Polymetallic Ore Research Articles

Minimizing matrix effect in uranium polymetallic ores by orthogonal non-confocal femtosecond-nanosecond laser induced breakdown spectroscopy

Minimizing matrix effect in uranium polymetallic ores by orthogonal non-confocal femtosecond-nanosecond laser induced breakdown spectroscopy

The imaginaries of the city of Norilsk, from the Soviet industrial utopia to the contemporary nickel legend

Norilsk is a polar city in Russia, located to the South of the Taimyr Peninsula in the Arctic Circle. The city’s surroundings are rich in unique deposits of polymetallic ores, and life in the city is organised around metal extraction. This is a reason why Norilsk is an interesting object for analysis of the social representation of the city’s image. Social representation is a fairly new socio-philosophical concept. By the word ‘representation’ we mean perceptions that are formed on the basis of reality. In the case of Norilsk, it is the result of all perceptions of the city and its environment. The study is based on contemporary documentary films, geographical, historical and journalistic documents. The analysis of perceptions of Norilsk allows us to understand the reasons for ideological debates around the history of Russia, such as discussions about memorials to victims of political repressions. Statements about Norilsk are contradictory. Negative statements are related to negative perceptions of the city, while positive statements are related to the residents’ love for their city. The analysis of representations related to the architecture of Norilsk allows us to identify gaps in the official discourse about the foundation of the city and explore its historical background. The study has revealed that the Soviet architectural heritage is well-preserved and documented, while statements about buildings associated with the Gulag are relegated to a marginalised space. Consideration of external and local representations of Norilsk allows us to understand the process of rewriting the history of the city.

3D modeling of a shallow polymetallic ore deposit using 3D inversion of magnetic, electrical resistivity and induced polarization data: a case study from Nahavand, Hamedan Province, Iran

3D modeling of a shallow polymetallic ore deposit using 3D inversion of magnetic, electrical resistivity and induced polarization data: a case study from Nahavand, Hamedan Province, Iran

Study of material composition and assessment of gravity concentration of oxidised polymetallic ores of RK deposit

Данная работа посвящена изучению вещественного состава окисленных полиметаллических руд и их гравитационной обогатимости. Исследованы три пробы руды и определено, что ценными компонентами в рудах является свинец и серебро. Наиболее сложной пробой является проба №1, т.к. в ней 24,15% (отн.) свинца находится в неизвлекаемой гравитацией и флотацией форме в виде плюмбоярозита. В исследуемых пробах №1 и №2 отмечается довольно высокое содержание первичных шламов (-0,04+0,0 мм), выход которых составил 38,50% проба №1 и 44,70% проба №2. Гравитационное обогащение на отсадочных машинах и концентрационном столе исследованных окисленных проб обеспечивает извлечение крупных свободных зерен церуссита в кондиционный гравитационный концентрат на уровне 44-49%, что будет снижать их переизмельчение перед флотационным обогащением и способствовать повышению общего извлечения свинца Бұл жұмыс тотыққан полиметалл кендерінің заттық құрамын және олардың гравитациялық концентрациясын зерттеуге арналған. Үш кен сынамасы зерттеліп, кендегі бағалы компоненттер қорғасын мен күміс екені анықталды. Ең қиын үлгі №1 үлгі, өйткені ондағы қорғасынның 24,15% (салыст.) гравитациямен және флотациямен бөлініп алынбайтын пішінде плумбоярозит түрінде болады. Зерттелетін №1 және №2 үлгілерде бастапқы шламның едәуір жоғары мөлшері (-0,04+0,0 мм) байқалады, оның шығымы №1 сынама үшін 38,50% және №2 сынама үшін 44,70% құрады. Зерттелетін тотыққан сынамалардың концентрациялық столда гравитациялық байыту церусситтің ірі бос түйіршіктерін стандартты гравитациялық концентратқа 44-49% деңгейінде шығаруды қамтамасыз етеді, бұл флотациялық байыту алдында олардың қайта ұнтақталуын азайтады және қорғасынның жалпы бөліп алынуын арттыруға ықпал етеді This work is devoted to the study of the material composition of oxidised polymetallic ores and their gravity enrichment. Three ore samples were studied and it was determined that the valuable components in the ores are lead and silver. The most diffi cult sample is sample No.1, because in it 24,15% (relative) of lead is in the form of plumboyarosite, which is not extracted by gravity and fl otation. In the studied samples No.1 and No.2 there is rather high content of primary slimes (-0,04+0,0 mm), the yield of which was 38,50% – sample No.1 and 44,70% – sample No.2. Gravity enrichment on jig washer and concentration table of the studied oxidised samples provides extraction of large free cerussite grains in the conditioned gravity concentrate at the level of 44-49% that will reduce their overgrinding before fl otation enrichment and contribute to increase of total lead recover

