11 systems and apparatus for the treatment of materials containing reclaimable chemical and other compounds and elements and/or for neutralizing or rendering harmless material containing hazardous substances, for use in the metal industry; namely, chemical leaching apparatus for extracting reclaimable chemicals, compounds and elements from particulate materials, furnaces for burning and calcining particulate materials, hot gas/solids contacting apparatus, fluidized bed furnaces, gas/solid separation apparatus, and cyclone bag houses