First Time Refining Sterling Questions?

[rybak97]

I recently purchased 475 grams of sterling ingots from a local guy who goes around to all the estate sales and buys this stuff up like crazy. I paid 86% of spot for the lot which at the time came out to about $355. I scratch tested all the ingots (11 of them) and they all tested as sterling with a nice dark red color, using JSP solution (Nitric Acid and Potassium Dichromate).

I've recently acquired all the parts and pieces ill need to refine this as well as a few other lots of sterling I’ve acquired including an electric crucible, power supply for the Thum cell, Nitric acid and the other various parts and pieces needed for the process.

I’ve been reading up for about a month and after finally getting everything together I decided to give it a go.

Here is my set-up for the first 475 grams of sterling (Up to Cementation):676ml of nitric and 676ml of distilled water. I’m using a large glass beaker for reaction vessel in boiling water bath outside for additional heat (Propane Burner, same one I use for brewing beer). I’ve got an 8in watch glass on top of beaker for the entire time. Copper cementation after adding an additional equal volume of distilled water to the resulting silver nitrate.

Step by Step:Place sterling ingots into beaker. Add 676ml of boiling distilled water to ingots. Gradually add Nitric in small increments up to calculated amount. Keep hot water bath between 180-200. Remove from heat once reaction complete, filter into holding vessel for cementation. Add an equal amount of distilled water to vessel before cementation.

I’ve completed all the steps above and have filtered my silver nitrate through one layer of muslin and one coffee filter. The solution was very cloudy and had a purple tint to it?? I’ve got another batch of sterling going right now which I plan to add to this in the cementation vessel before I start that process. From what Ive seen on this forum the silver nitrate solution should be very clear and strikingly blue. Am I doing something wrong? Did I get a bad lot of sterling; maybe they added some other metal to it?

Any advice would be much appreciated; I don’t want to move forward before I get this purple tint and cloudiness figured out. Thanks all.

See pictures......

 

[rybak97]

Everytime I try to add a picture it asks me to type "Noxx". I do that and the picture never gets added???

 

[jimdoc]

Everytime I try to add a picture it asks me to type "Noxx". I do that and the picture never gets added???

Could the picture be oversized? That used to block certain photos, but I think the newer software takes care of it. Try resizing the photos to see if that helps.

Jim

 

[rybak97]

Everytime I try to add a picture it asks me to type "Noxx". I do that and the picture never gets added???

Could the picture be oversized? That used to block certain photos, but I think the newer software takes care of it. Try resizing the photos to see if that helps.

Jim

Will do, stand by. thanks.

 

[rybak97]

Nope, didnt work. I think its because Im so new to the forum. Ive emailed NOXX to see if they will let me post some photos.

 

[rybak97]

I’ve completed all the steps above and have filtered my silver nitrate through one layer of muslin and one coffee filter. The solution was very cloudy and had a purple tint to it??

I just read on one of the old posts that silver nitrate can turn purple in the presence of sunlight. I was doing the dissolving outside, in S Florida, at Noon, and needless to say there was plenty of sun. Could this be where the purple tint came from?

 

[butcher]

Silver chloride can turn purple to gray in sunlight, it is light sensitive, the sunlight can convert it to silver, this reaction is used in photography, silver nitrate is also slightly photo sensitive, but not enough to be used in photography, bright sunlight can decompose silver nitrate to elemental silver, this is one reason silver nitrate solution is stored in amber bottles, I do not know if the purple a silver compound or not, but I just have to wonder if there was a possibility of chlorides being involved which could have formed some silver chloride.

 

[nickvc]

I suspect that you have colloidal gold in your solution, I get a similar colour when working with slimes from the cell. As you intend to refine the cemented silver I wouldn't worry as the anode bags will capture the gold and any PGMs if you operate it correctly for later refining, you may have a bonus from this silver.

 

[rybak97]

Thanks for the Reponses. I was a little leery about the purple color but once I dropped my copper and the silver started falling off I felt much better. Since then Ive cemented all the silver from this first run, testing the remaining solution for silver (there was none) and stored the remaining fluid so I can cement some copper once i find a piece of iron. Its amazing how hard it is to find Iron! Can I just use low grade steel??

Anyway, Im in the process of cleaning the cement then Im going to throw it all in the new Hardin melting furnace to make some ingots for the thum cell. Wish me luck!! Hopefully Ill be able to post some pictures next time.

 

[butcher]

If you deal with computer scrap you should have what you need.

The steel from computer cases will work to cement copper, or you can use other types of steel, or rebar will work to cement copper.

A source for fairly pure soft iron I use transformer laminates cut or ground off welds with a grinder, then you can pull apart the iron laminates, they have shellac coating, actually the coating is helpful keeping the iron from rusting before you wish to use it, the shellac can be burnt off with a torch, and rinsed in water before you use.

The iron transformer laminates I use to make ferrous sulfate (copperas) used to precipitate gold, by dissolving the iron in 10% H2SO4 with heat, filter solution, crystallize, re-dissolve in dilute sulfuric acid re-crystallize for very pure light green FeSO4, store damp in a little acid solution, HDPE container with good lid to keep air from oxidizing the ferrous sulfate (oxidized the brown iron sulfate will not precipitate gold), you want the green crystals for precipitating gold.