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EISSN : 2075-163X
Published by: MDPI (10.3390)
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Published: 24 June 2022
by MDPI
Abstract:
The borehole transient electromagnetic (TEM) method can be useful in deep mineral exploration to detect blind ore bodies beside or below the borehole, and is especially adapted to finding small-scale, deep, rich ore bodies. In this method a transmitting loop is deployed on the top surface of the Earth, while a receiving coil is moved down the borehole. As the borehole TEM method is limited by the borehole’s location and depth, so its exploration scope is limited. The surface to airborne TEM method is a semi-airborne TEM configuration that transmits on the surface and receives TEM response in air. The two systems are combined into one system in this study, sharing the transmission loop deployed on the surface. With this combined system, the TEM response in the borehole and in the air can be observed at the same time. This paper employs a joint interpretation method based on the equivalent filament, which is introduced to obtain more reliable geometric information for the target with both borehole and aerial TEM data. The eddy currents induced in a thin confined conductor can be represented by equivalent current filaments, and the distribution of filaments can reflect the position and geometry of the conductor. Therefore, geometric parameters of targets can be obtained by filament inversion, and the joint inversion can be more accurate with both borehole and aerial response. Numerical modeling results show that the joint inversion based on the equivalent filament results can reliably obtain the geometric parameters of the thin conductive plate embedded in half space.
Published: 24 June 2022
by MDPI
Abstract:
Grinding is an important link in the process of mineral processing. It plays a vital role in mineral processing by optimizing the grinding process, improving the quality of grinding products and ensuring the follow-up operation indicators. In this paper, the Python language, intelligent theoretical control technology and mineral processing were combined to solve the problem of ore feeding control in mineral processing. Using error factor analysis, an extended control algorithm was designed. The NumPy library and data collected from the Yuan YangMou concentrator in China were used to quantitatively analyze the factors affecting the error of electronic belt scales. This paper introduces the use of Kalman filtering for electronic belt scale weight data to reduce the effect of noise and hence reduce errors. The factors affecting the process of mill feeding are also analyzed. The core ideas and methods of fuzzy control theory are summarized, and a Python-based fuzzy controller suitable for the mill feeding process that improves the overall robustness and accuracy of feeding system is implemented.
Published: 24 June 2022
by MDPI
Abstract:
The Yunnan–Guizhou–Guangxi district (also known as the Dian–Qian–Gui “Golden Triangle”) in southwestern China contains numerous Carlin-type Au deposits (CTGDs). However, the sources of Au and Au-bearing fluids in these deposits remain controversial. The Tangshang Au deposit is a middle-sized CTGD in southeastern Yunnan Province. This study involved in situ chemical and S isotope analyses of sulfides and in situ trace elemental and Sr isotope analyses of ore-related calcite; these data were used to trace the sources of fluids and Au, as well as the genesis of this deposit. Four pyrite types (Py1, Py2, Py3, and Py4) and two arsenopyrite types (Apy1 and Apy2) were identified based on their textural characteristics. It was found that Py1 contains relatively lower Au, Sb, Cu, and Tl contents than those of Py2, Py3, and Py4. Py1 is wrapped by rim-Py2 and Py3, which indicates an early-ore-stage genesis. The Carlin-type mineralization elements are elevated in the pyrites (Au = 3.04–38.1 ppm; As = 40,932–65,833 ppm; Tl = 0 to 3.3 ppm; Sb = 1.2 to 343 ppm; and Cu = 10 to 102 ppm), and the average Co/Ni ratio is 0.54. Additionally, Au has a positive correlation with Tl and Cu. The high concentrations of As and Au in all types of pyrite indicate that the ore-forming fluids are rich in both elements. The sulfides in the ores were shown to produce similar S isotope ratios, which are obviously higher than the S isotope value of sulfide (~0‰) in Emeishan basalt; therefore, the integration of these and elemental composition data indicated that all pyrites (Py1, Py2, Py3, and Py4) form during the ore stage. These results also demonstrate that the δ34S values of the Au-bearing fluids are higher than those of basalt wall rocks. The flat chondrite-normalized REEs pattern and positive Eu anomaly of the calcite were similar to those obtained from Emeishan basalt, which suggests a reducing characteristic of hydrothermal fluids. The 87Sr/86Sr ratios (0.70557–0.70622) of calcite were also comparable to the range obtained from Emeishan basalt. Some slightly higher 87Sr/86Sr ratios, which ranged between those obtained from Emeishan basalt and limestone from the Maokou Formation, indicated that the Sr isotope ratios of the Au-bearing fluids are higher than those of Emeishan basalt. Based on data generated in the present study and the regional geology of this area, a genetic model involving a metamorphic fluid system was proposed for the Tangshang gold deposit, and a gold mineralization event related to metamorphic fluid in the south of the Dian–Qian–Gui “Golden Triangle” was indicated.
