Source Of Gold Research Articles

Gold–Rare-Metal Mineralization of the Mokrundya Placer Deposit in Arctic Siberia, Republic of Sakha (Yakutia)

Abstract —The Mokrundya alluvial-placer gold deposit is located in the Verkhoyansk–Kolyma folded region, within the Tuguchak ore–placer cluster. The authors used ore and scanning electron microscopy and chemical–analytical methods to study the typomorphic and mineralogic–geochemical features of gold, minerals of the heavy fraction of the placer, and ore mineralization of the dolerite dike complex stripped in the placer bedrock. Stages of development of the ore-forming system in dolerites have been established. The main productive periods with native gold are associated with the postmagmatic stages: (a) early arsenopyrite–polysulfide stage and (b) gold–bismuth–telluride stage. The latter is composed of bismuth tellurides and sulfotellurides, native gold, bismuth, maldonite AuBi2, and complex Au and Bi intermetallic compounds. The authors hypothesize the sources of placer gold in the alluvial deposits. One of them is the ore mineralization of the dolerite dike complex, and the other is associated with mineralized zones of the Gematitovoe skarn–hydrothermal ore occurrence in the upper reaches of the Mokrundya Stream.

Anthropogenic Source of Gold in Moscow Urban Dust

Anthropogenic Source of Gold in Moscow Urban Dust

Integrated geophysical, remote sensing and geochemical investigation to explore gold-mineralizations and mapping listvenites at Wadi Haimur, Eastern Desert, Egypt

Although the continuity of gold mining work since Pharaonic times till today, Wadi Haimur is still promised source for gold. Wadi Haimur is located in west Allaqi-Heinai-Suture (AHS), south Eastern Desert of Egypt. Gold mineralization is mainly confined within quartz-carbonate and sulphide-bearing quartz veins within sheared, altered rocks, while listvenitization plays a significant role in gold concentration along the Haimur area. Therefore, critical analyses of remote sensing data were applied to map alteration zones and delineate listvenites. Spatially enhanced images were processed to trace lineaments and weakness zones which may represent pathways of mineralized, ascended hydrothermal fluids. Ground geophysical, magnetic and geoelectric surveys were performed to study the depth-extension of mineralized bodies in the vicinity of the historical mines within Wadi Haimur. Interpretation of land-magnetic data indicates the presence of mineralized veins associated with narrow shear zones. Derivatives and high-pass filters were utilized to map shallow mineralized sources and deduce their trends. Upward continuation and low-pass filters were used to detect the deep sources. Depths to magnetic bodies were estimated using Power-Spectrum, Euler and inversion of single anomalies. Geochemical sampling was performed to test the results. According to the remarkable variation in resistivity and chargeability values of resistivity and induced-polarization tomography profiles, the subsurface lithology was classified and probable mineralized zones within the subsurface were detected. Encouraging results from regolith, trenching, rock-chip sampling and Reverse-Circulation (RC) drilling indicated the extension of auriferous anomalies within the bedrock. Good correlation of RC-holes auriferous anomalies depths and deduced depths from magnetic interpretation was revealed. HIGHLIGHTS Integrated geophysical, geochemistry and remote sensing data are used to delineate mineralized ore deposits. The estimated average depths of mineralized sources are 12.5, 48 and 463 m for shallow, intermediate and deep magnetic bodies, respectively. Massive sulphide-bearing zones ± gold concentrations were suggested for zones with low-resistivity and high-chargeability signatures.

Gold Provenance in Placers from Pureo Area, Southern Chile Coastal Cordillera, and Their Relationship with Paleozoic Metamorphic Rocks

