GENERAL45973 - Laserfiche WebLink

Home Browse Search

~f :s ~f -b s e m r- as :t FIG. 5 added to boost the intake when the longwall panel is nearly retreated. A 270-kg (600-Ib) capacity rack-and- pinion elevatoc was installed in the 229-m- (750-ft-) deep shaft. The intake from the bleeder area to the longwall allowed for a separate and distinct intake escapeway from the longwall face. The blowing fan was installed to maintain the air direction attd pressure from the bleeder area to the outby end of the long longwall panels. When the 6,700-m (22,000-Ft) panels were proposed, the longest existing longwall panel was about 3,600 m (11,800 ft). This existing length became a measuring stick from which [he regulatory agencies would deter- mine the criteria for a safe length of escapeway out of a mining section. These criteria led to the internal devel- opment of several escapeway plans for the firs[ two gateroads in the EMD, the longwall section and subse- quent gateroad development sections. The firs[ two gateroads in [he EMD were developed with barricade chambers and 200-mm- (8-in.-) diam cased holes to the surface at the midlength of the gateroad. The bar- ricade chambers were designed to be self sustaining for an entire crew. And they had access [o direct com- munication to the surface by the cased holes. A 1.22-m- (4-ft-)diam shaft was developed a[ the midpoint of the mouth of both sections as a second- ary means of escape vs. traveling the entire 2,287 m (7,500 ft) of 15% grade main entries to the surface. The longwall section was pro- vided with two separate intake escapeways to the surface by the outby haulage road (No. 2 entry) and the inby road (No. 3 entry) to the bleeder intake shaft. After connecting the first two gateroads. the subsequent gateroads were proposed [o contain across- panel borehole of 1.22 m (4 ft). There, the continuous miner section FIG. 6 would need to travel only to the midpoint of the panel development and cross over to the longwall intake in No. 3 entry intake from the bleeder area. The cross entry borehole concept was tabled because the entire three- en[ry, continuous-miner section was developed across the panels (Fig. 8) to expedite [he gateroad develop- ment. Testing various tailgate support was another impor- tant criteria in developing [he ventilation requirements. These supports needed [o provide proper ground control while minimizing [he airway resistance. The dominant method of tailgate support in the western mining district was three rows of concrete donut cribs on 3-m (10-ft) centers. The support technique provided a stable tailgate for the longwall. However, the length of [he panel would double in the EMD. So the crib scenario increased the resistance vs. an open entry by about 40%. The proposed method of support for the EMD was using roof trusses and a single row of concrete cribs. The last three panels of the western mining district used vari- ous types of support to decrease airway resistance, in- cluding [he proposed roof truss system. All were MINING ENGINEERING ~ DECEMBER 1998 25 A roofbolter is used to install primary support during continuoua mining advance at Twenrymile. Western mining district with Fish Creek alluvial valley floor. Power line foundation area relative to the longwall panel, for testing subsidence.