Published: 24 June 2022
by MDPI
Abstract:
The crushing chamber is the core component of a cone crusher, consisting of mantle and concave parts. Reducing the impact of crushing chamber wear on the performance of cone crushers and the quality of crushed products while extending the service life of the mantle and concave has become a significant research challenge. The impact of the compression ratio and particle size distribution coefficient on the particle crushing pressure is investigated here in order to establish the particle pressure model. The effect of the normal and tangential components of particle crushing pressure on the wear of the mantle and concave is discussed, and the wear with the increase in crushed products and accumulation of operating time is explored in order to develop a wear model of the crushing chamber. By evaluating the compensation of the worn crushing chamber according to the adjustment mechanism of the mantle, a constant wear criterion for the crushing chamber of the cone crusher is proposed. Through analysis of industrial experimental data on an experimental prototype of a ZS200MF cone crusher with an optimized mantle and concave, the capacity was found to fluctuate at 83.45 t/h with no apparent downward trend, the calibration size production was reduced by 6.2%, and the wear similarity coefficient was 8.82%. This indicates that replacing the optimized mantle and concave based on the constant wear criterion maintains the performance of the cone crusher, delays the decline in the quality of the crushed products, and ensures similarity between the adjusted worn crushing chamber and the initial crushing chamber, which verifies the feasibility and effectiveness of the constant wear criterion for the optimization of crushing chamber. Based on the constant wear criterion, cone crushers can be optimized to obtain a crushing chamber with constant wear characteristics, which provides theoretical support for the development of new high-efficiency cone crushers as well as the optimization of existing equipment.
Published: 24 June 2022
by MDPI
Abstract:
Nine samples collected from the Upper Cretaceous Second White Speckled Shale Formation at the Highwood River outcrop in southern Alberta were geochemically characterized for their oil contents, physical states, and chemical compositions. Cold extraction was performed on 8–10 mm and 2–5 mm chips sequentially to obtain the first and second extractable organic matter (EOM-1 and EOM-2), while Soxhlet extraction was performed on powder from previously extracted chips to obtain the third extract (EOM-3). EOM-1 can be roughly regarded as free oil and EOM-2 is weakly adsorbed on mineral surfaces, while EOM-3 may represent the oil strongly adsorbed on kerogen. While both extraction yields and Rock-Eval pyrolysates differed from their original values due to the evaporative loss during outcropping, there was a generally positive correlation between the total EOM and total oil derived from Rock-Eval pyrolysis. EOM-1 was linearly correlated with Rock-Eval S1, while the extractable S2 content was well correlated with the loss of TOC, suggesting that TOC content was the main constraint for adsorbed oils. A bulk composition analysis illustrated that EOM-1 contained more saturated hydrocarbons, while EOM-3 was enriched in resins and asphaltenes. More detailed fractionation between the free and adsorbed oils was demonstrated by molecular compositions of each extract using quantitative GC-MS analysis. Lower-molecular-weight n-alkanes and smaller-ring-number aromatic compounds were preferentially concentrated in EOM-1 as compared to their higher-molecular or greater-ring-number counterparts and vice versa for EOM-3. Fractionation between isoprenoids and adjacent eluted n-alkanes, isomers of steranes, hopanes, alkylnaphthalenes, alkylphenanthrenes and alkyldibenzothiophenes was insignificant, suggesting no allogenic charge from deep strata. Strong chemical fractionation between saturated and aromatic hydrocarbon fractions was observed with EOM-1 apparently enriched in n-alkanes, while EOM-3 retained more aromatic hydrocarbons. However, the difference between free and adsorbed state oils was less dramatic than the variation from shales and siltstones. Lithological heterogeneities controlled both the amount and composition of retained fluids. Oil that resided in shales (source rock) behaved more similar to the EOM-3, with diffusive expulsion leading to the release of discrete molecules from a more adsorbed or occluded phase to a more free phase in siltstones with more connected pores and/or fractures (reservoir). Under current technical conditions, only the free oil can flow and will be the recoverable resource. Therefore, the highest potential can be expected from intervals adjacent to organic-rich beds. The compositional variations due to expulsion and primary migration from source rocks to reservoirs illustrated in the present study will contribute to a better understanding of the distribution of hydrocarbons generated and stored within the shale plays.
