Ore Types Research Articles

Big data mining on trace element geochemistry of sphalerite

The determination of ore genesis is a main challenge in ore deposit research. Advanced and rapid analytical techniques have given rise to the accumulation of massive amounts of geoscientific data. Therefore, it is imperative to conduct data mining on ore geochemical data to efficiently extract useful metallogenic information. In this contribution, 4095 sets of sphalerite trace element data from 86 deposits of different origins (VMS, MVT, porphyry, epithermal, SEDEX, and skarn) were compiled and analyzed. Factor analysis revealed the effects of physicochemical conditions on sphalerite trace element compositions. Specifically, the high Mn-Fe-Cu-Co-In but low As-Ga-Ge-Sb-Pb concentration of sphalerite is commonly related to decreasing pH or increasing temperature; high sulfur fugacity favors the entry of Fe and Co (but not Ga or Sn) into the sphalerite lattice; and high salinity causes enrichment in Cd-Ga-Ge-Mn, but depletion in Ag-Cu-In-Sb. Multivariate statistical analysis reveals that the Mn-Ge-Sn contents in sphalerite have good potential to differentiate among ore genetic types, the Mn-Ge-In are used to determine between magmatic-hydrothermal and non-magmatic-hydrothermal deposits. Furthermore, machine learning models demonstrate high accuracy of sphalerite trace element data in distinguishing ore types, i.e., 93.02 % (random forest) and 92.82 % (gradient boosting), and its reliability was validated by receiver operating characteristics. Additionally, the blind tests by machine learning on sphalerite trace elements indicate that the Qingshuitang deposit (in the Qin-Hang metallogenic belt, South China), have been an MVT deposit, which is also supported by its low-temperature and high-salinity fluids, wallrock alterations (esp. bariteization), and the obvious age distinction between mineralization and local magmatism. This study highlights that machine learning and multivariate statistical analysis on sphalerite trace-element data can differentiate metallogenic origin and conditions.

Optimizing iron separation and recycling from iron tailings: A synergistic approach combining reduction roasting and alkaline leaching

Iron tailings, a type of refractory iron ores, pose a challenge for effective iron recovery due to the complex mineral combinations and liberation modes. In this study, we proposed a new approach to improve the quality of iron concentrates by combining alkaline leaching with magnetization roasting-magnetic separation, which promoted the leaching of silica and aluminum minerals from iron tailings. We investigated the leaching process conditions, phase transitions, and microstructure evolution of joint magnetization roasted iron tailings in the presence of an alkaline solution. Our research findings showed that with optimal leaching conditions, the iron concentrate from magnetic separation was improved from 59.97 % to 65.07 % in iron grade while maintaining an iron recovery of 92.05 %. The heat and mineral phase transformation during magnetization roasting destroyed the structure of iron tailings particles, resulting in the formation of pores and microcracks that weakened inter-mineral bonding. Additionally, alkaline leaching facilitated the extraction of Si and Al from the structure-damaged iron tailings particles, eliminating 83.75 % of Si minerals and 68.73 % of Al minerals. This study offers a promising solution for iron recovery from refractory iron ores, reduces environmental pollution from tailings, and could enhance current iron recovery technology.

Paleozoic VMS-type stratiform mineralization overprinted by Mesozoic vein-type mineralization in the Yushui copper deposit, eastern Guangdong, South China

