scholarly journals Determination of Water-Proof Coal (Rock) Pillar Height in Mining Coal Seam Group under Water-Bearing Rock Stratum

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Feng Wan ◽  
Hongqing Zhang ◽  
Peijun Zhou ◽  
Jie Guo
Keyword(s):  
Fracture Zone ◽  
Coal Seams ◽  
Rock Stratum ◽  
Pillar Height ◽  
Rock Pillar ◽  
Maximum Value ◽  
Coal Rock ◽  
Mining Coal ◽  
Water Proof

In order to determine the reasonable height of water-proof coal (rock) pillar when mining multiple coal seams under aquifer, this paper analyzes the expansion height of water-conducting fracture zone when coal seams mining. Considering the expansion law of water-conducting fracture zone in coal seams mining, two schemes of coal seams mining in upper and lower groups and one-time mining of all coal seams are designed for comparative analysis, and the height of water-proof coal (rock) pillar is determined based on the expansion height of water-conducting fracture zone. The results show that the height of water-proof coal (rock) pillar is calculated as 91.08 m when mining upper and lower groups and 105.46 m when mining all coal seams at the same time. According to UDEC numerical simulation results, the height of water-proof coal (rock) pillar is 56.08 m when mining upper and lower groups and 86.36 m when mining all coal seams at the same time. Comparing the results of theoretical calculation and numerical analysis, the maximum value is selected as the final result, and the reasonable water-proof coal (rock) pillar height is determined to be 105.46 m.

scholarly journals MODELING OF STABILITY OF SIDE ROCKS IN A COAL MASIFWITH DIFFERENT METHODS OF SUPPORT THE WORKINGS

2021 ◽  
Vol 37 (3) ◽  
pp. 28-34
Author(s):  
V. Yu. Dovhal
Keyword(s):  
Static Field ◽  
Rock Massif ◽  
Shear Stresses ◽  
Support Structures ◽  
Coal Seams ◽  
Rock Stratum ◽  
Static Loads ◽  
Flexible Support ◽  
Coal Rock ◽  
The Stability

Purpose of work. Determine the conditions of the side rocks stability in a coal massif with different ways of support coal-rock stratum to ensure safe working conditions for miners in the excavation areas of a coal mine with steep coal seams. To achieve this goal, laboratory studies were carried out on models of optical and equivalent materials. The modeling of the stability of side rocks in a coal-rock massif was carried out with the methods of support roadways with vertical timber setsand wooden crib supports: 4-point chock.On models made of optical materials in the analysis of the static field of the distribution of shear stresses in side rocks, the regularity of the change in hazardous manifestations of rock pressure, depending on the deformability of support structures, was recorded. On equivalent models of support structures, the deformation characteristics of experimental samples were determined and their effect on the integrity of the roof under the action of static loads was established. When using rigid support structures in the form of vertical timber sets made of wooden racks to protect sliding drifts, there is a deterioration in the stability of side rocks and destruction of the roof. When using flexible support structures in the form of wooden crib supports: 4-point chock, a smooth deflection of the roof and its integrity are observed. A decrease in the size of the stress concentration zone in the model of a coal-rock massif with workings after the compaction of flexible support structures located above the haul roadway, due to a change in their rigidity, when as a result of the convergence of side rocks, a smooth deflection is provided and the movement of the roof is limited. To ensure the stability of side rocks and development workings, as well as reduce the level of injuries of miners from landslides and collapses in the excavation areas of coal mines that develop steep seams, it is advisable to use flexible support structures, when using which, a smooth deflection of side rocks and their integrity in the mined-out area is ensured coal massif.

scholarly journals Mining Wastes of an Albite Deposit as Raw Materials for Vitrified Mullite Ceramics

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 232
Author(s):  
Pedro J. Sánchez-Soto ◽  
Eduardo Garzón ◽  
Luis Pérez-Villarejo ◽  
George N. Angelopoulos ◽  
Dolores Eliche-Quesada
Keyword(s):  
Particle Size ◽  
Raw Materials ◽  
Phase Evolution ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Mining Wastes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Maximum Value

