Formation of Carbon Nanostructures During Chemical Demineralization of Indian Coals

Dash, Pratik Swarup; Sriramoju, Santosh Kumar; Prasad, D. H. L.; Banerjee, P. K.; Ganguly, Sayan; Kargupta, Kajari

doi:10.1080/19392699.2014.891584

Cited by 11 publications

(1 citation statement)

References 12 publications

(14 reference statements)

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“…Chemical beneficiation requires fine coal (less than 500 micron), so that the active surface for reagent to react will be more, but handling of fine coal requires more water/aqueous reagents to avoid frequent choking in the pipelines. Leaching process demonstrated till pilot scale (Dash et al, 2013(Dash et al, , 2014(Dash et al, , 2015a(Dash et al, , 2015bSuresh et al, 2015, Lingam et al, 2016Sriramoju et al, 2016aSriramoju et al, , 2016b, but the economics of the process purely depends on maximum recovery of reagents (alkali and acid) and regeneration of used chemicals. Steel and Patrick (2004) studied the leaching kinetics with hydrofluoric acid and the regeneration of the spent acid is carried out by distillation in nitric acid stream followed by the pyrohydrolysis of solids above 500°C temperature.…”

Section: Introductionmentioning

confidence: 99%

Study on regeneration of spent hydrochloric acid in chemical coal leaching process

Sriramoju

Dash

2019

IJEWM

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For Indian coals, chemical leaching process has better advantage over the conventional physical cleaning techniques due to its drift origin. Coal leaching is a two-stage process where alkali and acid leaching cycles are used, where most of the ash constituents are accumulated in the spent acid and hence purification of spent acid containing silica, alumina, iron, calcium and magnesium is of great importance. Four different methods namely adsorption using activated carbon, ion exchange with anion exchange resin, pyrohydrolysis and stage-wise neutralisation are studied. Results with adsorption and ion exchange techniques are poor and a maximum of 50% removal is observed. Results indicate that, pyrohydrolysis shows better performance with > 99% pure hydrochloric acid as product but it is energy intensive. Stage-wise neutralisation technique is promising for dilute acid, where silica is precipitated by digestion and it produces magnesium oxide and calcium salt with 86.7% and 93.86% purity respectively.

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