Urea @ Amazon - Fertilizer Urea, Cosmetics Urea, TieDye Urea

[Photobacterium]

I am getting to the part where I need to neutralize the nitric in the Aqua Regia.

I have looked at many if not most of the AR threads here at GRF. There seems to be consensus that 'it works good' to add a prill (or more) of nitric, before adding the SMB.

First to test for the presence of Nitric. Also, to neutralize it. I think I have seen threads where both applications are discussed.

So ... I need to buy some Urea.


I am reading about farm-grade urea having crap in it. I don't want to jinx myself by using impure ingredients. This is an example of what they have at Amazon in this grade -
http://www.amazon.com/Urea-NH2-46-0-0-Fertilzer-Pounds/dp/B0054PA524/

The Amazon cosmetics grade - $23.60 for a pound - seems pricey. But this part I like - "Cosmetic USP Grade (99. 8% pure)"
http://www.amazon.com/MakingCosmetics-Inc-Urea-17-6oz-500g/dp/B0051UWL1K/

Then there's the Jacquard Urea. For Dying stuff. $8.26 per pound.
http://www.amazon.com/Jacquard-Urea-1-lb/dp/B0009IL24G/

"Jacquard Urea is a humectant, attracting moisture from the air, keeping the fiber damp longer allowing a greater reaction time for the dye. Used with sodium alginate thickener when printing, painting, directly applying procion dye to fiber or is added to procion dye for super intense color." - I wonder if the sodium alginate is part of this variety of Urea ? Hard to tell from the wording - it makes it sound like a separate material.


More Fertilizer urea - I like this because it has identifiable prill-looking things and it looks clean.
http://www.amazon.com/3LBS-Nitrogen-Fertilizer-Urea-46-0-0/dp/B005IAXN2Y/

Anyway, I'm leaning towards the last one but I'm very open to suggestions. I needed to buy some Glycerin and a better scale so I was thinking about getting it all from Amazon.

 

[jimdoc]

You don't need glycerin if its for the sulfuric cell, and you actually don't need urea.

Jim

 

[philddreamer]

Photo, like Jim stated, you don't need urea, but you do NEED to learn to calculate HOW much nitric is required in your AR in order to dissolve the amount of gold that you are processing.
When you learn to do this, the process will be much safer, simpler, faster & cheaper! 8)

Take care & be safe!

Phil

 

[Photobacterium]

Well - Thanks ! - for the info.

I wanted to use the glycerin for the because -
A/ I'm a beginner and
B/ Steve uses glycerin in his video.

It's good to know it need not be used. But I thought I should endeavour to follow the tutorial to a "T" (no pun intended 8) 2 T's in tutorial ) ... in the event I end up coming back here asking for help making the tutorial work.


As far as the Urea for the AR, I went with the 4:1 HCL/Nitric ratio (the muriatic is 31.5% and the Nitric is about 31% - I had to use more water than in Steve's recipe for 50% - my Potassium Nitrate source wouldn't dissolve).

In some of the threads, people describe using a gold bead to soak up excess nitric. Right now the only bead I have is my 0.3 gram "First Bead Ever" - which has sentimental value.

I do have some low carat (10K/ 14K) jewelry I was going to use to learn that process. I could sacrifice one or 2 of them - except in some cases I've gone to great lengths to wash non-gold out using HCL and or Nitric.

 

[philddreamer]

It's good to read that you want to follow the instructions to the "T".
But, the experts @ GRF have agreed that glycerin is not needed, so don't worry about "running into to trouble" because of not using glycerin. 8)

In respect to the calculations that I mentioned, is not just the ratio of acids, (4:1), but, "how much" of the acids is needed, per gram of gold to be dissolved.
Once you learn "how much nitric is needed" per gram of gold, you would add the nitric in increments, (until all the gold is dissolved), so you don't add excess nitric, thus not needing urea. If you don't have a pure button, just adding little extra SMB when you're precipitating the gold, that will take care of you added a bit extra nitric, as long as you didn't go "over board"! :shock:
(To precipitate your gold, you'll need 1g of SMB per 1g of gold expected)

(Hoke states, 4 fl oz HCI (muratic acid) + 1fl oz HNO3 (nitric acid) will dissolve 1 troy oz of gold. This is equivalent to 31ml of HCI + 8ml of HNO3 per gm of gold.)
This is the ratio I use for dissolving my gold.

I hope this helps.

Take care!

Phil

 

[lazersteve]

Phil,

No offense but something looks wrong about your mL numbers. It should be :

4 fl oz x 29.5735296 mL per fl oz = 118.29 mL HCl per ounce
1 fl oz x 29.5735296 mL per fl oz = 29.57 mL HNO3 per ounce

118.29 mL / 31.1 g = 3.8 mL HCl per gram of Au
29.57 mL / 31.1 g = 0.95 mL HNO3 per gram of Au

3.8 mL HCl + 0.95 mL HNO3 per gram of gold to be dissolved.

I round to 4mL HCl + 1 mL of HNO3 per gram adding the nitric acid in increments until the gold is all dissolved up to the calculated amount.

Using a properly covered beaker (watch glass and minimal temperature) refluxing the NOx fumes can reduce the required amount of HNO3 by nearly half in some cases.

Steve