Potential for the Recovery of Selected Metals and Critical Raw Materials from Slags from Polymineral Zn–Pb Ore Metallurgy—Part I

Slags from the Silesia–Cracow Upland (Poland), including ten historical slags (deposited in waste dumps) and four contemporary slags (from current production), were examined to compare their chemical and mineralogical properties as well as to assess their potential for the recovery of selected metals and critical raw materials. The historical slags associated with the smelting of polymetallic ores originating from Mississippi Valley-type (MVT) deposits consisted primarily of gypsum. The contemporary slags, obtained from industrial waste rich in zinc and lead, were predominantly spinels (magnesium-aluminate and ferric) that exhibited higher iron content (up to 46.6 wt% of Fe2O3) compared to the historical slags (up to 26.1 wt% of Fe2O3). The zinc content was similar for both the slag types (3.5 wt% Zn). The average titanium and arsenic contents in the old and contemporary slags were at the same level as well, with 0.21 wt% (Ti) and 0.13 wt% (As), respectively. The contemporary slags contained higher levels of critical raw materials, such as cobalt, nickel, copper, and manganese, compared to the historical slags. Rare earth elements (REEs) were also more abundant in the contemporary slags, with an average content of 212 ppm, while the historical slags averaged 124 ppm. These findings underscore the potential for recovering valuable metals and critical raw materials from such slags, presenting opportunities for resource optimisation and environmental management.

Environmentally sound geotechnologies for leaching metals from polymetallic ore processing wastes and wastewater

Global challenges (increased consumption of georesources, climatic changes, limited reserves) increase the relevance of the problems of growing waste accumulation and environmentally-sound modernization of mineral extraction. In this regard, the existing approaches to the design of geotechnologies for metal mining need to be improved based on a concept of so-called circulation waste management and ecologization of technological processes. The paper is devoted to the issue of formation of conceptual bases and directions of ecologization of geotechnologies at leaching metals from polymetallic ore processing wastes and wastewater. The study presents recommendations for improving in-situ leaching of ores in blocks, allowing to determine the optimal conditions for increasing the completeness of subsoil use and reducing environmental damage. It was revealed that at metal extraction with solution circulation through brine chambers the content of Na, Cl, SO4 and Ca ions in dialysate was low, while without circulation through brine, it significantly exceeded corresponding MPCs. This proves the fundamental feasibility of controlling natural leaching processes by enhancing the oxidizing potential of natural solvents through the addition of industrial oxidizing agents. It was found that increasing the duration of agitation leaching (both with and without mechanoactivation) leads to a uniform expansion of the local maximums of Pb yield from the pulp when the minimum NaCl concentration decreases from 11–12 to 7% at H2SO4 concentration of 0.6%. One of key results of the study is justifying the expansion of the use of disintegrators to realize targeted activation of tailings. The practical significance of the obtained results lies in the proved feasibility of optimizing the flow sheet of electrochemical extraction of metals from wastewater on the basis of the obtained regularities of the use of brine circulation through brine chambers. In addition, the totality of the obtained results of using a disintegrator for reextraction of lead from geomaterials will allow developing a methodology for calculating the parameters of mechanoactivation action to increase the degree of metal recovery from the tailings of North Ossetia-Alania’s (Zgidskoe, Sadonskoe, Arkhonskoe deposits) polymetallic ores beneficiation. The most promising way for further research is to substantiate methods of using underground space for complete removal of wastes (wastewater and tailings) after their multistage treatment.

