The method has important advantages in coping with nonlinearity and complex geometry. Post roomandpillar mining or postpillar mining is a combination of roomand pillar and cutandfill stoping. Placer mining is used to sift out valuable metals from sediments in river channels, beach sands, or other environments. In this system a series of parallel drifts are driven, with connections made between these drifts at regular intervals.
Appendix q finite element analysis of barrier pillar. Applicability of bord and pillar method the bord and pillar method is adopted for working. Changes in the seam thickness associated with the bending, shrinkagepinching out and also splitting of the seam accompanied often with tectonic structures represent points. Mining of coal pillars using the drilling method 244 b. Longwall mining is also scheduled to be installed at other large underground operations in the west. Most popular underground mining method in us for noncoal operations can be adapted to dipping seams pitch mining or very thick seams bench mining usually, conventional production cycle is used. The tcut mining method is basically a partial pillar extraction method. Mining can be done in two ways, underground and open cast. Conventional bord and pillar mining in thick seams is associated with very low percentage of extraction around 30% in a panel even. The remainder of the coal is won by a retreating system, the cover being. The rest of the coal is left in place in the form of pillars that hold up the roof and prevent.
Then the outer pillars were mined, leaving the roof to collapse in a controlled way as miners retreated to the exit. The pillar m x m created by the bord and pillar development is being stoped only the ug2 reef out for 2 m from the roadways on all sides, to leave an effective pillar of 9 m x 9 m. Miners first extracted coal along roadways or bords, while the coal in between the bords acted as pillars holding up the roof. Bord and pillar mining has some favourable promises such as improving labour difficulties, lowering operating costs and providing safer working conditions. In development, pillars are formed by driving a network of galleries, of which one set is generally parallel to the dip and the other set is parallel to the strike cutting the former at right angles. It is employed where geomining conditions are complex. These guidelines are to a large extent empirically derived and based on case histories of pillar performance from a number of mines. Three sets of pillar dimensions were used for each pillar width to pillar height ratio, this was done to determine whether different room and pillar dimensions for each pillar width to pillar height ratio resulted in different convergence rates. Applicability of bord and pillar mining method following points should be considered for bp mining gradient of the seam. Wilsons continuous pillar desing approach wilsons 7 method of pillar desing is applicable to soft rock at great depth and is based on the following main assumptions. It is among the safest and one of the most ecologicallyfriendly approaches to mining coal today, creating a nonsubsidence environment no movement of land and maintaining clean water standards. Unesco eolss sample chapters civil engineering vol. The second working is similar in principle to top slicing.
When the distance between connecting drifts is the same as that between the parallel drifts, then a. Bord and pillar mining method comprises two phases i. Bord and pillar method of mining is one of the oldest methods. In the shortwall mining method, the layout is similar to the longwall method except that the block of coal is not more than 100 metres wide. Underground mining with a crown pillar no planned impact on lac du sauvage. Yamatomi encyclopedia of life support systems eolss figure 2. Room and pillar mining is a nonsubsidence plan for a mine, preserving the precious farmland above. Pillar extraction using continuous miners introduction.
Finite element analysis of mining involves computation of stress, strain, and displacement fields induced by. Doublefacelongwall mining with blasting, used in the then leningrad oil shale minefields at the end of the 1970s 2, served as the background of the new rap mining method with cm see fig. Furthermore, the slices are as much as three metres thick and are taken by a continuous miner. Bordandpillar definition of bordandpillar by merriam. The deliberations of the various breakaway groups, and subsequent analysis of the presentations by the authors, are. Large roomand pillar stone mining fundamentals the value per ton of ore for large roomand pillar stone mines is typically low, therefore productivity must be high. Now that longwall equipment has been developed to a stage where it is able to cope with most conditions satisfactorily, longwall mining is the most widely used method of secondary extraction. Mining methods generally speaking, there are two main methods of extracting coal from a seam. According to stress balance theory, destressing caused by mining in the caved zone must be. For these reasons, much of this chapter compares longwall mining with the dominant underground mining technology in the westroomandpillar mining with continuous miners. The key to the successful bord and pillar mining is selecting the optimum pillar size. Soft rock mining refers to excavation of softer minerals such as. Surface mines are typically used for more shallow and less valuable deposits. With this method, ore is recovered in horizontal slices starting from the bottom and advancing upward.
Analysis showed that the new method gives the greatest extraction factor up to 90%. Both methods are well suited to extracting the relatively flat coalbeds or coal seams typical of. Method of underground mining by pillar extraction bowen. Bord and pillar method handouts free download as pdf file. When retreat mining is completed to the mouth of the panel, the mined panel is abandoned. Other articles where roomandpillar mining is discussed. Pillar mining article about pillar mining by the free. The open pit approach was the subject of a separate study by others in 2010.
