Desulfurization of coal by oxidation in alkaline solutions

Chuang, K.C.; Markuszewski, R.; Wheelock, T.D.

doi:10.1016/0378-3820(83)90024-3

Cited by 39 publications

(11 citation statements)

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“…He concluded that rate of reaction was inversely proportional to the coal particle size, he also observed that mass transfer rate was inversely proportional to square root of coal particle size, however an optimum particle size should be decided for desulfurization, because a su cient amount of energy is required for grinding and weighing of coal during size reduction. Chuang (Chuang, Markuszewski, and Wheelock 1983) observed that Time for complete conversion of FeS 2 to hematite depend up on the square root of particle size. Guru (Gürü, Sariöz, and Çakanyildirim 2008) performed the leaching of Turkey coal with H 2 O 2 as oxidative agent, he observed that rate of desulfurization was decreased with increase in particle size, the minimum particle size in his experiment was 0.25mm and larger was 0.45mm and the reaction time was12 hours.…”

Section: Effect Of Particle Sizementioning

confidence: 99%

“…He calculated the activation energy for the reaction to be 6300 calory per mole. K C (Chuang, Markuszewski, and Wheelock 1983) Chuang leached the American coal in oxygen and in air by oxidation in alkaline (NaOH) solution. He observed that rate of reaction (oxidation reaction) was proportional to the oxygen partial pressure, hence he decided that in rst step pyrite reacts with oxygen forms hematite and sulfuric acid and then immediately this acid is to be neutralized with alkali, the reaction was rst order reaction.…”

Section: Introductionmentioning

confidence: 99%

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Desulfurization of thar lignite by oxidative alkali leaching under pressure

Usto

Abbasi

Maitlo

et al. 2021

International Journal of Coal Preparation and Utilization

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Pakistan is the world largest lignite bearing country in the world due to the Thar coal reserves. Sulfur contained in this coal need to be removed prior to combustion. Oxidative alkali leaching in dissolved oxygen technique was used to remove the sulfur from Thar coal. This method removed enough all three types of sulfur; about 90% pyretic sulfur, 78% organic sulfur and 50% sulfate sulfur and more than 82S% of total sulfur removal was achieved. Effect of various reaction parameters were observed, it was investigated that reaction time and partial pressure of oxygen has positive effect on the desulfurization, higher the reaction time and oxygen partial pressure higher the degree of desulfurization, also the desulfurization increased with increase in reaction temperature and alkali concentration till some optimum value and then decreases with further increase in value of temperature and concentration of alkali, although desulfurization was observed maximum with minimum particle size. Coal was also characterized with Thermogravimetric Analysis (TGA) and Testo smoke number to investigate the combustion behavior of processed coal. It was observed that combustion properties of processed coal were improved and black smoke in processed coal was reduced.

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Section: Effect Of Particle Sizementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Desulfurization of thar lignite by oxidative alkali leaching under pressure

Usto

Abbasi

Maitlo

et al. 2021

International Journal of Coal Preparation and Utilization

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“…Various chemical desulphurisation techniques have been applied to coal and among these are the use of bases such as sodium carbonate 4,5 and some organic bases (sodium methoxide, sodium butoxide and sodium benzoxide) 6,7 . Recently, Balaz et al 8 reported the use of simultaneous grinding and alkaline chemical leaching process (GACL) on brown coal and found that more than 41% of total sulphur reduction was achieved.…”

Section: Introductionmentioning

confidence: 99%

Chemical Desulphurisation of Sub-Bituminous High Sulphur Indonesian Coal via Peroxyacetic Acid Treatment

Ishak

Ismail

Nawi

et al. 2017

AJSTD

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The chemical desulphurisation from an Indonesian high sulphur sub-bituminous Banjarmasin Haji Ali-Aliansar coal was investigated using the peroxyacetic acid (PAA), a mild oxidising agent. A mixture of hydrogen peroxide : acetic acid (i.e. 30 : 70 by volume ratio with 6% of hydrogen peroxide concentration) at 50˚C of reaction temperature is capable of reducing the total sulphur content in the coal from 3.46% to 1.29% by weight, corresponding to the removal of up to ca. 72% of the total sulphur; both the inorganic (mainly pyrite) and organic sulphur forms, and approximately 10 to 44% of ashes in the coal. The simultaneous removal of both inorganic and organic sulphur forms was measured with respect to reagent volume mixed ratio, reaction temperature and hydrogen peroxide concentrations. The success of desulphurisation was measured by the reduction of the total sulphur content of the desulphurised product, its S/ C atomic ratios and ash yields of the treated coal. In general, all inorganic and some of the organic sulphur could be removed from the coal using mild conditions without severely affecting the coal microstructure as observed via the Scanning Electron Microscope with Energy Dispersive X-ray (SEM-EDX).

