Iron Ore Research Articles

A Comparison Between the Reduction Behavior of DRI and BF Pellets in H2 and CO Atmospheres

AbstractThe reduction behavior of two different iron ore pellets that are used in blast furnace (BF) and direct reduction (DRI) was investigated in this research. Single pellets reduction experiments were conducted isothermally using pure CO and H2 as reducing agent in the temperature range 700 °C to 1100 °C. Reduction by H2 was significantly faster than reduction by CO for both pellets and reduction rate increased with increasing the temperature. When CO was used as the reducing agent, the BF pellet achieved a reduction degree of 32% at 700 °C and 67% at 800 °C, while the DRI pellet reached 28% and 59% at the same temperatures. This difference is due to the lower magnetite content in BF pellets (1.93%) compared to DRI pellets (9.11%). However, at 1000 °C and 1100 °C, the DRI pellet achieved 93% and 100% reduction, and the BF pellet 88% and 94%, respectively, due to the higher porosity in the DRI pellet (38%) compared to BF (32%). Kinetics controlling model for hydrogen reduction of both pellets suggested as D2 (2D Diffusion through the solid ash), however, A1 (1D Nucleation and growth) and R3 (3D Chemical reaction) were found as the most compatible models for CO reduction of DRI and BF pellets, respectively. Graphical Abstract

Addressing Uncertainty in Renewable Energy Integration for Western Australia’s Mining Sector: A Robust Optimization Approach

The mining industry is a key contributor to Western Australia’s economy, with over 130 mining operations that produce critical minerals such as iron ore, gold, and lithium. Ensuring a reliable and continuous energy supply is vital for these operations. This paper addresses the challenges and opportunities of integrating renewable energy sources into isolated power systems, particularly under uncertainties associated with renewable energy generation and demand. A robust optimization approach is developed to model a multi-source hybrid energy system that considers risk-averse, risk-neutral, and risk-seeking strategies. These strategies address power demand and renewable energy supply uncertainties, ensuring system reliability under various risk scenarios. The optimization framework, formulated as a mixed integer linear programming problem and implemented in Python using the Gurobi Optimizer, integrates renewable energy sources such as wind turbines, photovoltaic arrays, and demand response programs alongside traditional diesel generators, boilers, combined heat and power units, and water desalination. The model ensures reliable access to electricity, heat, and water while minimizing operational costs and reducing reliance on fossil fuels. A comprehensive sensitivity analysis further examines the impact of uncertainty margins and the value of a lost load on the total system cost, providing insights into how different risk strategies affect system performance and cost-efficiency. The results are validated through three case studies demonstrating the effectiveness of the proposed approach in enhancing the resilience and sustainability of isolated power systems in the mining sector. Significant improvements in reliability, scalability, and economic performance are observed, with the sensitivity analysis highlighting the critical trade-offs between cost and reliability under varying uncertainty conditions.

Research on Deoxygenation Pyrolysis of Larch Based on Microwave Heating

Aiming at problems such as low energy utilization efficiency and the high oxygen content of liquid products in the process of conventional biomass conversion to prepare liquid fuels, the deoxygenation pyrolysis technology route of larch based on microwave heating was proposed in this paper. Two kinds of calcium–iron composite oxygen carriers, including Ca2Fe2O5 with iron ore structure and CaFe2O4 with spinel structure, were successfully synthesized. The results showed that the selectivity of ideal products was improved under the action of single iron-based oxygen carriers; however, the deoxygenation effect was undesirable. Under the action of CaFe2O4, the selectivity of aromatics was increased to 27.17% and the selectivity of phenols was decreased to 36.46%, which mainly existed in the form of O1P with low oxygen content. The oxygen content of bio-oil was reduced to 27.70% and the calorific value was increased to 29.05 MJ/kg, thus leading to a great improvement in the quality of liquid products. After the pyrolysis reaction, the Fe2P3/2 XPS peak of CaFe2O4 shifted to a higher binding energy and was characterized as higher valence of iron oxide, which proved its “oxygen grabbing” capacity in microwave pyrolysis. The deoxygenation conversion of larch without an external hydrogen supply was achieved.

