The adjusting mining technology of combining fully mechanized with individual prop,rotating,hilt,irregular form,and double unit face on thin coal seam of Tianchen Mine

Analyzed the situations and characteristics of thin coal seam mining and its mining technologies,and introduced the mining innovation technology used by Tianchen Coal Mine of Zhaozhuang Coal Company of China.This innovation technology combined the fully mechanized mining with individual props,and the working face of mining is over length,irregular form and double units.The rotational adjusting mining technology on thin coal seam is also practiced in this new mining technology.The detail technologies,such as outlays of working face and ways,mining methods,equipments of cutting,transporting and sporting,have been introduced.So that,using the synthetic and creative mining tech- nologies,Tianchen Coal Mine solves the mining problems of thin coal seam successfully.

Primary study on the ＂θ＂ letter type overlying multi-strata spatial structure of mining face surrounded by mined areas

The overlying strata spatial structure academic viewpoint thinks the primary factor which controls the stope presses is the overlying strata spatial structure movement; the spatial structure above the later period coal pillar surrounded by mined areas is the most complex overlying strata spatial structure and study on its evolution law has the important realistic project significance for strata movement control and production safety. The existing research results indicate that the special structure of the first working face of the mine begins to develop lengthways from stratum movement above mined areas and extends level in the exploitation direction. From existing overlying strata spatial structure fundamental research achievement, the spatial structure above the later period coal column surrounded by mined areas have following characteristic： The spatial structure formation is from the top to the lower and from large to small. According to the findings, a formula with the use of rock layer migration angle delta was put forward to estimate isolated island coal column width on which different stratum structure is gonging to form.

Back-and-forth mining for hard and thick coal seams—research about the mining technology for fully mechanized caving working face of Datong Mine

The article introduced the key technology, mining process, and back-and-forth mining method for the caving working face of hard-thick coal seams in Datong mine, and researched this innovations process, optimized the systemic design and working face out-play, tried to perfect the caving mining technology of hard-thick coal seams further.

CFD modeling of methane distribution at a continuous miner face with various curtain setback distances

Knowledge of the airflow patterns and methane distributions at a continuous miner face under different ventilation conditions can minimize the risks of explosion and injury to miners by accurately forecasting potentially hazardous face methane levels. This study focused on validating a series of computational fluid dynamics(CFD) models using full-scale ventilation gallery data that assessed how curtain setback distance impacted airflow patterns and methane distributions at an empty mining face(no continuous miner present). Three CFD models of face ventilation with 4.6, 7.6 and 10.7 m(15, 25, and 35 ft) blowing curtain setback distances were constructed and validated with experimental data collected in a full-scale ventilation test facility. Good agreement was obtained between the CFD simulation results and this data.Detailed airflow and methane distribution information are provided. Elevated methane zones at the working faces were identified with the three curtain setback distances. Visualization of the setback distance impact on the face methane distribution was performed by utilizing the post-processing capability of the CFD software.

Prediction of face advance rate and determination of the operation efficiency in retreat longwall mining panel using rock engineering system

A new approach for prediction of face advance rete (FAR) prior to mining operation and determination of the operation efficiency after mining operation in retreat longwall mining panel is presented based upon the concepts of rock engineering system (RES). For this purpose, six longwall panels considered in Parvadeh-I coal mine. Seven major effective parameters on FAR was selected including coal mine roof rating, gas propagation, safety factor of longwall face, ratio of joint spacing to cutting depth at longwall face, longwall face inclination, panel width, floor rock mass rating. To performance evaluation of the presented model, the relationship between the average vulnerability indexes of advance operation with FAR was determined in considered panels with coefficient of determination (R2) equal to 0.884 that indicate relatively acceptable correlation and compatibility. Investigations of the research indicated that it is possible to determine the actual operation efficiency under fair conditions by a RES-based model. The inevitable reduction of FAR for each longwall panel was determined by presented model that the difference amount between the maximum possible practical face advance rate (FARmpp) and recorded actual face advance rate (FARa) indicate the operation efficiency. Applied approach in this paper can be used to prediction of FAR in retreat longwall mining panel for same conditions that can have many benefits, including better and more accurate planning for the sales market and mine operation. Also, presented method in this paper can be applied as a useful tool to determination of actual operation efficiency for other sections and extraction methods in coal mines.

