Fuzz Button Interconnects, need some advice _cementation_

okay, back a while ago, I found a bunch of fuzz button interconnects... like the ones from this thread: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=34&t=16018&hilit=fuzz+button&start=20

after doing some research on them, I was figuring on Be/Cu/Au wire was most likely what I was dealing with. It would appear that is not the case. Here was what I did... please keep in mind that I'm still pretty new to this and was not expecting what happened to happen:

1 - started with 4.5 grams of gold fuzz buttons in a clean beaker
2 - added about 50mL DI water (not tap water) and about 8mL Nitric (70%)
3 - let this solution sit over night. when I came back in the morning, the liquid was a clear deep burgundy red. I was extremely surprised. gold wire was still present on the bottom of the beaker and no other precipitate existed.
4 - poured off the liquid into another beaker and washed the remaining springs with DI water until the washes ran clear. added all washes to what I poured off.
5 - not knowing what occurred with the first nitric bath I set it aside and I proceeded in trying to recover just the gold by dissolving in aqua regia. I covered in about 50mL of HCl (32%) and immediately the acid turned burgundy red again.
6 - added 3mL of Nitric Acid and let the solution sit for an hour.
7 - upon return, all the springs were dissolved and the solution was still deep read... the solution was slightly cloudy but everything was dissolved, no precipitate was noticed on the bottom of the beaker.
8 - knowing the gold was in this second solution, I kept it separate from the first leech. I added a pinch of Sulfamic Acid to neutralize any extra nitric and let the beaker sit overnight.
9 - not knowing why the red color was in solution, I got my stannous out and tried testing against a gold solution.... nothing. Started making a fresh batch of stannous and let it do its thing overnight as well.
10 - went home, scoured the forum for some hints/ideas/clues to what was going on
11 - When I got back the next evening, I tested my stannous against my gold solution, got a strong purple reaction.
12 - tested the first solution (the one that should not contain any gold) and the swab turned nearly black with distinctive dark green around the edge... holy shnikey, what's Palladium doing in there?!?!?!
13 - turned my attention to the second solution and added SMB to precipitate the gold out. The gold dropped very fast and the left over liquid is still burgundy red. DID NOT test this solution for pd yet and I ran out of time and had to wait overnight for the gold to settle. Will test this solution the next time I get a chance.

and so that is where I am at the moment. I was not expecting palladium at all... In my research, I saw info about Be/Cu, Co/Ni, and Au plated alloys, but nothing with palladium in it... not one lick of info. So my question is this, is there anything that I have done to give me a false positive? Does anything look off to you guys with experience? Has anyone else who worked with these fuzz button wires run across this?

At this point, I think my next step should be to drop the palladium with zinc or aluminum and set it aside somewhere for when I have a chance to read up on the Pd refining process. Would this be advisable?

Any info/insight you can provide would be appreciated. Sorry for being long-winded (it runs in the family) and thanks in advance!

Mike

okay, been doing a bit of research on the site and things are a bit confusing. Here is where I am at at the moment:

First solution (dilute nitic bath): Nothing has been done to this solution yet. I have noticed a very tiny amount of reddish sediment on the bottom of my beaker.

Second Solution (AR bath from which Au has been precipitated with SMB): Tested with stannous, no reaction. Read somewhere that SO₂ could give a false negative so I decided to add aluminum foil (don't have zinc) and collect the precipitate for later testing.

So now I have turned my attention to the first solution. My thinking is that there should be no Platinum in this solution because it was solely a diluted nitric bath. I would assume there is a small amount of other base metals present as well. I would also assume there is still free nitric in solution since I originally added 8mL nitric to 4.5g of starting material. I will test with sulfamic acid when I get back to working with the solution just to make sure.

I have been going over the platinum group metals in Ammen's book and have a pretty good idea on how to proceed. Zinc precip (to separate Pt/Pd from excess base metals), redissolve (to rerifine), ammonium chloride/sodium chlorate (to precipitate palladium salt), then refining/purifying said salt. I have a question about the chemicals to precipitate the salt though. The literature says to use ammonium chloride to precipitate platinum, but if I don't have platinum in solution, can i skip this step? The reason I ask is because everything I have read says 'ammonuim chloride for platinum precipitate' and 'sodium chlorate for palladium precipitate.' But from the chemical reactions I see, it looks like the palladium forms an ammonia complex that is later chlorinated with the sodium chlorate, thus needing both chemicals... is this correct?