Characterisation of Varying Iron Ores and Their Thermal Decomposition Kinetics Under HIsarna Ironmaking Conditions

In the pre-reduction cyclone of the HIsarna process, both thermal decomposition and gas reduction of the injected iron ores occur simultaneously at gas temperatures of 1723–1773 K. In this study, the kinetics of the thermal decomposition of three iron ores (namely OreA, OreB and OreC) for HIsarna ironmaking were analysed as an isolated process with a symmetrical thermogravimetric analyser (TGA) under an inert atmosphere. Using various methods, the chemical and mineralogical composition, particle size distribution, morphology and phase distribution of the ores were analysed. The ores differ in their mineralogy and morphology, where OreA only contains hematite as iron-bearing phase and OreB and OreC include goethite and hematite. To obtain the kinetic parameters in non-isothermal conditions, the Coats–Redfern Integral Method was applied for heating rates of 1, 2 and 5 K/min and a maximum temperature of 1773 K. The TGA results indicate that goethite and hematite decomposition occur as a two-stage process in an inert atmosphere of Ar. The proposed reaction mechanism for the first stage of goethite decomposition is chemical reaction with an activation energy ranging from 46.55 to 60.38 kJ/mol for OreB and from 69.90 to 134.47 kJ/mol for OreC. The proposed reaction mechanism for the second stage of goethite decomposition is diffusion, showing an activation energy ranging between 24.43 and 44.76 kJ/mol for OreB and between 3.32 and 23.29 kJ/mol for OreC. In terms of hematite decomposition, only the first stage was analysed. The proposed reaction mechanism is chemical reaction control. OreA shows an activation energy of 545.47 to 670.50 kJ/mol, OreB one of 587.68 to 831.54 kJ/mol and OreC one of 424.31 to 592.32 kJ/mol.

Effect of Bacillus licheniformis on Growth, Bone Mineralization, and Intestinal Microbiota in Broilers Fed Cowpea Diets

This study investigates the effects of the Bacillus licheniformis (BL) ATCC 21424 strain, as a potential bacterial probiotic in broiler diets based on soybean meal (SBM) or cowpea seeds (CWP), on growth performance (GP), bone mineralization, and intestinal/fecal microbiota status (0 to 42 d age). A 2 × 2 factorial arrangement was employed in a completely randomized design, with four dietary treatments: SBM and CWP diets with or without BL supplementation (1.0 × 1011 CFU spores g−1 feed). A total of 480 one-day-old mixed-sex Ross 308 broiler chickens were randomly assigned to the treatments, with 6 pens of 20 chicks each. The results showed that broilers fed with CWP diets showed comparable body weight gain (BWG), feed intake (FI), and feed conversion rate to those fed the SBM diet (p > 0.05). The inclusion of BL improved BWG during the grower and finisher periods (p = 0.01) and overall study (p < 0.001), resulting in a numerical increase in FI (p = 0.054). In addition, BL in birds’ diets reduced abdominal fat (p = 0.032) and influenced cecum weight (p = 0.040). Additionally, BL improved tibia iron (Fe) and phosphorus (P) bone mineralization and reduced the calcium–phosphorus (Ca:P) ratio (p = 0.0001). Microbial analysis revealed that BL inclusion decreased Coliforms counts in the CWP diet (p = 0.073), reduced E. coli in the ileum (p ≤ 0.05), and lowered Clostridium spp. and Enterococcus spp. in the cecum broilers on SBM diets (p ≤ 0.05). The presence of Staphylococcus spp. in broiler feces was also reduced in both SBM and CWP groups (p < 0.05). In conclusion, the addition of BL to broiler diets enhanced growth performance and bone mineralization and positively influenced gut and excreta bacterial populations in both SBM and CWP diets.

