General
Risk of corrosion on mild steel structure and equipment in SDA plants is in general negligible, as slurries typical are alkaline.
Slurry containing chloride may appear at certain operation conditions (chloride in process water, absorbent as well as in recycled material), and may course even severe corrosion to structure and equipment when operating the process at unfavorable conditions, also at moderate levels of chloride content.
Critical areas are areas with a wet / dry interface and areas where splashes dry out. “Submerged” areas / equipment may be subject to “pitting” corrosion e.g. behind baffles and the like.
Increasing content of ash in the slurry tends to lower the corrosion problems.
All surfaces of components being in contact with slurry are categorized in two groups: