Canadian silica resources: a study of the processing of Ontario Potsdam sandstone for glass and foundry sand

CIM Bulletin, Vol. 79, No. 887, 1986

R.K. COLLINGS, Head, P.R.A. ANDREWS, Research Scientist, Non-Metallic Minerals Section, Mineral Processing Laboratory, CANMET, EMR Canada, Ottawa, Ontario

In cooperation with the Ontario Ministry of Natural Resources, selected deposits of Potsdam sandstone in the Ottawa-Kingston area were core-drilled and evaluated by CANMET as potential glass and foundry sand. Analyses of cores ranged from 84.6 to 98.5% SiO2, 0.09 to 0.65% Fe2O3, and 0.07 to 2.10% Al2O3. The cores were largely composed of white to grey, relatively tough sandstone. Impurities included iron as pyrite, iron oxides and staining on the quartz grains; carbonates as calcite; and aluminum oxide as feldspar. Beneficiation included size reduction to grain size, about 600 pm, by jaw, roll and cone crushers, and grinding in a muller-mixer. Removal of fines was achieved by attrition scrubbing and washing. Further removal of impurities was achieved by reverse flotation of pyrite, iron oxide, feldspar, and carbonate minerals employing both anionic and cationic collectors. Flotation resulted in a substantial improvement in the quality of most samples; analyses of quartz concentrates showed 98.5 to 99.7% SiO2, 0.022 to 0.156% Fe2O3, and 0.07 to 0.62% Al2O3. Further reduction of the iron content by wet magnetic separation and acid leaching also was investigated. On the basis of the samples submitted, sandstones from six of the seven deposits studied have potential as sources of glass sand. Foundry sand tests were inconclusive because of the small quantities available for study.
Keywords: Industrial minerals, Silica, Potsdam sandstone, Glass sand, Foundry sand, Beneficiation, Processing