Many industrial by-products commonly thought of as “waste”—including coal combustion products, ferrous and steel foundry sand and slag, cement/lime kiln dust, and wood and paper mill ash—have economic, environmental, and/or product-enhancement benefits that can be harnessed via collection and reuse, rather than disposal.
Beneficially reusing these by-products in various applications in place of other, sometimes virgin, materials can save landfill space/costs as well as the energy and emissions that can be associated with the manufacture of these other materials.
For example, reusing coal combustion products (CCP)—the fly ash, bottom ash, boiler slag, and flue gas desulfurization gypsum produced when coal is burned to generate electricity—can:
- Lower costs associated with coal ash disposal, generate revenue from the sale of coal ash, and produce savings from its use in place of other, more costly materials.
- Improve the strength, durability, and workability of materials, such as concrete.
- Reduce requirements for the use of construction materials, such as portland cement, whose production generates high levels of greenhouse gas emissions.
To learn more about coal ash recycling and reuse, see section immediately below.
- Foundry sand can be beneficially reused in place of virgin materials as fill material in road and construction projects, while foundry slag can be repurposed in low-strength concrete applications.
- Lime kiln dust can be used as a cementitious material in mortar.
- Wood ash has value as a soil amendment in home gardens.