Working together, foundry operators and their suppliers are finding successful approaches for identifying, selecting, and implementing technologies that improve these emissions problems. Reactions between the sand and the resins, solvents, and catalysts used to bind it are responsible for the various emissions, and within the metalcasting environment these have been considered "natural."
Clean-air regulations as well as workplace safety and health standards, however, have forced operators to address the issue. But, effective emissions reductions are not simply the result of regulation, a point made repeatedly by speakers at the AFS 2006 Conference on Advancements in Low Emissions Casting Technology. Jim Schifo of Keramida Environmental Inc. examined how regulatory reductions estimated by EPA's MACT background document do not reflect the ongoing impact of the regulatory process. Successful emissions control, it became clear, is the result of individual foundries' initiatives and the commercial development of new technologies.
There is "no one panacea in new binder technology for the vast array of foundry processes," stated Metal Technologies Inc. president and COO Keith M. Turner. Rather, he urged other operators to conduct extensive evaluations of market offerings for specific processes. That outlook was underscored by Jeet Radia, asst. vice president – Environmental with McWane Inc., who has particular experience in the evaluation/selection process. And, the practical impact of this approach was outlined by GM Powertrain process manager Donald Couture, who explained a complex selection process for binders that is effective and objective, without resorting to standardization that might lessen the effectiveness of the solution, or impact the process.
The Casting Emissions Reduction Program co-sponsored the conference with AFS. CERP has been conducting cooperative R&D to refine measurement methods for foundries, and to evaluate various emerging metalcasting processes and systems. The data it gathers for emissions from coremaking and moldmaking processes have been used by metalcasters to demonstrate compliance with permissible operating standards.
One of its recent research programs examined the Resin/CO2 process, offered commercially by Foseco Metallurgical Inc. as Ecolotec. The process involves a water-based alkaline phenolic resin. Both the binder and sand are gas-cured with CO2 to activate the coupling agent. It's a high-productivity process that Foseco says eliminates casting veining without sand additives. It also improves metallurgical quality by reducing carbon pick-up, keeps emissions low, is virtually "odor free" during the process, requires no curing gas scrubber, and has no flammable components.
One of the more recognizable names among new binders is GMBond, the protein-based product available from Hormel Foods Specialty Products. It's water-based and non-toxic; Hormel summarizes the composition as 50% carbon, 25% oxygen, 17% nitrogen, 7% nitrogen and trace minerals. It's in use by four U.S. customers, and Hormel claims foundries using cores made with the GMBond process note lower toxic emissions levels and lower energy costs because there is no need to bake-out the cores. "Testing by CERP has found that GMBond reduces VOC emissions by more than 90% in baseline comparisons to cores made with phenolic urethane resins," Hormel states.
Another emerging binder technology is Laempe's Beach-Box process, already in use by some German foundries. What is notable about this development, according to David Reich of Laempe+Reich, is that it also signifies the emergence of a new manufacturing process — a closed-circuit for coremaking and moldmaking that addresses all concerns for emissions, odors, and sand disposal. Beach-Box involves a magnesium-sulfide-based binder that is mixed with silica sand and heated. The mixture is introduced to a warm box to produce the core or mold, and after decoring the dried core sand is reclaimed and reconstituted with water. Total binder use is substantially decreased.