This technical information has been contributed by
Olson Aluminum Castings

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Illinois Foundry Minimizes Silica Sand Usage

Olson Aluminum Castings

In light of the recent increases in the demand for silica sand, Olson Aluminum Castings is investing in ways to reutilize and ultimately reclaim the silica sand while augmenting its dedication to green initiatives. The fracking industry has dramatically increased the demand for the same grades of silica sand used by the foundry industry and is putting a strain on the supply while driving up the cost to the foundries.

"Several reports we are hearing from suppliers of silica sand [say] that the fracking industry is using ten times the amount of sands that have traditionally been utilized by foundries," said Mike Stahl, sales manager for Olson, headquartered in Rockford, Illinois. "When you get that kind of hit or pressure put on a particular resource, there's a significant impact on the cost. We are tasked with finding ways to offset this increase and factor this impact out."

There are no good substitutes for the silica sand, and so Olson has been finding ways to minimize the amount of sand required to be added to its sand system on a daily basis. "Specifically on our air set side, we are looking at ways of increasing the reclaim usage on that sand," said Olson. "Currently, we are studying the thermal reclamation process, whereby we actually bake out or burn out the binders that are in the sand after each molding cycle prior to reuse. So if you can burn the binders out, you can reuse the majority of sand and the reclaimed sand actually is optimized in its ability to mold well."

Additionally, there are added energy costs involved in thermal reclamation of molding sands, and these costs must be weighed against the ever-increasing cost of delivered silica sand while also considering the uncertainty of future sand availability. "Forward-thinking foundries are finding ways to reclaim," Stahl said. "The increase in the prices of foundry silica sand has to be responsibly accounted for. I think there are a number of foundries who may be actually missing the cue and likely do not realize how much this can affect their bottom line. It may prove to be too late before they're on top of it. By the time they realize there's a problem, they may have fallen behind the curve significantly," he continued. "Reclamation requires a capital investment and an outlay that some foundries can handle and others can't. There are going to be those who can't make the capital investment, and they will have a tough time offsetting the additional sand cost while continuing to send costly sand to the landfill."

Olson recently added 16,000 sq. ft. to its foundry dedicated specifically to "air set molding," which has enabled the company to expand the range of castings it can produce. "We are expanding not just in terms of size, but in terms of range as it relates to depth of draws and degree of detail that we are able to achieve. It adds flexibility to how we lay out and design our tool programs," Stahl said. The foundry has installed an 8-station molding turntable matched with a dedicated Palmer-designed mixer with a complete rollover and closing line. Four additional pouring lines have been added to accommodate the added molding capacity. Olson now has significantly more flexibility and range, Stahl said. "We're able to produce multiple jobs, along with different-sized jobs, simultaneously--all while contributing to minimizing setup and change-over time. By utilizing mold boxes and, in some cases, core boxes mounted to common transfer sleds, we can improve our change-over efficiencies and increase scheduling flexibility."

A significant amount of new machinery was added to support the expansion, including a dedicated shakeout deck used to break up the poured and cooled sand molds. Workers run the spent sand through a newly installed attrition mill to further process the sand into its original grain size, whereby they can reclaim and reuse a good portion of that sand. Several sand silos used for daily production, a mixer, turntable, roll over station, closing station, conveyor lines, overhead gantry cranes, and additional heat-treat capacity machines were all added to deal with the air set sand process, along with the increased production volume.

Olson markets itself as a "green foundry" and has taken a number of initiatives to further its dedication to green practices.

Of the approximately 100 tons of sand used on a daily basis in the "green sand" foundry, less than 200 lbs. of new silica sand is required to be added to the system daily. Green sand is returned to the sand muller and, with minimal processing and binders, is made ready again to produce molds.

Used core sands are the only sands currently transported from the facility to be used as landfill cover and road bed aggregate.

The process of using a no-bake core mold line with an Alphaset® binder system utilizes a resin binder that is water based, rather than involving petrochemicals, thereby dramatically reducing the amount of VOC and HAP emissions.

All of the aluminum that is processed and poured is shipped as a finished product, while all cut offs and non-conforming material are re-melted to be utilized for subsequent castings.

The foundry lighting systems were converted from high-pressure sodium bulbs to energy-efficient metal halide, providing brighter, whiter light with less wattage used. The foundry will save 56,284 kWh annually.

Heat generated during the melting process is utilized to heat the rest of the foundry during cooler months. Radiant heat from an adjacent heat treat furnace is used to keep the hot water quench tank in the company's heat treat process at an operating temperature of 170 degrees. Energy consuming operations, such as furnaces, are controlled by programmed timers thereby limiting wasteful demand on both natural gas and electricity.

"When you think about it, foundries for many years have been probably one of the early green-thinking industries because so many of the resources tend to be reutilized and reclaimed," Stahl said. "In many ways, green initiatives really make sense. They can and should be cost-effective. And if you're doing things well, you're actually going to take control of many of your cost factors and may actually drive many costs down."

This technical information has been contributed by
Olson Aluminum Castings

Click on Company Name for a Detailed Profile

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