Casting answers & advice.

Q Our facility has been hauling our non-toxic sands to the landfill, but we are looking for alternatives. What markets are available for spent metalcasting sands and how should our facility go about recycling our sand?

Metalcasting sands are often a good fit for local construction applications. Physical characteristics of spent sand allow it to replace conventional sands in asphalt and flowable fill (a type of low-strength concrete). It also can be used as feedstock for portland cement manufacturing and as a substitute granular material for road and building bases, fills and embankments. An overview of each of these applications can be found in the Federal Highway Administration (FHWA) publication, "Foundry Sand Facts for Civil Engineers." More detailed information is posted under the Technical Applications section of the Foundry Industry Recycling Starts Today (FIRST) website, www.foundryfirst.org.

Other local market options include brick or concrete block, precast concrete products, grouts and mortars, abrasives and a variety of other more specialized markets. Typically, these market transactions develop because of local business relationships, where a manufacturer who uses conventional sand becomes aware that there is a local source of metalcasting sand.

A future market may involve blending green sands with recycled organic materials to create manufactured soils for landscaping and other horticultural purposes. In most states, this is not yet an approved usage. A federal research program is underway to determine the safety and suitability of casting sands for horticultural and agricultural use.

Preparing Sands for Recycling

Metalcasting facilities need to assess their sands as potential "products" in order to find a local market option. Key factors include quantity, types of sand (green vs. chemically bonded), frequency of generation, clay content, grain size distribution, segregation from other waste streams and overall cleanliness. Firms should institute best sand management practices if they are serious about alternatives to landfill disposal. Some markets will require that sands be screened to grain size. Others may accept a small percentage of core butts. Metal and all other non-sand-based materials almost always need to be removed.

Each market has unique technical requirements, so plant managers should assess the "fit" between their sands and the local construction markets. In addition to the normal tests that metalcasting facilities run on their sand systems, there may be other tests required to assure the sands will meet market technical requirements. Information on generic requirements can be found under Technical Applications at www. foundryrecycling.org

State Requirements

Metalcasting sands which pass the toxicity characteristic leaching procedure (TLCP) test are considered "non-hazardous solid waste" under the Resource Conservation and Recovery Act and are regulated at the state level.

State requirements vary, as do the types and frequencies of environmental testing required.

Approximately 30 states have some type of beneficial use determination process that metalcasting facilities need to follow to get their sands approved for recycling into another product or construction project. A number of states require individual permits. Generally, the appropriate agency contact can be found by searching for "beneficial use" on the state agency website.

Although there are no federal environmental regulations for non-hazardous metalcasting sands, both U.S. EPA and FHWA have designated this sand as a priority material for increased post-industrial recycling.

Information for this column was supplied by Foundry Recycling Starts Today (FIRST) and the AFS Environmental Health and Safety Div. 10.

Recommendations are the opinion of the AFS Technical Dept. based on referenced literature and experience. If you need assistance with a technical issue; fax or email your question to: Casting Answers & Advice, c/o MODERN CASTING, at 847/824-7848 or [e-mail].