Analysis and Research of Factors Affecting Coal Mining with Plough

De,2002Journal of China University of mining technologyVol. 12 No. 2Analysis and Research of factorsAffecting Coal Mining with PloughLIU Guo-bing(刘过兵), CHEN Sheng-li(陈胜利)Scientific Research Department, North China Institute of Science Technology Yanjiao, Beijing 101601, ChinaAbstract: Coal mining with ploughs is an ideal coal mining technology for thin and thinner coal seams. The existence conditions of coal seams are different for each other which affects coal mining with ploughs to differentdegrees and the application results are also different. The authors analyze the affecting factors by means ofmathematical methods. The research is useful to the wide application of ploughsKey words: coal mining with plough i affecting factor i analysisCLC number: TD 823. 95 Document code: A Article ID: 1006-1266( 2002 2-0190-04Introductionnique such as the research on the classifications ofCoal is principal energy resources in China and coal seams based on coal mining with ploughs hasaccount for 70% of its primary energy. China is rich not been made and its parameter could not be choin coal reserves but the existence conditions of coal sen. Furthermore due to experience lacking for theseams are various. Among the 95 national principal diagnosis of ploughs breakdown, its advantagescoal mining bureaus there exist thin coal seams in have not been fully known. The improper choice ofof 80plough type and the poor management level degradebureaus, and their total reserves are 67 billion tons. its advantages and stress its disadvantages whichThe recoverable reserves of thin coal seams in all the disturbs its users and leads to the difficulty of its apnational principal coal mines account for 17. 6% of plication. The existence conditions of coal seamsthe total recoverable coal reserves. Thin coal seams greatly affects coal mining with ploughs so the corexitwidely in Shanxi, Hebei, Sichuan, Neimen, responding measures must be taken to gain the expected results of coal mining with ploughzhuang etc. Therefore the mining of thin coal 2 Analysis of Factors Affecting Coal Minseams is an unavoidable and urgent problem. Coaling with ploughsmining with ploughs is an ideal coal mining technolBy taking everything into consideration,weogy for thin coal seams and accounts for a big perclassify coal seams into five types based on the deentage in many countries such as Germany Enmand of coal mining with ploughs shown in Tableland and Belgium. And it is 8% of the total coalmining yield in the principal coal production counTable 1 Classification of coal seamstries. On the other hand, the level of coalType More difficult Is Difficult I Average I3 Easy I2 Easier Iywith ploughs is quite low in China, but its potential Index o≤<22≤1<44≤1<66≤1<88≤1<10is large. Ploughs are not widely used in China because of lacking full recognition for the importance of 2.nV中国煤化工ploughs experiences for the new technique and baCNMHGportant factor affectinsic and applied researches for the coal mining tech- the use of ploughs and has a direct connection withReceived date: 2001-11-30Biography: LIU Guo-bing 1947-)male from Hebei Province, professor ,engaged in the research of coal underground mining and thin coalngLIU GUObiAnalysis and Research of Factors Affecting Coal Mining with Plough19its formation metamorphic degree cementing con- and the major joint( or crack ) is 45 and 135, thedition chemical composition etc. The harder coal unit energy consumption is the smallest and theis the greater the planing resistance and crosswise biggest, respectively when it is 90, the resistanceforce will be the poorer the stability of ploughs is the biggesthead will be and the more difficult coal mining willThe mathematical expression of index I as ahore power will befunction ofφi}1planing cutters will be worn fast and ploughs willⅠ=-①/15+10(≤90°),have a short life of useⅠ=115-2(90°<更≤180°)The mathematical expression of index I as ana. It is usually suitable for coal seams with a hardof joint factor K,i. e. the number of jointsness coefficient f<2, but it is usually very difficult per meter length in the direction of working face adand sometimes impossible to excavate f>3 coal vance, is 1Jseams with the ploughs. Hardness coefficient f isI=9K1/10+1(K1<10),generally used as the index to evaluate the planning=10(K≥10)ability in China. Researches show that the mathe2. 4 Effect of seam structurematical expression of index I for the planning abilityof a coal seam as a function of its hardness f is 1Jeam structure has a fairly great effect on coalplaning with a plough. When a coal seam does not=-2.4f+10(f≤2.5)have a caking property to the roof planing height isI=128e1.36y(f>2.5)generally 1/2-1/3 of its thickness. If there is a2.2 Effect of seam thicknessparting in coal seams the result of coal planing willResearches show that when the thickness of acoal seam is below 1. 4m it is better to use ploughsbe directly affected. When the parting is too hard orThough it is normally accepted that the maximumincludes concretions explosion is needed as a helpfulthickness of coal seams excavated by ploughs should measure. The effect will be slight when the amountof concretions is below 2. 5%be 2. 5m we should choose coal cutting techniquesThe mathematical expression of index I as aon the basis of the achieved economic profits. Thefunction of the hardness coefficient fg of partingminimum thickness of coal cutting by ploughs should1be 0. 