Nitric. Super Slow flow. PLEASE HELP!

[Big_AL_305]

So im new to this refining stuff. i normally do bench sweeps and have absolutely no issues. as a matter of fact ive sold my gold to the local refinery and had it come back 99.996.

So now. ive attempted to do my polishing dust. what a nightmare!
normally i burn, then crush, then nitric acid to get the silver out. then AR.
but im having a super difficult time filtering the nitric acid this time around.
its just not flowing thru the filter.
using whatman #1 and #4

Is there excess nitric? causing it to not flow?
or ?
PLEASE HELP

 

[nickvc]

Did you use heat while dissolving the values ?
It’s also possible an addition of Hcl might help if it’s mixed well throughout the powders.

 

[Big_AL_305]

i did use heat. and i dont use powders.
i use liquid nitric acid
and i use liquid hydrocloric acid

please give me some advice

and a question. if i add Hcl would that cause AR to start

 

[nickvc]

By powders I meant the incinerated polishings.
Did you actually boil the sweeps? I ask because it’s one of the few times I would advise this but use a watchglass and stir regularly to avoid hot spots and beakers cracking. The idea behind adding more Hcl is to thin down your acids as with sweeps they can form quite sticky solutions that can take a long time to filter even using a pump.
You could try using a coarse filter first to remove as much pregnant solution as possible and then rinse well with water and then fine filter that solution to remove any contaminants.
Sweeps generally are a pain to process and you use much more solution than for most other types of scrap but polishings can yield upwards of 25-35 grams a kilo depending on what you polish.
You mention using nitric first and that could be your problem, if you didn’t remove all the nitric solution as soon as you added Hcl you formed silver chloride and that with fine powder from the sweep can block your filter very nicely.
Unless you expect a large quantity of silver from your sweeps I’d advise boiling in Hcl first which will remove a lot of base metals and some troublesome elements that can make filtering a pain.
Another point is whether you properly incinerated the sweeps as the polishing rouge contains oil based products I believe which can also be the problem.

 

[nickvc]

One more point for you to remember is even if you process the sweeps correctly you will only recover 90% on the first treatment, a second processing is always a good idea if you expect significant values or you feel the yield is low.

 

[Big_AL_305]

Ok, so to confirm exactly where I'm at here, I have my Nitric solution that needs to be filtered, but the solution is too thick. What steps can I take right now to get this to filter? Am I adding Hcl and then filtering? Your response is greatly appreciated, Im just having a hard time understanding instruction here. Thank you in advance!

 

[Big_AL_305]

Ok, so to confirm exactly where I'm at here, I have my Nitric solution that needs to be filtered, but the solution is too thick. What steps can I take right now to get this to filter? Am I adding Hcl and then filtering? Your response is greatly appreciated, Im just having a hard time understanding instruction here. Thank you in advance!

 

[nickvc]

Try adding some distilled water to thin your nitric down and then try to filter.
Sorry I’d assumed you had already used AR after using nitric but reading your OP I see your stuck at the nitric stage.
If you don’t polish a lot of silver in future do not bother using nitric but go straight for Hcl and then AR which will make filtering much easier, at present you are chasing cents while your dollars sit there waiting for it all to filter.