This thesis is a report on the construction, calibration and use of the universal B.E.T. apparatus for the determination of the specific surfaces, and the adsorption-desorption isotherms of a vapour phase mercaptan on solid adsorbent systems. Examples are given for the determination of large (to 2000 m2jg) and small (200 cm2/g - 1 m2/g) specific surfaces. A gravimetric McBain-Bakr micro balance is incorporated in the B.E.T. apparatus for the determination of the adsorption isotherms of hexyl mercaptan vapour on synthetic sphalerite, zinc sulphide and zinc oxide. Adsorption isotherms are given for hexyl mercaptan on synthetic sphalerite at 25°C, 0.5°C and 50°C; on zinc sulphide at 25°C and 1.5°C and on zinc oxide at 25°C. All these isotherms are sigmoidal with a definite change in slope at the monolayero The amount of mercaptan adsorbed after the monolayer increases almost linearly with relative pressure to P/P0 = 0.8. Above this value the amount adsorbed increases very rapidly vrith relative pressure. Hysteresis loops appear in the isotherms for all adsorption-desorption cycles. These loops are completely reversible. It is not possible to desorb the mercaptan monolayer from any of the adsorbents even at elevated temperatures.

The applications and limitations of pillars in underground mines is a subject that is of great importance to many mining companies, both new and old, but unfortunately has received little attention in the mining literature. Where underground pillars are used, the determination of suitable sizes present a problem about which little is known. An attempt has been made to gain an understanding of the factors involved in this problem by reviewing both theoretical and practical information on the subject. With this at hand, an attempt has been made to analyse pillar designs used in the Elliot Lake Uranium District, Ontario.

Mining has been termed the industry where in capital is depleted to reap profits. In this respect it differs from other basic industries such as farming, fishing or logging, which are also concerned with the initial exploitation of natural resources. In these industries, certain precautions and practices are adopted in due course to encourage and allow nature to rejuvenate and replenish the area. Thus it may be periodically reworked indefinitely, once the proper rotation schedule is established. In the mining industry, however, a company which owns a certain area can mine that area once only, and in order to find new ore, must mine to ever increasing depths.

The first attempts to rationalize comminution were made by Rittinger in 1867 and Kick in 1885 (1, 2, 3, 4). Rittinger postulated that: “The increase of the surfaces exposed is directly proportional to the force required.” Kick countered that: “The energy needed for producing analogous changes of configuration in geometrically similar bodies of equal technological state varies as the volumes or weights of these bodies.” According to Rittinger, since the surface formed in each stage is double, the energy required to produce each successive stage increases in geometric progression, the ratio being two.

Mining is one of the oldest industries, but it is only during the last 50 years that operations have been carried to depths where problems of temperature and ground pressure require special study. Temperature problems can be solved by increasing the now of ventilating air and or conditioning the air by refrigeration. Controls of this nature are limited only by economic factors. Pressure-increases with depth, however, present a far more complicated and difficult problem. The stress distribution can only be postulated since measurement of stresses in rock in situ is at present only in the initial stages of development.

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