High-grade Ore Research Articles

Enzymatic bio-oxidation technology as novel approach for pretreatment of refractory sulfide ores.

Surging global demand for titanium, driven by its essential role in aerospace, transportation, chemical industries, and as a white pigment, is intensifying pressure on scarce high-grade ores, like rutile, leading to their rapid depletion. As a result, ilmenite (FeTiO3) mineral sands are emerging as the cornerstone of future titanium supply. However, conventional ilmenite processing routes are energy-intensive, carbon-emissive, and require multiple reduction and refining stages. Here, a single-step hydrogen plasma reduction process is introduced that simultaneously produces two critical materials for a sustainable economy, high-purity iron and a Titania-rich compound, directly from low-grade ilmenite concentrates, without fossil fuels and direct CO2 emissions. This process unifies smelting, reduction, and refining (of both iron and Titania oxide mixture) in one operation, at rapid kinetics and selective impurity removal. Silica, an impurity usually removed in a separate chemical step, is reduced by ≈75% within the proposed plasma-based operation, enabling direct downstream use of the Titania-rich compound. The resulting iron achieves purity high enough for direct use in steel production, while the Titania-rich compound serves as an upgraded CO2-free precursor for titanium metal or pigment production. This work introduces a zero-carbon metallurgical route for maximizing value from low-grade ilmenite while advancing decarbonized industrial metals processing.

IntroductionThe Yangtze River Metallogenic Belt (YMB) hosts extensive Mesozoic iron oxide-apatite (IOA) and skarn iron-copper deposits, with significant high-grade iron ore potential. However, the lack of systematic understanding of mineralization types, distribution controls, and metallogenic mechanisms limits exploration efficiency, particularly due to widespread alluvium cover.MethodsWe integrated aeromagnetic data with reduction-to-pole (RTP) transformation, upward continuation, and Curie point isothermal surface calculations. A novel robust principal component analysis (RPCA) based on the inexact augmented Lagrangian method (IALM) was applied to discriminate mineralization zones. Structural controls on deposits were analyzed using updated aeromagnetic and gravity datasets.ResultsProspective zones for iron oxide-apatite (IOA) and skarn mineralization were systematically delineated, demonstrating a robust spatial correlation between ore-bearing magmatic systems and iron deposit localization. The study further highlights the dominance of deep-seated structural frameworks and magmatic conduits in governing the distribution of mineralization, emphasizing their role as primary controls on ore formation.

Genesis of high-grade ore shoots in lode gold deposits: An example from the Sidaogou gold deposit, NE China

This study presents a comprehensive geochemical investigation of the undeveloped Pb-Zn mineral deposits in the My Duc area of Quang Binh Province, central Vietnam. The regional geology includes the upper Silurian to lower Devonian Dai Giang Formation (limestone, mudstone, sandstone, and schist), the upper Devonian Co Bai Formation, the lower Carboniferous La Khe Formation (limestone), and the upper Carboniferous to lower Permian Muong Long Formation (recrystallized limestone), with Cretaceous lamprophyre intrusions. The Pb-Zn ore bodies are primarily hosted in dolomitized and recrystallized limestone and are classified into primary and oxidized zones. The main ore minerals are sphalerite, galena, smithsonite, and associated sulfide and carbonate minerals. A total of 31 rock and ore samples were collected from ore bodies and surrounding rocks, followed by X-ray diffraction (XRD), electron probe micro analysis (EPMA), and chemical analyses. Sphalerite from Dong Tri Mountain shows high Zn contents (64.5-67.7 wt.%), low Fe, and moderate Cd concentrations, indicating high purity. The average Zn and Pb concentrations in ore bodies were 1,230 ppm and 27,700 ppm, respectively, with Zn reaching up to 16,000 ppm in high-grade ores. Geochemical anomalies of Cd, Sb, As, and Ag were also detected. Additionally, a regional geochemical survey was conducted over an area of 180 km<sup>2</sup>, using 90 stream sediment and 90 heavy mineral samples. Anomalous zones were identified near the Tau A and Len Dong Areas, where multielement enrichment indicates hydrothermal vein-type mineralization. These zones are considered promising targets for future exploration. The findings suggest that the My Duc Pb- Zn deposits exhibit strong geochemical signatures typical of epithermal processes, and further trenching, drilling, and geophysical surveys are recommended to define economically viable ore zones.

