This paper provides an overview on the current status of power generation in China using coal gangue. The government regulation towards the use of coal gangue for power generation is introduced. Emission of pollutants and low thermal power plant efficiency are the two major problems for the power industry firing coal gangue. Particulate matter emission control is a problem due to the high ash content. Sulfur emissions from these units are easily controlled mostly through lime/limestone injection and in-situ capture. Overall, efficient power generation using coal gangue is a promising approach to reduce the use of coal resources and reduce the environmental impacts.
Mullite with puncheon-like grains was synthesized by sintering the mixtures of coal gangue and γ-Al2O3 at 1400 °C~1550 °C for 4 h. The phase and microstructure evolution of the mullitization behavior were investigated by XRD, SEM and EDS. Phases of the sintered specimens were mullite, corundum and cristobalite at 1400 °C to 1450 °C. Arise of temperature would enhance mullitization, and total consumption of cristobalite occurred from 1500 °C upward. The in-situ produced primary mullite from gangue upon heating may be seeds for the growth of enenly dispersed mullite puncheons. Specimen sintered at 1550 °C consists of puncheons with an aspect ratio of 2~4, regionally forming an interlocking structure.