High Intensity Magnetic Separation Research Articles

Mathematical Modeling of Cassiterite Using Certain High Field Strength Elements (HFSE) with Respect to Thermodynamics Principle

The main purpose of this study was to evaluate Cassiterite ore mathematically, using certain selected minerals of high field strength elements (HFSE) with respect to thermodynamic principle and how they control the formation of cassiterite during crystallization of magma. The effectiveness of Cassiterite ore in Extractive Industry depends on the properties of these minerals of HFSE that composed the Cassiterite during crystallization of magma and can be mathematically expressed as Z[X n-x Y x ]O 6 , [X n-x Y x ]O 4 and, [ X n-x Y x ]O 3 as n ranges from 0 to 5 where x depends on’ n’. These minerals contain HFSE and are those that essentially partitioned along the aqueous phase during cratallization magma. Methodologically, 20kg of cassiterite was crushed and pulverized in the laboratory mill machine for an hour, and was taken and sized by sieving into number of size fractions using the automatic sieve shaker for 15 minutes, after processing using high intensity magnetic separator and with the help of ordinary hand magnet of about 0.01Tesla, relative density measure, the relationship between minerals of HFSE can be mathematically established using a Cassiterite model. Mathematically, findings have shown that, the minerals obtained from cassiterite during processing are mainly minerals of HFSE such as tin, ilmenite, columbite, tantalite, zircon, monazite and sand, and as such classified as, Ferri/Ferrous-Columbte, Ilmeno-Columbite Cassiterite type, and Ilmeno-tantalite types and chemical analysis using XRF revealed the following chemical compositions of cassiterite; SnO 2, TiO 2 , Fe 2 O 3 /Fe 3 O 4 , Nb 2 O 6 , Ta 2 O 6, ZrO 2 . At a given chemical equilibrium under standard condition of temperature and pressure, these HFSE are partitioned along the aqueous phase and they set in matrices to form an Ore of these HFSE that is stable with minimum Gibbs free energy and is highly resistance to weathering during weathering breakdown, such as Cassiterite. In conclusion after the comparative analysis among the minerals of HFSE in cassiterite using matrix equations and certain measures such as density, magnetic susceptibility, and their electrical conductivity, it is observed that, the type of reactions that take place during the formation of Cassiterite are oxidized and isomorphous which include complex, isovalent and heterovalent reactions. This means that there was an oxidation of these complexes from one form to the other and substitution of one element to the other according to size and charge during the formation of cassiterite ore from magma. Presumably, if the reactions occur throughout the time of crystallization from the dry melt to an aqueous state with increasing particular trace elements over the others, then at a given chemical equilibrium with minimum Gibbs free energy, cassiterite can be processed in terms of ferrous/ferric – colubite cassiterite type Ilmeno-Columbite Cassiterite type and Ilmeno – tantalite cassiterite type. Finally, the presence or absence of HFSE over the other in cassiterite ore determine their genetic rock origin, in which the amount of titanium - tantalum in Cassiterite increased from alkali rock (magmatic) with ∆G ≥ 0, e.g. nepheline syenite to more silicic, with ∆G > 0, e.g. granite pegmatite (hydrothermal) which gives the account that cassiterite rich in ferrous/ferric -niobium is less dense than the cassiterite rich in titanium-tantalum, therefore as result of this, concise valuable substantive empirical novel model was developed and can be employed to study cassiterite ore. This concise empirical novel model was, ‘Cassiterite’ model designed with the aid of: Matrix equation, Oxidation and the isomorphic process, and can be recommended to study the Cassiterite and the application can improve mineral processing in extractive Industry.