The efficient extraction of copper is becoming increasingly complex due to the declining availability of high-grade ore deposits and the implementation of more rigorous environmental standards. These constraints have heightened the demand for advanced technologies that optimize copper recovery through processes, such as flotation. Flotation, a widely employed physicochemical separation technique, is highly sensitive to operational parameters, making its optimization essential for maximizing metal recovery, reducing operational costs, and promoting environmentally responsible resource utilization and conservation. This study investigates applying Machine Learning (ML) techniques to improve flotation process performance. Specifically, this study assesses the predictive performance of four ML algorithms: random forest, support vector machine, K-means clustering, and Artificial Neural Networks (ANNs) for estimating copper recovery in flotation processes. The models were trained and validated using experimental data from a laboratory-scale flotation system. Among the evaluated algorithms, the ANN achieved the highest prediction accuracy of 98.69%, demonstrating a strong capacity to model complex nonlinear interactions among critical process variables. Complementary, disequilibrium, and entropic measures validate the results using the probability selection between three classes. These results highlight the potential of ML-based approaches to support process optimization, enhance recovery efficiency, and contribute to the sustainable development of copper extraction technologies.

Certain hydrometallurgy processes are used in the majority of the main metal manufacturing processes that yield a final metal product. Tin is an essential strategic metal that is widely used in novel energy components, aircraft, and other cutting-edge industries. Yet, with decreasing availability of high-grade tin ores, use of low-grade tin metals for metal tin processing is emerging as a significant development. However, there are intrinsic difficulties with low-grade tin ores that prevent them from being used directly in tin extraction. Although hydrometallurgy is still a useful technique for improving ore grade, problems such mineral complexity and fine particle dispersal still prevail. The three fundamental processing phases are recovery, concentration/purification, and extraction. In this study, hydrometallurgical processing will be explored in terms of hydrometallurgical essentials and their applications to tin treatment. The essential concepts and extraction techniques presented in this study can be applied to a wide range of metals. Given this, the current paper offers a thorough analysis of the properties of cassiterite resources, oxidative reagents, and pertinent case studies. Through an exploration of cassiterite's several dissolution techniques, the study emphasizes its leaching efficiency and distinctions between different oxidative reagents. In addition, it highlights substantial barriers to cassiterite dissolution and suggests determined, practical approaches to facilitate the effective use of tin resources, which will promote the long-term growth of the tin sector.

The increasing demand for lithium-ion batteries particularly for electric vehicles underscores the importance of improving the sustainability of lithium mining operations. The depletion of high-grade lithium ore deposits has necessitated the upgrading of medium to low-grade ores for lithium extraction. Spodumene is the most commercially exploited lithium-bearing mineral found in pegmatites due to its high lithium content. Ore sorting can be used for early rejection of up to 60% of gangue minerals prior to preconcentration. Dense media separation is a viable spodumene beneficiation method. However, as case studies have shown, flotation may still be required to process middlings and the undersized fraction, which falls outside the particle size range effective for dense media separation. Magnetic separation can be conducted during or after flotation to remove iron impurities in lithium concentrates. While fine particle flotation has historically achieved high recovery rates, their economic feasibility is increasingly questioned due to intensive comminution requirements. Coarse particle flotation in mechanical flotation cells for instance is inefficient due to turbulence-induced detachment of coarse particles. Coarse particle beneficiation using fluidized bed flotation cells can offer advantages such as reduced grind size and environmental footprint. Despite proven energy savings and recovery efficiencies in other mineral sectors, their application in lithium mining operations remains limited to pilot scale. Also, research in this area is underexplored. This review addresses this gap by evaluating the feasibility, potential benefits and challenges of integrating ore sorting, dense media separation, magnetic separation and fluidized bed flotation with the HydroFloat, NovaCell and Reflux cells into lithium ore beneficiation flowsheets. Key challenges identified include high water consumption and the inadvertent entrainment of fine particles requiring desliming steps. Furthermore, this review acknowledges the challenges in spodumene beneficiation due to the structural similarities among silicate minerals and highlights relevant pretreatment methods to improve selectivity, recovery and grade.