The South China hosts a number of stratiform deposit in Late Paleozoic depression, including the Yushui copper deposit (which has a Cu grade up to 53% with an average grade of about 3.5%) in the Yong-Mei-Hui depression. The genesis type of Yushui copper ore is highly controversial due to the influence of post mineralization tectonic and magmatic activities, which affects the exploration of the deposits. Yushui copper deposit is mainly composed of stratiform ore body and stockwork orebody in the footwall, with typical VMS-type deposit characteristics and its mineralization age of 308 Ma. Small amounts of vein-type ore body can also be seen in the hanging wall dolomite of the stratiform ore body, which mainly develops along the joints and faults, and the mineral assemblage includes chalcopyrite, bornite, galena, sphalerite, tetrahedrite, furutobeite, and rare earth minerals (xenotime and bastnaesite). Hydrothermal sericite is also developed when vein-type ore body cut the sandstone in the footwall of stratiform ore body. Pristine euhedral xenotime and bastnaesite crystals from the Yushui Cu mineralized of veins ore body yield LA-ICP-MS weighted mean 206Pb/238U ages of 162.5 ± 6.7 Ma (1 s, MSWD = 11.8) and 164.6 ± 5.3 Ma (1 s, MSWD = 9.5), respectively. Hydrothermal sericite yields a plateau 40Ar–39Ar age of 163.19 ± 7.60 Ma, which is consistent with the xenotime and bastnaesite U–Pb age, suggesting that the vein-type Cu mineralized is generically related to the Middle-Late Jurassic hydrothermal event. These ages indicate that in addition to the major Late Paleozoic mineralization events that formed VMS-type stratiform ore body, there were also small-scale hydrothermal vein-type ore body formed during the Middle and Late Jurassic mineralization events that did not cause major disruptions to the earlier stratiform ore body. Combining with the chronological research of other copper deposits in the southeastern coastal area of China, this article believes that these 170 ∼ 155 Ma deposits were all due to the crust-mantle interaction caused by changes in the subduction angle of the ancient Pacific plate. Our study suggests that the southeastern margin of the South China has potential for the exploration of polymetallic hydrothermal mineralization related to Middle-Late Jurassic magmatic rock.

Mineralogical and spectral characteristics of Changbai jade, Jilin province, Northeast China

Changbai jade is a type of jade ore with good economic value that is found in the tuff of the Upper Triassic Changbai Formation of the Mesozoic period in Jilin Province, China. However, the mineral composition of the kaolinite group in Changbai Jade has not been definitively identified, and there has been a lack of systematic mineralogical and spectral analysis. To analyze the mineralogical and spectroscopic characteristics of Changbai jade, this study utilized several modern testing methods, including X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), Fourier transform infrared absorption spectroscopy (FTIR), Raman spectrum test (Raman), and Ultraviolet visible (UV-vis). Mineralogical and spectroscopic analyses were conducted on Changbai jade ore samples CB21 and CB22. The results indicated that the main metamorphic minerals of the two samples are dickite and the color-causing factor of the yellow part is pyrite. This research provides basic theoretical research data for jade processing technology and the geological origin of Changbai jade.

Mineralogie sulfidických rud z Měděné štoly ve zlatohorském rudním revíru

Until 1993, sulfide ores of copper, lead and zinc, as well as native gold were mined in the Zlaté Hory ore district in the Jeseníky Mountains. These deposits occur in the Devonian volcano-sedimentary complex of the Vrbno Group, which consists of quartzites, phyllites, limestones and metamorphic igneous rocks of intrusive and extrusive nature. The main ore bodies are located in a quartzite horizon containing lenses of felsic metavolcanic rocks or in the underlying and overlying rocks (mainly phyllites). Sulfide mineralization of the Měděná Adit in the Zlaté Hory ore district concentrated in greenschists containing three mineral assembblages: i) chlorite + quartz + albite + barian feldspar + siderite + dolomite (ankerite) ± ilmenite, ii) chlorite + phlogopite + quartz + albite + siderite + dolomite (ankerite) ± magnetite ± ilmenite, iii) chlorite + muscovite + quartz + albite + ilmenite ± siderite ± magnetite. Micas have elevated barium contents (2.2 to 5.5 wt. % BaO in phlogopite, 2.6 to 4.6 wt. % BaO in muscovite) and represent the dominant carrier of this element in the rock. In the case that mica is absent in the rock, barium is bound in barian feldspar. When content of quartz in these greenschists is high, they pass into quartzite. Three types of sulfide ore were found in the Měděná Adit: A) banded copper ore in biotite-chlorite greenschist, which is formed dominantly by disseminated pyrite and pyrrhotite, accompanied by a small amount of chalcopyrite (the ore contains approx. 0.7 wt.% Cu), B) disseminated copper mineralization in quartz-rich bands or quartzite intercalations in chlorite greenschist, consisting mainly of pyrrhotite, less voluminous pyrite, and small amounts of chalcopyrite and galena (the ore contains approx. 0.3 wt.% Cu, the lead content is highly variable, up to 0.15 wt.% Pb), C) vein-like copper ore in greenschist with chalcopyrite dominating over pyrrhotite and pyrite (the ore has a very high copper content, 13.6 and 24.7 wt.% Cu in two analyzed samples). With its mineral composition, structural features and the character of the ore-bearing rocks, disseminated copper mineralization is similar to the Cyprus-type ores (so-called Cu-pyrite ores). The vein copper mineralization is probably a result of copper remobilization during regional metamorphism.

