# Non-magnetic stainless steel in jeweller's sweep ash.



## Quirkzunc (Oct 24, 2007)

Can anyone give me an answer to this problem?

I have been recovering precious metals from all sorts of jeweler's sweep ashes for a number of years by melting the ash with flux and pouring the molten mixture into conical shaped moulds. This always works very well for me, however sometimes there is stainless steel in the ash that is of a grade that is un-attracted to a magnet. When it is present as larger pieces that can be visually identified, such as watch band pins or steel shot it can easily be removed by sieving the ash and picking the pieces out with tweezers. This is not possible in all cases however because the pieces of stainless steel are in the form of filings or tiny spindles that do not trap by magnet or sieve. This stainless steel, when left in the ashes during melting will collect as a mush that floats in the precious metal pool at the bottom of the crucible and interferes with the metal's ability to flow from the crucible and into the mould. Anyone familiar with this process would know that when melting these kinds of ashes the crucible will contain maybe 90%+ molten flux/ash mixture with the metal present only as a small puddle underneath all of that. Any mush that remains un-melted in the bottom of the crucible will trap some of the valuable metal amongst it and not allow it to flow from the crucible properly. Although this interferes with the return it is only part of the problem of having this material present. The difficulty then lies in obtaining a homogeneous sample of the collected precious metal for the purpose of an assay while it has all of this steel much in it.
If anyone has a solution to this problem that they can share with me I would be most grateful.


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## Irons (Oct 24, 2007)

like those found in hard drives?

If there's any magnetic attraction at all, that will pick it out.


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## Quirkzunc (Oct 24, 2007)

Yes.

The problem with using too stong a magnet on jeweler's sweep ash is that often there is iron oxide present as a very fine powder in the ash. This is the abrasive substance used in 'Rouge' which is a polishing compound commonly used by jewellers.
This iron oxide picks up quite easily with a rare earth magnet but it is not necessary to remove it because it poses no problem to the melt. If you do attempt to remove it, quite often you will remove qite a lot of the precious metal bearing ash along with it. If you use a ceramic magnet you and you dont get too close to the ash you will only pick up the problem little pieces of iron and leave behind the harmless iron oxide.
Having said all of that, there are some grades of stainless steel that have no attraction even to a rare earth magnet and these are the ones that I have problems with.

Thanks for the reply
QZ


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## Never_Evil (Oct 25, 2007)

My initial thought would be to mix the sweeps into a nitric bath and redrop the precious metals while the acid holds the other metals. I hope harold or steve can give a little more insite or a better way to do it.


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## Harold_V (Oct 25, 2007)

To be quite honest, I'm at a loss to explain the source of much stainless in jeweler's waste. The closest I came was with stainless burnishing bits, and they're mildly magnetic. 

There is no need to melt jeweler's wastes (filings). Larger pieces need to be inquarted, but filings will process adequately simply by incinerating, screening (to sort the larger pieces from the filings), then a hard boil in nitric and water, then after a proper rinse, on to AR. 

One of the tricks that can be used when you have base metals included with precious metals is to dissolve the values with AR, then allow the values to precipitate on the base metals. That will happen simply by introducing AR to the container, and heating until action ceases. At first the values go into solution, then they are precipitated, dissolving the base metals in the process. You can do this until the base metal is all but gone, at which time you can dissolve everything for a final time. If you elect to try this process, the solution, after values have precipitated, should be discarded when they test barren of values. That way you eliminate the contaminants, leaving behind only the values and a trace of base metal. Remember, the values will now be converted to dark mud in the container------don't discard that part. 

Harold


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## Quirkzunc (Oct 25, 2007)

Harold
Thank you for your reply. 
I apologize for not making the low grade nature of the jeweler's sweeps ash that I am dealing with clear.
The kinds of ashes that I am dealing with hear are those of materials such as vacuum cleaner bags, polishing fluff, emery paper etc. These ashes are very high in non-metallic material.
Although it is possible to treat these ashes chemically, I have in the past done comparisons by treating two halves of the same (thoroughly mixed) pile of ashes; One with AR and the other by melting the ashes with flux (2 parts flux to one part ash) I was surprised to find that the half recovered by melting gave a better return than the half recovered using AR. I believed that the reason for this might be that to some extent, some particles within the ash that come from alloys that have a silver content greater than 10% actually become insulated from the AR by the creation of a layer of silver chloride that forms around the surface. I did notice that you have included a nitric acid step before the AR (Perhaps this solves the problem)
The other reason why the treating of these ashes using AR is a problem for me is that I am required to pay customers out on their returns and there are many customers. Individual treatment of ashes in this way would be impractical for payment purposes.
Please correct me if I have not thought this matter through properly.
Regards
QZ


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## goldsilverpro (Oct 25, 2007)

Lots of that stuff will run higher than you think. I assume what you call polishing fluff is what I call buffing dust - a mixture of thread from the wheel, buffing compound, and gold. If only gold objects have been polished (no silver or PGM's) the untreated dust can commonly run $200/pound, or more.


