Wet Magnetic Separation Research Articles

Investigation of the effect of mineral composition and size on particle separation in Wet low and high intensities magnetic separators: An industrial case

Magnetic separation is used in ore processing to separate the minerals according to their magnetic susceptibility. Particle size also plays a role in the separation although few industrial results are presented in the literature to discuss this matter. Results from sampling industrial Wet Low Intensity Magnetic Separators (WLIMS) and Wet High Intensity Magnetic Separators (WHIMS) for processing an iron ore show that except for the strongly paramagnetic magnetite (Fe3O4), the recovery of minerals decreases with increasing particle size for both WLIMS and WHIMS. The examination of polished sections of the coarse size fractions from the reject streams of the WHIMS does not provide ground to suspect liberation to be responsible for the reduced recovery of coarse particles. Results also show that it is difficult to establish clear relationships between the mineral recoveries and their reported magnetic susceptibilities for WLIMS while for WHIMS a weak trend is observable.

Judicious combinations of gravity, magnetic, electrostatic separators and microwave heat energy on recovery of ilmenite from Humma lean grade beach placer deposit

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.

Integration of experimental study and neural network modeling for estimating iron recovery in Davis tube tests

Magnetic separation is a common procedure for the enrichment of magnetic iron ores. Davis tube (DT) test is a standard laboratory technique used to determine the optimum magnetic recovery of iron ore using wet low-intensity magnetic separators. However, the DT test is time-consuming and labour-intensive. In this study, based on the results of DT-tests, generalized regression (GRNN) and radial basis function (RBF) neural networks were developed to predict iron recovery through the Fe and FeO content of the feed. First, the DT tests were performed on 613 iron ore samples with varying Fe and FeO content. Then, neural networks were used to model the iron recovery from the DT test, using the Fe and FeO content of the feed as input data. The modeling results showed that GRNN is a better model for predicting iron recovery. The main statistical metrics indicated that GRNN has AAPRE, RMSE, and R2 values of 3.929%, 2.804, and 0.976 respectively for a total of 613 data points. Moreover, sensitivity analysis demonstrated that iron recovery is directly influenced by both Fe and FeO contents, with FeO content having a more pronounced effect. Finally, Leverage analysis showed that GRNN is highly reliable for predicting iron recovery, with only 2.77% of data points flagged as suspicious based on outlier estimation.

Pyrometallurgical processing of manganese ore

Manganese ore contains valuable oxides, such as manganese oxide (MnO2/Mn2O3/Mn3O4), iron oxide (Fe2O3) and silica (SiO2). In the present study, an attempt has been made to separate these oxides through pyrometallurgical processing routes for the extraction of ferromanganese and silicomanganese. Lean manganese ores were subjected to ball milling followed by carbothermic reduction at a temperature of 1200 °C for 2 h. The reduced ores were then subjected to wet magnetic separation to obtain the magnetic constituents in the reduced ores. It was observed that it is not possible to remove the silica content from the ore. It appeared that the reduced sample had oxides of iron, silicon and manganese after its wet magnetic separation. The magnetic constituents were subjected to metallothermic reduction through pure aluminium powders to recover valuable metals/alloys.

Recovery of ferronickel by green selective reduction of nickel laterite

Abstract The conversion of nickel laterite into ferronickel is commonly done through a high-temperature pyrometallurgical process that utilizes fossil fuels, which leads to environmental emissions. In order to deal with this, a biomass-based selective reduction process is proposed that uses palm shell charcoal (PSC) as the reductant. In this study, we investigate how to selectively reduce saprolytic nickel ore in various conditions, including pelletization, reduction at 1150°C for one hour, and wet magnetic separation. The optimal conditions, determined with 0.3 stoichiometric carbon, yielded a nickel content and recovery of 22.778 wt.% and 27.541 wt.%, respectively. Phases identified in the reduced pellet include forsterite, diopside, ferronickel, troilite, and olivine. Adjusting stoichiometry influences nickel concentration, resulting in increased recovery; however, excessive stoichiometry intensifies iron metallization, reducing nickel content. The addition of sodium sulfate affects nickel and iron recovery by promoting FeS phase formation, resulting in reduced iron recovery.