Preparation of Titanium Dioxide (TiO<sub>2</sub>) from Waste of Polymetallic Ore Processing <i>via</i> Sulfurization Treatment

Various experimental conditions were applied to extract titanium oxide from the waste of polymetallic ore. X-ray diffraction (XRD) analysis confirms that the waste of polymetallic ore contains including various minerals such as almandine (Fe,Mg,Ca)3Al2Si3O12, brownmillerite (FeAlO3(CaO)2), quartz (SiO2), magnetite (Fe3O4). Using H2SO4 acid with a concentration of 93% in the S/L mass ratio of 1:1.5 at 140 °C is suggested as an optimum reaction condition. Its hydrolysis subsequently leads to the formation of the titanyl sulfate (TiOSO4), and relatively pure titanium oxide is obtained through precipitation and calcination at 600 °C. The observed band gap value of 3.2 eV for the obtained TiO2 corresponds to the typical band gap value of anatase-type TiO2. We calculated the crystallite size of extracted anatase-type titanium oxide according to the Debye-Scherrer equation it was determined to be 96.35 nm. Fully reflecting X-ray fluorescence (XRF) determined that the purity of extracted TiO2 is 93.18%. This report presents a newly developed process that enables the production of relatively high-purity TiO2 (93.18%) from the waste of polymetallic ore (TiO2 5.39%) by a simple sulfurization process.

Fluid inclusions and H–O isotopes of the super-large Nanyangtian tungsten deposit in southeastern Yunnan, southwestern China

The Nanyangtian deposit is a super-large reduced skarn tungsten deposit located in the Laojunshan WSn polymetallic ore province in southeastern Yunnan (SW China). The deposit is represented by three flat-lying mineralized zones formed vertically by the replacement of limestone or minor calcareous schist. The tungsten orebodies are mainly stratiform, lenticular, and vein types, hosted in the Paleoproterozoic Nanyangtian Formation. Three mineral formation stages have been identified based on the mineral assemblages and vein crosscutting relationships (pre-, syn-, and post-ore). The Nanyangtian is a calcic skarn deposit, dominated by a grossular-diopside-tremolite-actinolite assemblage. Scheelite, pyrrhotite, pyrite, and chalcopyrite are the main ore minerals. Detailed petrographic observations show three types of fluid inclusions (FIs) in various hydrothermal minerals: liquid-rich two-phase (type-I), gas-rich two-phase (type-II), daughter mineral-bearing three-phase (type-III). Their homogenization temperatures (193–298 °C) and salinities (1.2–9.3 wt% NaCl eq.) indicate that the Nanyangtian ore-forming fluids were of medium to low temperature and low salinity compared to the statistical data from representative skarn tungsten deposits in South China. Laser Raman microprobe analysis of the FIs shows that the inclusions are dominated by H2O with minor CH4 and N2. The δD values (relative to Vienna-Standard Mean Ocean Water, VSMOW) of fluid inclusions and calculated δ18Owater values (relative to VSMOW) of the fluids in equilibrium with hydrothermal minerals are −105 to −69 ‰ and − 1.9 to 7.6 ‰, respectively. These oxygen–hydrogen isotopic compositions indicate that the ore-forming fluids were magmatic-derived, which may have metasomatized the Nanyangtian Formation carbonaceous calcareous rocks along interlayer structures to form the prograde skarn minerals. Then the fluids mixed with meteoric water migrated along faults to form the retrograde skarn and tungsten ore. Mixing of magmatic fluid with meteoric water is likely the main factor for the ore precipitation at Nanyangtian.

