Comparing Dry and Wet High-Intensity Magnetic Separation for Iron Removal from Low-Grade Magnesite Ore

Introduction. I. The Physical Principles of Magnetic Separation. Principles of magnetic beneficiation. Magnetic units. Magnetic properties of minerals. Generation of magnetic field in magnetic separator. Measurement of magnetic properties. II. Review of Magnetic Separation Techniques. Dry low-intensity magnetic separators. Wet low-intensity magnetic separators. High-intensity magnetic separators. Wet high-intensity high-gradient magnetic separators. Superconducting magnetic separators. Laboratory magnetic separators. III. Theory of High-Gradient Magnetic Separation. Theory of single-wire particle capture. Theory of capture in multi-wire matrices. Particle capture by ferromagnetic spheres. Particle capture in a real matrix. Magnetic flocculation. Open-gradient magnetic separation. IV. Practical Aspects of Magnetic Separation. Selection of magnetic separation technique. Dry magnetic separation. Wet magnetic separation. Magnetic field. Matrix. Flow velocity. Pulp density. Feed rate. Rinse and flush water. The effect of particle size. The speed of rotation. Pre-treatment of pulp. The selectivity of separation. Comparison of wet high-gradient magnetic separators. Magnetic flocculation. V. Industrial Applications of High-Gradient Magnetic Separation. Minerals treatment. The magnetic beneficiation of coal. The magnetic beneficiation of fly ash. The application of HGMS to waste water treatment. The application of HGMS in nuclear industry. Magnetic filtration of gases. VI. The Economics of Magnetic Separation. Energy costs. The cost of magnetic separators and their economic comparison. The economics of mineral treatment by magnetic separation. Appendices: List of symbols. List of abbreviations. Values of physical constants. Conversion of units. Definitions of derived units. List of selected companies manufacturing magnets, magnetic separators, magnetic measuring instruments and matrices. Bibliography. Subject Index.

Preface. 1: Principles of Magnetic Treatment. 1.1. Magnetic separation and innovation. 1.2. Principle of magnetic separation. 1.3. Fundamental quantities of magnetism. 1.4. Magnetic properties of materials. 1.5. Magnetic properties of minerals. 1.6. Measurement of magnetic properties. 1.7. Sources of magnetic field. 2: Review of Magnetic Separators. 2.1. Dry low-intensity magnetic separators. 2.2. Wet low-intensity drum magnetic separators. 2.3. Dry high-intensity magnetic separators. 2.4. Wet high-intensity magnetic separators. 2.5. Superconduction magnetic separators. 2.6. Laboratory magnetic separators. 2.7. Eddy-current separators. 2.8. Separators with magnetic fluids. 3: Theory of Magnetic Separation. 3.1. The forces and the equations of particle motion. 3.2. Particle motion in drum and roll separators. 3.3. Separation of particles by a suspended magnet. 3.4. High gradient magnetic separation. 3.5. Linear open gradient magnetic separation. 3.6. Magnetic flocculation. 3.7. Magnetic separation by particle rotation. 3.8. Separation in magnetic fluids. 3.9.Eddy-current separation. 4: Design of Magnetic Separators. 4.1. Introduction. 4.2. Design of circuits with permanent magnets. 4.3. Design of iron-core electromagnets. 4.4. Design of solenoid magnets. 4.5. Design of drum magnetic separators. 4.6. Design of a magnetic roll. 4.7. Design of a ferrohydrostatic separator. 5: Practical Aspects of Magnetic Methods. 5.1. Selection of magnetic separation technique. 5.2. Dry magnetic separation. 5.3. Wet magnetic separation. 5.4. Magnetic flocculation. 5.5. Demagnetization. 5.6. Separation in magnetic fluids. 5.7. Magnetism in other areas of material handling. 6: Industrial Applications. 6.1. Treatment of minerals. 6.2. Nuclear industry. 6.3. Waste water treatment. 6.4. Magnetic carrier techniques. 6.5. Magnetic carriers and separation in biosciences. 6.6. Recovery of metals from wastes. 6.7. The applications of ferrohydrostatic separation. 7: Innovation and Future Trends. 7.1. Introduction. 7.2. Science and technological innovation. 7.3. Magnetic separation and innovation. 7.4. The current status of magnetic separation technology. 7.5. What the future holds. 7.6. Research and development needs. List of Symbols. Bibliography. Index.

