A Method of Determining Recoverable Iron in Mixed Magnetite-Hematite Orebodies

CIM Bulletin, 1968

P. E. CAVANAGH, President, Premium Iron Ores Limited, Toronto, Ont.

The Davis tube test has been used for many years as a laboratory method for determining the magnetic iron recoverable from a magnetite iron orebody. This paper describes a method for determining the recoverable iron from ores of the Labrador Trough type, with the usual flow sheet utilizing spirals followed by magnetic separation. The mechanical structure of a metamorphosed iron ore, resulting from recrystallization over long periods of time, is the basis for the laboratory method developed. Similarities between the structures of such recrystallized ores and the structure of annealed and recrystallized steel are noted. A laboratory technique to determine the size of the different grains of gangue and iron ore minerals is described and the application of this information to arrive at recommended grinding techniques and flow sheets is demonstrated. The use of the method to determine recoverable iron in such ores is compared to actual iron recovery in the pilot-plant and commercial concentrations of the same ore. The use of a specified lower limit of recoverable iron as determined by this method, in order to design open-pit Iimits, achieves practical results when compared to designing a pit based on an arbitrary lower limit of total soluble iron. The Ungava Iron Ore deposits are used in giving an example of the resulting pit design changes.
Mots Clés: Balance Point Screen Size, Grinding of Labrador Iron Ore, hematite, magnetite, Hematite, Iron, iron ore, Iron ores, Ore, Ores, Spirals