Reductive roasting of low-grade pyrolusite by rotary kiln and kinetics of tail-gas resource utilization

The reductive roasting of low-grade pyrolusite by rotary kiln and kinetics of tail-gas resource utilization were investigated. The results show that the manganese reduction efficiency is higher than 98% at the roasting temperature of400 ℃ for 120 min when the addition of concentrated sulfuric acid is 1.5 times of the stoichiometric amount. As for the tail-gas resource utilization by low-grade pyrolusite pulp, the leaching efficiencies of the first and second stage are98.60% and 98.61%, respectively under the conditions that the ratio of solid to liquid is 6:1 and the adsorption temperature is 80 ℃. According to the kinetic model of the tail-gas resource utilization, the apparent active energy is16.04 k J/mol. The technology can realize both high reduction efficiency of low-grade pyrolusite and fully recycling use of tail-gas by low-grade pyrolusite pulp. The eco-innovation about this technical process is characterized by high manganese reduction efficiency and cyclic utilization of sulfur resource in tail-gas, providing some references and judgments for the high utilization of low-grade pyrolusite in industrial scale.