A Study on the efficiency of organic activator application to process refractory hard-to-beneficiate raw materials

Polymetallic ores with complex mineralogical compositions pose significant challenges in flotation beneficiation, often resulting in suboptimal separation and recovery of valuable minerals. This study aims to analyse the effectiveness of alkyl benzene sulfonic acid (ABSA) as a frothing activator in improving the flotation performance and mineral recovery of polymetallic ore. It presents the results of flotation beneficiation experiments for polymetallic ore of complex mineralogical composition. Experiments were conducted on polymetallic ore samples using ABSA as the frothing activator in the flotation process. The performance was evaluated based on recovery rates and separation efficiency, comparing the results with standard floating frothing agents. The findings showed the highest efficiency of ABSA application for samples of mixed-type ores in increasing the recovery of gold, copper, zinc and lead in the collective concentrates of flotation beneficiation. ABSA activator promotes additional cleaning of fragments containing valuable metals from oxide films and coatings and the transfer of valuable metals' microparticles due to the organics' adsorption properties and the formation of metal-carbon bonds. Another effect of using this reagent is there was an increase in concentrate mass yield while maintaining the quality parameters. A similar effect was observed for beneficiation of copper ore with complex composition - copper recovery in the main concentrate increased. Selective flotation with the development of gold concentrate from hard-to-beneficiate polymetallic ore also showed a significant increase in gold recovery with ABSA pretreatment.

Reinforced co-leaching of REEs/Nb/Ti from low-grade concentrate mixture: Decomposition behavior and co-leaching mechanism

Baerzhe ore deposit is rich in such critical elements as rare earth elements (REEs), niobium (Nb), and titanium (Ti). However, in this ore, the REEs/Nb/Ti-bearing minerals are interlocked closely and thus not easily liberated and separated from each other by mineral processing methods. In order to achieve high recoveries of these critical elements, a concentrate mixture of REEs/Nb/Ti minerals can be obtained through gravity/magnetic separation and flotation to discard most of the gangue minerals. And then the Fe2(SO4)3-H2SO4 roasting and H2O leaching of REEs/Nb/Ti from the concentrate mixture by hydrometallurgical method was investigated in this work. The results showed that Nb/Ti-bearing minerals convert to Nb2O4SO4/TiOSO4 in the H2SO4 roasting process and then readily hydrolyze to Nb(OH)5/Ti(OH)4 in the H2O leaching process. When Fe2(SO4)3 is introduced into the H2SO4 roasting process, the solubility and leaching efficiency of Nb/Ti increases significantly by the generation of soluble Fe-Nb/Fe-Ti sulfates and coordination-enhanced leaching of sufficient SO42−. REEs-bearing minerals are still converted to RE2(SO4)3 in the Fe2(SO4)3-H2SO4 roasting, achieving co-leaching of REEs/Nb/Ti during H2O leaching. Under optimal conditions, with a roasting temperature of 300 °C, a mass ratio of H2SO4 to concentrate mixture of 1.0 g/g, a roasting time of 3 h, a mass ratio of Fe2(SO4)3 to concentrate mixture of 0.1 g/g, a leaching temperature of 40 °C, and a leaching time of 3 h, the co-leaching efficiencies of REEs, Nb, and Ti reached 97.76 %, 87.97 %, and 90.82 %, respectively. This new method improves the recovery of REEs/Nb/Ti with good selectivity and relatively low cost, providing a new idea for the efficient exploitation and utilization of low-grade polymetallic ore.

Metal bioaccumulation and translocation potential of three herbal plant species at mine tailings

Phytoremediation as a technique for cleaning soil contaminated with potentially toxic metals uses plants that can absorb them, and then translocate and accumulate them in above-ground parts. Its effectiveness depends on the selection of adequate plants. Therefore, this study aimed to investigate the potential of three wild herbaceous plant species (Holcus lanatus L., Agrostis alba L., and Eupatorium cannabinum L.) growing on mine tailings for phytoremediation applications. The content of selected metals in soil and plant samples was determined by flame atomic absorption spectrophotometer. The research results indicate that the content of Pb and Cu in the soil of the rhizosphere of the studied species was higher than their remediation values, after the exploitation of polymetallic ore (lead-zinc-copper), which made the tailings an ecological hazard. The species H. lanatus proved to be a good candidate for the phytoaccumulation of Cr, and the species A. alba of Ca, while the species E. cannabinum proved to be phytoaccumulator of all tested metals in the researched mine tailings. Potential for phytoextraction applications were shown by the species H. lanatus for Cd, Cu, Mg and Ni, and A. alba for Cd and Zn.

