摘要
富铁煤在我国分布广泛,研究富铁煤在高温高压下的矿物转化特性对于其高效利用十分必要。采用加压固定床反应器,研究了新疆准东富铁低阶煤(ZC)在水蒸气气化过程中的矿物转化特性。利用XRD、SEM-EDS和拉曼光谱等手段对原煤、热解半焦和气化过程的残渣进行了矿物组成、形貌特征和有机碳微观结构分析。研究发现,典型新疆富铁低阶煤中的铁主要以菱铁矿和铁闪锌矿的形式存在。在灰化过程中,500℃温度使原煤中的含铁矿物转化为赤铁矿,标准灰化温度815℃部分形成铁尖晶石和铁橄榄石等含铁的低温共熔玻璃体。在氮气气氛下热解,半焦中铁的存在形式主要是单质铁。典型新疆富铁低阶煤在水蒸气气化过程中,首先在炭基体表面形成含钙、钠的硅铝酸盐低熔点矿物相。随着气化压力的增加,这种低熔点矿物相含量增加,说明压力能够促进含钙、钠低熔点硅铝酸盐的生成。压力升高到3 MPa,钙铁斜长石晶相含量增加,升高的压力能够促进富铁矿物参与到硅铝酸盐玻璃相的形成过程中,这将使灰的熔融温度进一步降低。气化时间对矿物转化的影响较为复杂,随着气化时间的增加,气化残渣中含铁矿物相的种类和含量都有所增加,在气化时间3 h条件下,主要生成含铁的硅铝酸盐低温共熔物和含铁硅酸盐,如钙铁辉石和钙铁榴石,这主要是因为随着气化时间的增加,阻碍灰分颗粒相互接触的炭基体消失,使得矿物相得到充分的接触。未反应的含铁矿物在气化剂的存在下被氧化生成赤铁矿。含铁矿物的存在,同时也促进了低温共熔物在炭基体表面的聚集,在一定程度上抑制了碳结构由有序向无定型的转化。
Iron-rich coal is widely distributed in China,and it is necessary to study the mineral transformation of iron-rich coal under elevated temperature and pressure for expanding its utilization.Using a pressurized fixed bed reactor,the mineral transformation characteristics of the Xinjiang Zhundong iron-rich low-rank coal(ZC)were studied during steam gasification.The mineral composition,morphological characteristics and organic carbon microstructure of the raw coal,pyrolysis semi-coke and gasification residue were analyzed by XRD,SEM-EDS and Raman spectroscopy.The results show that the iron in the ZC coal mainly exists in the form of siderite and sphalerite.In the ashing process,the iron-bearing minerals in raw coal are converted into hematite at 500℃,and the iron-bearing low-temperature eutectic glass bodies such as iron spinel and fayalite are partially formed at 815℃.In the semi-coke obtained by pyrolysis under nitrogen atmosphere,the existence form of iron is mainly elemental iron.In the process of steam gasification of the ZC coal,the calcium and sodium-containing aluminosilicate low-melting mineral phase is first formed on the surface of carbon matrix.With the increase of gasification pressure,the content of low-melting mineral phase increases.It indicates that the pressure can promote the formation of calcium and sodium-containing low-melting aluminosilicates.At 3 MPa,the content of the plagioclase crystal phase increases,and the increased pressure can promote the significant participation of iron-rich minerals in the formation of the aluminosilicate glass phase,which will further reduce the ash melting temperature.The effect of gasification time on mineral transformation is more complex.With the increase of gasification time,the type and content of the iron-bearing mineral phase in the gasification residues increase.Under the gasification time of three hours,the low-temperature eutectic of iron-containing aluminosilicate and iron-containing silicates,such as ferric pyroxene and garnet,are mainly formed,wh
作者
吕俊鑫
王永刚
鲍亚寒
林雄超
许德平
LÜJunxin;WANG Yonggang;BAO Yahan;LIN Xiongchao;XU Deping(School of Chemical and Environmental Engineering,China University of Mining&Technology-Beijing,Beijing 100083,China)
出处
《煤炭学报》
EI
CAS
CSCD
北大核心
2023年第3期1365-1375,共11页
Journal of China Coal Society
基金
国家自然科学基金重点资助项目(42030807)。
关键词
富铁煤
低阶煤
气化
无机矿物
碳结构
iron-rich coal
low-rank coal
gasification
mineral matter
char structure
