Recovery of Iron Values from Iron Ore Slimes using Reagents

Mining wastes include waste generated during the extraction, beneficiation or processing of
minerals like iron ore fines, slimes and tailings. Approximately 10–20% of the raw material is
discarded as slimes in to slime ponds/tailing dams. Recovery of iron values from slimes result
in economic benefit by utilization of waste as a resource and minimizes the threat to the
environment. The iron ore slime is generally considered as waste due to its ultrafine nature
and its processing limitations. The chemical analysis of the present iron ore slime is 34.75%
Fe with 21.94% SiO 2 , and 14.4% Al 2 O 3 . This research work presents the route to size
enlargement of slime using reagents and enrichment of iron values by various beneficiation
techniques for the effective utilization of iron ore slime. Screen analysis revealed that 90% of
the particles are smaller than 80.15 µm. In the present investigation, the recovery of lost iron
values from iron ore slime waste was attempted using different beneficiation techniques like
Enhanced gravity separation (EGS) Falcon concentrator, Gravity separation by Mineral
separator and Vanner, and selective flocculation after treatment with various reagents.
Mineral separator generated a concentrate assaying 46.3% Fe with 56.2% recovery using
polyacrylamide flocculant at 90 sec collection time and similarly Vanner produced a
concentrate assaying 54.5% Fe with a recovery of 41.6% using CMC. From selective
flocculation studies, a concentrate assaying 45.3% Fe with 42.1 yield % was obtained using
modified corn starch at a settling time of 5 min, as starch facilitates the selective adsorption
on iron particles, which in turn leads to enhancement in selectivity and recovery.