Bisbee daily review., 1916-07-23

and thence into the chutes.
 l While the last of the upper St-.a. <
 CTS are being placed in position, a se--
 ond slice is started on the GOcc Lc-
 low, by taking a sit. vertical cut tus- ! ing a plunger machine) across ths
 front of the pillar, sloping upward 60
 the center of the pillar, as described.
 A 15-ft. stringer is then placed, putting | up against the posts of two opposite sangway sets. as before, making tN 0
 stringers in place, one 1t. above the
 other. A segment set consisting Ci | two angles and a spreader is ILen placed between the upper and the
 tower stringers, and the upper string
 CT is blocked to the back. As the sec
 ond slice is being carried across the | pillar, stringeTs and segment sets are placed between the gangway sets as | before. Segment sets are used only
 at the top of the stope and are ior
 the purpose of keeping up the back while the ore is being taken out of I the pillar below. As the second slice is progressing from the front to the
 back of the stope, a third one is started below, in the same manner as before. These slices are progressively started at the front, so the ore will
 run toward the front part of the stOpe. as the only chute in one gangway is in front All the ore runs into the chutes without mucking until near the bottom: the ore in one corner of the stope must be shovled, as it will no J lon ,-ttf, int -rlar hA ell usually average 5 it. in thickness. and
 the stope n the side nearest the chute
 crosscut is longer than the opposite side. Plugger machines are used ex- clusively except in starting the slice.
 Often the top of the oretody ex-
 tends above the top stringers a little
 distance. In this case the ore is
 usually mined out after the segment sets are in place. and short stulls are used to catch up the back. If the ore
 is only to it. above the stringer.
 it is usually taken out before the stringer is placed in position.
 Each stope has several outlets. The manways of the raises serve as lad derways and also for the purpose of bringing timber into the stope. Usual ly there is a manway at the end of the gangway sets from the chute crosscut A timberway is partitidned off one corner of the manway with lin. boards and is used to bring tools and timber into the stOpe. The lad ders are staggered and inclined, hay ing a platform every 1t. The long stringers are usually lowered or hoist ed eff necessary through the man. way in front. which has vertical lad ders. When bringing a stringer into the stope from below. it is sometimes necessary to remove the cap in front of the raise, in order to get the stringer into the manway. Usually the stringer can be landed into the stope with little trouble.
 After the ore has been mined out of the pillar, tagging is placed over the ore on the first floor, and the space occupied by the pillar is Jagged
 1ff and filled with waste from the level above. A subraise is often run from the center of the back of the stope on an incline to one of the raises that extends to the level above, so that the waste will run directly to the center of the stope. The gang way sets are preserved. as they are used in mining the pillars on the op- posite side to the one just mined. Ar ter one pillar has been mined, and the space occupied by it filled with waste, the adjoining pillar is mined.
 The whole ore body is not all blocked out by raises, crosscuts and gangway sets before slicing is resort 1 ed to. but all these operations are going on progressively in different parts of the ore body at the same l time. Notifications of This Mining Method !
 The Mitchell torslice system IS | worked in some places with slight | qualifications The chute crosscuts are l driven at 20-ft. centers and directly | under where the gangway sets are to | be. instead of at loft. levels. This i obviates some mucking, as there is | row of chutes in each gangway set | Nearly all the crosscuts in ore at this | mine have to be timbered, so it was 1 considered cheaper to have the chute i crosscuts twice as far apart and dc | a little more mucking than to drive | the extra timbered crosscut As this | system was worked in the Oliver an6 | Irish Mag mines, some of the timbers , were taken out and reused. but the l character of ground would not permit | it here. This system has been used .