Texture and geochemistry of magnetite from the Jinshandian deposit, eastern China: Implications for the formation of high-grade Fe ore in skarn system

Abstract The high-grade stratabound copper ores of the Central European Kupferschiefer are one of the world’s most important sources of silver. Despite its economic significance, the mineralogical partitioning of silver within the Kupferschiefer ores is generally not well understood, other than the fact that silver minerals are not sufficiently abundant to account for the bulk of the silver content. This study provides the first fully quantitative silver deportment for Kupferschiefer-type ores, using the Spremberg-Graustein-Schleife project in Germany as a case study. Our comprehensive analytical approach integrates scanning electron microscope (SEM)-based automated mineralogy and electron probe micro-analysis (EPMA) on exploration drill-core samples collected from different host rocks and different metal tenor. The results were validated using bulk geochemical data, and uncertainties were assessed with Monte Carlo simulations. The results demonstrate that the majority of the silver within high-grade Cu-rich ores occurs as a trace constituent in the ore-forming Cu(-Fe) sulfides (chalcocite group minerals, covellite, bornite, and chalcopyrite). In samples containing little copper, however, Fe sulfides host the majority of the silver in the form of micro-inclusions within copper-enriched crystal growth zones and substitution within the crystal lattice. The close association of copper and silver has important implications for ore genesis and mineral processing. These implications may well transfer to other by-products and other examples of polymetallic sediment-hosted copper mineral systems.

The Qiubudong silver deposit on the western margin of the Fuping ore cluster in the central North China Craton is a representative breccia-type deposit characterized by relatively high-grade ores, thick mineralized zones, and extensive alteration, indicating considerable potential for economic resource development and further exploration. Previous studies on this deposit have not addressed its genetic mineralogical characteristics. This study focuses on pyrite and quartz to investigate their typomorphic features, such as crystal morphology, trace element composition, thermoelectric properties, and luminescence characteristics, and their implications for ore-forming processes. Pyrite crystals are predominantly cubic in early stages, while pentagonal dodecahedral and cubic–dodecahedral combinations peak during the main mineralization stage. The pyrite is sulfur-deficient and iron-rich, enriched in Au, and relatively high in Ag, Cu, Pb, and Bi contents during the main ore-forming stage. Rare earth element (REE) concentrations are low, with weak LREE-HREE fractionation and a strong negative Eu anomaly. The thermoelectric coefficient of pyrite ranges from −328.9 to +335.6 μV/°C, with a mean of +197.63 μV/°C; P-type conduction dominates, with an occurrence rate of 58%–100% and an average of 88.78%. A weak–low temperature and a strong–high temperature peak characterize quartz thermoluminescence during the main mineralization stage. Fluid inclusions in quartz include liquid-rich, vapor-rich, and two-phase types, with salinities ranging from 10.11% to 12.62% NaCl equiv. (average 11.16%) and densities from 0.91 to 0.95 g/cm3 (average 0.90 g/cm3). The ore-forming fluids are interpreted as F-rich, low-salinity, low-density hydrothermal fluids of volcanic origin at medium–low temperatures. The abundance of pentagonal dodecahedral pyrite, low Co/Ni ratios, high Cu contents, and complex quartz thermoluminescence signatures are key mineralogical indicators for deep prospecting. Combined with thermoelectric data and morphological analysis, the depth interval around 800 m between drill holes ZK3204 and ZK3201 has high mineralization potential. This study fills a research gap on the genetic mineralogy of the Qiubudong deposit and provides a scientific basis for deep exploration.