Development and assessment of a biomass-based energy system for green steel production: A thermodynamic study

ABSTRACT Steel is the fundamental pillar of contemporary society, given its significant greenhouse gas emissions, rapid transformation is required for deep decarbonization of the iron and steel industry. This paper proposes a strategy to generate green steel through the H2-DRI-EAF (Hydrogen direct reduced iron processed in an electric arc furnace) process, leveraging biomass as the primary feedstock. The proposed configuration contains a biomass gasifier to generate hydrogen, which is further used in a shaft furnace to reduce iron ore and is fed to an electric arc furnace to produce Green Steel. India serves as the focal point for this study, with agricultural residue from the four most abundant crops selected as the primary feedstock. With these chosen feedstocks, the system demonstrates the capacity to produce approximately 0.1 kg of hydrogen per kg of biomass. Operating with an overall energy efficiency of 29.2% and exergy efficiency of 41.4%, the plant exhibits a crucial characteristic: the ability to seamlessly integrate different feedstocks without significantly affecting its overall performance. The aim of the current study is to promote bioenergy as a viable pathway for the decarbonization of steelmaking processes.

Impact of low-grade iron ore on sintering reactions: Rapid heating experiments and thermodynamic modeling

BackgroundSinter is a primary feedstock for blast furnace-based ironmaking. Recently, the proportion of low-grade iron ore, which contains a high amount of gangue (mainly SiO2), has been increasing in the sintering process. Therefore, the impact of increased SiO2 content on the quality of sinter needs to be clarified. MethodsIn this study, we designed a rapid-heating furnace to simulate the actual thermal profile of the sintering process. The effects of basicity values, sintering temperature, and atmosphere, on the microstructure and phase formation of the Fe2O3-CaO-SiO2 ternary mixtures during sintering reactions, are investigated using X-ray diffractometry and scanning electron microscopy. The experimental results are analyzed using CALPHAD-type computational thermodynamics. Significant findingsWe found that solid-state reactions dominate at the lower temperature of 1250 °C, while liquid-assisted sintering occurs at the higher temperature (1300 °C). As the SiO2 content in the sinter increases, the content of the calcium-ferrite bonding phase decreases, while the content of Ca2SiO4 and Fe2O3 increases. Regarding the role of the atmosphere, more calcium ferrite bonding phases form under a lower oxygen partial pressure compared to an ambient atmosphere, which facilitates the densification of the Fe2O3-CaO-SiO2 sinter. In addition, a guideline for sintering operation with low-grade iron ore is proposed.

Production process of 800 t/d sintered lime rotary kiln

This paper presents a detailed analysis of the production process and technical characteristics of the 800t/d sintered lime rotary kiln in Beitai Iron Mine of Bensteel Group Corporation Limited. The production process encompasses a number of key stages, including the charging of raw materials, firing, the crushing and screening of finished products, storage and transportation, exhaust gas treatment, and pulverized coal preparation. The study will prove a valuable point of reference for the enhancement of the overall performance of the domestic sintered lime industry.

Mineral composition of xenoliths of transformed tholeiitic basalts in ore-hosting rocks of the Rudnogorskoe iron ore deposit, Eastern Siberia

Research subject. Variously-altered tholeiitic basalt xenoliths in ore-hosting rocks from the Rudnogorskoe iron ore deposit, the Angaro-Ilim region of Eastern Siberia. Aim. To identify the sequence of mineral transformations during the formation of magnetite ores. Materials and methods. The mineral composition of weakly-altered and hematitized xenoliths of tholeiitic basalts in skarned rocks and relics of basaltic hyaloand lithoclasts in varying degrees magnetitized volcaniclastites were studied. Minerals were identified using a powder X-ray diffractometer with the determination of the quantitative ratios of mineral phases by SHIMADZU XRD-6000 and DRON-2.0 diffractometers and using the microscopic (Olympus BX51) and electron microscopic (Tescan Vega 3 sbu with an Oxford Instruments Xact energy-dispersive analyzer) and IR spectroscopic (Spectrum One IR Fourier-spectrometer and a Multiscope microscope, PerkinElmer) research methods. Results. In xenoliths of weakly-altered tholeiitic basalts, volcanic glass is smectitized and partially replaced by secondary aggregates of chlorite and carbonate. In hematitized xenoliths, the smectite-hematite mineral association contains skarn epidote and garnet. Smectite aggregates, partially transformed into magnetite mass, are present in the magnetitized volcaniclastites. The studied smectites are classified as saponite according to the obtained values of basal reflections d001 in the range of 14.76–15.23 Å and calculated crystal chemical formulas. The differences in the morphology, chemical composition, and IR spectrometric characteristics of smectites reflect the varying degrees of transformation of the tholeiitic basalts in multi-stage ore-forming processes.

