longwall mining dog leg; Longwall :: Home. ... The main difference between shortwall and longwall mining is that in shortwall mining, the widths of the panel blocks are less than 600 ft (182 m) while in longwall mining, the width ranges from 600 to 1200 ft (182 - 305 m) while the lengths range between 3,000 and 14,600 ft (911 - 4450 m). ...

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In the longwall system the ore body is divided into rectangular panels or blocks. In each panel two or more parallel drifts (for ventilation and ore transport) are driven along the opposite long sides to provide access, and at the end of the…. The other principal method of modern mining, longwall mining, had been introduced as early as the ...

Longwall mining is the most common of the underground coal mining methods used in Australia. It suits sites where coal seams are thicker, wide and have a consistent coal profile with gentle dip. In longwall mining, large rectangular sections of coal are identified and removed in one continuous operation (Trueman et al. 2009). Basically, …

Overview. In the method of secondary extraction known as longwall mining a relatively long mining face (typically in the range 100 to 300m but may be longer) is created by …

Maintaining adequate load capacity is essential for proper support of the roof and the safe operation of the longwall [70] [71] [72]. Powered roof support, where 1-canopy, 2-hydraulic prop, 3 ...

Longwall mining is one of the two most popular mining methods of underground coal mining, the other being room and pillar (or bord-and-pillar) mining. The basic principles of longwall mining involves a coal bed being selected and blocked out into a panel ( Fig. 1 ) averaging nearly 100–350 m in width, 1–4 km in length, and about 2–4 …

Although fully automated, plow longwall never caught on in the U.S. and U.S. has little contribution in the development of automated plow longwall mining, and due to …

Longwall Mining - SlideShare. Face monitoring– Strata monitoring • Leg Pressures • Leg Closures • Face Convergence PRESSURE SURVEY Continuous Pressure Recorder in Mid Face of a Longwall Panel 40 Yield Pressure 35 30 PRESSURE (M pa) 25 Setting Pressure 20 15 33.6 39.3 56.2 74.1 95.4 111 119 141 163 180 198 220 237 259

Shield leg pressure data from all shields and shearer location with time stamp from a mechanized longwall face are monitored and recorded in a surface computer. These data contain random noise due to power failure, leakage of legs, bad sensor reading and other maintenance or geo-mechanical problems. An algorithm is developed to detect mining …

Energy. Longwall mining is a form of underground coal mining where a long wall of coal is mined in a single slice (typically 1-2 m thick). The longwall "panel" (the block of coal that is being mined) is typically 3-4 km long and 250-400 m wide. Longwall mining produced 176 million tons of coal in 2007, about 15 percent of total U.S. production.

The move from 4 leg chock shields to 2 leg shields has had the benefit of minimising the number of legs that have to be maintained on a longwall face. However, …

Mine Subsidence Engineering Consultants Level 1 / 228 Victoria Avenue – Chatswood – NSW 2067 PO Box 3047 – Willoughby North – NSW 2068 Tel. (02) 9413 3777 Fax. (02) 9413 3822 Email: enquiries@minesubsidence. Revision A …

The hydraulic powered supports have been employed in U. S. longwall mining for the past two decades. Yet the sciences of roof control at the powered supported faces remain largely unknown. In order to improve longwall roof control and increase production, a series of questions in longwall roof control should be studied and answered: what is the basic …

Longwall coal mining process. Longwall coal mining is a full extraction underground mining method that involves the removal of coal in large blocks or panels using a mechanised shearer. The coal panel is typically 200–450 m wide and can be up to five kilometres in length. The mechanical shearer is mounted on a shearer pan and rails …

Face Alignment and Creep. Face alignment, creep and face angle (relative position between main gate and tail gate location, which controls creep) are usually corrected by making straightening cuts or fly cuts working to a string line and carried out at the discretion of the longwall Supervisor. The decision is generally based on experience of ...

1. The longwall panel is 1000 ft wide and 10,000 ft long. 2. The coal seam has an average thickness of 6 ft. 3. The coal block to be degassed is 1300 ft by 10,000 ft, assuming that the width of chain pillars is 300 ft. 4. The cost of contract drilling for the in-mine horizontal drilling is $50/ft. 5.