Lastly, and this could just be misinformation, is there a way for me to precipitate palladium directly from the dilute nitric solution I currently have? I read some snippits that Pd could be precipitate by DMG (unfortunately I don't have any), but am having trouble finding out too much more about the process. I also read about being able to precipitate palladium from nitric solutions with SO₂, but once again, did not find out much about it. Is the SO₂ method not advisable when there are other base metals present? This route is of interest to me because at the moment I don't have ammonium chloride, sodium chlorate, or DMG... if I could avoid buying $50 in chemicals for 2 grams of Pd, it would be nice. Any enlightenment on this matter would be greatly appreciated.

Thanks again!
Mike

Mike,

You could always cement it out with copper and save it till you have more to refine further.

Dave

I have been considering going that route... figured it was a good excuse to do some research and studying and maybe expand my knowledge base a bit

Mike

You will be best served by setting your Pd/nitrate solution aside (on the shelf in a sealed jar) until you can get the proper chems to precip PGMs as their salts & in the case of Pd dissolved in nitric you "need" DMG (which you should have anyway to test solutions for Pd &/or to confirm that a stannous is indeed Pd)

Ammonium chloride/sodium chlorate don't work to precip PGMs from a nitrate solution - they are used to precip Pt & Pd from a chloride complex solution (AR or HCl/CL)

Cementing is only a "recovery" process not a refining process - so it is like taking a step backwards

You mentioned maybe trying to cement it using aluminum --- that won't work in this case - why - because your Pd was dissolved in nitric & though aluminum is higher on the reactivity series aluminum does not react with nitric so it will not cement anything from a nitric solution --- in fact that is one way of testing if a piece of metal is die cast (zinc) or aluminum - zinc (die cast) will react with both nitric & HCl where as aluminum will only react with HCl but not with nitric

If you cement with zinc you are only going to recover the Pd along with base metals which puts you back to square one of re-dissolve in order to precip with DMG or sodium chlorate - so you don't really gain anything

Like wise - cementing with copper is "only" a recovery method (your Pd is going to be contaminated with copper) which puts you back to square one of re-dissolve in order to precip with DMG or sodium chlorate - besides that - cementing PGMs with copper is not like cementing silver with copper --- when cementing silver the reaction happens fast & the silver falls away from the copper thereby keeping the reaction going --- that's not true with Pd &/or Pt --- Pd & Pt will start to cement when you add the copper but it forms a "tight" bond on the copper which prevents the acid from getting to the copper to continue the cementing process & though it doesn't completely stop the reaction - it slows it waaaay down - it can take a couple of weeks to work & the result will be "much" copper flaked off with the Pd - In fact you will end up with more copper then Pd by the time all the Pd has come down out of solution AND some of your Pd (or Pt) is going to remain on the copper in a tight bond

It's a different story when there is "some" PGMs in a mostly silver nitrate solution - then the reaction between the copper & the silver nitrate is happening so fast the PGMs don't have time to form the tight bond on the copper so they come down with the silver

If you just want to recover the Pd to refine later then I would use zinc - other wise set the solution aside & wait till you have more PGMs to work with & the Chems for doing selective precipitation of the PGMs

Kurt
_cementation_

Here are a couple of pictures concerning cementing PGMs with copper - one is the copper used for cementing - the other is part of a bar of the metals cemented from a PGM solution with copper (I cut a small slice out of the middle of the bar & sent it in for an XRF read out)

Notice how coarse & bumpy the copper is - that because after the PGMs form the tight bond on the surface the acid does "slowly" work on the copper under the passive layer of the PGMs bonded to the surface - & in the process it flakes off large bits of copper --- also note the black on some of the copper - that's PGMs bonded tight to the surface of the copper where the copper was setting on the bottom of the beaker & the acid couldn't get to it to react as well

the results of the XRF cement recovered metals melted & poured into a bar are as follows (by percent)

Cu 61.01
Pd 17.11
pt 12.16
Sn 4.38
Sb 2.84
Rh 1.00
Bi .85
Ni .66

As you can see cementing PGMs with copper does not work well --- I have tried it in concentrated solutions - dilute solutions --- with heat - without heat --- with free nitric - without free nitric (copper does not react with HCl - it needs an oxidizer like nitric or H₂O₂) --- all with the same results - which are poor

Maybe that's why Harold always talks about using iron for cementing his stock pot (I have always wanted to ask him why iron instead of copper - just never got around to the question) & for that matter why iron instead of zinc

Kurt

Kurt,

Thank you for the reply and the helpful insight!

