Process for Complete Utilisation of Olivine Constituents

A process for utilisation of olivine, the process comprising the following steps:

• a) reacting olivine with up to 36 weight % HCl in a reactor, providing MgCl2 brine, preferably removing impurities,
• b) separating silica from the MgCl2 brine and further treating the silica according to its applications,
• c) removing more impurity particles which together with impurities from the above reacting step, a) can be utilised as a sand product,
• d) oxidation of the brine by air and KMnO4 or other oxidants and correction of the pH applying preferably alkaline substance(s),
• e) separating the brine and precipitated Fe and Ni compounds by means of adding flocculant prior to a suitable solid/liquid separation equipment,
• f) further purifying the MgCl2 brine using trivalent Fe substance, thereby adjusting Fe/Ni ratio to be preferably higher than 120, adding preferably alkaline substance(s) and/or other chemicals to adjust the brine composition and pH, and separating the impurities by a suitable solid/liquid separation equipment,
• g) adjusting the pH using HCl to produce a purified MgCl2 brine applicable for Mg production,
• h) leaching of the Fe and Ni precipitate form step e) using an appropriate acid, at a suitable temperature, to separate the Ni from Fe,
• i) mixing the resulting Fe solids from the previous step h) with the filter cake from the polishing step, f) followed by forming a Fe oxide product applicable for instance as raw material for the ferro-silicium industry,
• j) adding alkalines to the Ni leaching extract from step h) adjusting the pH, and after separation of the precipitate, preferably returning the brine to the oxidation tank, step d)
• k) and finally re-dissolving the Ni solid compound, using an appropriate acid, and precipitate the Ni product as carbonate.