Abstract: SCR and SNCR technology are commonly used to reduce NO_x emission of aluminum hydroxide gaseous suspension calciners(GSC). However,due to the problems of contamination on catalyst and ammonia slip,it is urgent to develop a new scheme to reduce NO_x emission. Fuel gas recirculation and air staged combustion are potential approaches to reduce NO_x emissions of aluminum hydroxide GSC.However,the effects of fuel gas recirculation and air staging on operating parameters of GSC are still unclear. In the present study,taking a 3 000 t/d aluminum hydroxide GSC as the research object,the effects of the flue gas recirculation and air staging on the GSC operating parameters were investigated. It is found that when the flue gas recirculation rate is 20%,the total excess air ratio of the system is reduced to about 1.1,which can maintain a large primary air volume,ensure the suspension roasting state,and make the lower part of the main roasting furnace( P04) achieve a reductive atmosphere,thus inhibiting the formation of NO_x. The changes in the separation efficiency of each cyclone in GSC caused by the flue gas recirculation and air staging ware negligible when the flue gas recirculation ratio are below 20% and the over fire air ratio of the air staged combustion are below 25%. The flue gas recirculation and air staged combustion result in a decrease of the calcination temperature if the fuel distribution is not well adjusted,which may have adverse effects on the quality of alumina products. However,by optimizing fuel distribution of the GSC calciner,the influence of flue gas recirculation and air staging on operating parameters can be largely reduced. When the flue gas recirculation ratio reaches 20% and the over fire air ratio reaches 25%,the lower part of the main furnace of the GSC calciner can achieve a reductive atmosphere while the aluminum hydroxide calcination temperature and overall thermal efficiency are still ensured,which provides the necessary condition for the low-NO_xcombustion design of the GSC process.