In this work, an examination of mining wastes of an albite deposit in south Spain was carried out using X-ray Fluorescence (XRF), X-ray diffraction (XRD), particle size analysis, thermo-dilatometry and Differential Thermal Analysis (DTA) and Thermogravimetric (TG) analysis, followed by the determination of the main ceramic properties. The albite content in two selected samples was high (65–40 wt. %), accompanied by quartz (25–40 wt. %) and other minor minerals identified by XRD, mainly kaolinite, in agreement with the high content of silica and alumina determined by XRF. The content of Na2O was in the range 5.44–3.09 wt. %, being associated with albite. The iron content was very low (<0.75 wt. %). The kaolinite content in the waste was estimated from ~8 to 32 wt. %. The particle size analysis indicated values of 11–31 wt. % of particles <63 µm. The ceramic properties of fired samples (1000–1350 °C) showed progressive shrinkage by the thermal effect, with water absorption and open porosity almost at zero at 1200–1250 °C. At 1200 °C, the bulk density reached a maximum value of 2.38 g/cm3. An abrupt change in the phase evolution by XRD was found from 1150 to 1200 °C, with the disappearance of albite by melting in accordance with the predictions of the phase diagram SiO2-Al2O3-Na2O and the system albite-quartz. These fired materials contained as main crystalline phases quartz and mullite. Quartz was present in the raw samples and mullite was formed by decomposition of kaolinite. The observation of mullite forming needle-shape crystals was revealed by Scanning Electron Microscopy (SEM). The formation of fully densified and vitrified mullite materials by firing treatments was demonstrated.

Metrology of the photo-grid determination of fracture strain for a plate in bending

1968 ◽  
Vol 3 (2) ◽  
pp. 96-97
Author(s):  
R T Hartlen ◽  
L E Jones
Keyword(s):  
Circumferential Strain ◽  
Fracture Strain ◽  
Thickness Ratio ◽  
Grid Data ◽  
Fracture Location ◽  
Maximum Value

Aluminium plates (7/1 width/thickness ratio) were bent to fracture. Circumferential strain at fracture location (maximum value 0.26) was obtained by special plotting and extrapolation of (millimetre) photo-grid data.

scholarly journals Determination of Long Horizontal Borehole Height in Roofs and its Application to Gas Drainage

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2647
Author(s):  
Gang Wang ◽  
Cheng Fan ◽  
Hao Xu ◽  
Xuelin Liu ◽  
Rui Wang
Keyword(s):  
Numerical Simulation ◽  
Theoretical Model ◽  
Fracture Zone ◽  
Coalbed Methane ◽  
High Efficiency ◽  
Gas Drainage ◽  
Methane Drainage ◽  
Working Face ◽  
Variation Characteristics

Accurately determining the height of the gas-guiding fracture zone in the overlying strata of the goaf is the key to find the height of the long horizontal borehole in the roof. In order to determine the height, in this study we chose the 6306 working face of Tangkou Coal Mine in China as a research example and used both the theoretical model and discrete element method (DEM) numerical simulation to find the height of the gas-guiding fracture zone and applied the height to drill a long horizontal borehole in the roof of the 6303 working face. Furthermore, the borehole was utilized to deep into the roof for coalbed methane drainage and the results were compared with conventional gas drainage measures from other aspects. The height of the gas-guiding fracture zone was found to be 48.57 m in theoretical model based on the bulk coefficient and the void ratio and to be 51.19 m in the DEM numerical simulation according to the temporal and spatial variation characteristics of porosity. Taking both the results of theoretical analysis and numerical simulation into consideration, we determined that gas-guiding fracture zone is 49.88 m high and applied it to drill a long horizontal borehole deep into the roof in the 6303 working face field. Compared with conventional gas drainage measures, we found that the long horizontal borehole has the high stability, high efficiency and strong adaptability for methane drainage.

scholarly journals Electrical Equivalent Circuit of Multi-Tips Pulsed Corona Discharge Reactor

2021 ◽  
Vol 348 ◽  
pp. 01014
Author(s):  
Karim Saber ◽  
Alyen Abahazem ◽  
Nofel Merbahi ◽  
Mohamed Yousfi
Keyword(s):  
Corona Discharge ◽  
Electrical Circuit ◽  
Electrical Model ◽  
Electrical Equivalent Circuit ◽  
Rls Algorithm ◽  
Estimated Parameters ◽  
Maximum Value ◽  
Pulsed Corona ◽  
Discharge Behavior

In this work, an electrical model equivalent to the corona discharge reactor has been proposed in a multitips plan configuration, in dry air at atmospheric pressure. The electrical parameters evolution of the circuit are obtained by using the identification method which is based on the least squares recursive (RLS) algorithm, the estimated parameters allow us to describe the corona discharge behavior inside the reactor. The RLS method used during the determination of capacitance and resistance is validated by the comparison between the measured and the calculated currents, the significant forms of capacitance and resistance confirm the validity of the proposed electrical model. The estimated parameters of the electrical circuit allowed us to determine the discharge power, the power delivered to the reactor and thus the energy efficiency during the discharge, this efficiency increases during the propagation of streamers towards the plane, it reaches a maximum value which is equal to 50% in the case of the fourtips- plane configuration. The energy stored in the reactor is also calculated using the electrical circuit, it increases to a maximum value of 2.6 pJ, which is a very low value compared to the energy delivered to the reactor. This work allows us to control the discharge and lost energy during the corona discharge in the case of multi-tips-plane configuration.

