Ore Minerals Research Articles

PRISMA Hyperspectral Remote Sensing Data for Mapping Alteration Minerals in Sar-e-Châh-e-Shur Region, Birjand, Iran

Remote sensing satellite imagery consistently provides valuable and frequent information, enabling the exploration of mineral resources across immense, remote and harsh domains. Recent developments in spaceborne hyperspectral remote sensing have opened avenues to support diverse remote sensing applications, particularly in the realm of mineral exploration. This study evaluates the capabilities of the PRecursore IperSpettrale della Missione Applicativa (PRISMA) hyperspectral satellite data for mapping alteration minerals using the Matched Filtering Unmixing (MFU) approach in the Sar-e-châh-e-shur, Birjand, Iran. Minerals such as richterite, augite, psilomelane, ilmenite, kaolinite, smectite, mirabilite, muscovite, and chlorite were identified using the vertex component analysis (VCA) technique. Subsequently, alteration mineral maps of the study area were generated using a matched filtering technique. Additionally, through the integration of X-ray diffraction (XRD) analysis, thin section examination, geochemical study of stream sediments, and interpretation of geological maps, potential alteration mineralization zones were delineated in the study area. Ultimately, the validation process, which included comparing the maps with the findings derived from the PRISMA remote sensing study, was conducted using the normal score equation. Thus, our results yielded a normalized score of 3.42 out of 4, signifying an 85.71% agreement with the regional geological characteristics of the study area. The results of this investigation highlight the substantial potential of the PRISMA dataset for systematic alteration mineral mapping and consequent exploration of ore minerals, specifically in challenging and inaccessible terrains.

Mineralogical and geochemical constraints on the origin of alunite and APS minerals from advanced argillic alteration systems: A case study from Kuh-e-Lakht Au-Ag-Cu mineralization, NE Isfahan, Iran

A significant association of alunite supergroup minerals commonly associated with quartz and pyrite is found in the Kuh-e-Lakht district of NE Isfahan, Iran. These minerals occur as pervasive alterations and within hydrothermal quartz veins. Based on field observations, microscopic studies, and geochemical analyses, the alunite subgroup exhibits noticeable variations in morphology, composition, and geochemical signatures between areas with moderate to high mineralization and those with poor mineralization. Poorly mineralized regions contain aluminum-phosphate-sulfate (APS)-free minerals of the alunite subgroup formed from steam-heated acid or supergene processes at an estimated temperature of about 200 °C, with a higher K2O than Na2O content. These crystals exhibit pseudocubic or acicular habits and zoned formations with rhythmic bands and lack APS minerals. Moderately to highly mineralized areas in Kuh-e-Lakht host tabular to platy and bladed alunite subgroup crystals with a hypogene origin, formed at around 250 °C, characterized by a higher or equal Na2O content compared to K2O. These areas also feature APS minerals with different modes of occurrence. In the southwestern, north-central, and northwestern parts, a strong genetic link with high-sulfidation minerals like pyrite, enargite, and chalcopyrite is observed. Alunite subgroup crystals with the highest Na2O/K2O ratio or equal values, as well as APS minerals with svanbergite-woodhouseite composition, occur within alunite crystals or as individual euhedral crystals exhibiting complex oscillatory zoning. These characteristics confirm a close association with the ore formation period and also the influence of higher-temperature fluids with magmatic-hydrothermal components, likely originating in closer proximity to intrusive sources. The estimated temperature for the alunite subgroup and associated ore minerals in these areas falls in the range of approximately 250 °C to 300 °C.

