Materials Characterization Paper 

In Support of the 

Proposed Rulemaking: 

Identification of Nonhazardous Secondary Materials That Are Solid Waste

Foundry Sand (used as ingredient in clinker manufacture) 

March 18, 2010 

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1. Definition of Foundry Sand 

Foundry sand is an industrial material generated by the metal-casting industry, which uses the 

sand to form a physical mold used in the production of metal products. Two general types of 

sand are used in metal casting: clay-bonded sand (green sand); and chemically-bonded sand: 

• Green sand is composed of naturally occurring materials that are blended together: high 

quality silica sand; bentonite clay as a binder; a carbonaceous additive to improve the casting 

surface finish; and water. Due to the carbon content, green sand is actually black in color 

and adheres together due to the clay and water content. Green sand molds comprise about 90 

percent of the casting volume in the United States. 

• Chemically-bonded sand does not employ a clay binder. Instead, chemical binders are used 

to cause the sand to hold its shape during the introduction of the molten metal into the mold 

and the cooling of the casting. Chemically-bonded sand is generally light in color and coarser 

in texture than clay bonded sand, and accounts for only 10 percent of casting volume in the 

United States. Foundries use chemically-bonded sand in core-making, where high strengths 

are necessary to withstand the heat of the molten metal (FIRSTb). 

After multiple uses in castings, the sand becomes unsuitable for castings and is either disposed of 

in landfills or beneficially used in other applications, including use as an ingredient in the 

manufacture of portland cement. 

2. Annual Quantities of Foundry Sand Generated and Trends in Generation 

(1) Sectors that generate foundry sand: 

• The metal-casting industry, represented by NAICS code 3115, is the sole 

generator of spent foundry sand. 

(2) Quantities and prices of foundry sand generated: 

• According to the American Foundry Society (AFS), a metal casting industry 

group, the metal-casting process generates 9.4 million tons of foundry sand 

annually (Oman, 2007). 
Foundry Sand 

 

(3) Trends in generation of foundry sand: 

• The generation of foundry sand generally tracks with the manufacture of cast 

metal products. Despite increased foreign competition, the metal casting industry 

expects modest growth to continue. Sales of metal castings are expected to grow 

14 percent over the next three years from $33 billion in 2005 to $37.7 billion in 

2008 (Industrial Metal Casting). 

3. Uses of Foundry Sand 

(1) Ingredient uses of foundry sand: 

• Spent foundry sand can be used in the manufacture of portland cement clinker. 

Most foundry sands are high in silica content and can serve as a potential 

alternative silica source in portland cement clinker production. In addition, 

portland cement clinker production requires certain minerals, such as iron and 

aluminum oxides, both of which are found in many spent foundry sands 

(FIRSTa). Brass foundries create sands that can be hazardous under RCRA (if 

disposed of) due to metals content and, therefore, are outside the scope of this 

report (EPA, 2002). 

• According to the portland cement industry, foundry sand can be beneficially 

reused in the manufacturing of portland cement when it possesses the following 

properties: silica content of 80 percent, low alkali levels, and uniform particle 

size. In addition, large quantities of foundry sands must be available for it to be 

used by Portland cement manufacturers (FIRSTa). 

(2) Non-combustion uses of foundry sand:

• Spent foundry sand can be used as a substitute for virgin sand in road base, 

structural fill, flowable fill, soil amendment, or as the fine aggregate portion of 

concrete or hot-mix asphalt (FIRSTb). In addition, some sand can be used as a 

high-end additive to industrial materials, such as plastics, to provide specific 

textures and colors (Olenbush, 2006). 

(3) Quantities of foundry sand landfilled: 

• AFS estimates that in 2006, 6.8 million tons of foundry sand were disposed in 

landfills. This quantity includes sand used as a landfill daily cover (Oman, 2007). 

(4) Quantities of foundry sand stockpiled/stored:

• The sources consulted for this paper did not provide available information 

concerning whether significant quantities of foundry sand are stockpiled or stored. 

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Foundry Sand 

 

Exhibit 1: Overview of Generation and Use of Foundry Sand in 2007 

Annual Quantity Used as 

Ingredient Annual 

Quantity 

Generated Cement Kilns Other 

Annual 

Quantity 

Landfilled 

Annual 

Quantity in 

Other Uses 

Total 

Quantity 

Stockpiled 

Commodity 

------------------------------------ Short Tons -----------------------------------

Foundry sand 9.4 million Undetermined None 6.8 million 2.6 million Undetermined

Sources: 

Oman, Alicia. American Foundry Society (AFS), personal communication, 12/21/07. 

AFS, August 2007, Foundry Industry Benchmarking Survey, accessed at: 

http://www.strategicgoals.org/benchmarking/foundryresults8-7.pdf. 

Notes: 

Detailed quantitative data on the various beneficial use applications of foundry sand have not been well 

documented in the past. In an attempt to address this issue, AFS recently conducted a benchmark survey to 

collect information from the foundry industry on the specific quantities of spent foundry sand being beneficially 

used in different applications. The survey results indicate that none of the respondents are currently using foundry 

sand in clinker manufacture. According to the Portland Cement Association, however, foundry sand is being used 

by a number of North American cement kilns (FIRSTb). 

