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1、ROOM-AND-PILLAR METHOD OF OPEN-STOPE MINING空場采礦法中的房柱采礦法Chapter 1.A Classification of the Room-and-Pillar Method of Open-Stope Mining第一部分，空場采礦的房柱法的分類OPEN STOPING空場采礦法 An open stope is an underground cavity from which the initial ore has been mined. Caving of the opening is prevented (at least tempora

2、rily) by support from the unmined ore or waste left in the stope,in the form of pillars,and the stope walls (also called ribs or abutments). In addition to this primary may also be required using rockbolts , reinforcing rods, split pipes ,or shotcrete to stabilize the rock surface immediately adjace

3、nt to the opening. The secondary reinforcement procedure does not preclude the method classified as open stoping. 露天采場臺階是開采了地下礦石后形成的地下洞室。通過塊礦或采場的支柱和 （也稱為肋或肩） 采場墻形式的廢料 的支持來（至少是暫時的） 預(yù)防放頂煤的開幕。除了這個，可能還需要使用錨桿，鋼筋棒，分流管，或噴漿，以穩(wěn)定緊鄰開幕的巖石表面。二次加固過程不排除歸類為開放式回采方法。 There are many forms of open-stope mining used to

4、extract the initial material from mine .Having once established that the mineral and waste rock are competent enough to use an open-stoping method ,and assuming that the reserve is not classified as gassy, the form which the method will take is primarily determined by the dip and thickness of the re

5、serve .How these two factors affect the selection of the open-stope mining is discussed in a later chapter . At this point it will suffice to say that the classification of the open-stope mining system which follows is based on whether dry , broken material flows by gravity or whether it must be mov

6、ed by non gravity methods where energy must be supplied to move the material. 這里有許多空場采礦法用于才出地下的礦石。一旦確立，礦物和廢石足以勝任使用開放式回采方法，并假設(shè)儲備不歸類為高瓦斯，該方法將采取的形式主要取決于浸和儲備的厚度。在后面一章，將討論了這兩個因素如何影響采場采礦法的選擇。在這一點上就足以說的露天采場采礦系統(tǒng)的分類，根據(jù)是否干燥，破碎的物料通過重力或是否流動，它必須由非重力能源必須提供移動材料的方法提出。Room-and Pillar-Mining房柱采礦法 Room-and-pillar mini

7、ng is an open-stoping method where mining progresses in a nearly horizontal or low angle direction by opening multiple stopes or rooms, leaving solid material to act as pillars to support the vertical load. Since the direction of excavation ( angle of dip ) is below that which would cause the dry ma

8、terial to flow by gravity to a draw point or gathering point, the material must be loaded in the room where it was extracted and transported to a point where it will flow, either by gravity or mechanical means, to a central gathering point to be taken out of the mine. This is an important aspect of

9、room-and-pillar mining which differentiates the system from other open-stope mining methods which rely heavily upon gravity to transport ore from where it was broken to a lower elevation, usually through a draw point .There are many variations of the method which go by a names in local districts: br

10、east stoping , breast-and-bench stoping, board-and-pillar, stall-and-pillar, and panel-and-pillar are all basically open-stope room-and-pillar mining.房柱采礦是空場采礦法挖掘凡進(jìn)步近水平或低角度方向通過打開多個采場或房間，離開固體材料采取行動，以支持垂直負(fù)載的支柱。自開挖方向（傾角）以下，這會導(dǎo)致干料流重力平局點或聚會點，礦石必須先儲存在礦房，在那里通過重力或機(jī)械手段被提取并運送到礦井旁的儲礦倉，然后要向提升井運輸。這是一個房柱采礦法區(qū)分從其它空

11、場采礦方法一個依據(jù)，依靠重力運輸?shù)V石到海拔較低的水平，通常這是繪制點制度的一個重要方面?？請霾傻V法有許多形式，如全面采礦法，留礦采礦法，分段采礦法，階段礦房法等都是空場采礦法的一種形式。In some instances detailed stope planning is almost nonexistent ;I .e., the operator simple follows the visual pay values , leaves pillars only where necessary ,and tries to locate them in the zones of lower

12、 value . This method of mining is as old as the beginning of underground mining itself ,dating back thousands of years .Early in the history of mining in this country ,the term ”gophering” was used to describe this method (peele,1941). The term is appropriate , for it brings to mind the exact result