This batch caught me off guard and I was in no way expecting to see Pd in my solutions... nor am I in anyway prepared to refine it. Heck, the only things I have refined so far have been gold from fingers and, most recently, bga chips. Just another lesson that reaffirms to always test your solutions! I will looking into obtaining some DMG for this and testing. And if all I have to do is add it to my nitric solution and collect the salts for processing later, I think I can handle that.

Thanks again!
Mike

As you can see cementing PGMs with copper does not work well

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Please give us some details as to the source of your copper, the details about your waste acids, and how you suspend your copper in the acid as well as how you provide agitation.

Copper is very effective at removing values from acid, it has been classically used for this purpose for many many years. There are circumstances where it is not as effective as possible but these are always for a reason. We should try to figure out why it isn't working effectively for you.

mls26cwru said:

I don't have ammonium chloride, sodium chlorate, or DMG... if I could avoid buying $50 in chemicals for 2 grams of Pd, it would be nice.

Click to expand...

FrugalRefiner said:

You could always cement it out with copper and save it till you have more to refine further.

Click to expand...

kurtak said:

Cementing is only a "recovery" process not a refining process - so it is like taking a step backwards

Click to expand...

I agree that cementation is a recovery process, but I don't see it as a step backwards, or that it puts him back to square one. He doesn't have the chemicals you've suggested and would prefer not to spend the money on them if he can avoid it. I suggested cementation because it meets his needs.

Dave

Investment in a little DMG for testing purposes to assure your cementation is complete is wise. Spending a lot of time to refine 2 grams of Pd (at $25 a gram) is not.

Often concentrating and saving mixtures of cemented values is the prudent way to go.

4metals said:

As you can see cementing PGMs with copper does not work well

Click to expand...

Please give us some details as to the source of your copper, the details about your waste acids, and how you suspend your copper in the acid as well as how you provide agitation.

Copper is very effective at removing values from acid, it has been classically used for this purpose for many many years. There are circumstances where it is not as effective as possible but these are always for a reason. We should try to figure out why it isn't working effectively for you.

Click to expand...

4metals

Thanks for asking as I have posted about this problem a few times in the past - the first time was as a question because I was having the problem when I first joined around 3 years ago - & then a few other times as a response (much the same as my post here) to others that have posted the same problem

First let me say that I only have the problem if it's a "saturated" solution containing a high percentage of PGMs - no gold (chloride solution) no silver (nitrate solution) but may also contain a fairly high percent of base metals (the reason to try cementing - to reduce base metal & recover PGMs for better refining procedure &/or results)

My copper source - I use "only" copper bus bars &/or "large" gauge copper wire so it should be high grade copper & I always clean it on a wire wheel &/or with sand paper before using it to cement with (see pic of my cement copper stash)

My 91 year old dad just called me & needs some help so will post answers to your other question later

Kurt

Recovery from waste solutions or solutions with a high percentage of base metals, you will have other metals (or metal salts) in the solutions reacting or reducing metals or pushing metals out of solutions as colloids or precipitants, you can also expect to have drag down...

In the figures posted, I seen metals that the copper did not cement or would not have cemented from a more pure solution, several of these metals may have been pushed out of solution from another source or reaction, in the "dirty solution of base metals", the copper amount is also high, small pieces of copper or thin copper wires will flake off easier than a large thick clean bus bar (of electrical copper) or another fairly pure source of copper...

Cementing on copper is a recovery method, a good one at that, the more pure the solution you are trying to recover the valuable metals from, the more pure the cemented metal or metals will be, take a fairly pure silver nitrate (and copper nitrate) solution, (from sterling silver for example we can cement a fairly pure silver from solution with washing we can recover a silver of fairly high grade (high enough to go directly to the cell after washing and melting, but if we added in many other metal salts (or possibly even some other organic trash) we may have in waste stream and use copper to cement values and use all kinds of scrap copper of different sizes (or small diameter wire) to do this work we could also expect to find flakes of copper added to this cemented values...

