Went to see a client who processes a lot of silver. He had gotten in some dirty silver, about 60% silver and some iron copper and cadmium. So he didn't melt it, he just dissolved the contacts in 50% nitric to cement the silver for his cell. A process he has done repeatedly with lower grade silver.
This time he told me that no matter how much copper he added for cementing, the silver wasn't dropping. And his copper bars he was using for cementing were turning into some spectacular looking crystals. These are the bars he uses for cementing in a basket for me to see.
Pretty bars huh?
During the week he tried cleaning the bars off and they looked like this;
So you can see it looked like copper bars to start with.
I asked him to fill a small beaker with a sample of the solution and give me a short length of Romex from the maintenance room. I took the 250 ml sample and removed the ground wire from the Romex and made a coil shape and put it in the sample. Bang, silver dropped like nobody's business.
Now I asked about his copper, because it worked like a charm with copper I knew was pure. He had spools of Angel Hair fine copper wire he had bought at auction which they melted into bars. And they looked like fine looking copper bars. After ferreting around in the container where the spools of this wire were stored I found one spool with a label.
What looked like spools of nice copper wire was spools of nice copper clad wire or should I say aluminum with copper cladding.
Well that explained it. I knew something was awry when I saw the copper was coming out of solution but the aluminum was really not apparent in the melted bar form, or as wire either. But the copper nitrate crystals were forming freely and the silver stayed in solution.
When they called me earlier in the week I told them what is often advised here on the forum. Just save everything, solution and solids until I see it.
So the moral of the story is what looks like copper, ain't always so!
This time he told me that no matter how much copper he added for cementing, the silver wasn't dropping. And his copper bars he was using for cementing were turning into some spectacular looking crystals. These are the bars he uses for cementing in a basket for me to see.
Pretty bars huh?
During the week he tried cleaning the bars off and they looked like this;
So you can see it looked like copper bars to start with.
I asked him to fill a small beaker with a sample of the solution and give me a short length of Romex from the maintenance room. I took the 250 ml sample and removed the ground wire from the Romex and made a coil shape and put it in the sample. Bang, silver dropped like nobody's business.
Now I asked about his copper, because it worked like a charm with copper I knew was pure. He had spools of Angel Hair fine copper wire he had bought at auction which they melted into bars. And they looked like fine looking copper bars. After ferreting around in the container where the spools of this wire were stored I found one spool with a label.
What looked like spools of nice copper wire was spools of nice copper clad wire or should I say aluminum with copper cladding.
Well that explained it. I knew something was awry when I saw the copper was coming out of solution but the aluminum was really not apparent in the melted bar form, or as wire either. But the copper nitrate crystals were forming freely and the silver stayed in solution.
When they called me earlier in the week I told them what is often advised here on the forum. Just save everything, solution and solids until I see it.
So the moral of the story is what looks like copper, ain't always so!
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