Saving on sand disposal: some metalcasters have been achieving disposal savings for their used metalcasting sand for more than a decade, but the game has grown and evolved.

Metalcasting sand isn't going to be used to build castles, yet. However, if you're looking to find some savings around your castle, providing your used sand to another industry for recycling might be the answer.

"It's a cost avoidance thing," said Mike Lenahan, president of Resource Recovery Corp., Coopersville, Mich., a cooperative that processes the sand from 30 different metalcasters in the state.

The key to entering the market of beneficial reuse of metalcasting sand is to understand the various applications that are available and the state regulations that govern them, and then determine whether they are a viable option for the location of your metalcasting facility and the amount of sand you can offer at any one time.

"Transportation is the killer of all deals," said Lenahan, who offered an example. "Using metalcasting sands in the production of Portland cement is a great application. However, if there isn't a cement kiln close, it isn't worth sending it."

Of course, cement kilns aren't the only place to recycle your sand (or have a processor send them). Successful applications through the years range anywhere from alternate daily landfill cover to engineered polymer composites.

Sometimes the Sand Sets

Today, some of the most promising and widely used applications of metalcasting sand are geotechnical, which includes building construction and road sub-base or embankment material.

"Sub-base is a great application," said Lenahan. "Metalcasting sands are really well suited for it based on the sieve analysis and grain distribution. It's a material that's not moisture sensitive, it's not susceptible to freeze-thaw, and it's a uniform material. Engineers like uniform and predictable materials, and these sands, when handled accordingly, provide that uniformity and predictability."

Unfortunately, geotechnical applications haven't received the widespread acceptance from regulators that has greeted the use of sand in manufactured products.

"Most states will approve the use of metalcasting sand for manufactured products," said Elizabeth Olenbush of Foundry Industry Recycling Starts Today, Mill River, Mass. "With respect to geotechnical applications, it's important to check the state rules."

As promising as geotechnical applications are, the volume of sand that smaller metalcasters can provide might limit their ability to participate in the application. Developers may need an extremely large amount of material quickly to complete projects. Therefore, unless you are providing your sand to a third party processor, which can combine your materials with like sands from others to build volume, you may have to pursue other avenues.

Don't Desert Them Just Yet

The success of any one application is never cut and dry. With so many factors--sand composition and volume, the location of your facility and local environmental regulations--weighing in to the success of a particular end use, don't rule anything out without first consulting your state's environmental regulations. Once you have determined that your materials are in compliance with those regulations, you can perform a market analysis, surveying the compatibility of your supply with local or regional demand.

Cement kilns need aggregate materials to produce their product, but this application may not be an option for individual metalcasters. First, your facility must be located very near a cement producer if you're to compete with the low cost of the aggregate they would otherwise use. On top of that, you have to contend with regulatory issues (according to Lenahan, some agencies want to reopen a kiln's air permit when it introduces new materials) and the forethought of cement kiln designers.

"You have a unique situation where cement kilns are generally running out of a nearby source, and most of them are located near a huge quarry," said Dan Oman, vice president of RMT Inc., Ann Arbor, Mich., a company that offers environmental engineering and construction solutions with an eye on health and safety.

In the early days of beneficial reuse, many thought, correctly, that they could use metalcasting sands in asphalt and ready-mixed concrete. These applications are still used today, but the nature of metalcasting sand makes them less attractive than was once thought.

Metalcasting co-products tend to exhibit finer grains than are found in the virgin sand that typically is used for construction purposes. Thus, if end users want to use metalcasting sand in place of heartier virgin, they often must combine it with a larger-grained material. In asphalt, metalcasting sand can be used as 7-15% of the mixture, depending on the product desired. In other applications, such as tennis courts and bike paths, metalcasting sand can constitute 40% of the mix, according to Lenahan.

Ready-mixed concrete also requires an alteration to the mix when it includes metalcasting sand; usually intermediate sized stones or gravel is added.

Like Sand Through an Hourglass 

Plenty of the proposed uses of used metalcasting sand have turned to dust in the developers' hands. Some applications even have been lost to semantic refinements. Many metalcasters recognize the use of sand as daily landfill cover as a suitable reuse application. They also might use the material for cap and closure when a waste area reaches capacity. Others will ask, if your sand is going to the landfill, is it truly being beneficially reused?

