Measuring 8 m in diameter and 439 m deep, the new access shaft at Jim Walter Resources’ Number 7 coal mine in Alabama, is a major feat of engineering. It is also just possibly a world record in large diameter raiseboring.
It was on December 7, 2014, that Raisebor, a division of Cowin & Company Inc., completed the record raise using its Atlas Copco Robbins 123RH C raiseborer equipped with a multi-modular wing system (MMWS) reaming head.
The task was to provide the mine with a utility and access shaft closer to the working face to increase efficiency. It was taking roughly one hour for workers to reach the face which meant that almost 25 percent of every 8-hour shift was being lost to commuting.
It was Raisebor’s third project after acquiring the Atlas Copco machine. The first two were 6 m in diameter so the new project was not only much larger but also more complicated. To start with, a massive concrete foundation, 9.7 m thick, had to be built on the surface, prior to building the platform for the machine to stand on, requiring the removal of 2 500 m3 of material.
Designing The Moose Rick Sidwell, General Manager of Raisebor, worked with the Atlas Copco design engineers to develop the huge reamer head. “They respected my input.
We discussed what needed to be done to make it better,” he says. “We put extra wing cutters where I felt they were required and I appreciated the flexibility that was demonstrated by Atlas Copco.”