Effect of some operational parameters on desulphurization of high sulphur Indian coal by KOH leaching

Abstract

This paper presents an experimental study on the effect of potassium hydroxide concentration and reaction time on coal properties during desulphurization of high sulphur Indian coal. Experimental results showed that maximum of 36.79% of total sulphur can be removed from coal by potassium hydroxide leaching with 20% potassium hydroxide concentration and 24 h contact time at atmospheric condition. Total sulphur reduction was contributed by 45.03-49.01% pyritic sulphur, 24.10-33.73% sulphate sulphur and 20.93-30.62% organic sulphur depending on potassium hydroxide concentration of 5-20% and reaction time of 6-24 h. Experimental result shows that ash% of coal increased from 8.33 to 14.09% due to accumulation of insoluble potassium aluminosilicate in the coal. Gross calorific value of coal decreased from 6854 to 6084 kcal/kg due to increase of ash content of coal and loss of some combustible matter in leaching process. Physico-chemical characterizations of raw and treated coal samples were carried out by using field emission scanning electron microscope, Fourier transform infrared, petrographic analysis, thermogravimetric analysis and differential thermogravimetry to appraise the product quality. Field emission scanning electron microscope and coal petrographic image infer the occurrence of pitting and cavitation in the coal structure due to removal of pyrite sulphur (1.51-1.21%) from coal which causes escalation of vitrinite (67.65-70.43%) and few amounts of inertinite (18.03-18.86%) and liptinite (1.24-1.27%) as macerals. Thermogravimetric analysis-differential thermogravimetry analysis infers the improvement in combustion characteristics of treated coal by reduction in peak combustion temperature.

The evolution characteristics of organic sulfur structure in various Chinese high organic sulfur coals

“…The FTIR spectrum of the organic sulfur structure in coal was analyzed by peak fitting. According to previous studies (Colthup et al., 1990; Kofranek et al., 1992; Li and Li, 1991; Nunziante et al., 1999; Quigley, 1996), the assignment of organic sulfur compound absorption peaks is listed in Table 5 and the absorption areas of curve-fitting FTIR spectrum of all samples are listed in Table 6. According to the results of previous studies (Guo et al., 1996; Mastalerz and Bustin, 1993), the ratios of the relative abundance of aromatic to aliphatic functional groups, I 1 =areas of (3000–3100)/areas of (2800–3000) and I 2 =areas of (700–900)/areas of (2800–3000), are used to indicate the aromaticity of coal.…”

Pozyskiwanie węgla kamiennego z uwzględnieniem wybranych regulacji środowiskowych – studium przypadku polskiego sektora energetycznego

“…The emission factors of SO 2 were determined according to the formula (GDEP 2007;Frigge et al 2017;Ken and Nandi 2018). The emission factor SO 2 EmFactorSO2 pp,y is calculated based on the sulfur content of the coal delivered to power plants pp in year y (Equation 1).…”

Efficient Demineralization and Desulfurization of Lignite Coal using Alkali and Alkali-Acid Follow up Treatments for Reduced Flue Gas Emissions and Enhanced Calorific Value: A Comparative Study

“…The mineral matter in coal can include inorganic compounds such as sulfur, nitrogen, ash, and trace elements like mercury, arsenic, and lead. Demineralization techniques are often employed to enhance the quality of coal and reduce its environmental impact when used as a fuel [2,3]. The presence of minerals in coal can lead to several issues during combustion, such as increased emissions of pollutants like sulfur dioxide and nitrogen oxides.…”