13、s of this type of system-a random and irregular room-and-pillar mine.詳細(xì)的采場的規(guī)劃，在某些情況下幾乎是不存在的，在實際操作中一般按如下要求如下，只有在必要時保留支柱，并試圖找到礦石品味較低的區(qū)域作為礦柱。這種地下采礦方法本身就是很古老的，可以追溯到幾千年。早在這個國家的采礦歷史上，術(shù)語“gophering”被用來描述這種采礦方法（peele，1941）。這一詞是恰當(dāng)?shù)?，因為它使我想起這種類型系統(tǒng)隨機(jī)和不規(guī)則的房間和支柱礦確切的結(jié)果。 In other instances where the mineral values a

14、re consistent both in physical dimcnsions and quality, , the mine layout can be planned to the last detail , resulting in a uniform room-and-pillar mine. Coal , trona, gilsonite, potash, oil shale , salt, limestone ,and sandstone mines can usually follow such a system. Today, most metal mines using

15、a room-and-pillar operation try tomine as regular a pattern as possible but deviation in height , width, thickness, dip, and grade of the ore results in comparable deviation in the mine plan.在其他情況下，礦物的價值在物理性質(zhì)和質(zhì)量哪是一致的，礦山布局可以同時規(guī)劃的最后細(xì)節(jié)、 統(tǒng)一房柱結(jié)構(gòu)。煤炭、 天然堿、 瀝青、 鉀肥，油母頁巖、 鹽、 石灰?guī)r和砂巖地雷通常可以按照這樣的系統(tǒng)。今天，人們想把房柱采礦法作為

16、金屬礦開采的一種模式，但是礦體的垂直高度，寬度，厚度，傾角在實際礦山中變化很大。Variations of the Room-and-pillar System各式各樣的房主采礦系統(tǒng)It is necessary to briefly describe some of the many variations of the room-and-pillar system of mining, enabling the reader to fully explore the concepts and become familiar with the terminology used before g

17、oing on to the details of mine design.有必要簡要介紹一些房主采礦系統(tǒng)的多中變化，使讀者充分了解概念和熟悉的術(shù)語使用前，礦井設(shè)計細(xì)節(jié)。 Full-Face Slicing:If in the process of opening the rooms the total vertical extent of the mineral values of the particular seam or strata or extracted from the advance of one vertical face, the term used to describ

18、e this is full-face slicing .This face is also known as the “breast.”全斷面采礦法：如果在開放的礦房在垂直范圍內(nèi)有特殊煤層或巖層或從一個垂直面提前采出的礦產(chǎn)值的過程中，使用的術(shù)語來形容這種全斷面采礦。這個斷面也被稱為“工作面”。 There is no mineral of economic value intentionally left either in the floor or the roof (back) to be mined later .To be able to extract the fall-face

19、height in one pass, the mining equipment must obviously be designed to reach as high as the back . In an appalachian coal mine ,this may be all of 660.4 mm(26 in.) ; for a future oil shale property of mines where the mining face gets over 6.09 to 6.7 m (20 to 22 ft), the tendency is to divide the fa

20、ce into more than one pass. Over this height, it becomes difficult to properly see and remove loose rock from the back with a hand “mining bar”. Where the process of taking down loose rock has become mechanized , higher full-face mining can be safely practiced . Most eastern and mid western coal sea

21、ms and western uranium ,trona, and potash seams in the United States are easily reached in a single face; many limestone, lead,and zinc mines must resort, at least in part, to” multiple-slicing” to remove all the minerals of value.沒有經(jīng)濟(jì)價值的礦物或有意留在礦房頂部或(后留在頂部作為支撐，然后回采的。能夠提取的下降高度,在面對一個合格的采礦設(shè)備,顯然必須是旨在達(dá)到高

22、的背。 在一個阿巴拉契亞煤礦,這可能是所有的為660.4mm(26);為今后油頁巖的采礦面對得到超過6.09至6.7米(20至22英尺),目前的趨勢是,分成多個通行證。在這高度，從后面適當(dāng)?shù)乜春腿コ龑捤蓭r石用手“挖掘欄”變得難。在該進(jìn)程下采取的松散巖已成為機(jī)械化、可以安全地實行。提高全面采礦煤層最東部和中西部和西部的鈾礦，天然堿，鉀肥在美國的接縫很容易達(dá)到一個單一的面孔，許多石灰石，鉛，鋅礦山必須采取，至少部分，以“多片”值中刪除的所有礦物質(zhì)。 Multiple Slicing ( also known as multiple-pass mining): In many cases it is

