In-situ experimental study on hydro-borehole technology application to improve the hard coal excavating techniques in coal mine (original) (raw)
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Application of Water Jets in Coal Mining
1976
Water is one of the natural erosion agents which through time has changed the face of the earth. Application of this principle to remove earth and rock by man is a long established technique. This paper briefly describes the changes in technology which have brought the application of water jets from the slow erosion of soil to the point where in Canada some 3,400 tons per shift are currently mined in a coal mine using high pressure water jet technology. The use of water jets has shown sufficient promise that there are several research programs currently being funded by the U.S. Bureau of Mines and other Federal agencies in the field of excavation technology. Three current areas of water jet mining are described. The first is the use of water at 10,000 psi as a modification of the cutting head of a longwall mining machine. The work which is being carried out at the University of Missouri is briefly described with the rationale for the jet parameters chosen for the experimentation. The second method of mining is a project currently under way in Canada where in a seam 50 ft thick and dip ping at an angle of some 40 degrees, a low pressure, high volume flow rate up to 1,500 gallons per minute water jet system produced up to 3,400 tons per manshift. The third method of mining is an experimental program being carried out by Flow Research, Inc. in Washington state. With this method coal is mined from underground seams to boreholes driven from the surface, coal being reamed to the borehole by high pressure water jets and crushed in the bottom of the borehole prior to being pumped out of the borehole for ex ternal usage. This method does not, therefore, require access to the underground.
Coal Mining under Water-containing condition and it's Research Status and Trend
Proceedings of the 2016 5th International Conference on Energy and Environmental Protection (ICEEP 2016), 2016
The one core content of Green mining technology is how to achieve coal mining under water-containing, which means implementing efficient exploitation of coal resources and protecting the valuable water resources in coal mining, and is the trends and requirements of the development in the coal mining area. Coal mining under water-containing is important, and we should determine the mining upper limit and choose the reasonably mining method according to the specific hydrogeological conditions. The achievement in coal mining technology with water protection is summarized systematically, and its present theories are overall summed up and evaluated by using the method of comprehensive analysis after reviewing the published literature in recent years. The research will provide a reference for further research in this filed.
Cutting Resistance Laboratory Testing Methodology for Underwater Coal Mining
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The bucket-wheel dredge “Kovin I” for underwater coal mining with bucket-wheel type UCW-450 has been in operation for over 20 years. Based on analyzing the bucket-wheel dredger performance, productivity, maintenance costs, and reliability, a rational decision was made: to rehabilitate the most essential parts of the dredge, including the bucket wheel and the gearbox. However, the selection and construction of the excavator parts were performed on the ground of available laboratory data for digging resistance. The data itself was determined by the testing methodology that did not include the influence of surrounding water pressure at a certain depth of mining. According to the previous findings, it was necessary to develop a specific research and testing program that would involve appropriate laboratory testing of the geomechanical parameters. These were to represent the influence of hydrostatic water pressure on the working environment—coal. Nevertheless, geomechanical laboratory re...
Hydraulic fracturing in underground coal mines
2008
The success of hydraulic fracturing application in stimulating gas drainage from coal seams is influenced by the ground stress conditions and the effective installation of straddled packers. A total of five holes were drilled in the Bulli Seam in a mine (Mine A) and tested for increased gas stimulation by hydraulic fracturing. Parameters examined included casing material integrity for cutability and ability to resist the external collapse during grouting and hydraulic fracturing. Changes made to the injection pressure, casing wall thickness, slot orientation (circumferential instead of axial) and controlled pressure release rate post-treatment improved the hydraulic fracturing treatment. However, the water management challenges of the test site remained inconclusive because of the location of trial site in the coal seam deposit.
Arabian Journal of Geosciences, 2019
Coal mine formations are becoming increasingly threatened by water inrush accidents resulting from high-pressure water conditions in limestone formations below mines with increasingly greater mining depths. This paper focuses on the floor of a deeply buried coal seam and the high-pressure fully mechanized mining faces of the Chensilou Coal Mine in China. Based on systematic observations and analysis of the geological and hydrogeological conditions in the study area, this study conducts theoretical analyses, numerical simulations, and underground observations in a comprehensive manner. Accordingly, a systematic and substantive investigation of the deformation and failure of the deep mining floor and the water inrush mechanism (i.e., the high hydraulic pressure within ash-filled fissures) in the Chensilou Coal Mine is carried out. The burial depth is deeper than 761.4 m, and the water pressure in the limestone of the Taiyuan Formation exceeds 4.95 MPa. Furthermore, the mining depth of the working face is 34.25 m. Based on data on water inrush events and subsurface mining failure depth, the water inrush mechanism in the floor of the coal seam in the Taiyuan Formation is analyzed. The end hole depth of the working face is composed of the L8 limestone, and transient electromagnetic detection technology is used to test the grouting effect of the working face floor and ensure the mining safety of the three working faces tested in this study.
