Abstract: Provided is a method for radially mining open-pit end slope pressed coal, including: L-shaped or U-shaped main tunnel arrangements, and radially mining; branch tunnels are formed by excavating tunnels in directions perpendicular to or obliquely crossing the main tunnel from the L-shaped or U-shaped main tunnel; In the mining method, a coal mining system and a transportation system both adopt a remote control mode, a tunneling machine excavates a tunnel to product coal; a rubber belt conveyor conveys coal; the main tunnel adopts an exhaust ventilation mode, the branch tunnels adopt a blowing ventilation mode; the lengths of the branch tunnels do not exceed a farthest control distance of a remote control system; the length of each main tunnel needs to ensure that all the end slope pressed coal is mined under the premise that the branch tunnels do not exceed the farthest control distance of the remote control system.

Abstract: An experimental method and system for simulating the evolution of reservoir fracture stress field, the experimental method comprises the following steps: (S1) preparing horizontal well fracturing model (100); (S2) applying boundary loads and constraints to the horizontal well fracturing model (100); (S3) injecting fracturing fluid or fracturing gas into a fracturing wellbore (130) of the horizontal well fracturing model (100) after loading for fracturing; in a fracturing stage, a photoelastic fringe image of the horizontal well fracturing model (100) is obtained by an optical phase shift method; the fracturing stage comprises an initial state before fracturing fluid or fracturing gas is injected and an end state after fracturing is completed. The experimental method and system can effectively simulate the whole process of horizontal well fracturing, and accurately obtain the variation law of reservoir stress field and its influence on crack propagation during horizontal well fracturing.

Abstract: Disclosed is a permanent magnet direct-drive slurry pump based on gas film drag reduction, which includes a permanent magnet motor, a main shaft, an impeller, and a valve block. The permanent magnet motor includes a housing, a stator core, stator windings, a rotor core, and a permanent magnet. The rotor core and the impeller share the main shaft, and an airflow channel is provided inside the main shaft. The impeller includes a front cover plate, a back cover plate, and blades. The blades are modularly manufactured, and blade gas jet holes and hemispherical pits are provided on the pressure surface. The airflow channel in the main shaft is communicated with the blade gas-jet holes. The valve block is disposed at the tail end of the main shaft so as to control gas exhaust and prevent liquid from entering the shaft. The present invention has such advantages as a small size, high efficiency, and strong wear resistance.

Abstract: Disclosed is a system and a method for monitoring water inrush, including: a host terminal, a field host, at least one controller and at least one electrode array. Each electrode array is placed in one borehole and to detect electric field signals of surrounding rocks around the borehole; each controller connects with one electrode array and is to control the electrode array to carry out a high-density induced polarization measurement on the surrounding rocks; the field host connects with the controller and is to send control signals to the controller, receive and process the electric field signals output by the electrode array; and the host terminal connects with the field host and is to receive the electric field signals processed by the field host, determine changes on apparent resistivity and apparent chargeability of the surrounding rocks, and determine whether there exists water inrush according to the changes.

Abstract: The present invention provides an experimental platform for simulating a coal rock disaster of a coal mine extraction, including a base device, a coal simulation device, an immediate roof simulation device, a hydraulic support and a removable impact device. The coal simulation device is fixedly disposed on the base device; the hydraulic support is fixed on the base device and is located at one side of the coal simulation device; the immediate roof simulation device is disposed above the coal simulation device and the hydraulic support; the removable impact device is disposed above the immediate roof simulation device; the immediate roof simulation device is a rectangular frame; the rectangular frame is configured to pave a bulk simulation material and an immediate roof simulation material sequentially from the bottom up; and the removable impact device can impact the immediate roof simulation material and the bulk simulation material.

Abstract: Disclosed is an underground coal preparation process adopting a water medium, comprising: feeding raw coal into a special underground compact jigging machine to discharge overflow clean coal being dewatered through a ?1 mm fixed screen and screened through a ?13 mm classifying screen, and dewatering powder clean coal with a particle size less than 13 mm to obtain powder clean coal and a centrifugate; grading jigging middling coal by means of a ?13 mm classifying screen into block middling coal and powder middling coal, and dewatering the powder middling coal to obtain powder middling coal and a centrifugal liquid; and sending produced coal slime water to a water medium classifying and separation cyclone, and the obtained coarse middling coal slime and coarse clean coal slime respectively passing through a coarse middling and clean coal slime sieve bends, and then being dewatered.

Abstract: The present disclosure discloses a multi-functional intelligent tunneling apparatus and method for simulating partial excavation of tunnel. The apparatus comprises an operating platform, a multi-functional rotary tunneling system, a precision power propulsion system, an information acquiring and processing system, a digital display control box and a slurry pumping device, wherein, the multi-functional rotary tunneling system includes a plurality of independent operating channels, and can realize multi-functional simulation of a tunnel construction process, including drilling, slurry injecting, and partial excavation under real-time monitoring; under the control of the digital display control box, the precision power propulsion system can realize the fine control of the multi-functional rotary tunneling system by means of hydraulic monitoring and preset advance distance.

