Brown solution

[campbellj46]

Not going as planned. I started with 2000g of gold filled material, after 1 liter of nitric acid and .5 liter of distilled water it turned into this brown sludge solution. The material is about 1/2 dissolved.

I'm thinking some of that gold filled material, was something else. Anyone deal with a mess like this? I searched the forums but haven't found anything yet.

 

[campbellj46]

Just for reference, this is some of the material I started with. Most items are marked 1/10-1/20 GF..... I haven't had a solution turn into a brown sludge.

 

[snoman701]

first time running gold filled?

it's iron. as your nitric is exhausted it drops out of solution as ferric iron. Adding a little sulfuric does the trick. not much, just a bit

 

[snoman701]

I sincerely hope you didn't start with 2 kg of gold filled in a beaker. if so you are going to be really frustrated and I'd recommend getting that iron in solution, decanting, then removing 3/4 of the gold filled and putting it to the side.

 

[campbellj46]

first time running gold filled?

it's iron. as your nitric is exhausted it drops out of solution as ferric iron. Adding a little sulfuric does the trick. not much, just a bit

It's my 3rd run of GF material usually I process 14-18k nuggets and Placer gold from my operations.

Thanks for the reply. I decanted the "Rust mess", and it turned green the 2nd addition of nitric and distilled water, cleaned it up to what I'm used to seeing

Ended up with 2000ml + of this iron solution. I'll let it settle out, wash the sediment and process it for any values.

I usually do process 2 kilos at a time in a 5000ml beaker and seperate and wash in 2000ml beakers.

 

[campbellj46]

It's taken 2 weeks to get this far, getting rid of all of the iron, waiting on it to settle out but there's a lot of gold in there. 1st refining in AR, it's been settling for a couple of hours.

 

[campbellj46]

That is 1 big gold sponge, holy mackerel I'll be washing it and getting the chemicals off in the morning

 

[silver1]

Get a 5 gallon stainless pot to run your GF in. Your glassware will thank you!

 

[snoman701]

Get a 5 gallon stainless pot to run your GF in. Your glassware will thank you!

Interesting...I've done this once and I ended up with the ferric iron caking up and trapping gold. It was a mess. I swore off stainless pots for gold filled at that point. But that was before I had figured out the sulfuric trick as well.

Nobody trusts me on it. But it works wonders.

 

[campbellj46]

Thanks but I prefer using pyrex glassware. I can see what's happening inside and not worry about pitting in the stainless. I've had bad experiences with cheaper made stainless.

On a good note... totals are in. 171.6 grams or 5.46 Troy oz. The only problem so far, i need some more glass vials, or start melting some bars.

 

[Zhazham]

first time running gold filled?

it's iron. as your nitric is exhausted it drops out of solution as ferric iron. Adding a little sulfuric does the trick. not much, just a bit

I have a small problem with iron. Have maybe 300 ml of solution with 15-20g of iron. Solution has some silver in it with gold foils and flakes. Would like to clean up iron to get valuables out. I added small amount of silver in to solution to use up possible nitric. Im thinking of adding sulfuric as suggested, but i don't know how much. I have 96% sulfuric but not much experience of sulfuric, especially this strong. Sure i will do it carefully by tiny amount at the time but still wondering.

 

[campbellj46]

I have a small problem with iron. Have maybe 300 ml of solution with 15-20g of iron. Solution has some silver in it with gold foils and flakes. Would like to clean up iron to get valuables out. I added small amount of silver in to solution to use up possible nitric. Im thinking of adding sulfuric as suggested, but i don't know how much. I have 96% sulfuric but not much experience of sulfuric, especially this strong. Sure i will do it carefully by tiny amount at the time but still wondering.

The values are going to be cemented out in the bottom of the solution. The iron present, would have cemented out everything, copper, silver, gold, other PMGs.

How I got mine out, I let it settle for a while, about a week. I siphoned off the solution without disturbing any sediment on the bottom. I had 2000 ml , I siphoned off down to 150-200 ml of solution, leaving everything on the bottom.

The remaining solution, I boiled until dry. I put it all in a melt dish and heated with a torch to oxidize the iron, not hot enough to melt any. Once it was oxidized, I repeated the process of nitric acid boils to remove the iron oxides using diluted nitric acid. Wash, rinse, repeat until nitric boils were clear.

That took about 4 days, slowly repeating the steps until I was left with a clear solution and gold foils/powders/sediment. Then went to aqua regia, refined it twice in aqua regia for the final result.

 

[Zhazham]

Actally, that sounds like an option for me too as the volume of solution and amount of iron is quite small. It's been settling over a week now at my "summer" cottage. Maybe ready to dry out when i get there next time.

Right after solution had cooled down a bit, i siphoned some clear solution from top of the beaker and tried cementing with copper. Nothing much happened. Probably, like you said, silver was already cemented out.