Thanks for the replies guys - & yes correct on all accounts

The bar I pictured & posted XRF results on came from processing anode slime --- almost everything I process comes from the dirtiest hardest stuff to process (e-scrap, contact points, etc.) so I am always dealing with base metal trash

Most of my silver comes from contact points which accounts for much of the trash as well as the PGMs - I also use silver as a collector metal in smelting which accounts for more trash

I only use high grade #1 copper for cementing & "always" clean it good before using it --- so the copper should not be the problem --- "heavy" (8 gauge or larger wire) is "only" used on small volume solutions (as pictured) with the wire size selected being "far" greater then what the acid will consume

But these things don't explain the problems I have encountered trying to cement PGMs (tight bond to copper & copper flake off) from high concentration solutions

Take the anode slime bar as an example - AR used to leach the PGMs from the slime - cement with copper to recover PGMs for refining - I expected the trash drag down due to the dirty starting material - but - it took close to 2 weeks to cement (daily stannous testing) due to the tight bonding problem - & by the time stannous test showed light enough results to justify sending the remainder to the stock pot I had more copper flaked off then all other metals combined - & I have had this problem every time I have tried cementing PGMs from a concentrated solution (the stock pot is not a problem - there "most" of the PMs have been removed & it's no longer concentrated - so yes I still get BM trash drag down (expected) but not the tight bond problem &/or high copper flake off problem

I have tried diluting (by a lot - 3 to 4 time starting volume) same problem --- I have tried heating - same problem --- I have tried adding "small" amounts of nitric (in the hope a "little" free nitric would break the tight bond & keep the reaction going as well as reduce copper flake off) but same problem --- So back to 4metals questions

(1)the source of your copper --- already answered

(2)the details about your waste acids --- I assume you're asking about the stock pot - this is not where the problem is - as explained above

(3)how you suspend your copper in the acid --- two methods based on large volume solution or small volume solution - as shown in the picture

(4)as well as how you provide agitation --- this may (at least in part) be the problem - I have not been providing agitation other then hand stirring from time to time during the coarse of the day --- I have PGM solution currently sitting on the shelf to tackle as soon as I am done with my current silver project so will put it on the good old magnetic stirrer with some copper suspended & see how it goes

I should note that the only reason I have gone with the cementing procedure (instead of chem pricip) is when I am working with really dirty starting material - in which case I am following the advice to recover then refine - if it's relatively clean to start with then I follow standard chem precip procedure

Hope this helps explain it all better & look forward feed back

Kurt

Kurt,

I'm no expert, so I hope 4metals will have some suggestions, but I do have two comments.

I think you're right that agitation may be playing a part. For large volumes, an air bubbler might work well.

I have a technique I've used to clean up silver cement when there is visible copper contamination. After cementation is complete, and I've removed the copper and washed the cement, I've added some distilled water and a tiny amount of nitric acid. The nitric will dissolve the copper contamination. Stir it often, as some silver (or, PGMs) will also dissolve, but the copper will push them back out as it dissolves. You may end up with some of your silver or PGM dissolved in this nitric wash, but if you don't get a heavy hand with the nitric, it should be minimal and you can recement it or send it to the stock pot. The washed metal will be much cleaner. I've never seen this trick mentioned, so it will be interesting to see what the experts think of my idea.

Dave

Cementation depends on a constant supply of solution contacting your copper (or whatever metal you have chosen to cement with) The speed is directly proportional to the contact.

This is why zinc dust acts so fast, the dust is such a high surface area and easily mixed into the solution that it quickly reacts with other metals to reduce them. The only catch is zinc also brings down a lot of base metals.

I have priced -200 mesh copper dust and the price made me wince. I have however atomized pure copper myself and used it for cementation and it is by far the quickest way to do it. And it is because of the physical contact, the greater surface area of the dust brings to the reaction.