Iron recovery from bauxite residue (BR) through magnetic separation; Effect of endogenous properties and processing conditions

Bauxite residue (BR) is major by-product of the Bayer process for aluminium production, and its accumulation confers environmental risk due to its high alkalinity and fineness. The high Fe content and the BR abundance render it an attractive secondary source of iron, with magnetic separation being the preferable beneficiation technique applied for quality upgrade.In this study, the recovery of Fe-rich concentrate was investigated, using Wet High Intensity Magnetic Separator (WHIMS) under weak magnetic induction ranging between 70 and 2000 Gs. Aiming to enhance the susceptibility of ferrous phase, a hydrothermal treatment of BR was applied under alkaline conditions in the presence of Fe2+ towards the reduction of antiferromagnetic hematite forming ferromagnetic magnetite of considerable magnetic susceptibility compared to the former ferrous phase. Under processing time of 3 h at 250 °C, the hematite conversion degree and Al dissolution reached ≃ approx. 50 % and 72 %, respectively. As for material conditioning prior to magnetic separation, sole agitation, and agitation in combination with ultrasounds were tested aiming the homogeneous dispersion of particles.After hydrothermal treatment, Fe grade increased by 7.7 % (from 35 to 42.7 wt%), while combined use of agitation and ultrasounds increased Fe grade but decreased recovery. The extended investigation of BR granulometry and minerals liberation revealed that the efficiency of the magnetic separation is radically hindered by these endogenous characteristics.

Separation and extraction of iron resources from hazardous electric arc furnace (EAF) steel slag: Aggregation of Fe-rich layers, magnetic separation, powder characterization

China's electric arc furnace (EAF) slag reserves are huge, the problems of EAF slag resource application need to be solved urgently. In this study, high temperature holding and slow cooling treatment were used to treat the slag. The phase and structure of the slag were analysed by means of X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. To analyse the migration pattern of iron elements and to study the interaction between EAF slag basicity and magnetic separation efficiency. The results show that, there is an obvious layering phenomenon during the cooling slag, and the top layer is the Fe-rich layer. The slow cooling treatment makes the Fe-rich phase grow sufficiently and improves the dissociation efficiency of the Fe-rich phase in the crushing process. As the basicity increases, the thickness of the iron-rich layer gradually decreases and the iron element is transferred to the RO phase, while the concentrate yield decreases. Multi-stage wet weak magnetic separation of treatment slag resulted in the highest concentrate yield of 49.05 % at an basicity of 1, with a T.Fe content of 56.711 %, and 70.32 % of the iron component entering the concentrate. The concentrate can be returned to the steelmaking process instead of the charge, and the tailings can be used to make high value-added products.

Nickel recovery in ferronickel concentrate by green selective reduction of nickel laterite

Nickel laterite is typically processed into ferronickel through a pyrometallurgical method involving high temperatures and the use of fossil fuels, such as coals or cokes. Unfortunately, this process releases emissions like CO2, SO2, and NOx into the environment. This study explores a sustainable approach for nickel laterite processing by investigating low-temperature selective reduction using various biomass reductants. The materials, including saprolitic nickel ore and biomass types (palm kernel shell charcoal or PSC, lamtoro wood charcoal, coconut shell charcoal, and rubber wood charcoal), undergo pelletization, selective reduction at 1150 °C, and wet magnetic separation. PSC biomass is superior to other biomass due to its 217.2 m2/g specific surface area value. Optimal conditions were achieved using 0.3 stoichiometric PSC, along with the addition of 10 wt% of sodium sulfate as an additive. This has led to a nickel mass fraction of 26.0 wt% and a recovery rate of 27.4 %.

Possibility of using wet magnetic separation for pre-enrichment of finely crushed magnetite ore

Possibility of using wet magnetic separation for pre-enrichment of finely crushed magnetite ore

Zero-valent iron (ZVI) facilitated in-situ selenium (Se) immobilization and its recovery by magnetic separation: Mechanisms and implications for microbial ecology

Selenium (Se(VI)) is environmentally toxic. One of the most popular reducing agents for Se(VI) remediation is zero-valent iron (ZVI). However, most ZVI studies were carried out in water matrices, and the recovery of reduced Se has not been investigated. A water-sediment system constructed using natural sediment was employed here to study in-situ Se remediation and recovery. A combined effect of ZVI and unacclimated microorganisms from natural sediment was found in Se(VI) removal in the water phase with a removal efficiency of 92.7 ± 1.1% within 7 d when 10 mg L−1 Se(VI) was present. Soluble Se(VI) was removed from the water and precipitated to the sediment phase (74.8 ± 0.1%), which was enhanced by the addition of ZVI (83.3 ± 0.3%). The recovery proportion of the immobilized Se was 34.2 ± 0.1% and 92.5 ± 0.2% through wet and dry magnetic separation with 1 g L−1 ZVI added, respectively. The 16 s rRNA sequencing revealed the variations in the microbial communities in response to ZVI and Se, which the magnetic separation could potentially mitigate in the long term. This study provides a novel technique to achieve in-situ Se remediation and recovery by combining ZVI reduction and magnetic separation.

