Recapturing the `lost art’ of narrow vein mining

Narrow vein mining. Something our fathers knew a great deal about but very nearly a lost art today.

To help remedy the deficiency, the Quebec Mining Association (QMA) recently sponsored a “narrow vein mining project.” QMA enlisted the help of CANMET (Canada Centre for Mineral and Energy Technology), Quebec’s Centre de Recherches Minerales and the mining department of Laval University. The project comprises three phases: methods, machinery and dilution. The first two phases have been completed and all three will be presented in three volumes at a mining symposium Feb. 20, 1992, at Val d’Or, Que. Until the late 1940s, the mention of mining in Canada automatically triggered the thought that if we were talking about gold mining, then we were dealing with vein mining. Was there any other kind of mining? (Not entirely accurate, perhaps, but close enough for the times.)

Since then, base metals have become the staple of the Canadian mining industry and with them a change in technique. No more winkling out ore with a jackleg. Now we have mass mining. Nothing less than underground quarrying with a dramatic increase in productivity.

It goes without saying that bulk methods are not suitable for narrow deposits with erratically distributed values. Some companies believed they could overcome narrow widths and spotty grades with low-cost bulk methods but it is a long shot and that thinking has contributed toward mine failures in recent years.

So how are we going to mine narrow deposits today?. Labor costs are too high for a return to the methods of the past. Besides, who is going to drill uppers in a narrow stope and be drenched from head-to-toe in drill cuttings for the privilege?

Undoubtedly, the solution lies in the elimination of the drill-blast cycle and the application of continuous mining. And, almost as important, mining from the top-down rather than the bottom-up. Gravity no longer favors the miner. The industry spends far more time and expense today fighting gravity than it receives in return.

None of these needed advances in technology are going to arrive overnight. Until that time does arrive, we will have to make do with improved stope design, accurate longhole drilling, tailored explosives and better methods for cleaning stopes.

How often this last point is neglected and how often do we leave behind the fine sand created by blasting and drilling because it is too difficult to gather? Yet this same material could well be the richest ore to come out of the mine.

The technological advances that have been made in the Transvaal gold mines of South Africa are striking. Prototype continuous miners have been tested underground and it may not be too long before commercial models become available. Nevertheless, some of the Rand’s earlier experimentation with longhole drilling might be investigated to advantage by narrow vein miners.