Process for complete utilisation of olivine constituents

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

• a) reacting olivine with up to 36 weight % HCl in a reactor, providing MgCl2 brine, 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 an oxidant other than KMnO4 and correction of the pH,
• 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 higher than 120, adding 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 to form a filter cake,
• g) adjusting the pH of the liquid resulting from step f) using HCl to produce purified MgCl2 brine applicable for Mg production,
• h) leaching of the Fe and Ni precipitate from step e) using an appropriate acid, at a suitable temperature, to separate a Ni leaching extract from Fe solids,
• i) mixing the resulting Fe solids from the previous step h) with the filter cake from the purifying step f) followed by forming a Fe oxide product,
• j) adding alkalines to the Ni leaching extract from step h) adjusting the pH, and after separation of a Ni solid compound, returning the brine to step d),
• k) and finally re-dissolving the Ni solid compound, using an appropriate acid, and precipitate a Ni product as carbonate.