The greater demand for high-quality iron ores has forced the iron and steel industries to utilize low-grade iron ores, such as banded hematite quartzite (BHQ). In the present work, a striped hematite quartzite sample from the Haraginadoni area, in the Sandur schist belt, Ballari District, Karnataka, India, was subjected to characterization studies and conventional mineral processing methods to produce pellet-grade concentrate, assayed as Fe > 63.0%, SiO2 + Al2O3 < 7%, (Al2O3/SiO2 < 0.5). The sample was analyzed as 35.70% Fe, 47.44% SiO2, 0.75% Al2O3, 0.06% Mn, 0.07% TiO2, 0.03% P, 0.02% S, and 0.83% LOI. We focused on two routes of beneficiating BHQ samples: (1) conventional gravity followed by reverse floatation and (2) magnetic separation followed by cleaning of magnetic concentrate by reverse floatation. Route 1, achieved pellet-grade concentrate through assaying, and was 63.73% Fe, 6.20% SiO2, 0.19% Al2O3, 0.03% Al2O3/SiO2, and 0.23% LOI, D80 45 µm, with 70.1% Fe recovery and 62.8% concentration efficiency at 39.6 wt% yield. Using Route 2, the process consisted of WHIMS at −74 µm, D80 54 µm, 10,000 Gauss, and with a 3 mm ball matrix, followed by flotation of the WHIMS concentrate, which produced a concentrate through assaying and was 63.34% Fe, 6.30% SiO2, 0.20% Al2O3 (0.03 Al2O3/SiO2), and 0.20% LOI with 77.4% Fe recovery, achieving a 68.8% concentration efficiency at 44.0 wt% yield, meeting pellet-grade specifications. Comparing and analyzing both routes for the concentration methods, Route 2, i.e., WHIMS and the reverse flotation of WHIMS concentrate, was amenable compared to Route 1.

Recovery and grade are the two crucial performance parameters commonly used in mineral processing plant operations. These two parameters are interdependent. An increase in recovery would result in a decreased product grade and vice versa. The present study enumerates concentration efficiency (CE),which can be adopted exclusively for processing low-grade hematite ore by WHIMS—the reverse flotation route to produce a pellet grade concentrate. In this study, the ore’s amenability by wet high-intensity magnetic separation followed by the reverse flotation of a magnetic concentrate route is investigated on BHQ samples of the Sandur schist belt (Kumaraswamy hills), India, after its characterization by microscopic and XRD studies. Dodecyl amine acetate was used as a collector to float siliceous gangue while depressing hematite using the freshly synthesized caustic starch as a depressant. The separation efficiency of the flotation was evaluated by estimating the grade, recovery, and concentration efficiency. The WHIMS conducted using the feed with the particle size minus 106 µm (d80 = 82 µm) followed by reverse flotation produced a pellet grade concentrate assaying 64.60% Fe, a 0.32 alumina-to-silica ratio with 60.4% Fe recovery, and a yield of 37.4% with 79.0% concentration separation efficiency.

Settling tests were conducted on the washery effluent using three types of flocculants namely cationic (Telfloc-3674F), anionic (Magna-1011) and non-ionic (Nalco-83370 + ). For the study purpose coal washery effluent (having pH of 8.72) was collected from a newly commissioned plant-thickener. Tests were conducted by varying the pH of the pulp at three levels of acidic (4.0), alkaline (11.0) and the natural pH (8.72) of the as collected effluent, besides the flocculent dosages varied at four levels (2, 4, 6 and 8gpt) for each of the flocculants stated. The results of these tests, estimated in terms of initial settling rate and turbidity indicated that; among the three flocculants tested Telfloc-3674F and Magna-1011 gave best results as compared to Nalco-83370 + flocculent at a washery water pH 8.72. The effect of molecular weight of the flocculants on settling of solids in effluent has been established in terms of the kinetics with a characteristic number for each of the type of flocculants used.