The Waelz Slag from Electric Arc Furnace Dust Processing: Characterization and Magnetic Separation Studies.

The Waelz slag generated during electric arc furnace dust processing is an iron-rich product with significant amounts of iron, zinc and copper. About 600-800 kg of the Waelz slag is generated per ton of the dust processed. The Waelz slag samples from two different plants were thoroughly characterized using inductively coupled plasma optical emission spectroscopy (ICP-AES), X-ray diffraction analysis (XRD), chemical phase analysis, Mössbauer spectroscopy and other supporting methods. The phase distribution of iron, zinc and copper was determined in the Waelz slag samples. Low-intensity wet magnetic separation was tested for the iron recovery from the Waelz slag samples. It was found that the Waelz slag samples have complex chemical and mineralogical compositions, which can impede the selective recovery of valuable elements. The obtained results indicate that the chemical and mineralogical composition of the Waelz slag samples has a considerable effect on the magnetic separation indexes. The experiments showed that the iron concentrates with Fe contents of 73% and 46.8% with the metallization degrees of 87.2% and 57.5% and the iron recovery degree of 54.8% and 52.9% were obtained at optimal conditions for two different samples, respectively, without selective segregation of Cu and Zn in the magnetic or non-magnetic fraction.

Evaluasi Kinerja Alat Pengolahan Wet Belt Low Intensity Magnetic Separator (WBLIMS) Untuk Meningkatkan Kadar dan Recovery Sn di TB Primer Batubesi PT Timah Tbk Kabupaten Belitung Timur

Primary TB Batubesi Site a subsidiary of PT Timah Tbk, processes primary tin feed stockpile and SHP of oxide clay type using various tools, including the Wet Belt Low Intensity Magnetic Separator (WBLIMS). Currently, WBLIMS can only produce tin concentrate with a grade of 0.5-2% and a recovery of 5-8%, falling below the company's target of 8% grade and 15% recovery (XRF Test). This research conducted eight experiments with variations in feed types and rates. The WBLIMS feed from the stockpile has a Sn content of 0.62%, resulting in a tin concentrate with 1.21% Sn and a recovery of 7.05%. On the other hand, the feed from SHP has a Sn content of 0.61%, resulting in a tin concentrate with 0.95% Sn and a recovery of 5.11%. The type and rate of feed affect the increase in Sn grade and recovery. At low feed rates, the feed material yields lower Sn grade and recovery, while at high feed rates, the results are higher. Increasing the feed rate for WBLIMS from the stockpile leads to a decrease in Sn grade and recovery, whereas in the processing of SHP, the Sn grade increases but recovery varies. Experiments F1L1 and F2L3 yield the most optimal Sn grade and recovery, with F1L1 having a Sn grade of 2.28% and recovery of 11.54%, and F2L3 having a Sn grade of 2.87% and recovery of 9.24%. Although not reaching the company's target, these experimental results can enhance the Sn grade and recovery compared to the previous setup.

Nickel recovery in tailling from the Chromite beneficiation process in Mau Lam, Thanh Hoa by the reduction roasting-magnetic separation process

In Thanh Hoa province, large chromite ore deposits were discovered. These types of ores also contain significant quantity of nickel metal, with total nickel reserves estimated to be over three million tones. According to the practices of mining and beneficiation of these chromite ores, nickel is discarded in the waste dumps as a non-valuable metal and has not been recovered ever. Through many years of mining and processing of chromite ores, large dumps are formed to such huge volumes that can be considered as a significantly secondary resource of valuable nickel metal. Nickel exists in the form of laterite ores so that it is difficult to be recovered. Currently, there is no commercial technology available for recovery of nickel or other valuable metals from this type of raw material sources. This article presents some research results on applying the reduction calcination – magnetic separation process for recovery of nickel. In particular, some important reduction operating variables such as temperature, calcination time, fuel coal ratio, and Na2SO4 additive were investigated. From the tailing samples of the Mau Lam – Thanh Hoa chromite beneficiation process, important optimal reducing conditions have been determined including 1,1000C of reduction temperature, 8% of anthracite coal, 8% of Na2SO4 additive, and the reduction time of 90 minutes. The reduced product was finely grounded and separated at a magnetic field of 0.3T using the wet magnetic separator. At optimal operating variables, the nickel content of the final nickel concentrate was 4.02% Ni and the overall nickel recovery was 91.2%. The positive results necessarily lead to a need to continue researching the possibility of practical application to recover nickel and thus contribute to the rational utilization of mineral resources of the country.

