STP1062

    The Impact of Particle Size on TCLP Extraction of Cement-Stabilized Metallic Wastes

    Published: Jan 1990


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    Abstract

    EPA has introduced the Toxicity Characteristic Leaching Procedure (TCLP) in rulemakings associated with the Hazardous and Solid Waste Amendments of 1984. Limited ruggedness testing has evaluated the method's sensitivity to some test variables but has not addressed the effect of waste particle size. The TCLP method specifies a maximum particle size (9.5 mm sieve opening) and sets no lower limit.

    To evaluate the effect of particle size, the authors tested an arsenic waste and a chromium waste, each stabilized with Portland cement. Five discrete particle size fractions ranging from 9.5 mm down to 0.5 mm were extracted by the TCLP procedure. For both wastes, it was found that the metals leached more readily from the larger particle fractions. Furthermore, the pH of the extraction fluid during the first 2 hours of the extraction stayed acidic for the large particles while for the smaller particles, the pH quickly became basic. Final extract pH was lower for the larger particles than for the smaller particles.

    The results of this work indicate that particle size has a strong influence on TCLP extraction results for the tested wastes. This suggests that the particle size variable needs tighter controls than presently specified in the TCLP method to ensure reproducible results for at least some wastes.

    Keywords:

    TCLP extraction, particle size, stabilized wastes, metallic wastes, metals leaching, cement-stabilized metallic wastes, Toxicity Characteristic Leaching Procedure


    Author Information:

    Prange, NE
    Senior Environmental SpecialistEnvironmental Technician, Monsanto Company, St. Louis,

    Garvey, WF
    Senior Environmental SpecialistEnvironmental Technician, Monsanto Company, St. Louis,


    Paper ID: STP18965S

    Committee/Subcommittee: D34.02

    DOI: 10.1520/STP18965S


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