Foundry waste beneficial to other industries
The foundry industry is one of the greatest recyclers; however, it generates many waste products that end up in landfills when, in fact, they can be used in several applications, says US Department of Agriculture research soil scientist Robert Dungan.
Speaking at the 2013 South African Metal Casting Conference, in the North West, on March 14, he noted that there were solutions for waste, such as moulding sand, slag and furnace refractory, produced by the foundry sector. He noted that foundry sand was the most common waste in the industry and that it could be used in several geotechnical and agricultural applications.
Waste foundry sand, in particular, has many beneficial uses and can be incorporated into asphalt, concrete, construction fill, pipe bedding and road bases. It also has agricultural and horticultural uses, such as potting and as speciality soils. In direct land applications it improves soil texture and, as topsoil, it is used in landscaping and turf grass.
Foundry sand can be used in manufactured soil and this mixture can be used to successfully grow vegetables that are safe for human consumption, grass and other plants.
When asked about the risks of foundry sand, Dungan said a risk assessment was conducted by the US Environmental Protection Agency in a home-garden scenario, which found that the metal concentrations in foundry sand were similar to the levels found in native soil. Further, foundry sand has low dioxin, polycyclic aromatic hydrocarbon and phenolic concentrations. The assessment also revealed that most ferrous and aluminium-foundry sand is safe for use in soil-related applications. The waste sand can also be used in green-building applications. Slag, which is the by-product of smelting ore, was another valuable waste material, noted Dungan.
The use of foundry waste will benefit the industry, as raw materials and energy are conserved, while disposal costs are lowered. The pollution of soil, water and air resources will be reduced and the competitiveness of foundries will be improved.