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“…Oxidation of coal has been widely studied in coal molecular structure investigation and to obtain high-value organic chemicals such as low-molecular weight fatty acids and some long-chain aliphatic hydrocarbons [71][72][73]. It has also been reported in other coal related industries, but with less attention, such as coal coking [74], caking [75], desulfurization before utilization in power plants [76,77], coal self-heating and subsequent spontaneous combustion in coal mines and stock piles [78][79][80] and even in terms of the biogenetic methane production [81]. A comprehensive overview of coal oxidation methods under mild conditions has been provided by Yu et al (2014), consisting primarily of hydrogen peroxide (H2O2), sodium hypochlorite (NaClO) and secondarily of potassium permanganate (KMnO4), oxidizing acid, oxygen, and ozone [82].…”

Section: Oxidant Candidates and Their Reaction With Organic Mattersmentioning

confidence: 99%

“…Coal oxidation has been reported widely in the areas such as coal molecular structure investigation and obtaining high-value organic chemicals [71][72][73], coal desulfurization before utilization in power plants [76,77], coal self-heating and subsequent spontaneous combustion in coal mines and stock piles [78][79][80] and even in terms of the biogenetic methane production [81]. In these studies, different oxidants have been used mainly including NaClO, KMnO4 and H2O2.…”

Section: Conclusion Of the Literature Reviewmentioning

confidence: 99%

Oxidant stimulation of coal seams to increase coal seam permeability

Jing¹

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Low permeability renders a significant fraction of coal seam gas (CSG) resources subeconomic. An effective permeability enhancement strategy is thereby crucial in monetising low permeability CSG resources. Though employed in a number of coal basins, conventional low permeability stimulation treatments have not been ubiquitously successful. The natural cleat system of coal is the primary conduit for gas flow and low permeability is in many cases attributed to low cleat porosity and connectivity. Cleat demineralisation by acid has been addressed previously with mixed results. This thesis explores the possibility that coal cleats could be etched and the cleat aperture could be widened by use of oxidants. It could have high potential to increase the cleat porosity and connectivity, thus enhancing the coal permeability in the near well bore region where high permeability is critical. Two coal samples, from the Bowen (coal B) and Surat (coal S) basins in Queensland, Australia were selected. A screening method was designed based on time-lapse photography to assess the extent of coal particle size change immersed in potential oxidants, including sodium hypochlorite (NaClO), potassium permanganate (KMnO4), hydrogen peroxide (H2O2), and potassium persulfate (K2S2O8). Results show coal solubilisation and the propensity to swell in all the oxidants as well as coal breakage in specific oxidants (NaClO and KMnO4). Both coals react vigorously with NaClO and KMnO4, where massive coal solubilisation occurs, but react only slightly with K2S2O8 and H2O2. Given the solid products of the KMnO4 reaction (MnO2), NaClO is selected as the most promising oxidant stimulant. After NaClO treatment, the total accessible pore volume of both coals increases. Pore size distributions indicate that oxidation can enlarge the pores, particularly for coal S, which was confirmed by scanning electron microscopy (SEM). A microfluidic cleat flow cell (CFC) was used to inject NaClO into artificial channels scribed on polished coal samples, and measured an increase in the widths of the channels after NaClO treatment. The channel aperture increase indicates that coal solubilisation/etching is a more dominant mechanism than coal swelling when coal is confined in coal cleats. The channel aperture of coal S increases more than coal B.

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Desulfurization of coal by oxidation in alkaline solutions

Cited by 39 publications

References 1 publication

Desulfurization of thar lignite by oxidative alkali leaching under pressure

Desulfurization of thar lignite by oxidative alkali leaching under pressure

Chemical Desulphurisation of Sub-Bituminous High Sulphur Indonesian Coal via Peroxyacetic Acid Treatment

Oxidant stimulation of coal seams to increase coal seam permeability

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