Geological Features and Ore Formation Pattern of Jinzhong Bauxite Mine, Shanxi Province, China

Bauxite is located in the lower part of the Benxi Formation, and the prospecting project shows that the distribution of bauxite ore bodies in the area is discontinuous, and there are differences in the thickness of the ore bodies. To have a clearer understanding of the bauxite ore bodies and metallogenic pattern in the census area, this study has made use of the prospecting project data, sample analysis results, etc., and combined with the geological and tectonic background of the area, the stratigraphic spreading characteristics of the bauxite ore body spatial spreading, ore characteristics and ore controlling factors in the area have been explored and researched. The bauxite ore bodies in the study area are stratified but the ore-bearing rock system is influenced by the Ordovician paleokarst geomorphology and intermittently distributed horizontally, which can be distinguished into three different ore bodies. The bauxite ore body and Shanxi-style iron ore are associated with hard clay ore, in which the ore minerals are mainly monohydrate duralumin. The natural ore type can be divided into dense bauxite and oolitic bauxite. Bauxite in this area mainly originated from the basal Ordovician carbonate rocks, with a combination of iron-rich and aluminum-rich layers, and is a typical carbonate rock sedimentary deposit of ancient weathering crust.

A key feedback loop: building electricity infrastructure and electrifying metals production.

Energy infrastructure requires metals, and metals production requires energy. A transparent, physical model of the metals-energy system is presented to explore under what conditions this dependence constrains or accelerates the transition to a net-zero economy. While the mineral (as high as 340 Mt yr-1 iron ore, 210 Mt yr-1 limestone, 250 Mt yr-1 bauxite and 5.5 Gt yr-1 copper ore in the 2040-2050 decade, assuming no improvements) and total energy (up to 22 EJ yr-1) requirements for building low-carbon energy infrastructure are significant, it compares favourably with the current extraction and energy use supporting the fossil fuel system (15 Gt yr-1 fossil minerals and ~38 EJ yr-1). There are levers to significantly reduce material use and associated impacts over time. The metals industry can play a key reinforcing role in the transition by adapting to the increasing supply of renewable electricity. Specifically, direct electrolysis can extract metal from ore close to the thermodynamic limit, to make efficient use of low-C electricity. The unique features of emerging technologies for iron extraction, molten oxide electrolysis and molten sulphide electrolysis are considered in this evolving system. Electrification enables elegant separations and provides a pathway to build out infrastructure while reducing environmental impacts, though material efficiency measures will still be crucial to meet 2050 carbon budgets.This article is part of the discussion meeting issue 'Sustainable metals: science and systems'.

Effects of nanoplastics on the growth, transcription, and metabolism of rice (Oryza sativa L.) and synergistic effects in the presence of iron plaque and humic acid

Nanoplastics (NPs) can adversely affect living organisms. However, the uptake of NPs by plants and the physiological and molecular mechanisms underlying NP-mediated plant growth remain unclear, particularly in the presence of iron minerals and humic acid (HA). In this study, we investigated NP accumulation in rice (Oryza sativa L.) and the physiological effects of exposure to polystyrene NPs (0, 20, and 100 mg L−1) in the presence of iron plaque (IP) and HA. NPs were absorbed on the root surface and entered cells, and confocal laser scanning microscopy confirmed NP uptake by the roots. NP treatments decreased root superoxide dismutase (SOD) activity (28.9–44.0%) and protein contents (31.2–38.6%). IP and HA (5 and 20 mg L−1) decreased the root protein content (20.44–58.3% and 44.2–45.2%, respectively) and increased the root lignin content (22.3–27.5% and 19.2–29.6%, respectively) under NP stress. IP inhibited the NP-induced decreasing trend of SOD activity (19.2–29.5%), while HA promoted this trend (48.7–50.3%). Transcriptomic and metabolomic analysis (Control, 100NPs, and IP-100NPs-20HA) showed that NPs inhibited arginine biosynthesis, and alanine, aspartate, and glutamate metabolism and activated phenylpropanoid biosynthesis related to lignin. The coexistence of IP and HA had positive effects on the amino acid metabolism and phenylpropanoid biosynthesis induced by NPs. Regulation of genes and metabolites involved in nitrogen metabolism and secondary metabolism significantly altered the levels of protein and lignin in rice roots. These findings provide a scientific basis for understanding the environmental risk of NPs under real environmental conditions.