Kingdom of Saudi Arabia has huge low grade talc deposits with high iron content (7.63 % Fe2O3) and low silica content (55.43 % SiO2). This paper aims at investigating the amenability of processing the ore to meet filler specifications. This was firstly tried using wet or dry magnetic separation. Secondly, the ore was upgraded using flotation. In applying magnetic separation technique, Carpco induced roll and Boxmag Rapid magnetic separators were used. The main studied variables were: magnetic field intensity, the Carpco roll speed, feed rate and feed size. Denver D-12 flotation cell was used for flotation tests. The parameters pH value, pulp density, collector type and dose were optimized. The obtained results showed that using Carpco dry magnetic separator at optimum conditions produces a talc concentrate having 1.49 % Fe2O3. Wet magnetic separation under optimum conditions using Boxmag can lead to a talc concentrate having 1.33 % Fe2O3. The cleanest flotation concentrate has an iron content of 1.12 % Fe2O3. All these products can be used as filler in paper industry only. However, using flotation for cleaning the Carpco concentrate resulted in a final concentrate of 0.69 % Fe2O3 and 63.23 % SiO2 which has many industrial applications especially as filler.

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.

Owing to its unique properties, pyrophyllite is an economical alternative to many minerals in different applications. The presence of iron-bearing minerals in Saudi pyrophyllite hampers its industrial uses. The aim of this study was to examine the removal of iron from Saudi low-grade pyrophyllite ore using two approaches. The first approach involves dry high-intensity magnetic separation, whereas the second approach involves microwave pretreatment of the ore before dry magnetic separation. For the first approach, the studied operating parameters were roll speed; feed rate, field intensity, and feed particle size. For the alternative approach, microwave treatment followed by dry magnetic separation, the microwave irradiation time and the magnetic field intensity were studied. The results show that the combined microwave treatment and dry separation method could provide high-purity pyrophyllite for filler industries. Microwave irradiation for 30 min was optimal to change impurity phases (i.e., pyrite, hematite) into ferromagnetic phases in microwave-treated pyrophyllite samples. At a magnetic field intensity of 2000 Gauss, the 30 min microwave-irradiated pyrophyllite sample achieved an iron recovery of 11.2% in non-magnetic fractions, with a removal efficiency of 89% with an alumina recovery of 91.31%.

Magnetic separation studies for a low grade siliceous iron ore sample

The Urals is one of the unique iron ore provinces of the world, including all the variety of iron ores. Siderite ores are represented by the Bakal group of deposits, in which siderite in mineralogical terms is not a chemically pure iron carbonate, but has an isomorphic admixture of magnesium and calcium, forming sideroplesite and pistomesite. The main iron ore mineral of the siderite ore of this deposit is an isomorphic mixture of iron, magnesium and manganese carbonates, which occur in different quantitative ratios. A scheme for ore dressing is proposed, which includes crushing to a size of 10-0 mm and dry magnetic separation in a suspended state at a magnetic field strength of 52 k/m. The study of dry magnetic separation of siderite ore was carried out on a suspended separator with a constant magnetic field and on an electromagnetic separator 138T-SEM. The resulting magnetic fraction is sent to the baking, subsequent crushing to a size of 2-0 mm and dry magnetic separation in the suspended state. To increase the mass fraction of iron and reduce the mass fraction of magnesium oxide, the magnetic fraction is sent for grinding and wet magnetic separation. The results of the experiments have showed that the enrichment using high-intensity dry magnetic separation of siderite ore from various sections of the deposit, the mass fraction of MgO decreased from 9.4-12.3% to 8.0-10.1%, and the mass fraction of iron increased from 28.8-33.4% to 31.4-40.8%. As a result, a product with a mass fraction of iron 59.3-60.1% and magnesium oxide 10.0-11.3% has been obtained. The developed enrichment technology allows us to obtain conditioned raw materials, which can serve as a promising raw material for PJSC Magnitogorsk Iron and Steel Works (PJSC MMK)

Investigations were carried out, to establish its amenability for physical beneficiation on a low grade siliceous iron ore sample by magnetic separation. Mineralogical studies, with the help of microscope as well as XRD, SEM–EDS revealed that the sample consists of magnetite, hematite and goethite as major opaque oxide minerals where as quartz and kaolinite form the gangue minerals in the sample. Processes involving combination of classification, dry magnetic separation and wet magnetic separation were carried out to upgrade the low grade siliceous 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 dry magnetic separation and it was observed that limited upgradation is possible. The ground sample was subjected to different finer sizes and separated by wet low intensity magnetic separator. Dry beneficiation studies by Permaroll separator indicated that it is possible to get a product with 60.2 % Fe at 22 % weight recovery. It is possible to get an over all concentrate with 54 % Fe at 32.4 % weight recovery by combination of size reduction followed by LIMS and WHIMS.