23、 not practical to carry the full vertical height of mining horizon as a full face .The face is divided into parts known as breast , bench ,and/or brow . Ideally, if the operator knows the vertical extent of the mineralized, he will drill and blast the first pass at the top of the zone , thereby crea

24、ting the breast stope at the elevation where the permanent “back” (roof) will be . this allows easy access to remove any “l(fā)oose slabs of rock from the back while the rock is within easy reach and to secure the back with reinforcement bolts or pins if necessary. The process of scaling loose rock from

25、 either the roof ,pillars, brow, bench, or breast is in some districts referred to as “mining loose. 多個切片（又稱多通采礦）：在很多情況下，作為一個完整的工作面進(jìn)行充分挖掘地平線的垂直高度是不實際。工作面被分為礦房，臺階，和陡坡。理想情況下，如果操作員知道垂直的礦化程度、 他將鉆取高度第一個通過在區(qū)域的頂部，然后便于下一步的回采工作。這可以方便從后面去除任何“松散巖磚，而近在咫尺的巖石，并確保如果有必要的加固螺栓或銷回。從頂板，礦柱，坡頂，臺階還有巷道寬松的地方落下松散的巖石，這些地區(qū)被稱為“

26、采礦寬松區(qū)”。 Years ago , breast-and-bench stoping was practiced in a somewhat different fashion than it is today. The benches were very narrow , which allowed most of the fly rock from the breast to be blasted onto the floor of the stope , leaving very little rock lying on the benches.年前，前進(jìn)式開采和替補回采比現(xiàn)在有不同

27、的方式實行。臺階很窄，這使得大多數(shù)飛巖從工作面飛到采場的地板上，陡坡上留下很少的被炸開巖石。 Fig. I ( Anon. ,1972) illustrates a more typical stope for today trackless mining where again the breast the “heading” is carried at the top of the mineral zone but the benches are wide and , in effect, can serve as simultaneous levels of mining activit

28、y. The floor of each of a dipping ore body , or the lower benches may be advanced through the upper floors reflecting a thick, flat ore body. Working such an ore body in horizontal clices in a downward direction is known as “underhand stoping.”圖片一，更典型的采場說明了今天的無軌采礦再次進(jìn)行礦產(chǎn)區(qū)的頂部的“標(biāo)題”，但工作面寬，可起到作為采礦活動的水平工作

29、面的作用。底板傾斜礦體，或更低的工作面，可以提前通過反映了一個厚厚的，扁平礦體上部。工作這種礦物體在橫向在一個方向向下是稱為“地下回采。 Roof scaling and reinforcement ( rock bolting) would normally take place from the breast heading as it advances . Where the breast height does not reach the top of the mineralized zone ,an inverted bench can be carried in the roof

30、( Fig. 2 , Casteel, 1973) . Thus ,” taking down back” is a form of overhand stoping where horizontal slices are removed in an upward direction . In benching , the point where upper floor meets the vertical bench is called the “bluffline” or “bluff”; in taking down back , where the roof of the previo

31、us slice meets the vertical face the inverted bench, it is called a “ brow line “ or “brow.” Many times in irregularly shaped ore bodies ,it becomes necessary to leave the broken rock on stope floor so as to provide a means of gaining access to the height needed to drill and blast successive of the

32、back . The broken “back rock” can provide an excellent surge capacity in times of slack mine production once the top of the ore zone has been reached and the back made secure .But until that time is reached , it also represents inaccessible ore except for any excess ore that must be removed to make

33、room for more broken ore .頂板縮放和加固 (巖錨) 通常會發(fā)生打近路之時。在高度不能達(dá)到該最高的礦化區(qū)、一個倒轉(zhuǎn)臺階可以在頂板(圖5)。 2、卡斯蒂爾,1973年)。因此，下向回采是一種在形式上回采水平向上的方向的礦體。在臺階開采過程中，頂板與臺階接觸的點被稱為峭壁，在回采過程中，其回采的過程中的垂直于工作面的面，又叫陡坡線“或”陡坡“。許多情況下，對采不規(guī)則的礦體時留下一些礦石，來作為打鉆孔或時會采用的。破碎的返回巖可以提供良好的浪涌能力倍的可寬延時間礦山生產(chǎn)一旦達(dá)到礦帶的頂部與作出安全的背面。但直到那個時候，它還代表無法訪問礦石除外，任何多余的礦石，使礦石更破碎的

