Process and property optimization of ceramsite preparation by Bayan Obo tailings and blast furnace slag

The ceramsite was prepared by using Bayan Obo tailings and blast furnace slag of Baotou Steel as the main raw materials and coal gangue as pore-forming agent, and the process system and the performance of ceramsite were optimized. The phase transformation rules of the ceramsite prepared by multi-source solid waste in sintering method were clarified. The influence of sintering process parameters on ceramsite performance and the purification effect of ceramsite on ammonia nitrogen wastewater were revealed. The results show that the reasonable proportion of raw materials for preparing ceramsite is 60% tailings, 35% blast furnace slag and 5% coal gangue. The reasonable preparation process of ceramsite is preheating at 350 °C for 12 min, increasing the temperature to 750 °C and holding for 60 min, then increasing the temperature to 1130 °C and roasting for 20 min. The cooling method is to cool down with the furnace. The prepared ceramsite has compressive strength of 1.89 MPa, porosity of 51.31%, water absorption of 31.42%, and bulk density of 1.94 g/cm 3 . When the ceramsite is used to treat ammonia nitrogen wastewater, the removal rate of ammonia nitrogen is 47.33%.