Experimental study on preparation of ultralow-ash coal using oil agglomeration method

Experimental study is conducted on preparation of ultralow-ash coal with Nalinhe bituminous coal with a low degree of metamorphism as material by varying the coal particle size, agitating speed, agitating energy, selection and dosages of neutral oil, alcohol and dispersant. Through a series of tests on deashing of Nalinhe with oil agglomeration method, the ash of the coal can be reduced down to 2.51% with a ash removal rate up to 81.02%. It is observed through preliminary study that: alcohol and dispersant can exert an important effect on oil agglomeration; and the reaction between coal and alcohol can lead to change of coal wettability, thus increasing the coal-water contact angle and the hydrophobicity of coal. A study is also made of the principal deashing mechanisms of oil agglomeration method through comparing the variation of infrared spectra following the alcohol-dispersant-coal reaction with the raw coal infrared spectrum, as well as an analysis of the effect produced by surface functional group.