Process for production of precipitated silica from olivine

A process for the production of precipitated silica from olivine,

• comprising the following steps:
• providing olivine particles with a particle size below 1 mm in diameter,
• mixing the olivine particles and water to form an olivine/water slurry,
• mixing the olivine/water slurry with hydrochloric acid (HCI), at a concentration at 18 wt % or above, and at a temperature between 50-130°C, to form an olivine/acid slurry, and reacting the olivine/acid slurry for a period of time between 20-360 minutes to form a reacted mixture, wherein the reacted mixture contains coarse mineral impurities,
• removing the coarse mineral impurities (sand product) from the reacted mixture to obtain a mother solution comprisingprecipitated silica,
• separating the precipitated silica from the mother solution,
• mechanically treating the separated precipitated silica and optionally some water to obtain a slurry,
• preparing a low viscosity slurry by adding sodium aluminate or another aluminate, to 100-6000 p.p.m., and adjusting the pH to a value between 4-9,
• ageing the low viscosity slurry at a temperature between 50-150°C. according to product requirements,
• dispersing the aged silica slurry, wherein the slurry contains fine mineral impurities,
• removing the fine mineral impurities (sand product) from the slurry to obtain a substantially purified slurry, and
• drying the silica.