From Cradle to Grave, We’re Surrounded by Aggregates
Aggregates (sand, gravel, and crushed stone) are among the most ubiquitous minerals on the planet.
In fact, we are so surrounded by aggregate materials that it’s easy to overlook them. Think for a moment about your own life…
Were you born in a hospital? It was probably constructed from natural aggregate. Do you routinely travel on roads? The concrete and asphalt are composed of aggregate minerals. Your home, school and work place? All composed of aggregates.
The fact is, we live our entire lives dependent on an infrastructure created from concrete and natural aggregate minerals. And once this life is over, our remains are likely to be interred for eternity in a vault of aggregate.
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Why Do We Need Aggregates?
It is impossible to construct a city (or just about anything else) without using natural aggregate sand, gravel, and crushed stone.
Which is why annual production of aggregate minerals worldwide totals about 16.5 billion tons, making aggregate production one of the most important mining industries in the world.
Aggregate is needed to build and maintain all urban, suburban, and rural infrastructures including (but not limited to):
- Commercial and residential buildings
- Sidewalks and parking lots
- Factories and power generation facilities
- Water storage, filtration, and delivery systems
- Wastewater collection and treatment systems
Agricultural and Industrial Uses
Did you know pulverized stone is used in fertilizers and insecticides to enhance the growth of plants?
It’s also used in the manufacture of pharmaceuticals, sugar, glass, paper, plastics, floor coverings, rubber, leather, synthetic fabrics, glue, ink, crayons, shoe polish, cosmetics, chewing gum, toothpaste….well, you get the idea.
Stone (in one form or another) is used in practically everything we touch every day.
Aggregates are the most mined materials in the world. They’re mined in all 50 of the United States and in most countries of the world. U.S. aggregate production accounts for about half of our nonfuel-mining volume (that is, everything but coal). In 2014 alone, 911 million metric tons of aggregate materials were produced in the United States.
How Is It Mined?
Aggregate production essentially turns big rocks into little rocks and carefully sorts them by size. Excavating crushed stone or sand and gravel is dependent on the geologic characteristics and the extent and thickness of the deposit. Open-pit mining and quarrying methods commonly are used, although some stone is mined underground.
Quarrying and mining stone generally requires drilling and controlled blasting before the rock is extracted with power shovels, bulldozers, and other excavators. Sand and gravel deposits are usually unearthed with conventional equipment such as bulldozers, front-end loaders, and tractor scrapers. But the deposits may be dredged from streams or water-filled pits using hydraulic or ladder dredges.
Once the material has been extracted, it’s ready for processing. Processing plants are generally constructed on the site of the aggregate extraction. With quarried rock and large gravel, the processing often requires crushing. The video clip below demonstrates a massive “jaw crusher” in action:
After crushing, the aggregate is sorted to size. Silt and clay are removed by washing. At this stage, aggregate commonly is moved by conveyors to bins or is otherwise stockpiled.
Finally, the aggregate is loaded on trucks, railroad cars, barges, or freighters for shipment to the site where it will be used.
From there, it will be used for building and road construction materials…wallboard…glass…pots and pans… baby powder… household cleaners… makeup… medicines… paints… pencils….
The list is endless.