Mechanical Properties and Sulfate Freeze–Thaw Resistance of Calcium Carbonate Whisker-Reinforced Iron Ore Tailings Concrete

Iron ore tailings from iron ore mines pose environmental challenges. However, their reuse could provide significant environmental benefits. This study focused on producing clean concrete using iron ore tailings as crushed stone aggregate (IOTA) and calcium carbonate whiskers (CWs) as reinforcement. Five mixture groups were prepared: normal concrete (NAC) with natural crushed stone aggregate (NA), iron ore tailings concrete (TAC) with IOTA, and CW (10%, 20%, and 30%)-reinforced TAC (TAC-CW). Mechanical properties like the compressive strength (fcu) and splitting tensile strength (fst), as well as sulfate freeze–thaw (F-T) cycle resistance, were thoroughly investigated. Additionally, pore structure and microstructure were characterized using nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM) techniques. The results showed that IOTA’s complete replacement of NA decreased concrete mechanical properties and frost resistance, but incorporating CWs effectively compensated for these losses. Specifically, the fcu and fst of TAC-CW20 with 20% CWs increased by 23.26% and 49.6% compared to TAC and were higher than those of NAC. With increasing F-T cycles, concrete internal pore structure significantly deteriorated, and corrosive products increased significantly, which was further confirmed by SEM. TAC-CW20 significantly optimized pore structure. Overall, the successful application of iron ore tailings as eco-friendly materials enhanced concrete performance and reduced the environmental impact of construction activities.

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.

Geochemical characteristics and mapping of Reşadiye (Tokat-Türkiye) bentonite deposits using machine learning and sub-pixel mixture algorithms

Reşadiye bentonite deposits, which play a significant role in Türkiye's bentonite production, are situated in Central Anatolia. Geochemical, mineralogical, and remote sensing data have been integrated to map the spatial distribution of clay minerals in the bentonite deposits and argillic areas. It is hypothesized that the bentonite samples occurred by the in-situ diagenetic alteration of rhyolite-dacite, trachyte, and andesite/basaltic andesitic composition pyroclastic rocks (ash-flow tuff). Biotite, clinoptilolite, calcite, dolomite, K-feldspar, opal-CT, quartz, and clay minerals are detected in most bentonite samples. The clay patterns determined in the bentonite samples in the X-ray diffraction (XRD) diagrams were 12.3–12.6 Å and were interpreted as being rich in Na-smectites. Mineral mapping in these deposits is essential for mining operations since the high-grade bentonite deposits can be affected by the other clay, gang, and ore minerals they contain in addition to the smectite. The sample spectra measurements matched montmorillonite and kaolin/smectite spectra. This study tests support vector machine (SVM) and artificial neural network (ANN) machine learning and MTMF subpixel algorithms in lithology and mineral mapping in Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite data. It combines the power of subpixel unmixing algorithms to determine the distribution of clay and high-grade bentonites in argillic areas discriminated by machine learning. The results showed that the SVM algorithm can map better than ANN for argillic areas. Additionally, the distribution of high-grade bentonite and kaolin/smectite bearing sites in the study area is discriminated by the mixture-tuned matched filtered (MTMF) spectral classification method. As a result, this study shows that remote sensing studies can be utilized for the exploration and monitoring of high-grade bentonite sites during and/or post-mining operations.

Microanalysis of occurrences of thorium minerals in mica-type ore of the main orebody in the Bayan Obo deposit

Microanalysis of occurrences of thorium minerals in mica-type ore of the main orebody in the Bayan Obo deposit

Ore Elements and Minerals in the Sublimates of Alaid Volcano, Kuril Island Arc

Ore Elements and Minerals in the Sublimates of Alaid Volcano, Kuril Island Arc

Geological setting, lead-zinc mineralization characteristics and its potential prospects in the Na Bop - Pu Sap area, Cho Don, Northeastern Vietnam

