Processing nitric waste before disposal

[g_axelsson]

The copper bar could be covered up by silver and make the cementation process go slower, but except for that you can pick up the left over copper after the silver have cemented out.

If you would hang a piece of copper with a filter bag then you need to keep the copper away from the bag. The silver cementing out could easily grow through the bag and start to cement on the outside of the bag.
Pumping around the silver nitrate is generally a good idea, but you would probably need to circulate it back several times before all silver have cemented out. Cementation takes it's time.

Göran

 

[Palladium]

Don't know how much silver your dealing with, but don't try and reinvent the wheel. The bag idea will only lead to more complications.

[youtube]http://www.youtube.com/watch?v=8UVK18cAeEA[/youtube]

 

[autumnwillow]

Hello, I'm currently in the process of precipitating the copper.



I was able to recover around 2.2kgs of silver, although the quality is a bit low (see picture). It used up around 3 kgs of copper (I guess there is still a lot of free nitric unused in the solution.) When I was hanging a slab of copper on the solution, the silver was coating it, it was kind of hard but can be removed easily by hand (with gloves). I guess I lack pressure on the air pump?



Anyway, back to the copper. I have 2 buckets of copper nitrate, the other bucket is a little dilute with tap water. The dilute copper nitrate's PH is already 2.5, i added a little soda ash to it, the PH moved to 2.9 but when i added the iron scrap nothing happened. Is this normal for a dilute solution? Maybe I should wait a week?

The other bucket is much more concentrated, I am still in the process of raising its PH from 0.6 to 2.5.

 

[butcher]

After using copper to displace silver and other values (palladium if any).
You should use the iron to displace the copper while the solution is still acidic, adding a base before displacing copper makes it harder for the copper ions to gain electrons from the iron, the neutralization and bringing the pH up (to around 9.5 to precipitate metals as hydroxides should be done after the copper is removed from solution.

Copper nitrate can used to generate some nitric acid, adding some more copper (like gold plated copper pins) (you could also add some sodium nitrate if wanted), adding sulfuric acid and distilling the mixture will dissolve the copper leaving gold flakes in a solution of copper sulfate (which can be reused in other processes like a copper cell) the gases from the distillation bubbled into cold water with a little hydrogen peroxide will give a nitric acid solution (see killing two birds with one stone. http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=38&t=6199

 

[autumnwillow]

How long does it take to distill 1 gallon? Would that be economical?

 

[butcher]

Killing two birds with one rock:
With the method I use to make nitric acid, collect gold foils from pins, make up a batch of copper sulfate for use in other processes or uses, (the method I call killing two birds with one stone), can be done in one afternoon, this will not provide a gallon of nitric acid, from a gallon of solution, I cannot remember how much nitric was produced but a quart or two of nitric acid (comes to mind from my bad memory).
Nitric acid to me is valuable, and can be hard to get and very expensive, to buy (or drive to the source paying for the gasoline to get it 250 miles from where I live), the recovered gold for me has value, the copper sulfate is also a commodity I use or do not have to buy...
The time spent was enjoyable, time spent in my hobby, giving me useful products for that hobby, and helping me to add some gold to my melting dish...

Note: For me this method was a way for me to make nitric acid, to recover gold from pins (dissolving the copper), and make a useful byproduct (copper sulfate for use in other processes), leaving me with no waste products to deal with, very economical in my mind...

I can also just make the nitric acid from the nitrate salt and sulfuric acid and distill that, either way the time spent distilling the nitric acid is about the same...

Distilling is a some what slow process as the gases condense in drops at a time, but before long those drops add up to enough of a product to give you a steady supply of reagent for use in the lab, well worth the time in my mind...

 

[autumnwillow]

Well.. its been almost a month now, I don't think the copper is dropping. PH of the copper nitrate solution is 3.0. The iron (jeweller's files) that I dropped were covered with some black metallic crystals. There is a sign of copper but the quantity is very little compared to what I have dissolved in it. Probably about 10 gms of copper is present out of the 3 kgs that I have dissolved. What could have I done wrong? I tried to use a different type of iron (jeweller's old rolling mill handle) but it has the same result with the previous iron that I hanged, black crystals and very small amounts of copper. Take note that I am not using a bubbler, even if I did, the reaction is too slow for the bubbler to have even of any use.

