Dumping on potash A Flood of problems

Relief from the crushing supply situation facing Canadian potash producers could come this year in the form of an “Act of God.” While the 6.7 million tonnes produced in Canada last year exasperated worldwide oversupply, production this year could be significantly lower with the closure of a 765,000-tonne-per-year mine at Patience Lake, Sask., near Saskatoon.

Operated by Potash Co. of America, which is 87,7%-owned by Rio Algom, the mine was closed earlier this year — the result of a continuing heavy influx of groundwater from a Prairie aquifer. A $20-million program to construct 14 bulkheads, cement plugs about 100 ft wide, in locations designed to protect the active workings in the mine was planned last November. However, accelerated flow rates of groundwater (up to 5,000 gal per min) forced the company to abandon the plan. A decision was made, instead, to construct bulkheads at the bottom of the mine’s two shafts to secure future access.

Now it’s back to square one. Feasibility studies will be necessary to determine the best way to re-develop the deposit in order to bring the mine back into production — a process that could take up to one year.

At another Saskatchewan mine, International Mineral & Chemical Corp’s K2 mine, problems started in December, 1985, with a temporary increase in water inflow of up to 10,000 gal per min. Additional pumping facilities were installed and extensive grouting was done from surface. A new form of chemical grout (a saturated solution of calcium chloride) was used to try and precipitate sodium chloride in the rock formation, acting as a grout to block water flow. Inflow was reduced substantially but has since increased. Grouting programs and backfilling with salt continue.