3-D spatial distribution of concealed ore-forming granitoid intrusion and structures determined by the CSAMT survey of Wuxu Sb-Zn-polymetallic ore district, South China

Wuxu ore district is an important lead-zinc-antimony polymetallic ore field within the Danchi metallogenic belt of South China. Although previous geochemical studies have indicated that the deposit type is medium to low-temperature magmatic-hydrothermal, the existing metallogenic models remain controversial due to the thick covering layer and lack of exposure of granitic bodies. To address this issue, this study utilised four CSAMT parallel profiles across the Wuxu anticline to perform two-dimensional inversion, yielding high-resolution subsurface resistivity models. By comparing the resistivity anomalies along the regional strike shown by the profiles and integrating geochemical and ore deposit structural analyses, a detailed geological interpretation was conducted. A significant high-resistivity body beneath the core region of the Wuxu anticline is interpreted to be the Yanshanian period granitic intrusion. There are westward- and eastward-dipping high-conductivity belts existing within the western and eastern wings and appear to sandwich the inferred high-resistivity code of the Wuxu anticline, respectively. They may represent the deep faults extending underground and are the result of decoupling of lithological interface within the anticline and thereby rock fracturing. The high-conductivity feature may be the result of filling with high-conductivity saline fluids, and possible hydrothermal alteration. The regional compression stress during the Caledonian period and the early Yanshanian period promoted the formation of the anticline and rock fracturing of both wings of the anticline. After that, the regional extension background of the late Yanshanian period made the fault zones reactivated, becoming the site and channels for magmatic intrusion, upward transporting of hydrothermal fluid and alteration, causing lead-zinc-antimony polymetallic ore formation. The exposed ore deposits above may also corroborate this view point. In summary, our resistivity model visually depicts the spatial distribution of the granitic intrusion controlling ore formation and major structures such as anticlines, fault zones, and hydrothermal alteration zones in the 3-D space, providing new geophysical constraints for solving the controversy over the metallogenic model for Wuxu ore district.

In-situ geochemical and isotopic analyses of multiple pyrite generations: Insights for the giant Beiya Au polymetallic ore genesis in southwestern China

The Beiya giant Au polymetallic deposit is located in the Sanjiang Tethyan Orogen, northwestern Yunnan (SW China). The ores occur as disseminations or veinlets in granite porphyry. To unravel the ore genesis at Beiya, we analyzed the ore-related sulfide trace elements and sulfur isotopes. Py-1 is mainly euhedral-subhedral medium-/coarse-grained (size: > 100 μm), with relatively smooth surface and some pores. Py-2 is mostly coarse grained (size: 50–200 μm), with well-developed pores and inclusions. The pyrite is usually Co-Cu rich and V-Ti-Sb poor, resembling typical magmatic-hydrothermal pyrite. In addition, the Co/Ni ratios decrease from pyrite-1 (Py-1) to pyrite-2b (Py-2b), suggesting that their chemical compositions are controlled by magma fractionation. We found that Co, Ni, As, and Se occurred as solid solution in the pyrite lattice, while Pb, Bi, Ag, and Mn occurred mainly in inclusions in the pyrite. Pb and Bi display good positive correlation, suggesting that they occurred as inclusions or nano-particles in pyrite lattice. The pyrite samples have sulfur isotope value (δ34S) of 0.62–3.45 ‰ (avg. 2.35 ‰) for Py-1, 0.18–3.12 ‰ (avg. 1.85 ‰) for Py-2a, and 0.62–4.18 ‰ (avg. 2.51 ‰) for Py-2b. These characteristics may have played a vital role in the initial enrichment of Cu, Mo, Au, and ultimately formed the complex polymetallic system at Beiya.

