Thin Seams Research Articles

Research on Kinematics Joint Type Mobile Robot Platform for Thin Coal Seam Inspection

Due to the high labor intensity of the maintenance workers, the narrow space and harsh environments in mining process of thin coal seam, an inspection robot to adapt to the thin seam environment instead of workers for the inspection work is urgently need . In this paper, we research on a bionic joint type inspection robot motion platform in thin coal seam, and study the kinematics analysis, which is a theoretical foundation for this kind of the robot platform control.

Development and prospect on fully mechanized mining in Chinese coal mines

Fully mechanized mining (FMM) technology has been applied in Chinese coal mines for more than 40 years. At present, the output of a FMM face has reached 10-million tons with Chinese-made equipment. In this study, the new developments in FMM technology and equipment in Chinese coal mines during past decades are introduced. The automatic FMM technology for thin seams, complete sets of FMM technology with ultra large shear height of 7 m for thick seams, complete sets of fully mechanized top coal caving technology with large shear height for ultra-thick seams of 20 m, complete sets of FMM technology for complex and difficult seams, including steeply inclined seams, soft coal seams with large inclination angle, and the mechanized filling mining technology and equipment are presented. Some typical case studies are also introduced. Finally, the existing problems with the FMM technology are discussed, and prospect of FMM technology and equipment applied in Chinese coal mines is put forward.

Spontaneous caving and gob-side entry retaining of thin seam with large inclined angle

Based on the research method of combining simulation analysis with field testing by distinct element process UDEC, we have analyzed the roof deformation and failure laws and roadway support technology of gob-side entry retaining in a thin seam with a large inclined angle. The results show that during exploitation in seams with large inclined angle, rotational subsidence of the main roof under the gob area is small and can maintain balance, so there is no need to provide artificial permanent support resistance for the main roof near the upper side to control rotational subsidence. Obstructed by the dense scrap rail, waste rock from the immediate roof caving slides from the upper gob area to the lower area and fills it, which strikes a balance between the immediate roof under the goaf after it fractures into large pieces and filling waste rocks.

Study on Technology of Mechanized Mining in Extremely Thin Coal Seam

The reserve proportion of thin coal seam in Sichuan Province is as high as 60%, of which the extremely thin coal seam mines with the coal thickness less than 0.6m take up 34.3% in the total number of Sichuan coal mines. Exploiting the extremely thin seam called Xiayuantan in Laoyingyan Coalmine confronts so many problems, such as small working space in coalface, difficulty in transporting, high labor intensity, poor production, and low stoping efficiency. Aiming at these problems, this paper puts forward the conventionally-mechanized coal winning technology, investigates the selection, matching, organization and management of equipment in mechanized mining face. Moreover, it demonstrates the rationality of associated equipment selection, that is, MG100-TP off-pan shearer is suitable for exploiting the extremely thin coal seam mechanically. There are less workers in the mechanized mining face, the raw coal production and the stoping efficiency have been enhanced, the roof condition of workface has been improved,serious injury and any other more serious accidents have been completely eradicated. The technology obtains remarkable economic effects and safety benefits.

Significant shortening by pressure solution creep in the Dwyka diamictite, Cape Fold Belt, South Africa

The Dwyka diamictite preserves a record of horizontal shortening related to the development of the Cape Fold Belt at subgreenschist conditions. This shortening was accommodated by folding and thrust faulting, but pressure solution may also have contributed significantly to bulk deformation. Cleavage within the Dwyka group is, in the studied part of the Karoo Basin, subvertical to moderately south dipping, and approximately axial planar to regional folds. The cleavage is anastomosing, leading to the development of ‘tombstone cleavage’, and defined microscopically by thin seams of fine grained dark material. X-ray diffraction analyses show that the diamictite matrix is made up of quartz, feldspars, muscovite and chlorite. Element maps further indicate that the cleavage is defined predominantly by phyllosilicates and minor oxides, implying that it is made up of relatively insoluble material and hydrothermal alteration products. Overall, the cleavage therefore formed by dissolution and removal of mobile elements. This indicates that pressure solution likely accommodated a significant component of shortening during the Cape Orogeny, and provides an example of low temperature cleavage development during orogenesis.

Analysis of Inducing Factor of Thin Seam Rock Burst in Xinxing Mine

For occurring frequent thin seam rock burst disasters in deep mining stage in Xinxing Mine, through summarizing the mineral basic geological and mining conditions, on this basis, analysing the occurrence characteristics of rock burst with statistical method in Xinxing Mine, analyzing the inducing factors of thin seam rock burst, and through FLAC3D roadways along on 41,051 workface exploitation right beside left stacks of rock burst was simulated, and made a rock burst prevention focus for the impact of land pressure control system provides an effective basis. On thin hard coal burst prevention of important guiding significance.