Abstract: Provided is a gas-solid fluidized bed dry beneficiation process using a beneficiation density gradient, including: in a dry beneficiation system of a gas-solid fluidized bed, selecting coarse particles and fine particles; placing the coarse particles at a bottom of the dry beneficiation system, and placing the fine particles above the coarse particles, wherein the coarse particles and the fine particles are separated under an initial condition; under an effect of a gas flow, the coarse particles and the fine particles being fluidized to form a high-density beneficiation region and a low-density beneficiation region, respectively, and the coarse particles and the fine particles being mixed at a contact interface to form an intermediate-density beneficiation region; and feeding minerals to be beneficiated from an upper portion of the dry beneficiation system to pass through the low-density beneficiation region, the intermediate-density beneficiation region, and the high-density beneficiation region in sequence.

Abstract: Provided is a method for recovering room-type coal pillars by cemented filling of reserved roadways, which is especially suitable for safe and efficient recovery of left coal pillars in room-type mining faces in mining areas where the ecological system is fragile, such as in western China. In the method, by constructing reserved roadways in two adjacent rows of room-type goafs, excavating coal pillar roadways in room-type coal pillars, and finally interconnecting the reserved roadways with the coal pillar roadways to form a U-shaped working face, room-type left coal pillars are recovered. Thus, not only the workload of roadway excavation is reduced, but also the recovery ratio of the coal resources is maximized. The method provides a novel technical model for the recovery of room-type left coal pillars in mining areas, such as in western China.

Abstract: Disclosed is a permanent magnet direct-drive slurry pump based on gas film drag reduction, which includes a permanent magnet motor, a main shaft, an impeller, and a valve block. The permanent magnet motor includes a housing, a stator core, stator windings, a rotor core, and a permanent magnet. The rotor core and the impeller share the main shaft, and an airflow channel is provided inside the main shaft. The impeller includes a front cover plate, a back cover plate, and blades. The blades are modularly manufactured, and blade gas jet holes and hemispherical pits are provided on the pressure surface. The airflow channel in the main shaft is communicated with the blade gas-jet holes. The valve block is disposed at the tail end of the main shaft so as to control gas exhaust and prevent liquid from entering the shaft. The present invention has such advantages as a small size, high efficiency, and strong wear resistance.

Abstract: The present invention relates to a tri-axial mechanical test apparatus and method for simulating the process of freezing the high-pressure water into ice. The tri-axial mechanical test apparatus comprises a main body loading system, a freezing system, and a sample test system; in the main body loading system, a flange, an axial pressure piston and a pressure-bearing shell are constituted to a loading main body, and the axial pressure and confining pressure are controlled directly by a tri-axial servo tester and indirectly by an oil-water separator respectively; in the freezing system, a circumferential freezing liquid circulation channel and a base freezing liquid circulation channel are connected to an external cold source for cooling and freezing, and a dissoluble shell is provided on the periphery of the sample to ensure the shape of ice; in the sample test system, a serial of optical fiber sensors in the sample is connected to an optical fiber data collector, to measure temperature and strain.

Abstract: Disclosed is a device and method for distributed detection of straightness of a working face of a scraper conveyor based on optical fiber sensing. The device includes a broadband light source, a first optical fiber circulator array, a second optical fiber circulator array, a collimator array, a reflecting film array, a third optical fiber circulator array, and an optical path analyzer. During transmission of light emitted from the broadband light source, the light with different wavelengths is separated via several optical gratings etched on a single-mode optical fiber (SMF), and reaches reflecting films adhered to the working face of the scraper conveyor through first optical fiber circulators, second optical fiber circulators, and collimators. The light with the different wavelengths is then reflected back from the reflecting films, enters the SMF through third optical fiber circulators, and finally enters the optical path analyzer.

Abstract: A similar simulation experimental device of hydraulic energy-absorbing roadway support is provided. A similar model is placed in a model box, a roadway is excavated in the similar model, and hydraulic energy-absorbing support devices are placed in the roadway on the periphery of the roadway. Front and rear ends of the hydraulic energy-absorbing support device are connected to supporting plates, left and right sides of the model box are provided with horizontal hydraulic cylinders, and front ends of the horizontal hydraulic cylinders are connected to pressure plates. One or several cushion blocks are placed at the top of the model box, and an upper pressure plate is placed above the cushion block(s). Vertical hydraulic cylinders are installed at both ends of the upper pressure plate. An impact rod passing through the upper pressure plate is placed above the cushion block to apply vertical impact load to the similar model.