Control strategy for multi-pump emulsion power station in coal mine face

Shearer and hydraulic support are matching equipments. To increase the operating speed of the shearer, the following speed of hydraulic support must be increased. This means increasing the volume of flow from emulsion power station. Analyzing the operating characteristics of hydraulic supports, the number of simultaneously operating supports is obtained by means of pressure parameter and time history at a certain time, which is a theory base for development of control system to multi-pump emulsion power station.

New development of sets equipment technologies for coal mine longwall face in China

Background of the development and achievement on sets equipment technologies for coal mine longwall face in China was reviewed initially. On the theoretical side, a coupling model of hydraulic support and surrounding rock, support pa- rameters optimization and threedimensional （3D） dynamic design method were presented. On the practical side, this paper out lined some of practical issues and discussed some relative methods and technologies. In thin seam coal longwall mining, how to lower equipment height is the first problem that should be solved. Roof pressure regularity, control of rooffall and collapse, and hydraulic support stability were investigated preferentially in 5-7 m coal seam longwall mining. The application of equip- ment for longwall mining with 5-7 m cutting height in China was concluded. The characteristics of full-mechanized top coal caving for extra thick seam coal were presented. The automation of top-caving hydraulic support and relevant equipment have achieved important breakthrough. At the end of this paper, further development of China＇s coal industry and longwall mining technologies and equipment were prospected in brief. This paper gives readers a comprehensive understanding of China＇s coal mine longwall face equipment technologies. It will give help to other countries on its coal mining development.

Longwall mining under gateroads and gobs of abandoned small mine

Due to the use of outdated mining technology or room and pillar mining process in small coal mines, the coal recovery ratio is only 10–25%. In many regions of China, the damage area caused by the small coal mines amounted to nearly one hundred square kilometers. Therefore, special mining techniques must be taken to reclaim the wasted resource in disturbed coal areas. This paper focuses on the different mining methods by analyzing the longwall panel layout and abandoned gateroad(AG) distribution in the abandoned area of Cuijiazhai coal mine in northwestern China. On the basis of three-dimensional geological model, FLAC3 D numerical simulation was employed. The abutment pressure distribution was simulated when the panel face passed through the disturbed areas. The proper angle of the inclined face was analyzed when the panel face passed through the abandoned gateroads. The results show that the head end of the face should be 13–20 m ahead of the tail end. The pillars on both sides of abandoned gateroads had not been damaged at the same time, and no large-area stress concentration occured above the main roof.Therefore, the coal reserves of disturbed areas can be successfully recovered by using underground longwall mining.

Ground pressure and overlying strata structure for a repeated mining face of residual coal after room and pillar mining

To investigate the abnormal ground pressures and roof control problem in fully mechanized repeated mining of residual coal after room and pillar mining, the roof fracture structural model and mechanical model were developed using numerical simulation and theoretical analysis. The roof fracture characteristics of a repeated mining face were revealed and the ground pressure law and roof supporting condi- tions of the repeated mining face were obtained. The results indicate that when the repeated mining face passes the residual pillars, the sudden instability causes fracturing in the main roof above the old goal and forms an extra-large rock block above the mining face. A relatively stable ＂Voussoir beam＂ structure is formed after the advance fracturing of the main roof. When the repeated mining face passes the old goaf, as the large rock block revolves and touches gangue, the rock block will break secondarily under overburden rock loads. An example calculation was performed involving an integrated mine in Shanxi province, results showed that minimum working resistance values of support determined to be reason- able were respectively 11,412 kN and 10,743 kN when repeated mining face passed through residual pillar and goaf. On-site ground pressure monitoring results indicated that the mechanical model and support resistance calculation were reasonable.

Suitable retention and recovery technology of floor coal at ends of fully mechanized face with great mining heights

Gateways at faces of great mining heights are mostly driven along the roof of coal seams.For gateway height restrictions,a 1-3 m floor coal is retained,leaving a triangular floor coal at the face ends,causing a loss of coal.In order to improve coal recovery rates and to ensure efficiency of equipment at coal mining faces,we investigated suitable retention methods and recovery technology of floor coal at face ends.The upper floor coal can directly be recovered by a shearer with floor dinting.The lower floor coal is recovered by shearer with floor dinting after advanced floor dinting and retaining a step for protecting coal sides in a haulage gateway.Field practice shows that this method can improve the coal recovery rates at fully mechanized working faces with great mining heights.

