silver plating wires

[arthur kierski]

i can get up to 500kilos monthly of silver plated wires which is used to plate custom jewllery----each kilo have 50grams of silver----how can i obtain this silver cheaply from the plated wires-??thanks in advance for yours sugestions---

 

[goldsilverpro]

Arthur,

Some ideas.

I assume you are talking about the wires used to hang the parts in the plating tank. I also assume the wires are copper. If this is right, much of the wire will not be in the solution and will, therefore, have no silver on it. Have you just seen samples or have you seen the entire batch? I would be leary of this unless I dumped the whole lot out and took a lot of samples, myself. If they have trimmed the bare copper wire away from the silver coated wire, it would be a different deal.

If the figures are right and, if the silver covers the wire uniformly, that is 5% silver or about 800 oz of silver/500 kilos of wire. That's a helluva lot of plating wire. It must be a huge plating shop with many employees.

Silver plated copper wire is generally not a very good refining item.I know of no economical way to strip the wire chemically. Even if you had a good stripper, the wire is probably mashed together and would be hard to strip. If you dissolve the copper alone or dissolve both the silver and copper, you will generate lots of waste. You might think of melting everything and use a standard copper sulfate/H2SO4 solution to dissolve and plate the copper out

If steel wire is used, full-strength nitric acid might dissolve the silver without dissolving the steel. It depends on the steel alloy. I have done this successfully on aircraft bearings. You must keep all water out of the solution or the steel will dissolve. Also, try to keep the solution cool. Another way of stripping silver from steel is with cyanide.

Give us more information.

 

[arthur kierski]

you assumed right---it is the wire used for plating the custom jewllery-------the wires are round(circle) and fully plated---some are steel(from one of the workshops),but mostly copper wires from other workshops------i asked for help because using nitric could do the work but it would be very expensive----i thought of using sodium nitrate(never used this chemical before)-----the store that sell to me acids ,cianides and all the othe chemicals gave me an idea that worked in an experiment that i did yesterday-----it is the following:for 16kilos batch----50liters of h2so4(full strenght) +5liters of hno3----you put the wire in this solution and every thing is dissolved----then you put this solution into 110liters of water carefully and then add more 55liters of water----at last you add nacl and all the silver precipitates as silver chloride----the yeald of silver should be 800grams(25ounces)---what do you think of this method?gsp-----50liters of h2so4(35dollars)+10dollars of nitric---brazillian prices---grossly 50dollars costs to make 350dollars of silver--i have all the equipment nescessary to do this work----do you think that this will work ? thanks for your replies and ideas(you are a very experienced man,a real master)--thanks GSP

 

[cmclean]

GSP:

In your post, you mention cyanide as another alternative to stripping the silver from the wire; what concentration should be used in order to just strip the silver and not affect the steel or base metals? In another post, Harold mentions that cyanide is selective for gold in low concentratios-something like 0.02% I believe; would this concentration also apply to the silver stripping process?
Thanks,

Carlos

 

[goldsilverpro]

50liters of h2so4(full strenght) +5liters of hno3----you put the wire in this solution and every thing is dissolved

This process has been covered many times on the forum. One of the latest is here.
http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=54&t=5105&p=44037&hilit=brass+world#p44037

If you are using full strength 96% sulfuric and 70% nitric, I seen no reason why any of the copper would dissolve. The process you outlined will work, of course, at least on copper. I haven't tried it on steel, but I think it might work. If you can handle the safety issues and the waste issues, it is viable, I guess. I never cared much for this system because of these issues. One of the biggest safety problems would be handling the finished wire - removing it from the tank and rinsing it without getting it on you. I would probably use long tongs and go very slow.

Were it me, I would play (using small quantities) with cutting the nitric back from 10% to 5%, by volume. When it slows down, I would then add more nitric, in increments - say, 1-2% additions. At some point, it will probably stop or will slow down to the point that you can't live with it, even with a fresh addition of nitric. You will also have to watch for attack on the copper. At that point, it would be time to harvest the silver. You may be able to dissolve a tremendous amount of silver if you keep water out of solution. Heat will help a lot, but large amounts of hot sulfuric are very dangerous to work with.

In your post, you mention cyanide as another alternative to stripping the silver from the wire; what concentration should be used in order to just strip the silver and not affect the steel or base metals? In another post, Harold mentions that cyanide is selective for gold in low concentratios-something like 0.02% I believe; would this concentration also apply to the silver stripping process?

The cyanide will not affect the steel in any concentration. The copper is another problem. Strong cyanide will attack copper as readily as it does silver, maybe even more so. I don't know the threshhold concentration to prevent copper attack but I would imagine it is very low - maybe only slightly above the .02%. The .02% strength mentioned by Harold was for ore. It is very slow. If I remember right, the ore is leached for several days. Also, whether weak or strong, cyanide alone will not dissolve Au, Ag, or Cu. It requires something to provide oxidation. With ore, the oxygen is provided by the air. With strong cyanide, there are a number of things that can be used - m-NBSS, H2O2, etc. For electrolytic cyanide solutions, it comes from the anode reaction. Note that all these things that provide oxidation, air, H2O2, anode reaction, etc., also progressively destroy the cyanide and weaken the solution.

 

[Platdigger]

What about ammonium thiosulfate for this?

 

[johnon]

Try Sodium thiosulfate, maybe add a little NH4OH to pH9-10. Can drop w/sodium sulfide (dry or in aq. soln)