Applicability of carbothermic reduction for upgrading Sri Lankan ilmenite ores: towards converting ilmenite into synthetic rutile by mechanical activation

BackgroundIlmenite and rutile are naturally occurring titanium-bearing heavy minerals. Sri Lanka consists of ilmenite and rutile in placer deposits mainly along the northeast coast. The commercial value of rutile is higher than ilmenite. Therefore, the current study focuses to upgrade Sri Lankan ilmenite ores using commercially available activated carbon as a reducing agent. Ilmenite fraction was initially separated from raw beach sand using an industrial-scale magnetic separator (Wet high-intensity magnetic separator: sixteen pole model). The mixtures of ilmenite and activated carbon (4 to 1 ratio by weight) were milled using a planetary ball mill for one to four hours at one-hour intervals.ResultsThe milled samples were subsequently heated for two hours continuously at temperatures of 800 °C, 900 °C, 1000 °C, 1100 °C, and 1200 °C, respectively. Initial and annealed samples were analysed using X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and X-ray fluorescence (XRF) analyses. XRD pattern of the initial sample was characterized by less percentage of rutile (TiO2) peaks and low crystallinity. However, the number of rutile peaks and crystallinity were increased with respective milling hours and annealed temperature. Besides, XRD analysis indicates a higher number of sharp and intense rutile and elemental iron peaks in the samples annealed above 1000 °C. FTIR analysis of raw ilmenite indicates mainly stretching vibrations of Fe–O. However, vibrational spectral bands around 700 cm−1 in samples annealed above 1000 °C are assigned to Ti–O–Ti stretching vibrations. High TiO2 and TiO2 + Fe2O3 (total) wt. (%) can also be observed in samples annealed above 1000 °C.ConclusionsThe optimum conditions for carbothermic reduction were obtained at 4 h of ball milling of ilmenite with activated carbon and continuously annealing at 1000 °C for 2 h. Carbothermic reduction is applicable to upgrade Sri Lankan ilmenite ores, and thus this method adds value to heavy mineral resources in Sri Lanka.

Effect of Tantalum on Coltan in Cassiterite Using Mathematical Modeling Approach with Respect to Gibbs Energy

The objectives of this study were to evaluate the effect of tantalum on COLTAN in Cassiterite using mathematical modeling approach and how it controls the strength, cell size, magnetization, and density (grade), as well as electrical conductivity of COLTAN in Cassiterite. The effectiveness of COLTAN in Cassiterite in Extractive Industry depends on the ratio of tantalum to niobium in the solid solution during crystallization of magma with respect to Gibbs free energy and can be mathematically expressed as Z[X n-x Y x ]O 6 as n ranges from 0 to 5 where x depends on’ n’. Mathematically, cassiterite consists of small ion lithophile elements, large ionic charge, with intermediate to greater ionic potential and these elements are partitioned along the aqueous phase, if both the aqueous phase and silicate phase coexist together during crystallization of magma. These trace elements include tin, iron; niobium, tantalum, and zircon are incompatible trace elements because of their inability to achieve a charge balance with silicate structure (SiO 4 ) in the silicate magma phase. These elements do not exist as free ions in the magma but form complexes with oxygen in the magma during crystallization. Methodologically, 20kg of cassiterite was crushed and pulverized in the laboratory mill machine for an hour, and was taken and sized by sieving into number of size fractions using the automatic sieve shaker for 15 minutes, after processing using high intensity magnetic separator and with the help of ordinary hand magnet of about 0.01Tesla, relative density measure, triaxial testing machine to measure the strength, the relationship between columbite and tantalite can be mathematically established using a COLTAN model. Findings have shown that, with increasing amount of tantalum atom on COLTAN, the COLTAN becomes more tantalized, and both are strong when subjected to shear modulus ,electrical conductivity of COLATN also increases with increasing tantalum, but with its greater density, small cell size because of lanthanide contraction than the niobium, increasing the number of tantalum on COLTAN in cassiterite increases the quality of COLTAN in cassiterite, therefore we haveniobate type cassiterite, tantalized type cassiterite and coltan type cassiterite. In conclusion, the presence or absence of tantalum on COLTAN determines their genetic rock origin, in which the amount of tantalum on COLTAN increased from alkali rock with ∆ G ≥ 0, e.g., nephelinesyenite to more silicic, with ∆ G > 0, e.g., granite pegmatite which gives the account that cassiterite rich in niobium is less dense than the cassiterite rich in tantalum.After comparative analyses between columbite and tantalite in cassiterite, concise valuable substantive empirical novel model was developed and can be employed to study COLTAN in cassiterite. This concise empirical novel model was, “COLTAN model designed with the aid of: Matrix equation, Oxidation and the Tantalization process, and can be recommended to study the effect of tantalum on COLTAN and the application can improve mineral processing in extractive Industry.

