Is it a liability or a resource? That’s the crux of the revolving discussion about sand in metalcasting operations, and despite the fact that this problem (or opportunity) is so widely recognized — different foundries must approach it differently because the job of handling foundry sand manifests itself differently from one foundry to the next.

Now, one company aims to reframe the matter around a new process technology, and if it succeeds it will be because it addresses both versions of the foundry sand conundrum — conserving the resource and reducing the liability. In the course of this outcome, it will establish a new, standard process function for green sand foundries.

Renotek International, Sherbrooke, Quebec, owns the North American license for the patented Renofont process, which it describes as a “bentonite and sand reclamation system” for green sand that conserves the value of the mold and core makeup materials, and reduces the significant responsibility for disposing of the otherwise spent sand.

Green sand is a general term for the various, specific combinations that foundries use to form molds (and cores), in order to hold a shape that will contain molten metal well enough to resist thermal shock effectively as the metal solidifies. The formulation of the green sand is critical to other aspects of the process too, like the surface finish of the cast product, and the mold’s ability to absorb gas emitted by the cooling metal. In general, green sand consists of 75-85% sand (silica, chromite, zircon, olivine, or graphite), 5-11% bentonite (clay), 2-4% water, 3-5% other inert material, and 0-1% carbon (e.g., anthracite, or “sea coal.”)

The specific formulations are determined by many factors, including the metal that is being poured, as well as the cost and availability of different sand types and the expense and/or difficulty of handling the spent sand. The cost of environmental compliance for handling (e.g., landfilling) the sand is part of this consideration.

Renotek aims to overturn all these calculations with its technology, which it emphasizes uses only water and very little energy to clean the spent sand, recovering both bentonite and sea coal. Pierre Boucher, director of finance and sales for Renotek, indicated the process was patented first in Europe, later in North America, and that the company has only recently started its marketing effort to foundries in the U.S. and Canada.