Production of low-carbon amorphous precipitated silica and hydrated magnesium carbonate from olivine

A novel process is reported that produces amorphous silica and nesquehonite (MgCO3.3H2O) from the magnesium silicate mineral olivine ((Mg,Fe)2.SiO4). The amorphous silica formed is a supplementary cementitious material (SCM) for use in concrete. The formation of nesquehonite sequesters carbon and means that the overall process is carbon negative. Nesquehonite can also be used to form low-carbon construction products such as bricks, blocks, and boards. This paper reports on key process optimisation studies. The potential for amorphous precipitated silica derived from olivine to produce carbon-negative concrete is discussed.