A Review of Tungsten Resources and Potential Extraction from Mine Waste

Tungsten is recognized as a critical metal due to its unique properties, economic importance, and limited sources of supply. It has wide applications where hardness, high density, high wear, and high-temperature resistance are required, such as in mining, construction, energy generation, electronics, aerospace, and defense sectors. The two primary tungsten minerals, and the only minerals of economic importance, are wolframite and scheelite. Secondary tungsten minerals are rare and generated by hydrothermal or supergene alteration rather than by atmospheric weathering. There are no reported concerns for tungsten toxicity. However, tungsten tailings and other residues may represent severe risks to human health and the environment. Tungsten metal scrap is the only secondary source for this metal but reprocessing of tungsten tailings may also become important in the future. Enhanced gravity separation, wet high-intensity magnetic separation, and flotation have been reported to be successful in reprocessing tungsten tailings, while bioleaching can assist with removing some toxic elements. In 2020, the world’s tungsten mine production was estimated at 84 kt of tungsten (106 kt WO3), with known tungsten reserves of 3400 kt. In addition, old tungsten tailings deposits may have great potential for exploration. The incomplete statistics indicate about 96 kt of tungsten content in those deposits, with an average grade of 0.1% WO3 (versus typical grades of 0.3–1% in primary deposits). This paper aims to provide an overview of tungsten minerals, tungsten primary and secondary resources, and tungsten mine waste, including its environmental risks and potential for reprocessing.

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.

Novel separation process for obtaining recycled cement and high-quality recycled sand from waste hardened concrete

Separation is a fundamental step for concrete recycling, enabling not only the achievement of reliable and cleaner recycled aggregates but also the better re-use of the remaining concrete constituents. Recently, a new hydraulic binder produced from the hydrated cement paste contained in waste concrete, which is associated with lower processing temperatures and carbon dioxide emissions, has gained momentum in the history of concrete recycling. However, a decisive turning point for its application lies in the successful individualisation of the cement paste and aggregate initially contained in concrete debris. This paper describes a new patented method involving a mechanical comminution stage and a high-intensity magnetic separation process to obtain the cementitious fraction in concrete and retrieve cleaner fine aggregate. The efficiency of the proposed method was assessed through image analysis, thermogravimetry, X-ray diffraction and acid attack. In addition, cement pastes produced with the obtained recycled cement after thermal activation were characterised in terms of mechanical strength. Findings suggest that the proposed method effectively separated the main concrete constituents, especially when the waste material was reduced to the size range 150–500 μm. It was possible to obtain a recycled binder at the current laboratory scale with up to about 80% cement content by weight (nearly 90% in volume). Furthermore, a cleaner recycled fine aggregate, with minimal cement paste contamination, as low as less than 3 wt%, was also obtained. The mechanical strength of pastes with recycled cement retrieved from waste concrete was about 70% of that of reference pastes of equal water/binder produced with recycled cement from non-contaminated waste cement pastes.

Extraction of Manganese and Iron from a Refractory Coarse Manganese Concentrate

In this research, the coarse manganese concentrate was collected from a manganese ore concentrator in Tongren of China, and the contents of manganese and iron in coarse manganese concentrate were 28.63% and 18.65%, respectively. The majority of the minerals in coarse manganese concentrate occur in rhodochrosite, limonite, quartz, olivine, etc. Calcium chloride, calcium hypochlorite, coke, and coarse manganese concentrate were placed in a roasting furnace to conduct segregation roasting, which resulted in a partial chlorination reaction of iron to produce FeCl3, ferric chloride reduced to metallic iron and adsorbed onto the coke, and rhodochrosite broken down into manganese oxide. Iron was extracted from the roasted ore using low-intensity magnetic separation, and manganese was further extracted from the low-intensity magnetic separation tailings by high-intensity magnetic separation. The test results showed that iron concentrate with an iron grade of 78.63% and iron recovery of 83.60%, and manganese concentrate with a manganese grade of 54.04% and manganese recovery of 94.82% were obtained under the following optimal conditions: roasting temperature of 1273 K, roasting time of 60 min, calcium chloride dosage of 10%, calcium hypochlorite dosage of 5%, coke dosage of 10%, coke size of −1 mm, grinding fineness of −0.06 mm occupying 90%, low-intensity magnetic field intensity of 0.14 T, and high-intensity magnetic field intensity of 0.65 T. Most minerals in the iron concentrate were Fe, Fe3O4, and a small amount of SiO2 and CaSiO3; the main minerals in the manganese were MnO, and a small amount of Fe3O4, SiO2, and CaSiO3. The thermodynamic calculation results are in good agreement with the test results.

