Advances in mining safety theory, technology, and equipment

Mineral resources are an important pillar of human social development. With the gradual depletion of shallow resources, deep mining is an inevitable choice for ensuring energy security in various countries in the future. The complex and harsh environment in deep mining areas has led to frequent occurrences of hazardous events such as rockburst, coal and gas outburst, and mine fires. Mining safety science and engineering issues are receiving increasing attention. In August 2023, the 6th International Symposium on Mine Safety Science and Engineering was held in Harbin to promote innovative development of mining safety, and foster international collaborations among scholars in the field of mining safety. It served as a platform for the exchange of the most recent advancements in mining safety scientific theories, technologies, and equipment by bringing together global talent. Over 400 delegates representing 9 countries, including Australia, Russia, United State, Kazakhstan, and Canada, engaged in academic discussions and knowledge sharing on new theories, technologies, equipment, and methods in mining safety science and engineering. The latest research results are of great significance in enhancing the practices of preventing mine disaster and ensuring the safety of mining operations.Document Type: EditorialCited as: He, S., He, X., Mitri, H., Meng, S., Wu, Q., Ren, T., Liu, S. Advances in mining safety theory, technology, and equipment. Advances in Geo-Energy Research, 2023, 10(2): 71-76. https://doi.org/10.46690/ager.2023.11.0

The method of coal and gas outburst risk zones division based on quantitative coupling of gas and stress

In order to realize the accurate division of coal and gas outburst risk zones, taking Juji Coal Mine as the case study, the method of coal and gas outburst risk zones division based on quantitative coupling of gas and stress is proposed. The results show that the high gas pressure zones are concentrated in the eastern of No.23 mining area, and most of No.26 and No.27 mining area. The vertical stress in the mine ranges from 6 MPa to 36 MPa. The comprehensive weights of gas pressure and stress are determined by AHP-entropy weight method, and the outburst risk comprehensive index Q is calculated accordingly. According to the range of Q, the mine is divided into low risk zone (Q \u3c 0.5), medium risk zone (0.5 ≤ Q ≤ 0.75) and high risk zone (Q \u3e 0.75). It has been verified that the drilling cuttings S value in No.26 mining area (high risk zone), No.27 mining area (medium risk zone) and No.211 mining area (low risk zone) is 3.6~4.8 kg/m, 3.2~4.6 kg/m and 3.0~4.4 kg/m, and the initial gas emission velocity q value ranged from 0 to 3.7 L/min, 0 to 0.46 L/min and 0 L/min, respectively

Stroke genetics informs drug discovery and risk prediction across ancestries

Previous genome-wide association studies (GWASs) of stroke — the second leading cause of death worldwide — were conducted predominantly in populations of European ancestry1,2. Here, in cross-ancestry GWAS meta-analyses of 110,182 patients who have had a stroke (five ancestries, 33% non-European) and 1,503,898 control individuals, we identify association signals for stroke and its subtypes at 89 (61 new) independent loci: 60 in primary inverse-variance-weighted analyses and 29 in secondary meta-regression and multitrait analyses. On the basis of internal cross-ancestry validation and an independent follow-up in 89,084 additional cases of stroke (30% non-European) and 1,013,843 control individuals, 87% of the primary stroke risk loci and 60% of the secondary stroke risk loci were replicated (P < 0.05). Effect sizes were highly correlated across ancestries. Cross-ancestry fine-mapping, in silico mutagenesis analysis3, and transcriptome-wide and proteome-wide association analyses revealed putative causal genes (such as SH3PXD2A and FURIN) and variants (such as at GRK5 and NOS3). Using a three-pronged approach4, we provide genetic evidence for putative drug effects, highlighting F11, KLKB1, PROC, GP1BA, LAMC2 and VCAM1 as possible targets, with drugs already under investigation for stroke for F11 and PROC. A polygenic score integrating cross-ancestry and ancestry-specific stroke GWASs with vascular-risk factor GWASs (integrative polygenic scores) strongly predicted ischaemic stroke in populations of European, East Asian and African ancestry5. Stroke genetic risk scores were predictive of ischaemic stroke independent of clinical risk factors in 52,600 clinical-trial participants with cardiometabolic disease. Our results provide insights to inform biology, reveal potential drug targets and derive genetic risk prediction tools across ancestries

Experimental Study on Quantitative Application of Electromagnetic Radiation Excited by Coal-rock Fracture

A coal-rock uniaxial compression experimental investigation was conducted in laboratory. Electromagnetic radiation (EMR) and acoustic emission (AE) signals were gained during coal-rock fracture under different antenna types and arrangements. The results show that EMR excited by coal-rock fracture are broadband frequency, the EMR and AE signals are from the same source, but their generation mechanism is different. Under the same frequency band of antenna, the EMR amplitude from antenna parallel with crack plane is bigger than from antenna vertical to crack plane. Thus, EMR signals from developing crack propagates along the crack surfaces, which are principle contributions to total EMR signals and the EMR signals from antenna reflect the crack state parallel with receiving direction plane of antenna in coal-rock under uniaxial compression. A quantitative relationship between EMR frequency along the major crack plane and crack was derived by previous studies, which can be used into applications for coal-rock dynamic disaster prediction in the future

A numerical simulation study on mechanical behaviour of coal with bedding planes under coupled static and dynamic load