Southern Chile placer gold deposits have been known and exploited since Spanish colonial times. Despite this, precise knowledge about their origin is scarce. This work aims to identify possible primary sources of the gold in the Pureo placers by studying the morphological and chemical characteristics of gold particles according to their spatial distribution. The former was determined by measurements and classification under a binocular microscope, allowing us to acquire a set of parameters related to the amount of transport that had affected the samples. The microchemical characteristics were determined by studying gold particles using optical microscopy, scanning electron microscopy (SEM) and electron microprobe (EMPA), where the native gold composition (in terms of major and minor elements) and the suite of mineral inclusions were obtained. The results regarding morphological characteristics suggest a low amount of transport from a primary source (<15 km). Microchemical data from gold particles indicate two compositional sub-populations, distinguished in both native gold composition (<15 Ag wt% with up to 4 Hg wt% and >15 Ag wt% with Hg bellow 1 wt%) and mineral inclusions (pyrite-galena rich and arsenopyrite rich, respectively), indicating two different primary gold sources. These results suggest a local origin of gold in the Coastal Cordillera, where the possible primary sources are associated with (i) massive sulfide deposits present in Paleozoic–Triassic metamorphic rocks and (ii) hydrothermal deposits associated with more recent Cenozoic intrusive activity. These conclusions have implications for the exploration of new placer deposits and of gold-bearing hypogene deposits (e.g., metamorphosed VMS deposits) in unexplored zones of southern Chile Coastal Cordillera.

Gold Particles Recovery using Novel Reducing Agent with Regard to Continuous Approach

Background: Over 300 tonnes of gold utilised in electronics devices every year, end-of-life electronic equipment offers an crucial recycling potential for secondary gold supply. Electronic boards are among common and exploitable sources of gold that are widely used in various industry. The aims of this paper is to use gold element of electronic boards by adjusting its surface functionality and particle size to make this metal to be used in various applications Methods: to gain this purpose by using acidic solutions and up to bottom chemical synthesis method among physical, chemical, and biological methods and by transferring gold particle size from micrometer to nanometer, surface-area-to-volume ratio will be increase such that new structural properties emerge, change, or improve. Results: Tests such as Fourier-Transform Infrared spectroscopy, X-Ray Diffraction, and Field Emission Scanning Electron Microscopy have confirmed high-quality production and proper extraction of gold particles on a nanometer scale from electronic plates and confirmed crystalline structure of extracted gold in range of 70-110 nm. Conclusion: The main objective of this research is to derive and fabricate gold nanoparticles using chemical oxidative route using HCl and Aqua regia to produce gold nanoparticles in Nano dimension scale. Results has shown that gold nanoparticles are synthesized successfully via chemical process. Moreover, Acid concentration and reaction time has enormous effect on production procedure.

New insights into the source of gold in the Youjiang basin, SW China

AbstractMantle plume rich in gold is considered to be important for the formation of giant epigenetic gold deposits. The Youjiang basin, SW China, is the world’s second largest Carlin-type gold province, but the ultimate source of its gold remains enigmatic. In this study, we report that the Middle–Late Permian basaltic rocks in the basin are rich in native gold grains. These gold grains are scattered in the interstices of pyrite and marcasite and in the amorphous silica cavities. Mineralogy and S-Pb isotope geochemistry of the auriferous sulfides suggest that the gold was largely derived from the gold-rich Late Permian (ca. 260 Ma) Emeishan plume and was released to a near-surface volcanogenic massive sulfide (VMS) metallogenic system, where it accumulated. The native gold grains from the basalts may have been inherited by the younger (ca. 140 Ma) Carlin-type ores in the Youjiang basin, which are indicative of gold pre-enrichment in the basin. Our study highlights that golden plume upwelling could carry abundant gold into the upper crust, even into shallow-level metallogenic systems, and thus provides an alternative view on the source of gold in the Youjiang basin.

Potential Uses of Artisanal Gold Mine Tailings, with an Emphasis on the Role of Centrifugal Separation Technique

Few investigations have focused on the potential uses of artisanal gold (Au) mine tailings, despite the fact that artisanal gold mining activity contributes to environmental issues such as greenhouse gas. Mineralogical characterizations of artisanal gold mine tailings in Miyove gold mine (Baradega and Masogwe) in Rwanda were investigated for potential utilization as a source of valuable gold, using the centrifugal separation technique. Results of X-ray diffraction analysis, energy dispersive X-ray spectroscopy, inductively coupled plasma mass spectrometry, inductively coupled plasma–optical emission spectroscopy, and X-ray fluorescence showed that artisanal gold mine tailings samples have significant amounts of gold to justify economical gold extraction opportunity. The gold grades in the ores and artisanal gold mine tailings were in the ranges of 37–152 and 2–7 g t−1, respectively. Quartz was a major phase, with minor impurities in two different types of gold ores and their respective tailings. The beneficiation carried out using centrifugal separation, regarded as an extension of gravity separation, showed gold grades in the range of 535–1515 g t−1 for gold ores and 36–302 g t−1 for artisanal gold mine tailings. The gold recoveries for ores and artisanal gold mine tailings were in the range of 21.8–47.3% and 46.9–63.8%, respectively. The results showed that the centrifugal separation technique was more efficient in boosting gold recovery compared to the present panning approach employed at the site, which sometimes recover as low as 10%. The results suggest that mineralogical characterization of artisanal gold mine tailings allows for the development and design of a suitable methods for improving gold ore beneficiation and artisanal gold mine tailings reprocessing.

