Controlling personnel heat exposure in Canada's deep and highly mechanized mines

摘要

Canadian mining companies, with ore reserves at depths of > 3000 m below surface, have identified controlling heat exposure as a major technical concern. At issue are an appropriate guideline and/or standard that can be used to determine whether a working environment is safe and the magnitude of ventilation and/or refrigeration that may be required. Consequently, exploring heat exposure issues is a major project within Canada's Deep Mining Research Consortium (DMRC). The DMRC is jointly funded by mining companies and all levels of government, municipal, provincial and federal. Additional members of the Consortium include Federal research organizations, university academia and Provincial health and safety regulators. In Canada, the wet-bulb globe temperature (WBGT) is the most common index that is currently being used to determine the suitability of a work environment and the need for a work-rest regimen. However, in mines, its application is being questioned where workers benefit from the cooling effect of a significant air velocity, have the ability to self-pace their work, and could be working in air conditioned enclosures. Other questions/concerns include: adequate protection for short-lived intense exertion; the effect of personal protective equipment; reduced cooling potential of denser air at depth; and acclimation, especially in winter when workers experience diurnal variations of up to 60℃. This paper describes a four year project that is underway including: a review of heat exposure guidelines; a mechanical and energy expenditure characterization of standard mining tasks; a survey of the environmental conditions in mines; laboratory simulation of the tasks under controlled conditions; laboratory evaluation of heat guidelines, their field validation; acclimation studies and an instrumentation evaluation.