A review of local and international heat stress indices, standards and limits with reference to ultra-deep mining

In order to plan effectively for ultra-deep mining (UDM) projects, a number of issues must be addressed, not the least of which is the provision of workplace environmental conditions that are conducive to safe and productive mining operations. Although many aspects of an ultra-deep mining environment would be much the same as those already prevailing in deep-level gold mines, the variations in barometric pressure to which workers are exposed would increase by virtue of increased depth. Of even greater concern are the anticipated engineering requirements to contend with a tendency towards higher workplace temperatures, which will result from the auto-compression of air and higher virgin rock temperatures at greater depth and will be complicated by longer delivery routes for cooling media and ventilation air. The costs of providing acceptable thermal conditions will be crucial for assessing the viability of ultra-deep mining, and will ultimately prove to be a major determinant in the decision on whether or not to proceed with such projects. It is, therefore, essential to determine what conditions can be regarded as acceptable, as well as the criteria and limits that should be adopted in assessing them. The important issues are clearly worker health, safety and productivity and, accordingly, an evaluation of local and international thermal standards is essential. This will satisfy the need for soundly based standards, criteria and limits for ultra-deep mining that are aligned with established norms, in order to ensure that UDM projects yield the required results without undue risk to workers, or the perception of such risks among workers, regulatory authorities or potential investors. A detailed review of the literature and other sources of information relating to standards and regulations and certain environmental limits, and of various heat stress indices and their use (both locally and in other countries) were investigated. This investigation was done to establish what heat stress indices do exist locally and internationally and which would be most applicable to the UDM environment. In establishing this, a comparison was done to find out what standards and limits relating to these identified heat stress indices were used in A review of local and international heat stress indices, standards and limits with reference to ultra-deep mining