34、余地。 The mine in Fig .3(Anon.,19720) has been worked in the same fashion illustrated in Fig .1. There is some degree of uniformity in the size and spacing of pillars , but the uniformity often yields to the necessity of maintaining ore grade control . Consequently, the over all shape of the mineral z

35、one dictates the irregular shape of the existing mine . The large “bars were left either because of low-ground ore or because they were needed for ground stability. 在圖0.3（anon.，19720）礦井已在圖0.1所示的相同的方式工作。有某種程度的規(guī)模和支柱間距均勻性，但均勻性往往產(chǎn)生維護(hù)礦石品位控制的必要性。因此，現(xiàn)有礦山的不規(guī)則形狀決定所有的礦產(chǎn)區(qū)的形狀。因為地底上的礦石或地面穩(wěn)定的需要，因為他們留下的大“支柱”。 Othe

36、r Concepts of Room-and-Pillar Mines: There several concepts suggested in room-and-pillar mining which call for leaving long “bar pillars” on a regular basic for various reasons. This is common practice in softer and weaker materials such as coal, potash ,or shale ,but it has not been widely adopted

37、in the United States for use in hard rock mines .Such a system ,but designed for an entirely different reason, is shown in Fig. 4.This scheme might be needed where there is a need for the underground space to be utilized in an industrial development (Christiansen and Scott, 1975).This method of mini

38、ng creates a series of parallel rooms almost completely separated from each other by continuous “rib pillars” . Where large areas are mined for industrial stone ,and it is unlikely that one occupant could utilize the entire area, then this method has the advantage of creating rooms without the neces

39、sity of constructing partitions after mining .房柱采礦法的其他概念：由于人們習(xí)慣的原因，這里有許多被人們長時間不用的房柱法。在柔軟和較弱的材料，如煤炭，鉀肥，或頁巖，這是常見的做法，但還沒有在美國被廣泛采用硬巖礦山使用。這樣一個系統(tǒng)，但設(shè)計一個完全不同的原因，顯示圖4。這項計劃，可能是要在地下空間利用 （克里斯蒂安森和斯科特，1975年） 工業(yè)發(fā)展中應(yīng)用。這種方法的采礦造成一系列平行的客房幾乎完全分開的每個其他不斷肋支柱。大面積的工業(yè)石材開采，和一個可以利用整個地區(qū)，這是不可能的，那么這種方法具有的優(yōu)勢，就是沒有開采后的分區(qū)建設(shè)的必要性。Still

40、 another mining plan , shown in Fig.5 and known as “stope-and-pillar,” was used at Elliot Lake(Hedley,1972 ). Here ,the panels were laid out in a series of 30.48- m( 100-ft) stopes and 30.48- m (100-ft) pillars. There pillars were left by mining the stopes out 15.24 m (50-ft) on each side of a prede

41、velopment inclined drift.還有開采方案，如圖5所示，被稱為“空場采礦法，在埃利奧特湖（赫德利，1972年）”。在這里，面板，奠定了在一系列30.48米（100英尺）采場和30.48米（100英尺）的支柱。離開挖掘出15.24米（50英尺）的采場的前期開發(fā)斜巷兩側(cè)有柱子。Finally, we come to the most common of all room-and-pillar mining systems and that which is basic to most coal mining in the United States .There are man

42、y different development plans ysed throughout the county, different primarily in pillar size and shape ,entry size, shape and number of parallel entries that must be developed simultaneously through the mine. Fig. 6 and 7 are typical (paulick,1963 ).They show not only different schemes of seam devel

43、opment , but also a difference in the method used for mining the pillars while retreating from the mining area.終于，我們來到最常見的所有房柱采礦系統(tǒng)，這是在美國的大部分煤炭基本開采方法。有許多不同的發(fā)展計劃全縣主要支柱的大小和形狀的不同，項目的大小，形狀和平行條目的數(shù)量必須同時通過礦山開發(fā)。圖6日和7日是典型的（paulick，1963）。它們顯示不同方案的煤層發(fā)展，不僅用于同時退出采區(qū)開采支柱的方法的不同。Structural Character of Deposits Minab

44、le by Room-and-Pillar房柱采礦法的結(jié)構(gòu)特征If most mining engineers were asked to describe ore bodies applicable to room-and-pillar mining ,there first response would probably be to describe them as any ore body which is large, flat , and in competent rock . Certainly , there are some of the ideal conditions wh