The Lo Gam structural zone is recognized as a crucial area for the occurrence of lead-zinc deposits in Northeast Vietnam, encompassing the distinguished territories of Cho Dien and Cho Don. Specifically, within the Cho Don area, the Na Bop-Pu Sap area emerges as particularly noteworthy owing to the considerable scale and quality of its lead-zinc ore deposits. In order to comprehensively investigate the geological attributes and lead-zinc mineralization phenomena prevalent in Na Bop-Pu Sap, a suite of analytical techniques including petrographic analyses, mineralogical examinations, scanning electron microscopy (SEM), and ICP-MS were employed. Furthermore, stable isotope investigations and single mineral sphalerite analyses were conducted to assess the origin of metal constituents and the physicochemical conditions conducive to ore genesis. The Na Bop-Pu Sap area is under the influence of the NW-SE fault system, with the ore structure predominantly manifesting as bands and veins aligned parallel to the foliations of hosted rock. This configuration suggests a close association between the formation of lead-zinc ore and the foliation processes occurring within the shear zones. The assemblage of ore minerals within the region primarily comprises galena, sphalerite, pyrite, pyrrhotite, and arsenopyrite. Integration of S and Pb isotopic analyses alongside single mineral sphalerite assessments reveals that the ore-forming solutions emanate from both magmatic activity and sedimentary sources, with lead-zinc ore deposition occurring at temperatures ranging from low to medium. Projections suggest that the Na Bop-Pu Sap mining area may exhibit relative degrees of erosion extending to depths of approximately 600 meters below the existing terrain surface. This comprehensive examination of the ore characteristics in the Na Bop-Pu Sap mine area yields invaluable insights, thereby advancing our understanding of the potential for deep-seated lead-zinc mineral resources within the Northeastern Vietnam.

Bibliometric and Scientometric Assessment of the Environmental Impact and Sustainability of Open Cast Iron Ore Mining: A Comprehensive Analysis

Bibliometric and Scientometric Assessment of the Environmental Impact and Sustainability of Open Cast Iron Ore Mining: A Comprehensive Analysis

Biomarker signatures and depositional environment of ore-bearing black shale in the Luishia Cu–Co deposit, Democratic Republic of Congo: Implications for regional copper mineralization

The Central African Copperbelt is a globally important sediment-hosted stratiform copper cluster, with regional Cu–Co deposits controlled by Neoproterozoic rift basin. Ore formation in the Copperbelt involves multiple stages of mineralization during diagenesis, basin inversion, and collisional orogeny. Understanding the depositional environment of ore-hosting rocks is crucial for revealing the geological settings and pre-orogenic ore genesis. This paper presents a biomarker study focusing on the ore-bearing black shale in the Luishia Cu–Co deposit, Democratic Republic of Congo. The research investigates thermal maturity, source, and depositional environment of organic matter through rock organic carbon and pyrolysis analysis, chloroform bitumen “A” group component analysis, as well as saturated hydrocarbon gas chromatography-mass spectrometry (GC-MS) analysis. The results indicate significant thermal maturation of organic matter in Luishia black shale. Bacteria are identified as the primary source of organic matter followed by red algae and green algae. The sedimentary environment is characterized by a restricted rift basin under shallow marine conditions with a stratified water column. The processes of bacterial sulphate reduction (BSR) and thermochemical sulphate reduction (TSR) significantly influence the mineralization during diagenesis and basin inversion, respectively. Enhanced thermal maturity promotes methane generation which plays a role in reducing anhydrite and subsequently precipitating ore minerals. The findings have important implications for regional exploration strategies.

Metallogenic model of the Amensif Zn-Pb-Cu-Ag±Au-Bi carbonate replacement deposit (Western High Atlas, Morocco): New litho-structural and mineralogical data