Quantifying the relationship between particles' strength and their mineralogical and textural characteristics

Advances in ore characterisation methods, such as automated mineralogy and core scanning technology, as well as in the breakage characterisation field, suggest that the relationship between the ore characteristics and its comminution behaviour can be thought of differently. This study focuses on developing a relationship that allows the transformation of the quantitative characterisation of rock particles (i.e., mineralogical and textural measurements) into particle strength. This study characterised ten different ore types using quantitative methods (i.e., SEM-based technologies and image analysis). At the same time, the strength of particles was collected from physical specimens tested in the SILC over a limited range of particle sizes (3 to 16 mm). The analysis of the databases shows that none of the characteristics has total control over the strength of particles. However, the shape of the grains and the contrast of the physical properties of minerals that compose the particles seem to be more significant in predicting the particles' strength of these rocks. In addition, the model was more successful in predicting particle strength for most rocks with more regular grain sizes, indicating that this parameter requires further comprehension.This research shows that ore characterisation data has the potential to be used to predict the strength of rocks' particles up to a millimetre scale, which is relevant to comminution, which would allow a direct link to be established between the plant and ore characteristics at the particle scale. However, more experimental and numerical studies are needed to develop a predictive and generalised model from quantitative ore characterisation data that may allow improving the modelling of the comminution stage by incorporating more resolution to the system and reducing the laborious work of comminution testing, helping to optimise the whole size reduction process.

The impact of coal mine dust characteristics on pathways to respiratory harm: investigating the pneumoconiotic potency of coals.

Exposure to dust from the mining environment has historically resulted in epidemic levels of mortality and morbidity from pneumoconiotic diseases such as silicosis, coal workers' pneumoconiosis (CWP), and asbestosis. Studies have shown that CWP remains a critical issue at collieries across the globe, with some countries facing resurgent patterns of the disease and additional pathologies from long-term exposure. Compliance measures to reduce dust exposure rely primarily on the assumption that all "fine" particles are equally toxic irrespective of source or chemical composition. For several ore types, but more specifically coal, such an assumption is not practical due to the complex and highly variable nature of the material. Additionally, several studies have identified possible mechanisms of pathogenesis from the minerals and deleterious metals in coal. The purpose of this review was to provide a reassessment of the perspectives and strategies used to evaluate the pneumoconiotic potency of coal mine dust. Emphasis is on the physicochemical characteristics of coal mine dust such as mineralogy/mineral chemistry, particle shape, size, specific surface area, and free surface area-all of which have been highlighted as contributing factors to the expression of pro-inflammatory responses in the lung. The review also highlights the potential opportunity for more holistic risk characterisation strategies for coal mine dust, which consider the mineralogical and physicochemical aspects of the dust as variables relevant to the current proposed mechanisms for CWP pathogenesis.

Quartz-Hosted Fluid Inclusions in Commercial Ores of Various Type at the Verninskoe Gold Deposit, Bodaibo District, Russia

The paper presents data on quartz-hosted fluid inclusions in commercial ores of various type (veinlet−disseminated and vein) of the Verninskoe gold deposit. The ores of various types were found out to significantly vary in the values of some of their physicochemical parameters of the fluids and in the composition of these fluids. The fluids that formed the gold veins have a somewhat higher initial temperature (356–246°C), a higher density of carbon dioxide in gas inclusions (1.00–0.84 g/cm3), and a higher fluid pressure (3170–1390 bar) than those of the fluids that formed the veinlet–disseminated ores (330–252°C, 0.87–0.54 g/cm3, and 1960–570 bar, respectively). The fluids that formed the gold veins were enriched in CО2, Sr, Ag, Ga, Ge, Mn, Fe, Ni, Sn, Ba, and REE, whereas the fluids that formed veinlet–disseminated mineralization were richer in HCO−3, Br, Sb, V, and Au. This situations may be explained by the interaction of the deep fluid with the terrigenous host rocks in the course of ore deposition. When vein quartz crystallized in relatively wide fractures, the fluid interacted with host rocks and changed not as much as when the veinlet−disseminated ores were formed in narrow fractures. The initial parameters of the fluid that formed the vein quartz were thus the closest to the characteristics of the fluid that transported the ore components, and the comparison of these data with the parameters of the fluids that formed the veinlet–disseminated mineralization demonstrates that they changed in the course of ore deposition. The mineral-forming fluids likely came from a deep-sitting source, and the mineral-forming processes may have involve granitoid-derived fluids.