The Qinhang metallogenic belt is one of the important copper polymetallic metallogenic belts in eastern China. In this belt, many ore deposits host high-grade stratabound copper ore bodies. However, there has been considerable controversy over their origins. The key to the dispute over the origin of the deposits is the lack of precise metallogenic age constraints, which seriously restricts our understanding of the metallogenetic regularity of copper polymetallic deposits in the Qinhang metallogenic belt. To address the controversies regarding the genesis of these types of ore deposits in the Qinhang metallogenic belt, this study focuses on Dongxiang, a representative stratabound, copper-rich deposit in South China. Molybdenum mineralization was discovered through detailed field geological surveys and drilling. This paper reports Re-Os dating for molybdenite in different occurrences for the first time. High-precision Re-Os dating of molybdenite in the Dongxiang deposit shows that the weighted ages of molybdenite in different occurrences are relatively consistent, ranging from 160.4 Ma to 158.7 Ma. The isochron age obtained for all samples is 159.6 ± 0.8 Ma, which is consistent with the weighted mean age of 159.6 ± 0.9 Ma. The hydrothermal apatite, closely associated with the chalcopyrite and bornite mineralization in stratabound copper ore bodies, yielded a lower intercept age of 156.4 ± 1.5 Ma. Zircon U-Pb ages of granodiorite porphyry and granite porphyry are 157.5 ± 0.58 Ma and 153.9 ± 0.63 Ma, respectively. Therefore, the Dongxiang deposit’s rock-forming and mineralization age is concentrated between 160 Ma and 154 Ma. Sulfur isotope compositions of sulfides in stratabound copper ore bodies show a narrow range of δ34S values, from 0.1‰ to 1.85‰, which is consistent with a magmatic origin. Combining Cu-Pb-H-O isotope and previous studies, we comprehensively propose that the Dongxiang is a porphyry-distal hydrothermal Cu-Mo-W polymetallic deposit formed in the Late Jurassic and associated with paleo-Pacific plate subduction. The Qinhang metallogenic belt holds significant potential for porphyry-skarn copper polymetallic deposits, rather than sedimentary exhalative deposits.

Commercial sinter plants are currently exploring the potential addition of high-grade iron ore concentrate in sinter production to improve the sinter grade for sustainable ironmaking. It is known that a significant proportion of ultrafine iron ore concentrates in the sinter blend has a negative impact on the permeability of the sinter bed. Consequently, an adverse effect on the overall productivity of the sinter plant. This study provides an overview of some of the commercially applied sintering technologies installed as countermeasures to the loss of productivity and assesses their capability to accommodate significant proportions of ultrafine iron ore resources. It is noted that retrofitting existing technologies is required to sustain and stabilise the ironmaking process as well as reduce CO 2 emission levels. A conceptual illustration of a sustainable sinter plant is also proposed accounting for these factors.

The global steel industry accounts for 7-8% of global carbon emissions and faces urgent decarbonization challenges due to climate policies and dependence on imported high-grade iron ore. Inspired by flash smelting in copper refining, flash ironmaking technology uses hydrogen to reduce low-grade iron ore (34.5% iron) in 3-6 seconds, thus achieving a paradigm shift away from dependence on coke and achieving near-zero emissions. This study explores the potential market impact of this disruptive technology through historical analogies (e.g., copper industry transformation) and multi-factor analysis. The main findings show that flash ironmaking can enable China to reduce iron ore imports by 50%, reduce energy consumption by 36% (351 kg standard coal/ton vs. 553 kg standard coal/ton), and reduce production costs by 40%, while avoiding carbon tariffs such as the EU CBAM. By enhancing supply chain autonomy and production flexibility, the technology is expected to suppress iron ore prices (from 120 tons to 70 tons) and reduce steel price volatility. However, commercialization risks, such as high hydrogen costs and equipment scalability, may slow market penetration. The study concluded that early adopters, such as Baosteel, may gain cost advantages and green premiums, while traditional blast furnace operators face valuation risks. Policymakers and investors must balance technical feasibility, hydrogen infrastructure construction, and demand-side dynamics to accelerate the low-carbon transformation of the steel manufacturing industry.