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## mwren (Oct 29, 2007)

What I beleive you are looking at is tiny pieces of either Tungsten Carbide or Titanium Nitride burs. Also, you will sometimes find non-magnetic polishing media in the older vibratory tumbler machines.


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## aflacglobal (Oct 29, 2007)

Welcome to the forum mwren.


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## Harold_V (Oct 29, 2007)

Quirkzunc said:


> I did notice that you have included a nitric acid step before the AR (Perhaps this solves the problem)



If no pretreatment was accomplished prior to AR application, I'd have to agree------your recovery isn't likely to be very good. Not only from silver, but the amount of base metal that is present can often simply precipitate what little gold that goes into solution and it remains in the solids. 

My method of extraction was always accompanied by the addition of a small amount of AR after the expected yield was dissolved. If there were values present, the AR would react accordingly. I'm very comfortable that the system worked quite well, and is certainly less labor intensive than melting such low grade waste, which is very hard on equipment. Without a collector, recovery from melting such material can be a rather disappointing experience. 

There's no ultimate way to process such material aside from the use of litharge, which would likely yield the best possible recovery of all values. Problem is cupelling the lead afterwards. 



> The other reason why the treating of these ashes using AR is a problem for me is that I am required to pay customers out on their returns and there are many customers. Individual treatment of ashes in this way would be impractical for payment purposes.



It isn't for me to say that you are wrong, nor is it for me to tell you how to conduct your business. All I can say is that I processed each and every order individually, and settled accordingly. I found it to be a very easy and useful way to conduct business. Until I got buried in orders, I could turn one in less than five working days. In the end, my expected settlement was seven days. I served more than 60 customers, and was busy with the lab for no less than 10 hours daily, seven days/week. I rarely found time to myself, and had to plan well in advance for a vacation, notifying my customers of any possible delays so they could plan accordingly. Luckily, my time off came during the slow jewelry season----summer. Christmas time, for me, was a nightmare, except for the last couple weeks in December, when benchmen were so busy with getting out the orders that they left the refining for after the holidays. First of the year my schedule got very busy once again. 



> Please correct me if I have not thought this matter through properly.
> Regards
> QZ



There are several schools of thought regards how refining should be conducted. I listened to my customers as they developed, and learned from their complaints. I'm of the opinion that if your system is working for you, you should stick with it. I see no right or wrong in this situation. 

Being dishonest appeared to be top on the list of customer complaints, so I worked hard to treat each and every one fairly. In spite of being painfully honest, there are those that will find fault, and you occasionally lose a customer. It's impossible to defend a position when you've destroyed any possible evidence in the process of refining. 

One situation I recall all too well was when a young fellow with little experience took over the bench in one of the local jewelry stores. He had been using my services for about a year when he sent in an order that included a button of silver (about an ounce) that had discolored and could easily be mistaken for gold. Not giving it the least bit of thought, I refined the lot and returned his rightful share. He insisted that the button of silver was gold----but the evidence was long gone, having been used for inquartation of his own material. He was one of the six customers I lost over the span of 20 years. 

You can't win them all, but you can try! :wink: 

Harold


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## Irons (Oct 29, 2007)

asking them not to include metallic items that are not precious metals if they can help it.

It's probably not intentional on their part, but with the value of Gold about to hit $800US an ounce, there might be unscrupulous people that might salt ther lots with base metals. The result is everyones' returns are diminished except for the one that does the salting.

It might not be a bad idea to do spot checks on individual customer lots to see if anyone is cheating.

Around here that's called Fraud.


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## Harold_V (Oct 29, 2007)

None of that matters when you run individual batches. The yield is based on recovery, so anything added to the mix that isn't of value does nothing aside from complicate refining. 

The same thing should apply in this case. Adding base metals doesn't matter if a button is assayed after recovery by the melting process. I'm assuming it's the findings of the assay that provides settlement, not the gross weight of the button. 

