Wednesday, April 16, 2014

Demand for Sand

These are boom times for the sand industry, which is actually a mixed blessing, resulting in high prices and even environmental risks. The Global Environmental Alert Service of the United Nations Environment Programme tells some of the story in a March 2014 report, "Sand, rarer than one thinks." As the report notes (citations omitted for readability): "Globally, between 47 and 59 billion tonnes of material is mined every year, of which  sand and gravel, hereafter known as aggregates, account for both the largest share (from 68% to 85%) and the fastest extraction increase ..."

To get a sense of the volume here,  consider this comparison: "A conservative estimate for the world consumption of aggregates exceeds 40 billion tonnes a year. This is twice the yearly amount of sediment carried by all of the rivers of the world, making humankind the largest of the planet’s transforming agent with respect to aggregates ..." Or to look at it another way, one major use of aggregates like sand and gravel is for concrete. "Thus, the world’s use of aggregates for concrete can be estimated at 25.9 billion to 29.6 billion tonnes a year for 2012 alone. This represents enough concrete to build a wall 27 metres high by 27 metres wide around the equator."  Sand and gravel are also used land in reclamation, shoreline developments, road embankments, asphalt, and by industries including glass, electronics, and aeronautics.

Dredging sand and gravel from oceans and rivers causes environmental disruption, which can in some cases become severe, leading to problems with erosion, greater vulnerability to storm surges, and destruction of habitat for plant and animals. "Lake Poyang, the largest freshwater lake in China, is a distinctive site for biodiversity of international importance, including a Ramsar Wetland. It is also the largest source of sand in China and, with a conservative estimate of 236 million cubic metres a year of sand extraction, may be the largest sand extraction site in the world. ... Sand mining has led to deepening and widening of the Lake Poyang channel and an increase in water discharge into the Yangtze River. This may have influenced the lowering of the lake’s water levels, which reached a historically low level in 2008 ..." (The Ramsar Convention is the nickname for the Convention on Wetlands of International Importance, which is an intergovernmental treaty for protection of key wetlands.) In general, economic growth in China has been one of the major reasons for the expansion of sand and gravel mining in the last decade.

Or to choose a more extreme case: "In some extreme cases, the mining of marine aggregates has changed international boundaries, such as through the disappearance of sand islands in Indonesia."
The qualities of sand and gravel matter for their eventual use. For example, "If the sodium is not removed from marine aggregate, a structure built with it might collapse after few decades due to corrosion of its metal structures. Most sand from deserts cannot be used for concrete and land reclaiming, as the wind erosion process forms round grains that do not bind well."

With a combination of research and development into alternative materials, along with different materials methods of landfill and construction, the use of sand and gravel could be reduced. Some possible alternative materials for various uses include quarry dust, incinerator ash, recycled concrete and glass, perhaps finding ways to use desert sand.

According to data from the U.S. Geological Survey, the U.S. economy used about 46 million tons of sand and gravel for industrial purposes in 2012, which represents nearly a doubling since 2003. In addition, the price of sand and gravel for industrial use rose from $18.30/ton in 2003 to $52.80/ton in 2012. Essentially, this kind of sand has a high silicon dioxide content, and a large portion of this run-up in demand is because this kind of sand is used in hydraulic fracturing, which now consumes about 62% of this kind of sand in the U.S.

Use of sand and gravel for construction purposes was much greater in the U.S economy, about 842 million tons in 2012. However, this was down from about 1,200 million tons per year during the housing and construction boom of the years leading up to the Great Recession. The USGS reports: "It is estimated that about 44% of construction sand and gravel was used as concrete aggregates; 25% for road base and coverings and road  stabilization; 13% as asphaltic concrete aggregates and other bituminous mixtures; 12% as construction fill; 1% each for concrete products, such as blocks, bricks, and pipes; plaster and gunite sands; and snow and ice control; and the remaining 3% for filtration, golf courses, railroad ballast, roofing granules, and other miscellaneous uses."

With all due apologies to the good people and productive firms working in this industry, it's a little difficult for me to imagine a more boring product than sand and gravel. As a first step toward getting out of my ivory tower and getting over this prejudice, I close here with some comments from a 1999 report by the U.S. Geological Survey, "Natural Aggregates—Foundation of America’s Future."

"Natural aggregates, which consist of crushed stone and sand and gravel, are among the most abundant natural resources and a major basic raw material used by construction, agriculture, and industries employing complex chemical and metallurgical processes. Despite the low value of the basic products, natural aggregates are a major contributor to and an indicator of the economic well-being of the Nation. Aggregates have an amazing variety of uses. Imagine our lives without roads, bridges, streets, bricks, concrete, wallboard, and roofing tiles or without paint, glass, plastics, and medicine. Every small town or big city and every road connecting them were built and are maintained with aggregates. More than 90 percent of asphalt pavements and 80 percent of concrete are aggregates. Paint, paper, plastics, and glass also require sand, gravel, or crushed stone as a constituent. When ground into powder, limestone is used as an important mineral supplement in agriculture, medicine, and household products. ... On the basis of either weight or volume, aggregates accounted for more than two-thirds of about 3.3 billion metric tons of nonfuel minerals produced in the United States in 1996."