Purpose. In this paper, we discuss the genetic model and emphasize many pending issues on the carbonate replacement textures of the Amensif Zn-Pb-Cu-Ag±Au-Bi deposit (the Western High Atlas, Morocco), the source of metal and the possible contribution of the Azegour granite to this ore genesis. Methods. This study is based on geological mapping, drill core and petrography analysis in combination with ICP-AES, XRD, and SEM data. Findings. The detailed mineralogy consists mainly of sulfides and sulfosalts. The main ore minerals include arsenopyrite, pyrite, sphalerite, chalcopyrite, galena and bismuthinite. Mineral inclusions related to isomorphic sulfosalts are found in galena and/or chalcopyrite. They include matildite, galenobismutite, pavonite, cosalite, schirmerite, krupkaite, ramdohrite, wittichenite, emplectite, luzonite, gustavite, hedleyite, krennerite, wittite, freibergite, tetrahedrite, tennantite and native bismuth. The supergene minerals are anglesite, covellite, malachite, azurite and goethite. In addition, specific replacements are observed between dolomites and sulfides, indicating an interaction between hydrothermal fluid and host rocks. Four ore stages have been identified based on the relationship between mineral phases and ore-forming conditions. The results of this study indicate that Ag and Au precipitation is controlled by the Bi-Te-Pb-S system, while enrichment in Bi, Te and Se sulfosalts and Bi-telluride indicates a magmatic source of the ore-forming fluid. Originality. The study delves into the genetic model of the Amensif Zn-Pb-Cu-Ag±Au-Bi deposit in the Western High Atlas, Moroc-co, with a focus on carbonate replacement textures, while also exploring its classification as either a carbonate replacement deposit or a skarn deposit. Practical implications.Mineral textures are indicators of the replacement process in the Amensif Zn-Pb-Cu-Bi-Ag±Au carbonate replacement deposit (the Western High Atlas, Morocco). The results obtained from this research paper can be used as a powerful tool in mineral exploration of the Western High Atlas.

Lithological and geochemical characteristics and sedimentary environments of the Cambrian high-carbon deposits in the east of the Siberian platform (Kyulenke river basin)

Relevance. The need to study high-carbon deposits as potential sources of hydrocarbons and ore minerals that can significantly increase the mineral resource of Russia. In addition, the analysis of lithological and geochemical features and the reconstruction of the sedimentation conditions of the Kuonamka Formation make it possible to more accurately judge the nature of the Lower and Middle Cambrian paleobasin in the east of the Siberian Platform. Aim. To identify lithological and geochemical features of the composition and determine the sedimentation environment of the Kuonamka Formation. Object. High-carbon deposits of the Kuonamka Formation uncovered by exploration wells on the eastern margin of the Mun arch of the Siberian platform in the Kulenke river basin. Methods. Lithological description of core material; mineralogical and petrographic analysis; X-ray diffraction, X-ray fluorescence and microelement analysis; determination of the content of sulfur and iron forms by wet chemistry; scanning electron microscopy using X-ray spectral microprobe; analysis of petrochemical modules. Results. It was established that the Kuonamka Formation in the studied sections has a consistent structure of four well-defined lithological-stratigraphic horizons. The composition of the deposits is predominantly mixed and is determined by variations in three main mineral groups: clay, carbonate and siliceous, in addition organic matter. The paper demonstrates different forms of organic matter confirming the mixed algal-bacterial genesis of the biocenosis of the Kuonamka basin. The revealed lithological features and lithochemical data indicate the accumulation of high-carbon deposits at a considerable distance from the drift sources in the depression zone of the open sea basin with weak circulation of bottom waters in anoxic conditions. The geochemical euxinic environment was dominant in carbonate-siliceous muds. Sedimentation occurred during one major transgressive-regressive sedimentation cycle being a typical sequence of filling a uncompensated deep depression.

Characterizing low-grade refractory gold ores using automated mineralogy coupled with LA ICP-MS

