# Contacts 1 x 3/4



## metatp (Nov 28, 2009)

Hi. I've run into a similar issue that I had before that is still a mystery. I have these contact that test positive for silver, but once I put them in nitric acid, things don't go as planned. The contacts are 1 inch by 3/4 inch by 1/8 inch tapering down to 1/16 inch at the sides. See picture. I was told that they came from motor starters.


The contact starts to dissolve, but crumbles into this reddish powder that turns tans/peach color if i let it sit in Nitric acid. I filtered and washed the residue in distilled water then let dry. This is what I got. I put some of the tan powder in a little bid of about 15% HCL. A reddish orange solution was formed. I tested the reddish solution with stannous and got a very very dark blue.

Does anyone have any idea what this material is, or what is forming when add to nitric acid?

Even thought the solution in nitric was clear with a slight blue tint, when I place cooper to cement the small amount of silver, the solution turned a very dark blue, almost black. I do not have and DMG, so I can't test for palladium with DMG.

Thanks,
TomView attachment 2
View attachment 1


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## Harold_V (Nov 28, 2009)

I'm not sure I can tell you what the material is, but the contact can be processed for full recovery of the silver contained within by heating the dilute nitric. It's a slow process, but it does happen. 

The silver that cements from the solution tends to drag with it some of the dissolved material. I found that a wash with HCl yielded a dark blue solution, just as you described, so that was my procedure. By pursuing the wash, it appeared to me that the bulk of the contaminant was removed. Silver from such a source appears to be of high quality once melted, but the addition of a small amount of borax insures that any remaining traces are absorbed in melting. I am not convinced the material is of value, although I am not certain that it is not. 

Pouring to a cone mold is a good idea when using flux. The surface area of the button is reduced considerably, making removal of the flux quite easy, and assures that the silver is extracted from the flux. The only exception would be if the flux cover is quite viscous and does not permit easy flow. In that case, the addition of more borax or even some fluorspar to thin the slag is a good idea. 

Harold


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## metatp (Nov 28, 2009)

Harold,

Thanks again. If the other material has no value, they really aren't worth processing unless I has a lot of them. There's not that much silver. I forgot to mention that each weigh about 13.5g. I think it puts the density around 13 or 14 g/cc.



Harold_V said:


> Pouring to a cone mold is a good idea when using flux.Harold


Do you know where I can get a cone mold? I have a couple pounds of silver powder that I want to start melting, and i would love to try a cone shape mold.

Thanks,
Tom


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## 4metals (Nov 28, 2009)

Legend sells cone molds these are for larger pours

Cone Molds

they also sell small ones in the assay section, usually 4 or 6 depressions on a mold


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## Anonymous (Nov 28, 2009)

Checker pattern and high density usually tungsten with silver mixed in.
You can sort these pretty quick, if you try and cut them with side cuts they are 
harder than heck and I personally have never been able to do it.

Jim


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## metatp (Nov 28, 2009)

james122964 said:


> Checker pattern and high density usually tungsten with silver mixed in.
> You can sort these pretty quick, if you try and cut them with side cuts they are
> harder than heck and I personally have never been able to do it.


They are easy to break once you take out the silver. They just crumble.


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## Harold_V (Nov 28, 2009)

HTPatch said:


> Harold,
> 
> Thanks again. If the other material has no value, they really aren't worth processing unless I has a lot of them. There's not that much silver. I forgot to mention that each weigh about 13.5g. I think it puts the density around 13 or 14 g/cc.


While I don't know that I'm right, I have long believed the balance of the material was likely tungsten, perhaps combined with the silver in a somewhat different manner. The contacts you mention lack the waffle pattern of the typical tungsten/silver contact. If I am wrong, please correct me. 

Assuming they are the ones I recall, yes, they are worth processing. Tungsten contacts yield less than 50% silver, but it is easily extracted, just slow. They do not require tending. You can cover the contacts with dilute nitric then allow it to work for a few hours. A low boil, with a watch glass covering the vessel to prevent loss of vapors and you're good to go. 



Harold_V said:


> Pouring to a cone mold is a good idea when using flux.Harold





> Do you know where I can get a cone mold? I have a couple pounds of silver powder that I want to start melting, and i would love to try a cone shape mold.


