Ferrous Sulfate Storage — Water-Treatment Iron Tank Selection

Storing Ferrous Sulfate? Start Here

Ferrous sulfate is a versatile iron compound used in water treatment for phosphate removal, as a supplement in biological treatment, and even in chromium-VI remediation. If you're handling ferrous sulfate, it's crucial to store it correctly to maintain its effectiveness. This chemical can slowly oxidize over time, shifting from ferrous (Fe(II)) to ferric (Fe(III)) sulfate, which can affect its performance. A well-sealed tank with minimal air exchange helps preserve its original state longer.

Can you store it in a poly tank?

Yes, you can store ferrous sulfate in a polyethylene tank. High-density polyethylene (HDPE) or cross-linked polyethylene (XLPE) tanks are suitable for this purpose, as long as they meet the specific gravity requirement of 1.5 ASTM. However, it's important to use Hastelloy bolts instead of 316 stainless steel due to the specific chemical interactions that could lead to corrosion.

Key Issue: Bolt Material Matters

When storing ferrous sulfate, the choice of bolt material is critical. The combination of sulfate ions and reducing iron can cause rapid pitting in 316 stainless steel bolts. Hastelloy bolts are recommended to prevent this issue and ensure long-term integrity of the tank connections.

The safety that actually matters

• Use tanks with Hastelloy bolts to prevent corrosion.
• Seal tanks well to minimize oxidation from air exposure.
• Match gaskets to the manufacturer chart for compatibility.

Common questions

Why are Hastelloy bolts necessary?

The sulfate and reducing iron combination can cause 316 stainless steel bolts to pit, leading to failure. Hastelloy resists this corrosion.

Can I use a standard poly tank for ferrous sulfate?

Yes, but ensure it is made of HDPE or XLPE with a specific gravity rating of 1.5 ASTM.

How can I prevent oxidation of ferrous sulfate in storage?

Use well-sealed tanks with minimal air exchange to slow the oxidation process.