Sand and aggregate are two of the most commonly used natural resources in modern society to maintain the existing infrastructure and provide for future construction. After air and water, sand is the natural resource most used by human beings (Beiser). About 70 percent of the world’s sand is quartz formed by weathering and erosion. Sand has a myriad of uses in everyday products, such as glass, detergent, toothpaste, solar panels, and silicon chips; however, the bulk of the world’s sand is used for concrete in buildings and roads, and rail ballast as well. Highway agencies and municipalities are experiencing difficulties in locating suitable aggregate for new construction and long-term life-cycle performance objectives.
Recently, the world’s supply of readily available sand and aggregate has been diminishing due to demand. The production of cement is reported by 150 countries and reached 47 and 59 billion tonnes in 2010 (UNEP). For each tonne of cement, the building industry needs about six to seven times more tonnes of sand and gravel (USGS, 2013b). The production of aggregate has become more difficult over time due to depletion of suitable sources, transportation distances, and conflicting land uses (Not-in-My-Backyard/urbanisation).
Mine waste rock and mill tailings have the potential to lessen the sand and aggregate shortage, provided the source material meets the physical and geochemical criteria (soundness, hardness, strength, porosity, and specific gravity) and can be transported economically. The production of sand and aggregate from mine waste rock and tailings has the potential to offset a portion of the mine’s reclamation costs by using existing equipment, trained work force, environmental permits and authorisations, and infrastructure such as power, water, and access.
Alternatively, portions of the mining facility can be sold or leased to a sand and aggregate producer.
A mine operator can assess the potential for converting waste rock to a salable product by determining the physical and geochemical properties of rock types that will be encountered and consider selectively handling the material for concomitant or future uses. The physical and geochemical properties can be determined during resource drilling concurrently with other geochemical characterisation programs required for mine permitting.
Beiser, V., 2015. The Deadly Global War for Sand,
www.wired.com, accessed October 19, 2017.
United Nations Environmental Programme (UNEP). 2014. Sand, Rarer than One Thinks, March 2014.
U.S. Geological Survey Geologic Carbon Dioxide Storage Resources Assessment Team, 2013b. (USGS, 2013b)
Langer W.H., 2011, Aggregate resource availability in the conterminous United States, including suggestions for addressing shortages, quality, and environmental concerns: U.S. Geological Survey Open-File Report 2011–1119.