Technological investigations of alluvial garnet sands from the Kola Peninsula

The paper presents the investigation results on two technological samples of alluvial garnet sands from Yavr area located in the southwest of the Kola Peninsula. The first sample TP-11/2 (mass 250 kg) was used to study the granulometric, mineralogical and chemical composition of garnet sands. The second sample TP-12 (mass about 6.5 ton) was used to manufacture some garnet concentrates for the waterjet cutting testing. It has been established that the main material of TP-11/2 sample is concentrated in the size of -0.63 + 0.10 mm. The larger particles make 5.0%, the smaller particles make 7.0%. The size distribution in the TP-12 sample is similar. The main minerals of the sands are quartz, feldspar, garnet, amphiboles, pyroxenes, mica, rutile and ilmenite. The percentage of secondary minerals represented by sillimanite, kyanite, apatite, tourmaline, graphite, magnetite, and single zircon grains is less than 2%. Garnet in Javr area sands is 9–-97% in the free phase. The mass concentration of garnet in the sands is 15–19%, the mass concentration of rutile is 1.0%. Garnet corresponds to almandine in composition. A small part of garnets (about 15–20%) contains a pyrope component. The prevailing shape of garnet grains is angular; the profile of the grains is predominantly isometric and elongated. The garnet sands were dressed at the pilot concentration plant of the Mining Institute, in the gravitymagnetic-electric circuit using the following equipment: a fine screen, a spiral sluice, a concentration table, a weak field magnetic separator, a high-intensity magnetic separator, an electrostatic separator for scavenging of rough garnet concentrates. According to the test results, all garnet concentrates with the size of –0.63 + 0.315 mm, –0.315 + 0.18 mm, –0.18 + 0.10 mm were assumed suitable for the waterjet cutting.

A Combined Soda Sintering and Microwave Reductive Roasting Process of Bauxite Residue for Iron Recovery

In this study an integrated process is presented as a suitable method to transform Fe3+ oxides present in bauxite residue into magnetic oxides and metallic iron through a microwave roasting reduction, avoiding the formation of hercynite (FeAl2O4). In the first step, all the alumina phases were transformed into sodium aluminates by adding sodium carbonate as a flux to BR and then leached out through alkali-leaching to recover alumina. Subsequently, the leaching residue was mixed with carbon and roasted by using a microwave furnace at the optimum conditions. The iron oxide present in the sinter was converted into metallic iron (98%). In addition, hercynite was not detected. The produced cinder was subjected to a wet high intensity magnetic separation process to separate iron from the other elements.

Enrichment Of Low Grade Ferruginous Manganese Ore By Pilot Scale Wet High Intensity Magnetic Separation (WHIMS)

Enrichment Of Low Grade Ferruginous Manganese Ore By Pilot Scale Wet High Intensity Magnetic Separation (WHIMS)

Development of impurities removal process for low-grade Sanje iron ore using mineral processing technologies