scholarly journals Comparative characteristics of the petrographic composition and quality of coal series С12 and С13 of the Prydniporovia Block

2021 ◽  
Vol 30 (1) ◽  
pp. 145-152
Author(s):  
Vyacheslav S. Savchuk ◽  
Vasyl F. Prykhodchenko ◽  
Dmytro V. Prykhodchenko ◽  
Valeriia V. Tykhonenko
Keyword(s):  
Volatile Matter ◽  
Matter Content ◽  
Coal Seams ◽  
Combustion Heat ◽  
Petrographic Composition ◽  
Genetic Features ◽  
History Of ◽  
Coal Composition ◽  
Technological Indices

Taking into consideration the whole history of geological development of the Western Donbas, data on composition and grade of С12 series coal involved information about the geotectonic development of the Basin. To satisfy the objectives, a system of research methods, covering petrographic, computational, statistical, chronological, comparative and other methods, has been applied. In the process of identification of the petrographic composition and grade of series С12coal on the territory of the Prydniprovia Block, and determination of lateral regularities of their change as well as change in stratigraphic section of the Lower Carboniferous, data of petrographic as well as chemical and technological indices of the coal seam c1 were generalized along with data of all seams of С13 series. The activities helped define genetic features of series С12coal as well as stratigraphic and lateral regularities of changes in the coal composition. The differences in the petrographic composition as well as in the chemical and technological characteristics of series С12 and С13 are indicative of dissimilar conditions of formation of their peat depositions. It has been determined that compared with С13 series coal, the coal of С12 series contains more humidity and fewer mineral impurities. It is characterized by higher values of sulfur content, volatile-matter content, and combustion heat. The ultimate composition of coal seams of С12series is characterized by smaller values of carbon and oxygen contents as well as greater hydrogen content. The conclusions on common features and differences in the petrographic composition as well as chemical and technological features of coal seams of С12and С13 series, and regularities of their changes over the area of the seam occurrence was assessed.

scholarly journals Cutting Mechanical Study of Pick Cutting Coal Seams with Coal and Rock Interface

2021 ◽  
Author(s):  
Chenxu Luo ◽  
Junbei Qaio
Keyword(s):  
Compressive Strength ◽  
Coal Seam ◽  
Mechanical Model ◽  
Impact Load ◽  
Strength Analysis ◽  
Strength Condition ◽  
Rock Interface ◽  
Coal Rock ◽  
Rotary Cutting ◽  
Mining Coal

Abstract Shearer provide an effect solution for mining coal, and the cutting performance of pick largely accouts for the ability of a shearer and mining performance. We conducted pick cutting coal experiments in different seam forms on the coal and rock cutting teasted. According to the rotary cutting mechanical model of single pick cutting coal seam, combined with the strength condition of coal seam and coal-rock interface, the rotary cutting mechanical model of pick cutting coal seam with coal-rock interface is established. The stress strain and strength condition of the area in and around the interface are analyzed based on the coal-rock interface crushing theory, which provides basis for further research on the cutting mechanical model of single pick crossing the coal-rock interface. According to the analysis on the ampulitude domain, the phenomenon that force increment between the pick cutting rock and uniform coal seam linearly increases with the increase of compressive strength difference between coal seam and coal-rock interface, and the load fluctuation keep a positive correlation with the compressive strength. Analysis on the signals of the pick cutting coal seam with coal and rock interface at different conditions shows that some basic properties of the cutting load changes over times. In addition, the coal seam with coal-rock interface appears larger impact load and other time-domain characteristics.

scholarly journals Field and Laboratory-based Approach for the Determination of Friction Angle of Geological Discontinuities of Malaysian Granites

2011 ◽  
Vol 28 (2) ◽  
pp. 151 ◽  
Author(s):  
R. A Ghani ◽  
T. L Goh ◽  
A. M Hariri ◽  
Y. N Baizura
Keyword(s):  
Friction Angle ◽  
Roughness Coefficient ◽  
Average Value ◽  
Peak Friction Angle ◽  
Maximum Value ◽  
Wide Range ◽  
Discontinuity Surfaces ◽  
Geological Discontinuities ◽  
Range Of Values

The basic friction angle, Φb for artificially sawn discontinuity planes for fresh granite, as determined by tilt testing, has an average value of 30º. For the natural rough discontinuity surfaces, a wide range of values have been determined for the peak friction angle, Φpeak ranging from 47º to a maximum value of 80º, depending on the joint roughness coefficient (JRC). The average values of the friction angles for the different degrees of roughness were as follows: JRC 2–4 = 58°; JRC 6–8 = 60°; JRC 8–10 = 47°; JRC 12–14 = 60°; JRC 14–16 = 71° ; JRC 18–20 = 80°.

Sign in / Sign up

Export Citation Format

Share Document