Pioneer makes the grade

Ewart Langille, the geologist and chief engineer at the Pioneer gold mine in British Columbia, was a tyrant in matters concerning ore grade control.

Hughie, as we called him, graduated as a geologist from the University of British Columbia in 1925 and worked at the Premier gold mine for 23 years before coming to the Pioneer mine in 1948.

One of Hughie’s first jobs was to address problems in the 27 vein. As a result, he began lateral development on six levels. Later, raises were driven at 100-ft. centres along strike of the 27 vein.

In order to obtain the average grade of the ore, Hughie had a crew patrol the underground mine every day to sample ore faces. The samples were delivered to the assay office for analysis, with results delivered to Hughie the following day. First, he reviewed the entire list, then passed the summaries to Jim MacNulty for editing and posting on the assay plans. Jim entered the assays in the log book and calculated updates for the block.

If the assay results were sub-par or excessive, Hughie would refer to the block’s ore grade files, then summon foreman Bob Ekloff for his opinion. Perhaps there was excessive dilution in the mining or maybe the assays were too far out of line. In any case, it was Ekloff who had to explain the results. Hughie was abusive if there was dilution — he demanded that the miners stay on the vein.

The frustrating details were then passed to me, and I would enter all the current assays into the block files for each stope. This upgrade demanded tedious calculations. After I was finished, Hughie would pass a copy of the summary to the manager, Jack Graham, and to Ekloff.

If there was a major discrepancy between the mill heads and the mine assays, Hughie would request the manager meet with the shift supervisors and mill superintendent to address the situation.

Of note was the reduction by Hughie of all high-grade assays to the mine average before posting. He called them “erratics” and would not permit them to influence the mine grade block values. The mill received the benefit, as any “erratics” would be added to their production totals. Yet, over the year, this situation would return to an acceptable balance so that Hughie was vindicated in his judgment and control of the mine’s ore grade.

— The author, a retired mining engineer, resides in Vancouver, B.C.