Research On Dielectric Properties And Microwave Desulfurization Of Coking Coal

It’s necessary to find an effective method to remove sulfur from coal concerning that the high sulfur content of coking coal can’t be rational utilization. At present, microwave desulfurization is a kind of effective method.In the paper, coking coal was choosed as the object to study the dielectric properties and solutions to remove sulfur from coking coal with microwaves. The vector network was used to test and analysis dielectric properties of model sulfur compounds and coking coal in order to find the factor on them. The orthogonal experiments on desulfurization efficiency were done to study the change rules with different microwave powers, irradiation time, leaching agent concentration(concentration of methanol, KOH, glacial acetic acid-hydrogen peroxide). And on this condition, the changes were analysed on the organic sulfur with XPS and the structure with infrared spectrum in coal. Finally the follow conclusions were reached.1. With the frequency 0.1~6.5GHz, the relative dielectric constant of Xinyu coking coal mixing 1% to 5% sulfur / pyrite / dibenzothiophene have the trend that climbing up and then declining with the frequency increasing. The relative dielectric loss factor and dielectric loss tangent keep the similar trend with mixed amount increasing. And relative dielectric loss at 2450 MHz is greater than the value at 915 MHz. Mixing 0 to 50% calcite / kaolinite / quartz, Xinyu coking coal the relative dielectric constant variation basically the same. Relative dielectric loss at 915 MHz is greater than the value at 2450 MHz. At 2450 MHz, when methanol concentration was 2% or KOH solution concentration is 0.05mol/L or glacial acetic acid-hydrogen peroxide solution ratio of 1:2, the relative dielectric loss of Xinyu coking coal is the largest.2. The best removing sulfur conditions from Xinyu coking and these which were soaked by every extraction agent are lasting 8 minutes’ irradiation, at 720 W of microwave power, and with the increase of microwave power and irradiation time changes in total sulfur removal rate was 7.84% ~ 7.84%. Under the best of microwave irradiation conditions, when no extraction agent, thiophene sulfur removal of Xinyu coking coal is not essential; mptimum volume concentration of 2% of methanol extracting coal, showed that sulfone sulfur was completely off; optimal volume concentration of 0.05 mol/L of KOH extracting ones, showed that thiophene sulfur was removed partly, sulfone sulfur has been completely removed; when optimum extraction of coal samples ratio of 1:2 of acetic acid-hydrogen peroxide extracting ones, XPS spectra showed thiophene sulfur and sulfoxide sulfur were removed easier, but the content of sulfone sulfur increased.