[paula001]

Hi,

I work as a laboratory technician in a aluminium rod and conductor manufacture.

I wasn't present in the lab when one of the operators put a few dies with loads of aluminium on them to fairly small pot. I assume that they added significant amount of sodium hydroxide and water and left it on the hot plate in the fume cupboard over weekend. When i came to work on Monday, fume cupboard was covered with  white crystals (assuming NaOH) on the inside, there were some crystals in the pot, but also the pot was full of darkish solid.
I was wondering if i can bring it back to a liquid state by putting extra water and heating it up?

What proportion should be used in order to dissolve aluminium from the machine parts using NaOH water and hot plate.

Thanks for help.

[Arkcon]

Start with water and a soft rag, while you wear gloves.  That should be adequate to keep you safe.  If you're the lab technician, you might want to have heavy dish-washing gloves, I usually buy those at the supermarket, when I have serious lab cleaning duties to attend to.  It's very likely that the NaOH has reacted with the aluminum.  It may be pitted, and you may have to scour the surface with an abrasive pad.  But water, maybe a drop of soap when the NaOH is gone, and elbow grease is what you need.

[Enthalpy]

Don't forget the protective glasses!

Do you need some corrosion resistance at the aluminium parts? After this treatment, the behaviour under rain is hard to predict...

Use a motorized metallic brush, after cleaning with much water? NaOH may have corroded the aluminium deeply, then the parts would become too thin once cleaned.

Some pH paper or indicator wouldn't be bad, to check if the NaOH is gone.