准东煤在燃烧过程中的矿物演变过程及Na、Ca释放规律

Mineral Conversion Regularity and Release Behavior of Na, Ca During Zhundong Coal's Combustion

选取天池能源煤作为研究对象,对比分析高、低温灰样中的物相变化,并通过低温灰热重实验深入了解了燃煤过程中准东煤的矿物演变规律。测定不同热处理温度下所得灰样的Na、Ca含量,得到其释放规律,并用Factsage软件模拟出Na、Ca的析出形式。结果表明,准东煤的原始矿物主要有石膏、方解石、石英、高岭石、黄铁矿等。在燃烧过程中,矿物间发生了复杂的化学反应并最终生成钙铁铝石、斜硅钙石等。实验发现,煤中Na在400~600℃间开始析出,Ca在600℃前部分析出,1 000℃后析出最快。结合Factsage的模拟结果,推测1 000℃前Na的主要析出形式为Na Cl（g）,1 000℃后以NaO H（g）和Na2SO4（g）的形式析出。Ca在1 000℃后与灰中铁、硅等矿物形成低温共熔体,达到熔融状态后析出,含量急剧下降。

Tianchi Energy coal was selected as the research object, and phase changes in high and low temperature ashes were comparatively analyzed. Mineral conversion in heating process was thoroughly and meticulously studied through thermogravimetric experiment of low-temperature ash. Contents of Na and Ca in coal ashes made at different temperatures were measured respectively to observe their release regularities, and precipitating types of Na, Ca were simulated by Factsage. Results show that the original minerals of Zhundong coal mainly include calcium sulfate hydrate, calcite, quartz, kaolinite and pyrite. During the process of combustion, complex chemical reactions occur among these minerals, and they transform to brownmillerite, calcium silicate, et al. Experiment results show that Na in coal begins to precipitate during 400-600 ℃, Ca partially precipitates before 600 ℃ and precipitates fastest after 1 000 ℃.Combining with simulation results, it＇s speculated that Na precipitates in the form of NaCl（g） before 1 000 ℃. After 1 000 ℃,＇Na precipitates in the form of NaOH（g） and Na2SO4（g）. Eutectics are formed when Ca interacts with iron and silicon containing minerals after 1 000 ℃. The eutectics precipitate at molten state, which leads to sharp decrease of Ca.