4. Management and Combustion processes for Foundry Sand 

(1) Types of units using foundry sand:

• When used in clinker manufacture, foundry sand is fed into cement kilns with 

other raw material feed. No other combustion applications appear to use 

significant quantities of foundry sand as an input. 

(2) Sourcing of foundry sand:

• In some cases, cement manufacturers obtain foundry sand through direct 

agreements with foundries, most of which are located in certain states, including 

Illinois, Wisconsin, Michigan, Ohio, and Pennsylvania (Turner Fairbank Highway 

Research Center ). Some foundries market their spent sand through a third-party 

or a cooperative instead of selling directly to the end-user. The majority of 

foundries are small businesses that generate small quantities of spent foundry 

sand. Through arrangements with multiple foundries, cooperative brokers/third 

party processors may be able to provide sufficient and consistent amounts of spent 

foundry sand to support the need of cement kilns. If a cement kiln uses a third 

party broker, the broker will pay the foundry for the foundry sand, but in some 

cases the kiln purchases the sand directly from the foundry (Lenahan, 2007). 

(3) Processing of foundry sand: 

• Foundry sand used in portland cement manufacturing must be separated from 

other foundry by-products through a series of screens (FIRSTa). The oversized 

material that does not pass the screens is termed "core butt" and consists of 

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Foundry Sand 

 

chunks and grains of coarse sand and scrap metal (FIRSTb). Most portland 

cement plants also require that core butts be ground to a uniform grain size 

(FIRSTa). Vibrating screens and a ball mill are used to further separate the 

components of this stream and to crush the oversized chunks of sand. Through use 

of a magnetic separator, metal in the stream is removed. 

(4) State status of foundry sand use as ingredient: 

• At this stage, we have not identified any states that have specifically given 

beneficial use designation to the use of foundry sand in clinker manufacture, or 

that prohibit use of foundry sand in clinker, but we have not performed an 

exhaustive investigation of state activities and regulations. 

5. Foundry Sand Composition and Impacts 

(1) Composition of foundry sand:

• Spent foundry sand consists primarily of silica sand, coated with a thin film of 

burnt carbon, residual binder (bentonite, sea coal, resins) and dust (Turner 

Fairbank Highway Research Center). Spent foundry sand may also contain heavy 

metals and phenols that are absorbed by the sand during the molding process and 

casting operations. Phenols are formed through high-temperature thermal 

decomposition and rearrangement of organic binders during the metal pouring 

process. The presence of heavy metals is greater in foundry sands generated from 

nonferrous foundries. Spent foundry sand from brass or bronze foundries, in 

particular, may contain high concentrations of cadmium, lead, copper, nickel, and 

zinc (Turner Fairbank Highway Research Center). 

(2) Impacts of foundry sand use:

• In clinker manufacture, foundry sand partially offsets the need for virgin silica, 

iron, and alumina sources. Thus, using foundry sand in the cement kiln can reduce 

the unit consumption of virgin feed stock materials and related emissions. 

• The specific lifecycle impacts of foundry sand use as a raw material in clinker 

production are not evaluated here because of uncertainties in lifecycle scenario 

development. For example, it is difficult to determine the replacement ratio 

between foundry sand and other raw feed materials in clinker production. Thus, 

the correct quantity of material to be modeled is unclear. In addition, foundry 

sand may substitute for a variety of virgin raw materials as well as other 

secondary materials (e.g., blast furnace slag, CCPs, cement kiln dust, etc.); the 

choice of material often depends on location-specific factors such as the 

proximity of material sources to the cement kiln and relative availability of 

different materials. Avoided upstream impacts depend heavily on the specific 

material being displaced in the lifecycle scenario. 

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Foundry Sand 

 

References 

American Foundry Society (AFS), About Metal Casting, accessed at: http://www.afsinc.org/content/view/62/122/. 

American Foundry Society (AFS). August 2007. “Foundry Industry Benchmarking Survey: Industry Practices 

Regarding the Disposal and Beneficial Reuse of Foundry Sand – Results and Analysis.” Accessed at: 

http://www.strategicgoals.org/benchmarking/foundry.html. 

Foundry Industry Recycling Stars Today (FIRSTa), Foundry Sand in Portland Cement Manufacturing, accessed at: 

http://www.foundryrecycling.org/TechnicalApplications/ManufacturedProducts/PortlandCement/tabid/173/

Default.aspx. 

Foundry Industry Recycling Stars Today (FIRSTb), What is Recycled Foundry Sand?, accessed at: 

http://www.foundryrecycling.org/Home/WhatisRecycledFoundrySand/tabid/294/Default.aspx. 

Industrial Metal Casting, “Casting Industry,” accessed at: http://www.industrialmetalcasting.com/castingindustry.html. 

Lenahan, Mike. Resource Recovery Corporation, personal communication, April 27, 2007. 

Olenbush, Elizabeth. FIRST, personal communication, April 2006. 

Oman, Alicia. American Foundry Society (AFS), personal communication, 12/21/07. 

Turner Fairbank Highway Research Center and the Federal Highway Administration, User Guidelines for Waste and 

Byproduct Materials in Pavement Construction, accessed at: 

http://www.tfhrc.gov/hnr20/recycle/waste/begin.htm. 

US EPA, Beneficial Reuse of Foundry Sand: A Review of State Practices and Regulations, December 2002. 

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