Flouride recovery from waste HF/HNO3

[CrankyPants]

I am a production engineer at a hotband stainless steel anneal and pickle line. I am busy optimising the circulation of the acid tanks to mainimise the amount of metal loss and subsequently maximise the amount flouride recovery in the roaster. does anyone work in the same industry that i can bump some ideas off?

We are using 40 000 litre cone tanks. The acid bath circulation pump suction is above the top of the cone at the bottom of the tank. The cone accumulates the metal sludge that have precipitated. At the bottom of the cone is a desludge valve that is sporadically opened to get rid of the sludge. The sludge is full of flourides but sludge wears the pump impellers when it is not kept in suspension.

My idea is to have a separate pump system with the suction at the bottom of the cone that constantly circulates the acid to the top of the tank and thus keeping all the sludge in suspension.

Have anyone ever tried this? Any tips or hints will be appreciated.

 

[mcguire]

Be careful what metal loss you minimize. You may inadvertently maximize defect retention.

Michael McGuire

http://stainlesssteelforengineers.blogspot.com/

 

[cloa]

This metal loss is in a tank not the production line so defect retention could not be an issue.

 

[cloa]

Make posts with links to this one in Corrosion Engineering and Chemical Process Engineering as this sounds too complicated for what is usually in this forum.