I see that 4metals has provided a source. I made a pattern and had mine cast. I still have the pattern, and could possibly pour some at some point in the future, but that can't happen in the immediate future. My induction furnace is not operational, and won't be until I no longer live in the shop. I would consider offering cone molds and ingot molds for sale at some time in the future, assuming there was a demand. 

Assuming you get a cone mold, be certain to dress it with some kind of coating. The small ones tend to be heavy enough to prevent any soldering of the values to the mold, but large volume pours tend to not freeze quickly, so the pouring action of the molten metal will often scrub the surface well enough to permit fusing of the molten values. An oxidized surface that has been coated is cheap insurance that should prevent any problems. 

Once you have soldered your values to a mold, it must be heavily worked to free it from all traces, otherwise each pour will solder to the mold. 

I highly recommend a new mold be heated until it oxidizes, then coated with lamp black. Replenish the lamp black as needed. It's cheap insurance. 

Be careful when heating molds. If they are cast iron, they are subject to thermal shock and cracking. They should be heated slowly and uniformly. Never by torch, unless you have a huge flame. A propane weed burner, for example, would work, but a single tip oxy/acet torch is asking for problems. If your choice is an oxy/acet rose bud, move the torch constantly to insure uniform heating. 

If you have a choice, specify ductile iron for molds, not gray iron. Ductile iron has greater tensile strength and is far more forgiving of being heated. It offers the same benefits of gray iron without being as fragile. 

Harold


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## metatp (Nov 28, 2009)

Harold_V said:


> While I don't know that I'm right, I have long believed the balance of the material was likely tungsten, perhaps combined with the silver in a somewhat different manner. The contacts you mention lack the waffle pattern of the typical tungsten/silver contact. If I am wrong, please correct me.


Harold, 
There is a smaller than normal waffle pattern, but there is a little solder hiding it. These contact differ from the normal tungsten contacts I have been processing. They routine ones stay mostly intact even after the silver is fully dissolved in nitric. These contacts took even longer, and they turned red/brown and started to disintegrate and made it difficult to filter. The left over that hasn't started disintegrating yet I can not break. There is still half the sample left and 20% silver was recovered. Don't know if there is any silver left.

Thanks for the other information.

Tom


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## Harold_V (Nov 30, 2009)

Aside from not remembering the color you mentioned, you are experiencing exactly what I expected. I realized from the outset that there were numerous variations in silver contacts. I never encountered one that wasn't worth processing, and definitely remember those that left no solids the way the typical waffle backed tungsten contacts did. Just as you described, they broke down to a material that somewhat resembled silver chloride, aside from the color, and left nothing behind the way tungsten contacts do. These contacts were the very source of the cemented silver I'd wash with HCl after recovery of the silver with copper. It, routinely, yielded a dark blue (think of blue ink) color with the wash. Indications are that anything that may have gotten past the HCl wash was picked up by the borax flux used in melting the cement silver. I never had anything in my silver cell slimes that was troublesome when recovering the values. 

Filtration. 

Why bother? What's the hurry? If you're troubled by the flocullence, there's nothing preventing you from allowing it to settle. Decant, then rinse. If you find you must filter, filter only the remaining traces. That's much faster and easier. 

I NEVER filtered silver nitrate solutions. Why would you? You gain nothing that won't come from melting with a flux, unless you eliminate traces of lead nitrate in the process. In my case, lead was rarely a consideration, so if you process lead bearing materials, you may wish to rethink my comment. 

I used tap water when dealing with inquarted materials. I flat didn't care if traces of silver were converted to silver chloride. The way I dealt with my materials, it would be gathered and eventually recovered. That was better, by far, than to spend money unnecessarily, with no real gain, to say nothing of the time involved in playing with the solutions. In the same vein, I used tap water for processing contacts. Same reasoning. I would do the same thing today were I refining. There simply isn't enough advantage to using purified water to make the difference. YMMV, so you may not share my opinion. 

Do remember, I refined for gain. Time, to me, was money, and I was always behind, thanks to a very successful operation. You, as a hobbyist, may see things differently. There is no right or wrong way, just ways that we find comfortable, or best serve our circumstances and expectations. 

