Waste related Problem

[mikelugg]

Hallo and thank you for the chance to particiupate in such a great Forum,
-and this is my first time.
I have read 4Metals Post on Waste treatment which was a great inspiration
for me to become more conciencious about what I am doing.
I am here in Germany and what I am doing is deplating silver cuttlery with Nitric, after which I cement
the silver with Copper.
The used up solution after the silver has dropped, I have to discard.
I have no need to recover the Copper, so I just would like to drop out all
the dissolved Metalls from the solution after cementation of the Silver has finished.
I got myself the Sodium Carbonat and the Sodium Hydroxide as mentioned in 4 Metals Post,
where he recommends lowering of the Ph to 2,5 with Sodium Carbonate and dropping the Copper
with Steel bars. After filtration of the Copper he recommends dropping the Ph further with NaOh to
around 7 where the Iron then precipitates.
Now I have got one question.
Can I just skip the Copper filtration part, get the Ph down to 7 in one go,
and precipitate the Copper together with all the other non precious metals remaining in the solution.
Then I would go on to let everything settle in my container, siphon off the liquid, and collect the sediment
once enough has built up.
Does anyoned recommed a procedure for this?,
or is this at all possible like this?
I am glad for any comments.
Cheers.

 

[niteliteone]

Mikelugg
I'm just shoting from memory so I might not be completely correct with this. :?:
Copper in solution (copper nitrate) is very poisonous and bad for the environment. Therefore it must be removed from solution before disposal.

To do as you suggested and "not" drop it with iron but just neutralize the solution to remove the copper will not work. Most of the copper will stay in solution way past the greater than neutral ph of 11 or more :?: . Not safe to dispose of.

It makes more sence to just replace the copper in solution with iron (not poisonous) 8) and then neutralize the remaining solution to a ph of 7, that will safely drop the iron from solution, leaving you with a safe salt water that can be disposed of easily.

Anyone please correct me if I have made a mistake.

Tom C.

 

[mikelugg]

Thank you for your comment.
The reason why I was asking is the following.
When I put my Iron in the Copper Nitrate Solution, the Copper seems to plate on the Iron rather
than to just drop to the bottom of the container. So now I have read that I have to dillute the Solution in order
to let the process go into the desired direction.
Can this be so? How much must I dillute?
This would actually be my next question.

 

[eeTHr]

Mike---

As you become accustomed to how much copper will be dissolved when cementing your silver, you can start with around 75% of that as copper powder which you have recovered in your waste disposal process, then suspending solid copper to finish the cementing once all the powder has gone into solution.

This will present more surface area to the silver nitrate, speeding up the cementation process, and also allow you to save on copper purchasing. To prevent accidental incomplete dissolution of the copper powder, don't cement all your silver nitrate in a single batch, but same some to add to the cementation process, just in case your estimate is off, and some powder should remain in the bottom with your cemented silver.

You can also use the powdered iron to make ferrous sulfate crystals, which would come in handy if you ever dissolve gold.

 

[Geo]

metal does not "plate" without an electric current.it may adhere tightly but if you let the reaction finish until the solution is a very pale green and theres black powder in the bottom of your container you remove the piece of steel and let it dry and any cemented material will flake off.

 

[butcher]

Geo, I thought many of these processes like cementation were more than just a chemical reaction,

and I see them as an electrical-chemical reaction, and I have believed these can plate out of solution even without an external power source.

Am I wrong in my thinking? and why if so.

 

[Geo]

the act of plating is an electro-chemical reaction.ive read that without an external electrical source no plating can occur.without electricity its called "coating".let me find some references for this,but i wouldn't have said it unless i was sure i have read it in studying.besides to have electron movement or an electrical current you have to have a circuit where electrons can travel from + to a -.

 

[butcher]

how does electroless plating work?

 

[Harold_V]

Geo, I thought many of these processes like cementation were more than just a chemical reaction,

and I see them as an electrical-chemical reaction, and I have believed these can plate out of solution even without an external power source.

Am I wrong in my thinking? and why if so.

You are not wrong. The process if cementation occurs because of an electron transfer. The process is well known and used in the plating industry---primarily for electroless nickel.

Harold

 

[butcher]

Thanks, because I have discribed the process, using the terms "plated out of solution", and want to use the correct terms if I possibly can.

 

[Geo]

ok.electroless plating is mainly used to plate non-metallic material such as you would find in ceramic IC's where the gold is plated right to the ceramic another example is dinnerware (plates and saucers and cups) which are porcelain and odd shaped objects that need a uniform thickness in deep recesses.i concede that you can plate without a direct current.I've never thought of cementing as (plating) because the metal is not really attached in a way you would expect something plated to be.

 

[Harold_V]

All processes are electrical in nature---swapping of electrons.

I'm well beyond my field of expertise in this subject, as I am not, nor have I ever been known to work as, a plater, but it is my understanding that electroless nickel can develop properties superior to those that are applied with a rectifier. It is not limited to plating non-metallics, by the way.

GSP has considerable experience working with plating, so perhaps he can enlighten all of us.