Scientific Reports
The Karadon mine, where field studies were carried out, is located in the north west of Turkey and is considered to be a highly gaseous coal mine. Explosives and ignition systems used in underground coal mines are determined by laws, statutes, regulations and strict rules. Restrictions arising from legal requirements, such as restrictions on charging and stemming lengths and blasting agents to be used, make the use of well-known tunnel blasting techniques difficult or sometimes not possible. In such cases, the designs made with the equations given in the literature must be revised and rearranged. The objective of this study is to recommend solutions to the blasting difficulties that are encountered in gaseous underground coal mines in which there are limitations arising from legal requirements. This study summarizes and analyses the blasting practices currently employed at Karadon mine along with their disadvantages. New blasting designs were then made using the methods suggested in...
2004
This paper shows the estimate technological parameters for borehole hydro-production of sand by technical deep drilling slim well differently diameters, where are determinate calculation of radius of jet for selects hydro-monitor, the effect of hydro-caving, caving capacity, hydro-transport of pulp and drawings of the most important parts of necessary equipment for exploitation at the mining field exemplified by experimental borerhole hydro-mining of underlying quartz sand at surface open pit mine of coal named the Polje-D in Kolubara. Summary With organizing the excavation technology of loose raw materials through the boreholes, considering the complexity of technological operation, the most important thing is to calculate technical-technological parameters of exploitation and to make an optimal selection of pump aggregate, pipe line and pulp line, and also to project and construct the equipment for drilling and obtaining of concrete deposit conditions since there is no serial prod...
Design Protocols of Cavities Created by Waterjet Borehole Mining of Thin-Seam Deposits
2015
The economic extraction of thin-seam coal deposits are often problematic due to several significant limitations associated with conventional mining methods, operating practices, and equipment. It appears that the most prudent way to extract these resources in a more economical way is through the development of technology to remotely extract these resources from the surface, where waterjet borehole excavation represents a novel approach. There are a number of technical challenges that must be overcome to advance the concept of in-situ waterjet borehole mining of non-soluble resources to a commercially viable stage. Paramount among these include the continued technical advancement of drilling and excavation systems, the mechanisms used to crush, bail, and transport cuttings from the borehole, the required instrumentation to effectively control and monitor the mining process, and a technical understanding between cavity formation and stability for a given set of operating characteristi...
Fuel, 2019
Gas outburst is a serious disaster in deep mining. In this paper, we first study the effect of water content on gas outburst, and found that increasing the water content of coal can significantly reduce the elastic modulus and uniaxial compressive strength, which is beneficial in reducing the peak stress concentration in the roadway and pushing the peak stress deeper. We also found that by increasing the water content of the coal seam, the firmness coefficient increases, while the initial speed of gas diffusion decreases simultaneously. Increasing the water content of the coal seam can also change the Langmuir adsorption constant of coal, reduce the a value of the limit adsorption capacity, increase the b value of the adsorption capacity, and reduce the amount of desorption gas in the coal. These studies indicate that increasing the water content of coal can significantly reduce the risk of gas outbursts. To increase the water injection volume, the technology of promoting coal seam infusion by blasting has been proposed. Blasting promotes equilibrium distribution in the stress field and generate new fractures, which promotes the water injection. In the 8th coal mine in the Pingdingshan coal field, the test results indicate that after loosening blasting, the water injection of a single borehole increased by an average of 54.6 times under the injection pressure of 3-7 MPa. The water content of coal is improved significantly, and the prediction index value of the gas outburst is reduced significantly. This technology is important for gas control in similar coal mines.
Analysis of the Cuttability of Coal for Continuous Miner
In this paper a practical approach is presented to analyse the coal cuttability of continuous miner due to cutting action of a tool bit. An experiment was performed on the shaper machine using conical tool bit to simulate the cutting action of the tool bit of the excavating machines. Cutting parameters like depth of cut and attack angle were varied and its effect on the amount of coal removal was observed for the efficient cuttability of the mechanical excavator.