Production of magnesium hydroxide from magnesium silicate for the purpose of CO 2 mineralisation - Part 1: Application to Finnish serpentinite

Experience Nduagu, Thomas Björklöf, Johan Fagerlund, Johan Wärn, Hans Geerlings, Ron Zevenhoven*

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    58 Citations (Scopus)


    Carbonation of abundantly available magnesium silicates such as serpentinites could be an attractive route to capture and store CO 2. In this paper we describe a novel route to produce magnesium hydroxide, Mg(OH) 2, from Finnish serpentinite. The resulting Mg(OH) 2 is much more reactive towards CO 2 than the parent serpentinite. The process route of producing Mg(OH) 2 as reported here involves a staged process of Mg extraction using a moderately high temperature solid/solid reaction of serpentinite and ammonium sulphate (AS) salt followed by precipitation of Mg(OH) 2 using aqueous ammonia. Tests at 400-550°C showed promising results. An optimum range of reaction conditions for the extraction stage (Mg extraction) and precipitation stages (production of valuable products) of the process was also identified. The valuable solid products refer to Fe-containing compound (dark brown solid, exhibiting the properties of FeOOH) and Mg(OH) 2 (white precipitate), both precipitated in an aqueous solution with 25% (v/v) ammonia at pH 8-9 and 11-12, respectively. In some cases all Mg extracted from serpentinite was converted to magnesium Mg(OH) 2 with very small volumes of ammonia solution added. Apart from the relatively cheap AS salt reagent, the prospect of recovery and use of by-products of the process: ammonia gas, FeOOH, and AS salt presents significant benefits.

    Original languageEnglish
    Pages (from-to)75-86
    Number of pages12
    JournalMinerals Engineering
    Publication statusPublished - Apr 2012
    MoE publication typeA1 Journal article-refereed


    • Ammonium sulphate
    • Magnesium extraction
    • Magnesium hydroxide
    • Mineral carbonation
    • Precipitation
    • Serpentinite


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