О коренных источниках палеороссыпей Витватерсранда (Южная Африка)

The article discusses Witwatersrand paleoplacers as well as current high-mercury gold placers and sources of their formation in the Unya-Bom district of the Amur province. The Witwatersrand deposits contain fine gold with significant mercury content. The original sources are unknown there. In the Unya-Bom district, during the destruction of ore bodies and the transition of high-grade mercuric gold into placers, its composition is preserved, with the exception of the high-grade shell formed in placers: silver and mercury are removed from it due to electrochemical corrosion. When transported in placers up to 25 km, the high content of mercury in the central part of gold particles corresponds to ore gold. An attempt was made to typify one of the possible sources of clastogenic gold in Witwatersrand paleoplacers. It might have been gold-quartz mineralization with high- mercury gold, similar to that common in the Unya-Bom district of the Amur region.

New constraints for crustal sulfur contamination of gold source: Evidence from complex δ34S of pyrite in the northwestern Jiaodong gold province, China

The formation processes of the complex δ34S variations for the Jiaodong-type gold deposits are still equivocal, which cannot give a robust identification for the sulfur sources, by inference, Au sources. The δ34S and trace elements of ore-related pyrite collected from the northwestern Jiaodong gold province (Jiaojia and Sanshandao-Xinli goldfields) are analyzed by in-situ methods, to reveal more clues for understanding the complex δ34S variations and ore material sources. Gold deposits in the northwestern Jiaodong contain quartz-Au-pyrite (Py-a) stage (III) and quartz-Au-pyrite (Py-b)-polymetallic stage (IV). In the Jiaojia goldfield, Py-a has a δ34S range of 9.9–24.4‰, whereas Py-b has a δ34S range of 7.3–9.3‰. In the Sanshandao-Xinli goldfield, Py-a has a δ34S range of 6.9–34.7‰, and δ34S of Py-b ranges in 0.2–19.2‰. Single-point and mapping analyses show that As-Au-Co-Ni contents have considerable variations in Py-a and Py-b. The δ34S and As-Au-Co-Ni contents in Py-a and Py-b show diverse correlations. Equilibrium and Rayleigh (or sulfidation) fractionations cannot account for the large δ34S variation due to the pyrite-chalcopyrite-pyrrhotite buffer. The rapid decompression with oxidization of ore-forming fluids by immiscibility can only result in the δ34S decrease, rather than increase to 14.0–34.7‰ from the concentrated δ34S range of 9.6–13.4‰ in Py-a and Py-b. Therefore, the analyzed δ34S values in the ore-related pyrites should represent those of ore-forming fluids. Considering the simple physicochemical processes cannot reconcile the complex matches between large δ34S variations and As-Au-Co-Ni contents, it is suggested the As-rich and Au-As-rich ore-forming fluids with large δ34S range and variable Co-Ni concentrations should flow into mineralization sites during stages III and IV in the Sanshandao-Xinli goldfield. The sulfur with large δ34S range and Au-As-Co-Ni elements with variable contents in the ore-related pyrites of the Jiaojia and Sanshandao-Xinli goldfields were most likely inherited from the sedimentary sulfides that were reduced from seawater sulfates, by comparisons with those in the typical sedimentary, metamorphic hydrothermal and magmatic hydrothermal pyrites. Combining with previous researches for the ore-forming materials sources of the Jiaodong-type gold deposits, the metamorphic Precambrian rocks, especially those metasedimentary rocks containing sulfides reduced from seawater sulfates, can be considered as the feasible ore-forming materials sources for the large δ34S range and variable trace elements in the Jiaojia and Sanshandao-Xinli goldfields. Through the δ34S comparison for the Jiaodong-type gold deposits, we propose an important process that the single-sourced ore-forming fluids, which were initially derived from the metasomatized lithospheric mantle, have extracted the ore materials (including sulfur-Au-As elements) from the metamorphic Precambrian rocks (possible Precambrian metamorphic basement in the Jiaodong gold province or the subducted Late Neoproterozoic rocks of the YC), and mixed heterogeneously to precipitate pyrites with complex δ34S and trace elements throughout the Jiaodong-type gold deposits.

