Aggregate consists of manufactured crushed stone and sand created by crushing bedrock, and naturally occurring unconsolidated sand and gravel. The infrastructure created using aggregate is a major contributor to our current standard of living. Maintaining our lifestyle, passing that lifestyle on to our progeny, and supporting others to achieve developed nation status, will require huge amounts of aggregate. This chapter describes the aggregate industry and sustainable aggregate resource management, including the complex environmental, societal, and social issues associated with the exploration, mining, processing, transportation, and recycling of aggregate resources, and the reclamation of mined-out aggregate deposits.
Production of aggregate
If aggregate is to be produced from new sources, certain conditions must be met.
1. Sand, gravel, or rock must exist in sufficient quantity and quality to make mining worthwhile, and it must be accessible to transportation systems and to markets.
2. The property must be of sufficient size to locate a pit or quarry and processing equipment, and be owned by a person or people willing to sell or lease it at a reasonable price.
3. The deposit must physically be able to be mined without causing unacceptable impacts to the environment.
4. The extraction and processing site must qualify for all necessary permits.
5. The approving officials and the public must be convinced that the operation can take place without adversely affecting the environment or their lifestyle. In other words, the operator must be able to obtain a ‘social license’ to mine.
6. The operation must be profitable considering all costs including: exploration, acquisition, permitting, operation, environmental controls, compliance with regulations, transport to market, and reclamation.
The production of aggregate involves extraction and processing of the raw material into a usable product, transport of that commodity to the point of use, and the reclamation of mined-out pits or quarries. The following is a general description of the production of natural aggregate.
Typical crushed stone processing plant.