Chromium containing waste materials may typically be residual chromium wastes resulting from the processing of ferrous chromite ore or soils contaminated as the consequence of disposal practices associated with the disposal of such process wastes. Chromium ore processing wastes can contain up to ten percent by weight chromium. Soils contaminated by process wastes can contain chromium in amounts exceeding 1000 milligrams per kilogram (0.1 percent by weight). Such chromium ore processing wastes and chromium contaminated soils are recognized as a health hazard. Thus, there is a need for improved processes for the removal of chromium from ore processing wastes and contaminated soils so as to reduce the chromium to environmentally acceptable levels. Such improved process should also provide the secondary beneficial result of recovering the removed chromium in industrially useful forms. Processes for the removal of chromium from chromium containing waste material should themselves be capable of operation in an environmentally safe manner.
USPTO Backgrounds
USPTO Backgrounds