Harold


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## metatp (Nov 30, 2009)

Harold_V said:


> they broke down to a material that somewhat resembled silver chloride, aside from the color, and left nothing behind the way tungsten contacts do. These contacts were the very source of the cemented silver I'd wash with HCl after recovery of the silver with copper. It, routinely, yielded a dark blue (think of blue ink) color with the wash.


This is exactly what I am seeing. 



Harold_V said:


> Decant, then rinse. If you find you must filter, filter only the remaining traces. That's much faster and easier.


That seems simple. Maybe that's why I didn't think of it. I have plenty of time. This should not be a problem. Thanks. Sometimes the obvious is the last thing one thinks of.



Harold_V said:


> I NEVER filtered silver nitrate solutions. Why would you? You gain nothing that won't come from melting with a flux, unless you eliminate traces of lead nitrate in the process. In my case, lead was rarely a consideration, so if you process lead bearing materials, you may wish to rethink my comment.


Don't deal with much lead here. 



Harold_V said:


> There simply isn't enough advantage to using purified water to make the difference. YMMV, so you may not share my opinion.


I have a large supply of purified water. I think I will continue to use it with the silver nitrate. I just don't trust our water supply here in FL.

The residue did settle very quickly for these contacts. Maybe they are worth it if I get enough of them. Besides, I like the pretty color changes.  

Thanks again Harold. You are a wealth of information and thanks for sharing.

Tom


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## Harold_V (Nov 30, 2009)

HTPatch said:


> I have a large supply of purified water. I think I will continue to use it with the silver nitrate. I just don't trust our water supply here in FL.


Great! Don't get me wrong. I don't recommend against purified water, just suggesting that if it's the slightest inconvenience, you can get by perfectly well without it as long as you're not trying to make electrolyte or test/standard solutions. 

I have a water still, which I kept from my years of refining. It's a small unit, hardly fit for large production, but it was adequate to keep me well supplied with distilled water for my needs. 

I ran it last weekend, to have distilled water on hand for various reasons. It runs to waste, water at a ratio of about 5:1 for each gallon of distilled water it produces. It also consumes a respectable amount of electricity, although our rates, here, are very low (4.333¢ kwh). Still, when I was refining, I couldn't see an advantage to distilled water for many of the operations, in spite of having it at my disposal at all times. You need not share that position, nor do I think those that don't are fools. We all do what makes us comfortable. I wasn't the least bit unhappy with using tap water, and found my quality above reproach. I may have felt differently had my objective been ultra pure metals (5n's or better), but that was never my intention. I wanted to put out a product that was at least as good as that which was available from major refineries. I did that, with a margin to spare. As a result, I was happy with my processing. Each of us must dance to the music we hear. 



> The residue did settle very quickly for these contacts. Maybe they are worth it if I get enough of them.


That was my experience, as well. I'd pour off the solution to a settling container, then siphon that which was clear of flocculence. In the end, I'd filter the residue, which were then incinerated and placed with all my other wastes. Any values that may have been left behind were recovered when I ran my material, prior to retiring. It was a wonderful savings plan, one that couldn't be tapped for other needs. 



> Thanks again Harold. You are a wealth of information and thanks for sharing.


My pleasure, for sure. I try to dispel stupid notions and provide tips that make refining easier. Many of them I had to learn the hard way, not having anyone to consult. It's amazing what common sense can do for you when you are left to your own devices. 

Readers of this forum are very fortunate to have a few of us that willingly share knowledge that was hard earned. Those with enough wisdom to capitalize on the opportunity can spend their time productively, instead of trying to re-engineer the wheel. 

People like you make it worth while. I thank you for your trust in my guidance.

Harold


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## metatp (Nov 30, 2009)

Harold_V said:


> I thank you for your trust in my guidance.


It is easy to trust your guidence when I see that others have done so with success, and I can confirm your approach with my own testing. The biggest benefits you ever provided for me are
1) The process of incineration
2) Not throwing away anything until we know the value is removed
3) Testing for value instead of chasing rabbits blindly
4) Reading Hokes

The rest is just picking your brain for specifcs concerning the recovery of silver. I had the same questions about 25 years ago, but the information did not seem to be readily available for me. Never knew about Hokes.

Tom


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