MAKING QUALITY AGGLOMERATES USING LEAN IRON ORES FOR SUSTAINABLE IRON-MAKING

For sustainable iron making and hassle-free operation of large blast furnaces (BF) and direct reduced iron (DRI) units, a more prepared burden in the form of good quality agglomerates is required. However, the situation is becoming more and more challenging owing to the faster depletion of high-grade iron ore, increased fines generation due to mechanized mining, wide variations in chemistry & mineral characteristics, high content of gangue minerals, and poor liberation characteristics. The growing demand for steel vis-à-vis iron ores has necessitated the utilizationof low-grade iron ores for steel production. The challenges lie in the economic extraction of lean ores and their conversion into quality agglomerates for use in iron making. The utilization of low-grade iron ores has assumed greater significance for the optimal utilization of natural resources and the sustainability of the steel industry. Thebeneficiated concentrate of BHQ iron ore from the Sandur Schist belt is used for the pellets. Green green pellets with 1.21 kg/pellet GCS and drop strength of 12 drop number were producedat an optimum binder of 1.2% and moisture of 9.5%. Induration of green pellets at a firing temperature of 1300 °C has resulted in adequate pellet properties of 237 kg/pellet of CCS, 91.87% TI, 7.41% RDI, and 22.56% porosity. An attempt is made to produce pellets suitable for iron making by optimizing various raw materials and operating parameters.This will reduce dependency on high-grade ores and effectively utilize low-grade iron ore to produce good-qualityiron-making pellets.

Study on the effect and mechanism of coarse magnetite on the flotation of fine-grained hematite

Lean hematite ore is one of the refractory iron ores in China due to its fine crystal size, deep oxidation degree and complex mineral composition. With the deep mining of mine ore, the disseminated particle size of iron minerals is finer, and the ore properties are more complex and difficult to be separated. Therefore, the research on high-efficiency beneficiation technology of fine-grained lean hematite ore is the requirement and important direction of the development of refractory iron ore beneficiation. In this paper, the carrier flotation method is used to comprehensively recover hematite, and the addition of coarse-grained magnetite can effectively improve the recovery rate of fine-grained hematite. The flotation results show that when the ratio of magnetite to hematite is 1: 1, the recovery rate of iron ore can reach more than 96.34%, and the efficient recovery is realized. Based on the results of pure mineral test, the carrier flotation test of Anshan lean hematite ore was carried out. The results show that the reverse flotation concentrate product with TFe grade of 67.88% and total iron recovery of 84.81% can be obtained, and the TFe grade of the reverse flotation tailings is 24.20%. It can be seen that compared with the traditional process, the grade of carrier flotation tailings is 2.37 percentage points lower than that of the original reverse flotation tailings; the carrier reverse flotation process can effectively improve the recovery rate of iron concentrate. In addition, the theoretical analysis of carrier flotation was carried out by contact angle, zeta potential, mineral phase microscope, SEM and XPS. It was found that the collision probability between fine mineral particles and bubbles was low, which limited the recovery of fine mineral particles in the flotation process. Fine-grained hematite can be non-selectively attached to the carrier particles, thereby affecting the adsorption of starch on it, thereby improving the recovery rate of fine particles; The carrier reverse flotation can further improve the flotation efficiency by gravity and shear force. Carrier reverse flotation provides a new idea for effective recovery of iron ore.

