外文资料原文High Productivity —A Question of Shearer LoaderCutting SequencesK. Nienhaus, A. K. Bayer & H. Haut, Aachen University ofTechnology, GERR ecent l y, t he focus in underground longwal l coal mi ni ng has been on i ncreasi ng t he inst al l ed m ot or power of s hearer loaders and armoured face conve yors (AFC), m ore sophi st i cat ed support cont rol s yst em s and l onger face l engt h, in or der to reduce cos ts and achi eve hi gher producti vi t y. These efforts have res ul t ed i n hi ghe r out put and previ ousl y uns een face advance rat es. The t rend t owards“bi gger and bet t er” equi pm ent and l a yout schem es, however, i s rapi dl y neari ng the li mi t at i ons of t echni cal and economi cal feasi bi li t y.To reali se furt her producti vi t y i ncre as es, organi sat ional changes of l ongwall m i ni ng procedures l ooks l ike the onl y r easonabl e ans wer. The benefit s of opt i-m is ed s hearer loader cutt i ng sequences, l eadi ng t o bett er perform ance, are di s cus sed i n t hi s paper.IntroductionsTradi ti onal l y, i n underground l ongwal l m i ni ng operati ons, s hearerloaders produce coal usi ng ei ther one of t he fol lowi ng cutt ings equences: uni-di recti onal or bi-di recti onal c ycl es. Besi des t hesepre-domi nant m ethods, al t ernat i ve mi ni ng c ycl es have al so beendevel oped and s uccessfull y appli ed in underground hard coal mi nes al l over t he worl d. The hal f-web cut ti ng c ycl e as e.g. uti liz ed i n R AG Coal Int ernati onal’s Twent ym i l e Mine in Colorado, US A, and t he“Opt i-C ycl e” of M atl a’s S out h Afri can short wal l operati on m ust bem enti oned i n t hi s cont ext. Ot her mi nes have al so t est ed s i mi l ar but modi fi ed cut ti ng c ycl es res ul ti ng i n i m proved out put, e.g.im provem ent s i n t erms of product iv-it y i ncreas es of up to 40 % are thought possi bl e。

Whereas t he m enti oned mi nes are appl yi n g t he al t ernat i ve cut ti ng m et hods accordi ng to thei r spe-ci fi c condi ti ons, –e.g. s eam hei ght or equi pm ent used, –t hi s paper looks s ys t em at i call y at t he di ffer-entm et hods from a generali s ed poi nt of vi ew. A det ail ed des cripti on of t he mi ni ng c ycl e for ea ch cut ti ng t echni que, i ncluding t he i ll us t rati on of producti ve and non-prod ucti ve c ycl e ti m es, wi ll be foll owed b y a bri ef present ati on of t he perform ed product i on capacit y cal cul ati on and a summ ar y of t he t echni cal res t ri ct ions of each s ys t em. S t andardi sed equi pm ent cl as ses for di fferent seam hei ghts are defined, aft er the m ostsuit abl e and most producti ve mi ni ng e qui pm ent for each cl as s ares e-l ect ed. Bes i des t he t echni cal param e t ers of t he s hearer l oader and the AFC, t he l engt h of t he l ong-wal l face and t he speci fi c cut ti ng energ y of t he coal are t he m ai n vari abl es for each hei ght cl as s i n t he model. As a resul t of t he capaci t y cal cul ati ons, the di ffer ent shearer cut ti ng m et hods ca n be graphi call y co mpared in a st andardi s ed wa y showing t he producti vi t y of each m ethod. Due t o the gene ral char-act er of t he m odel, pot enti al opt im i s at i ons (res ul ti ng from changes i n t hecut ti ng c ycl e and t he benefi ts in t erm s of hi gher producti vit y of themi ni ng operati on) can be derived.State-of-the-art of shearer loader cutting sequences The quest i on “Why are di fferent cut ti ng s equences appli ed i n longwal l mi ni ng?” has to be an-s wered, before di s cuss ing t he si gni fi cant charact eristi cs i n t erm s of operat ional procedures. The m aj or const rai nt s and reas ons for or agai nst a s peci al cutt ing m et hod are the seam hei ght and hard-ness of t he coal, t he geot echni cal param et ers of the coal seam and t he geol ogi cal s ett ing of the mi ne infl uenci ng t he ca vi ng properti es as well as t he s ubsi dence and especi all y t he l engt h of t he l ongwal l fa ce. For each mi ning envi ronm ent the appl i cat i on of eit her s equence result s i n di fferent product ion rat es and consequentl y a dvance rat es of t he face. The coal fl ow ont o t he AFCis anot her poi nt t hat vari es l ike the l oads on the shearer loader, especi all y t he rangi ng arm s and t he st ress es and t he wear on t he pi cks.A thorough anal ys i s is neces sar y t o choos e t he bes t-suit ed mi ni ng c ycl e; therefore, general sol ut ions do not guarant ee opti m al effi ci enc y and producti vi t y.A cat egoriz at ion of shearer loader cut ti ng s equences is real ised b y four m aj or param et ers . Fi rst l y, one can s eparat e bet ween mi ni ng m et hods, whi ch m ine coal i n t wo di rect ions – m eani ng from t he head t o the t ai l gat e and on t he ret urn run as well–or i n one di recti on onl y. Secondl y, t he wa y the m i ni ng s equenc e deal s wit h t he s it uat i on at the face ends, t o advance face l i ne aft er ext ract-ing t he equi val ent of a cut ti ng web, is a charact eris ti c param et er for each separat e m ethod. The nec-essar y t ravel di st ance whil e sumpi ng vari es bet ween t he s equences, as does t he t i m e needed t o per-form t hi s t ask, t oo. Anot her as pect defi ning t he sequences i s the proport ion of t he web cut ti ng coal per run. Whereas t radit ional l y t he ful l web was us ed, t he i nt roduct i on of m odern AFC and roof s up-port autom at i on cont rol s ys t em s al l ows for effi ci ent operat i ons usi ng hal f web m et hods. The fort h param et e r i denti f yi ng st at e of the art s hearer l oader cut ti ng s equences is t he openi ng creat ed per run. Other than t he parti al or hal f-openi ng m et hod l i ke t hos e us edin Matl a’s “Opt i-C ycl e”, t he cut ti ng hei ght i s equal to the com pl et e s eam hei ght i ncl udi ng parti ngs and s oft hangi ng or foot wall m at eri al.Bi-directional cutting sequenceThe bi-directional cutting sequence, depicted in Figure 1a, is characterised by two sumping opera-tions at the face ends in a complete cycle, which is accomplished during both the forward and return trip. The whole longwall face advances each complete cycle at the equivalent of two web distances by the completion of each cycle. The leading drum of the shearer cuts the upper part of the seam while the rear drum cuts the bottom coal and cleans the floor coal. The main disadvantages of this cutting method are thought to be the unproductive time resulting from the face end activities and the complex operation. Therefore, the trend in recent years was to increase face length to reduce the relative impact of sumping in favour of longer production time.