We consider elementary materials, such as steel and silicon, as recycling materials, and aim at the establishment of environmental friendly society by developing their production and recycling processes together with by-product treatment. Since reaction rates are large enough at high temperatures, evaluation of the reaction limit and its driving force is often an important key to the next steps. Physico chemical studies for Innovation of Iron- and Steel-making and Solar-Grade-Silicon Refining Processes and Enrichment of Waste Materials are being carried out in our laboratory with consideration on thermodynamics and high temperature physical properties.