Abstract
Some physical and chemical properties of ferric oxide (a-Fe2O3, hematite) produced by spray roasting of HCl pickling liquor were examined in order to elucidate following subjects.
(1) The effect of FeCl2 concentration in sprayed liquor and roasting temperature on mean particle size of fine hematite.
(2) Forming process of hematite granules (agglomerated particles), thermal decomposition process from FeCl2 to iron oxide and dechlorination process of hematite.
The results are summarized as follows:
(1) The mean particle size of hematite is almost determined by FeCl2 concentration and roasting temperature.
(2) The thermal decomposition of FeCl2 is an exothermal reaction. When the roasting temperature is below the melting point of FeCl2, the reaction product mainly consists of a-Fe2O3. At higher temperatures, the Fe3O4 content increases.
(3) The weight change of hematite by firing in air coincides with the sum of the decrement of H2O and chlorides through desorption and decomposition and the increment of combined oxygen through oxidation of Fe (II) to Fe (III). The desorption of H2O and HCl on hematite is completed at about 250°C. Other chlorides in hematite are recognized as FeCl2 and FeCl3.