In this study, the impurities removal process for low-grade Sanje iron ore was developed using Wet High-intensity magnetic separation (WHIMS) and Reverse flotation (RF). Sanje Iron Ore is the low-grade hematite ores found in Nampundwe area of Zambia from which Iron is to be extracted and used as the feed in the steelmaking process. The ore contains 34.18 mass per cent Iron grade, 31.10 mass% of Silica (SiO2) and 7.65 mass per cent Alumina (Al2O3). Magnetic Separation experiments were done using Series L Model 4 laboratory magnetic Separator (L-4 Machine) as the first stage impurity removal process and the effect of various magnetic separation parameters such as magnetic flux density, particle size density and pulp density of the feed were studied. The results showed that 10 T was optimal magnetic flux density which enhanced the recovery of 93 per cent of iron with 53.22 mass per cent grade. The iron concentrate produced from magnetic separation contained 12.04 massper cent Silica and 3.94 massper cent Alumna and therefore, it was further treated using Reverse flotation. In reverse flotation, various parameters such as pH, collector dosage, Iron depressant dosage and quartz activator dosage were investigated. The results showed that 81.94 per cent was recovered at the concentrate’s pH of 6.8 using 200 g/T of 0.1 per cent calcium oxide (CaO) as silica activator and one kg/T of 0.1 per cent causticised starch as Iron depressant. Sodium Oleate (NaOL) and Dodceylamine Acetate (DAA) each with discrete dosage, were used as Anionic and Cationic collectors respectively. Alumina was consequently reduced to 1.04 mass per cent and Silica to 2.04 mass per cent at optimum respective collector’s dosage of 0.250 kg/T using 0.02 kg/T of Methyl Isobutyl Carbinol (MIBC) frother. Additionally, phosphorous was also observed to be reduced from 0.05 mass per cent to 0.01 mass per cent. The designed multi-stage process involving feeding the concentrate from WHIMS into RF process therefore produced a high-grade iron concentrate iron with 67.27 mass per cent grade, 2.04 mass per cent silica, 1.04 mass per cent alumina.

Preparation and Characterisation of Zirconia Nano-materials Prepared From Zircon Minerals of Brahmagiri Coast

Zirconium oxide or zirconia is a valuable material for many applications. It is more encouraging when its particle size reduced to nanometre range. In the present paper, zircon mineral is recovered from beach placer deposits of Brahmagiri coastline of Puri District, Odisha, India, using different unit operations such as spiral concentrator, wet high-intensity magnetic separator, flotation cell and high-tension separator. Then, its value addition is done by preparation of zirconia nanoparticles through chemical route and the nano-material is also characterised. Characterisation of zirconia includes XRD, SEM/TEM, Raman spectra, etc. The photocatalytic activity of zirconia is also studied using methylene blue. It is found that zirconia behaves in an excellent way in methylene blue decolourisation and follows the first-order kinetics.

Совершенствование технологии обогащения сидеритовых руд Бакальского месторождения

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)

Study On Beneficiation Of Silica Sand By Wet High-Intensity Magnetic Separators (WHIMS) And Reverse Flotation Technique For Glass Application: A Case Study From Sihanoukville, Cambodia

White silica sand samples were collected from Steuong Hav district area. The samples were mixed and quartered to obtain a representative sample for physical and chemical characterization. Silica (SiO2) and iron oxide (Fe2O3) content were measured by X-ray fluorescence (XRF) analysis. The results showed silica and iron oxide content at 94.83 wt.% and 0.189 wt.% representatively. In this study, a shaking table, Wet High-Intensity Magnetic Separators (WHIMS), and reverse flotation technique was undertaken to remove mainly iron oxide. The collectors amine (named AOA) and petroleum supinate (named NANZA), pine oil as frother, and H2SO4 as depressant were used to optimize the froth performance. The iron oxide content was removed from 0.189wt.% to 0.062 wt.% and the silica content was upgraded from 94.83 wt.% to 98.6 wt.% after the process.

Rare-earth metal ore processing technologies when developing new deposits

The article provides a brief overview of processing technologies for rare-earth raw materials used under greenfield development projects in different countries of the world (Africa, Greenland, Australia, Canada). The projects feature deposits with different mineral compositions, mass fractions of rare-earth metals (REM) in ores of 0.2 to 15 %, and the presence of niobium, zirconium, tantalum, phosphorus, uranium, and thorium. The resulting production facilities will extract 180 kt to 7.2 Mt rare-earth ore annually to generate 1.5 to 20 kt oxides of heavy and light groups of rare-earth metals along with the rare metals. The analysis of technologies for the projects considered demonstrates that magnetic and radiometric separation, dense-medium concentration and flotation with hydrometallurgical processing in the form of leaching with sulfuric or hydrochloric acid, followed by extraction of the target products, will be used for the processing of rare-earth raw materials. A characteristic feature of a number of projects is, first of all, the direct hydrometallurgical processing of the feed. The concentration technologies for ores containing rare-earth metals also indicate a clear trend towards a more active use of high-intensity magnetic separation. The main products to be obtained with these technologies will include composite concentrates of oxides or carbonates of rare-earth metals. At the same time, the commissioning dates for the projects are being repeatedly postponed; the implementation of many projects remains uncertain, which is largely due to the stagnant dynamics of global prices for rare-earth metals.