 

[Barren Realms 007]

A bubbler helps with the process to keep the solution agitated and to help the copper release as it build up on the piece of iron being used. Filings are really not a good choice because they get coated too quick with the cementing copper unless there is constant stirring to keep the filling suspended in the solution. An iron sheet would work better than a round bar like a handle.

 

[upcyclist]

Filings are really not a good choice because they get coated too quick with the cementing copper unless there is constant stirring to keep the filling suspended in the solution. An iron sheet would work better than a round bar like a handle.

Just to clarify, he's using jeweler's files, not filings. But since they're jeweler's files, they're still cylindrical and pretty small--especially if they're needle files. For scale: http://www.riogrande.com/Product/Jewelry-Apprentice-Tool-Kit/113963?Pos=6. The 11 files are in the lower-left corner, to the right of the 6 blue file handles.

--Eric

 

[autumnwillow]

I used an iron rod this time. Seems to work better. I'm seeing copper crystals clinging to the rod, not the black ones like what I saw with the jeweler's files. I think it is better to use butcher's method for the treatment of this waste. I think it is more economical and good for the environment though a little more expensive for the fuel costs to distill the waste.

Question, if I distill this copper nitrate liquid and produce copper nitrate crystals, can I convert them to copper sulfate by simply adding sulfuric acid?

 

[rickbb]

Files and other hardened tools are more steel than iron which is what was causing the slow results. The plain iron rod is doing better because it's iron, not steel.

 

[butcher]

Question, if I distill this copper nitrate liquid and produce copper nitrate crystals, can I convert them to copper sulfate by simply adding sulfuric acid?

If you heated a copper nitrate solution (not distilling) you would drive off water from the solution to produce copper nitrate crystals.

Adding sulfuric acid to a solution of copper nitrate basically would not make a chemical reaction, you would just have copper ions, nitrate ions and sulfate ions all mixed in an acidic solution with the hydrogen of the acid.

We can drive off the more volatile liquids from a solution as gases, in the distillation process we can collect and condense these gases, some of these gases (like the NO nitric oxide gas) may need further treatment to make a byproduct (nitric acid) from them depending on the gas.

With the solution in discussion, copper nitrate solution with added sulfuric acid.
(adding some metal copper here would also help to drive the reaction, using gold plated copper pins would supply our copper and we could recover gold in the process).
Water is more volatile than nitric or its nitrate salt, so water will be the first to distill off the solution, as the solution concentrates, then the nitric or nitrates decompose to gases, NOx gas a mixture of nitrogen gases NO, NO2 et cetera.
NO2 gas is water soluble an the gas bubbled into water will make nitric acid.
NO gas is not water soluble, but in air converts to NO2 gas.
If we add some H2O2 to the water the oxygen in solution can convert NO to NO2, which with the water makes nitric acid.
Sulfuric acid or its sulfate are not very volatile, we really have to get the temperature up to a very high temperature before it breaks down and begins to distill off as gases, this is just great here, as we want to keep sulfuric in solution to make copper sulfate, as we distill of the NOx gases to make our nitric acid in the process.

NOX a combination of many different gases of nitrogen and oxygen
NO nitric oxide gas
NO2 nitrogen dioxide gas
H2O water
H2O2 hydrogen peroxide
O2 oxygen
HNO2 nitrous acid
HNO3 nitric acid
(g) gas
--> reaction (=)

some chemical reactions of the gases we are discussing distilling to make the nitric acid.
NO (g) + O2 (g) --> NO2 (g)
3 NO2 + H2O --> 2HNO3 + NO
2 NO2 + H2O → HNO2 + HNO3
HNO2 + H2O2 --> HNO3 + H2O
4 NO + 3 O2 + 2 H2O → 4 HNO3
4 NO2 + 2 H2O + O2 → 4 HNO3

Distilling off the water and the nitrates as gases (to form our nitric acid in the distillation process) from the solution we are left with copper ions and sulfate ions in solution making a solution of copper sulfate.

Read some of the links provided earlier, you may get a better understanding, also there are also a lot of post I have made on nitric acid and its reactions and ways it can be made, searching certain keywords with an author can be helpful, also many members here on the forum have made many different post on nitric and its oxides and reactions or how to make nitric acid...

 

[patnor1011]

I do use CD ROM casing for dropping copper out of waste solution. CD/DVD floppy it does not matter, work for me every time.