Valimohiekkojen terminen elvytys osana teollista symbioosia

Probably the biggest problem for sand casting foundries has for long been the waste produced from disposable molds. Stricter environmental regulations make it harder to dispose of said waste, so a truly competitive foundry does no longer only make great products, but also concentrates on a sustainable casting process. While methods for repurposing waste foundry sand are still limited, the internal circulation of such sands proves significant possibilities. This thesis will focus on thermal reclamation of foundry sands in a special rotating drum oven in a central facility to serve several foundries. Thermal reclamation is a process for handling foundry sands in elevated temperatures to combust unwanted substances from reusable base sand. The literature review of this thesis focuses on the sand casting process, molding sands, reclamation techniques and the most common sand systems in Finland and how to best reclaim them. The practical part features presentation of the new reclamation plant process and the conducted test runs. The samples collected from each test run have been laboratory tested to assure proper sand quality. A part of this work also involves the idea of industrial symbiosis, as a central reclamation plant to serve several foundries is more difficult to fully understand with terms of traditional circular economy or sustainability. The results of this work showed that the reclamation of alkaline phenolic no-bake sands was excellent. Reclamation of green sands didn’t provide satisfactory results as expected and the reclamation of furan no-bake sands provided mixed results as the raw material was imperfect to begin with. The most important result of this work is still the successful initiation of a centralized thermal reclamation plant, with the ability to reclaim sands from several Finnish foundries. With this all of industrial symbiosis, circular economy and sustainability made progress in not only Finland, since the future development of this plant provides even more opportunities and a possibility to spread the ideas around the world.