Pozzolanic, Amorphous Silica Produced from the Mineral Olivine

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Title: Pozzolanic, Amorphous Silica Produced from the Mineral Olivine

Author(s): H. Justnes and T. Ostnor

Publication: Special Publication

Volume: 199

Issue:

Appears on pages(s): 769-782

Keywords: calcium hydroxide; camorphous silica; olivine; pozzolan;

Date: 6/1/2001

Abstract:
Amorphous silica with high whiteness decomposing the basic mineral olivine, solution of magnesium and ferrous salt washing and filtering or decanting. And (Mg s and surface can be produced by simply Fe)SiO2 in any acid. The result is a silica slurry that can be purified by Such silica has been produced by treating an olivine mineral residue, a by-product of nickel ore recovery, by hydrochloric acid. The free flowing silica residue, after drying at 105C, is proven to have pozzolanic activity (consumption of calcium hydroxide) by thermal analysis (DTA/TG) and by strength measurements of mortars where cement is replaced with silica. The reactivity and strength gain was comparable to conventional silica fume obtained from ferrosilicon plants. The abundant mineral olivine can be a valuable source of amorphous silica for concrete technology, while the waste product lye could be used as a CO2 free magnesium chloride source for magnesium metal production, after purification. The process could also use waste acids, from paper pulp industry.