45、ich make room-and-pillar mining relatively efficient; however ,they are by no means the limiting criteria from which room-and-pillar mining should be selected.大多數(shù)采礦工程師如果被要求描述那些礦體適用房柱開采，那他們的第一反應(yīng)可能會是任何大礦體，礦體傾角小，和巖石穩(wěn)固來說。當(dāng)然，有一些理想的條件下，相對高效的房和柱采礦，他們絕不是限制標(biāo)準(zhǔn)應(yīng)選擇從哪個房柱采礦。 The discussion of the physical propert

46、ies of ore and waste given subsequently is intended to make clear to the reader why room-and-pillar mining has such a broad application .Any criteria considered in determining the type of mining method used must ,in the final analysis , include all of the following factors: safety ; optimal mineral

47、recovery; a mining environment consistent with current social , political, and legal requirements; and an operation which returns the highest economic gain.礦石和廢物在以后提出的物理性能的討論的目的是明確的讀者，為什么房間支柱挖掘具有廣泛的應(yīng)用。在確定采礦使用的方法的種類考慮的所有標(biāo)準(zhǔn)必須，在最后的分析，包括所有跟隨的因素： 安全; 優(yōu)選的礦物補救; 采礦環(huán)境一致與當(dāng)前社會，政治和法律規(guī)定; 并且退回最高的經(jīng)濟(jì)獲取的操作。 Strength

48、 of Rock Mass: While the subject of rock mechanics is covered in great detail in section 7 of this text, some aspects of will be briefly mentioned here as the subject relates to open-stope mining .巖體的強度，而覆蓋在該文本第7條很詳細(xì)的巖石力學(xué)問題，某些方面將簡要地提到為主題涉及到露天采場采礦。 The earth composition consists of a number of materi

49、als , each having its own physical properties .There materials are arranged in the earth crust in various forms: solid or broken mass, homogeneous or nonhomgeneous , rock mass subjected to tectonic stress or rock free from tectonic stress, etc .However , as rock is normally encountered in mining , i

50、t is equilibrium with the other forces of nature . The mine engineer contemplating the design of an open-stope system must assess the general magnitude of these forces , as well as the strength of the mass of material that will be exposed by the opening . Accordingly , he will design his extraction

51、opening in such a way as to preserve the structure of the opening long enough to successfully complete the extraction . This , by our original description of an open stope , as well as mine practice and mining regulations , may or may not include roof and pillar reinforcement . Also , it may or may

52、not include yielding rock structures that are gradually failing at a carefully monitored rate . In fact , when one looks at the broad spectrum of materials that are commonly mined by room-and-pillar methods ,from all types of “host” rocks ranging in strength of 275.7 to 344.7MPa (40,000 to 50,000 ps

53、i )down to 27.5 to 34.4MPa (4,000 to 5,000) , and at mining depths varying from around 15 m(50 ft) down to over 914m(3000ft ) ,one begins to realize that with today methods of reinforcing the rock mass-or by using the design tools of rock mechanics in developing such systems as the pressure arch pan

54、el and pillar systems , or the use of a yielding structure or mechanical which at a predetermined rate eventually fail-it seems that nearly any rock that will sustain a development opening without immediate major support could probably be mined by some form of room-and-pillar mining .This is not to

55、say that it would always be wise to do so indeed, it becomes a matter of sufficient total recovery of the mineral as well as selecting the method which will yield the greatest financial gain . Yet , there is sufficient evidence of the use of room-and-pillar mining methods in fairly weak materials th

56、at leads one to conclude that the rock need not be entirely competent .Examples of this are seen in many of the salt mines , the sandstone mining of New Mexico and Wyoming uranium districts , some of the brecciated riff zone structures of the New Lead Belt in Missouri , the mining at depth of the No

57、nesuch shale at White Pine , and the potash beds of Saskatchewan . Later in this section , methods of reinforcing rock and details of room-and-pillar layouts as well as the percent of allowable extraction of the reserve , will be covered .地球成分組成的材料的數(shù)量，每個有它自己的物理性質(zhì)，化學(xué)性質(zhì)的材料，在地殼中的各種形式的安排：固體或破損的程度，同質(zhì)化或者非

