RECLAIMING FOUNDRY WASTE GREEN SAND AND BAGHOUSE DUST VIA ULTRASONIC IRRADIATION, ADVANCED OXIDATION, INDUCED CAVITATION AND DISCRETE PARTICLE SETTLING
Open Access
- Author:
- Fox, John Thomas
- Graduate Program:
- Environmental Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- None
- Committee Members:
- Fred Scott Cannon, Thesis Advisor/Co-Advisor
Fred Scott Cannon, Thesis Advisor/Co-Advisor
William D Burgos, Thesis Advisor/Co-Advisor
Robert Carl Voigt, Thesis Advisor/Co-Advisor - Keywords:
- Material Reduction
MetalCasting
Foundry
Hydrogen Peroxide
Ozone
Ultrasonics
Sand Reclamation
Sustainable Manufacturing
Ultrasonic Cleaning - Abstract:
- The wet reclamation of a waste foundry green sand or baghouse dust has been demonstrated with applied ultrasonics, cavitation, settling (UCS) and advanced oxidants (AO). This technique reclaims sand, clay and coal from waste green sand or a bag house dust system while operating at near ambient temperature. The research presented herein evaluated a pilot-scale system that reclaimed waste green sand and a full-scale system that processed baghouse dust. This UCS process was developed to reclaim waste green sand, yet this same UCS system can be modified to serve as a replacement for blackwater clarifiers. AO treatments have been established as an effective way to diminish VOC emissions during mold cooling and shakeout. Pilot-scale trials were conducted using waste green sand that initially contained 7.9% methylene blue (MB) clay and 3.8% loss on ignition (LOI). The pilot scale reclamation unit generated recycled silica sand with only a small residual 0.4-1.0% LOI and 0.4-0.6% MB clay. This reclaimed sand can be used as make-up sand for a green sand system or as a replacement for new sand in the core room. Foundry cores made from 60% reclaimed sand, 40% new sand, and 1.1% phenolic urethane binder, yielded a 120 psi tensile strength, well above the 70-80 psi tensile strength that is often specified at this foundry. For the full-scale baghouse dust processing, a UCS system was integrated with the existing AO – Clearwater (AO-CW) system on Neenah Foundry’s Plant 3 sand return system. In this configuration, AO-treated baghouse dust experienced the UCS treatment; and the ultrasonics-cavitation was designed to remove the coating of carbonaceous pyrolytic residue from the surfaces of the clays and silica fines in this baghouse dust, and thus render the treated clays and organic matter for reuse in the green sand system. Over a one year start-up period, the baghouse dust concentration in the AO slurry was increased from 0.25 lbs dust/gal AO water to 0.75 lbs dust/gal. Pouring, cooling and shakeout VOC emissions were about a third as much as when only the AO - Clearwater system was operating without any added baghouse dust. With the UCS system operating in conjunction with AO, the bond consumption was 11% less than when AO was operating with no baghouse-UCS components. Also, as this UCS system stabilized, the proportion of MB clay, LOI and silica fines increased within the baghouse dust, while there was a decrease in amount of silica grains larger than #140 mesh that ended up in the bag house dust.