Underground hard rock mining refers to various underground mining techniques used to excavate hard minerals, usually those containing metals such as ore containing gold, silver, iron, copper, zinc, nickel, tin and lead, but also involves using the same techniques for excavating ores of gems such as diamonds or rubies. Mining processes involve prospecting for ore bodies, analysis of the profit potential of a proposed mine, extraction of the. One of such methods is the bord and pillar method of mining. The success of mechanized bord and pillar mining in narrow tabular steep dipping orebodies. This method creates the required, higher extraction percentage and higher run of. A system of mining in which the distinguishing feature is the winning of less than 50% coal on the first working. The room and pillar method is often used to mine smaller coal blocks or thin seams, and seam recovery ranges from 35% to 70%, with higher seam recovery rates applicable where retreat mining is combined with room and pillar mining. Underground mining with a crown pillar is the base case approach assessed in this study report. Okubo encyclopedia of life support systems eolss surface mining methods and equipment j.
Mining will be rateindependent can mine at a high rate and geologyindependent. It is more an extension of the development work than mining. This diagram shows the traditional method of bord and pillar mining. Open pit followed by underground mining may be considered at a later stage of study. Examine the criteria for establishing the small span small.
Introduction longwall is an underground mining method which has a high rate of production capacity and mechanization ability. Toward pillar design to prevent collapse of roomand. Other articles where shortwall method is discussed. A method of sublevel caving and pillar and top coal extraction for mining thick coal seams includes the advance mining of rooms and crosscuts along the bottom of a seam to a height of about eight feet, and the retreat mining of the top coal from the rooms, crosscuts and portions of the pillars remaining from formation of the rooms and crosscuts. This method is sometimes called roomand pillar mining. Kutec ag salt technologies sondershausen backfilling and pillar remining in potash industry c.
Average pillar stress is considerably lower for bord and pillar than for the other methods with comparable extraction ratios see table 3. Types of underground mining underground mining for coal is conducted by either room and pillar mining or longwall mining. Open pit mining mining methods 5 open pit mines are used to exploit low grade, shallow ore bodies. There are still reservations regarding pillar foundation failure and a new pillar design method is proposed. This can be better understand with the help of follwing fig. However, there are still mines and occasions where longwall mining is not suitable e. Design of bord and pillar method in coal mines slideshare. The mineralization was processed at the copper rand mine in chibougamau and 40,000 oz of au was recovered. Bord and pillar methodhandouts coal mining explosion. This method is sometimes called roomandpillar mining. The first, and most generally used in the earlier years of coal mining, was the room or bord and pillar method of extraction and the second is the longwall method, which was used in the collieries of cape breton most recently. Chapter 2 bord and pillar design in coal mining wiredspace. Calculating the size, shape, and position of pillars is a complicated procedure, and.
Chain pillar, longwall mining, numerical methods, pillar design, pillar optimization 1. In 1994 to 1995, msv resources mined 118,356 tonnes grading 10. Bordandpillar definition is of or relating to a system of coal mining in which tunnels are driven in a checkerboard pattern having massive square pillars between them which are gradually cut away as the work proceeds. Underground mines are more expensive and are often used to reach deeper deposits. The mining rate is greater than 20,000 tonnes per day tpd but is usually much greater. The method is popular, especially in engineering, because of a relative ease of implementation compared with traditional finite difference methods. Coal is removed from the coal faces initially by developing a set of galleries leaving pillars in between to support the roof. The name varied depending upon the part of the country the mining took place, however the method was basically the same. Room and pillar variant of breast stoping, is a mining system in which the mined material is extracted across a horizontal plane, creating horizontal arrays of rooms and pillars.
In mining practices, the pillar width to pillar height ratios are designed to be 1. Analysis showed that new mining method gives greatest extraction factor up to 90%. In room and pillar mining, approximately 50 percent of the coal is removed, using a continuous miner, from areas known as rooms. As a background for new roomandpillar mining method with continuous miner was taking doublefacelongwall mining with blasting, used in exleningrad oil shale minefields at the end of the 1970s nikitin 2001. The two industries ranked together as the primary or basic industries of early civilization.
All the advantages of bordandpillar mining make this method sound like the ultimate cost effective and efficient mining method, but there are major restrictions to its application, e. Large reserve and uniform deposit are mined by longwall mining a bulk. Hardrock room and pillar mining best practice industry. Sometimes both these phases proceeds simultaneously. Pdf practical importance of the room and pillars method different.