Application of hydrogen magnetizing roasting for production of commercial concentrate from low-grade hematite ore

Low-carbon production of iron and steel: Technology options, economic assessment, and policy

Thermally assisted magnetic separation and characterization studies of a low-grade hematite ore

Beneficiation of a low-grade iron ore was investigated by combination of the low-intensity magnetic separation and reverse flotation methods. The main constituents of the representative sample were 36.86% Fe, 8.1% FeO, 14.2% CaO, 13.6% SiO2, and 0.12% S based on the X-ray fluorescence, titration, and Leco analysis methods. The mineralogical studies by the X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, electron probe micro-analyzer, and Fe/FeO titration methods showed that the ore minerals present in the representative sample were magnetite, hematite, and goethite, and the main gangue minerals were calcite and quartz. The effects of the operating parameters including the feed size, solid content, and drum rotation speed were investigated on the performance of the wet low-intensity magnetic separation (WLIMS). The optimum operating conditions of WLIMS were determined to be feed size = 135 μm, solid content = 40%, and drum rotation speed = 50 rpm. Under these conditions, a concentrate of 62.69% Fe grade and 55.99% recovery was produced. The tailing of WLIMS with an iron grade of 28.75% was upgraded by reverse flotation with fatty acids as the collector. The effects of five parameters on two levels were investigated using the 25-1 fractional factorial design in 16 experiments. The optimum flotation conditions were determined to be pH = 12; dosage of collector, 1 kg/t; dosage of Ca2+ as activator, 4 kg/t; and dosage of starch as depressant, 1 kg/t. Under these conditions, a concentrate of 53.4% Fe grade and 79.91% recovery was produced.

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.

Recovery and grade are the two crucial performance parameters commonly used in mineral processing plant operations. These two parameters are interdependent. An increase in recovery would result in a decreased product grade and vice versa. The present study enumerates concentration efficiency (CE),which can be adopted exclusively for processing low-grade hematite ore by WHIMS—the reverse flotation route to produce a pellet grade concentrate. In this study, the ore’s amenability by wet high-intensity magnetic separation followed by the reverse flotation of a magnetic concentrate route is investigated on BHQ samples of the Sandur schist belt (Kumaraswamy hills), India, after its characterization by microscopic and XRD studies. Dodecyl amine acetate was used as a collector to float siliceous gangue while depressing hematite using the freshly synthesized caustic starch as a depressant. The separation efficiency of the flotation was evaluated by estimating the grade, recovery, and concentration efficiency. The WHIMS conducted using the feed with the particle size minus 106 µm (d80 = 82 µm) followed by reverse flotation produced a pellet grade concentrate assaying 64.60% Fe, a 0.32 alumina-to-silica ratio with 60.4% Fe recovery, and a yield of 37.4% with 79.0% concentration separation efficiency.

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.

The fragmentation mechanism of low-grade hematite ore in a high pressure grinding roll (HPGR) was studied based on the characteristics of comminuted products at different specific pressure levels. The major properties included the reduction ratio, liberation, specific surface energy, and specific surface area. The results showed that the fracture of low-grade hematite ore in HPGR was an interactive dynamic process in which the interaction between coarse particles of gangue minerals and fine particles of valuable minerals was alternately continuous with increased compactness and compacting strength of materials. Within a range of 2.8–4.4 N/mm2, valuable minerals were crushed after preferentially absorbing energy, whereas gangue minerals were not completely crushed and only acted as an energy transfer medium. Within a range of 4.4–5.2 N/mm2, gangue minerals were adequately crushed after absorbing the remaining energy, whereas preferentially crushed valuable minerals acted as an energy transfer medium. Within a range of 5.2–6.0 N/mm2 range, the low-grade hematite ore was not further comminuted because of the “size effect” on the strength of materials, and the comminution effect of materials became stable.

In order to increase the quality of feldspar ore and to obtain sellable feldspar concentrate, it is necessary to remove coloring impurities such as iron and titanium contained in it. For the removal of coloring minerals from feldspar ore the most widely used method is reverse flotation method. Reverse flotation process is generally carried out in conventional mechanical cells. In this study, it was aimed to enrich low-grade feldspar by using cyclojet flotation cell which was developed as an alternative to conventional cell. Then, experiments were performed by using conventional cell and wet magnetic separator and the results were compared with the flotation results obtained by using cyclojet cell. In experimental studies, 200 micrometer grain sized feldspar (albite) ore obtained from Mugla province at the west side of Turkey was used. It was detected that the sample was containing 0.100% Fe2O3 and 0.360% TiO2 as coloring minerals. Cyclojet cell, conventional cell and magnetic separator reduced the Fe2O3 content down to 0.010%, but TiO2 content was different in the concentrates obtained by different devices. There was almost no reduction in TiO2 content by magnetic separation method. Cyclojet cell reduced TiO2 content down to 0.030% and mechanical cell reduced TiO2 content down to 0.020%. The weights of the concentrate were detected as the highest (92.70%) in magnetic separator and as the lowest (75.40%) in cyclojet cell. Therefore, it is possible to say that cyclojet cell can compete with mechanical cell and removal of TiO2 in cyclojet cell is much better than the removal of TiO2 in magnetic separator. Generally, in the flotation process performed by using a reagent of Aero801 and Aero825 mixture in natural pH medium, both Fe2O3 and TiO2 can be removed at a rate of up to 90%, but magnetic separator can only remove Fe2O3 mineral.

