Corrosion of Coal Gasification Unit Rod Mill Equipment in Recycling Process of Nitrobenzene Waste Water

The corrosion type, influence range, main medium and boundary conditions of the rod mill of coal gasifcation unit during the reuse process of nitrobenzene waste water were studied by immersion test and electrochemical test in simulated field conditions. The results show that after the coal slurry water source was replaced with benzene nitrate waste water, the rod mill suffered severe crevice corrosion and frequently failed due to the existence of nitrite ion in the nitrobenzene waste water. When the mass fraction of nitrite ion in the nitrobenzene waste water was less than 30 μg/g, the crevice corrosion of 65Mn steel lining plate could be under control. As nitrite ions consumed by chemical reaction during the mixing process in the rod mill, the risk of crevice corrosion in pipelines of equipment behind the rod mill reduced.