Separation response of iron ores during gravity concentration

Abstract

Two types of iron ores namely soft laminated ore and goethitic-lateritic ore is studied in details from Jilling-Langalota deposit, Singhbhum-N, Orissa Craton, Eastern India. The soft laminated iron ore contained relatively high hematite as compared to Goethitic-lateric ore which contained goethite in large quantity. Beneficiation of iron ores by gravity separation method is studied. The ore samples are beneficiated with a view to produce sinter quality concentrate. The soft laminated ore contained 61.29% total iron, 5.04% silica and 4.29% alumina while the Goethitic-lateritic ore contained 53.34% total iron, 7.4% silica and 5.49% alumina. Liberation analysis of different size fraction suggested that grain size reduction lower than 150 mm size would be necessary to achieve sufficient liberation of iron ore minerals from the associated gangue (kaolinite and gibbsite). However, the percentage of interlocking is higher in case of Goethitic-lateritic ore compared to soft laminated ore. Considering the characterisation data, the soft laminated ore is ground separately to three size fractions namely 300 mm, 250 mm and 150 mm sizes, while the goethitic ore is ground to 150 mm size and subjected to flowing film concentration in Wilfley Table. The grade of the soft laminated ore is improved from 61% Fe to 66% Fe while for the Goethitic-lateritic ore the Fe content is enriched from 53% to 64% in simple one-stage concentration operation. The nature of the ore mineral plays important role in the separation process. Due to enrichment of goethite and friable nature of Goethitic-lateritic ore significant amount of Fe is lost during the process as compared to soft laminated ore.