Kinetics Research On Desulfurization From Coal By Grinding And Chemical Method

Taking the high sulfur coal as a research object, the sulfur and ash of the grinded coal had been removed by nitric acid. The activated carbon from the coal had been prepared. The effects of the coal particle size, the concentration of Cd(Ⅱ), the amount of activated carbon and time on adsorption of activated carbon from wastewater containing Cd(Ⅱ) were studied. The pore structure characteristics of coal had been studied by Nitrogen adsorption method (BET). Effects of grinding and pre-treating with nitric acid on inorganic sulfur content of coal had been investigated. The results showed that the specific surface area and pore volume both increased with the decrease of particle size. The microspore surface of coal had the fractal characteristics, and the fractal dimension was 2.48. The sulfur content decreased with the decrease of particle size by grinding. Having pretreated with nitric acid, DFR (desulfurization ratio) of inorganic sulfur could be above 95%, and DFR of total sulfur could be above 70%. And the process had the fractal characteristics, and the fractal dimension was 2.94. The optimized adsorption conditions were following as, 0.054mm of particle size, 35mg/l of Cd(Ⅱ)concentratio, 0.2g of activated carbon and 1h of time.The effects of coal particle size, the concentration of coal slurry, the extraction time and temperature, the ratio of 1,2-propanediol to potassium hydroxide on the removing ratio of organic sulphur for nitric acid pretreatment coal had been studied. Fractal kinetic properties of the inorganic sulfur desulfurization procedures were investigated by using fractal geometric theory. The optimized desulfurization conditions were following, 0.05g/ml of coal water slurry concentration, 90min of reaction time, 0.054mm of granule size and 1:1 volume ratio of 1,2-propanediol to potassium hydroxide at 180℃. Under the condition, the organic sulfur had come down from 0.72% to 0.35%, and the coal defulfurization efficiency can come up to 51.4%. The organic sulfur desulfurization procedure by PG-KOH was also tallied with the fractal kinetic property, and the fractal reactive dimension was 2.57. Fractal dimensions of coal desulfurization reaction (2.57-2.94) were larger than that of surface fractal dimension. It indicated that the desulfurization reaction selectively happened in micropores. This process was conformed to Arrhenius equation. Reaction rate constant, pre-exponential factor and the activation energy increased with the decrease of particle size. The organic sulphur in the coal was chiefly eliminated by the physical extraction.