Published: 24 June 2022
by MDPI
Abstract:
Since the Quaternary, the alternate climate of dry and wet, cold and warm, and the emergence of glacial and interglacial periods have led to great changes in the global environment and climate. As an event closely related to cold climate, cryogenic soil has important reference significance for the study of climate change in a certain region and time period. The research on cryogenic soils mainly focuses on the following three aspects: particle size composition, surface morphology and mineral composition. Through the study of the relevant literature, we find that the correlation coefficient of particle size composition before and after freeze-thaw is used to determine the cause of cryogenic weathering. Due to the singleness of judgment conditions, the result is difficult to be convincing; It is difficult to prove the microscopic morphology of the cause of cryogenic weathering from a single mineral of quartz. Therefore, it is necessary to start with more types of primary minerals, and analyze the differences in the particle shape and microscopic surface morphology of different types of primary minerals during the cryogenic weathering process. And on this basis, the typical mineral morphology of the cause of cryogenic weathering is comprehensively judged; Freeze-thaw has little effect on the mineral composition of the soil, but has a greater impact on the size of the mineral particles, and this size change corresponds to the phenomenon of particles silt-fication. The mineral composition also controls the geochemical composition, and the insignificance of the mineral-chemical composition in the process of cryogenic silt-fication increases the difficulty of judging the cause of cryogenic weathering.
Published: 24 June 2022
by MDPI
Abstract:
The chemical reaction between calcium ions (Ca2+) and phosphate in the soil is the main way to maintain the availability of soil phosphorus. Thus, we believe stimulating coal gangue with Ca2+ solution would be an effective way to improve its adsorption and desorption capacity toward phosphate. In order to explore the effects of different pH of Ca2+ solution on the modified effect of coal gangue, we conducted mechanical grinding (<1 mm), high temperature calcination (800 °C), and the stimulation of Ca2+ solution with different pH (2, 7, 13), to prepare acidic calcium-modified coal gangue (Ac-CG) (Ac-CG, acidic calcium-modified coal gangue; Ne-CG, neutral calcium-modified coal gangue; Al-CG, alkali calcium-modified coal gangue; RCG, raw coal gangue), neutral calcium-modified coal gangue (Ne-CG), and alkali calcium-modified coal gangue (Al-CG); raw coal gangue (RCG) was regarded as the control. The results indicated that Al-CG had better phosphate adsorption (3.599 mg g−1); this favorable adsorption performance of Al-CG was related to the formation of hydrated calcium silicate gel and ettringite, which provided more Ca2+, Al3+, and hydroxyl groups, and a larger specific surface area (9.497 m2 g−1). Moreover, Al-CG not only held more phosphate but also maintained its availability longer for plants. It is suggested that stimulating coal gangue with Ca2+ solution under alkaline conditions is a perfect way to enhance its adsorption and desorption capacity toward phosphate; the Al-CG we prepared could be used as filling material and soil conditioner in the reclamation area.
