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The mining strata in the western mining area of China are mainly composed of Jurassic and Cretaceous strata. The strata are characterized by low strength, poor cementation and easy disintegration, which belong to weakly cemented rocks. The surrounding rock of the weakly cemented stratum project is quite different from the stratum rock of the central and eastern mining areas. It is difficult to effectively guarantee the safety of the project by using traditional control technologies such as roof control of the working face and surrounding rock control of the roadway. Disasters such as large deformation and instability of the roadway, crushing of the working face, water inrush, sand inrush, rock burst and so on. Through a large number of investigations and laboratory experiments, the mechanical indexes such as tensile and compressive strength of weakly cemented rocks are much smaller than those of similar rocks in the central and eastern mining areas. The evaluation index system of the variation degree of weakly cemented rocks under the coupling of multiple factors is established, and the variation degree of weakly cemented rocks in typical mining areas is preliminarily obtained. Taking the weakly cemented rock in Hongqinghe Coal Mine as an example, it is found that the weakly cemented rock has the phenomenon of ‘phase transition’ under the action of force, water and other loads. The influence of cementation degree on the phase transition phenomenon is analyzed, and the ‘phase transition’ state characteristics and sensitivity parameters of weakly cemented coarse-grained sandstone are given. The dynamic development law of overburden caving zone and fracture zone and the large deformation law of roadway surrounding rock are studied and analyzed, which lead to the support crushing, water inrush and sand inrush disasters in the working face. The dynamic change expression of caving zone in different mining stages of large mining height working face in weakly cemented strata is deduced, and the support-surrounding rock interaction model is established. The working resistance of support during weighting and non-weighting of working face is given. Aiming at the loose and weak characteristics of weakly cemented strata, the double shell reinforcement technology of roadway surrounding rock is proposed, which can provide guarantee for safe mining of working face and control of roadway surrounding rock.

The shaft is a key project, including the mining of shaft engineering minerals and the development and utilization of underground space. As the lower part of the proposed shaft has the advantage of a production system, the use of gravity slag removal is one of the important directions for the development of large-diameter shaft drilling technology. Aiming at the problems such as discontinuous slag discharge, low efficiency, and difficult to cooperate with the rock breaking process, the bucket type slag discharge technology exists. It is necessary to explore how to change the slag discharge mode of the working face during shaft sinking. The gravity slag removal process can improve the efficiency of shaft sinking, that is, through the pre establishment of a small diameter pilot shaft connecting the upper and lower levels of the proposed shaft, or when the upper horizontal construction conditions are not available, the pilot shaft can be directly drilled upward horizontally under the shaft. Under the action of gravity, the crushed rock slag will fall directly to the lower level and then be transported and discharged by loading equipment. Firstly, the applicability and limitation of the slag removal technology with positive and reverse fluid circulation in mechanical rock breaking drilling are discussed. Based on the weight of rock slag, the process of gravity slag removal is proposed. The development status of mechanical rock breaking and gravity slag removal technologies such as large-diameter shaft raise drilling, direct upward raise drilling and pilot shaft boringare analyzed.The problems faced by mechanical rock breaking drilling technology based on gravity slag removal at this stage, such as efficient crushing, stable and reliable drilling tools, controllable drilling deflection, and intelligent drilling, are summarized. The technical processes and equipment of pilot hole drilling, pilot shaft drilling, drilling and blasting expansion, raise shaft drilling expansion, raise shaft drill expansion and shaft boring machine expansion are systematically sorted out. A comprehensive well completion process system with different process combinations has been established. Mechanical rock breaking shaft sinking technology based on gravity slagging will continue to play an important role in the construction of large-diameter shafts in coal mines, metal mines, hydropower, transportation and other fields, and provide reference and reference for the technical development of unmanned, mechanized and intelligent shaft construction.