Совершенствование реагентных режимов флотации руд сложного вещественного состава

Pyrite copper-zinc (sulfide) and polymetallic ores in Russia are complex and rebellious mineral raw materials. The main processing technology for such ores is flotation. Enhancement of the flotation technology for such mineral raw materials is currently performed in several directions. The practice of copper-zinc ore processing proves that obtaining highquality zinc and pyrite concentrates is impossible without the use of various modifiers in the sphalerite and pyrite flotation process. Such reagents are copper (II), zinc and iron (II) sulfates in the alkali-calcic medium. Therefore, research was carried out to study floatation properties of sphalerite and pyrite in the alkali-calcic medium with addition of one of the indicated sulfates to the mineral flotation process. The effect of each of the sulfates of copper (II), zinc and iron (II) on the flotation properties of sphalerite and pyrite was studied during flotation of the mineral with butyl xanthate and dithiophosphate at pH equal to 8, 10, and 12. The aim of this work was to study the effect of the sulfhydryl collectors in presence of copper sulfates, zinc and iron for flotation of sphalerite and pyrite with the grain-size class of 0.074 + 0.044 mm from one of the Russian deposits.

STUDY OF THE PROPERTIES OF MODIFIED BINDER OBTAINED ON THE BASIS OF BENEFICIATION WASTE OF THE MINING AND PROCESSING PLANT

The introduction of active mineral additives into cement makes it possible to obtain concrete with high physical, mechanical and operational characteristics, namely, they increase the density, water resistance, frost, sulfate, alkali resistance and salt resistance of concretes and mortars, while reducing the consumption of clinker cement. The scale of construction of facilities using cement concrete is growing every year, which raises the question of reducing the consumption of clinker cement, due to the high energy intensity of production using active mineral additives. The use of active mineral additives in the form of waste from enrichment has high economic and environmental significance. The article examines the ways of using waste tailings of polymetallic ore enrichment in cement as a complex modified binder with an active mineral additive. To select the optimal ratio of silica and Balkhash GOK enrichment waste, their pozzolan activity was determined, which is 3.8-4 times higher for silica than for BGOK waste. The pozzolan activity of Balkhash GOK enrichment waste 16 hours after mixing with lime solution is 24 mg/g, and microsilicon is 114 mg/g. The pozzolan activity of a complex mineral additive for cements consisting of 60% of Balkhash GOK enrichment waste and 40% of microsilicon is 48 mg/g. The introduction of 40% silica into the Balkhash GOK enrichment waste increases the pozzolan activity of the complex additive by 2 times. This made it possible to obtain a modified binder using a complex mineral additive of up to 20%.

Анализ эквивалентности трехмерных моделей при 3D-интерпретации данных аэроэлектроразведки

The article is devoted to the problem of the equivalence of three-dimensional geoelectric models obtained as a result of 3D-interpretation of aerial electrical survey data in medium where local conductive bodies are covered by a heterogeneous near-surface layer. To carry out the research, we used data from aerial electrical prospecting carried out in the Creighton area (Canada) when searching for polymetallic ores. A two-stage 3D-inversion was used to build the geoelectric model. The purpose of the first stage of 3D-inversion was to reconstruct near-surface structures based on survey data obtained at the early times. The second stage of 3D-inversion was based on the residual map constructed from the practical signals and the signals obtained after the first stage of 3D-inversion at later times. Using the residual map, the starting positions of local bodies under the overlying layer were specified, and their geometry and properties were obtained during local 3D-inversions. Based on the results of 3D-inversion, a local conductive body was identified and confirmed by drilling data. An equivalence analysis was carried out for a three-dimensional model of this body. Various options for initial models differing in the number of blocks describing the body were considered, as well as options for changing the size of blocks in the model obtained as a result of 3D-inversion. It was found that the main equivalence is related to the large distance between flight lines, which is several times greater than the distance between positions on the profile. Therefore, most equivalent models are characterized by a decrease in the size of blocks in the direction orthogonal to the profiles, due to an increase in their size along the profile and a change in resistivity. At the same time, according to the criterion for drilling wells, the resulting equivalent models were identical, i.e. from a geological point of view, no fundamental difference was found between the resulting equivalent models.

