Ratnakar Singh

Development of a Generalized Strategy for Dry Beneficiation of Fine Coal over a Vibrating Inclined Deck

Beneficiation of coal fines of size −1.0 + 0.1 mm using an air table under controlled fluidization was investigated. Widely different feed coals with ash values ranging from 30–50% were shown to respond well to the process. Interactions among process variables towards influencing the separation performance were studied carefully to have a firm control over the process. Detailed statistical analysis of the experimental data was carried out and in-depth understanding of the process was accomplished through various statistical plots. The preferred operating regimes were identified for three different coals to achieve maximum mass yield for targeted product qualities. Flow sheets were developed for all the three coals investigated in order to obtain multiple usable products using a maximum of four stages of operation of the air table. A generalized strategy for dry cleaning of any coal with given characteristics was developed such that application potential of the air table can be enhanced.

Investigation on the Effect of Ultrasonic Pretreatment on Selective Separation of Iron Values from Iron Ore Tailings by Flocculation

Abstract Selective flocculation studies were carried out on Barsuan iron ore tailings having 50.5% iron, 7.2% alumina, and 7.8% silica in the absence and presence of ultrasonication at different experimental conditions using sodium hexametaphosphate as a dispersant and starch as a flocculant. The imposition of ultrasonication resulted in a marked improvement in grade as well as recovery. The results indicate that ultrasonication is able to mitigate the adverse effects of gangue materials. A concentrate assaying 59% iron with 75% recovery could be obtained without ultrasonication, while the application of ultrasonication led to an improvement in concentrate grade to 65% with a corresponding increase in recovery to 91%. The improvement is attributed to the disruption caused at a solid/liquid interface which results in favorable modification of the mineral surface, facilitating selective adsorption of flocculant on the iron ore fines. This, in turn, leads to enhancement in selectivity and recovery. In additi...

Utilization of Iron Ore Slimes: A Future Prospective

In India, iron ores processing industries play a vital role in the Indian economy. During the washing and processing of iron ores, slimes less than 0.15 mm are generated and discarded into the tailing pond. These slimes need processing as they cannot be used directly in blast furnaces. In the present investigation, a typical iron ore slime sample containing 59.22% Fe, 4.76% SiO2, and 4.57% Al2O3 was taken. The desliming operation was carried out by using 2” Mozley hydrocyclone. The process variables used to attain the optimum condition of desliming include the spigot opening, the feed pressure, and the diameter of the vortex finder maintaining the pulp density at 10% solid. The deslimed sample was treated by different techniques including an enhanced gravity separator to achieve iron concentrate with 65% Fe so that it can be used for steel making through pelletization. The yield of the magnetic concentrate is about 46.8% with 65% Fe. To improve the yield, the overflow from 2” hydrocyclone and the rejects from magnetic separation were deslimed and processed to recover the iron values. The final concentrate is 74% yield with 64.8% Fe, 1.76% SiO2, and 1.8% Al2O3.

Split Processing of High Ash Indian Coking Coal Fines Using Jameson Flotation Cell

The processing of two samples of high ash Indian coking coal fines (−500 μm) has been studied. Mechanical cell flotation of two coal samples resulted in poor recovery of combustibles at a specified ash content of 17%. The use of Jameson Cell for flotation was also found helpless in improving the performance. The poor recovery of combustibles was attributed to low recovery of coarse particles (>300 μm). Split processing involving spiral concentration of the coarser fraction (−500 + 100 μm) and Jameson Cell flotation of the −100-μm fraction resulted in an improved overall performance. Substantial improvement in the yield of clean coal at the same target ash (17%) could be achieved in split processing.

Efficiency Study of a Water-Only Cyclone by Experimental and Data Modeling Techniques when Cleaning Indian Coal Fines

Experiments have been conducted on a water-only cyclone in conjunction with washability studies for Patherdih and Munidih coal samples of Eastern India to characterize the cyclone efficiency. Data driven semi-empirical performance models have been developed using in-house experimental data. Washability studies on the Patherdih sample have been undertaken to determine the specific gravity of separation for a targeted coal quality. Size classification analysis has been conducted for the Munidih sample to estimate the cut-size. The Mayer and partition curves have been generated from float-and-sink analysis. Subsequently, reduced efficiency curves have been constructed using specific gravity as well as size classification data. The Rosin-Rammler and logistic distribution functions have been employed to model the data to generate the reduced efficiency curve, which characterizes the classification efficiency. Model parameters have been estimated for these distribution functions. Parametric sensitivity analysis was carried out by changing the operating parameters, namely, apex diameter, and feed inlet pressure and percentage solids in the feed to study the classification behavior. Model predictions were found to be in good agreement with the published literature. Efficiency mapping by the Rosin-Rammler distribution was found to be well suited for the Patherdih coal and both the Rosin-Rammler and logistic distributions are equally appropriate for Munidih coal.