Study of Lysine and Asparagine as Capping Agent for Gold Nanoparticles

The wide application of gold nanoparticles has attracted much attention to the development of research in gold nanoparticles. In this study, the gold nanoparticles were prepared by chemical reduction method using potassium tetrachloroaurate as the gold source and sodium borohydride as reducer agent. The formation of gold nanoparticles was confirmed by surface plasmon spectra in ultraviolet-visible spectroscopy at wavelength 507 nm. The capping process of gold nanoparticles was studied using two different charges of amino acids. The asparagine had used as uncharge amino acid and lysine as a positive charge amino acid. The redshift in surface plasmon spectra showed the aggregation of the gold nanoparticles after being capped with amino acids that indicates the surface modification. The amine and carboxylate group was present on the gold nanoparticle surface after being capped with amino acids. The zeta potential results indicate the lysine capped gold nanoparticles have slightly higher stability than the asparagine capped gold nanoparticles. These stability and surface modification of gold nanoparticles are expected to increase their utilization on biological and medical applications.

Trace element and S-Pb isotopic compositions of pyrite from the Precambrian metamorphic rocks and their derivative pegmatites in the Xiaoqinling district, southern North China Craton: Implications for possible gold source of the Early Cretaceous gold deposits

The North China Craton is well endowed with numerous Early Cretaceous gold deposits that are mainly hosted in Archean to early Paleoproterozoic metamorphic rocks and late Mesozoic granitoid intrusions intruding the former. Whether or not gold was sourced from those metamorphic rocks remains hotly debated. Here we present trace element and S-Pb isotope data of pyrite from the Neoarchean to early Paleoproterozoic metamorphic rocks in the Xiaoqinling district of southern North China Craton and late Paleoproterozoic pegmatites derived from the former rocks, in an attempt to provide new insights into the gold sources for Early Cretaceous gold lodes genesis in this district. Pyrite from the metamorphic rocks typically occurs as inclusions in rock-forming minerals or disseminated grains roughly distributed along the foliation of the rocks, whereas pyrite from the pegmatites usually occurs as disseminations closely associated with quartz and magnetite. The textural data suggest that pyrite in the metamorphic rocks and pegmatites are of metamorphogenic and magmatogenic origins, respectively. LA-ICP-MS spot analyses show that pyrite both from the metamorphic rocks and pegmatites has Au contents mostly below the detection limit, with minor analyses revealing Au marginally higher than the detection limit. Considering that Au is moderately incompatible and highly siderophile, the very low gold contents in pyrite allow us to infer that the metamorphic rocks contain negligible gold. Pyrite grains from the metamorphic rocks and pegmatites have broadly consistent δ34S values ranging from −2.7 to 31.5 (mean = 17.6) per mil and 6.3 to 17.9 (mean = 14.3) per mil, respectively. Similarly, they have comparable, highly radiogenic lead isotopes, which are 16.859–24.889 for 206Pb/204Pb, 15.355–15.694 for 207Pb/204Pb, and 37.480–43.848 for 208Pb/204Pb. The sulfur and lead isotopes of pyrites from the metamorphic rocks and pegmatites are distinct from those of Early Cretaceous gold deposits hosted by these rocks. Taken together, the pyrite trace element and S-Pb isotope data presented here preclude the Precambrian metamorphic basement rocks as an important gold source for the extensive Early Cretaceous gold mineralization in the Xiaoqinling district and, by inference, other major Early Cretaceous gold provinces across the North China Craton.

