# Urea



## rusty (May 22, 2013)

The liquor was evaporated with hydrochloric acid additions to noxx out the nitric. I use urea to test for free nitric, from the teaspoon full of urea you will observe the reaction the pot on the left had no reaction - job well done.

The pot on the right had a vigorous reaction to a teaspoon of urea. The reaction shows me that I still have to improve on my skills.

Use this information at your own risk :twisted: :twisted: 

[youtube]http://www.youtube.com/watch?v=OujHaEl3XoI&feature=em-upload_owner#action=share[/youtube]


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## rusty (May 26, 2013)

I keep a quart or two of urea handy in liquid form, for those who are wondering about DEF this is 32% urea in distilled water so it will work fine and has an indefinite self life should it crystallize just add more water to bring the urea back into solution.

The urea I have came in large cemented chunks which would not feed through the farm machinery spreading it onto the fields. The fertilizer plant was going to discard it.


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## MEANIE (May 26, 2013)

WE use about 100,000 lbs of urea prills a week to make cow feed at my work. Theres a lot of uses for urea.


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## alexxx (May 26, 2013)

A few question regarding urea when added to AR to remove free nitric

- Is it absolutely necessary to reduce to a syrup and deNoxx with HCL prior to any urea addition? 
- A solution of AR can be still reduced to a syrup and deNoxxed with HCL after urea addition ?
- Can someone only add urea to remove free nitric from AR ?
- After several additions of urea into AR, when the urea is no longer fizzing, what if the AR solution is fizzing when adding a pinch of smb (does it means there's still free nitric ) ?
- Is it possible to add too much urea to an AR solution ? Will that interfere with smb precipitation ?

cheers,

Alex


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## rusty (May 26, 2013)

alexxx said:


> A few question regarding urea when added to AR to remove free nitric
> 
> - Is it absolutely necessary to reduce to a syrup and deNoxx with HCL prior to any urea addition?
> - A solution of AR can be still reduced to a syrup and deNoxxed with HCL after urea addition ?
> ...



Alex it is preferable to evaporate, I used a teaspoon full of liquid urea checking on my work, as you see from the video the pot on the right had not completely expelled the free nitric.

The next time your doing an evaporation keep a watchful eye on the solution, soon after the heat is applied you will notice small bubbles escaping right down to syrup. Then when you add fresh HCL same thing, if you used to much nitric the bubbles coming off will remain vigorous until you reach the syrup stage.

With each evaporation the bubbles will lesson up, when the de-noxx is complete the surface of the liquid at syrup stage will be very calm for a minute or so, then it starts bumping this is when I add a bit more HCL also looking for those telltale bubbles. 

That last addition of HCL is used to cool the liquid stopping the bump as I turn off the heat.

The small addition of urea at this point was only to check on my work, soon I'll be able to rely on experience.

Free nitric is going to burn up a lot of SMB, or copperas. It has been said to much nitric when adding copperas in abundance will cause a boil over.

When I add SMB powder it floats on the surface gradually sinking.


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## Charles Connor (Jul 5, 2013)

When I have the AR I add the urea in solid form, thats the way i got it, i get the same reaction of your right pot in the video, the way i do it i have never get any solution into syrup and i alway get the ammount of gold espected so in my opinion there is no need to get it into a crust...


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## Lino1406 (Jul 8, 2013)

SMB will fizz also with HCl - producing SO2.
Besides all what was said about urea, it also
annihilates chlorine, so enabling no choking
work.
Lino1406, author "30 recovery procedures..."


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## AndyWilliams (Jul 8, 2013)

alexxx said:


> A few question regarding urea when added to AR to remove free nitric
> 
> - Is it absolutely necessary to reduce to a syrup and deNoxx with HCL prior to any urea addition?
> - A solution of AR can be still reduced to a syrup and deNoxxed with HCL after urea addition ?
> ...



Alex,

To remove free nitric from AR, I filter and then add gold to the solution. It eats up the rest of the nitric. Just keep note of any gold you add to the solution.


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## rickbb (Jul 8, 2013)

It's my understanding that you EITHER reduce the AR with the 3x evaporation/addition of HCl, OR introduce urea to kill the nitric, not both. Also some use Sulfamic Acid instead of urea to kill the nitric.


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