Methods of decontaminating mercury-containing soils

摘要

Soil including sand and clays contaminated with elemental mercury are decontaminated by forming slurries with anhydrous liquid ammonia. An ammoniacal liquid, such as anhydrous liquid ammonia facilitates decontamination by breaking up soil into fine slurries for releasing droplets of mercury metal. The high density of the mercury metal permits precipitation with larger soil particles and for recovery from soil particulates. Contaminated soils having mixed wastes comprising metallic mercury with organic compounds like PCBs are decontaminated first by slurring with anhydrous liquid ammonia to release droplets of mercury for coalescing and recovery. Solvated electrons are formed in the slurry in-situ by treating the slurry with an alkali metal or alkaline earth metal to reduce or degrade toxic organic compounds to more environmentally benign substances. Mixed waste comprising elemental mercury and nuclear waste, such as radionuclides like plutonium and uranium in the fines of soil and clay can also be concentrated to yield residual soil products which are sufficiently free of contaminants to allow reclamation. Economics are improved over aqueous systems since ammonia can be recovered and recycled. By concentrating nuclear wastes in soil fines space requirements ordinarily needed for storage of untreated soil and handling costs can be significantly reduced.