Urea to pH

[goldnugget77]

Excess nitric must be neutralized with Urea to pH 1 +/- 0.4, then
drop gold with SMB.

What does this mean in simple language
pH 1 +/- 0.4

Thanks

 

[goldnugget77]

11. (NH2)2CO= Urea= 8 oz Urea, 480 mL Water. Used to neutralize excess nitric acid in
AR process before dropping gold with SMB. Add until solution doesn’t fizz and pH
reaches 1 +/- 0.4.

I think i found the answer

 

[Juan Manuel Arcos Frank]

I think it talks about a tolerance...from pH 0.6 to pH 1.4 ,I mean,0.4 less than 1 or 0.4 more than 1.
Regards.
Manuel

 

[goldsilverpro]

I've always read that you bring it to at least 1 and don't overadd. I don't know if 0.6 will work that well.

 

[Palladium]

Excess nitric must be neutralized with Urea to pH 1 +/- 0.4, then
drop gold with SMB.

What does this mean in simple language
pH 1 +/- 0.4

Thanks

I read it as a Ph of 1 with a tol of +/- 4 tenths of 1 unit.

 

[Gold Trail]

what is the best means of actually testing the PH? i have looked at PH meters but i assume they are not acid resistent? how well to the papers work? as were testing colored solutions wouldnt that effect the color of the ph test?

just wondering

ryan

 

[butcher]

my Ph meter has had no problems in the strong acids, but then again I never stuck it in hot concentrated aqua regia. :roll:

 

[EVO-AU]

What other chemical besides smb can be used for ppt in the a/r process ? Phill

 

[nicknitro]

EVo,

One comes to mind right off hand, Ferrous Sulphate (Copperas). It all depends on what your general strategy is. If you are just trying to recover PM's, almost any metal can be used. Copper,Silver,Zinc, Tin Not Recommended, Aluminum "Not recommended, unless in specific cases.", steel/iron, are all metals used to drop metals out of solution, albeit they are usually "recovery methods".

SMB is a more selective precipitating compound, in that it drops gold more efficiently than other base metals, ie. copper/zinc, common metals in gold solutions. Some copper or zinc will drop out with SMB too, depending upon the concentrations of the metals involved. The more base metals involved more will drop out and require you to further refine through subsequent processes.

Zinc is also used, as I have recently seen to be very functional in selectively precipitating PMG's from solutions as well. So bottom line, there is a solution for all your solutions, you just have to figure out where your refining is heading you too, and look into the specifics of the process you plan to use.

Good Luck,

Nick