"The industry doesn't have a beneficial reuse program in order to get more sand into a landfill," Olenbush said. "It's to get sand out of a landfill." According to Olenbush, many metalcasters using their sand as landfill cover do not realize a cost reduction, as landfillers may not offer a lowered disposal fee for that application.

Lenahan notes that many times additional disposal fees in the form of taxes are waived in this instance.

Landfill cover can offer a significant cost avoidance when there is a shortage of alternative materials, according to Oman. In those cases, metalcasting sand can serve as the better option for landfill operators, even if the market forces them to offer a reduced disposal cost.

With a touch of engineering thrown in, developers can use sands in more advanced ways even within a landfill. To keep landfill contents from contaminating soils surrounding a waste disposal area, developers usually are required to install a lining composed of a less permeable material, such as clay. In addition to that barrier, most landfills implement a synthetic liner. Metalcasting sand can replace virgin sand as cover for that second layer to keep it from being punctured and penetrated by sharp objects.

"Metalcasting sand provides the right gradation and permeability for leachate to be tested and collected by the respective landfill," said Lenahan, whose company has been involved in such engineered landfill uses.

Education and, sometimes, a limited marketplace has kept other applications from fully developing. The use of flowable fill, a low-rigidity, concrete-like material, once considered one of metalcasting sand's most promising uses, has not been used in the capacity that some had hoped.

"Development of this application has more to do with the fact that virgin flowable fills have yet to reach their full potential," Lenahan said. "Contractors are used to filling holes with water main breaks with loose aggregate. If and when flowable fill takes off, metalcasting sand will still be desirable ingredients in the mix designs."

According to Lenahan, other applications like grouts and mortars have been overlooked in favor of obvious, higher volume applications.

Reuse in the Future

Reuse possibilities continue to develop, and in most cases regulations continue to change--however slowly--to reflect those developments. Soil-based applications, such as specialty and potting soils, are gaining substantial interest.

"This application is currently approved in a few states," Olenbush said. "Though, these are not broad-base exemptions. You still have to jump through hoops to get them approved." Ohio, Indiana, Pennsylvania and Michigan are among the states that have approved metalcasting sand for soil-based applications.

The U.S. Department of Agriculture's Agricultural Research Service is in the process of conducting a five-year research study to determine how well soils blended with metalcasting sand support plant life. According to Olenbush, they are close to delivering those findings, and if positive, they could open the door to additional agricultural end-use markets.

"There is a disconnect in what the regulations will allow and where there is the most value," Olenbush said. "One of the things that we're all working toward is to narrow that disconnect."

One of the upsides of soil-based applications is that limited quantities, available from smaller metalcasters, still can play a role.

"Soil-based applications hold the most promise because for a nursery or some kind of landscape shop, smaller metalcasters may be able to make enough sand," Oman said.

Lenahan believes that the manufacturing sector also has only begun to tap the potential of used metalcasting sand. His company has been involved in the manufacture of composite counterweights and is now looking into creating polymer composites that would function like other commercial plastics.

"When looking at how to reuse metalcasting sands, we all tend to grab the low hanging fruit," Lenahan said. "We are all challenged in coming up with the capital to invest in new technologies. With the cost associated with so many regulatory hurdles, our funds are limited, and our choices of which market to go after first must be good ones."

For More Information

"Metalcasters Attempt to Mold U.S. Policy," S. Gibbs, MODERN CASTING, June 2006, p. 34-37.

Visit www.foundryrecycling.org for more information on sand requirements and government regulations on the use of metalcasting sand.

See the AFS Sand Management Guide, Benchmarking Survey and State Tool Kit for information directed at metalcasters and state agencies on how to start a successful beneficial reuse program.

How to Cash in On Spent Metalcasting Sand

Reducing disposal costs on used metalcasting sand requires case-by-case analysis, as no two situations are exactly alike.

"When a metalcaster calls me, what I always suggest is to look for the closest market first," said Elizabeth Olenbush of Foundry Industry Recycling Starts Today. "The situation is so different from market to market and state to state."

Once you've found a nearby need for your sand, check your state's regulations to make sure that the application is allowed. There may be a complex permitting process involved in entering the market. Once you've answered any environmental questions, you'll need to address the second half of the sustainability question--is the project economically viable. Next, you're ready to prepare your sands for delivery.

"Metalcasters have to be prepared to deliver clean sand without garbage in it," Olenbush said. "All of us engaged in this issue would like to see more third party processors being used."