QuestionHi.
I would like to ask how to refine a silver with HNO3 and Copper. My question is the quality n quantity of Nitric acid per gram of 800-925% silver.
I did some research that most of people are using 30-35% HNO3 150mL for every 30gr of silver. Do I have to add a water as well???
Another question is how to clean/brightning the silver from the dark spot (sulfur). So far i used backing soda n alluminium. Do you have any rough estimation...between the water n baking soda? How about other chemical product?
I cant really buy silver dip coz it would be expensive (200% tax duty to my country)
For polishing, I use the OTEC sand polishing (centrifugal). How about the vibrating technique.. is it better?
nb: I have to brightening 50-100gr of silver jewelery everyday, so strong home made chemical product will be usefull
thanks
alex
AnswerHello Alexander,
First and foremost - DO NOT USE ALUMINUM in any process involving silver excepting the cleaning kits as sold on the tele. It will blacken fine silver and other fine silver based products ( metal clays for instance).A far better way to go is to simply pickle it. If you are using nitric acid a typical bright dip should do it.
As for the heart of the question:
I am not sure what you are trying to accomplish..it sounds like you are trying to reclaim silver from x, the hard way.. the easiest way to refine silver is to make sure all solder is removed then melt, adding a pinch of sal ammoniac ( available at a stained glass supply house), the the crucible and - using a graphite rod, when the molten metal begins to roll into a red hot ball, use the rod to remove imperfections.. then pickle in sodium bisulphite, or a nitric acid pickle ( always add acid to water). The use of copper to refine silver is very outdated. Cuprous Oxide, Cu2O reacts with concentrated Nitric Acid, HNO3, or with dilute Nitric Acid, HNO3, on heating, when the Cuprous Oxide, Cu2O dissolves with evolution of Nitric Oxide, NO.
3Cu2O + 14HNO3 ==> 6Cu(NO3)2 + 2NO + 7H2O If the solution is heated the nitrous acid decomposes to give nitric acid and nitric oxide.
3 HNO2 ==> HNO3 + 2 NO + H2O. Nitrous oxide being of no use at all in your process. If you are trying to separate a plating from silver then the best way to accomplish that is with a technical procedure that is too long to explain in this forum!.So if you could enlighten me as to what you are actually trying to accomplish I could be more definitive.
best regards, Ari
Ok-HNO3 with add water unless you buy a concentrate or obtain a concentrated form of it in which case the instructions should be on the package.