Influence of Mineralogy and Mineralogy Approach to Optimize Processing: A Case Study of Tin–Copper Polymetallic Ore

Tin-Copper polymetallic ore is a type of typical ore that cassiterite is closely associated with sulfide minerals. In mineral processing of tin–copper polymetallic ore, flotation is generally used to recover valuable sulfide minerals, while gravity separation is used to recover cassiterite. A mine in Yunnan, China, uses the traditional “flotation–gravity separation” process to recover copper and tin but faces several problems during processing, such as an insufficient copper grade in Cu concentrate, a much higher grade of As in S concentrate, and a grade of S in Sn concentrate that exceeds the standard. A process mineralogy study was conducted, with a focus on Cu–S mixed concentrate, S concentrate, and Sn rough concentrate. It was determined that the main cause of these problems is not the liberation or size distribution of valuable minerals but the superstructure of pyrrhotite, which represents one of the most abundant minerals in the products. Based on EMPA, SEM-EDS, and XRD data, both monoclinic pyrrhotite and hexagonal pyrrhotite occurred in all samples. The abundance of different superstructures of pyrrhotite in one sample was determined by means of particle extraction and area calculation from microscopic images, and the distribution characteristics of monoclinic pyrrhotite and hexagonal pyrrhotite in the whole process were clarified. This process mineralogy study indicates that the strong magnetic hexagonal pyrrhotite mainly affects the copper recovery during flotation, and the hexagonal pyrrhotite mainly affects the recovery of cassiterite during gravity separation. Strong magnetic monoclinic pyrrhotite and weak magnetic hexagonal pyrrhotite should be fully considered in the optimization of mineral processing, and the magnetic separation of pyrrhotite should be adopted to optimize the overall environment of copper flotation and tin gravity separation.

Green approach for separating iron and rare earths from complex polymetallic solid residues via hydrogen-based mineral phase transformation: A pilot-scale study

The Bayan Obo low-grade polymetallic ore (BOLPO) has been abandoned for many years owing to its difficult beneficiation and remains as a solid residue. This is causing significant ecological damage to the surrounding environment. In this pilot-scale study, hydrogen-based mineral phase transformation (HMPT) technology and associated equipment were used to successfully separate iron and rare earths from BOLPO, demonstrating stable operation for 48 h. Optimal HMPT conditions included a feed rate of 120 kg/h, HMPT temperature of 500 °C, gas flow rate of 3.5 m3/h and gas concentration of 22.5 vol%. After grinding and flotation defluorination, the obtained iron concentrate had a TFe grade of 65.26 wt%, a recovery of 85.29 wt%, and a low F grade of 0.28 wt%. Product analysis revealed phase transformations of iron and rare earths during the HMPT process, which increased the magnetic difference between the magnetic and non-magnetic products. The formation of pores and cracks during this process also facilitates the subsequent separation of iron and rare-earths. This study paves the way for clean and efficient iron and rare earth separation with regional mineral recovery potential.

Two periods of magmatism in the Weishancheng ore concentration area, Henan Province: Evidences from zircon U‐Pb chronology, Hf isotopes and petrogeochemistry

The Weishancheng area of Tongbai County, Henan Province, is an important Au‐Ag polymetallic ore concentration area in China, characterized by a widespread distribution of plutons and frequent magmatic activities. To investigate the genetic relationship between magmatism and the mineralization of gold and silver polymetallic deposits in the area, this study focuses on the porphyritic monzogranite of the Liangwan pluton and the biotite granite of the Taoyuan pluton in detail. The zircon U‐Pb age of the Liangwan pluton is 128.5 ± 0.7 Ma, placing its intrusion age in the Early Cretaceous. Similarly, the zircon U‐Pb age of the Taoyuan pluton is 431.3 ± 2.7 Ma, indicating an intrusion age in the Early Silurian. Petrogeochemical analysis reveals that both the Liangwan and Taoyuan plutons exhibit high SiO2, Na2O and Al2O3 contents, along with low MgO, Fe2O3 and CaO contents, indicating a (high‐K) calc‐alkaline series, and have the properties of peraluminous I‐type granite. The total rare earth elements (REE) concentrations are low, with noticeable fractionation between light and heavy REE, and a negative Eu anomaly. High‐field‐strength elements (such as Nb, Ta, P, Ti) are depleted, while the large‐ion lithophile elements (such as Rb, K, Pb) are enriched. The εHf(t) values of the Liangwan and Taoyuan plutons range from −16.1 to −18.8 and from 11.0 to 14.6, respectively. The mean values of Hf two‐stage model ages (TDM2) are 603 Ma and 2230 Ma, respectively. These results suggest that the Liangwan pluton may have formed through partial melting of ancient crustal materials in the Palaeoproterozoic, during extensional tectonic events following the subduction of Izanagi Plate. It appears closely linked to Au‐Ag mineralization in the ore concentration area. The Taoyuan pluton likely originated from the depleted mantle and experienced some degree of crustal contamination. However, it is unrelated to regional mineralization.

Mineralized structures from the Alhué mining district, Chile: Using fluid inclusions and textures

The Alhué mining district (AMD) of the Coastal Range in Central Chile is situated approximately 70 km southwest of the city of Santiago and hosted in stratified Jurassic and Early Cretaceous sequences which are common in central Chile. More than 79 faults and veins are recognized in the AMD hosted in andesites and tuffs with clear structural control showing two distinct trends. Precious‐metal mineralization locally extends over strike lengths of up to 1000 m along these structures with grades averaging at 5 ppm gold and 23 ppm of silver. In this study, a University of Chile – YAMANA GOLD joint research project was created to better understand this particular deposit and explore the origin of gold anomalies found in the district using drill core, mine, and surface samples. Wide internal variations in homogenization temperature and electrolytes were observed at all scales: on the district scale, in mineralized structures intersected in drill core, and in hand specimens. This variability may reflect the diversity of ore-forming conditions in the mining district in addition to the different processes (including fault motion over time) and geochemical components within the district. Textural analyses and fluid inclusion assemblages (FIA) provide evidence for boiling and flashing mechanisms at several localities. Raman spectroscopy and LA-ICP-MS techniques allowed a better characterization of the fluid composition and mineral paragenesis. The presence of gold (∼3.8 ppm) and silver (∼1424 ppm) in both vapor-rich only FIAs (i.e. that contain 99 % vapor) hosted in quartz and liquid-rich FIA hosted in sphalerite implies that gold was transported as sulfide and chloride complexes. The AMD shows a transition from a high temperature environment (sometimes containing calc-silicate minerals) to a low temperature (epithermal) system. This mineralization depended on the type of vein system which tend to be mineralized in strike slip faults e.g. Maqui and Lorena structures. The consequence of flashing documented at dilational jogs, structural intersections and fault bends was likely an important outcome leading to the precipitation of metals at the AMD.Coexisting liquid-rich and vapor-rich fluid inclusions contained in a FIA were observed at the deepest levels in the Chilco vein and the proportion of samples showing boiling increases with depth, indicating that additional precious metal resources may be present below current exploration depths. In summary, our new results reveal that gold, silver and base metal veins found at the AMD in Chile are unique hydrothermal polymetallic ore deposits that are structurally controlled and related to an orogenic environment. A general model for the AMD is one where high temperature fluids from deep crustal mafic magmatic systems, probably as products of a devolatilization and far-from-equilibrium conditions, reach subsurface conditions along faults and are mineralized along these faults. Because having a truly unique ore deposit in the geologic record is very unlikely, the AMD forms an important case study that helps understand structurally controlled ore deposits. Thus our work can form a model for future exploration in the AMD and provide insight into exploration in other sites in Chile and along continental margin settings worldwide, in both poorly characterized known deposits and at greenfield sites.