Preparation and characterisation of porous haematite through thermal decomposition of a goethite concentrate.

The preparation was investigated of porous haematite for use as an adsorbent for the treatment of wastewater containing heavy metals. The process involved the thermal decomposition of a goethite concentrate obtained from an iron ore concentration plant in Guangdong, China. The concentrate was calcined in a muffle furnace and the effects of temperature and residence tine were investigated. At a calcining temperature of 200 degrees C no decomposition occurred, but at 300 degrees C only haematite was identified and no composition changes were observed at higher temperatures. The haematite consisted mainly of micropores, which significantly increased the specific surface area and pore volume. The mechanism may involve the dehydration and dehydroxylation of goethite during the thermal treatment. At higher temperatures sintering of the haematite may occur, resulting in the merging of micro- and meso-pores and reducing the specific surface area. The mes-pores decreased with increasing residence time, but the average dimensions of the micropores and meso-pores exhibited no apparent changes.
The preparation was investigated of porous haematite for use as an adsorbent for the treatment of wastewater containing heavy metals. The process involved the thermal decomposition of a goethite concentrate obtained from an iron ore concentration plant in Guangdong, China. The concentrate was calcined in a muffle furnace and the effects of temperature and residence tine were investigated. At a calcining temperature of 200 degrees C no decomposition occurred, but at 300 degrees C only haematite was identified and no composition changes were observed at higher temperatures. The haematite consisted mainly of micropores, which significantly increased the specific surface area and pore volume. The mechanism may involve the dehydration and dehydroxylation of goethite during the thermal treatment. At higher temperatures sintering of the haematite may occur, resulting in the merging of micro- and meso-pores and reducing the specific surface area. The mes-pores decreased with increasing residence time, but the average dimensions of the micropores and meso-pores exhibited no apparent changes.