Life Cycle Assessment on Resourceful Utilization System of Flue Gas Desulfurization And Denitration with Pyrolusite Slurry

摘要

Reducing the adverse impacts to environment is a more and more important subject in electrolytic manganese industry. Life cycle assessment (LCA) has been a hot tool to measure the type and size of environmental impact. This paper firstly applied LCA on two different processes of producing electrolytic manganese. One process is the resourceful utilization system of high sulfur coal and low grade pyrolusite (the novel process for short) in which high sulfur coal is burned to generate power and emission SO_2, then the SO_2 is absorbed as reducing agent to leach the pyrolusite with 30% MnO_2 grade. The other process is prevalent interiorly, called traditional process where the power is supplied by standard coal combustion, and sulfur acid leaches the manganese ore with 18% Mn grade. Life cycle software converts the original data to nine different kinds of indexes that are able to indicate types and sizes of environmental impacts. Results show that: among nine environmental impacts, the proportion of abiotic depletion potential (ADP) is biggest in both processes, but the value of the novel process is 23.25% smaller pointing the process saves more resource. All the values of other important impacts including GWP, Waste Solids, AP and RI of the novel process are less than those in traditional process. Especially, the value of acidification (AP) in novel process was -2.10×10~(-8) < 0, which means the novel process could control the acidification. In addition, through the composite index, using high sulfur coal in the novel process hasn't bring any more serious impact than using standard coal. Therefore, LCA has provided rational evidence to prove that resourceful utilization system of high sulfur coal and low grade pyrolusite is more efficient and environmentally friendly and pointed which environmental impacts and life cycle links need improving. This paper could provide a reference for further environmental impact assessment of electrolytic manganese industry and an objective basis for decision-making.