In this paper, the removal processes for silicon (Si), aluminum (Al) and phosphorus (P) impurities from low-grade iron ore, in which hematite (Fe2O3), goethite (FeO(OH)), and quartz (SiO2) are the main mineral constituents, have been presented. The reverse froth flotation process was applied to remove silicon and aluminum impurities from the iron ore using dodecyltrimethylammonium bromide (DTAB) and dodecylamine acetate (DAA) cationic collectors at a broad slurry pH ranging from 2 to 12. Whereas alkaline roasting followed by a water washing process was employed to remove phosphorus impurity from the iron ore under the various sodium hydroxide concentrations, different roasting temperatures, and prolonged varying times. Results showed that the maximum removal rate of SiO2 and Al2O3 achieved were 58.3% and 31.0% via reverse froth flotation using DTAB collector at pH 12, whereas 38.7% SiO2 and 10.0% Al2O3 with DAA collector. The level of total (SiO2+Al2O3) impurities in the tailing as iron ore product from the reverse flotation was reduced from 7.4 mass% to 4.4 mass% as the initial level. On the other hand, about 61% of phosphorus in the iron ore was removed by the combined alkaline roasting and water washing at the conditions optimized as 50 g/kg-ore NaOH at 300°C for 0.5 h. The grade of phosphorus impurity reached 0.04 mass% from 0.09 mass% (initial grade). Simultaneously, the iron grade and level of SiO2+Al2O3 impurity in the iron ore product from reverse flotation of the low-grade iron ore with DTAB collector reached 60.0 mass% and 4.4 mass%, which are acceptable levels for ironmaking.

As an ultra-fine crushing equipment, High-pressure Grinding Roller (HPGR) has unique advantages in crushing refractory ores, owing to its high efficiency and low energy consumption. Low-grade hematite ores from Anshan were crushed by a laboratory CLF-25-10 HPGR with different applied load, roll speed and feed moisture. The different operating factors on the fine crushed products characteristics were investigated and the suitable operating parameters were obtained. The results showed that the product became finer and specific grinding energy increased with applied load increasing, while the capacity did not vary obviously. The capacity was proportional to the roll speed, while product finess and specific grinding energy didn’t change significantly. The moisture of feed was beneficial to coarse particles crushing and went against fine particles crushing. Specific grinding energy increased and capacity increased and then decreased with the increase of feed moisture. It was obtained that applied load of 5.2N/mm2, roll speed of 0.18m/s and feed moisture of 5% were suitable to crushing effect. At these conditions, the percent of -0.074mm production was 21.84%, P80 of product was 2.55mm, specific grinding energy was 1.081Kwh/t and capacity was 1.521t/h.

This work aimed to upgrade a low-grade sedimentary phosphate ore through attrition scrubbing/desliming and an anionic/cationic reverse flotation technique. The mineralogical and chemical examination showed that the sample contained low-grade apatite minerals (P2O5 ~ 22.5%), and the main associated gangue minerals were gypsum and quartz. The effects of both collector and depressant dosage were investigated and optimized in each individual flotation process. The results of attrition scrubbing accompanied by desliming showed that a high content of P2O5 (27.97%) with a recovery of 72.1% was obtained in the coarse size fraction (+53 µm), and the majority of quartz and gypsum separated in the fine size fraction (−53 µm). The effect of using a new tall oil collector mixture was investigated during the anionic reverse flotation. Sodium tripolyphosphate (STPP) was used as a phosphate depressant during anionic and cationic reverse flotation. The flotation results of the deslimed sample demonstrated that cationic reverse flotation was much more desirable in terms of achieving a high grade and recovery of P2O5 compared to anionic reverse flotation. Considering the statistical design, a maximum grade of 31.23% P2O5 with a recovery of 95.22% was obtained in the non-floated fraction using 950.88 g/t of the collector (amine) and 500 g/t of the STPP.

Surplus coke oven gases (COGs) and low grade hematite ores are abundant in Shanxi, China. Our group proposes a new process that could simultaneously enrich CH4from COG and produce separated magnetite from low grade hematite. In this work, low-temperature hydrogen reduction of hematite ore fines was performed in a fixed-bed reactor with a stirring apparatus, and a laboratory Davis magnetic tube was used for the magnetic separation of the resulting magnetite ore fines. The properties of the raw hematite ore, reduced products, and magnetic concentrate were analyzed and characterized by a chemical analysis method, X-ray diffraction, optical microscopy, and scanning electron microscopy. The experimental results indicated that, at temperatures lower than 400°C, the rate of reduction of the hematite ore fines was controlled by the interfacial reaction on the core surface. However, at temperatures higher than 450°C, the reaction was controlled by product layer diffusion. With increasing reduction temperature, the average utilization of hydrogen initially increased and tended to a constant value thereafter. The conversion of Fe2O3in the hematite ore played an important role in the total iron recovery and grade of the concentrate. The grade of the concentrate decreased, whereas the total iron recovery increased with the increasing Fe2O3conversion.

