TG-FTIR在煤灰研究中的应用——真实煤灰和模拟灰受热气体释放规律比较

Application of TG-FTIR in coal ash——Comparison of gas release from real and factitious ash during heating process

我国的煤炭种类多,煤灰组成千变万化,从中找到明确的矿物转变规律并非易事。为探索用模拟灰替代真实煤灰开展高温转变规律研究的可行性,依据镇雄煤(ZX)煤灰化学成分,利用Fe S2矿物和Fe2O3、Si O2、Al2O3等分析纯化学试剂配制模拟灰,测试灰熔融温度,并借助热重红外联用(TG-FTIR)技术比较ZX真实煤灰和模拟灰在氮气气氛下升温过程中的质量变化及气态产物组成。结果表明,模拟灰的流动温度接近ZX煤灰的流动温度,最大相差49℃。当温度大于770℃时,含有Fe S2的模拟灰与真实煤灰的TG-DTG曲线变化趋势一致。FTIR谱图显示两者释放的气体种类相同,1080℃左右都产生SO2气体,此时的硫来源于黄铁矿的部分氧化产物Fe Sx。含有Fe S2的模拟灰在高温下的变化更接近真实煤灰。

There is a great variety of coal whose ash composition is greatly different in China. The behavior of coal ash at high temperature is so complicated that it is difficult to understand definitely minerals transformation. In order to explore the feasibility of the factitious ash instead of coal ash for studying transformation mechanism, the factitious ash was prepared from FeS2 mineral and analytically pure reagents such as Fe2O3, SiO2, and Al2O3 based on the composition of ZX coal ash. The ash fusion temperatures of samples were tested. Mass change and gaseous product compositions of the factitious ash were analyzed by thermogravimetry combining with Fourier-transform infrared spectroscopy （TG-FTIR） in the nitrogen atmosphere during temperature increase, in order to compare with ZX coal ash. The flow temperature （FT） of the factitious ash was approximate to that of ZX coal ash, and the maximum difference was 49℃. The TG results showed that the mass loss tendency of both the factitious ash containing FeS2 and ZX coal ash was similar at the temperature above 770℃. It was observed that the gaseous products of the two ash samples were the same in species from the FTIR spectra. SO2 was released at the temperature of 1080℃, which might be derived from FeSx, partial oxidation of pyrite. The variation of the factitious ash containing FeS2 at high temperature was more similar to that of ZX coal ash.