I always encouraged my customers to send everything. They paid me a fair price to refine their waste materials, and I knew far better than they did what could be processed, and what could not. I suggested to them that it was part of my duty to handle anything that had been in contact with gold. That includes sending saw blades. They often gave up gold after incineration, gold that might have been tossed with the blade had they not been heated. All magnetic particles removed after incineration were abraded well in a mortar, then removed with a magnet once again, and placed in the stock pot. Dust left in the mortar was included in the lot for extraction of values. The chance of discarding anything of value was virtually eliminated. 

Harold


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## Quirkzunc (Oct 30, 2007)

I very much appreciate your detailed reply.

I can see that your method certainly would have removed any problems that might result from the presence of stainless steel in the ashes. I can also see that it should also bring about superior returns.

You must have had some good apparatus to do your Nitric acid and AR leaching of these ashes in. Do you happen to have pictures of any the vessels that you used?

QZ

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## Irons (Oct 30, 2007)

A former Gemologist associate of mine learned the trade from his father who had been a jeweler to royalty in Europe before the War and later worked for Harry Winston in NY.
His father told him the two most important things was to never criticize the customer and always act and dress impeccably. His father always wore a suit, even at family picnics.


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## Harold_V (Oct 30, 2007)

Quirkzunc said:


> You must have had some good apparatus to do your Nitric acid and AR leaching of these ashes in. Do you happen to have pictures of any the vessels that you used?
> 
> QZ



As a boy, I had a fascination with the chemical industry. I recall having a catalog and reading through it like most kids did their "funny books". 

Reason I mentioned that is I used almost nothing but lab ware for refining. It satisfied that part of me that was never fulfilled. I didn't get an education, and I didn't work in the chemical industry aside from refining. 

We've all seen pictures of Griffin low form beakers, which were the mainstay of my refining process. Beakers that were used for preliminary operations were not used for precipitation, otherwise it was difficult to remove the fine gold, which is well attracted to, and adheres rigidly with, scratched surfaces.

For large volumes, I used 4,000 ml beakers, and graduated downward. I had them as small as 25 ml, but used 1,000, 1,500, 2000, 3000, and 4,000 ml beakers for most operations. 

I'm not suggesting it's the "best" way to go, simply stating that those were my choices, and they served me well. 

Harold


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## Harold_V (Oct 30, 2007)

Irons said:
 

> A former Gemologist associate of mine learned the trade from his father who had been a jeweler to royalty in Europe before the War and later worked for Harry Winston in NY.
> His father told him the two most important things was to never criticize the customer and always act and dress impeccably. His father always wore a suit, even at family picnics.



Heh! 

I sort of violated those rules. 

I was quick to point out problems that were created at the hands of customers, but treated them with proper respect. Some of my customers were people that had little, if any, formal training, and often had terrible habits regards their handling of precious metals. One of them had to be educated in the ways of melting. He had a policy of starting out with a large amount of alloyed gold, which would get melted time and again as it was consumed. I explained to him that each heating of the metal lowered the overall quality, eventually yielding castings that were filled with inclusions, a result of oxidized base metals. By using small amounts for each casting, and including the sprue from the previous casting in the succeeding casting, all of one's gold can be used without having the problems, or requiring refining. Alloyed gold is often refined for no other reason than the fact that it has been degraded by repeated melting.

Regards appearances, it's likely we came from different times, under very different circumstances. 

It was not uncommon to find me looking like the bottom of a bird cage. I made personal deliveries of my products, and looked very much like a person bordering on poverty. I wore only work uniform clothing, which was commonly discolored from acid splashes. Aside from the handgun I wore at my side, you could have easily considered me a vagrant. That was a decision I made early on-----with security as a driving force. 

I'm not suggesting, not for a moment, that anyone else should emulate what I did. It worked for me-----because the majority of my customers had been referred by others that had already used my services and were well satisfied with my work, and knew that my appearance was not representative of many that look similarly, but are deadbeats. It could easily be said that many of my customers didn't necessarily like me as a person, but they respected what I did for them. 

I am not against anyone looking good at all times, but I'm also proud to tell you that I do not own a necktie, and haven't since leaving the Utah National Guard in '62. It's not my style. 

Oh yeah! For the record-------I shower daily! :wink: 

Harold


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## aflacglobal (Oct 30, 2007)

> I am not against anyone looking good at all times, but I'm also proud to tell you that I do not own a necktie, and haven't since leaving the Utah National Guard in '62. It's not my style.



Same here. They don't pay me to look pretty. God, some of them pencil necks make me mad. I met a guy last week who couldn't help but tell me how wonderful his shoes and suit and blah,blah, blah felt. Then he procedes to go into how much he paid and Blah,blah,blah. 

Dude, that's need to know information, and i reckon i don't need to know.
Dam Jerk. :shock:


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