Published: 23 June 2022
by MDPI
Abstract:
The Changkeng–Fuwan Au-Ag deposit is representative in South China, which is located in the southwest of the Qin–Hang metallogenic belt (QHMB). The Au and Ag orebodies are located in the same altered fracture zone, forming independent gold and silver orebodies respectively, with the characteristics of “upper gold and lower silver” in space. Three metallogenic stages have been identified: the pyrite–quartz–sericite stage, the polymetallic sulfide stage, and the quartz–calcite stage. The fluid inclusions (FIs) from the deposit are the two-phase liquid-rich (type I) and the pure liquid FIs (type II). The microthermometric measurements of type I FIs are characterized by temperatures of 158–282 °C and 146–289 °C and salinities of 0.35–9.88 wt.% NaCl equiv. and 0.18–11.70 wt.% NaCl equiv. The H, O, He, and Ar isotopic data show that the ore-forming fluids of the deposit were derived from a mixture of magmatic and meteoric fluids. The C and O isotopic data suggest that the carbon of the fluid may derive from a magmatic source. The S and Pb isotopic data indicate that the primary source of the metals in the Changkeng–Fuwan deposit may be a magma source. Based on the geological characteristics, FI microthermometry, and isotope data (C, H, O, He, Ar, S, and Pb), we propose that the Changkeng–Fuwan deposit should be classified as a far-source low-temperature magmatic–hydrothermal deposit.
Published: 23 June 2022
by MDPI
Abstract:
The Black Angel Zn-Pb ore deposit is hosted in folded Paleoproterozoic marbles of the Mârmorilik Formation. It is exposed in the southern part of the steep and inaccessible alpine terrain of the Rinkian Orogen, in central West Greenland. Drill-core data integrated with 3D-photogeology and hyperspectral imagery of the rock face allow us to identify stratigraphic units and extract structural information that contains the geological setting of this important deposit. The integrated stratigraphy distinguishes chemical/mineralogical contrast within lithologies dominated by minerals that are difficult to distinguish with the naked eye, with a similar color of dolomitic and scapolite-rich marbles and calcitic, graphite-rich marbles. These results strengthen our understanding of the deformation style in the marbles and allow a subdivision between evaporite-carbonate platform facies and carbonate slope facies. Ore formation appears to have been mainly controlled by stratigraphy, with mineralizing fluids accumulating within permeable carbonate platform facies underneath carbonate slope facies and shales as cap rock. Later, folding and shearing were responsible for the remobilization and improvement of ore grades along the axial planes of shear folds. The contact between dolomitic scapolite-rich and calcitic graphite-rich marbles probably represents a direct stratigraphic marker, recognizable in the drill-cores, to be addressed for further 3D-modeling and exploration in this area.
Published: 22 June 2022
by MDPI
Abstract:
In this paper, the depositional environment, age, and tectonic context of the Sub-Himalayan Kuldana Formation are discussed in detail. To determine the Kuldana Formation’s depositional environment, age, and tectonic setting, sedimentological, palaeontological, and petrographic investigations have been conducted accordingly. The Kuldana Formation lithologically consists of both siliciclastic and carbonate rocks. Petrographically, the Kuldana Formation’s sandstone is divided into litharenite and feldspathic litharenite petrofacies. The sandstone plots on the QtFL and QmFLt suggest that the sandstone of the Kuldana Formation derived from a recycled orogen provenance field that developed during the collision of the Indian and Eurasian plates in the Lesser and Higher Himalayas. The plots in the diamond diagram further demonstrate that the detritus of the Kuldana Formation was derived from low and middle-to-upper rank metamorphic rocks of the Himalayas. Throughout the deposition of sandstone, paleo-climate conditions were semi-humid to semiarid. Dolostone and limestone are the two main types of carbonate rocks found in the Kuldana Formation. According to Dunham’s Classification, the Kuldana Formation limestone is classified as mudstone, wackstone, and packstone. These petrofacies suggest that the limestone was deposited in an inner-outer ramp setting. The bioclasts include bivalves, brachiopods, crinoid, gastropods,Globigerinoides spp, Lockhartia pustulosa, miliolids, Nummulites atacicus, Nummulites discorbina, Nummulites mamillatus, Nummulites djodjokartae, Nummulites vascus, and ostracods suggesting that the age of Kuldana Formation is Middle Eocene- early Oligocene. The Kuldana Formation was deposited during the initial stages of the Himalayan Orogeny as a result of the Ceno-Tethys Ocean’s regression and transgression, as revealed by a succession of siliciclastic and non-clastic rocks.
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