Print9.2.1 Mining Practices
All mining, past and present, has occurred on less than a fraction of a percent of the Earth’s land mass; and the mineral resources mined to date are a small fraction of the total estimated resources. We, as miners, cannot control societal demand for minerals, but we can take steps to ensure that resources are not squandered. We do this through a design and planning process that allows us to achieve the highest extraction rate that is safely possible. In surface mining, we normally have strong economic incentives to recover all of the ore above the cutoff grade. In underground mining we usually need to leave some resource in-place for ground support reasons, and this will limit the extraction ratio. Extraction ratios of 60% are not uncommon, although for some commodities, the ratio will be much higher. Remember that after we have finished mining a specific reserve, it is almost always impossible to go back at a later time to recover additional ore. It is often said that the resource has been “sterilized.” From a sustainability perspective, we want to ensure that we are not wasting the opportunity to recover all the resource than can be recovered safely and economically; and we do this through proper planning and design.
Mines receive permits to operate, and these permits typically define conditions of operation. The constraints imposed by the permits may include operating hours, noise levels, water usage and discharge, and so on. These limitations are generally in addition to regulatory constraints, such as the clean air standards. Regardless, it is in the company’s best interest to ensure that operations are always practiced within permit limitations.
Often mines are located near or in communities, and their appearance from public areas, e.g. roads and residential developments is a concern. The use of landscaped berms to completely shield operations from public view is a good practice, as are attractive and well-maintained entrances to the mine property. Admittedly, there are some large surface mines that cannot be shielded from public view, e.g. Bingham Canyon copper mine These are the exception, and even in those cases, steps should be taken to improve the appearance through increased green areas on the site and better management of waste and product piles.
Blasting practices at surface mines located near communities are always contentious. We’ll talk about this again under community relations, but the design guidance given in Module 6 is critical to minimizing the technical and public relations problems arising from blasting.
Reclamation is of course mandated by various regulations. Often, within the conditions of the regulations and permits, there is some leeway in timing and methods. In addition to the traditional operating considerations affecting reclamation, the view and perception of the public should be factored into the reclamation planning process. Minimizing both the extent of exposed areas and the time that they remain exposed prior to reclamation becomes important if you are concerned about the bearable in addition to the viable region of the sustainability diagram. Even in operations where much of the reclamation cannot occur until near the end of the mine life, e.g. an open pit mine, small actions can be taken to think about the placement of overburden and waste piles for example. It is likely that the placement of these piles will be driven primarily by mine planning concerns, but whenever possible, sustainability considerations, balancing the viable and bearable regions, must be part of the thinking process.