Coal Age

OCT 2015

Coal Age Magazine - For more than 100 years, Coal Age has been the magazine that readers can trust for guidance and insight on this important industry.

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control panel, rotation backs down. "The programming on this drill is really Johnny- on-the-spot accurate," said Bass. At one time there was a 20-ft-long, 5-ft- thick rock that broke free from the face, causing a delay in drilling. It took time to lower the cutting head and replace cutters that were smashed, but people were never in harm's way. Drill superintendent Willy Hicks said the drill performed well throughout the project. He gave quite a bit of credit to t h e o p e r a t o r s w h o k e p t a n e y e o n t h e controls and made the process look easy. On average, the drill advanced at 5.5 i n . p e r h o u r , b u t f o r m a t i o n c h a n g e s made drilling speed inconsistent. The formation could show a foot of coal then 4 in. of sandstone. In a 24-hour period, t w o s h i f t s m i g h t h a v e 8 t o 1 0 f t o f advancement. This was a little ahead of the preplan estimates of 3.7 ft per shift or 7 f t p e r d a y . D r i l l i n g a d v a n c e d b e t t e r than projected throughout the project. "This is an amazing piece of equip- m e n t , w i t h i t s r o d h a n d l i n g s y s t e m , " Hicks said. "The old way we had to move pipe with a chain hoist, now we have a modern rod handler. It grips the pipe up to 2,000 psi to thread on the connection." T h e d e s i g n o f t h e M M W S r e a m e r , nicknamed the "Moose," was based on t h e l a r g e s t e x i s t i n g r e a m e r i n A t l a s Copco's raise bore tool line. It consists of a 48-in.-wide core and two 48-in.-wide intermediate wings. Up to eight outer w i n g s e x t e n d t h e c u t t i n g c a p a c i t y t o 26 ft. The outer wing design was intended to allow efficient cleaning of the head, which uses five-row Standard Magnum cutters paired with 1-in. spacing. The wings were designed to be removable to make underground transport easier. It can be operated with as few as four wings. Raisebor discovered that six wings were optimal for keeping the head clear of rock buildup. The 14.1-in. Atlas Copco Secoroc cut- ters weigh more than 400 lb each. Of the 50 cutters used, 35 went the distance. The 15 that needed to be replaced were o n l y c h a n g e d b e c a u s e t h e y h a d b e e n d a m a g e d b y t h e l a r g e r o c k f a l l o n t h e head. For Sidwell, the objective throughout the project was not to lower the head unless absolutely necessary. The process could have taken two weeks of advance- ment because tripping up and down would take that much time. Sidwell worked with Atlas Copco to develop the head. "Atlas Copco respected my input. We discussed what needed to be done to make it better. We put extra wing cutters where I felt they were required and I appreciated the flexibility demonstrated by Atlas Copco." The cutting face is so wide that for each rotation of the inside cutters, the outside cutters will rotate 22 times. However, the cutters showed little wear regardless of location on the face. Rotation speed can be set at the control from 0 to 50 rpm while the pilot is drilling and from 0 to 7 while reaming. The crew found the r a i s e b o r i n g c o n t i n u e d 20 October 2015 Raisebor's James Bass operates the 123RH C raise boring machine from the quiet comfort of its remote opera- tor station. Willy Hicks, drill superintendent.

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