Ore grinding energy minimisation by thermal treatment

Abstract

Grinding of iron ore is an essential step to utilise ore fines for pelletisation needed for DRI units. While preparing iron ore pellets for DRI production, the iron ore needs extensive grinding which is highly energy consuming step causing the process to become non-viable in some cases. In the present paper an attempt has been made to evaluate grinding performance of thermally treated ore compared to normal ore grinding. Such thermal pre-treatment has been found to reduce the energy requirement with lower consumption rate of grinding media. It has been observed that by applying thermal shock the ore is rendered weak with improved grindability. The stresses generated due to thermal treatment may extend existing micro- cracks in the ore and in some cases it may even nucleate fresh cracks. Experimental studies carried out on thermally treated hematite ore reveals that the heating to 400°C followed by water quenching can cause a reduction of 45 per cent in grinding energy. The paper gives the details of the experiment and the results.