion degree of hematite, initially contained in RM, to magnetite was investigated in relation to reduction time, temperature, and the H2 supply. The maximum achieved conversion reached 87% at 480°C. The phase transformations during the thermal reduction were investigated via X-ray diffractometry, Mössbauer spectroscopy, electron microscopy, and magnetic measurements. After reduction at the optimal conditions, the reduced RM sample was subjected to magnetic separation and a magnetic fraction with over 54wt% magnetite concentration was obtained. Such magnetic fractions could be used as a feed in the pig iron industry, while the non-magnetic fraction could be further treated in order to recover the rare earths or to be used as a raw material for building materials.

Magnetic Field Characteristics of Wet Belt Permanent High Gradient Magnetic Separator and its Full-Scale Purification for Garnet Ore

Purification of non-metallic ores has received considerable attention in the recent decade. In this investigation, the magnetic field characteristics of the innovative plate-type permanent magnet in wet belt permanent high gradient magnetic separator (WBHGMS) were analyzed; then, its full-scale purification of a garnet ore was introduced, and its performance dependences on the key operational parameters, i.e., magnet length, belt rotation speed, and feed particle size, were respectively examined. The separator produced a high-quality non-magnetic product assaying 2.00% Fe at an iron removal rate of 95.00% from the ore assaying 13.10% Fe. It was thus concluded that this WBHGMS separator has provided a promising method for the purification of non-metallic ores.

Improvement the Quality of Egyptian Kaolin for Industrial Applications

The present work aims to study a physical beneficiation of the Egyptian Kaolin from Kalabsha by using a wet high intensity magnetic filter. Since kaolin clay is an important for different industrial applications, but the presence of coloring materials such as iron and titanium, make it unusable for industrial applications as it affects the brightness and whiteness property. Improvement the quality of kaolin was carried out using magnetic separation in a two scale, the first one is a laboratory scale and the second one is a semi pilot scale. Experimental work involved crushing, disintegration, hydrocycloning and magnetic separation. Results showed that the whiteness of kaolin was improved through the application of wet high intensity magnetic separation technique, as in a laboratory scale, about 48% by weight of a non magnetic fraction of kaolin with 0.7% TiO2 and 0.55% Fe2O3 was obtained. The TiO2 % was decreased from 3.56 % to 0.7% with about 87% removal. This leads to increasing the whiteness of kaolin from 86% of the original kaolin to 91% in non-magnetic kaolin. While in a Semi pilot plant two products were obtained. The first is a non magnetic fraction which represents about 74% by weight with 0.56% titanium oxide and 0.49% iron oxide. The second is a middling fraction represents about 10% by weight with 0.76% titanium oxide and 0.49% iron oxide. Finally a material balanced flow sheet is developed for upgrading of Egyptian kaolin to be used for different industrial applications.

PREPARATION AND SEM-EDX-XRD CHARACTERIZATION OF MAGNETIC ZEOLITIC MATERIALS OBTAINEDFROM COAL FLY ASH

A low-cost magnetic zeolitic material was synthesized from coal fly ash by means of a new, simple method involving alkaline hydrothermal zeolitization of fly ash (FA) followed by low-intensity wet magnetic separation. Scanning electron microscopy with energy-dispersive X-ray analysis was applied to characterize the composition, microstructure, and morphology of the material. The mineral and synthetic zeolite phases were identified by powder X-ray diffraction. The obtained magnetic zeolitic material (about 53 wt% of the raw fly ash) consisted predominantly of fly ash particles with moderate to high Fe content (10 - 60 wt%), covered with 2-3 m thick shell of zeolite A crystals with fine crystals of zeolite P on them. Small iron oxide particles captured in larger iron-lean (< 2 wt%) zeolitized FA particles were also present in the product. Occasionally, uncovered iron oxide particles were detected, as well. The obtained magnetic zeolitic material could be easily manipulated in water suspension by means of low-intensity magnetic field and has potential application as an adsorbent for the removal of water contaminants from large volume effluents.

Research of the Interaction of Mechanically Activated Fillers Based on Silica and Cement Paste

The influence of grinding silica-containing raw materials in various mills on the reactivity of fillers at their contact with cement has been researched. The analysis of the research has shown that as a result of mechanical treatment of the feedstock a significant increase in its activity can be achieved. Thus, the greatest effect can be obtained by the use of mechanically activated filler of quartz sandstone and wet magnetic separation waste, ground in a planetary ball mill. It has been proved that this is due to the formation of Bronsted acid sites on the surface of fillers, which are capable of forming strong hydrogen bonds with the cement hydration products and of participating in ion exchange reactions intergranular contact formation. There is a pronounced dependence between the increase in the strength characteristics of the samples of system "mineral filler - cement" and increase of concentration of active sites on the surface of the mineral materials.