As the saying goes --- "there is more then one way to skin a cat"
The sulfuric/nitric method is certainly another way to strip silver plating - this method has three benefits over the H2O cell
1) it is
MUCH faster at stripping the silver plating
2)
more complete stripping of the plating as the sulfuric/nitic (solution) gets into the nocks & crannies & dissolves the silver --- with the H2O cell the silver is not dissolved - rather it is knocked off by the DC current - the current is not as effective at knocking the silver off from inside the nocks & crannies - so some plating is likely to be left stuck in the nocks & crannies
3) the copper/brass is not effected by the sulfuric/nitric (which is why this method is used to restore plated items) the H2O cell has some effect on the copper/brass (very like but some)
The down side of this process is as we know sulfuric acid is one of the more dangerous acids to work with so
much more care needed when working with it - especially on large scale
Also you have the cost of chems to consider
Also recovery of the dissolved silver from the silver sulfate solution to consider
There are two methods for that
1) reduce silver sulfate to silver sulfide by cementing with iron & then reducing the silver sulfide to silver by smelting with iron/borax/soda ash --- this method does not allow you to reuse the sulfuric
2) reduce silver sulfate to silver chloride with HCl then reduce silver chloride with sugar/lye - or sulfuric/iron --- this method allows you to reuse the sulfuric
here are a couple of threads where this process has been discussed -----
https://goldrefiningforum.com/threads/new-youtube-content-coming.30348/#post-317891
https://goldrefiningforum.com/threa...kg-of-silver-plated-copper-servingware.30496/
Geo has done a couple videos with this method so if he sees this thread maybe he will chime in on this discussion &/or provide links to his videos
Kurt
When we look to this situation as to "I need to somehow do this 2000lbs", there are considerations you mentioned - and they are quite real. Firstly, decision need to be made about proper procedure. I do have some experience regarding ammonia based stripping methods, and as long they work, OK, but they are hell to perform on scale. That ammonia smell will rip your nose off, unless you will somehow work out how to create fume exhaust and hood large enough to fit regular small bathing tub into it.
After these experiences, and also being familiar with working with much more hazardous chemicals than just concentrated sulfuric acid, I will go with sulfuric/nitric on this one, even if it seems worse.
For this, source of tech grade concentrated sulfuric (95% is plenty sufficient) need to be found. You would need more than a several gallons of the stuff, and you need to find it cheap. There wouldn´t be that horrible consumption of nitric acid through the process, I will expect few gallons of 65% stuff will do. Aside of this, you will then need some good cheap source of tech grade sodium hydroxide (ordinarily sold as 25kg bags here) and several kilograms of tablesalt (for future conversion of Ag2SO4 to AgCl). There are possibilities of conversion of Ag2SO4 directly to Ag2O tho.
Nice thing about silver sulfate is that it can actually nicely crystallize out of the sulfuric acid solutions. Even nicer (in regard of efficiency) is to operate at elevated temperatures, and when the solution became saturated with Ag2SO4 and crystals will start to form, shut it down for that day, cover the beaker/vessel with plastic wrap to avoid moisture and let it cool overnight (solubility at 24°C - 31g/100g, at 96°C 127g/100g). To the morning, crystals will grow inside, and you simply pour the sulfuric acid off to another beaker, topple with a bit of fresh one and continue.
This would require diligence, thorough follow up on safety precautions, full PPE gear including apron and full face shield, long sleeved gloves etc. Heat will also help speed up the reaction - concentrated sulfuric acid will dissolve silver also on it´s own at elevated temperatures, so nitric use could be cut down even further. But it would be long chore, few pieces at a time, tied on a copper wire, submerged to the solution, wait a minute till leach do it´s job (nicely visually seen), remove, submerge in rinsing bath, second rinsing bath and finally wash with water.
But I can imagine it to be done fairly well. Like an afternoon after-work strange past-time for few weeks
wlearly, if you have that time and intial capital, courage, diligence and motivation, go for it.
Firstly, you need to get familiar with process in small scale - obtain the necessary PPE, sulfuric, nitric, hotplate... And give it a go with small sample to see if you will be capable to perform this right without severly injuring yourself.
Moreover, recovery rate with this process is indeed very nice
and byproduct is practically intact base metal, which you can sell as it is to the scrapyard - clean and shiny goes for top dollar. Or push it even further and try to find seller for that nickel alloys, as there is very considerable value in nickel