Longwall mining is a primary method for extracting coal from underground mines. As shown in Figure 1, three kinds of mining equipment used in the longwall face are a shearer, an armored face conveyor (AFC), and a roof support system.The shearer moves back and forth along a rail connected to the AFC, while the roof support system …

This video provides a basic description of the longwall mining method for extracting coal underground. It includes an explanation of the different products/key components of a …

The shortest of its 11 longwall faces is now 1,100 ft, with the exception of the company's Buchanan mine in ia, which is running 700 ft due to geological conditions. All of the CONSOL Energy longwall faces are high-voltage state-of-the-art units with electronic controls and controlled start technology (CST) drives.

LONGWALL MINING. introduction; longwall or not? planning; block size; equipment selection. armoured face conveyors; face supports; shearers; top coal caving; automation; cutting methods; avoiding & correcting …

LONGWALL mining EQUIPMENT SELECTION a) Armoured Face Conveyors (AFCs) ... A typical modern 2 leg support shown with its AFC pan section in place. ... While dog bones have had improvements in …

The legs of a chock shield support are either vertical or inclined but the majority of chock shields have inclined legs as this provides better support pressure to the canopy. The main features of chock shield supports are: The four legs act directly onto the canopy. The yield load is constant throughout the height range. The top canopy can …

More U.S. longwall operators embrace automation technology to improve horizon control By Steve Fiscor, Editor-in-Chief America's longwall mines produced 133.1 million tons in 2023, which was down 3.1% from 137.3 million tons in 2022. Much of the decrease can be attributed to the loss of production from two mines that are no longer …

Longwall mining in coal seams is an underground mining technique where a tabular block (longwall panel) of coal with a typical length of 1.5–3 km, typical width of 250–300 m and typical height of 3–4.5 m is extracted. Two pairs of roadways are first driven around the outside of the panel within the coal seam for access.

Abstract. The designs of single- and double-telescopic hydraulic legs are analyzed, and the stand tests are carried out under dynamic loading in conformity with the requirements of European standards. The choice of facilities ensuring the reliable operation of powered support under different loading conditions is substantiated.

Longwall mining is a method of carving "hallways" into underground coal seams and then mining long corridors of coal adjacent to the hallway. As the coal is mined and carried away via conveyer belt to the surface, the ceiling above the mined coal collapses. This can cause subsidence on the surface. Erin Pfeil-McCullough, a graduate …

Advancing and Retreating Longwalls. Longwalls can be operated in two ways, referred to as "advancing" or "retreating" faces or frequently simply as advance or retreat longwalls. Advancing Longwalls. Retreating Longwalls. Comparison …

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In the Longwall mining method, the coal face is being supported with two-legged or four-legged shield supports which improve better roof control between the face and canopy tip. The development of ...

Longwall mining is a form of coal mining underground. In the longwall method, a long wall of coal is found and mined in a single slice between 50 cm and 6 m thick. Longwall panels (the coal seam being mined) tend to be between 3 km and 4 km long but can extend as far as 7.5 km. They are usually between 250 m and 400 m in width.

The paper describes a case study of the safety hydraulic system damage in the working of a longwall in a Polish coal mine. The safety elements are a component of the powered roof supports which ...

A novel no-pillar longwall mining method (NPLM) by roof cutting technology (RCT) was proposed in China, it can mitigate mining damage by increasing the volume …

This paper presents a critical review of the various approaches for the selection of the optimum length of longwall face considering ground control and cost parameters. Various factors affecting the efficacy of roof control and their impact on the productivity of a mechanized longwall face have been identified. The outcome of the …

In principle, longwall mining is quite simple a coalbed is blocked out into a panel a veraging. nearly 800 f t (244m) in width, 7000 feet (2100 m) in length, and 7 feet (2.1m) in height, by ...

Back-analyses have been carried out at 5 Australian longwall mine sites (10 longwall panels in total) to determine threshold values of critical leg pressure and convergence load cycle features ...

To propose a support stiffness based method for improving the stability of coal wall, static stiffness of the support and fracture development of the coal wall are monitored during retraction period of a panel in the second coal mine of Zhaogu coalfield. It is revealed that the range of support stiffness falls between 50 and 450 MN/m. In face …

Throughout the history of longwall mining, the design of the roof support system has been critical to the success of the mining operation. Early forms of longwall mining used wood props for face support and packwalls made from roof and floor rock to control caving of the imme­ diate roof (I).2 These systems were replaced by powered