Silica (Dune) Sand from the Medicine Hat Area, Alberta

Dune sands from the Medicine Hat area in southeastern Alberta contain particle sizes predominating in the 50 to 100 mesh (0.297 to 0.149 mm) range. The chemical composition varies between 85 to 89 per cent SiO2, to 5 to 7 per cent Al2O3, 0.7 to 1.4 per cent Fe203, 0.6 to 1.5 per cent CaO, 0.2 to 0.5 per cent MgO, and 0.4 to 1.8 per cent loss on ignition. Mineralogically the sands contain more than 80 per cent quartz, approximately 10 per cent feldspar, and 5 per cent or more other minerals. Heavy mineral assemblages include goethite, garnet, hornblende and magnetite. The grains are mainly subrounded and commonly stained.

Beneficiation tests on the sands involved screening, washing, heavy liquid separation, magnetic separation, and acid treatment. The results of these tests show that heavy liquid and magnetic separation techniques are most efficient in reducing the iron content of the sands to a minimum of approximately 0.30 per cent in selected samples.