Abstract The formation processes underlying super-large gold deposits present a captivating area of study, with a particularly enigmatic aspect being the mechanisms by which gold forms and accumulates within undersaturated hydrothermal fluids, notably in the presence of high-grade, thick ore bodies. To address this issue, we conducted comprehensive mineral textural, geochemical, isotopic, and machine learning analyses on gold ore-related sulfides from the North Sanshandao gold deposit (∼562 t @ 4.35 g/t), which is the second-largest deposit in the world-class Jiaodong gold province, and recognized as China's inaugural super-large offshore gold resource. The deposit is hosted in the Jurassic Linglong granite, and has four stages of alteration and mineralization: (I) quartz-pyrite-K-feldspar, (II) quartz-pyrite-chalcopyrite-native Au, (III) quartz-pyrite-galena-sphalerite-native Au, (IV) ore-barren siderite-ankerite-calcite. Four types of auriferous pyrite were distinguished, including (stage II) porous Py2a and its Py2b overgrowth, and (stage III) Py3a and its Py3b overgrowth. The gold in Py2a occurs mainly in nanoparticles, while Py2b, Py3a, and Py3b contain high content of lattice gold and coarse-grained native gold, with the gold and arsenic contents strongly correlated positively. The characteristics of a porous core and a smooth edge suggest the occurrence of coupled dissolution-reprecipitation (CDR) processes during the early mineralization stage. Low melting point chalcophile elements (LMCE, e.g., Bi, Te, Sb), are frequently associated with gold, indicating that the LMCE melt may play a role in the remobilization of gold, in addition to fluids. Combined with the trace element composition, we show that the CDR process had led to the Au-LMCE liberation and the Au remobilization in the ore-fluid and LMCE melt. This process may have significantly upgraded the ore and formed large visible gold grains and local high-grade ore zone. Mineral geochemistry of stage I arsenopyrite suggests that the mineralization temperature = 300–400 °C (concentrate 342–379 °C), logf(S2) = −11.5 to −6.5 (concentrate −9.5 to −7.5), and logf(O2) = −34.9 to −24.7 (concentrate −30.2 to −26.7). Sphalerite composition suggests that the temperature dropped 320 °C in stage III. Both the North Sanshandao gold deposit (δ34SV-CDT = 10.75–13.31‰, n = 61) and the Jiaodong gold province (δ34SV-CDT (1st and 3rd quartile) = 7.1–10.8‰, n = 1646) have high δ34SV-CDT values, implying that sulfate reduction is a key ore-material source. Our study provides a new model for the widespread development of over 80% of the disseminated-type mineralization in the Jiaodong Peninsula, emphasizing Au remobilization as a key factor for the formation of high-grade and high-tonnage ore zones, and shed new light on the multistage ore-material enrichment in large-scale gold mineralization.

The depletion of high-grade iron ore reserves has increased the need to process low-grade iron ores efficiently. This study focused on improving the iron grade of indigenous laterite ore located at Jhimpir (Thatta district), using gravity and magnetic separation techniques. Mineralogical analysis confirms the presence of goethite, hematite, quartz, calcite, and clay minerals. SEM-EDS mapping shows that silicon (Si) and aluminum (Al) are scattered on the surface of iron-bearing minerals. The stereomicroscopic images showed that the particles below 600 microns are well liberated, but aluminosilicate impurities remain finely interlocked into the iron-bearing minerals. Gravity separation increases the iron content to 53% with a recovery of 35%, while magnetic separation improves the iron content to 58% but with a lower recovery of 25%. The iron content improves further when both methods are used together, but the overall recovery remains low (less than 35%) due to fine impurities within the iron-bearing minerals. These methods are ideal for preliminary concentration, where the goal is to reject coarse gangue and achieve moderate enrichment before using more expensive flotation methods. This research provides valuable insights into optimizing beneficiation methods for the laterite ore. The findings can help develop efficient processes to upgrade low-grade iron ore, making it more suitable for industrial use.

