TG-FTIR and Py-GC/MS combined with kinetic model to study the pyrolysis characteristics of electrolytic manganese residue

•Pyrolysis of the EMR was studied by TG -FTIR and TG-GC-MS.•The TG-FTIR results indicated the formation of H2O, NH3, CO, CO2 and SO2 during the pyrolysis.•Kinetic triplets (E, A and f(a)) were estimated by FWO, KAS and master-plots methods. The manuscript used TG-FTIR, Py-GC/MS along with kinetic models to investigate the pyrolysis characteristics of electrolytic manganese residue. The possible reaction mechanism for the pyrolysis process of electrolytic manganese residue and the change rule of volatiles release characteristics during the pyrolysis were analyzed. The result shows that the pyrolysis process of electrolytic manganese residue can be divided into five processes: the dehydration of CaSO4·2H2O, the removal of ammonium salt compounds, the transformation of anhydrous CaSO4 crystal form, the decomposition of carbon-containing organic matter and the solid-phase reaction between the substances to form a new phase. According to the difference of activation energy values, the kinetic process for the pyrolysis of electrolytic manganese residue was divided into four sections. The pyrolysis reaction mechanism functions for different kinetic mechanism were the second-order phase boundary chemical reaction function: g(α) = (1-α)−1, Mampel Power law function g(α) = α1/4, 2/3-order phase boundary chemical reaction function g(α) = (1-α)-1/2 and three-dimensional diffusion function g(α) = [1-(1-α) 1/3] 1/2. The major gases released during the pyrolysis of electrolytic manganese residue were NH3, CO2 and SO2. The intermediate product of CO was unstable and participated in the reaction to promote the formation of CO2 and SO2.