外文资料译文Uni-directional cutting sequenceIn contrast to the bi-directional method, the shearer loader cuts the coal in one single direction when in uni-directional mode. On the return trip, the floor coal is loaded and the floor itself cleaned. The shearer haulage speeds on the return trips are restricted only by the operators’ movement through the longwall face, or the haulage motors in a fully automated operation. The sumping procedure st arts in near the head gate, as shown in Figure 1b. The low machine utilisation because of cutting just one web per cycle is the main disadvantage of the uni-directional cutting sequence. Besides the coal flow can be quite irregular depending on the position of the shearer in the cycle.Half web cutting sequenceThe main benefit of half web cutting sequences is the reduction of unproductive times in the mining cycle, which results in high machine utilisation. This is achieved by cutting only a half web in m id face with bi-directional gate sequences as shown in Figure 2a. The full web is mined at the face ends, with lower speeds allowing faster shearer operation in both directions in mid seam. Beside the realisation of higher haulage speeds, the coal flow on the A FC is more balanced for shea r e r loader trips in both directions.Half-/partial-opening cutting sequenceThe advantage of the half- or, more precisely, partial- opening cutting sequence is the fact that the face is extracted in two passes. Figure 2b shows that the upper and middle part of the seam is cut during the pass towards the tailgate. Whereas the last part of this trip for the equivalent of a ma-chine length the leading drum is raised to cut the roof to allow the roof support to be advanced. On t he return trip the bottom coal is mined with the advantage of a free face and a smaller proportion of the leading drum cutting coal; consequently leading to less restrictions of the haulage speed due to the specific cutting energy of the material. The shea rer sumps in mid seam near the head gate to the full web without invoking unproductive cycle time. Like for the trip the tailgate the leading drum has to be lowered a machine length ahead ofthe main gate.Production capacity calculationsA theoretical comparison of the productivity between different mining methods in general, or in this case between different shearer loader cutting cycles, is always based on numerous assumptions and technical and geological restrictions. As a result, this production capacit y calculation does not claim to offer exact results, although it does indicate productivity trends and certain parameters for each analysed method.The model works with so-called height classes varying the seam thicknesses between 2m and 5m in steps of 50cm. Equipment is assigned to each class, having been selected by looking at the best-suited technical properties available on the market [4]. Apart from the defined equipment, it is assumed that the seam is flat and no undulations or geological faults oc cur. In the model, the ventilation and the roof support system represent no restrictions to the production. Since the aim of this model is to show ways to further increases in longwall productivity, the calculation is based on a fully automated system with no manual operators required at the face. The haulage speed of the shearer is therefore only restricted by the AFC capacity, the cutting motors and the haulage motors respectivel y.The variable parameters in this comparison of the four cutting sequences are, (besides seam thick-ness) the specific cutting energy of the coal to be cut and the length of the longwall face. The former varying between 0.2 and 0.4kWh/m³, the latter between 100m and 400m in 50m intervals. The 100m shortwalls were deliberately sel ected, since they are coming more into focus for various reasons. Geotechnical aspects, like e.g. the caving ability of the hanging wall and faults, restrict long-wall panels in many places to maximum face lengths of 150m or less, like in South Africa and Great Britain. For this reason, a detailed analysis of the potential of such longwalls is deemed appropriate.ConclusionsIn recent years much effort has been put into the optimisation of longwall operations to increase productivity and efficiency. In many cases the emphasis of these improvements was mainly focused on the equipment, e.g. increased motor power or larger dimensions of AFC’s. The organisational aspect has sometimes been neglected or did not rank as high on the agenda as other topics. In this paper, it has been demonstrated that the selected mining method has a significant impact on the achievable productivity.In a theoretical model four cutting sequences have been compared to each other while varying seam thickness, face length and coa l properties in terms of specific cutting energy.For each seam or height class a defined set of equipment was usedwith consistent restraints. Though each mine is unique, some general conclusions can be drawn anal ysing the capacit y model. Under the restrictions of the model the half web cutting sequence offers the highest output of all anal ysed methods fol-lowed by the half-opening mode. Depending on the face length, the bi-directional cutting method has advantages compared to the uni-directional sequence in terms of higher productivity.外文资料译文高效生产—一个关于采煤机截割的次序的问题目前, 地面下长壁采煤法致力于增加安装在采煤机和甲板输送机的电机功率, 以及更先进的支架控制系统和增加工作面长度,以达到减少费用和取得较高的生产效率的目的。