Ore-forming fluid for the formation of banded iron formation-hosted high-grade magnetite ores of the North China Craton: Constraints from pyrite trace elements and sulfur isotopes

Purpose. This work aims to investigate the performance of photocatalyst made from laterite ore to decolorize organic waste of methylene blue. Methods. Laterite ore was processed through leaching in chloride solution, followed by filtration and neutralization using sodium hydroxide to obtain a precipitate that contains maghemite photocatalyst. The maghemite was characterized to ensure its capability as a photocatalyst. The decolorization experiment using methylene blue as a representation of organic waste was conducted in the absence and presence of a photocatalyst in a constant UV light to reveal the mechanism of methylene blue decolorization. Hydrogen peroxide and pH are controlled to optimize the photocatalytic efficiency. Findings. A photocatalyst made from laterite contributes to the significant increase in the decolorization degree of me-thylene blue through the release of hydroxyl radicals, a powerful substance for decomposing organic matter. The optimal decomposition of methylene blue is achieved by combining the increase of hydrogen peroxide and the reduction of the pH of the organic waste. The optimum pH for the decolorization of methylene blue through photocatalytic reaction is at pH = 3. Originality. For the first time, the mechanism of decolorization in the absence and presence of photocatalyst is revealed, resulting an optimum condition to achieved highest degree of methylene blue decolorization. Practical implications. The method for synthesizing photocatalysts can be applied to produce alternative products from laterite ore, especially low-grade laterite ore, a by-product of high-grade nickel ore mining. The optimum conditions revealed in this research can be applied to synthesize photocatalysts from laterite ore and to remediate organic wastes.

Due to the rapid depletion of high-grade iron ores in the world, the iron production from comparatively lower grade iron ores containing higher amount of gangue or higher impurities like phosphorous is now the main focus for the iron and steel industries. The current study has been carried out to understand the distribution and association of phosphorus in a high-phosphorous iron ores from the eastern part of India containing ∼55.4% Fe and 0.56% phosphorous (P). Mineralogical and thermal characterisation studies were carried out by using advanced characterisation techniques like optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, thermogravimetric analysis, differential scanning calorimetry, etc. SEM and electron probe micro-analyser study suggests that iron and alumina-rich gangue minerals are mostly associated with the phosphorous content of iron ore. This high-phosphorous iron ore consists of major phosphorus-bearing phase called berlinite (AlPO 4 ). The gangue minerals (alumina) were found to be principally associated with the phosphorous. The size-wise chemical analysis suggests that the presence of phosphorous increases at finer size fractions, phosphorous mineral liberation is possible at finer size factions for better beneficiation. XRD analysis suggests that phosphorus in iron ores is most likely found as a crystalline phase (berlinite AlPO 4 ) rather than as an amorphous phase and the berlinite phase increases with an increase in the phosphorous level of iron ores.

The growing need for recycling, along with the depletion of high-grade ore concentrates, has led to the inclusion of previously accumulated technogenic materials — such as metallurgical slags, sludge from settling ponds of recirculating water systems, and similar waste – into the charge of primary smelting units. The share of such feedstock in the furnace charge now reaches approximately 25 %, which has resulted in serious technological disruptions to the stable operation of primary autogenous smelting units. In Vanyukov furnaces, this is manifested by the appearance – alongside the typical smelting products (matte and slag) – of a new atypical phase, the so-called intermediate layer. The formation of this layer leads to adverse effects, including the obstruction of flow paths from the furnace hearth to the slag and matte siphons, ultimately causing a complete shutdown of the unit. A sample of this abnormal product, collected from an industrial furnace during a period of process instability, was analyzed using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). These methods allowed the determination of temperature ranges corresponding to phase transformations of the components comprising the intermediate layer. The results obtained can be used to define optimal parameters for stable smelting operation and to develop technical solutions that prevent conditions favorable for the formation of refractory accretions.