GENERAL45973 - Laserfiche WebLink

Home Browse Search

FIG. 9 It e ~n ~n ~0 is ;i Gateroad conveyor profile. Conveyor system design was the most challenging part of the long panel longwall design at Twentymile. HEAD 6000 ~2~ ssao 9 RIGHT PROFILE °o p 0 0 _........o _ 0 0 0 manufacturers were chosen to provide samples for test- ing. Both belting designs passed the tests performed on dynamic testing equipment in Germany. So the decision became a mattzr of economics. The ability to provide a 3.8-MPa (2,000-psi width) belt then led to the design requirements for the equip- ment that would kzep the tension constant in [he system and limit the number of trippec drive installations. TCC had several years of expzrience with tripper drive instal- lations- in the western mining district and felt comfort- able continuing that in the EMD. The major difference between the western and east- ern mining districts was the use of power trippers in the west and the combination of powering and braking/re- generative trippers in the east. The control systems and software necessary to allow the various drives in the long panel belt to keep [he tension constant was performed between TCC and a leading conveyor manufacturer. The conveyor would also require a tail braking sys- tem as part of the total package. This tail brake was in- corporated into the longwall tailpiece after hours of engineering collaboration between [he mine and the conveyor manufacturer. The system has worked well throughout [he first two long panels of the district, al- though alignment issues in the first panel required some redesign. Another unique portion of the total conveyor sys- tem is the collapsible structure used for 76 m (250 ft) between the longwall stageloader and the rigid structure installed on development. This system has provided im- proved productivity because [he longwall crews do no[ have to pull belt structure on retreat. There were many interrelated conveyance issues to provide a successful single-flight conveyor system that would handle 4.5 k[/h (5,000 stph) and 6,700 m (22,000 ft) and be engineered in the required timeline. Several are mentioned here but there were other issues that needed to be either engineered or solved by the mine operations personnel. Longwell equipment design The key element in the equipment design for [he longwall in long panels is the 5.4 raw Mt (6 million raw st) of coal mined between longwall moves. TCC began experimenting with equipment life by skipping rebuilds between panels on major components, such as ranging :arms and armored face conveyor gear boxes. The ab- ;ence of data in the industry pertaining to long panels :Ind high tonnage before rebuild did not help in the de- cision making. The longwall has mined nearly two long panels to date and the results on equipment life vary due 6°~ TAIL 0 0 + + o u i n to [hz variations in mining conditions. The longwall equipment had to meet the goal of 4.5 kt/h (x.000 stph) capacity. And it had to fit into the seam requirements from 2.13- to 2.74-m (7- to 9-ft) mining height. The shearer speed is capable of 45 m/min (150 fpm) to provide [he 4.5 kt/h (~,D00 stph) capacity in the unique cutting system at TCC. The shearer typically cuts a half web in each direction to control the immediate roof and face bursting. This cutting method lends itself to high shearer speeds because the required cutting force is lim- ited. Thz ergonomics of the longwall shields was scruti- nized because the operators would be traveling an average of 10 km (6.2 miles). per 10-hour shift. The shield capacity and ergonomics design had [o meet the varying geologic paramzters of the EMD and the re- quirements of walkway and head clearance. This was primarily accomplished with large-diameter leg shields. These enabled the shields to provide the setting forces required and adequate walkway clearance. Conclusion Several of the project requirements described here provide a sense of scope for the amount of work and is- sues that needed to be resolved in designing long long- wall panels a[ TCC. A key concept a[ [he beginning of the EMD project was increasing the longwall: continu- ous miner ratio and reducing mine costs. These criteria coupled with the goal of 4.5 kt/h (5,000 stph) led to many of the design considerations used in the long panels. Another important note is that all the issues de- scribed were coordinated while still operating a longwall mine at 2.7 [0 4.5 clean Mt/a (3 [0 5 million clean stpy). Many of the subprojects described had to be worked into the existing mine operations for testing and timely data collection before the EMD would be developed. After the original project engineering was com- pleted, the actual length of panels in [he EMD was 5.488 m (18.000 ft) due to development timing from geologic conditions. This shorter length does not take away from all the issues and engineering design listed here. They have resulted in world record production including 919 kt (1 million clean st) in Lune 1997. The developments of long panels for longwall min- ing at TCC was completed through the efforts of several operations, administrative and engineering personnel at Cyprus Amax Coal, along with many manufacturers and vendors. The long panel project has contributed many new underground longwall mining concepts and prac- tices that have become new standards throughout the world. It has also removed barriers that might otherwise not have bezn tested in the coal mining industry. ^ MINING ENGINEERING ^ DECEMBER 7998 27