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Utilization of Dynamic and Physical Properties of Ice in Underground Mining Operations

Published online by Cambridge University Press:  30 January 2017

Henning Fangel
Henning Fangel*
Affiliation:
Svedala-Arbrå A.B., Svedala, Sweden
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Abstract

In sub-level caving mining operations, the lateral walls cave in. This results in dilution of the mineral content of the produced ore by 15%-20% waste rock. Also 15%-20% of the valuable ores are lost in the caved wall material that is left behind in the mined-out rooms. Placing ice, in the form of a small glacier, in the mine-room before the lateral walls start to cave, permit complete recovery of ore reserves without dilution. The glacier will advance at a rate permitted by ore extraction processes, in accordance with glaciological theories and laws.

Volumes of ice that are required may be calculated from ore extraction rates, power consumed in the mine, ventilating air volumes and temperatures, specific heat and thermal conductivity of the lateral rock. The required ice volumes can be produced through natural freezing of water, where the winter temperatures regularly fall below 0°C for a predictable period every winter. Use of ice as a mining aid reduces costs of the ore extraction process by about one-third and increases value of the produced ore by about 20%. Thus, the value of a given orebody is increased by about 30% relative to the values experienced in the most efficient mines of today.

Type
Abstract
Information
Journal of Glaciology , Volume 19 , Issue 81 , 1977 , pp. 672
Copyright
Copyright © International Glaciological Society 1977

Discussion

J. W. Glen: How safe are the procedures you are proposing? Is there a danger of ice falling on the men or machinery mining below? Is there a danger of running out of ice at the top with consequent rock-wall falls?

H. Fangel: The proposed procedures are as safe as tunnelling, and safer than any other known mining method. Men and equipment will never enter under uncontrolled roof nor have to load or secondarily blast caved rock, because they do not occur, according to the method. Men and machines will not have to work outside the cross cuts or drifts. Ice pressures against piles of blasted ore in the ore-extraction zone are high and ice is found in its plastic state. The whole process is based on and depends upon the ice having the potential of moving into the mine void faster than extraction rates plus melting losses.

A reservoir of ice ought to be produced in the pit (or day opening) in order to bridge mild winters or water shortages. In later stages of the life of an ore body when it is assured that the volumes of ice already inside the mine will last for the whole remaining life of the mine, further provisions of ice may be suspended. If the rock wall should cave in, this will in no way influence the operations deep inside the mine. Actually, closure of the mine and termination of operations may be prepared by dumping waste-rock, tailings, etc. on top of the ice, and then filling up the open-pit to prepare for reclamation of the mine site.