Newbie, few ?s

[Duxthe1]

First off, great forum, that I recently found again without realizing I had already registered years ago. I'm a prospector and as such I'm looking to process placer gold but wanted to get more aquainted with scrap recovery first. I'm looking to use the AR method similar to whats described in Hokes book. So I went to the chemical supply house. I was able to buy fuming Hydrochloric acid and I beleive its 35%. I was only able to buy 10% nitric. Since I'm shooing for a bout a 3:1 and the Nitric is about 1/3 the stregnth of the HCL then I'm thinking to mix them at a 1:1 ratio. Will that work, or is there other hidden pitfalls of having such dilute Nitric? My ASSumption is that I'll end up with a dilute AR. Am I wrong or should this work?

I also picked up some sodium nitrate to use as a precipitant. The section in Holes on Sodium nitrate was breif, are there any other pointers for using this precipitant. I have some amonium nitrate (urea?) in pure prill form, but i've read conflicting opinions on using it, care to rehash an old subject for a newbie?

Thanks in advance for the help.

 

[seawolf]

Welcome to the forum. I would go to Lasersteves site and watch the videos on the AP method rather than starting with the AR method. (Lots of posts where the AR does not work well) Also the videos on stannous chloride, you will need it often. Search for AP method for a lot of info. Start slow and work up, this is a great hobby but not one that will make you rich in a short time.
Be sure to read the saftey section.
Work safe and be safe, Mark

 

[Geo]

you can concentrate nitric acid with the reflux method.

 

[Duxthe1]

Thanks for the replies guys. At this point I'm already invested in the AR method and would like to gain experience with it. I can appreciate easier but am not looking for easy money or getting rich refining PGMs. Rather practical experience that I can apply to another hobby, recreational placer mining.

While I have read up on methods of concentrating nitric, I'm really wondering if I need to? IS there any pitfall to making AR with diluted Nitric? I've read that diluted AR is better sometimes in that it is more selective for gold. All of my reading though has implied that you take full stregnth AR and dilute it. Any reason you can't make it "diluted" to start with?

 

[Geo]

not sure about the selective part. i think AR will dissolve most metal regardless of concentration but stronger acid means a more vigorous reaction. i wouldnt make a ratio solution of AR but rather start out with hcl acid and add nitric in small increments over a period of time to reduce the chance of free nitric which will have to be neutralized before precipitating. its more economical that way for time and money.small batch = small increments, large batch = larger increments.

 

[Harold_V]

While I have read up on methods of concentrating nitric, I'm really wondering if I need to? IS there any pitfall to making AR with diluted Nitric? I've read that diluted AR is better sometimes in that it is more selective for gold. All of my reading though has implied that you take full stregnth AR and dilute it. Any reason you can't make it "diluted" to start with?

It is my opinion that you can use the 10% nitric with very acceptable results. As you alluded, the ratio would be different, but should yield the same results if you can work out the correct ratio.

The notion that concentrated acids are more effective isn't exactly true. If you'd like to see evidence of that thought, try dissolving some silver with 68% nitric, then notice the difference when you add water.

Harold

 

[Joeforbes]

Hoke makes mention to using sodium nitrite as a precipitant for gold, not sodium nitrate.

Bondie Stump Remover is made of sodium metabisulfite. Lowe's would carry it, if you have one near by. It is a very effective precipitant.

Please note: sodium metabisulfite works by supplying a source of SO2 gas to precipitate the gold. SO2 is God awfully foul and toxic. Do it outdoors or in a fumehood.

 

[Duxthe1]

good catch, I even wrote it wrong on my shopping list.

edit: I picked up some Bonide "Stump Out" this PM at Home Depot, ugh I hate shopping there but my shop is literally connected to their parking lot. I paid less than 6$ for 1lb

 

[Joeforbes]

Yeah, it's not too bad considering how much gold it can precipitate.

Refiningchemicals.com sells 50lb bags for $110 (that includes shipping). You might want to check them out for chemicals if you plan to refine regularly. Don't order the 1 gallon nitric acid from them though.. the container they ship it in is dangerous at best. The 5 gallon containers could double as bomb shelters though, and are a great price ($190 something including shipping).