58、齊次，巖體受構(gòu)造應(yīng)力或巖石構(gòu)造應(yīng)力等。然而，巖石通常是自然的挖掘中遇到時，是自然的與其他勢力平衡。正在考慮的穩(wěn)固性系統(tǒng)設(shè)計的礦山工程師必須評估這些力量的一般程度，以及質(zhì)量將公開的開放的材料的強度。因此,他將設(shè)計其開采開放的方式,保持開放的結(jié)構(gòu)很長時間,可以成功地完成的開采。這由我們原始的描述的露天采場臺階，以及礦山開采的實踐與法規(guī)，可能包含或不包含房柱加固。此外，它可能包含或不包含高產(chǎn)嚴(yán)密監(jiān)視的速度逐漸發(fā)生故障的巖石結(jié)構(gòu)。事實上，當(dāng)一個著眼于通常由房間和支柱方法開采275.7實力344.7mpa（40,000至50,000 PSI）下降到27.5不等的“主機(jī)”巖石類型，材料的廣譜34.4mpa

59、（40005000），開采深度約15米（50英尺）從不同超過914米（3000英尺），人們開始認(rèn)識到與今天的方法，加強質(zhì)量或使用的設(shè)計工具的巖石巖石力學(xué)發(fā)展等系統(tǒng)的壓力拱面板和支柱系統(tǒng)，或使用高產(chǎn)制結(jié)構(gòu)或機(jī)械的預(yù)定率在最終失敗似乎，幾乎任何巖石將維持不立即主要支持的開發(fā)開放，很可能一些房間和支柱采礦的形式進(jìn)行開采。這并不是說，它總是這樣做，確實是明智的，它變成了足夠的礦物質(zhì)，以及選擇的方法，這將產(chǎn)生最大的經(jīng)濟(jì)收益的總回收率的問題。然而，有足夠的證據(jù)房柱采礦方法在相當(dāng)弱的巖石中使用，巖石不必完全承受。這樣的例子在許多鹽礦，新墨西哥和懷俄明州的鈾區(qū)，角礫即興在密蘇里州的新的領(lǐng)導(dǎo)帶區(qū)結(jié)構(gòu)的砂巖開采，

60、在開采深度的典范頁巖白松，薩斯喀徹溫省的鉀肥床。稍后在本節(jié)中的方法加強巖石和細(xì)節(jié)的房間和支柱的百分比的設(shè)計以及允許提取的準(zhǔn)備金,將涵蓋。 Effect of Size , Shape ,and Thickness of Mass: According to an industry study (Dravo , 1974), 15 of the 23 largest noncoal mines in the United States use room-and-pillar mining . Obviously ,it is adaptable to very large mineral res

61、erves. One has the means of opening many production areas by merely extending the lateral extent of the mine without the necessity of deepening the shaft and rebuilding the ore handing and hoising systems in the process .大小，形狀，厚度的影響：根據(jù)行業(yè)研究（dravo，1974年），在美國使用房柱式開采的23個最大的非煤礦山15。顯然，這是適應(yīng)非常大的礦產(chǎn)儲量。一個只是延長沒

62、有深化軸的必要性煤礦的橫向范圍和重建的礦石移交過程中提升系統(tǒng)開放許多生產(chǎn)領(lǐng)域的手段。While many of the mines use room-and-pillar methods , a large percentage of very small mines also use them .In fact , while the size of the mass to be mined does affect the size of the operating mine , it has no effect on whether or not it is advisable to us

63、e room-and-pillar mining . Many a small room-and-pillar zinc mine has been operated in the Illinois-Wisconsin area ,as well as in the old Tri-State district of Missouri , Oklahoma , and Kansas. Yet ,the same basic system is operating at White Pine where as much as 20 407.5t/d(22,500 stpd0has been pr

64、oduced .而許多礦山使用房柱采礦的方法，很大比例的一個非常小的礦山還可以使用他們。事實上，同時被開采量的大小不影響經(jīng)營煤礦的大小，它有沒有效果，不論它是建議使用房間和支柱采礦。許多小房柱鉛鋅礦已在伊利諾伊州，威斯康星州的礦山使用，以及在老的三州地區(qū)的密蘇里州，俄克拉何馬州，州和堪薩斯州。然而，相同的基本制度，經(jīng)營白松多達(dá)20407.5噸/ D（22,500 stpd0has制作）。If the mineral to be mined is dipping steeply enough that the material will flow by gravity , and at the

65、same time is very thick or very thin (narrow) , the reserve is not one which should be mined by room-and-pillar methods . Other than these limitations related to the shape of the deposit and where single entries can be used , room-and-pillar mining is flexible enough in both the horizontal and verti

66、cal directions too follow the outlines of all other mineral reserves . To the extent that the extracted material can be loaded and moved from where it is broken by mechanical equipment and where competent pillars can be formed (or reinforced ), the shape of the mineral body to be mined will not preclude the selection of room-and-pillar m