Development of the Cigar Lake Jet Boring Mining Method

Abstract

The Cigar Lake high-grade uranium mine in northern Saskatchewan is finally in operation after 25 years of test mining, construction, and mine flood remediation. Cameco Corporation, on behalf of a joint venture, is the operator.The Cigar Lake orebody is situated 430 metres below surface at the unconformity between metamorphic basement rocks and flat lying sandstone. Major technical factors influencing the mining method selection include ground stability, control of ground water, radiation exposure and ore handling. A 10 year test mine program resulted in the selection and validation of “jet boring”, a non-entry mining method accessing the orebody from below.Cigar Lake’s jet boring mining method involves several major steps; artificial ground freezing of the orebody and surrounding rock, new Austrian tunneling method (NATM) development of access crosscuts below the orebody, installation of cased pilot holes upwards through the ore, and ore extraction using a rotating high pressure water jet within the pilot holes. The resulting cavities are surveyed and backfilled with concrete. The ore slurry is ground and thickened underground, pumped to surface and trucked to the McClean Lake mill operated by AREVA Resources Canada Inc. for processing to uranium concentrate.This paper and presentation includes highlights of the development of the jet boring mining and ground freezing methodologies and the first two years of production.