Metal finishing Q&As since 1989

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Sodium cyanide

 

Sir,

I want to know how we can determine there is deficiency of sodium cyanide in rochelle copper bath. And method of calculating it to add.

Ajay Aggarwal

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Dilute 10 ml of bath to 100ml with DI water. Add 5 ml of 10% potassium iodide. Titrate to a permanent yellow/white turbidity (the endpoint). Record volume of titrant as T. T x 0.98 = g/l sodium cyanide T x 1.3 = g/l potassium cyanide You probably want to keep the free cyanide concentration in the range of 4-9 g/l.

James Totter, CEF
- Tallahassee, Florida
 

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Wet Analysis to determine sodium cyanide(free cyanide in this case)
pipette [pipettes on eBay or Amazon] 10 ml sample into a 150 ml flask.
Add 50 mls D.I. water.
Add 2 mls of Potassium Iodide Solution.
Titrate with 0.153 N Silver Nitrate Solution to a permanent opalescence end point.
Mls titrated X 0.2 = oz/gal Sodium Cyanide

oz/gal Sodium Cyanide required minus oz/gal figured from titration = oz/gal Sodium Cyanide to be added.

oz/gal needed to be added X tank volume = ounces to add.
ounces to add divided by 16 = pounds to be added.

Terry L Miller