Quartz-Hosted Fluid Inclusions in Commercial Ores of Various Type at the Verninskoe Gold Deposit, Bodaibo District, Russia

Quartz-Hosted Fluid Inclusions in Commercial Ores of Various Type at the Verninskoe Gold Deposit, Bodaibo District, Russia

Textural and chemical evolution during dedolomitization: A case study of the Benassal Formation, Maestrat Basin, Spain

The process of dedolomitization (dolomite calcitization) has been the subject of several studies, but the mechanisms that control it are still not fully understood. Dedolomitization, i.e. the replacement of dolomite by calcite, is an important diagenetic process that affects dolostones, in certain cases decreasing the local porosity and altering the rock mechanical properties, reservoir quality and fluid flow pathways. In this contribution we report the petrographic and geochemical evidence of the progressive dedolomitization and its impact on the Lower Cretaceous dolostones of the Benicàssim area (Maestrat Basin, Spain) that host Mississippi Valley Type (MVT) ore deposits. Textural observations and geochemical data suggest that replacement was induced by the interface coupled dissolution-precipitation mechanism. Moreover, quantitative chemical content measurements with mass balance calculations show that dedolomitization caused a ∼5% gain of mass during the reaction, associated with 5 vol% of solid volume increase. The lack of microfracture development suggests that the compensation of such volume increase is achieved by microporosity being filled during calcite precipitation. Considering the meteoric origin of the dedolomitizing fluids, the mass balance calculation allows estimating the element mass transfer during the reaction. The fact that the fluid was enriched in Zn supports that the fluid was acidic, and likely percolated through the local MVT deposits. Calculation of the required volume of the reactive fluid (102–104 m3/m3 dolostone) also shows that thermodynamic calculations overestimate the volume of fluid. This study shows the importance of quantifying mass transfer in diagenetic conditions to better understand metasomatic processes and constrain the fluid pathway in the basin history. As a societal impact, this diagenetic process releases ∼11% of the carbon mass but seems to preserve all rare earth elements.

THE IMPACT OF KOKONAO STOCKPILE MATERIAL ADDITION WITH SUPER GRADE ORE MIXING MATERIAL TO THE CONSENTRATE CONTENT AND ALOY RECOVERY IN COPPER ORE FLOATATION PROCESS AT THE PT. FREEPORT INDONESIA

PT. Freeport Indonesia is one of the mining companies that process copper and gold ore. One type of ore processed in this company is Super Grade Ore (SGO). The characteristics of SGO are wet and smooth, which can result in some problems in transportation. Therefore, it is necessary to do the blending process using material from the Kokonao stockpile which tends to be drier and rougher but has a lower grade than the Cut of Grade of company. Applying the experimental method, this research aims to figure out the effects of the addition of Kokonao material in the blending process with SGO on concentrate grade and metal recovery results. Overall, the levels of Cu and Au reduce when the Kokonao material is added to each various composition, with the lowest Cu grade being 100% Kokonao (1,97%) and the highest Cu grade being 10% Kokonao (25,69%). Meanwhile, the lowest Au grade is 100% Kokonao portion (3,26 ppm) and the highest Au grade is 20% Kokonao (38,16 ppm). In addition, All various compositions result in Cu recovery that is higher than the company standard (>80%). The highest Cu recovery is the result of 50% Kokonao composition (97,12%).

Fractal analysis of the sulfide composition and structure of interspersed ores in picrite gabbro-dolerites of the Oktyabrsky deposit, Norilsk ore field

The analysis of ore samples taken from wells drilled on the Eastern flank of the Oktyabrskoye deposit was carried out. In the vein-disseminated sulfide copper-nickel ores of the deposit, three types of mineralization are distinguished, which clearly differ from each other: interstitial-teardrop-like, interstitial, tear-shaped-interstitial. A sample of each type of ore was examined by 3D tomography and analyzed using fractal theory. Based on the results of the study, a conclusion was made about the relationship between the fractal dimensions of ore minerals and the dynamics of the formation of various types of ores. The pattern of changes in the intensity of mineralization from the thickness of the layers is established. The results obtained may be of great importance in relation to the technology of enrichment of new types of ores from the flanks of the deposit, and also be an additional criterion for identifying in disseminated ores zones with the highest intensity of ore mineralization during prospecting and exploration in the Norilsk ore region.

