United States - 2013
Recycled Casting Materials Go to Bottom Line Rather than Landfill
Recycling spent ceramic slurry and shells from the manufacture of multiple alloy castings is eliminating thousands of metric tons of material from landfills and creating a new revenue stream for Alcoa.
The company manufactures a variety of castings used primarily in the aerospace and industrial gas turbine industries. Because these parts must meet strict tolerance, quality, and durability requirements, each is created using an individual wax form. This form is dipped in successive ceramic slurries that harden to form a ceramic mold into which molten metal is poured. Once the metal solidifies, the ceramic mold is broken and the metal part is removed for further finishing.
Historically, much of the used mold material in both liquid form (spent slurry) and solid form (spent shell) was transported to a landfill by a waste vendor. In January 2011, five U.S. Alcoa locations began exploring opportunities to develop downstream markets for spent ceramic slurry and shell.
Today, a portion of these materials is sold into the steel industry for use in manufacturing processes. Where it is not geographically or economically feasible to sell the solid materials, they are used as roadbed base material.
In 2012, Alcoa avoided landfilling more than 1,000 metric tons of spent slurry and shell, generated a positive revenue stream from sales to the steel industry, and reduced its waste management costs. Those numbers are expected to increase in 2013, with more than 2,200 metric tons being removed from the waste stream.
Alcoa is working to recycle several other ceramic waste streams, which has the potential to eliminate an additional 7,000 metric tons of material from the landfill annually and redirect it into beneficial uses.