A case for utilization of clays to raw materials of outside wall at final disposal site of town waste matters and new treatment techniques for polluted soils

Abstract

Hazardous wastes contaminated with heavy metals, arenic and other toxic metals ware previously discharged to non lined landfills around final disposal sites of town waste disposals, in and around industry areas, and mining facilities. These wastes often provoke enviromental pollution to soils, groundwater, surface water, and other local geologic units which causes serious health risks. In order to protect from the enviromental pollutions, some kinds of clay mineral and natural zeolites with calcium compounds can be applied in two ways. One is mixing treatment of these materials to in situ remedy for toxic metals pollution within wastes. Ion-exchange property of zeolites and adsorption of clay minerals are elective in this treatment, which makes geochemically and mineral chemically stable state that reduces leaching of the toxic metals. The other is more physical and mechanical ways, that is a use of a mixture of clay minerals and natural zeolites with calcium compounds for liner materials at solid waste disposal site of which impermeable property as well as adsorption successfully shields migration of toxic metals from waste sites. This mixing technique is also utilized for new treatment processes in polluted sites by toxic metals, especially in soil of polluted by 6⁺ chromium. In this paper, we report typical results of laboratory experiment and some case studies of the remedation techniques by using clay minerals and natural zeolite with calcium compounds in industrial facility, solid disposal site, and disposal site of ore-processing residue and slag in smelting process, in Japan. These new techniques are introduced in international meetings, also, and they are reported in opportunity of International Symposium, held by 111th Committee on Development on the New Utilization of Minerals, Japan Society for the Promotion of Science (JSPS), October, 1998 in Toyko.