No abstract

Large amount of industrial wastes are discharged from commercial production every year. 1 Lime mud is a kind of industrial waste that produced during the causticization process in paper mill. China is one of the papermaking and paper consumption powerhouses. In China, about 50 million tons of paper was produced every year, which means dozens of million tons of lime mud were discharged to the environment. The discharge of such a large amount of lime mud leads to serious environmental aspects including water pollution and land occupation. 2 Therefore, how to recycle the lime mud in environmentally friendly ways is an interesting topic and has drawn lots of researchers' attentions. Lime mud was firstly recovered as soil amendments and building materials. 3 Qin et al 4 have proved that recycling of lime mud as raw materials of anorthite ceramic was a feasible approach to solve the solid wastes. Madrid et al 5 successfully reused lime mud to produce concrete masonry units that with better thermal properties. In recent years,

Carbide slag, as a kind of typical industrial waste, was proposed as a CO2 sorbent in the calcium looping process. The CO2 capture performance of carbide slag was investigated in a bubbling fluidized bed reactor (BFBR) under fluidization conditions. A surface reaction‐controlled kinetic model was employed to describe the carbonation kinetics of carbide slag during the chemical reaction‐controlled stage. The results show that the values of k, tcrcs, and Xu, which respectively denote the reaction rate constant, duration time, and final carbonation conversion in the chemical reaction‐controlled stage, decrease with the cycle number, due to the sintering of the sorbents. The microstructure of calcined carbide slag leads to higher CO2 diffusion resistance in carbide slag than that in limestone, causing lower k and longer tcrcs compared with limestone. The larger BET areas and pore areas of calcined carbide slag provide additional surface for the reaction of CaO and CO2. Therefore, the Xu values of carbide slag are higher than those of limestone after 5 cycles. Reaction conditions have a significant effect on the carbonation process of carbide slag. 850–900 °C is the optimum temperature range for the calcination of carbide slag. The gas‐solid transfer is strengthened at a higher fluidization number, enhancing the CO2 capture of carbide slag. The pores of the larger particles are more easily blocked due to the formation of CaCO3 layer, and the Xu of the carbide slag with a larger particle size is lower.