Weak sulfuric acid

[kootheBUNNY]

What material is more suitable for weak sulfuric acid? we are currently designing a coagulant mixing tank. Our coagulant, which is ferric sulfate, will be mixed with 98% sulfuric acid. Initially, we decided to use carbon steel coated with enecon as our tank material. Is it okay to use SUS316 for this? How about FRP? Or are there other more suitable materials to consider? Would like to ask for your opinion. Thanks!

 

[shvet]

Describe process in details

for info

https://www.eng-tips.com/viewthread.cfm?qid=512266

https://www.cheresources.com/invisi...water-treatment-plant-industries/#entry130276

 

[pierreick]

Hi,
Consider this document, Q/A ! originally from Dupont , not sure.
Pierre

 

[hacksaw]

You don't want 316 in the presence of chlorides at low pH,
properly designed FRP is a good bet

 

[dik]

A bit of a caution, I suspect sometimes that chemical properties of weak acid may be different than that of concentrated acid.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[kootheBUNNY]

@shvet, we are in the process of designing a wastewater treatment plant. One of the reagents needed for the process is coagulant, ferric sulfate. Ferric sulfate will be mixed with 98% sulfuric acid in a 2m3 mixing tank together with water. As I have stated above, we initially decided to use carbon steel coated with enecon. Would like to know if there are other material that is more suitable to consider for this. Thanks!

 

[YungPlantEng]

Haha I had a project on modifying one of our systems to produce ferrous sulfate.

FRP is viable depending on what you’re mixing. Lined tanks are appropriate for this service with the same issue on abrasion. If I had to go through this again I’d go overboard and clad it in C276 or try FRP. Unless you’re using very clean raws you can expect heavy chlorides impacting the process.

 

[shvet2008]

@kootheBUNNY
This is the brief description, not detailed one. Not enough info provided.
For your info - depending on particulate conditions I have long-term positive experience with H2SO4 and sulfate environment in contact with CS, SS, glass-lined, PTFE-lined, lead-lined, acid-proof brikcs, rubber-lined and some others. Sure conventional plastic like polyolecins and some cheap coatings have potential being considered too.

You may choose most appropriate one from list above by yourself.

I recommend you to still describe process in derails to obtain a valuable and comprehensive advise.

 

[georgeverghese]

What is wrong with ferric sulphate as the coagulant - why bother with converting it into ferrous sulphate?

The ferric ion is more polarising than the ferrous ion so it ought to be more effective at destabilising suspensions ?

 

[pierreick]

Hi,
Normally ferric sulfate solution is ready made, check with the supplier and company in charge of treatment.You don't have to add sulfuric acid. My experience in China is to use PE storage tank with dike.
Safety should be one of your concern.
Pierre