Evolution, Magmatic Source and Metallogenesis of A-Type Granites in the Fanchang Volcanic Basin, Middle and Lower Yangtze Metallogenic Belt: A Review

The Fanchang volcanic basin (FVB) is located in the Middle and Lower Yangtze Metallogenic Belt (MLYMB) between the ore districts of Ningwu and Tongling. The existing ore deposits in the FVB are relatively small in scale and related to late Mesozoic A-type granites. In this paper, the crystallization age, major and trace element composition, and Sr-Nd and Hf isotope compositions of the A-type granites are summarized from the literature; in addition, the magnetite composition, H and O isotopes of fluid inclusions, and sulfur isotope composition of metal sulfides in some typical ore deposits in the FVB are also summarized to give insights into the petrogenesis and mineralization of the A-type granites intruding into the FVB. The results show that: (1) Orthopyroxene, plagioclase, K-feldspar, and biotite are the main fractionating minerals controlling the evolution of the magmas of A-type granites in the FVB and other areas in the MLYMB. (2) The whole-rock Sr-Nd and zircon Hf isotopic characteristics show that the source of A-type granite magma is complex and includes the enriched mantle, lower crust, and upper crust, probably with stronger participation of Archaean–Paleoproterozoic crustal materials in the FVB granites than in other regions of the MLYMB. (3) The ores in the FVB are dominated by skarn and hydrothermal deposits. H and O isotopes of fluid inclusions indicate that ore-forming fluids have been derived from mixtures of magmatic hydrothermal fluid, meteoric waters, and deep brine related to gypsum layers. S isotopes of metal sulfides indicate that the sulfur may be a mixture of magmatically derived sulfur and sulfur originating from the Triassic gypsum-bearing layers. The deposit and ore characteristics of the main deposits in the FVB are also illustrated, and the evaluation of metal resources indicates that the skarn and hydrothermal iron–zinc ores in the FVB also have potential as sources of Cd, Ga, and Se. In addition, in terms of the oxygen fugacity, rock type, and geochemical characteristics of magmatic rocks, the metallogenic characteristics and potential of the A-type granites in the FVB are evaluated. It is considered that in addition to the dominant constituents of iron and zinc and the minor constituents listed above, the FVB could have the potential for providing copper, gold, molybdenum, uranium, and other metals as well.

ЭКСТРАГЕНТСОДЕРЖАЩИЕ МИКРОЭМУЛЬСИИ КАК НАНОСТРУКТУРИРОВАННЫЕ СРЕДЫ ДЛЯ ВЫЩЕЛАЧИВАНИЯ ЦВЕТНЫХ МЕТАЛЛОВ

A method for extracting metals from solid phase particles using extractant-containing microemulsions is proposed, and its features are studied on a model system with CuO. It is shown that the microemulsion leaching method is suitable for the extraction of non-ferrous metals from various types of ore and secondary technogenic raw materials, and extractant-containing microemulsions based on sodium bis-(2-ethylhexyl)phosphate and sodium dodecyl sulfate are promising functional nanomaterials for hydrometallurgy.

Low-temperature oxidation of sulphide ores of sulphide-polymetallic deposits of Azerbaijan


 
 
