Retrac reaming bit

Retrac reaming bit

Published in www.miningmagazine.com

After blast holes are drilled in the tunnel face with hole diameters ranging from 43-51 millimetres, certain holes in the pattern are enlarged with a typical reaming bit to 76-102mm, depending on the blast and rock formation requirements.

With a standard reaming bit, the face designs have domes or narrow nose fronts, and are effective at enlarging a predrilled hole.

When they are retrieved out of the hole, however, at the end of the target hole depth, they often seize up due to the loose rock debris inside the hole formation.

With the new bits, the fins can effectively push out rock chips trapped behind the bit when the string is pulled from the blast hole, providing more efficient reaming operations.