Mathematical model of electric hydraulic and powered support control system at a plough mining face

Given the actual working of a fully mechanized plough at a mining face, we have proposed a formula for running constraints between powered supports and a coal plough under assumed geological conditions of the coal face and, on this basis, established an automatic control model of powered supports for the coal plough face. We introduced the working principle of the powered support control system of the plough at the mining face. We established three advanced characteristics of this control system： response speed, reliability and easy maintenance of the system. As well, we briefly introduced, the principal function of primary and subordinate controllers and the realization of the communication system by a Single Bus. Ten controllers were constructed and tested in our laboratorium. The results show that the control model is practical and meets actual conditions. It provides a theoretical basis for designing a comouter control system for a oowered support system of a plough at a mining face.

Effect of suppressing dust by multi-direction whirling air curtain on fully mechanized mining face

A combined method of numerical simulation and field testing was adopted in this study in the interest of solving the problem of hard to control high concentrate dusts on a fully mechanized mining face. In addi- tion, the dust suppression effect of a multi-direction whirling air curtain was studied in this paper. Under the influence of the wall attachment effect, the compressed air which blows out from the two-phase or three-phase radial outlets on the generator of the air curtain can form a multi-direction whirling air curtain, which can cover the whole roadway section of a fully mechanized mining face. The traditional method of controlling dust is a forcing system with exhaust overlap which has the major disadvantage of lacking a jet effect and consequently results in poor dust control. It is difficult to form the air flow field within the range of Lp ≤ 5√S. However, due to the effect of this novel system, the radial airflow can be turned into axial airflow allowing fresh air to flow through the length of the heading. The air flow field which is good at controlling dust diffusion can be formed 12.8 m from the heading face. Furthermore, the field measurement results show that before the application of a multi-direction whirling air curtain, the dust concentration is 348.6 mg/m^3 and 271.4 mg/m^3 respectively at the roadway cross-section measurement points which are 5 m and 10 m from the heading face. However, after the application of the multi-direction whirling air curtain, the dust concentration is only 61.2 mg/m3 and 14.8 mg/m^3, respectively. Therefore, the dust control effect of a multi-direction whirling air curtain is obvious.

Similar material simulation research on movement law of roof over-lying strata in stope of fully mechanized caving face with large mining height

Similar material simulation test W9-15 101 fully mechanized caving face with was carried out in a geological model of large mining height in the Liuhuanggou Colliery, in Xinjiang Uigur Autonomous Region. The roof overlying strata movement law in the stope of a fully mechanized caving face with large mining height was studied and show that the roof overlying strata in the stope of a fully mechanized caving face with large mining height can be formed into a stable arch structure; the fracture rock beam is formed resembling a ＂bond beam＂, but it has essentially the structure of ＂multi-span beams＂ under the big structure of the stable arch. The roof overlying strata movement law in the stope of a fully mechanized caving face with large mining height is similar to that of the common, fully mechanized caving stope, which is determined by the deformation and instability of the structure of ＂multi-span beams＂. But because of the differences between the mining heights, the peak pressure in the stope of a fully mechanized caving face with large mining height is smaller while the affected area of abutment pressure is wider in the front of the working face; this is the obvious difference in abutment pressure between the stope of a fully mechanized caving face with large mining height and that of the common.

Surface Movement Regularity of Super-Wide Mining Face With Top-Coal Caving

No.4326 super-wide panel of Wangzhuang Coal Mine ( in which the fully-mechanized top-coal caving longwall mining method was used) was monitored for dynamic characteristic of surface movement. The dynamic surface movement in and after mining was predicted by using the Mining Subsidence Prediction System. The results indicate that after mining, the surface above the super-wide panel reaches a state of full subsidence, making the No.309 national highway above the panel be located on the flat bottom of the subsidence basin so that the influence of mining activity in both sides of 4326 panel on the national highway is the smallest.