Lithospheric conductors reveal source regions of convergent margin mineral systems

The clean energy transition will require a vast increase in metal supply, yet new mineral deposit discoveries are declining, due in part to challenges associated with exploring under sedimentary and volcanic cover. Recently, several case studies have demonstrated links between lithospheric electrical conductors imaged using magnetotelluric (MT) data and mineral deposits, notably Iron Oxide Copper Gold (IOCG). Adoption of MT methods for exploration is therefore growing but the general applicability and relationship with many other deposit types remains untested. Here, we compile a global inventory of MT resistivity models from Australia, North and South America, and China and undertake the first quantitative assessment of the spatial association between conductors and three mineral deposit types commonly formed in convergent margin settings. We find that deposits formed early in an orogenic cycle such as volcanic hosted massive sulfide (VHMS) and copper porphyry deposits show weak to moderate correlations with conductors in the upper mantle. In contrast, deposits formed later in an orogenic cycle, such as orogenic gold, show strong correlations with mid-crustal conductors. These variations in resistivity response likely reflect mineralogical differences in the metal source regions of these mineral systems and suggest a metamorphic-fluid source for orogenic gold is significant. Our results indicate the resistivity structure of mineralized convergent margins strongly reflects late-stage processes and can be preserved for hundreds of millions of years. Discerning use of MT is therefore a powerful tool for mineral exploration.

Geology, mineralogy, geochemistry and conditions of forming the Tukan gold-quartz deposit (Khudolaz trough, South Urals)

Research subject. Detailed mineralogical and geochemical studies of rocks of the Tukan gold-quartz deposit (quartz veins, dolerites, gabbro-diorites) were carried out. The deposit is one of numerous small gold-quartz occurrences in the Khudolaz trough of the West Magnitogorsk zone.Methods. The morphology and composition of native gold was studied using an Axios kop 40 A optical microscope and Tescan Vega 3 and JEOL-6390LV scanning electron microscopes. The chemical composition of rocks was determined by X-ray fluorescence (Carl Zeiss VRA-30) and atomic emission (Shimadzu ICPE-9000) analyzes. Fluid inclusions were analyzed using Linkam TMS-600 thermostage equipped with Link-System 32 DV-NC software and an Olympus BX51 optical microscope. The gas composition of fluid inclusions was examined by Raman spectroscopy (Horiba LabRam HR800 Evolution).Results. Gold-bearing quartz veins and dolerites intersect ing the gabbrodiorite intrusion of the Khudolaz complex are associated with submeridional strike-slip faults. Native gold has a various morphology and is confined to cracks in quartz veins and altered dolerites. The composition of gold is stable, with the average fineness of 871 ± 8.3‰. An analysis of fluid inclusions in a gold-bearing quartz vein showed that gold was formed at temperatures of no less than 186–230°С from a fluid with a salinity of 4–8 wt % NaCl-eq. The presence of gases СО2, N2 and CH4 was found in fluid inclusions. Dolerites and gabbrodiorites hosting gold-bearing veins contain sulfides (pyrite, pyrrhotite, chalcopyrite, pentlandite, violarite), sulfoarsenides (cobaltite and its analogs), as well as mine rals of Ag (hessite) and Pb (kuranakhite and phases similar in composition to minerals of the dugganite group and burckhardtite). Conclusions. The sustained composition of native gold and a narrow range of salinity and homogenization temperatures of fluid inclusions indicate the formation of gold during a single stage of mineralization. The main source of gold could have been the dolerite dikes of the Ulugurtau complex. The presence of CO2, N2 and CH4 gases in fluid inclusions from goldbearing quartz indicates that not only magmatic fluid, but also fluid from the host rocks took part in mineral formation. The low value of the ratio X(CO2)/X(CH4) ≤ 0.7 indicates a moderately reduced ore-forming fluid. Low Au concentrations (0.1– 0.4 ppm) in quartz veins, dolerites, and gabbro-diorites, including those containing visible gold, indicate a weak commercial potential of the deposit

Geological and geochemical characteristics of the Wulong gold deposit, Liaodong Peninsula: Implications for gold mineralization

