ODDS’N’SODS — The value of hindsight

About 2 billion years ago, when this planet was still a chilling, uninhabitable place, a precambrian stream laden with uranium-rich gravels emptied into a lake or inland sea just north of what is today the northern shore of Lake Huron.

About 35 years ago, a prospector named Franc Joubin theorized that uranium could be had in commercial quantities from the buried and hardened gravels. He was right, of course, and within the space of about five years, something like 20 mines were drilling into the uraniferous paydirt under the rolling bushland of Elliot Lake, Ont.

Until recently, some were still at it. Denison Mines had its big operation on the shores of Quirke Lake, and Rio Algom had two mines: the Quirke II and Panel, both of which were across the lake from Denison’s. (Rio Algom’s Stanleigh mine, which is south and nearer the actual townsite, is still operating.)

The uranium deposits at Elliot Lake consisted of flat-dipping “reefs” of conglomerate beds similar to the South African gold deposits on The Rand. However, mining at Elliot Lake was complicated by the variable thickness and dip of the “reef.” This could range from 6 to 50 ft. in width, and from a flat pitch to an altitude of 45!.

Consequently, several systems were selected for extraction. Managers of the Rio Algom group of mines decided to establish both conventional track-mining and trackless procedures. Initially, the Pronto and Quirke mines were developed as track operations, whereas the Nordic mine was set up as a trackless venture. Later, the Panel mine came on stream and, as a trackless undertaking, immediately experienced problems.

The uranium-bearing conglomerate had been diamond-drilled from the ice surface of Quirke Lake in the winter. The initial deep holes established a thick, flat-lying bed suitable for trackless mining. Unfortunately, in the area where the two shafts were sunk, the conglomerate bed abruptly entered a steeply dipping formation, and, as well, the thickness of the reef became reduced. As it happened, the trackless units could not be adapted for the removal of ore from the stopes. To compound the problems, the timing of shaft completion, mine development and mill production was critical, as it affected financial-contractual agreements and the marketing of product.

Hence, an abrupt about-face was made, and conventional stope mining, employing jackleg drills, was adopted. At first, it was decided to have slusher-scraper arrangements in the stopes, with ore transported to crushers by trackless units. However, this required the driving of oversize headings on each level to accommodate the trackless haulage unit. This consumed both time and money. Meanwhile, the stoping system had to be adapted for ore-handling purposes and waste development methods adopted. This rendered mining costs decidedly unattractive and unacceptable.

There was left one alternative and one only: The Panel mine had to become a conventional track-mining operation employing jackleg-slusher stopes, standard ore chutes and rail haulage.

The conversion was accomplished almost overnight, credit for which rests entirely with a workforce led by exceptionally able mine captains. Soon, a drastic increase in ore tonnage production was achieved, and the Panel was on its way to becoming a model operation.

Fortunately, the upper segment of the flat-dipping area of the bed was entered by means of an incline shaft, so that some use could be made of the trackless equipment. However, the true worth of the mine was realized as a result of using jackleg drills and track haulage.

Hindsight indicates that a much more detailed program of surface drilling and analysis of the configuration of the conglomerate bed would have resulted in an initial track operation from the start. But, alas, hindsight is not present when final decisions are made at startup!