 The article presents the results of experimental studies to determine the oxidative ac- tivity for the main industrial types of sulphide ores of sulphide-polymetallic deposits in Azerbai- jan. To calculate the amount of heat generated during oxidation, the dependences of the oxygen absorption rate on the temperature and moisture of the ore were established. It was found that with an increase in temperature above 50-80oC, absorption of oxygen slows down with time faster than at low (2.5-50oC) temperatures. If with an increase in temperature from 2.5 to 45-50oC the amount of absorbed oxygen increases by 7.5-12 times, then at a temperature from 45-50oC to 80oC it increases only by 3.6-3.7 times, which is explained by a decrease in moisture of the ore with an increase in temperature, due to evaporation. The time dependence of absorption rate of the oxygen for sulphide ores of sulphide-polymetallic deposits of Azerbaijan has a clearly pronounced break, which indicates a change in the oxidation mechanism. The oxidizing activity of sulphide ores of sulphide-polymetallic deposits of the Balakan ore field of Azerbaijan at low temperatures (2.5-800C) was studied. Determination of the oxidative activity of the main industrial types of sulphide ores of sulphide-polymetallic deposits in Azerbaijan makes it possible to classify ore reserves according to the degree of tendency to spontaneous combustion, which will allow a scientifically sound approach to planning the sequence of their development and designing mines. In addition, the article presents the results of experimental studies to determine the oxidizing activity of the sulfide ores of the Katsdag, Filizchay and Katekh deposits, carried out in laboratory conditions by the method of Institute of Mining named after A.A. Skochinsky. An indicator of oxidative activity is the oxygen absorption rate constant and labeled by the letter U (ml/g hour). The results of laboratory studies show that the oxidation of the ore leads to an increase in temperature and ignition and depends on a large number of factors such as mineralogical composition, chemical activity, humidity, temperature, fragmentation, etc. The dependence of the total amount of oxygen absorbed by sulphide ores on time at various temperatures is obtained. It has been estab- lished that with increasing temperature, the rate of oxygen absorption by sulphide ores increases. The values of the temperature coefficient (Kt < 2.0) in the temperature range of 2.5-800C show that the rate of the oxidation of sulfide ore is controlled by oxygen diffusion, and not by the rate of the chemical reaction. With equal fragmentation and equal distribution of chemical elements in ore samples, the oxidation rate is directly proportional to the outer surface of the sulphide ore.
 
 

Study of spontaneous combustion of the main industrial types of sulphide ores of sulphide- polymetallic deposits of Azerbaijan


 
 
 The article is devoted to the study of the causes and conditions of spontaneous com- bustion of sulphide ores, which may result in endogenous fires that complicate mining operations in mines, causing enormous material damage to the national economy, and often also leading to human casualties. There are several sulphide-polymetallic deposits in Azerbaijan, the reserves of which were approved back in the days of the USSR. Of these, the Filizchay deposit is the most unique in terms of its reserves and ore composition. The development of other deposits adjacent to the Filizchay deposit, separately, is inexpedient because of their small reserves. However, the development of sulphide-polymetallic deposits in Azerbaijan is complicated by the revealed tendency of industrial types of ores to oxidation and spontaneous combustion. In this regard, there was a need for a special study of the chemical activity of sulphide ores and the phenomena accompanying oxidative processes, taking into account the natural features of the deposits in order to obtain the initial parameters necessary for scientifically based technological solutions for their development. Sulphide ores of sulphide -polymetallic deposits of Azerbaijan significantly differ in material composition, conditions of occurrence and mining technical features of their development from the listed deposits, the issues of spontaneous combustion of which have been studied for a long time. Until now, there are no general criteria for assessing the fire hazard of sulphide ores, suitable for any deposit, since the conditions for the occurrence of underground fires at different deposits are different. It is this circumstance that makes it necessary to conduct special studies for each deposit separately. Therefore, the need for a special study of this problem on the example of the conditions of sulphide-polymetallic deposits in Azerbaijan, which are prone to oxidation and spontaneous combustion, is of great importance. Identification of causes and factors affecting spontaneous combustion of sulphide ores, classification of sulphide-polymetallic deposits of Azerbaijan according to the degree of their tendency to spontaneous combustion by analyzing the collected materials, as well as by the results of studies to determine the oxidative activity of sulphide ores. The article presents the results of experimental studies to determine the oxidative activity and spontaneous combustion of sulphide ores of the Katsdag, Filizchay and Katekh deposits, carried out in laboratory conditions by the method of Institute of Mining named after. A.A. Skochinsky, the basis of which is the determination of the oxygen absorption rate constant. It is known that the susceptibility of ore to spontaneous combustion is determined by its oxidizability at low temperatures and depends on a large number of factors. In this regard, the dependence of the total amount of oxygen absorbed by sulphide ores on time has been studied, it has been established that the rate of oxygen absorption by sulphide ores is long-live and slowly fading, but incessant. On the basis of extensive experimental material, a classification of sulphide ores of Azerbaijan according to the degree of tendency to spontaneous combustion according to low-tempera-ture oxidation is proposed, since it is this that forms the basis of the spontaneous combustion process. The classification is also based on differences in textural and structural features and mineralogical composition of ores. Of great interest is also the influence of the size of the free reacting surface of the ore on the oxidation process. Analysis of ore samples shows that for their spontaneous combustion, the most dangerous are its coarse fractions than the dust. The results of the conducted studies allow a scientifically sound approach to planning the sequence of development and designing mines.
 
