Flotation of fine particles and organometallic precipitate in column. Physico-chemistry, modeling and extrapolations

A methodology was established to apply flotation column for flotation of fine mineral particles and precipitate or organometallic complexes. The main parameter that governs aggregation phenomenons and flocs stability is the energy dissipation during mechanic stirring or during rising of air bubbles in the column. This system is applied to mineral particles (cassiterite) and to molybdenum and chromium organometallic precipitates in sulfuric medium. The aggregation mechanism of molybdenum precipitate is interpreted from its fractal properties by means of laser sizer analyses and image treatment. The flotation kinetic depends on bubbles diameter and solid size. At pilot scale, bubbles generators as Microcel, Flotaire and Imox were used for organometallic precipitates flotation. For fine cassiterite particles an original generator was employed. Results show that flotation columns are suitable as well for fines particles flotation as for industrial wastes treatment, notably with a new method for complex ionic chromium flotation. A model for column design allows to calculate their size and their number. The model validity has been confirmed by pilot tests (in France and Russia) and also in an industrial application on cassiterite with a 2 meters diameter column (in Russia). (author)