Foundry sand is the main foundry residue, since it is used for making all the molds for the cast parts. Finding a solution for the reutilization of spent sand has been the greatest challenge for TUPY. Discarded sand from the core making process is not a problem for TUPY anymore. The company counts on its own regenerating systems in its two manufacturing plants in Joinville and Mauá and practically all the sand is reused.
The greatest volume, however, consists of molding sand and that is classified by ABNT, the Brazilian Technical Standards Association, as non inert Class II residue, and until very recently, had as its one and only destination the landfills. That does not happen in European countries and in the United States where that kind of sand is reused for several purposes.
Each State environmental agency has the obligation to propose laws about the issue. Convincing them that molding sand is not dangerous has required a lot of studies and evidence from the Brazilian foundries. In that area, TUPY is, certainly, the company that has brought more contributions to the discussions and offered the most subsidies.
With the approval, in 2008, of a resolution of the Santa Catarina State Environment Council authorizing the use of foundry sand in the making of asphalt mixes and non-structural concrete artifacts, a new front has been opened by TUPY. As an experiment, the company opened a paver factory. Pavers are used for paving sidewalks and the factory has been producing lots that are being donated to public constructions in the city of Joinville. The purpose is to show the construction market that the reutilization is viable, avoiding, that way, the use of new sand, a natural resource, and contributing to reduce the volume of the sand taken to landfills.
The amount of sand used in the manufacture of pavers is still too small, and, therefore, TUPY is leading other experimental projects in the state of Santa Catarina, such as the use of the sand for building bases and sub-bases for roads and as a support sewage pipelines. Still, in the effort to prove the non-hazardousness of the residue, the company developed, in a partnership with EPAGRI – an agriculture and cattle-raising and rural extension research company – an experiment in which lettuce and carrots were cultivated in soil to which the discarded sand was added. The results showed that there was no damage to the plants.