Chemical and mineralogical characterization to define parameters for comminution, aiming at granulometric adequacy in rock rich in feldspars extracted in Pedra Lavrada-PB

The demand for high purity feldspars with low contaminant content, especially for use in the manufacture of porcelain tiles and white crockery, poses a challenge for processing the ore. Due to the need for very low iron levels, less than 0.15%, operations must be more complex, costly and capable of providing a high purity final product. To this end, it is necessary to employ mineralogical and technological characterization to understand the ore and plan the operations of the processing plant. A sample of rock rich in feldspars collected in an extraction in the municipality of Pedra Lavrada/PB was studied, aiming to identify the chemical composition and release spectrum using XRD and SEM techniques. Aliquots were subjected to preparation, granulometric classification and high-intensity wet magnetic separation steps. The results indicate that the rock has high concentrations of feldspars, quartz and a significant content of magnetite and hornblende. The physical release of magnetic mineral phases occurs below 0.104mm, and fragmentation operations must be designed with this grain size standard in mind. Magnetic separation, with mass recovery of 14.01% in relation to the feed, satisfactorily guaranteed a reduction in the concentration of magnetic minerals in the ore

Enrichment of Iron-containing Concentrate with Ammonium Hydrofluoride

The rationality of using ash and slag waste from coal-fired TPP to obtain high-quality iron-containing concentrate (FC) is demonstrated. Using the method of wet magnetic separation of ash and slag waste from TPP, FC is extracted with Fe2O3 content of 59.2 %. It has been established that the method of chemical enrichment with ammonium hydrofluoride can increase the Fe2O3 content in FC to 79 %; a by-product of the reaction between FC and NH4F•HF is high-quality amorphous silica (white soot). The effect of process temperature on the composition of the resulting FC has been studied, at that the phase composition of iron oxides remains virtually unchanged. Optimal modes of the process are proposed.

A novel magnetic geopolymer-based adsorbent prepared from heated glauconite and separated magnetite: Experiments and statistical physics treatment for crystal violet

Sinai copper ore with 9.48 % of Fe2O3 was treated using a laboratory-scale mineral processing techniques that included size reduction (below 75 µm) and a wet low intensity drum-type magnetic separation. After this treatment method, the separated magnetite product containing about 85 % of Fe2O3 was extracted. A mixture of heated glauconite (900 °C/2h) and the extracted magnetite was activated by sodium silicate (Na2SiO3) to obtain a novel glauconite-based magnetic geopolymer (namely GMG). Several analytical techniques (i.e., XRD, XRF, FESEM, FTIR, EDX, TEM, elemental mapping, and zeta potential) were used in the characterization of GMG and its performance for crystal violet (CRV) remediation was studied. The equilibrium data at pH 8.0 and 25 – 50 °C were fitted to a statistical physics multilayer model and classical isotherm equations to understand the CRV adsorption mechanism. The theoretical calculations indicated that GMG can adsorb 1.12 to 1.39 of CRV molecules per functional group (n), suggesting the presence of a multi-interaction mechanism and vertical adsorption orientation on GMG surface. For this basic dye, the estimated saturation adsorption capacities (Qsat) ranged from 684 to 612 mg/g, and an exothermic binding interaction was associated with the removal of this dye molecule. The adsorption energies (ΔE) ranged between 15.05 and 36.74 kJ/mol, indicating that physical forces, such as electrostatic interactions and hydrogen bonds, governed the GMG-CRV interactions. After fourth adsorption–desorption cycles, the regenerated GMG showed 74 % of its adsorption capacities, which suggested the suitability of this adsorbent to be regenerated and reused multiple times in water treatment. Overall, the combination between the separated magnetite and glauconite was an effective approach for the remediation of effluents that contain dye molecules

МІНЕРАЛЬНІ ТА ФІЗИКО-ХІМІЧНІ ЗМІНИ МАГНЕТИТОВИХ КВАРЦИТІВ ВАЛЯВКИНСЬКОГО ТА НОВОКРИВОРІЗЬКОГО РОДОВИЩ КРИВБАСУ В ПРОЦЕСАХ ЇХ ПЕРЕРОБКИ

