Beneficiation of Ovbiomu Low Grade Coal Using Froth Flotation for Industrial Applications

Abstract

Coal flotation is a highly effective separation method utilizing the differences in surface properties of coal and gangue minerals. This research entailed the beneficiation by froth flotation of low-grade coal from Obviomu Coal Mines, Edo State, Nigeria for improvement of the fixed carbon content and calorific value for industrial application. 50 kg of coal samples were collected from five different pits and were reduced using a jaw crusher to a size of 1400 μm, pulverized to a size of 1100μm. A 500-gram sample of coal was weighed and ground in a ball mill until 100% of it passed through a 250-micrometer sieve; these steps were then repeated for sieve sizes of 180, 125, 90, and 63 micrometers, respectively. A DENVER flotation cell was charged with 500 grams of well-ground coal sample of 250 µm sieve size. The process was then repeated with sieve sizes of 180 μm, 125 μm, 90 μm, and 63 μm, in that order, the results of the froth flotation beneficiation method revealed that, the weight in mass of the concentrate at sieve sizes of 250 μm, 180 μm, 125 μm, 90 μm, and 63 μm was found to be 319.209 grams, 119.227 grams, 113.028 grams, 237.657 grams, and 141.343 grams, respectively, while the weight in mass of the tailings was found to be 180.791 grams, 380.773 grams, 386.972 grams, 262.343 grams, and 358.657 grams, respectively. The calorific values of the concentrate and tailings were measured using a CalK2 bomb calorimeter. At sieve sizes of 250 μm, 180 μm, 125 μm, 90 μm, and 63 μm, the concentrate's values were found to be 44.45 MJ/Kg, 43.84 MJ/Kg, 43.66 MJ/Kg, 46.02 MJ/Kg, and 43.48 MJ/Kg, respectively, while the calorific values of the tailings were found to be 3.13 MJ/Kg, 3.31 MJ/Kg, 0.79 MJ/Kg, 3.25 MJ/Kg, and 0.18 MJ/Kg respectively. The fixed carbon content at sieve sizes of 250 μm, 180 μm, 125 μm, 90 μm, and 63 μm was found to be 74.00%, 73.000%, 72.70%, 76.60%, and 72.40%, respectively, in the concentrate, while 5.20%, 5.50 %, 1.30%, 5.40%, and 0.30 % were found in the tailings. This information was obtained through proximate analysis of the concentrate and tailings at different sieve sizes. At 90 μm, the optimum sieve size, a rise in the fixed carbon content of the coal samples was recorded, accounting for 88.53% increase of the calorific value. The study concludes that direct froth flotation is a viable and efficient method for improving the quality of low-grade coal for industrial use.