Researchers have made notable progress in quantifying refractory components causing gold losses in traditional extraction methods. The potential for improving gold recoveries lies in targeted re-treatment of the 'invisible' gold fraction hosted within various ore minerals, even at low concentrations. This study presents a methodology for analysing the refractory components that cause gold losses in traditional extraction methods. The approach utilizes automated mineralogical techniques in conjunction with in-situ laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) to characterize low-grade refractory ores and assess gold deportment. The methodology combines pre-concentration gravity separation, traditional chemical and mineral techniques, and LA ICP-MS to generate comprehensive datasets. To demonstrate the practical application of the methodology, a case study was conducted on historical tailings material from Witwatersrand's Evander Goldfield in South Africa. The case study aimed to determine the mineralogical distribution of gold that cannot be extracted through cyanidation. The results indicated that invisible gold is primarily hosted in pyrite (with an average concentration of 10.21 ppm representing 32 % of total gold), other sulphides (with an average concentration of 1.29 ppm representing 0.42 % of total gold), and oxides (with an average concentration of 0.50 ppm representing 1 % of total gold). The remaining gold is present in discrete fine cyanide amenable phases (with 28 % deportment) and silicate-hosted phases (with 39 % deportment). Environmental monitoring of the Witwatersrand tailings material revealed a net “acid-producing” nature, with high concentrations of heavy metals (such as As, Cu, Pb, Mn, Hg, and Ni) associated with sulphides (with over 78 % deportment). The deportment information obtained through this approach can optimize ore processing strategies and provide valuable insights for future remediation plans. By characterizing the refractory components causing gold losses and understanding the distribution of gold within the ore, this methodology offers the potential to enhance gold recovery and improve the efficiency of ore processing operations.

Porous durian shell biochar modified by KMnO4 (Mn-DSB) as a highly selective adsorbent for Be(II).

The mining of uranium-beryllium ores has resulted in substantial beryllium (Be) contamination. In this study, agricultural waste durian shells were utilized as raw materials to prepare biochar, which was further modified to enhance its adsorption capacity (Mn-DSB). The results effectively demonstrated Mn loading onto the DSB surface. Batch experiments were conducted to identify the optimal adsorption conditions of Mn-DSB for beryllium. At a temperature of 35 °C and pH 6, beryllium's maximum adsorption capacity (Qe) was 42.08 mg·g-1. The materials' internal structure was analyzed before and after adsorption via multiple techniques. Mn-DSB manifested potent selectivity towards beryllium in multicomponent mixed solutions, binary systems, and uranium-beryllium wastewater, as the beryllium removal rate exceeded 90%. The study investigated the recyclability of Mn-DSB and found that after five reuse cycles, the adsorption and desorption efficiencies were 90% and 85%, respectively. The strong ligand complexation (N-H, CO32-, -OH) and ion exchange mechanisms (with Mn7+ ions) of Mn-DSB explained its high adsorption capacity. Therefore, this study demonstrates the potential of Mn-DSB for treating uranium-beryllium tailing wastewater.

Geological structure and metallogeny of Precambrian sedimentary structures of western Aldan-Stanovy Shield

The article presents the results of the study by various geologists of the geological structure and prospects of ore-bearing trog complexes performing structures such as throgs, which were identified at different stages of geological research in the western part of the Aldan-Stanovy shield. The main types of traction complexes and their sections were determined. The nature of the occurrence of sedimentary (terrigenous), volcanogenicsedimentary and metavolcanic rocks performing throgs and forming throg complexes was established. The nature of the ratio of these rocks in the context of the trog complex in the studied trogs was described. The results of the study of trog complexes showed that they are generally characterized by facies variability, heterogeneity of metamorphism and dynamothermal processing of rocks (especially in the sides of trogs) with the formation of mylonites and cataclasites. It was established that the throgs are confined to three regional systems of discontinuous disturbances. Both consonantal and secant discontinuities were marked inside the throgs, defining their block tectonics. The results of determining the geological age of the rocks of the trogovoi complex were presented. The trog structures are characterized by ore mineralization associated with the processes of sedimentation (ferruginous quartzites, copper sandstones) and volcanogenic ore formation (copper-crusted and polymetallic mineralization), as well as with the processes of metamorphogenic-hydrothermal redistribution of ore matter (stratiform scheelite mineralization, ore-bearing quartz veins). It was also found that the metallogeny of the trog structures has not been studied sufficiently. Nevertheless, the majority of geologists who studied the trogovye complexes noted in their reports that Precambrian trogovye complexes can be considered as important and metallogenically promising geological objects in the western part of the Aldan-Stanovy Shield and deserve more in-depth study.

