Calcination Behaviour of Guizhou Siderite Ore and its Amenability to Reduction by Waste Polymers

James Ransford Dankwah, Pramod Koshy, James Bradford Dankwah, Jessica Dankwah


Siderite (FeCO3) ore from Guizhou, China was heated for 40 mins in air in the absence and presence of high density polyethylene, HDPE, (sourced from waste pure water sachets) in a horizontal tube furnace and gas fired furnace. Solid reaction products were characterised using XRF, XRD and SEM/EDS analyses whilst gaseous products were analysed by a continuous infrared gas analyser. Composite pellets of the calcined product with HDPE were then heated in a gas fired furnace for 180 mins and the product was analysed by XRD and SEM/EDS analyses. The solid products after calcination were found to be highly magnetic with composition by XRF of 95.82 wt % Fe2O3, 2.95 wt % SiO2, 0.254 wt % Al2O3 and LOI of 0.40 wt % compared with an original XRF composition of 51.43 wt % Fe2O3, 10.80 wt % SiO2, 9.46 wt % Al2O3 and LOI of 24.75 wt %. Analysis by XRD revealed maghemite and magnetite as the predominant components of the calcined product from microwave irradiation and gas fired furnace, respectively, compared to FeCO3, SiO2 and Al2O3 for the original ore. Gas analysis by the IR gas analyser showed CO2 and CO as the major components in the off gas in the ratio of CO2/CO of approximately 2.0 when heated in the absence of the waste polymer. Heating in the presence of the waste polymer resulted in a drastic reduction in the composition of CO2 with a corresponding increase in the content of gaseous reductants (CO, CH4 and H2) in the off gas. Metallic iron and syngas (CO + H2) were observed to be the main solid and gaseous products after reduction of the calcined product.


Calcination; Siderite ore; Reduction; Waste polymers; Microwave irradiation

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