Citric acid weirdness

[chunkolini]

For a few years I have been using citric acid to remove mill scale from hot rolled mild steel strip very succesfully. I soak it over night in a plastic tube full of solution and take it out in the morning . the solution goes green and the scale is left as a blackish deposit.
My new workshop takes it water from a borehole that I am told is contaminated with iron, the water does leave an orangey colour when it drips into the sink.
Yesterday i took a load of bits of strip out the soak, they came out fine, but the solution is full of a white chalky precipatate. Anybody got any idea of the chemistry involved?
No desperate need to know just curious.

 

[Parm]

At a guess it's likey to be some sort of Calcium carbonate / limestone material, I'm sure some one will be along shortly to correct me

 

[TechnicAl]

Might be Iron Hydroxide rather than just the oxide
Citric Acid is C6H8O7

 

[voipio]

Citric acid is capable of chelating, or forming a complex with a variety of metals, including iron. Iron citrate is white and poorly soluble, and it is highly probable that iron (II) citrate, or a chelate complex, is a major component in the white suspension you see in the solution.

 

[gordon stephenson]

Never mind all that Chunko, Does it still get rid of the mill scale the same as before?