Degradation study of δ-hexachlorocyclohexane by iron sulfide nanoparticles: elucidation of reaction pathway using compound specific isotope analysis and pH variation

pH influences the reactivity of iron (II) minerals towards halogenated pollutants like hexachlorocyclohexanes (HCHs). To explore these incompletely understood interactions, we investigated the carbon isotope fractionation of the δ-HCH isomer during dehalogenation by iron sulfide at pHs spanning a pH range across slightly acidic to alkaline domains (5.8 to 9.6). The δ-1,3,4,5,6-pentachlorocyclohex-1-ene (δ-PCCH) was the intermediate degradation product, while benzene, monochlorobenzene (MCB), but especially 1,2-dichlorobenzene (1,2-DCB), and 1,2,4-trichlorobenzene (1,2,4-TCB), were the main degradation products of δ-HCH. These degradation products suggested dehydrochlorination as the main degradation pathway of δ-HCH by iron sulfide. Different kinetic experiments indicate that the rate constants (ka) during dechlorination of δ-HCH by iron sulfide rose with pH: 0.003 d-1 (pH 5.8) < 0.034 d-1 (pH 8) < 0.085 (pH 9.3) < 0.286 d-1 (pH 9.6). Upon Rayleigh model calculations, an enrichment factor (εC) of -7.8 ± 1.0 ‰ was calculated for δ-HCH dehalogenation by FeS at pH 8.0. This suggests an apparent kinetic isotope effect (AKIEC) value of 1.049 ± 0.006 for dehydrohalogenation. The magnitude of the isotope effect from this paper furthermore supports dehydrohalogenation and opens the possibility to study the degradation of HCHs by iron (II) minerals containing FeS as mackinawite in oxygen-deprived environments.

High-temperature thermochemical conversion of iron ore tailings into diopside and akermanite-based composite materials

Iron ore tailings (IOTs), the residue materials generated during iron ore processing, pose environmental challenges due to their massive volume and potential impact on ecosystems. This study proposes a sustainable approach to manage and utilize this solid waste by converting it into value-added composite materials through high-temperature thermochemical reactions. Experiments are conducted in a tubular reactor at various reaction temperatures and times, and the resulting product samples are comprehensively characterized to elucidate their chemical compositional, physical, microstructural, thermal, and electrical properties. The results reveal that at optimal reaction temperatures (1230–1260 °C) and reaction times (20–120 min), the synthesized product is predominantly composed of diopside (CaMgSi2O6) and akermanite (Ca2MgSi2O7). Additionally, we demonstrate that the product can be diopside-rich or akermanite-rich when blending silica and MgO powders into the IOTs to control the starting material composition, opening a promising avenue for large-scale sustainable utilization of industrial solid waste.

Unlocking new export opportunities: An open-source framework for assessing green iron and steel supply chains

Globally traded commodities such as iron and steel are coming under international scrutiny owing to their significant embedded greenhouse emissions. Commodity export-oriented nations must explore opportunities for decarbonising these supply chains or risk losing market share as customers seek cleaner alternatives and as initiatives such as carbon border adjustment mechanisms (CBAM) come into effect. Here we present an open-source model developed to assist industry and other stakeholders in assessing the costs of potential CO2 abatement pathways in supplying green iron ore, green iron, or green steel to key global markets. Using a case study, we assess the development of a green steel supply chain from major iron ore producers of Australia, Brazil, and Sweden, to key markets in Europe, China, and India. Projected costs of renewable energy and other key technologies are used to estimate possible future costs of different decarbonisation pathways. Our modelling suggests that by 2050, export costs of green iron ore, iron and steel could range from 48 to 150, 370–600 and 540–810 USD/tonne respectively. Access to low-cost renewable energy is the key driver of cost reductions for value added products such as iron and steel, and given their substantial renewable energy potential, in 2050 Australia and Brazil could outcompete Sweden in providing these products, with both even outcompeting Sweden in exporting to the European market. The release of our model as open source allows any and all stakeholders to explore the implications of key technology and market uncertainties over least cost green iron and steel supply chains.