As a typical hydrothermal vein-type gold deposit in the eastern Liaodong Peninsula, northeast of North China Craton, the Wulong gold deposit is associated with the Jurassic gneissic two-mica granites with gold reserves over 80 t. In this paper, the gold precipitation and enrichment mechanism of the Wulong deposit is investigated by studying the morphological structure and geochemical characteristics of pyrite. Pyrites are divided into four types based on their microstructural characteristics: Py1 is represented by disseminated pyrite, which was developed in granites; Py2a is dominated by porous pyrite, which developed in the early quartz-pyrite vein; Py2b commonly wraps Py2a, distinguished from Py2a by its “smooth” surface, and developed in the quartz-polymetallic sulfide stage; Py3 was observed in quartz-calcite-fluorite stage. X-Ray Fluorescence Spectrometer (XRF) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS) analysis revealed the enrichment of trace elements in pyrite at different stages: 1) In an overall view, the strong positive correlation among chalcophile elements was detected; 2) The total amount of trace elements in Py1 and Py3 was significantly lower than that in Py2a and Py2b; 3) In Py2a, the content of chalcophile elements represented by Ag, Te, Bi and Pb is higher than that of other types of pyrite, and gold mainly coexists with those elements in the form of nanoscale micro-inclusions (Au0); 4) The lattice gold (Au+) was positively correlated with As in Py2b. In contrast to the extremely low invisible gold content (Py1: 0.94 ppm; Py2a: 2.23 ppm; Py2b: 4.45 ppm; Py3: 0.28 ppm) in pyrite, there is a large amount of visible gold in the deposit in the form of scattered natural gold and electrum particles (silver content 4.38–36.01%). In addition, these visible gold is often associated with mineral aggregates consisting of galena, native bismuth, joséite-B, etc. Combined with the research results of previous studies, we proposed that visible gold is the main source of gold in the Wulong gold deposit. It is concluded that the occurrence of a large amount of visible gold in this deposit is closely related to the thinning and destruction event of the North China Craton during the Mesozoic. Different from the deposition characteristic of gold in gold-rich pyrite, in the high arsenic (>2000 ppm) area of pyrite, only very low gold content less than 5 ppm was detected. Meanwhile, the complex dyke intrusion and cutting phenomena observed in the mining area indicate the multi-stage tectonic activities in the metallogenic stage. Therefore, a reasonable explanation is that the pressure of the ore-forming fluid decreased sharply during tectonic activity, which promoted the separation of fluid phases and resulted in the massive precipitation of natural gold and chalcophile elements. This paper is of great significance to the gold prospecting in the Liaodong Peninsula, and also provides an important reference for the comparative study of metallogenic mechanisms in the Liaodong Peninsula and Jiaodong Peninsula.

Carrier mobility in field effect transistors based on copper-phthalocyanine thin films with different phase structure

Using annealing procedure at different temperatures after deposition at room temperature we obtained copper- phthalocyanine (CuPc) thin films with a — and p —phase structure. A phase structure of thin films was controlled by X-ray diffraction method, morphology was controlled by SEM. The field effect transistors was fabricated by high vacuum deposition of CuPc thin film (thickhess of 100 nm) on Si02 substrate which acting as gate contact. Gold drain and source contacts deposited on the top of active layer of FET. From measured current voltage measurements calculated mobility and concentration of charge carriers in FET. These parameters depend on phase structure of CuPc thin film, and characteristics of our FET are comparable with values of other authors.
 CuPc is commercially available macro cyclic metal complex that can be easily obtained in large quantity and high purity. Together with other phthalocyanine derivatives, the chemically and thermally stable CuPc has wide applications in dye processing, spectral sensitization, chemical sensors, and optical data storage [3-4]. The semiconducting behavior of metal phthalocyanines was first observed in 1948 and they have since attracted great interest in advancement of protptype organic semiconductors. Among the metal substituted phthalocyanines CuPc has been found superior properties [5-7], such as phenomena of field dependent and wavelength-dependent efficiency in an organic static induction transistors, and stabilizing role of CuPc layer on a highly stable organic electroluminescent device based on thin film Alq, and indicated a very weak interaction between CuPc and Au at the interface.
 In general, phthalocyanine materials can exist in several crystalline polymorphs, including a-, p -, x-and y - structure, and the most well known are the thermally metastable a- and p - [8-10], Phthalocyanine films deposited at room temperature usually consist of a-phase crystallites (at sublimation pressure of less than 10 Pa). At higher deposition pressures or at substrate temperature above 210°C, the p -phase directly obtained [11], Although it is well known that a-phase crystallites undergo a phase transformation into P -phase by treatment in various organic suspension media [12,13] or during annealing at higher temperatures [14,15], only some authors describe the nature of the a—>p phase transformation of copper phthalocyanine thin films with a thickness of less than 100 nm [8,14-15].