To investigate the bedding influence on coal mechanical behaviour in underground environments such as coal or rock burst, simulations of dynamic SHPB tests of pre-stressed coal specimens with different bedding angles were carried out using a particle flow code 2-dimensional (PFC2D). Three impact velocities of 4, 8 and 12 m/s were selected to study dynamic behaviours of coal containing bedding planes under different dynamic loads. The simulation results showed that the existence of bedding planes leads to the degradation of the mechanical properties and their weakening effect significantly depends on the angle θ between the bedding planes and load direction. With θ increaseing from 0° to 90°, the strength first decreased and subsequently increased and specimens became most vulnerable when θ was 30° or 45°. Five failure modes were observed in the specimens in the context of macro-cracks. Furthermore, energy characteristics combined with ultimate failure patterns revealed that maximum accumulated energy and failure intensity have a positive relation with the strength of specimen. When bedding planes were parallel or perpendicular to loading direction, specimens absorbed more energy and experienced more violent failure with increased number of cracks. In contrast, bedding planes with θ of 30° or 45° reduced the specimens\u27 ability of storing strain energy to the lowest with fewer cracks observed after failure

Numerical simulation of airflow distribution in mine tunnels

Based on 3D modelling of typical tunnels in mines, the airflow distribution in a three-center arch-section tunnel is investigated and the influence of air velocity and cross section on airflow distribution in tunnels is studied. The average velocity points were analyzed quantitatively. The results show that the airflow pattern is similar for the three-center arch section under different ventilation velocities and cross sectional areas. The shape of the tunnel cross section and wall are the critical factors influencing the airflow pattern. The average velocity points are mainly close to the tunnel wall. Characteristic equations are developed to describe the average velocity distribution, and provide a theoretical basis for accurately measuring the average velocity in mine tunnels. Keywords: Mine tunnel, Turbulence, Airflow distribution, Three-center arch, Average velocit

The heterogeneity and electro-mechanical characteristics of coal at the micro-and nanoscale

With regard to the mechanism of electromagnetic radiation (EMR) excited by deformation and failure of coal and rock, the present study employed the optical microscope, digital microhardness tester and atomic force microscopy (AFM) to measure surface morphology, surface microhardness and electro-mechanical characteristics, including elastic modulus and surface potential of coal. The results show that micro-mineral composition and micro-mechanical properties of coal are clearly heterogeneous. The elastic modulus values measured are 62.3 MPa-4.0 GPa and the surface potential values tested are 21.2-166.2 mV. The proportion distributions of the two parameters mentioned follow the normal distribution, which indicates the electro-mechanical characteristics of coal are clearly inhomogeneous at the micro-and nanoscales. Finally, the effects of the inhomogeneous elastic modulus and surface potential on the EMR from the microscopic perspective were analyzed. In this experiment, the change of the micro-elastic modulus and the existence of the surface potential on the coal surface were directly observed. The findings reveal the mechanism of EMR induced by deformation and failure of coal and rock

Analysis of energy accumulation and dissipation of coal bursts

Coal bursts are a serious dynamic hazard for underground coalmines, and they attract the extensive interest of studies from mining and geotechnical researchers worldwide. More recently, coal-burst incidents were reported in some Australian coalmines as a result of inadequate geological assessment of coal-burst hazards. The coal-burst process is closely associated with the accumulation of elastic energy and the rapid dissipation of kinetic energy. This paper introduces the essential geological conditions for energy accumulation, and the likely precursors for rapid energy dissipation leading to coal burst, which can be used by Australian coalmines to determine their coal-burst risk accordingly. Different energy forms and their transformations during the coal-burst process are introduced in detail in this paper. The dominant geological factors resulting in the accumulation of massive energy are analyzed, and the likely precursors associated with the instant release of elastic energy are discussed

Numerical simulation study on rheological failure characteristics of rock mass under high stress

This paper uses the RFPA numerical simulation software to establish a numerical model of the rheological failure of the rock mass under stress. Rheological failure characteristics of the body was researched, and the results shows: (1) The rupture sequence of rock rupture is from the corner to the middle. When the rock loses stability under pressure, the rock often ruptures from the corner. The corner gradually collapses and cracks. Then the cracks spread to the middle of the rock. Many cracks extending from the corners are in the rock. The central part intersects each other and eventually causes the rock to break. (2) Rock samples of different lithologies have different stress values when they break under the same confining pressure. From the experimental process, we know that granite>sandstone>mudstone. Therefore, the higher the strength of the rock, the harder the rock will be broken. (3) The weaker the plasticity at rupture, the stronger the brittleness and the stronger the sudden change of rupture. In the deep mining process, the greater the confining pressure, the more obvious the rheological characteristics of the rock, and the greater the total energy released during the rock failure process

Experimental study of coal burst risk prediction using fractal dimension analysis of AE spatial distribution

© 2020 Elsevier B.V. The sustainable and clean mining of coal is essential for Australia and the world as coal is a key energy source. However, with the increase of mining depth, many coalmines are facing potential coal burst hazards as deep mining always associated with high gravitational stress and complicated geology. More recently, the coal burst risk is highlighted by accidents happened at Austar and Appin coalmines in Australia. Assumedly due to long time mining history with relatively shallow mining depth, coalmines in Australia has no coal burst history and corresponding risk controlling plans, technics and equipment. This paper proposes a novel method for coal burst risk prediction based on fractal dimension analysis of AE spatial distribution. Besides, this paper introduces the mathematical analysis method of fractal dimension based on dimension calculation formula and MATLAB coding. Finally, obvious fractal dimension decrease of AE spatial distribution is observed in experimental study of coal samples with high burst propensity, which promises the feasibility of coal bursts prediction through AE monitoring