20-foot-diameter blind shaft drilling

CIM Bulletin, Vol. 74, No. 830, 1981

R.P. CARONE Senior Design Engineer, and D.A. WHITLEY Project Engineer, Santa Fe Engineering and Construction Co. Orange, California

Shaft sinking by blind shaft drilling offers the mining industry a different approach to shaft construction. Benefits of blind drilling include less construction time and fewer safety problems while being economically competitive with conventional sinking methods under certain conditions in soft water-bearing formations.Technology and equipment are available today to drill blind shafts up to 20 feet in diameter and over 3,000 feet deep. This is an extension of proven techniques developed by private industry. To drill a 20-foot-diameter hole requires a specially manufactured hydraulic drill unit with a rated hoist of 2 million pounds and 500,000 ft/lb of torque.This brief paper will discuss the following aspects of blind shaft drilling:benefits;equipment for drilling;circulation methods;circulation rates;shaft alignment; andprogress rates to be expected.
Keywords: Shaft sinking, Drilling, Shaft drilling, Blind shaft drilling, Rotary drilling.