Simultaneous removal of vanadium and nitrogen in two-stage vertical flow constructed wetlands: Performance and mechanisms

Vanadium (V(V)) and nitrate, as co-concomitant pollutants in water bodies, pose potential threats to the eco-environment and human health. This study was to reveal the feasibility of simultaneous removal of V(V) and nitrate in the series-wound vertical flow constructed wetlands (CWs) with iron ore (B-CWs)/manganese ore (C-CWs)-wood substrates. The results showed that B-CWs could achieve efficient V(V) and NO3−-N removal with the influent of 2 and 10 mg/L (V(V)/NO3−-N = 1:5), respectively. With the increase of V(V)/NO3−-N ratio (V(V)/NO3−-N = 1:1), B/C-CWs exhibited better combined pollution removal. Even when nitrate was removed (V(V)/NO3−-N = 1:0), the systems could maintain a good capacity for V(V) removal. High V(V) (20 mg/L) significantly inhibited V(V) removal, with a slight recovery of the performance as the decrease of V(V) influent. High NO3−-N concentration (10 mg/L) effectively enhanced V(V) removal and restored C-CWs to the better level. V(IV) precipitates/oxides were the main reducing end-products. High abundance of V(V)-reducing bacteria and iron/manganese cycling pumps ensured efficient V(V) removal.

Separation of iron and copper in skarn deposits from the Yueshan ore field, eastern China: The control of magma physicochemical conditions

Iron and copper mineralization in the Yueshan ore field is intricately linked to the Cretaceous Yueshan diorite intrusions, yet they frequently materialize as distinct deposits. Despite this, the key factors dictating the segregation of these metals remain poorly understood. To gain insights into the role of magma physicochemical conditions in this segregation, we conduct a comparative analysis of the U-Pb dating, whole-rock geochemistry, and mineral chemistry of the newly uncovered Zhuchong skarn iron deposit (Fe:Cu ratio = 197) and the Anqing skarn copper deposit (Fe:Cu ratio = 35), both situated within the Yueshan ore field of the Middle Lower Yangtze River Valley Metallogenic Belt (MLYB) in eastern China. The garnet U-Pb dating of the Zhuchong and Anqing deposits are 138.3 Ma and 137.2 Ma, respectively, which are consistent with the zircon U-Pb dating (138.3 Ma) of diorites from the Zhuchong and Anqing deposit. The emplacement of diorite intrusions and Fe-Cu mineralization occurred at 137 – 139 Ma, consistent with the Cu-polymetallic mineralization epoch (145 – 137 Ma) in the MLYB. The diorite samples from the Yueshan intrusion and the Zhuchong and the Anqing deposits exhibit typical characteristics of adakites, such as high Sr/Y (28 – 174) and (La/Yb)N (26 – 40), along with similar and enriched Sr-Nd (εNd(t) = − 7.95 ∼ − 7.33) and zircon Hf isotope (−14.9 ∼ − 6.4) compositions. This suggests that the magma source regions for the diorites from the three locations were all likely derived from the melting of sediment-rich subducted oceanic crust with the potential of copper mineralization. However, chemical compositions of zircon, apatite, and amphibole from diorites reveal that diorites in the Zhuchong and Anqing deposits were emplaced at different depth levels and physicochemical conditions. Specially, the diorite in the Zhuchong Fe deposit was emplaced at shallower levels (1.9 km), with higher oxygen fugacity (mean = ΔNNO + 1.9) and fluorine concentration (2096 ppm), water deficiency (3.3 ± 0.4 wt%), sulfur-poor conditions (avg = 494 ppm), lower pressure (49.2 MPa), temperature (746 ℃), and chlorine (945 ppm) concentration relative to the Anqing Cu deposit (Emplacement depth: 2.53 km; oxygen fugacity: ΔNNO + 1.5; F: 1720 ppm; H2Omelt: 3.9 ± 0.4 wt%; S: 816 ppm; P: 66.9 MPa; T: 778 ℃; Cl: 945 ppm).It is proposed that a shallower emplacement depth may have promoted extensive exsolution of magmatic fluids, leading to the outward migration of water, S, Cl, and Cu elements, which resulted in the high iron-copper ratio observed at the Zhuchong Fe deposit. This process could have led to the relative Cl-poor nature and smaller Cu size at the Zhuchong Fe deposit, as well as the widespread development of vein-type copper ore bodies in the region.

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.