 

Textural-structural characteristics and mineral types of ores of the Aghlig-Filfilli mineralization area of the Duruja zone


 
 
 The black shale complex, which is organic carbon-bearing and characterized by syngenetic, epigenetic sulphidation and intense metamorphism in the Duruja structural-forma- tion zone of the southern slope of the Greater Caucasus, is the focus of geologists’ attention due to the mineralization areas, which are rich in significant non-ferrous, noble, radioactive metals, rare and rare earth elements. In order to determine the prospects of noble, non-ferrous, radioactive metals, rare and rare earth elements of the black shale of the Aghlig-Filfilli mineralization area of the Duruja zone, it is necessary to determine the mineralogical composition of the ores of the area, to study the textural-structural characteristics and to clarify whether the rocks of the zone are a source of complex ore raw materials. The object of the work is the mineragraphic and petrographic study of the numerous samples col- lected from the Aghlig-Filfilli mineralization area during the field expedition before the PhD admission period, during my post-graduate studies and currently in order to solve various important mineralogical and petrographic problems. In order to investigate the textural-structural characteristics and mineral types of the ores of the Aghlig-Filfilli mineralization area, thin sections and polished sections made from the samples were studied with the help of «Carl Zeiss» and «Polam-312» microscopes in transmitted and reflected rays. The composition, surface area and morphological characteristics of the monomineral samples were studied by the electron microscope «SEM». Accurate diagnosis of some minerals was carried out based on the results of their X-ray diffractometric analysis. According to the results of the research, the ores of the Aghlig-Filfilli mineralization area were formed in 3 stages: syngenetic, epigenetic and rem- ineralization as a result of strong metamorphism of syngenetic formations. At the same time, the origin of the ores of the Aghlıg-Filfilli mineralization area was studied. According to the results of the research, it was determined that epigenetic mineralization in contact with Aralig and Zangi deep faults in the north and south of the Aghlig-Filfilli area is of magmatogene origin (δ34S=1.6-4.6), and synge- netic mineralization in the black shales towards the center is of biogenic origin (δ34S= -18 – -22.6).
 
 

Thermodynamic Calculations of Direct Reduction Smelting Technology of Copper Oxide Ores Based on Smelting Slag from the Yubeidi Site, Yunnan Province

The current research on metallurgical remains from scientific excavations in northeast Yunnan from the Bronze Age period is insufficient. In order to study the smelting technology of the Bronze Age in north-eastern Yunnan, samples of slag and mineral excavated from the Yubei Di site in Dongchuan were examined. Based on the outcome of the characterization analysis, a simulation was executed utilizing the software Factsage 7.1 in order to generate a phase diagram that accurately portrays the melting procedure. This simulation aimed to produce the most credible representation of the phase transition by employing computational methods. Characterisation methods included Metallographic Microscopy, Scanning Electron Microscopy Energy Dispersive Spectromicropy (SEM-EDS), X-ray diffraction (XRD), and Radiocarbon Date (14C dating). The results showed that there was much copper ore left in the slag of the site. Most of these copper ores were in the form of copper ferrite or cuprous oxide. The copper ore was copper oxide ore, and metal copper particles appeared in a small amount of the slag. Most of the slags unearthed from the site of the Yubeidi site were products of sulfur-containing oxide reduction and smelting into copper. Based on the outcomes of the simulations, it was established that the slag excavated from the Yubeidi site was mainly from the reduction and smelting process of sulphur-containing copper oxide minerals into copper, without consciously adding fluxes, not having mastered the slag-making techniques for different types of copper ores, and with primitive techniques. The carbon 14 dating results show that the age of the slag was during the Spring and Autumn Period and the Warring States Period.

