Apart from the acid production side of the plant we have an arsenic scrubbing and precipitation plant as well. As part of the As precipitation plant we have two large reaction tanks 4.5m dia x 5m high. The solution contained in these tanks is a minus 10% H2SO4 plus 1% Na2S and some calcine solids carry over.
The original rubber lined carbon steel blades just fell off, corroding away at the coated joint to the hub of the shaft.
Subsequent laboratory tests of the following materials have shown none to be appropriate for the job:
304 and 316 SS and most recently 904L. Typical test results show up to 12% mass loss over a two week lab test period.
Has anybody had any experience with a similar scenario and can you recommend another material to try.

Glasslined steel, glass itself, or Hatealloy G may be considered.
The bonding between Steel and rubber/PTFE may fail at 100C althoough at lower temp. it may be O.K.
V.V.Rao