Abstract: Both coal gasification slag and iron tailings contain unreacted residual carbon and rich oxide components of silicon,aluminum,iron,and calcium,which can be used as secondary resources to prepare SiAlON ceramics,realizing high-value-added utilization of coal gasification slag.In this work,the carbothermal reduction and nitridation technology was adopted to synthesize SiAlON composite powders,with coal gasification slag as the raw material,iron tailings as the catalyst and carbon black as the reducing agent.The effects of the nitridation temperature (1 425,1 450,and 1 475 ℃),holding time (3,6 and 9 h) and iron tailings addition (10%,20%,30%,40%,50% and 60%,by mass) on the phase composition and microstructure of the nitridation products were studied.The results show that increasing the nitridation temperature or extending the holding time is conducive to the transformation from O’-SiAlON to β-SiAlON.When the nitridation temperature is 1 450 ℃ and the holding time is 6 h,with the increase of the iron tailings addition,β-SiAlON gradually develops from short rods to complete long columns.When the iron tailings addition exceeds 50%,flaky O’-SiAlON is obtained.The iron component forms a large amount of liquid phases at high temperatures and exerts a certain catalytic effect in the carbothermal reduction nitridation,which affects the phase composition and microstructure of SiAlON.

Key words: coal gasification slag, iron tailings, carbothermal reduction nitridation, phase composition

摘要： 煤气化炉渣与铁尾矿中均含有未完全反应的残碳以及丰富的硅、铝、铁、钙氧化物组分,可作为二次资源制备SiAlON陶瓷,实现煤气化炉渣的高附加值利用。采用碳热还原氮化技术,以煤气化炉渣为原料,以铁尾矿为催化剂,炭黑为还原剂,合成SiAlON复合粉体。研究了氮化温度(1 425、1 450和1 475 ℃)、保温时间(3、6、9 h)及铁尾矿加入量(加入质量分数分别为10%、20%、30%、40%、50%和60%)对氮化产物物相组成及显微结构的影响。结果表明:提高氮化温度或延长保温时间均有助于O′-SiAlON向β-SiAlON的转化;当氮化温度为1 450 ℃保温6 h时,随着铁尾矿加入量的增加,β-SiAlON 由短棒状逐渐发育成完整长柱状;当铁尾矿加入量超过50%(w)时,得到片状的O′-SiAlON相;铁组分在高温形成大量液相,在碳热还原氮化中具有一定的催化作用,影响了SiAlON相组成及显微结构。

关键词: 煤气化炉渣, 铁尾矿, 碳热还原氮化, 物相组成