Background. In order to study the mineral physical and chemical changes that occur with iron ore (magnetite quartzites) of the Valyavkinsky and Novokrivorizky deposits of the Kryvorizka iron ore basin during the mining and processing of ore at the mining and processing plant "ArcelorMittal Kryvyi Rih", the entire technological chain of mining and mineral processing was analyzed: magnetite quartzite (ore) in naturaldeposits → ore after explosion → ore after crushing at crushing plants → intermediate magnetic products and tailings of all stages of beneficiation → final magnetite concentrate. Methods. Laboratory and analytical studies, which include mineragraphic, petrographic, electron microscopic studies of iron ore, X-ray fluorescence method and atomic emission spectral analysis (determination of the content of macro- and microelements in the original ore, magnetic concentrate and tailings), X-ray diffraction analysis, microprobe analysis of magnetic concentrate and tailings, thermogravimetric analysis, chromatographic method (determination of the specific surface of a substance), sedimentation analysis, measurement of magnetic characteristics, etc. were used. Results. It was established that at the first stage of mining production (drilling and blasting, ore crushing in the quarry and at the crushing plant) there are no significant changes in minerals. At the next stage of deep processing and concentration of minerals at the ore beneficiation plant, during which the ore undergoes 3 stages of crushing, classification, desliming, and wet magnetic separation, two completely new products are formed – magnetite concentrate and tailings, which are fundamentally different from the original ore – both at the rock level and at the mineral one. Сonclusions. It was substantiated that in the process of enrichment of magnetite quartzites, the structural and textural characteristics, mineral and chemical composition, state of aggregation of the iron ore, structural and crystallochemical properties of the main ore mineral magnetite change significantly.

Evaluating the efficiency of metallized siderite concentrate electric melting

The Bakal siderites belong to poor, hard-to-enrich carbonate iron ores. The low content of phosphorus and non-ferrous metals makes siderites a valuable raw material for obtaining highly metallized concentrate suitable for use in steelmaking processes. Reduction of siderites in a rotating furnace at 1300 – 1350 °C followed by magnetic separation of waste rock allows to obtain a concentrate with metallization degree over 90 % and a content of waste rock of about 5 % suitable for steelmaking as raw materials. The purpose of this work is to evaluate the efficiency of the process aimed at obtaining metal from siderite ore including obtaining of highly metallized siderite concentrate in a recovery furnace, as well as its hot loading into ore-thermal furnace and melting process itself. To do this, the electric melting was calculated in the electric ore melting furnace providing for determination of a large number of parameters including the electricity consumption required for melting. As raw materials we used a highly metallized siderite concentrate (φmet = 92.3 %) containing 35 % of waste rock and, for comparison, a briquetted metallized siderite concentrate obtained from a lump concentrate in which a significant amount of waste rock was removed by wet magnetic separation. The results analysis shows that increase in concentrate temperatures from 25 to 1000 °C decreases specific energy consumption and at the same time increases the furnace productivity to values comparable to the parameters of melting briquetted concentrate. This confirms the efficiency of the developed process. To reduce the melting point of high-magnesium slag, it is proposed to use colemanite as flux.

STUDY OF FINE-GRAINED FIBER CONCRETE CRACKING RESISTANCE FROM THE POINT OF VIEW OF DESTRUCTION MECHANICS

Fiber reinforced concrete began to appear in the market in the 60s of the last century, and since then the interest in this type of reinforcement has been steadily growing. The article presents the results of studies on the crack resistance of concrete reinforced with polypropylene fibers of various lengths and volume concentrations in fine-grained concrete. Waste from the wet magnetic separation of the Poltava mining and concentration plant was used as an aggregate in the concrete. Polypropylene fibers with the various lengths diameter of 0.2 mm were used for reinforcement. The influence of the length and volume concentration of fibers on the crack resistance of the same strength concrete of was studied. The study results indicate that the increase in the length and volume concentration of fibers, within the limits of the experiment, significantly affects the crack resistance of fine-grained concrete.

Particle-based characterization and process modeling to comprehend the behavior of iron ores in drum-type wet low-intensity magnetic separation

Drum-type wet low-intensity magnetic separation is a versatile technique traditionally implemented in the mining industry since the mid-19th century. Yet, comprehending the process from a fundamental point of view remains challenging and its implementation still relies on “rules of thumb” that commonly disregard the ore properties and the effects of the operating conditions. This work describes an approach that combines comprehensive particle-based characterization and process modeling to integrate particle properties and equipment characteristics to describe the behavior of an iron ore in a laboratory-scale drum-type magnetic separator. Such a proposal is based on (1) laboratory testing, (2) automated mineralogy for particle-scale ore characterization, and (3) process modeling to compute the particle separation kinetics as a function of the ore intrinsic attributes and the physical principles involved in magnetic separation. This approach proposes the guidelines to obtain early information on the iron ore processing behavior, which represents a promising tool for decision-making at different stages of the beneficiation chain.