Beneficiation of banded hematite quartzite from meghatuburu mine, eastern India

Abstract

The present paper describes the beneficiation of Banded Hematite-Quartzite (BHQ) from Meghatuburu mine, India. In general, BHQ ores contain around 30–38% Fe, 45–50% SiO2 and 1–2% Al2O3 and hence can hardly be used in steel making. However, if they are beneficiated and enriched to around 64% Fe, which is possible only in fine size range, they can be utilized in a pelletization plant. The feed sample assayed 37.52% Fe, 42.23% silica and 0.82% alumina. Microscopic studies reveal that the silica bands contain some hematite and the hematite bands are also not free from silica. It was observed from the liberation data that reasonable degree of liberation is achieved only below 150 micron size. Beneficiation studies using various unit operations such as hydrocyclone, falcon concentrator, Low Intensity Magnetic Separation (LIMS), Wet High Intensity Magnetic Separation (WHIMS) and flotation etc. were carried out to develop a suitable process flowsheet as a step towards the up-gradation of iron values and to reduce the gangue content. The separation techniques were selected based on particle size and properties for effective separation. The developed process flowsheet gives the desired enrichment of the BHQ ore at reasonable yield. Two-stage classification in a hydrocyclone yields a coarse product with 47% Fe with a yield of 75% was obtained. The hydrocyclone overflow contained only about 28% Fe and hence, was rejected. The cyclone underflow was treated in falcon concentrator and a product with 53% Fe was obtained. The falcon underflow was treated in LIMS. The non-magnetic stream from LIMS was treated in WHIMS and a concentrate of about 57.3% Fe with a yield of 32.2% was obtained. Reverse flotation of the WHIMS concentrate was performed using starch as depressant for iron minerals, calcium chloride to activate silica, cationic collector dodecyl amine hydrochloride and MIBC as frother at a pH of 10.5–11.0. Final concentrate of nearly 64% Fe with a yield of 28% was achieved using the developed flowsheet.