Numerical Simulation on the Stress Distribution of Thin Seam Containing Iron-Sulfide-Cores

Fast Lagrangian Analysis of Continua in three Dimensions was adapted to establish numerical model of thin seam with Iron-sulfide-cores, based on the conditions of thin seam in Yanzhou Mining Area, and the influence of existing cores or not, cores in different positions, cores contents on mine pressure was studied. The results showed that, stress concentration and plastic zone is more easily to be formed in the coal around cores. When there are cores in coal, the bahaviors of abutment stress foreside the working face have no significant differences, the abutment stress curve is fluctuation and width or range of plastic zone little changed, but the boundary of plastic zone is fuzzy and radial. The boundary of plastic zone has some difference with the increasing of cores contents, but other macroscopic mine pressure behaviors has no significant differences. It is helpful to understand spalling mechanism of iron-sulfide-cores in thin seam.

New development of longwall mining equipment based on automation and intelligent technology for thin seam coal

The paper introduced complete sets of automatic equipment and technology used in thin seam coal face, and proposed the comprehensive mechanization and automation of safe and high efficiency mining models based on the thin seam drum shearer. The key technology of short length and high power thin seam drum shearer, and new type roof support with big extension ratio and plate canopy were introduced. The new research achievement on automatic control system of complete sets of equipment for the thin seam coal, which composed of electronic-hydraulic system, compact thin seam roof supports, high effective shearer with intelligent control system, and characterized by automatical follow-up and remote control technology, was described in this paper.

Key Parts Structure Optimum Design of Plow

Our country has abundant coal resources, thin seam can reserves 20% of all can be occupied. But , with adverse circumstances, thin coal seam mining has not yet been fully realized automation. Plough is a kind of mining equipment with shallow-frustum, Low mining height, multi circulation.Its simple structure in thin coal seam mining is a unique advantage. Along with the plough development to high-powered, high speed to dig, automation direction, and with its reliable performance problems appear more prominent, it is badly in need of further research and discussion. In order to improve the reliability of plough, expand the scope of use plough, this paper applied the method of virtual prototype of the plough structure strength analysis. Taking a coal company designed BT plough as project object, the joint simulation environment is been established by Pro/E,ANSYS and ADAMS.by using corresponding modal interface technology. At last rigid-flexible coupled model has been formed in ADAM.

Study on Technology of Simultaneous Coal Mining and Gas Drainage of Thin Coal Seam in Laoyingyan Mine

In order to improve production safety and the gas utilization in highly gassy coal mines, based on thin seam, poor gas permeability and low gas content in thin seams in Laoyingyan mine, the migration paths and abundant region of pressure-relieved gas in gob was studied by means of the strata displacement theory as well as movement regularity of gob gas. Simultaneous production system of coal mining and gas drainage was established in Laoyingyan mine, comprehensive gas drainage methods was adopted such as gas drainage method of highly-located roof crossing hole and the gas drainage method from gob. The results showed that gas drainage volume is 7.2m3/min, gas drainage efficiency was 36.3%, the phenomenon of gas-over-limit was eliminated. It was implemented that the gas resource safe, high efficient and green simultaneous coal mining and gas drainage under the premise of safe production of coal resources.

New development of sets equipment technologies for coal mine long-wall 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 parameters optimization and three-dimensional (3D) dynamic design method were presented. On the practical side, this paper outlined 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 roof-fall and collapse, and hydraulic support stability were investigated preferentially in 5∼7 m coal seam longwall mining. The application of equipment 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.

Thin Laser Weld Seam Feature Extraction on Industrial Production Line

The study proposes a robust method to extract the line structured light stripes in industrial environments. The line structured light stripe is projected onto the laser weld seam to be measured by a projector, and deformation of the stripe is detected by a CCD camera with industrial microscope lens. An image processing method that can efficiently locate the deformation of the stripe in the image plane is presented. Finally, the method is applied to two kinds of laser weld seam specimen applications, and excellent performance is shown by some experimental results.

The Research on Reasonable Support Capacity of Workface in Coal Seam with Thin Upper Cover

The showing of ground pressure is severe in workface of coal seam with thin upper cover, due to the thin upper rock seam and the action of upper incompact cover. Generally, the thin cover coal seam with 90m upper cover can be defined as Coal seam with thin cover. The result of simulation experiment for workface with thin cover and 5m mining height shows that under overburden pressure, the step subsidence is obvious, and balanced structure is still formed in surrounding rock, under overburden pressure. But the shape and form of balanced structure are different from the balanced structure formed upper coal seam with normal buried depth. There appears step or dislocation between the upper rock seam in workface and the balanced structure in the mined-out area, and the quantity of dislocation is 2m. But no step subsidence appears in the simulation for the workface with thin cover and 3m mining height. So the mining height is the key for the step subsidence. This paper gives out the movement model of surrounding rock upper the workface in thin cover coal seam and chooses 1 MPa as the support capacity for the first workface of Gaotouyao Colliery based on calculation.