Physical separation apparatuses; a vibrating screen, a 4-inch hydrocyclone and a Multi-Gravity Separator (MGS) were used to recover phosphorus as MAP (magnesium ammonium phosphate, MgNH4PO4.6H2O) from anaerobic digested sludge of two sewage-treatment plants A and B. For plant A, the MAP grade increased from 0.08% to 88.9% with 90.4% recovery and for plant B, the grade increased from 0.11% to 73.8 with 93.2% recovery. The collected MAP products containing impurities such as organic materials and heavy metals were further upgraded through dry and wet magnetic separation tests at different magnetic flux densities. A dry magnetic separator was tested on both MAP products (MAP-A and MAP-B), while the wet magnetic separation process was exclusively experimented for the removal of impurities from MAP-B. Feed samples, as well as magnetic and nonmagnetic products were analyzed by absorption spectroscopy, XRD, ICP-AES, polarizing microscope observation, and SEM-EDX. The grade of MAP products could be improved by about 4% - 9% after magnetic separation (the most appropriate magnetic force being 15,000 Gauss). During both dry and wet magnetic separation processes, not only heavy metals have been removed, but also nonmagnetic constituents like Al, Ba, and Ca. This may be attributed to the attachment of fine magnetic particles on the nonmagnetic surfaces, rendering them magnetic properties.

Magnetic separation is an indispensable part of magnetic separation, and the dry magnetic separator can be selected under the condition of water shortage in China to ensure that our country can also be selected under the conditions of lack of some resources. The magnetic separator plays a role in improving the grade of ore, purifying solid and liquid materials, and recycling waste. With the application and development of magnetic separation technology, magnetic separation equipment is constantly updating and replacing, and dry magnetic separation has experienced remarkable technological progress over the past twenty years. There are many new ideas and techniques applied in magnetic separators. So far, dry magnetic separators have developed many different applications for mineral and coal processing, for induction roller magnetic separators for chromite. Cross-belt magnetic separator for removing harmful magnetic particles and paramagnetic particles. The lifting roller magnetic separator is used in the heavy mineral industry to separate garnet from monazite and rutile. Rare earth drum magnetic separator for fine feed dry magnetic separation sorting process and rare earth roller magnetic separator for zircon and rutile in heavy mineral sand industry. These magnetic separators have different applications, and the dry magnetic separator is also moving toward large-scale and easy-to-manufacture.

Purpose. The objective of this work in the first stage is to characterize the poor iron ore from the El Ouenza mine. Then, in the second stage, it is a question of valorizing it by high intensity magnetic separation. Methodology. The characterization of representative samples taken from the study area was carried out using several techniques, including X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS), thermogravimetric analysis and differential scanning calorimetry (TGA/DSC), and Fourier transform infrared spectroscopy (FTIR). Processes involving a combination of calcination and high-intensity dry magnetic separation were used to upgrade the poor iron ore to meet the requirements of the steel industry. Findings. The results obtained show that the El Ouenza iron ore consists mainly of ferrous minerals, notably hematite and goethite, as well as a siliceous and calcareous gangue. The treatment results enabled us to achieve a grade of 51.94 % for the sample calcined at 900 °C using a magnetic field of 2.3 T on the size fraction (-0.5 0.125) mm. Originality. The originality of the work lies in the possibility of using combined methods, calcination and magnetic separation, to valorize poor iron ore from the Ouenza mine. Practical value. This study shows that the results obtained by calcination and magnetic separation are very significant. These techniques enable us to obtain a concentrate with an iron content of 51.94 %, bringing value to the steel industry, eliminating the reserves of poor iron ore stored near the mine site and preserving the environment.

