Batch scale study on magnetizing roasting of low-grade iron ore tailings using fluidized bed roaster

Abstract

The present steel production of India is 111.24 MTPA in January 2019 as per the Ministry of Steel, Govt. of India. The demand for steel production is increasing day by day. Depleting the high-grade iron ore resources compels steel industries to utilize the low/lean grade iron ore to meet future demand. However, there is no technology available that can directly use these low-grade iron ore. Further, these iron ores are dumped in different mine heads and slime ponds as waste creating environmental and societal problems. Therefore, it is need of the hour to develop suitable scientific methods where these low and lean grade iron ore can be effectively utilized. Magnetizing roasting of this low and lean-grade iron-ore followed by low-intensity magnetic separation can produce high-grade magnetite. The present study focused on the reduction roasting of a tailing iron ore sample having 47.47 %Fe in a batch-type fluidized bed roaster. The roasting of the sample was conducted at a temperature of 1000 °C and varying residence time from 2 to 10 min. Non-coking coal was employed as a reductant for the reduction reaction. The fluidization velocity was maintained at 1.5–1.7 times the minimum fluidization velocity. Then, the roasted sample was subjected to LIMS to obtain a high-grade magnetite concentrate. The study reveals that 61.1-grade iron ore can be obtained at 2 min residence time with 48.4% and 62.5% yield and recovery.