Recovery of Iron values through conventional beneficiation techniques from Banded Hematite Jasper of Eastern India with special reference to mineralogical and chemical characterization

Background/Objectives: Due to soaring demand and rapid depletion of high-grade iron ores, lean grade iron ores of India like BHJ and BHQ needs to be utilized through suitable beneficiation techniques. Methods: Banded Hematite Jasper (BHJ) sample of Bonai-Keonjhar belt (BK belt), Odisha, India assayed 35.3 % Fe, 47.1% SiO2 and 0.96% Al2O3 was investigated in respect of mineralogy, liberation characteristics and chemistry to finding out its optimum beneficiation potential. In the present investigation, efforts have been made to characterize the BHJ sample with reference to its beneficiation response. The sample was subjected to various beneficiation operations like Jigging followed by hydrocyclone, two-stage tabling and magnetic Separation. Findings: Mineralogical studies indicate that quartz and hematite are the major mineral phases, whereas goethite, martitized magnetite and clay (kaolinite) are present in very minor amounts. The liberation characteristic indicates that the average band thickness of Iron bearing mineral is of 1680 microns and 80% of the iron bearing minerals are liberated at -105 microns size. The two stage tabling of jig concentrate with desliming gives better outcome as compared with direct tabling of jig concentrate. An iron ore concentrate assayed 64.5% Fe, 5.6% SiO2 and 0.80% Al2O3 with wt% recovery of 23.2% can be obtained from two stage tabling. Another concentrate from magnetic separation of table middling and hydrocyclone assayed 63.2% Fe, 7.2% SiO2 and 0.7% Al2O3 with wt% recovery of 12.4% can be obtained. Novelty/ Application: Here a conventional beneficiation flow sheet is developed with a finding that, in order to beneficiate ore like banded hematite jasper (BHJ), an integral characterization approach is very much essential. Both of the concentrates obtained through the flow sheet assayed 64% Fe, 6.2% SiO2 and 0.7% Al2O3 with a wt% recovery of 35.6% can be utilized as a feed stock for pellet making in iron ore industries. Keywords: Banded Hematite Jasper (BHJ); mineral beneficiation; wet high intensity magnetic separator (WHIMS); jigging; Bonai-Keonjhar belt

As sorption onto Fe-based nanoparticles and recovery from soils by means of wet high intensity magnetic separation

In this work, we studied the soil washing of an As-polluted soil utilizing Wet High Intensity Magnetic Separation (WHIMS) after pre-treatment with nanoparticles. First, Fe-Ni nanoparticles of high saturation magnetization and appropriate size were synthesized. Soil samples were then pre-treated with a dose of nanoparticles before undergoing magnetic separation at different field intensities. Two nanoparticles doses were used and, in addition, control trials with un-pre-treated soil were also performed. Nickel concentration, and magnetic properties served to evaluate the underlying physical behavior of the nanoparticles subjected to magnetic separation. Additionally, leaching tests and As speciation was performed to evaluate As immobilization due to sorption onto the nanoparticles. For the interpretation of the chemical separation results we propose a novel efficiency index, considering both As concentration and weight recoveries. Results show that separation efficiency after nanoparticles pre-treatment yielded better results for lower separation voltages than no pre-treatment, indicating that nanoparticles reported to the magnetic fraction with the As adsorbed onto them. In contrast, at higher separation voltages, more paramagnetic materials reported to the magnetic fraction, thus hindering As separation. Besides, As immobilization was also observed in the nanoparticles pre-treated samples. Accordingly, we obtained a combined soil treatment approach, involving both, the reduction of the volume of polluted soil (physical soil washing) and its stabilization.