Implikasi Putusan World Trade Organization terhadap Larangan Ekspor Nikel Indonesia oleh Uni Eropa

Indonesia as a member of the World Trade Organization (WTO) is bound by the General Agreement on Tariffs and Trade (GATT) and WTO regulations. In an effort to increase domestic raw material processing, Indonesia implemented an export ban on nickel ore and other minerals. However, this action sparked protests from the European Union, leading to a lawsuit filed with the WTO. This article analyzes the WTO decision in the context of international trade principles, examining its legal applicability in Indonesia and its impact on other types of minerals. The research method used is a normative legal approach or doctrinal research. The final decision of the WTO dispute settlement panel declared that Indonesia's policy of export bans and mandatory processing of nickel minerals violated Article XI.1 of the GATT 1994. Nevertheless, Indonesia appealed the decision and remains committed to the nickel ore export ban to advance the economy and welfare of its people. Thus, this policy represents a bold step towards downstream the mining industry.

Collaborative separation of nickel and iron from nickel laterite ore and red mud

ABSTRACT In this study, we investigated a nickel laterite ore with Ni content of 1.56 wt% and a red mud with Fe content of 20.98 wt%, the main Ni-bearing mineral in the nickel laterite ore was nickel-lizardite, and the main Fe-bearing mineral in the red mud was hematite. A novel process of roasting and magnetic separation was purposed to extract nickel and iron from the nickel laterite ore and red mud. The nickel laterite ore, red mud, calcium chloride, and coke were mixed and put in a roaster for roasting, and the ferronickel concentrate was obtained from the roasted ore by magnetic separation. The results showed that a ferronickel concentrate with Ni content of 7.97 wt%, Fe content of 73.09 wt%, iron recovery of 76.87%, and nickel recovery of 90.28% was obtained under the optimal conditions: a mass ratio of m (nickel laterite ore): m (red mud) : m (coke) : m (calcium chloride) : of 0.6:0.4:0.2:0.1, a roasting temperature of 1373 K, a roasting time of 90 min, a grinding fineness of − 0.045 mm occupying 90%, and a magnetic field strength of 0.20 T. The main minerals in the ferronickel product were metallic Fe and FeNi.

Formation of Intergrowths of Platinum-Group Minerals and Gold from Magmatogenic Ores in Relation to Phase Changes in Pt-Pd-Fe-Cu-Au System

The article discusses the features of the chemical composition and the formation of intergrowths of platinum-group minerals, gold, gold-bearing phases, and other ore minerals present in placers collected from the Anabar River in the northeast part of the Siberian platform. Based on an analysis of changes in the phase compositions of these intergrowths of noble metals with other ore minerals on (Pt, Pd)-Fe-Au and Pd-Cu-Au phase equilibrium diagrams, potential trends in the crystallization of natural polymineral alloys from multicomponent low-sulfide metallic liquids are discussed. The similarity of the microstructures of natural and metallurgical alloys indicates that the formation of natural multiphase Au-PGE intergrowths occurred in a similar manner to the crystallization of multicomponent synthetic alloys. The authors suggest that magmatic Au-PGE mineralization occurs during the crystallization of a noble-metal-containing, low-sulfide, Cr-rich oxide melt separated from silicate mafic–ultramafic magma. Magmatic gold–platinum deposits are commonly associated with sulfide or oxide disseminated-schlieren ores in layered mafic–ultramafic intrusions. However, due to the high solubility of gold and platinoids in sulfide minerals, PGMs in sulfide ores occur as isomorphic impurities or as microphases and dispersed inclusions that cannot form placers. Therefore, the authors suggest that magmatic Au-PGE mineralization occurs during the crystallization of an immiscible low-sulfide, high-Cr oxide liquid separated from silicate mafic–ultramafic magma. In the northeast part of the Siberian platform, potential sources for these placers are likely alkaline, high-Ti mafic–ultramafic intrusions, as confirmed by the presence of silicate inclusions in ferroan platinum similar in composition to melteigite.