Evaluation of economic efficiency of mining technogenic deposits of placer gold with the formation of concentration zones

Currently, mineral reserves of gold placers are depleted largely due to a significant reduction of geological exploration. In view of the drop in gold production from placers, an important source of gold in many areas of the Far East Federal District becomes waste and natural-and-manmade placer deposits. By experts’ estimates, the resource potential of manmade placer deposits (waste) is very high. Billions of cubic meters of gold-bearing waste is accumulated in dumps. These are, first of all, dredge and sluice tailings dumps. The average gold content of such material mainly agrees with the modern economic standards. Sometimes, it is even comparable with the gold content of natural deposits. Obviously, effective development of manmade placer deposits is possible using new technologies, at selected and optimized design and process variables of mining and processing equipment subject to the whole set of influences. Creation of such technologies is an urgent scientific and technical task within the concept of efficient natural and manmade mineral resources management. The Institute of Mining, FB RAS formulates and accomplishes the research on development and theoretical justification of a geotechnology for manmade mineral deposits on the basis of concentration of valuable components inside waste dumps, which ensures formation of a pay zone nearby the bedrock. This study aims at the economic evaluation of the effectiveness of new organizational and engineering solutions to improve the level and completeness of gold recovery from manmade deposits.The studies were carried out using the resources of the Center for Shared Use of Scientific Equipment “Center for Processing and Storage of Scientific Data of the Far Eastern Branch of the Russian Academy of Sciences”, funded by the Russian Federation represented by the Ministry of Science and Higher Education of the Russian Federation under project No. 075-15-2021-663.

Study on AuNPs size regulation and AuNPs/BP photocatalytic performance

As a new two-dimensional material, black phosphorus (BP) has many advantages, like layer-dependent direct band gap, wide spectral response, high carrier mobility and abundant active sites. It is widely used in photocatalysis, solar energy conversion and other fields. However, the rapid recombination of photo-generated carriers and poor chemical stability limit the development of BP in the field of photocatalysis. In this study, a composite photocatalyst was configurated by loading Au nanoparticles (AuNPs) on the surface of the BP, namely AuNPs/BP. By adjusting the conditions such as reducing agent, protective agent, temperature, gold source in the reaction system, the mechanism and influencing factors of AuNPs particle size were explored. The composite catalyst was characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet–visible spectrometry (UV–vis), X-ray photoelectron energy spectrometry (XPS), and photochemical test platforms. Next, the catalytic performance of AuNPs/BP was evaluated by photocatalytic degradation of methyl orange (MO). The results showed that the degradation performance of AuNPs/BP on MO is significantly better than that of pure BP, and the degradation rate increased from 49.7% to 67.7%. The apparent rate constant increased from 5.726 × 10−3min−1 to 9.418 × 10−3min−1. Due to the surface proton resonance effect of AuNPs, BP with AuNPs evenly loaded on the surface showed strong absorption of visible light, high carrier separation efficiency, and widened the band gap of BP.

Ore fluid origin recorded by apatite chemistry: A case study on altered dolerite from the Badu Carlin-type gold deposit, Youjiang basin, SW China

