# Cemented Copper to Cement Silver?



## MysticColby (Jan 13, 2012)

I've read a couple times on here where people use iron to cement copper that was recently used to cement silver
silver nitrate + copper -> silver + copper nitrate
copper nitrate + iron -> *copper* + iron nitrate

now, can this copper be used to cement future silver?
I know that it will also cement nickel, tin, lead, etc. (not a huge problem).
but my biggest concern is what the iron is alloyed with. Even cast iron has up to 4% carbon and 3% silicon.
Won't this carbon contaminate the copper, then the silver? or would it burn away / bind to flux when you melt the silver?
And I don't see silicon on the reactivity series, wouldn't that contaminate the future silver as well?

There are alloys without carbon and silicon that only have other metals on the reactivity series - what are these used it?


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## freechemist (Jan 19, 2012)

Hello MysticColby,

Yes, this copper can be reused, to cement further silver. When melting silver under flux, silicon and carbon can be oxidized by careful addition of small quantities of an oxidant to the molten mixture. Carbon is volatilized as CO2 and/or CO, depending on the melt-temperature, and silicon, being oxidized to SiO2 enters the flux, which most probably already contains some silica. As oxidants you can use potassium-nitrate or sodium-peroxide. 

Regards, freechemist


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## MysticColby (Jan 20, 2012)

for flux, I've always used just borax.
might they oxidize even without an oxidizer? (from the air)
I'll be running it through a silver cell, so this might not be an important issue.


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## Geo (Jan 20, 2012)

it depends on your feed stock. if your silver nitrate is free of contaminants, and the copper is pure and clean starting out then you will have clean copper nitrate.if you use a clean piece of steel to cement your copper then you should only have trace amounts of impurities. be sure to watch the cementation process closely and take the steel out before all copper has been cemented as this will not give the iron time to break down and contaminate the copper.


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