The Xiong'ershan district is situated on the southern margin of the North China Craton (NCC) and located within the Qinling–Dabieshan Orogen's orogenic zone. It is adjacent to the XiaoQinling mining district and exhibits very favorable geological conditions for mineralization, as the district contains numerous gold deposits, positioning it as one of the key gold-producing areas of China. The Miaoling gold deposit is a hydrothermal deposit and is controlled by the Mesozoic nearly NS-trending fault. The ore bodies are hosted in the Mesoproterozoic Xiong'er Group of the Changcheng System of volcanic rocks, with reserves reaching large-scale levels. Pyrite is the main gold-bearing mineral and can be classified into four generations: early-stage fine- to medium-grained euhedral to subhedral cubic pyrite (Py1); medium- to coarse-grained euhedral to subhedral cubic granular pyrite in quartz veins (Py2a); fine-grained subhedral to anhedral disseminated pyrite in altered rocks (Py2b); and late-stage anhedral granular and fine-veinlet pyrite in later quartz veins (Py3). Through in situ trace element analysis of the pyrite using LA-ICP-MS, a positive correlation between Au and As was observed during the main mineralization stage; gold mainly exists as a solid solution within the pyrite lattice, and the ablation signal curve reflecting the intensity of trace element signals showed that gold also occurs as micron-scale mineral inclusions. The trace element content suggested a gradual increase in oxygen fugacity from Stage 1 to Stage 2, followed by a decrease from Stage 2 to Stage 3. The Co/Ni values in the pyrite (0.56 to 62.02, with an average of 12.34) exhibited characteristics of magmatic hydrothermal pyrite. The in situ sulfur isotope analysis of the pyrite using LA-MC-ICP-MS showed δ34S values of 4.24‰ for Stage 1, −6.63‰ to −13.79‰ for Stage 2, and −4.31‰ to −5.15‰ for Stage 3. Considering sulfur isotope fractionation, the δ34S value of the hydrothermal fluid during the main mineralization stage was calculated to be between 0.31‰ and 2.68‰. [ABSTRACT FROM AUTHOR]

To enhance the electrochemical stability and kinetics of V2O5, 3,4-ethylenedioxythiophene (EDOT) was in situ polymerized within V2O5 interlayers, rendering PEDOT@V2O5 with enlarged layer spacing, increased stability in organic electrolyte, and superior electrochemical kinetics (bleaching/coloration times 10.9/9.1 s) and cyclability (98.5% ΔT and 85.6% capacity retention after 1000 cycles) in a PEDOT@V2O5‖Zn electrochromic device. [ABSTRACT FROM AUTHOR]

The Antarctic Circumpolar Current (ACC) is Earth's largest current flowing around Antarctica at all depths and connecting major ocean basins, thus representing an important component of Earth's climate. However, the timing and key controls determining ACC flow path and its strength as a function of past climatic boundary conditions that ultimately resulted in its modern configuration remain unclear due to major uncertainties in paleoceanographic and tectonic reconstructions. Here we present a unique high‐resolution laser ablation‐derived late Cenozoic seawater lead isotope record obtained from a hydrogenetic ferromanganese crust from the Pacific sector of the Southern Ocean. Our Pb isotope data reveal that the ACC has experienced five stable circulation states since the early Miocene which were separated by four major transitions observed at 17.5‐14.6, 12, 10 and 5 Ma. We suggest that the relatively abrupt transitions between ACC circulation state were mainly induced by tectonic changes, whereas the impact of climatic changes was of secondary importance. According to our data the modern ACC configuration formed 5 million years ago, likely in response to the closure of the Panama Seaway. Since the Drake Passage (DP) has already been an open seaway since at least the late Miocene, our results demonstrate that DP opening was not the only factor affecting past ACC circulation. Our data also show that changes in the latitudinal position of the ACC were linked to the middle Miocene waxing and waning of the Antarctic ice sheets, which emphasizes the ACC's critical role as a key control of Antarctic glaciation. Key Points: Five stable circulation states of Antarctic Circumpolar Current (ACC) in the Pacific sector are identified by seawater Pb isotopes since the early MioceneACC dynamics linked to the middle Miocene waxing and waning of the Antarctic ice sheetThe ACC in its modern configuration formed about 5 million years ago following the final closure of the Panama Seaway [ABSTRACT FROM AUTHOR]