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topic 1193

Water treatment for nickel plating and cyanide


(1998)

A company settled in Turkey-Istanbul in snap fasteners and buckles field.

Looking for a proper water treatment for nickel salts and cyanide.

Any suggestions?

Thanking in advance.

Rifat Karkason
- Turkey


(1998)

Nickel and Cyanide must be separated. Because Nickel-Cyanide complex is very difficult to break down . You can use two stage cyanide oxidation processes for cyanide waste. A conventional heavy metal precipitation using caustic soda works fine with Nickel bearing waste .

Lawrence Chiu
- Hong Kong


(1998)

Here in the U.S., such a system would include a treatment step for destruction of cyanide by alkaline chlorination, a pH adjustment system for the nickel, and then separation of the precipitated solids with a clarifier. The sludges from the clarifier would be treated in a recessed plate filter press. That's not the only way, but it's the most common approach.

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


(1998)

killing Cyanide from silver plating baths

We are using an electroless silver plating bath for our (small volume) production of PCBs containing 1 molar solution of sodium cyanide and 0.1 molar solution of silver nitrate.

Can anybody provide instructions of how to get rid of a few liters of such a used solution (containing also copper). As we produce instruments (pH-meters etc) we can easily control the conditions of the process.

Thanks

Thanasis Ioannidis
scientific instruments


(1997)

1 Molar NaCN = 49 grams NaCN/liter = 6.5 ounces/ US gallon. Alkaline chlorination is NOT recommended for concentrated solutions because of dangerous side reactions like poisonous gases, and eruption. The reaction in dilute solutions is the following formula (reference, Graham's Electroplating Engineering Handbook, 3rd Edition, VanNostrand, New York).

2NaCN + 5 NaOCl + 2NaOH = 2Na2CO3 + 5NaCl + N2 + H2O

In electroplating wastewater, where alkaline chlorination has been used for many years, the cyanide concentration may be only a few hundred mg/liter and the rest of the components of the original solution have also been diluted. Bleach is added, with good mixing, to a permanent blue reaction to Potassium Iodide starch paper [linked by editor to product info at Amazon] as an endpoint, and/or watch the reaction with an Oxidation-Reduction Potential electrode.

Whether your plating bath is proprietary or not, it may be worthwhile to reclaim the silver, and avoid a waste treatment job. Even if you have an exemption to waste treatment due to laboratory status, it is still not a good idea to dump cyanide down the drain.

Perhaps there is someone in your area who reclaims silver from medical film who could take the solution? I don't know if they still use cyanide in the process.

pooky
tom pullizi signature
Tom Pullizzi
Falls Township, Pennsylvania

(1998)

I have read about using 35% Hydrogen Peroxide [linked by editor to product info at Amazon] to treat cyanide.

Unfortunately not much information was given. If anyone knows of the correct process, please let me know.

Thanks.

David Brisbois
Tech-Etch


(1998)

I believe that there may be several patents and/or proprietary processes on the subject. A literature search may give you some leads.


Tom Pullizzi
Falls Township, Pennsylvania

(1998)

I believe that you will find this to be called the Kastone Process. This was a DuPont process, although I am not sure if they are still marketing it themselves.

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


(2002)

Hello!

I need material about minimization of consumer water in the finishing industry for my thesis.

Thank you!

Marta Tocchetto
Universidade Federal de Santa Maria - Brasil - Santa Maria, RS, Brasil



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