Characterizing a new type of nelsonite recognized in the Damiao anorthosite complex, North China Craton, with implications for the genesis of giant magmatic Fe-Ti oxide deposits

Abstract Nelsonite (Fe-Ti oxide-apatite rock) devoid of silicates offers a rare opportunity to investigate the magma processes for the formation of magmatic Fe-Ti oxide deposits. Both fractional crystallization and silicate liquid immiscibility have been put forward, but the lack of robust evidence has hindered unambiguously distinguishing the role of these two processes in Fe-Ti mineralization. The nelsonite and associated Fe-Ti-P-rich rocks hosted in the Proterozoic Damiao anorthosite complex represent a typical example for studying Fe-Ti ore-forming processes. We recognized a new type of nelsonite (type-I) in the Damiao complex, which is distinct from the two known types of nelsonite (type-II and type-III) from the same complex. The type-I nelsonite is characterized by its coexistence with oxide-apatite gabbronorite and granite in the same dike, and all these rocks have identical emplacement ages (1740 ± 7 Ma), subparallel REE patterns, and major-element compositions lacking intermediate compositions, suggesting derivation from conjugate Fe- and Si-rich melts generated by silicate liquid immiscibility. The large type-II nelsonite bodies form irregular dikes along fractures in anorthosite and constitute the major ore type. The type-III nelsonite occurs as conformable layers or pods within oxide-apatite gabbronorite and pyroxenite, and occupies the end part of the type-II dike. The latter two types of nelsonites formed by extensive fractional crystallization of residual magma with crystal accumulation and subsequent hydrothermal replacement. During residual magma evolution, silicate liquid immiscibility was crucial for Fe-Ti-P enrichment, fractional crystallization was responsible for enhancing oxide-apatite concentrations, and hydrothermal replacement was effective for mobilizing oxide-apatite concentrations. Our newly recognized nelsonite provides an unambiguous, outcrop-scale, field evidence for the operation of silicate liquid immiscibility process. We show that giant magmatic Fe-Ti oxide orebodies can form by a combination of processes involving silicate liquid immiscibility, fractional crystallization and hydrothermal mobilization.

Geochronology and geochemistry of ore-hosted zircon reveal the genesis of typical Sb-(Au-W) deposits in South China

The Xikuangshan and Woxi Sb-(Au-W) deposits are the most important Sb-related mineralization in the Xiangzhong metallogenic province, South China. In this study, trace element, U-Pb dating, and Hf isotopic results of zircon in typical ore samples from the Xikuangshan and Woxi deposits provide new insights into metal/fluid sources and mineralization processes. The zircons in different samples from the Xikuangshan deposit have a similar distribution of zircon U-Pb ages with two major groups: 400–500 Ma and 700–900 Ma, which are consistent with those from their host rocks (Devonian strata) and underlying basement rocks (Lengjiaxi and Banxi Groups). By comparison, the zircons from the Woxi deposit have younger U-Pb ages which are the same as contemporaneous magmatism in South China. The 176Hf/177Hf ratios, εHf(t), and TDM1 further proved an original relationship between the younger zircons (with ages < 500 Ma) and magmatism. The systematic trend in the size and roundness of zircons captured from basement rocks for Xikuangshan might be resulting from gravity separation in the sedimentary process which required a stable and long-lasting mineralization process. On the other hand, the homogenous size and roundness of zircons from the Woxi deposit, regardless of zircon ages and sampling locations, might have been caused by a relatively short and intense mineralization process. The differences in the mineralization process for the two deposits lead to different alteration degrees of zircons and are reflected by the variable concentrations of Y, Hf, Pb, and Th, as well as rare earth elements. In the deposit scale, some samples are considered to be altered at high grade and represent the main mineralization stages for the Xikuangshan and Woxi deposits, as their zircons have variable concentrations of trace and rare earth elements. Combined with previous studies, the sources of zircons and mineralizing material are distinct for the Xikuangshan and Woxi deposits: originated from basement rocks (Xikuangshan deposit) and magmatism (Woxi deposit). In addition, stable and long-lasting deep-circulated meteoric water is considered the mineralizing fluid for the Xikuangshan deposit, whereas the mineralizing fluid for the Woxi deposit might be related to magmatism. This research highlights the use of zircon geochronology and geochemistry in revealing the genesis of Sb deposits, making this method applicable worldwide to similar vein-type mineralization.