Up-Concentration of Chromium in Stainless Steel Slag and Ferrochromium Slags by Magnetic and Gravity Separation

Slags coming from stainless steel (SS) and ferrochromium (FeCr) production generally contain between 1 and 10% Cr, mostly present in entrapped metallic particles (Fe–Cr alloys) and in spinel structures. To recover Cr from these slags, magnetic and gravity separation techniques were tested for up-concentrating Cr in a fraction for further processing. In case of SS slag and low carbon (LC) FeCr slag a wet high intensity magnetic separation can up-concentrate Cr in the SS slag (fraction <150 µm) from 2.3 wt.% to almost 9 wt.% with a yield of 7 wt.%, and in the LC FeCr slag from 3.1 wt.% to 11 wt.% with a yield of 3 wt.%. Different behavior of Cr-containing spinel’s in the two slag types observed during magnetic separation can be explained by the presence or absence of Fe in the lattice of the Cr-containing spinel’s, which affects their magnetic susceptibility. The Cr content of the concentrates is low compared to chromium ores, indicating that additional processing steps are necessary for a recovery process. In the case of high carbon (HC) FeCr slag, a Cr up-concentration by a factor of more than three (from 9 wt.% to 28 wt.%) can be achieved on the as received slag, after a single dry low intensity magnetic separation step, due to the well-liberated Cr-rich compounds present in this slag. After gravity separation of the HC FeCr slag, a fraction with a Cr content close to high grade Cr ores (≥50% Cr2O3) can be obtained. This fraction represents 12 wt.% of the HC FeCr slag, and can probably be used directly in traditional smelting processes.

Characterization of the Angico dos Dias alkaline-carbonatite complex for phosphate rock processing

The alkaline-carbonatite complex of Angico dos Dias, located in the Northeast of Brazil, is currently exploited to produce phosphate rock concentrate. Coarse particles (above 600 µm) are processed through a dry route accounting for 53% of the run of mine. Chemical and mineralogical compositions, density, particle size distribution, mineralogical associations, and mineral liberation were determined. A wet processing route for the fine particles was proposed in this paper, comprehending the following stages: scrubbing, low-intensity magnetic separation, desliming, milling, anionic direct flotation, and wet high-intensity magnetic separation. X-ray diffraction analysis showed fluorapatite as the main phosphate bearing mineral, silicates and iron oxyhydroxides are the predominantly gangue minerals. Mineral liberation analysis showed that 40.8% of the apatite particles had completely exposed surface and 73.05% had at least 90%. Regarding mineral liberation, 87.6% were entirely liberated and 11.6% were binary association. Energy dispersive spectrum microanalysis results showed the presence of three rare earth elements bearing minerals in the ore. The average P2O5 content of the ROM ore was 15.39%, and its recovery above 212 µm was 76.95%. Below this size, the P2O5 content decrease progressively, whereas the Fe2O3, Al2O3, and SiO2 contaminants increase. The absence of calcite and dolomite could favor the process selectivity in an anionic direct flotation using fatty acids as collectors. Therefore, the proposal for a wet processing design for concentration of apatite covers.

Processing of Low-Grade Chromite Ore for Ferroalloy Production: A Case Study from Ghutrigaon, Odisha, India

The low-grade siliceous chromite ore from Ghutrigaon, Odisha, India, containing ~ 16% Cr2O3, with Cr/Fe ratio of 1.97 and ~ 55% of SiO2, does not find any use in metallurgical industry and hence considered as waste. Mineralogical investigation indicates the presence of chromite and quartz as major minerals with minor fuchsite and kaolinite. The beneficiation studies reveal that the product can be enriched to a Cr/Fe ratio of 3.35 and 3.02 by gravity concentration (wet shaking table) and wet high intensity magnetic separation, respectively. Tiny Cr-grains within quartz and fine silica dusts within chromite inhibit liberation of chromite resulting in poor response to physical beneficiation. As an alternative, processing of ore through pyro-metallurgical route was evaluated. Chromite fines mixed with carbon and lime in the form of pellets/granules was charged to a plasma reactor. In about ten minutes, the metal globules/prills were separated from the slag in 1:6 ratio. The metal, examined through XRD and optical microscope, was found to be ferrochrome alloy. In situ EDAX analysis indicated the metal to have 61.51% Cr, 26.52% Fe and 13.1% C with minor silica (2.42%), and the slag was composed of Ca2Al2SiO7 which revealed that both metal and slag so obtained could suitably be used in different industries.