Carbonization study of non coking coals and characterisation of their properties for application in sponge iron making

Abstract

In view of unavailability of costly coking coal (used for blast furnace route) in several countries including India, DRI route of iron making is getting momentum. At present India produces around 20MT sponge iron per annum, in which coal-based process have major contribution. Studies on the effect of different carbonization temperatures (400, 600,800, 900°C), chemical and physical properties (proximate analysis, reactivity, ash fusion temperatures and caking characteristics), and calorific or heating value of different coal samples, procured from different mines in India, were undertaken in the present project work for their judicial selection in Indian sponge iron plants. In the present project work, studies on chars prepared from Western coalfield limited (Madhya Pradesh), Southern east coalfield limited (Chhattisgarh), Mahanadi coalfield limited basundhara (Orissa) and Jharsuguda (belpahar), Kalinga and Lingaraja non coking coal at four different carbonization temperature (400, 600, 800,900°C) were characterized for their chemical (proximate and ultimate analysis), physical (apparent density and apparent porosity) properties, ash fusion temperature, calorific value, XRD, and reactivity. It is found that the fixed carbon content, ash content increases while volatile matter and calorific value reduced with increase in carbonization temperature. Reactivity of the coal chars towards CO2 was measured at these carbonization temperatures and it was investigated that with increase of carbonization temperature, the reactivity of chars towards CO2 was reduced. It was also investigated that Mahanadi coalfield limited (MCL) coal has maximum fixed carbon content and Jharsuguda mines coal has higher calorific value while SECL, korba char has highest fixed carbon content. Idea behind this is to found good coal and match its property according to its application in sponge iron plant.