Odds ‘n’ Sods — Waiting for the cake

Production of yellow cake from the Quirke in Elliot Lake, Ont., began in the summer of 1956, and expectations were high.

During the break-in period, all systems appeared to function and perform as planned. The underground mine reached its production quota of 3,000 tons per day at an ore grade that confirmed reserve grade figures. The mill, meantime, rose to a daily capacity of 3,000 tons at head grade value, with some dilution, and this appeared to coincide with mine output. The mine was using an open-stoping system and the mill was a leaching operation.

In order to “bed down” the orebins and ballast the thickeners, aeration and leach tanks, the mill required a large portion of the initial feed. We would have to wait, therefore, before the appearance of uranium oxide from the leached feed. The days passed quickly, and attention was directed to the precipitation section where the yellow cake would appear.

Several days passed without any evidence of product from the precipitate tanks. Routine sampling and analysis continued in all areas of the mine and mill. A week without product passed and the mine’s management became concerned. When a second uneventful week slipped by, management became worried.

Samples were reprocessed, sampling was increased, the weightometer scales were re-standardized, procedures were reviewed, dilution surveys were instigated and leaching methods were analyzed; there was no apparent discord between mine and mill. When three weeks passed without the appearance of yellow cake, the consultants arrived. All systems were placed under 24-hour surveillance and meetings were frequent.

Unspoken thoughts and tacit accusations created tension at the operation: perhaps the reserve grade was a fabrication; perhaps the mill system could not process this type of ore; perhaps the operational groups didn’t measure up.

Then again, perhaps all would be well.

One morning, following 20 days of doubt and aggravation, Jim Engstrom, the mill foreman, phoned me. “You ought to see it!,” he exclaimed. “We have yellow cake coming out of our ears. We can’t contain the flood of product, it’s coming so fast.” He was clearly relieved.

I felt as if the weight of the universe had been lifted from my shoulders, and wasted no time in passing on the news of our success and renewed credibility.

— The author, a retired mining engineer and regular contributor to this column, resides in Vancouver, B.C.