Disclosure: D.A. Trukhina: Grant Recipient; Self; Russian Science Foundation (project N 19-15-00398-П). E.O. Mamedova: Grant Recipient; Self; Russian Science Foundation (project N 19-15-00398-П). P.A. Koshkin: Grant Recipient; Self; Russian Science Foundation (project N 19-15-00398-П). A.G. Nikitin: Grant Recipient; Self; Russian Science Foundation (project N 19-15-00398-П). G.A. Melnichenko: Grant Recipient; Self; Russian Science Foundation (project N 19-15-00398-П). Z.E. Belaya: Grant Recipient; Self; Russian Science Foundation (project N 19-15-00398-П). Multiple endocrine neoplasia type 1 (MEN1) is a rare disease caused by mutations in the MEN1 gene encoding the menin protein (gMEN1). This syndrome is characterized by the occurrence of parathyroid tumors, gastroenteropancreatic neuroendocrine tumors (GEP-NETs), pituitary adenomas, as well as other endocrine and non-endocrine tumors. Patients with MEN1 phenotype without MEN1 mutations are considered MEN1 phenocopies (phMEN1). It has not been studied whether the development of MEN1 phenocopies is determined by epigenetic changes, particularly by altered microRNA expression, which can affect menin. Materials & methods Single-center, case-control study: assessment of plasma microRNA expression in patients with gMEN1, phMEN1 and healthy controls. Morning plasma samples were collected from fasting patients and gender-matched controls and stored at –80C. Total RNA isolation was performed using miRNeasy Mini Kit with QIAcube. The libraries were prepared by the QIAseq miRNA Library Kit. Circulating miRNA sequencing was performed on Illumina NextSeq 500. Subsequent data processing was performed using DESeq2 bioinformatics algorithm. Results We enrolled 24 patients with gMEN1 and 12 patients with phMEN1, along with 12 gender-matched controls. The median age of gMEN1 patients was 39 [35; 46]; in phMEN1 — 59 [51;60]; control — 59 [51.5; 62.5]. The gMEN1 group differed in age (p<0,01) compared to phMEN1 and control groups. We divided all assessed microRNAs into 3 groups based on the significance of the results: the first group consisted of samples with the highest level of detected microRNAs (>50 counts), the second group — moderate (10–50), the third group — the lowest (<10).98 microRNAs were differently expressed in groups gMEN1 and phMEN1 (84 upregulated microRNAs, 14 — downregulated). We found increased expression of microRNAs in gMEN1 which interact with menin: hsa-miR-421 (p adj = 0.0004362), hsa-miR-664a-5p (p adj = 0.0037814). We found several microRNAs associated with intestinal and pituitary tumors in gMEN1 and phMEN1 groups: up-regulated hsa-miR-7-5p (p adj = 0.0000084); downregulated hsa-miR-423-5p (p adj < 0.000001) and hsa-miR-432-5p (p adj = 0.0087227). 84 microRNA were differently expressed in groups gMEN1 and control (67 up-regulated microRNAs, 17 — downregulated). When comparing gMEN1 with phMEN1 and control a decrease in hsa-let-7a-5p miRNA was found, which, according to the literature, is downregulated in Men1 gene knockout cell lines. The phMEN1 vs control group showed downregulation of hsa-miR-122-5p (p adj = 0.0080138) and upregulation of hsa-miR-191-5p (p adj = 0.0002144), hsa-miR-486-5p (p adj = 0.0491822) that has been detected in GEP-NETs. Conclusion We found microRNAs which could potentially become biomarkers in the differential diagnosis of gMEN1 and phMEN1. The results need to be validated using a different measurement method with a larger sample size. Presentation: Thursday, June 15, 2023

A hematite has low grade, fine disseminated size andcomplex disseminated relations, which are refractory iron ore. Using SLon pulsating high gradient magnetic separator, induction intensity 8500Oe, pulsating 20mm stroke, stroke of 120 beats / min), a crude iron ore concentrates a grade of 35.93.%, the recovery rate of 82.39% is obtained through high intensity magnetic separation.( The final iron concentrate with TFe grade of 64.83%,yield of 14.55% and iron recovery of 35.74% from the raw ores with TFe grade of 26.29％ was obtained, with the first stage grinding size being 50% -0.074mm and the second stage,95% -0.074mm.

Previous articleNext article FreeSummaries of Pre-Cambrian Literature of North America for 1909, 1910, 1911, and Part of 1912Edward SteidtmannEdward Steidtmann Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Journal of Geology Volume 23, Number 1Jan. - Feb., 1915 Article DOIhttps://doi.org/10.1086/622209 Views: 19Total views on this site Citations: 1Citations are reported from Crossref PDF download Crossref reports the following articles citing this article:Hans Becker Die präkambrische Geschichte des Lake Superior-Gebietes, Nordamerika, Geologische Rundschau 22, no.66 (Dec 1931): 385–411.https://doi.org/10.1007/BF01810145