This article presents the main results of research on the extraction of iron from the waste of the processing plant stored in the tailings dump. The average sample was classified by granulometric composition and the content of Fe2O3 was determined by the X-ray fluorescence method for each class. It follows from the results of the sieve analysis that the most iron-rich classes are +2 mm and –0.071 mm. The iron content in the +2 mm class approximately corresponds to the iron content in the source ore. When studying samples of grades +0.1–2 mm under a microscope, it was found that magnetite and hematite are bound by clay materials into floccules, which partially disintegrate upon drying. The initial material with a moisture content of 10.7% was pre-prepared for separation: a fraction of +3 mm was dried and removed. The resulting material was separated on a wet magnetic drum separator with sequential cleaning of the non-magnetic fraction in four stages with induction on the working surface of 0.18, 0.3, 0.4, 0.5 Tl. The resulting non-magnetic fraction from wet magnetic separation was separated on a dry roller separator with induction on the working surface of 1.5 Tl. The non-magnetic fraction was divided by screening into fractions: –3+2 mm, –2+1 mm, –1+0.2 mm, –0.2+0 mm. As a result of the experiment, it was found that wet magnetic separation after pre-drying makes it possible to isolate a concentrate with a content of up to 42% by weight of Fe2O3 into an industrial product. The total yield reaches 24.5% at a magnetic field strength of 0.18 Tl. Check-cleaning, as well as dry separation, do not have a significant additional effect. The conducted research and the developed technological scheme have shown the possibility of obtaining iron ore concentrate with an iron content of more than 60% from stored tailings. At the same time, the return of iron to production is 58%.

Microwave heating is an eco-friendly and novel technique for sintering and heating minerals and materials as it has several advantages in terms of phase transformation, energy efficiency, enhancing speed, process simplicity, improved properties. Such heating provides the composite materials to absorb electromagnetic energy volumetrically and transform into heat and produces larger densities as compared to conventional heating. This study focuses on two main objectives: the recovery of ilmenite through a strategic combination of mineral processing equipment, including a spiral concentrator, followed by magnetic and electrostatic separation, and the enhancement of ilmenite concentrate using microwave heat energy on a cleaner magnetic product, followed by electrostatic separation. Continuous magnetic separation results indicate that among the dry high-intensity belt magnetic separator, box mag wet high-intensity magnetic separator and dry rare earth drum magnetic separators, the rare earth magnetic separator yielded the highest quality product. The application of microwave heat energy before the rare earth drum magnetic separator at 1.4 T, followed by high-tension separation, produced the best grade of ilmenite. The magnetic product obtained after microwave treatment contained 98.6% ilmenite, which was further upgraded to a 99.6% ilmenite concentrate through high-tension separation. Therefore, it is recommended that an effective combination of gravity separation, microwave heat energy, rare earth drum dry magnetic separation and high-tension separation be employed to achieve the highest grade of ilmenite concentrate.

Dry magnetic separation (DMS) enables to separate the non-magnetic fraction of iron ores at the initial stage of their concentration and therefore to decrease cost of their further processing. However, a considerable amount of metal is lost in DMS tails at that. The efficiency of DMS considerably depends on difference between the upper and lower limits of the ore coarseness) ore coarseness range), delivered for concentration. At the Magnitogorsk steel-works crushing and concentration plant No. 5 this range is from 50 mm up to 15 mm. To determine the optimal ore size, delivered to DMS, studies accomplished to determine the specific magnetic susceptibility of the magnetite and the burden for the magnetite ore of Maly Kuibas deposit. After the study of different size iron ore separation, a reasonability of the DMS feed size decreasing down to 30–7 mm shown. A possibility to obtain additional product of 7–0 mm size determined, suitable for sintering. It will enable to decrease the amount of material, delivered for crushing and wet magnetic separation, as well as to decrease expenses for transporting and storage of wet separation tails. Peculiarities of fine magnetite ore processing by DMS in a suspended state considered, optimal parameters of the separator determined and its high efficiency for magnetite ore of 7–0 mm size concentration shown.

This study investigated the effects of iron ore roasting on iron ore beneficiation. Hematite-magnetite conversion was comprehensively investigated and characterized by XRD, SEM, and M–H analyses. The magnetic susceptibilities of the materials were shown by Honda–Owen plots. The optimum magnetite transformation conditions were found as 800°C temperature, 10 wt.% coal and 10 min reaction time. Preliminary tests with the unroasted ores were conducted before the optimization and comparison tests. The Box Behnken test design was used for modeling the falcon concentrator separation tests. High-intensity wet magnetic, low-intensity dry magnetic and falcon gravity separators were applied to the roasted and unroasted ores at the optimum test conditions. After conversion, the iron concentrations in the grade that could be sold (>56% Fe) were obtained by the wet magnetic separator and the falcon gravity separator with the recovery yields of 90.87 and 81.72%, respectively. The positive effects of roasting were observed in terms of concentrate yields for the wet magnetic separation and gravity separation methods. However, desired saleable iron concentrates were not achieved by dry magnetic separation experiments, although the recovery yields were raised above 80% after the conversion process.