In its latest round of national emission standards for hazardous air pollutants (NESHAP), Environmental Protection Agency proposes lower limits for mercury and non-mercury metals, plus hydrogen and chlorine gases from clay brick tunnel (continuous curing) kilns, coupled with target startup and shutdown periods. EPA also envisions work practice standards for more specialized periodic kilns, which are heated up to 2,000°F, then left to cool for several days. Tunnel kilns are typically fired by natural gas or sawdust; periodic kilns, coal.
EPA published “NESHAP for Brick and Structural Clay Products Manufacturing (BSCP)” in the Federal Register, noting that new kiln emissions thresholds and other requirements will see brick producers incur an estimated $55 million in capital costs, plus $18.4 million in annual compliance costs—against $24 million to $99 million in net public benefits. A formal announcement of the proposed NESHAP for BSCP will trigger a 45-day public comment period.
Beyond lower emissions, the EPA sees initial and five-year performance testing for the regulated pollutants, continuous parameter monitoring, and daily visible emissions checks. The BSCP Manufacturing category includes operations molding clay brick (face, structural, paver and other units), dimensional products and pipe, plus extruded floor, roof and wall tile.
NESHAP for BSCP surfaces amid a more costly undertaking for U.S. portland cement producers; facing a September 2016 compliance deadline, they are equipping mills to meet EPA’s lower thresholds for mercury and hydrochloric gas emissions, plus particulate matter. The current BSCP proposal follows EPA’s 2003 NESHAP for brick kiln operation that was vacated in federal court four years later.