Slag Blocks

Smelters separate ore into metal and slag. Slag from copper and nickel production is mostly dumped on slag heaps, where mining companies pay to manage the risk of heavy metals leaching into water. We are researching how to use it as a building material instead.

The idea came from 18th-century slag buildings that still stand, such as those beside the copper mine in Falun, Sweden, now a UNESCO World Heritage Site. Molten slag can be poured into large forms. Big blocks have far less surface for leaching, and they anneal into stone as they cool, with no added energy. The blocks look like granite or basalt and can be cut to transportable sizes, then squared, honed or polished for compression structures or as surfaces on steel, wood or concrete buildings.

With Vale in Sudbury, we have refined the casting process several times and produced our first consolidated large block. Next come material testing of the cast cube, a small first use of a few cubes, and structural testing toward a single-storey pavilion. Slag is also the counterweight in our Formid seat.