Winter field test for heap leaching Carmacks copper ore in Canada's Yukon Territory

A heap-leach field test was conducted during the 1993-1994 winter season at Carmacks, Yukon Territory, Canada. The purpose of the test was to demonstr ate the viability of heap leaching Carmacks oxide copper ore in an arctic s etting on a year-round basis. The rest itself utilized a 5-m-diam crib load ed with 250 t of composite ore from the Carmacks copper deposit The ore was stacked to a total height of 7 m in the crib including 1 m of ore as an ov er-layer above the emitter system. This matched the plan for the commercial heap at the time when the test was started. The design also replicated an interior segment of the commercial heap. Leaching was done at a flow rate o f 0.2 L/min/m(2) using leachate at 21 degrees C. This temperature was maint ained with no external heat input other than normal process heat transferre d from electrowinning to the leachate via solvent extraction. Winter condit ions were quite typical of those expected at the mine site. The temperature leached -54 degrees C, while averaging -13 degrees C over a three month pe riod. In spite of some flow system problems, leaching continued unabated an d freezing was limited to the insulating ore ol er-laver and isolated point s near the outer crib walls. Thus, the test demonstrated that year-round he ap leaching of Carmacks copper ore is practical in an arctic setting.