Nitrogen oxide (NO) gas is one of the major environmental pollutants being generated from the steel industry. Since there are no techniques that can predict how much of NO will be formed from coal, it is extremely required to derive some indices based on the understanding of how coal properties are related with the formation of NO. The current research investigated how coal properties such as nitrogen content, fixed carbon (FC), volatile matter (VM) and functional forms of nitrogen could affect the conversion of nitrogen to NO (X_NO) for anthracite, semi-anthracite and bituminous coals. It was expected that coals containing high nitrogen would provide the highest values of X_NO. However, there was no correlation between nitrogen content and X_NO. A variable that related coal properties and defined the quality of coal was proposed by C_r (FC/VM). For all grades of coals, X_NO tended to decrease as C_r increased. The relationship between nitrogen functional forms and X_NO was highly dependent on coal grade. X_NO value increased when pyridinic-N increased and pyrrolic-N decreased in anthracite and bituminous coals before combustion, and pyrrolic-N increased and pyridinic-N decreased in semi-anthracite coals before combustion. This suggests that pyridinic-N might be considered to be the major functional form that affects the conversion of nitrogen to NO for all the coals measured. NO index for each coal grade was derived by using the previously-mentioned variables affecting X_NO. The linear coefficients of the relations between NO index and X_NO was found to be 0.98, 0.62 and 0.64 for anthracite, semi-anthracite and bituminous coals, respectively. More coals should be measured to validate the proposed NO indices with increased accuracy.

一氧化氮 (NO) 气体是钢铁行业产生的主要环境污染物之一。由于没有技术可以预测煤会生成多少 NO，因此非常需要在了解煤性质与 NO 生成的关系的基础上推导出一些指标。目前的研究调查了煤的氮含量、固定碳 (FC)、挥发性物质 (VM) 和氮的功能形式等煤特性如何影响无烟煤、半无烟煤和烟煤中氮向 NO ( X _NO )的转化。预计含高氮的煤将提供最高值的X _NO。然而，氮含量与X之间没有相关性。_否。C _r (FC/VM)提出了一个与煤炭性质相关并定义煤炭质量的变量。对于所有等级的煤，随着C _{r 的}增加，X _NO趋于减少。氮功能形式与X _NO之间的关系高度依赖于煤品位。X _NO燃烧前无烟煤和烟煤中吡啶-N增加而吡咯-N减少时，其值增加，而半无烟煤燃烧前吡咯-N增加而吡啶-N减少。这表明吡啶-N 可能被认为是影响所有测量煤中氮向 NO 转化的主要功能形式。通过使用前面提到的影响X _{NO 的}变量，推导出每个煤级的 NO 指数。对于无烟煤、半无烟煤和烟煤，发现NO 指数与X _NO之间关系的线性系数分别为0.98、0.62 和 0.64。应该测量更多的煤，以提高准确度来验证所提出的 NO 指数。