Study and Application on the Parameters of Gob-Side Entry Retaining in Thin Seam with Limestone Roof

The gob-side entry retaining technology can be used to not only solve the problem of intensity in successive mining but also reduce the 10,000 tons' drivage rate and improve the coal recovery. Based on the established roof cutting mechanical model, the method of numerical simulation is used to determine the technical parameters of gob-side entry retaining in one coal mine. The reduction in cross-section of the roadway is 10.8% according to the field observation, which shows that the gob-side entry retaining has obtained preferable results and fulfilled the demand of safe production in the face.

Study on Movement Law of Overlying Strata during Shallow Thinner Seam Mining in Shendong Mining Area

Given the particularity and the first time for shallow thinner seam mining in Shendong mining area, the overlying strata movement law during shallow thinner coal seam mining has been studied in this paper based on the fully mechanized thinner coal face of NO.71301 in Shi Getai coal mine, resorting to observation on spot, numerical simulation and other methods. Through research, the important laws and features had been obtained, such as, initial pressure step, periodical pressure step, the obvious partition of periodical weighting, the unitary elasticity distribution of front abutment pressure, and the stress shell morphology over the mining rock, which provides important characteristic for roof control and foundation for the powered support selection.

Analyses of Actual Measurement and Numerical Simulation on Gently Inclined Thin Seam

Based on the numerical simulation method and actual measurement analyses, characteristics of working face mineral pressure of the River Mouth Mine has been analyzed and this paper has obtained the following results: First weighting step of the main roof is 23.2 m, the average dynamic pressure coefficient is 1.54~1.74, mine strata behaviors is fiercer; hydraulic prop’s average working resistance is 45.72 KN of each, which indicates hydraulic prop’s working resistance has larger surplus coefficient, some measures should be taken to increase utilization ratio; advanced support length of return airway and mechanical roadway should reach to 30 m, the method and results can be used to improve support pattern of working face and guide safety production.

Digital Design of Planetary Gear Mechanism of Thin Seam Shearer Cutting Department

Planetary gear mechanism has compact structure,high single-stage transmission ratio,high loading capacity and efficiency. The volume of planetary gear mechanism influenced coal loading efficiency of thin seam shearer drum.With regard to this, digital product model,digital simulation and simulation were combined to design the planetary gear mechanism of shearer cutting department. It can improve designing efficiency and reliability of planetary gear mechanism，and enhanced coal loading efficiency of shearer drum.

Reliability Study of Thin Seam Hearer Cutting Unit under Multi-Condition

Application of a variety of software construct co-simulation environment, establishment of model of thin seam shearer cutting unit rigid-flexible coupling multimode system, do correctness verification to model from speed characteristics and mechanical properties. Simulation by loading, get characteristics of principal stress and weak links of key parts. Compared to the prototype model simulation under multi-condition, got the best traction speed of shearer when working in a particular coal seam. Axis of the planet given to different materials to comparative simulation and comprehensive analysis, given the best materials of planetary shaft should be selected, improved the reliability of planetary axis under poor conditions.

Study on movement law of overlying strata during shallow thinner seam mining

Abstract Given the first time for shallow thinner seam mining, this paper resorted to methods of field measurement and numerical simulation to research overlying strata movement law during shallow thinner seam mining. Through research, it was obtained that 20m in front of coal wall was the region influenced by mining. In this region, advanced abutment pressure demonstrated law of single elastic. The pressure reached its peak value at coal wall and the fracture of rock beam occurred only in coal wall. When rock beam ruptured, there was no obviously deformation and other pressure behavior in roadway. As distance to coal wall increasing, pressure value was decreasing in rule of negative exponential.

Study on Joint Residual Stress Induced by Laser Beam Welding of High Strength Automobile Thin Sheet

Despite the advantages of the high energy density, high welding velocity and low deformation, some detrimental residual stresses were still introduced during the laser beam welding (LBW) process. The aim of this work was to study the magnitude and distribution of the residual stress in the LBW seam of the high strength automobile thin sheet. With the feature of applicable to the measurement of the residual stresses in the narrow area, the indentation strain method (ISM) was employed. By appropriate design of the biaxial strain rosette with the small size, the ISM was successfully used to measure the residual stress in the thin sheet LBW seam. Also, the finite element method (FEM) was used to calculate the residual stress. The comparison of the measured residual stresses through the ISM was made with those of the cutting relaxation method (CRM) as well as the FEM results. The ISM results showed that the highest tensile residual stress located at the seam centerline and exceeded to the 60 percent of the yield strength of the base metal.