Q:  I’m running a lithium extraction process where a mineral called spodumene is roasted in a mixture of sulphuric acid (95-97%) at at about 150°C to form lithium sulfate. I’ve to use Hastelloy C276 for some process equipment but I’m still experiencing corrosion. Please help.

A:  Hastelloy C276 bolts typically work well in sulfuric acid but not at this temperature and concentration. Normally the max operating temperature for Hastelloy C276 at with H2SO4 at 97% concentration would be around 70C. For these conditions of sulfuric acid, I would suggest to go with tantalum metal fasteners. Tantalum is the most corrosion resistant option available to industry. It is very capable of handling sulfuric acid at any concentration 150C.