Hrushikesh Sahoo

Optimization of flotation variables for the recovery of hematite particles from BHQ ore

The technology for beneficiation of banded iron ores containing low iron value is a challenging task due to increasing demand of quality iron ore in India. A flotation process has been developed to treat one such ore, namely banded hematite quartzite (BHQ) containing 41.8wt% Fe and 41.5wt% SiO2, by using oleic acid, methyl isobutyl carbinol (MIBC), and sodium silicate as the collector, frother, and dispersant, respectively. The relative effects of these variables have been evaluated in half-normal plots and Pareto charts using central composite rotatable design. A quadratic response model has been developed for both Fe grade and recovery and optimized within the experimental range. The optimum reagent dosages are found to be as follows: collector concentration of 243.58 g/t, dispersant concentration of 195.67 g/t, pH 8.69, and conditioning time of 4.8 min to achieve the maximum Fe grade of 64.25% with 67.33% recovery. The predictions of the model with regard to iron grade and recovery are in good agreement with the experimental results.

Characterization and Processing of Iron Ore Slimes for Recovery of Iron Values

Intensive characterization studies of iron ore slime carried out by X-ray diffraction spectroscope (XRD), scanning electron microscope (SEM-EDS), field emission scanning electron microscope (FESEM), and quantitative mineralogical evaluation by scanning electron microscope (QEMSCAN) are discussed. In slimes, mineral phases like hematite, goethite, gibbsite, kaolinite, and quartz are present in a complex and intricate way. SEM-EDS and QEMSCAN studies indicate that significant amounts of aluminum are associated with both ochreous and vitreous goethite. Hematite and goethite phases are contaminated with some amount of alumina and silica. The liberation of hematite in the coarser fraction (+500 µm) is only 20.6% compared to 40% in the finer fraction (−500 µm) size. A flow sheet, comprising of hydrocyclone and magnetic separation techniques, has been developed to produce an iron concentrate containing ∼63% Fe with 70.7% weight recovery from a feed sample containing 56.8% Fe, 5.1% SiO2, and 6.4% Al2O3.

Optimal Recovery of Iron Values from a Low Grade Iron Ore using Reduction Roasting and Magnetic Separation

A low grade iron ore containing 51.6% Fe, 17.6% SiO2, 4.3% Al2O3, and 3.8% LOI was subjected to reduction roasting followed by low intensity magnetic separation studies. The phase transformation of hematite into magnetite and fayalite due to reduction roasting was investigated using reflected microscope and X-ray diffraction (XRD) techniques. The effects of reduction variables such as reduction time (40−175 min), temperature (750−1000°C), and reductant dosage (3−11%) using activated charcoal were studied. The process was optimized by using central composite rotatable design (CCRD) and response surface methodology. Iron grade from 59−66% with recovery of 9.5−87% was achieved using CCRD experiments. Model equations were developed both for Fe grade and recovery and then optimized within the bounds of experimental conditions. The program predicted 63.3% Fe with 79% recovery with the following optimum conditions: temperature: 950°C, time: 53.04 min, and reductant: 3%.

Characterization and beneficiation studies for the removal of iron from a china clay from India

Abstract A china clay sample from Jharkhand State, India, containing 65.0 wt.% SiO2, 22.7% Al2O3, 1.77% Fe2O3 and 9.10% LOI was subjected to physical beneficiation and acid leaching studies to improve its quality. The clay was characterized by optical microscopy, XRD, and wet chemical analysis methods. Quartz and goethite are the two major impurities. High intensity magnetic separation removed only 10% of the total iron. Experiments with oxalic acid were carried out to establish the leaching kinetics of iron and the effects of acid concentration, time and temperature on iron leaching were also examined. The study demonstrated that ~90% of total iron could be removed using 5% oxalic acid. The dissolution of iron from clay is best described by diffusion of ions through the product layer of constant size spherical particles. The activation energy of the leaching process over the temperature range was calculated to be 51.14 kJ/mol.