Adding Agricultural Topsoil and Growing Perennial Ryegrass (Lolium perenne L.) Enhanced the Rehabilitation of Metal/loids Enriched Iron Ore Mine Tailings

Revegetating iron-ore mine tailings is difficult due to their poor physicochemical and microbial properties. This experiment aimed to improve tailings properties for better plant growth and rhizosphere activities. First, a pot experiment was conducted to assess the influence of topsoil amendment on the remediation of tailings collected from two sites (coded A and B) in Western Australia to promote the growth of perennial ryegrass (Lolium perenne L. cv Ausvic). Each pot was filled with pre-defined ratios of topsoil to mine tailings (0, 10, 20, 30, 50 and 100% w/w). Perennial ryegrass was harvested 60 days after sowing and analysed for plant growth, root morphological characteristics and metal uptake by shoots. Second, a study on biological attributes and an incubation study over 84 days were carried out. The addition of topsoil significantly decreased pH, but EC and total organic carbon (TOC) increased with an increased proportion of topsoil. Total concentrations of As, Co, Cr, Cu, Ni, Pb, Zn, Fe and Mn decreased with an increased ratio of topsoil in growth medium. The highest root dry biomass was observed in the treatments with 30% and 50% topsoil addition to tailings, whereas shoot dry biomass only increased with 50% topsoil. Total root length increased significantly with 50% topsoil addition to site A tailings. A significant increase in microbial biomass carbon (MBC) was found with 50% addition of topsoil compared with the control. Microbial quotient (MBC/TOC) decreased significantly with the addition of topsoil to both types of tailings. Metal contents in perennial ryegrass shoots decreased with the increasing rate of topsoil, but perennial ryegrass was an effective phytoextractor of Cu, Zn and Mn. Further, the incubation study revealed that 50% topsoil application increased cumulative respiration emissions in both A and B tailings after 42 days. Iron ore mine tailings can be improved in terms of physicochemical and biological attributes by adding topsoil. However, further investigation should be carried out to determine the speciation of metal/loids in amended iron ore tailings.

Health risk assessment of soil heavy metals in a typical mining town in north China based on Monte Carlo simulation coupled with Positive matrix factorization model

The accumulation of heavy metals (HMs) in soil caused by mineral resource exploitation and its ancillary industrial processes poses a threat to ecology and public health. Effective risk control measures require a quantification of the impacts and contributions to health risks from individual sources of soil HMs. Based on high-density sampling, soil contamination risk indexes, positive matrix factorization (PMF) model, Monte Carlo simulation and human health risk analysis model were applied to investigate the risk of HMs in a typical mining town in North China. The results showed that As was the most dominant soil pollutant factor, Cd and Hg were the most dominant soil ecological risk factors, and Cr and Ni were the most dominant health risk factors in the study area. Overall, both pollution and ecological risks were at low levels, while there were still some higher hazard areas located in the central and south-central part of the region. According to the probabilistic health risk assessment (HRA), children suffered greater health risks than adults, with 21.63% of non-carcinogenic risks and 53.24% of carcinogenic risks exceeding the prescribed thresholds (HI > 1 and TCR>1E-4). The PMF model identified five potential sources: fuel combustion (FC), processing of building materials with limestone as raw materials (PBML), industry source (IS), iron ore mining combined with garbage (IOG), and agriculture source (AS). PBML is the primary source of soil HM contamination, as well as the major anthropogenic source of carcinogenic risk for all populations. Agricultural inputs associated with As are the major source of non-carcinogenic risk. This study offers a good example of probabilistic HRA using specific sources, which can provide a valuable reference for strategy establishment of pollution remediation and risk prevention and control.