r/ChemicalEngineering • u/equilrxnlab-Mfr • 9d ago
Chemistry Looking for advice on corrosion-resistant materials for pilot reactors
Hey folks, we’re setting up a small pilot chemical processing project and I’m looking for advice on materials for the reactors and vessels. The process has three main steps: neutralizing inorganic acids with alkali (pH 8.3–9.0) to get solid precipitates, reacting the filtrate with mineral additives at room temperature with stirring to recover secondary solids, and then evaporating and crystallizing the liquid phase to get the final salts. Since every step involves acids, corrosion resistance is a big concern. Has anyone done something similar? Would stainless steel work, or should we go glass-lined, titanium, or something else? Appreciate any thoughts!
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u/Which_Throat7535 8d ago
Look into high-nickel alloys from Hastelloy. These are generally some of the most corrosion resistant alloys available; and they’re going to cost you. You’re going to have to do the leg work, though; there is lots of corrosion literature out there on how various alloys perform in certain conditions and environments.
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u/equilrxnlab-Mfr 8d ago
Yes, I understand that Hastelloy can resist corrosion, and indeed, as you said, the cost will be higher.
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u/Substandard_eng2468 8d ago edited 8d ago
What's the temp and pressure range? Volume? Solution components? Are there chlorides?
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u/equilrxnlab-Mfr 8d ago
Our solution contains hydrofluoric acid, with a maximum temperature of 160 °C.
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u/DarknessHeartz 8d ago
Then you definitely want to look at very special materials, because according to the Graco chemical compatibility chart, you're only left with PTFE or PVDF. But your temperature is very concerning for such materials as well. What pressure and HF concentration are you looking at?
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u/EquilibriumReaction 8d ago
Hastelloy is a good option. You may also choose a reactor with an inner PTFE coating, but it cannot be used under vacuum conditions, as the coating may peel off or blister. In addition, the temperature should be controlled below 130°C, since prolonged exposure to high temperatures may cause the coating to decompose.
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u/DarknessHeartz 9d ago
It depends a lot on the acid/alkalis itself. Stainless could work, but also not. The same goes for plastic (PP, PVC, PVDF, etc.). PFA lined CS may be good too. Check some corrosion resistance/chemical compatibility tables for a quick initial screening.