6m. The relationship between index I andthickness h( unit: m)of coal seams is 1J=-2.25fg+10(fg≤4.0),Ⅰ=30h-14(0.5≤h<0.8),I=4e036(fg>4)Ⅰ=10(0.8≤h<1.4)The mathematical expression of index I as aⅠ=-13.33h+28.67(1.4≤h≤2.0),function of h/h in which h and h are respectivelyI=512e-2720(h>2.0)the thickness of a parting and a coal seam is 1 J2.3 Effects of joints and cracks in coal seamsI=-20h/h+10(h/h≤0.2The resistance for plough cutting is a compre=-30h/h+12(0.20.4)and developing degree and direction of joints andThe position of a parting is described in dis-cracks in coal seams, etc. Both productive practice tance d from the floor to the bottom of a partingand scientific researches have proved that the mutual The mathematical expression of index I as a func-position relations between a working face and joints tor中国煤化工and cracks in coal seams and directly affect the cutCNMHG0(a/h≤0.5),ting resistance the consumption of power the staⅠ=16(d/h-1)(0.515°)weighting length i2.6 Effect of seam floorI=5(L≤25)The floor of a coal seam affects greatly coaI=L15(2550)ment of ploughs and the advance of machines will be 2.9 effect of geological structuresnfluenced greatly. When the change in the dip anThe main geological structure affecting coalgle of coal seams is over 5 within the range of 10mining with ploughs is faults. Faults not only make15m in the inclined direction, more mechanicalseam roof lose continuity and break, but also resultbreakdowns will be resulted inin steps' occurring which will make the thicknessIf the floor is loose and soft, it is easier to causeof coal seams change and lead to the difficulties ofploughs to enter it. The harder and the smoothercoal planing. Researches and practice have provedthe floor is the more easily the ploughs will workRise-fall degree of the floor can be describedthat when the throw of a fault is smaller than 1/2 ofseam thickness and the roof and floor of coal seamswith the curvature r of face conveyors in the vertiare not too hard strong planing is acceptable. Ifdirection. The relationship between I and r is]they are very hard explosion is required. when theI=10-1.2r(r≤5°),throw of a fault is over 1/2 of seam thickness, it isⅠ=32e04159(r>5°)difficult for ploughs to pass through the fault andFloor hardness can be expressed by fd. Thelationship between I and fa is]sometimes the working face has to be movedThe effect of faults is described using the ratioI=32fa2/45-44f/45(f4≤4.5)of throw d to seam thickness h and the relationI=10(fa>4.5)ship between I and d' /h is 132.7 Effect of immediate roofⅠ=-14d/h+10(d/h≤0.5)Since the planing depth for a plough is smallⅠ=-6dh+6(0.51)where Ka is the fault factor i.e. the number of litpound rooD stands for the classification index of immed itle faults in the area of 104mate roof. The relationship between I and D is l]The relationship between I and fd, hardnes万方教据D/60(D≤30)oefficient of rock at the two walls of a fault, is 11.I U Guo- bing et alAnalysis and Research of Factors Affecting Coal Mining with Plough193I=-2.25fa+10(f4≤4)=4e0.3460(f>4)3 Applications and Conclusions2. 10 Other factors3. 1 Comprehensive quantization of affecting deWater has an effect on the transportation supgree of factorsporting and management of a working face. AThe affecting degrees of these factors are differ-quantity and air speed must be properly designed ent. We usually adopt weights to describe their imwhen a plough is used in a high-gas coal mine to bet- portance in comprehensive evaluation. They haveter send out gas and heat. For the coal seams with a different affecting degrees so a final comprehensiveshort period of coal spontaneous combustion a great evaluation index is essential. The expert markingdvance speed of working faces should be kept and method is adopted in this paper to decide the weightsthe corresponding measures should be taken to en- of these factorssure the safety of coal productionBased on their theoretical researches and practiThe effect of other factors including under- cal experiences experts make subjective judgment toground temperature on coal mining with ploughs the weight value of various levels and then makecan be divided into simpler, simple average, com- use of statistical methods to get the final weight valplicated and more complicated, shown with index ue. In order to make the objectivity and accuracy3业邮如9=0Q10qualified. The result of the factor weights is listed intively. The mathematical expression of index I as a Table 2function of Q is IJI=10-QTable 2 'The weight of the factorsStructureFactorsJointFloorMain roof Structure OthersWeight0.18350.06850.08420.14940.09730.10240.09530.04480.12210.05253.2 Comprehensive decision-makingmore, their electric motors must not be located inTechnical and economic factors should be taken working faces and miners must not work in workinto account when we discuss the possibility of using ing faces. For a thin coal seam with the suitable conploughs. If a coal seam belongs to the difficult plan- ditions we should give the priority to ploughs. Inning one some measures should be taken beforehand fact, a lot of coal seams in China are suitable forand a more powerful plough should be chosen. If a ploughs At present few ploughs are used in Chinacoal seam belojust because we are not familiar with them. As longother planing methods should be adopted in order to as we take a good attitude to ploughs and try toavoid planing problems and low economic profitsknow them perfectly better technical and economic3.3 Conclusionsprofits can be obtained. Hanqiao Coal Mine, XuzhouPloughs have many advantages such as itMiDup r is a gXample Inple structure low price, low energy consumption, ploughs. We are confident that it is bound for coaleasy reparation less coal dust high coal-block rate, mining with ploughs to have a bright prosperity inhigh production and good economic profit. Further- ChinaReferences中国煤化工[1]刘过兵陈胜利薄煤层可刨性分类研究科研报R]196CNMHG[2]刘过兵.刨煤机应用现状分析及发展前景展望J]华北矿专学报200K3)9-11[3]陈引亮.徐州矿务局使用刨煤机的实践与认识J徐煤科技99K6)35.[4]陈胜利刨煤杋回采工作面矿压显现规律J]矿山压力与顶板管理,19953):16-18[5]陈炎形府中国采煤方汯M]徐州中国矿业大学出版社1991