Application of remedy studies to the development of a soil washing pilot plant that uses mineral processing technology: a practical experience

Soil washing employing mineral processing technology to treat radionuclide- contaminated soils has been examined as a remedy alternative to the exclusi ve excavation, transportation, and disposal of the soil. Successful applica tion depends on a thorough remedy study, employing a systematic tiered appr oach that is efficient, self-limiting, and cost effective. The study includ es: (1) site and soil characterization to determine the basic mineral and p hysical properties of both the soil and contaminants and to identify their relative associations; (2) treatment studies to evaluate the performance of process units for contaminant separation; (3) conceptual process design to develop a treatment pilot plant; and (4) engineering design to construct, test, and optimize the actual full-scale plant. A pilot plant using soil wa shing technology for the treatment of radium-contaminated soil was develope d, tested, and demonstrated. The plant used particle-size separation to pro duced a remediated product that represented approximately 50% of the contam inated soil. Subsequently, it was modified for more effective performance a nd application to soil with alternate characteristics; it awaits further te sting. The economic analysis of soil washing using the pilot plant as a mod el indicates that a remedy plan based on mineral processing technology is v ery competitive with the traditional alternative employing excavation, tran sportation, and disposal exclusively, even when disposal costs are modest o r when recovery of remediated soil during treatment is low. This paper revi ews the tiered approach as it applies to mineral processing technology to t reat radionuclide-contaminated soils and a pilot plant developed to test th e soil washing process. (C) 1999 Elsevier Science B.V. All rights reserved.