NOVELTY - Re-use of silicon powder recovered from band saws and other silicon mechanical operations as feed material to prepare crucible charges for casting polycrystalline-multicrystalline silicon ingots for photovoltaic applications involves silicon powder recovery from band/wire saws, grinding by filtration and treatment of exhausted slurries; conditioning in non-oxidizing environment; treatment with hydrofluoric acid, hydrochloric acid and/or hydrofluoric acid and hydrogen peroxide; second treatment with hydrofluoric acid; preparation for compaction step; and compaction of silicon powder.    USE - For re-use of silicon powder recovered from band saws and other silicon mechanical operations as feed material to prepare crucible charges for casting polycrystalline-multicrystalline silicon ingots for photovoltaic applications (claimed) e.g. solar cells and in microelectronic industry.    ADVANTAGE - The process provides a new or alternative source of solar grade silicon by the recovery and re-use of silicon waste powder that is generated as kerf (micron-size silicon powder) at mechanical operations in photovoltaic and electronic industries. Moreover, the economical and environmental benign process provides effective separation of silicon kerf from the waste water of band saws and grinders or from cakes or sludges coming from exhausted slurries from wire saws operations; avoids the oxidation and hydrogen development of the kerf during operations; provides efficient removal of metal impurities at the level required by photovoltaic industry; and removes serious difficulties when melting the recovered kerf because of the small size of the particles and their low density as well as their surface oxidation conditions.    DETAILED DESCRIPTION - Process for re-use of silicon powder recovered from band saws and other silicon mechanical operations, as feed material to prepare the crucible charges for casting of polycrystalline-multicrystalline silicon ingots usable for photovoltaic applications involves: a) silicon powder recovery from band saws/wire saws, grinding operations by filtration and treatment of the exhausted slurries; b) conditioning in non-oxidizing environment; c) treatment with hydrofluoric acid; d) treatment with hydrochloric acid and/or hydrofluoric acid and hydrogen peroxide; e) second treatment with hydrofluoric acid; f) preparation for the compaction step; and g) compaction of the silicon powder.