Slag Solution

Enter Serious Materials and its EcoRock drywall. EcoRock is not all-natural drywall—–that would be called “wood”—–but it is an attempt to do away with wasteful gypsum drywall manufacturing by taking the leftovers of other manufacturing processes and turning them into something useful.

an introduction to manufacturing gear grid
Some historians say that the first factory was the Venetian Arsenal, which employed thousands of workers in the 15th century and could build 30 ships in 10 days. Samuel Slater (father of the American industrial revolution) got his start by memorizing, then stealing, designs for Richard Arkwright’s yarn-spinning machine.

The “rock” in EcoRock is primarily slag, a mineral-like solution of silicates and oxides that is left over at the bottom of the furnace during glass or steel manufacturing. (Slag is to natural rock what Lady Gaga is to Joan Jett.) In the old days of cheap manufacturing, furnace owners used to throw away slag, but in the past few decades slag has gained some respect as an aggregate in road building, and now as drywall.

Of course, as the leavings of a gas-fired blast furnace, slag itself is hardly carbon neutral. For EcoRock, since the slag already exists, and the carbon to make it has already been spent, we might as well benefit from the result.

Unlike freshly mined gypsum, furnace slag is already dehydrated. At the EcoRock factory, it is made into slurry with water and a few proprietary materials, and then pressed between sheets of fiberglass—–not too different from regular drywall manufacturing.

The next step is critical: In CEO Kevin Surace’s words, EcoRock “cooks itself and dries itself.” Though he won’t say anything more about that process, Surace drops hints that the mixture of materials results in a chemical reaction that gives off enough heat to drive the water out and bind the slag particles together. Because this heat comes from within the material, there’s no need to run the boards through a second drying station, which prevents even more CO2 from being released.

Serious Materials runs EcoRock on a cradle-to-cradle manufacturing system, claiming that every bit of its drywall can be recycled. Surace set a goal for his company to eliminate one billion tons of anthropogenic CO2 from the atmosphere in 12 years, primarily by not putting it there in the first place.

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