SELECTIVE DISSOLUTION OF SYLVITE ORE USING MANGANESE AS A CATALYST
Mr Don Gendzwill ( - University of Saskatchewan), Mr Z. Szczepanik ( - University of Saskatchewan)
Solution mining of potash ore with concentrated brine has been proposed as a means to avoid large piles of halite tailings on the surface. Laboratory tests of 41% and 61% grade potash ore samples showed that concentrated NaCl brine can selectively leach sylvite from potash ore while leaving the original coarse-grained halite matrix in place but the rate of leaching is much slower than achieved with fresh water or weak brine. After leaching more than 150 hours, 98% of the original sylvite was removed from the samples creating high porosity that was partly filled and re-cemented with very-fine-grained new halite that crystallized out of the brine. Replacement of original sylvite with newly crystallized halite is a mechanism that transports halite from the surface to underground. A small amount of manganese added to the brine slightly improves the initial rate of sylvite leaching. The leached and highly porous rock samples, 97% pure halite, were still intact, did not disintegrate, and were strong enough to be easily handled and cut with a saw. It is not clear how such a sturdy framework of porous halite rock that remained after leaching would behave in an operating solution mine cavern.