Abstract: An internally injected replacement support room-type coal pillar recovery method is provided. During the recovery, the room-type coal pillars with an aspect ratio greater than 0.6 are divided into two parts: reserved coal pillars and pre-mined coal pillars. After the mining of the pre-mined coal pillars, a cemented filling material is injected into a goaf surrounded by the reserved coal pillars, and is stabilized to replace the coal pillars for support, and the reserved coal pillars are recovered. A mechanical model of the reserved coal pillars in a support overburden stage is established based on the Winkler beam theory, to obtain displacement and stress conditions of a roof of the reserved coal pillar in a support stage. A theoretical reserve-width of the reserved coal pillars is obtained according to a first strength theory of the roof and a criterion of ultimate strength of the reserved coal pillars.

Abstract: The present invention discloses a drive system of a scraper conveyor and a control method. The drive system includes a nose sprocket, a tail sprocket, a nose sprocket drive mechanism, and a tail sprocket drive mechanism, where the nose sprocket drive mechanism is a hydraulic motor I, and the tail sprocket drive mechanism is a hydraulic motor II; and a hydraulic system that drives the hydraulic motor I and a hydraulic system that drives the hydraulic motor II include same hydraulic elements, and both include a three-position four-way solenoid directional valve, a two-position two-way solenoid directional valve, a two-position three-way solenoid directional valve, an accumulator, and an oil supplement valve group. The present invention is applicable to rapid starting and stopping of the scraper conveyor in a heavy load status while adjusting chain tension in real time, thereby resolving a power imbalance problem in a dual-drive system, and has a simple structure and a long service life.

Abstract: An intelligent detection and recognition system and method for a coal-rock interface of a mine are provided. The intelligent detection and recognition system mainly includes an intelligent lifting support fastened to the top of a shearer, a non-contact radar antenna disposed at the top of the intelligent lifting support, and an operating terminal with which the radar antenna wirelessly conducts information transmission. In an operating state, a radiation direction of the radar antenna is perpendicular to the surface of a to-be-detected coal seam, and the operating terminal is configured to acquire radar data of the to-be-detected coal seam collected by the radar antenna, and draw and display a coal-rock horizon occurrence curve according to the radar data.

Abstract: A visualization system and method for a multiphase fluids displacement seepage experiment with large viscosity difference in a complex pore structure. The visualization system includes: an injection pump assembly, a visualized complex pore model, a vacuum pressure pump and an image acquisition device; the system and method are printed by a 3D printing device to form the visualized complex pore model with at least two permeability, and displacement fluid mediums of different viscosities are injected into the visualized complex pore model through different injection pumps during an experiment, so that not only is the penetration of the same viscosity in the complex pore structure with different permeability observed, but also the displacement and plugging effect of different viscosities successively entering the complex pore structure with different permeability is realized.

Abstract: A device and method for detecting an angle of a shearer rocker arm based on optical fiber sensing. The device includes an optical system and a mechanical system. The optical system includes a broadband light source, a polarizer, collimating lenses, a gradient-rotation media plate, a polarization beam splitter, and a data processing module. The mechanical system includes a connecting base, connecting rods, a slider, a bracket, and a sensor housing. When the shearer operates, the rocker arm converts rotation angle information to linear displacement related to a gradient refractive index by using a connecting rod mechanism, and a position on the gradient-rotation media plate through which linearly polarized light produced by the optical system passes also changes. Due to an optical rotation effect, corresponding rotation angles of a plane of polarization that are formed after the light passing through the gradient-rotation media plate also vary.

Abstract: Provided is a fracturing relief method for stress concentration of remaining ore pillars in an overlying goaf, including first, performing directional fracturing on a roof to optimize the stress of the roof and reduce the source of force; secondly, performing pulse fracturing on a coal pillar to produce a crack network, weaken the stiffness of the coal pillar and reduce the bearing capacity of the coal pillar; and finally, performing pulse fracturing on a floor strata of the coal pillar to reduce the ability of transferring stress concentration thereof. A drilling machine is used for separately constructing fracturing drill holes in a roadway to a set depth at an interval in a direction oblique to the coal pillar in an upper goaf. The roof, the coal pillar and the floor can be fractured by an oblique fracturing hole in a sublevel retreating manner. The position of the directional fracturing of the roof is approximately 1 m above the middle of a main roof above the coal pillar.

Abstract: Disclosed is an interference protection device and method for a hydraulic support and a cutting part of a shearer. The device includes: a plurality of dust-proof cases evenly and fixedly provided on a surface of one side of a hauling part of the shearer that faces away from a coal wall, and a dust-proof housing fixed on the hydraulic support. A first ultrasonic transducer and a flash lamp are fixedly provided in each dust-proof case, and a second ultrasonic transducer, a receiver, and a data processing module are fixedly provided in the dust-proof housing. The data processing module is electrically connected to the second ultrasonic transducer and the receiver separately, the first ultrasonic transducers and the flash lamps are all electrically connected to an external single-chip microcomputer, and the data processing module is electrically connected to a hydraulic support control computer.