Exclusion as it applied to mineral processing wastes to include only "large volume, low hazard" wastes.
This rulemaking process was completed with the publication of final rules on September 1, 1989 (54 FR 36592) and January 23, 1990 (55 FR 2322) which defined the scope of the exclusion.
In July 1990, EPA completed the required Report to Congress on Mineral Processing Waste. This report studied 20 specific mineral processing wastes based on volume and hazard criteria.
EPA did not complete the regulatory determination within the six month statutory deadline. As a result, the Environmental Defense Fund filed a new RCRA citizen's suit.
EPA satisfied the decree by publishing a final rule and regulatory determination on June 13, 1991. This rule exempted the 20 mineral processing wastes.
The "special 20" mineral processing wastes, as listed at 40 CFR 261.4(b)(7), are:
Slag from primary copper processing
Slag from primary lead processing
Red and brown muds from bauxite refining
Phosphogypsum from phosphoric acid production
Slag from elemental phosphorus production
Gasifier ash from coal gasification
Process wastewater from coal gasification
Calcium sulfate wastewater treatment plant sludge from primary copper processing
Slag tailings from primary copper processing
Fluorogypsum from hydrofluoric acid production
Process wastewater from hydrofluoric acid production
Air pollution control dust/ sludge from iron blast furnaces
Iron blast furnace slag
Treated residue from roasting/ leaching of chrome ore
Process wastewater from primary magnesium processing by the anhydrous process
Process wastewater from phosphoric acid production
Basic oxygen furnace and open hearth furnace air pollution control dust/sludge from carbon steel production
Chloride process waste solids from titanium tetrachloride production
Slag from primary zinc processing
These 20 mineral processing waste streams are exempt from regulation under RCRA Subtitle C