question about suphamic denoxing

Advertise with us
Shop deals on ebay
xelexo
shop deals on amazon
Gold Refining Forum

Help Support Gold Refining Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
F

frank-20011

Well-known member
Joined
Jul 18, 2015
Messages
183
hello everyone,

i've bought sulphamic acid from an internet store over ebay and made a little test: put a few christals in HNO3 (first 37 and then 58perc.) put nothing happend.

i thought if much HNO3 in AR is still present after dissolving gold ( for ex. ) in it it fizzes and a lot NOx fumes come off so it should happens with HNO3 58 perc. much stomier but i can see nothing.

Regards, Frank!
 
Hello,

well, i will try it with a little warmer HNO3 again but i thought that the HNO3 straight from the bottle is much much more concentrater than that little HNO3 remaining in AR after the process so the reaction with sulphamic should much, much more stormier with it, even when it's cold.

regards, Frank!
 
You are comparing apples and oranges here.
AR which is HCl&HNO3 4:1 with metals in solution will react differently with sulfamic than straight nitric.
 
Warm the solution. The hotter the solution, the more vigorous the reaction will be.
Click to expand...

It is a straightforward reaction, HNO3 + H3NSO3 → H2SO4 + N2O + H2O. Why heat it to make it any more vigorous or react any faster? That slug of N2O is a colorless gas that you likely will not recognize until you get a whiff and realize why it is called laughing gas because of the "euphoric" effects of inhaling it. For a hobbyist refiner operating with no scrubber or a minimal thru-put scrubber, I would be wanting the reaction to proceed slowly to minimize that slug of laughing gas coming off.
 
When I use sulfamic acid, it is to remove residual amounts. It helps to heat the solution. A hobbyist shouldn't be working with amounts that would cause that much off gassing anyway. If they are, they are wasting acids and should reconsider the process. Personally, I drop gold and leave it overnight. By the time I get up and test it, if there was excess nitric acid, I just add a little more SMB. There is the occasion I want to drop and clean gold powder in one day. By heating the solution, I can remove the excess nitric acid much faster. If there is a safety issue such as exposure or boil over, precautions should be taken before the process is started. If you don't have proper fume control, do all reactions outside with a good breeze. Work with the wind to one side, either side and never with the wind to your back or face. I understand that those of us that have done this for awhile take these things for granted and sometimes it needs to included in the discussion. I apologize for not including it earlier.
 
hello,

you see not the gas but i THOUGHT you con see it bubbles?!


" if there was excess nitric acid, I just add a little more SMB"

i think i have to denox before adding SMB, maybe by sulphamic, maybe with more gold, maybe be heating (no option for my).

to say it again i only thought so: clean and concentrated HNO3 should react clearly visible with any sulphamic which is added.

regards, frank!
 
hello,


yesterday i've warmed up a few ml's of 58 perc. ( in a test tube, ~70°C) HNO3 and put a much crystals of sulphamic in it until nothing more dissolves and the same as befopre: no visible reaction...after that i let it boil but it was HNO3 again no H2SO4, with a little Cu it reacts fast to the nitrate.

is the conclusion of that my sulphamic isn't sulphamic?

i've bought it here in germany it's called "Amidosulfonsäure" so everything SHOULD be o.k.?!

regards, frank!
 
frank-20011 said:
hello,


yesterday i've warmed up a few ml's of 58 perc. ( in a test tube, ~70°C) HNO3 and put a much crystals of sulphamic in it until nothing more dissolves and the same as befopre: no visible reaction...after that i let it boil but it was HNO3 again no H2SO4, with a little Cu it reacts fast to the nitrate.

is the conclusion of that my sulphamic isn't sulphamic?

i've bought it here in germany it's called "Amidosulfonsäure" so everything SHOULD be o.k.?!

regards, frank!
Click to expand...
You may not be seeing a difference in reaction speed.
If the H2O has nothing dissolver in it but NO3 to create HNO3 there will be room for N2O to stay in solution.
When other chemical's are dissolved this leaves less solubility for the gas and you see a faster evolution of bubbles.
The same principle can be observed with Metal Alloys as well as solution's.
 
hello,

and thank you for your answer!

"When other chemical's are dissolved this leaves less solubility for the gas and you see a faster evolution of bubbles."

mhmm, o.k. about the gas evolving but if there are so much sulphamic acid crystals present that a lot of these crystals do not dissolve in the HNO3 the whole HNO3 should react to H2SO4 (i've boiled it, more than one time!) and no nitric should stay in these sollution but no, the test stated that clearly concentrated HNO3 remains there!
this is no denoxing and so i must doubts again on the purity of the sulphamic and even on its identity or to say it clearly: is it sulphamic? or what is it?

tahnks and regards, frank!
 
frank-20011 said:
hello,

and thank you for your answer!

"When other chemical's are dissolved this leaves less solubility for the gas and you see a faster evolution of bubbles."

mhmm, o.k. about the gas evolving but if there are so much sulphamic acid crystals present that a lot of these crystals do not dissolve in the HNO3 the whole HNO3 should react to H2SO4 (i've boiled it, more than one time!) and no nitric should stay in these sollution but no, the test stated that clearly concentrated HNO3 remains there!
this is no denoxing and so i must doubts again on the purity of the sulphamic and even on its identity or to say it clearly: is it sulphamic? or what is it?

tahnks and regards, frank!
Click to expand...
Try a melting point test.it should melt and denature at about 205c.
Or go shopping with reputable suppliers.
Life is hard enough with out knowing what you are trying to use.
But using sulfamic is a short cut I do not like to use on it's own.
I find it very handy to use instead of the second or third evaporation or when the liquor has a predominantly Nitric composition.
most of the processes excel when they are run at a sedate pace or even left a day between step's . give it time to react and it eventual will do so.
 
hello again,

strange, strange, strange:

today i've dissolved a top of a spatucla of concentrate from ashed IC's and a little gold-braze in 2ml HCl/0,5ml HNO3 and a little bit water, after the reaction stops i add a few crystals of sulfamic and: gas bubbels evolved, after bubbling stops i decanted the clear yellow liquid in a clean test tube an add potassiumMB in Water, again gas evolved and the lovely smell of SO2 comes with it...after a few minutes gold settels an the test tubes bottom. (my first time :shock: )

after these pleasant observations which diffuse my concernings about my sulfamic i take again my bottle of HNO3 and suck again a few ml's of HNO3 out of it, squeese it in an test tube, add a little bit water (no gold and no HCl) and, at least a few crystals of sulfamic again and...AND: no evolving of any gas.

best regards, Frank!
 
Here is a short video I've made that may help you visualize how the sulfamic acid works. I speak a form of English, southeastern united states that you may not be able to understand but the video is in real time start to finish. That solution is from dissolving black fiber processors with the chips removed.

https://youtu.be/vznQ2O384C0
 
I said it before, I love that southeastern pronunciation... it is slow and measured, much easier to follow than someone fast speaking from Oxford or England at all.
 
hello,

thaks geo, i understand your pronunciation very good. (understanding is much easyer as to express something what i mean!)

your video was one matter why i couldn't understand that my sulfamic does not bubbels/react if i put it in clean HNO3 straight from the bottle but with reacted AR it reacts like yours in the video.
i don't know why but so it is!

thanks and best regards, Frank!
 
Because the mechanism by which sulfamic acid is oxidized is completely different in aqua regia or nitrosulfuric acid vs. plain nitric acid.
Not saying that you can't make N2O from sulfamic with nitric, just that it needs a halide as a catalyst. In practice, bromine or bromide is effective.
 

Latest posts

Back
Top