Some aspects of the physical properties of rocks in connection with ore mining

Abstract

Expansion of raw-material resources in the iron-ore industry will be accomplished mainly by opening new mines and reconstructing old ones. The greatest relative contribution to the output of ore will be made by open pits working the deeper parts of steeply dipping deposits. These will constitute 67-78~ of the total amount of rock excavated by the open system, and 85-93~/c of this will be ledge rocks. Whereas at present the depths of ironore mines do not exceed 150-190 m, many mines are planned which will exceed 500-700 m. Thus, in the coming 7-10 years, the expansion of ore recovery will involve an increase in the relative contribution made by open pits, a great increase in the depths of these mines, and a marked increase in the proportion of ledge rock in the total rock excavated. In these circumstances, special attention will clearly be paid to the development of more efficient techniques for extraction operations, and this will only be possible if we can acquire data on the physical conditions of mining.