The Paleozoic-Mesozoic Youjiang sedimentary basin in SW China is developed on a Lower Paleozoic low-grade metamorphic basement, and contains dozens of Carlin-type gold deposits with a total Au reserve of over 900 metric tonnes (t). Although most of these deposits are hosted in sedimentary rocks, ∼70% of the gold (∼24.5 t) in the Badu deposit is hosted in altered OIB-type dolerite. To date, the ore-fluid source of Carlin-type gold deposits in the basin is highly debated, hampering the formulation of genetic models. Here, for the first time, we present ore-related apatite chemical and Sr isotope compositions from the altered dolerite at Badu to provide new insight into the ore-fluid source of this key gold province.Petrography studies distinguished three apatite generations (Ap1 to Ap3): Pre-ore Ap1 is needle-shaped or fine-grained (<20 μm), and occurs mainly in the unmineralized dolerite; Main-ore Ap2 is euhedral-subhedral coarse-grained (>100 μm) and spatially associated with auriferous pyrite and arsenopyrite in the mineralized dolerite; Late-ore Ap3 is also euhedral-subhedral coarse-grained (>100 μm), and hosted in quartz ± ankerite veins crosscutting the mineralized dolerite. Geochemically, Ap1 contains relatively high Cl (∼0.134 wt%), MnO (∼0.038 wt%), MgO (∼0.155 wt%), and SiO2 (∼0.285 wt%) contents, whereas Ap2 and Ap3 have relatively high SrO contents (∼0.448 and ∼0.45 wt%, respectively). This geochemical difference can be used to distinguish magmatic from hydrothermal apatite at Badu. Ap2 has similar chemistry to Ap3 except for the higher SO3 contents (up to ∼0.318 wt%), and they both have similarly higher 87Sr/86Sr ratios (0.709489–0.711787) than those of the unmineralized dolerite (0.706295–0.706323) and the sedimentary ore host in the basin, but similar to the Lower Cambrian basement rocks (0.70909–0.82733). This similarity indicates that the ore-forming fluids were dominantly sourced from the basinal basement or from deep magmatic fluids with radiogenic Sr addition from the basement rocks. The ore-forming fluids may also have leached MREEs from the sulfate-rich basement rocks, leading to the observed MREE enrichments in Ap2 and Ap3. Our study highlights that the basement material contribution is critical for the Carlin-type gold mineralization in the Youjiang basin.

Nanoparticles Impression on Creatine Kinase Activity

Nanoparticles (NPs) are purchased from Sigma-Aldrich (730785). Sodium citrate as stabilizer comprises 10 nm particle size (TEM), dispersion (NPs), stabilizer Silver, and 0.02 mg/mL in aqueous buffer relative molecular mass (107.87). The concentration number (3.6×1012) packaging 25mL in a glass bottle. 10 nm diameter golden nanoparticles OD 1, stable 0.1 mM suspension is an aqueous salt solution that contains common salt, dihydrogen phosphate, and dilute phosphate-buffered saline (PBS). It also contains potassium dihydrogen phosphate and potassium chloride in certain formulations. While the pH rises, the role of the buffer is to regulate it. NPs, equipped with (Sigma-Aldrich752584) relative molecular mass (196.97). Structural and optical nanoparticles are studied. Findings show a nanoparticle size of approximately 10 nanometers. The silver and gold sources’ impact on healthy people’s creatine kinase (CK) activity within the blood was in vitro-studied. The results indicated that the nanoparticles of silver and gold had a dissimilar impact on serum CK activity. The gold particles tonic impacts serum CK activity and increases the activity of enzymes as the concentration of nanoparticles increases because it acts as an enzyme activator. At the same time, silver nanoscale has an inhibitory effect thereon.

Selective recovery of gold from e-waste with 3D hierarchical porous amidoximated fabrics and its application in the reduction of 4-nitrophenol

Recycling gold from waste provides an alternative path to meet the increasing global gold consumption, and gold catalysts account for a considerable portion of this recycling effort. In this study, amidoximated fabrics (AO-NWF) were fabricated with pre-irradiation graft polymerization method. Afterwards, we used an Intel Pentium CPU as a gold source and employed an integrated strategy for the in-situ fabrication and stabilization of gold nanoparticles (AuNPs) on 3D hierarchical porous amidoxime fabrics (Au@AO-NWF) to catalyze the reduction of 4-nitrophenol in water. Au@AO-NWF showed remarkable and stable catalytic performance, recording a maximum reaction rate constant of 0.5994 min−1. Finally, the recovered gold could be further used in electronic equipment. Thus, a green, closed-loop utilization of gold was accomplished, which could help reduce electronic waste (e-waste) pollution, superfluous sources, and energy consumption to protect the environment. As a candidate for gold adsorption, the ability of AO-NWF to extract gold from water was also evaluated in detail.