Prediction Model for Gas Outburst Intensity of Coal Mining Face Based on Improved PSO and LSSVM

For the problems of nonlinearity,uncertainty and low prediction accuracy in the gas outburst prediction of coal mining face,the least squares support vector machine(LSSVM)is proposed to establish the prediction model.Firstly,considering the inertia coefficients as global parameters lacks the ability to improve the solution for the traditional particle swarm optimization(PSO),an improved PSO(IPSO)algorithm is introduced to adjust different inertia weights in updating the particle swarm and solve the fitness to stagnate.Secondly,the penalty factor and kernel function parameter of LSSVM are searched automatically,and the regression accuracy and generalization performance is enhanced by applying IPSO.Finally,to verify the proposed prediction model,the model is applied for gas outburst prediction of Jiuli Hill coal mine in Jiaozuo City,and the results are compared with that of PSO-SVM model,IGA-LSSVM model and BP model.The results show that the relative errors of the proposed model are not greater than 2.7%,and the prediction accuracy is higher than other three prediction models.The IPSO-LSSVM model can be used to predict the intensity of gas outburst of coal mining face effectively.

Technological optimization of fully mechanized caving mining face with large mining heights

Fully mechanized cave mining with large mining height is a new mining method, due to its large mining thickness and lower roadway excavation, the technology has been widely used in China＇s thick seam mining. In order to improve the top-coal recovery ratio of fully mechanized cave mining with large mining height, a study was conducted on optimizing the caving process, based on the mechanized caving face 1302N in Longgu Coal Mine. This was achieved by improving the PFC numerical calculation methods, and establishing a more accurate model system. On this basis, the recovery ratio of the top coal in different drawing intervals and technologies was investigated in order to achieve a reasonable caving process. The top-coal tracking system was used for practical surveying of the recovery ratio of top coal.

Experiment Study on Movement and Damage of Overburden Under MiningFace Crossing Fault

Based on similar material model experiment, this paper studies the subsidence difference of fault hanging wall and lying wall when mining face crosses fault and the normal relative movement regularity of a fault zone. The change in bulking coefficients of fault zone, hanging wall and lying wall are given, the difference of mean bulking coefficients of two fault walls are discussed and the dynamic development pattern of fissure zone during mining face crossing fault is obtained.

In-pit coal mine personnel uniqueness detection technology based on personnel positioning and face recognition

Since the coal mine in-pit personnel positioning system neither can effectively achieve the function to detect the uniqueness of in-pit coal-mine personnel nor can identify and eliminate violations in attendance management such as multiple cards for one person, and swiping one's cards by others in China at present. Therefore, the research introduces a uniqueness detection system and method for in-pit coal-mine personnel integrated into the in-pit coal mine personnel positioning system, establishing a system mode based on face recognition + recognition of personnel positioning card + release by automatic detection. Aiming at the facts that the in-pit personnel are wearing helmets and faces are prone to be stained during the face recognition, the study proposes the ideas that pre-process face images using the 2D-wavelet-transformation-based Mallat algorithm and extracts three face features: miner light, eyes and mouths, using the generalized symmetry transformation-based algorithm. This research carried out test with 40 clean face images with no helmets and 40 lightly-stained face images, and then compared with results with the one using the face feature extraction method based on grey-scale transformation and edge detection. The results show that the method described in the paper can detect accurately face features in the above-mentioned two cases, and the accuracy to detect face features is 97.5% in the case of wearing helmets and lightly-stained faces.

Research on relations between failure heights of overburden strata and ~] / mining face parameters and forecasting method

The commercial FEM software ANSYS was used to analyze the failure characteristics of overburden strata under the conditions of different lengths of mining faces. It was shown that the parameters of mining faces, especially the length was the important factor to the failure heights and shapes of overburden strata. Fuzzy mathematics and statistical methods were used to analyze the forecasting method of the failure height of overburden strata influenced by the parameters of mining face based on the measured data under the conditions of fully-mechanized mining of general hardness cover rocks. On the basis of these analyses, a new forecasting formula was gotten. The forecasting result conforms to the in situ measured value. The result has a very important application value in safe and high-efficient mining, and has a very important advancing function to theoretical studies.

Analysis and control of hydraulic support stability in fully-mechanized longwall face to the dip with great mining height

The working condition of the hydraulic support in working face can be divided into three kinds of situations in the following： roof fall and col,lapse with cavity, advancing support and supporting. Took single support with four-pole in Iongwall face to the dip as research object, control method was studied to avoid support instability in three situations mentioned above. Based on these researches, the major factors of influencing on support stability and its controlling measures were put forward. According to specific conditions of working face 1215（3）, which is fully-mechanized and Iongwall face to the dip with great mining height in Zhangji Coal Mine, Huainan Mining Group, the effective measures was taken to control supports stability..