The Mining Process
Site Evaluation and Preparation
Site evaluation and preparation requires planning to meet permitting requirements. Guidelines for clearing trees and vegetation; stripping, transporting, and storing topsoil and overburden; constructing fences, berms, buffer zones, roadways, and sediment traps; and constructing or installing permanent or portable processing equipment are followed.
Mining and Processing
Mining of crushed stone or sand and gravel is dependent on the geologic characteristics and the extent and thickness of the natural deposit. Open-pit mining and quarrying are most commonly used, although some stone is mined underground. Sand and gravel deposits above the water table are excavated with bulldozers, front-end loaders, tractor scrapers, and draglines. Deposits below the water table, including stream and lake bed deposits may be excavated with draglines or from barges using hydraulic or ladder dredges. Mining and quarrying stone generally require drilling and blasting, after which the rock is then transported to a processing facility on trucks and conveyors.
Processing plants are generally constructed on the site of extraction. Processing of mined or quarried rock requires primary and possible secondary crushing, depending on the sizes of aggregate needed. After crushing, the crushed stone and sand and gravel usually are sorted to size, moved by conveyors to bins or stockpiled.
The goal of reclamation is to return the land to a beneficial use. By planning reclamation before the aggregate is extracted, it can be mined with how the quarry will look when it is reclaimed. This can make it easier to turn quarries into scenic, lake-front property, wildlife parks, golf courses, office parks, roller coaster rides and the many other items a quarry can eventually become. Parts of the mine can be reclaimed while continuing on-going mining operations in some instances.
Reclamation procedures depend on the configuration and character of the area. Progressive reclamation typically involves the following three steps: terracing the pit or face walls during or after extraction, final shaping of the area by replacing and reconfiguring the overburden, and landscaping. Reclamation plans are most effective if operators and planners select a strategy that satisfies the land use needs of the community and at the same time provides an economic incentive for the operator.
Source: The National Energy Foundation, from the Out of The Rock program. If you would like additional educational information and materials, stop by and see them at http://www.nef1.org or call them at 801-539-1406