Nitrate cell

[OMG]

I am not too familiar with nitric acid yet, but I am interested in setting up a cell with a nitrate electrolyte. I am assuming that if the electrodes are resistant to nitric acid, then the cell should evolve NO2 from the cathode as the metal deposits. Does anyone have a suggestion for a good (reasonably inexpensive) metal or alloy that can resist nitric acid in this instance?
My idea is to use nitric to dissolve base metals, then use that as an electrolyte, and pull out the NO2 and use those to regenerate nitric.
Thanks

 

[Anonymous]

OMG, I made a cell with KNO3 as the electrolyte. I split the cell and put the cathode in one cup and the anode in another. I used a piece of filter paper for a bridge. My anode was fingers and such that I just melted into an anode. My actual gold amount was small but I liked the results.
The base metals were acted on by the NO3 ion and go right into solution then migrate over to the cathode where they run into my guess is the KOH formed there and are precipated out as a super fine powder, the gold is trapped on the anode side becuase it does not go into solution
and when the base metals are reformed into the powder at the cathode then can not go back because the particals can not go through the filter.

I recovered a very tiny amount of gold (my anode was only from 3 grams of melted fingers & pins. I just did not have enough material to weight the end result to compare recovery.

I wanted to use it to seperate the silver, so I placed a little regular salt also in the anode cell which made the silver chloride form but my gold particles were practically inseperable from it.

More experimentation is in order.

Jim

 

[OMG]

Oh I see. You were purifying your gold anode by dissolving all the base metals in it. If I were you I wouldn't put any chloride (or any halide for that matter) into the cell. The chlorine might take over the electrolysis and you might end up dissolving the gold.
So in your experiment did any gas come off the cathode? (ie nox, hydrogen)
What voltage were you running at?
My idea was to actually recover the NOx gas from dissolved nitrates in order to regenerate the nitric.

 

[Anonymous]

I use 6v batteries - storage type from emergency lights that I replaced at one of my resturuants - I am the Maint man - I recharge the batteries with the charger from the lights - cost me only some electric.

I did not notice any gas at the anode, but there was gas at the cathode, I did not test to see what it was, just assumed it was hydrogen from the water.

Now, I run the cell with the below proceedure
Anode cell was KNO3 and water only -
Cathode cell was KNO3 with about 1 part per 50 of NaCl, which I tried to match with the expected amount of silver.
I do not use chloride for when processing for gold only, I use chloride addition when running silver electrical contacts to seperate the silver from the other stuff. This one one thing I learned from the original experiment were I used a small amout of chloride to scavenage any silver because I was not sure of the content. I also in my orginal experiment had the chloride in with the anode, I do not do that now.

My main purpose was to be able to get silver from electrical contacts because I get them every day at work. I however only get small amounts of gold content items that I mostly overpay for on ebay, just for the learning experience and fun of getting a little gold.

I think that if you inquart with copper, you could use this for your primary
gathering of the gold, then use better proceedures for your concentrated
gold powder fromt the anode cell.
KNO3 goes right through filters which is nice.

Jim

 

[Anonymous]

I should add that when I tried without the filter between the cells, everything in one cup, it worked intially but you could actually watch the powdery metals that form at the cathode be carried over to the anode by the flow of water or ions, do not really know but once they got over and surrounded the anode, everything basically shut down, I do not know if it was from shorting the cell or if the fine metal particles reacted with the nitrate far easier than the anode, possible conbination of both.

I use filter paper that is made for filtering deep fat fryer grease, it is fairly thick and felt (cloth) like.

Jim