Harold

 

[mikelugg]

Thank you for commenting and for the advice.
Something is off with my Copper Nitrate Solution, and it seems that I can not drop the Copper out of it.
The process that I am using dissolves a lot of unwanted
Copper Nitrate together with the Silver from the Plated Cuttlery.
I simply dip the plated items in Nitric and quite a bit Copper dissolves with it.
The process releases quite some heat which evaporates the water from my
Nitric Solutions.
I am not sure if dilluting with the same amount of water before cementing the Silver with Copper
can be enough.
Adding more Copper in the cementing process makes for a thick green liquid.
After cementing the Silver the solution is never blue in color as suggested.
It stays dark green, but the Salt solution test shows that there is no more Silver in it.
I am then raising the Ph with Sodium Carbonate to 2,5
but when I add my Iron no Copper falls out of Solution.
Just the Iron gets a red Copper coating.
How does the Copper look that has to precipitate?
I am using Iron that is galvanised with Zink. Can this be the problem?
Any suggestions would be appreciated.

 

[Barren Realms 007]

Thank you for commenting and for the advice.
Something is off with my Copper Nitrate Solution, and it seems that I can not drop the Copper out of it.
The process that I am using dissolves a lot of unwanted
Copper Nitrate together with the Silver from the Plated Cuttlery.
I simply dip the plated items in Nitric and quite a bit Copper dissolves with it.
The process releases quite some heat which evaporates the water from my
Nitric Solutions.
I am not sure if dilluting with the same amount of water before cementing the Silver with Copper
can be enough.
Adding more Copper in the cementing process makes for a thick green liquid.
After cementing the Silver the solution is never blue in color as suggested.
It stays dark green, but the Salt solution test shows that there is no more Silver in it.
I am then raising the Ph with Sodium Carbonate to 2,5
but when I add my Iron no Copper falls out of Solution.
Just the Iron gets a red Copper coating.
How does the Copper look that has to precipitate?
I am using Iron that is galvanised with Zink. Can this be the problem?
Any suggestions would be appreciated.

Are you diluting the concentration of your nitric to 30-35% with distilled water before you use it deplating the item's? The greenish color you describe indicates you migh still have silver in your solution. You might want to take a small test sample of your solution and add a drop of HCL to it and see if a cloud forms indicating that there is still silver in the solution, the HCL will tell a better story than the salt. You might need to increase the surface area of the copper you are trying to cement your silver with, a little heat might help as well.

 

[Palladium]

I haven't done any plated silver items, but if your base metal is copper and your dipping the item in nitric to remove the plating seems to me when you dip and remove the item some of the silver is probably plating back to the copper..

 

[mikelugg]

Thank you Barren Realms 007.
I have already made a plan for next time to increase the surface area of my Copper.
I am not dilluting down to 30 %, I fear this would then take too long since every peace has to be hand dipped
and I do not want to dissolve the whole item but just get the Silver coat off.
But I sure will give it a try to dillute my Nitric, aswell to save cost. But then again it takes me quite some time to strip 5 kg
of Spoons and Forks which yields just a few ounces of Silver. So I need to be fast.

 

[Barren Realms 007]

Thank you Barren Realms 007.
I have already made a plan for next time to increase the surface area of my Copper.
I am not dilluting down to 30 %, I fear this would then take too long since every peace has to be hand dipped
and I do not want to dissolve the whole item but just get the Silver coat off.
But I sure will give it a try to dillute my Nitric, aswell to save cost. But then again it takes me quite some time to strip 5 kg
of Spoons and Forks which yields just a few ounces of Silver. So I need to be fast.

You can dilute your solution down to 15% with it in a 5 gal plastic bucket and then set up another 2 gal bucket with your material in it to be dipped into your 5 gal bucket. Adding heat will help the reaction. You can take your container with the material in it and soak it in distilled water to help remove any silver that cemented back onto the material and wash the copper/silver nitrate off. You can then add this liquid to your original 5 gal bucket. Filter all of your solution. Then add heat and evaporate your solution down to 1/3 of it's volume or till crystals form in your solution when it cools, add some distilled water to redissolve the crystals into your solution. You can then use the copper of your choice and cement out your silver from the solution.

 

[mikelugg]

Thank you Barren Realms 007.
I trust you have tried it that way.
I did previously try a set up like you mention, but the reaction becomes too fast to handle.
So reducing the Nitric strenght is the key there.
Thank you very much for helping me this step ahead.
I am always trying out new things you know, so be sure, I will test this method.
I am actually finding just enough cheap material to process about 20 kg plated cuttlery a week.
But finding a speedier method sure helps.
Just now I am stuck with this waste disposal problem.
I want to be responsible enough to fix this problem before I proceed to more volume.
I sure would appreciate some advice from you regarding this issues that I have with my Copper precipitating
problem as I have mentioned it in the beginning this Post.

 

[Barren Realms 007]

I have done small batches like this will some success. You will have a constant battle with the silver trying to cemen back onto the material. I generaly save any plated material for cementing silver out of solution from processing sterling. I have not had the problem you seem to have with steel dropping the copper out of my solution.That could be one of the problems that will be fixed when you dilute your nitric. Soda ash is what I use to neutralze my solution once the copper has been removed.

 

[butcher]

I really do not think the process will work very well unless you dissolved the whole fork or spoon in nitric acid (which would be a huge waste of nitric for a few cents of silver), as palladium said the silver just plates back onto the spoon, until all of copper is dissolved.

You may get a trace of silver, but your wasting your money, and generating waste, risking your health, for nothing.

Take the money go buy some scrap sterling silver, then try the process, forget the plated forks and spoons unless you just want to resale them.