Back to reality...... Copper buss or flattened copper pipe is affordable. I like to see the copper hanging in the solution, suspended from a hook as you do with your beaker but with a little help to make it work better. In the sketch below, the copper metal is hanging in the beaker suspended from above, then a length of PVC pipe is placed around the metal. There should be a lot of holes drilled around the bottom circumference to allow solution to flow in freely. The pipe can then rest on the bottom of the beaker and the solution can still flow in. The pipe should be short enough that it is below the liquid level in the beaker so the rising flow from the aeration flows up and over the pipe allowing for new solution from below. The curved line is the air tubing from a good powerful aquarium pump. The size of the pipe should be such that the air bubbles contact and knock off reduced metals clinging to the copper.



The copper will still collect some of the metals it reduces on the bar but the air helps dislodge some of it and it serves to circulate things well.

Try this circulation technique and see how things change.

4metals

sorry for the late response - was busy yesterday pouring anode bars & setting up silver cell

I like the idea of the "fine mesh copper" & had actually thought of trying that using it in small additions at a time to give the acid time to insure full dissolving of the copper between each addition & of course continual stannous testing (& doing it with a low stir on the magnetic stirrer) just never got around to actually trying it --- So I will certainly be giving both methods a try

Thanks for the input - it is much valued on this end

Kurt

The trouble with copper mesh is as one piece dissolves it may leave another unattached to fall to the bottom. The surface area is high but I think it will cause the copper content of the precipitated metals to be high as well. With atomized copper dust I was able to add small increments until there was no PM stain, I do not think copper mesh will afford the same luxury.

If you are going to use a spin bar, I would not use the pipe and just spin it as fast as it will maintain itself. Spin bar mixers can get pricey and a lot of our members who do this as a hobby don't have one. An aquarium air pump is easier and cheaper to attain.

4metals said:

The trouble with copper mesh is as one piece dissolves it may leave another unattached to fall to the bottom.

Click to expand...

4metals

I want to make sure we are talking on the same page --- I am not talking about using a fine mesh copper as in a piece of fine mesh screen or wire - but rather fine mesh in particle size as in the picture

this is screened to 80 mesh - the smallest screen size I have on hand (could certainly get some finer mesh screen though) (the caliper reading is the wire size that fits the screen hole "tight" - it's .009 inch)(sorry couldn't get the pic to rotate)

When I dumped the copper (7 grams) into a 1 liter beaker on my stirrer/hot plate with the stirrer turned up to the #7 setting (anymore then that & the stir bar started doing flip flops) the larger particles do go to the bottom out side edge of the beaker but in watching them they are also continually being lifted off the bottom & thrown back up into the water (which would other wise be the solution) --- also the copper is going to be reduced in size by the acid as it's dissolved

So my thinking is that if I put my PGM solution in the beaker & turn the stirrer on & feed the copper slowly - say 1/2 g to a gram every 15 minutes to half hour this could work :?: --- & I would think a little heat would help here as well

Also can you tell me what the copper to PGM trade off is - or is as simple as a one to one trade off (1 gram copper into solution cements 1 gram PGM out) --- that would help to estimate copper needed on a particular batch (along with stannous testing of course) for this method

I like the idea of this method (as I said I had actually been thinking of it anyway) though I will certainly be trying the fish tank bubbler/bar method as well

And again - thanks for you feed back

Kurt

Using the copper as in your picture should do the trick. The copper I used was dust or -200 mesh but if the spin bar lifts it off the bottom of the beaker you should be fine. Heat always helps but it is generally not used because large refineries treat a lot of solution and heating it up is not practical.

As far as determining how much copper to use it depends on the metal concentrations you are trying to recover and their valence, different solutions have PMs in varying salt compositions depending on the reactions and the compositions of the scrap that generated that solution. So while it is theoretically possible to calculate exactly how much copper for a given solution, the reality of it is to use your stannous as an indicator and add, mix and repeat until you have no PM stain. In a large refinery they would use an ICP or an AA to check the batch before release to waste treatment but believe me you will never pay for the instrument with what you are recovering in this cleanup process. Stannous is the on the spot very accurate test of preference.

What is the price per pound for the -80 mesh copper powder?

For what it's worth, heat will also speed up cementation. When cementing PGMs from solution, I use heavy copper and heat. I know it chews up the copper more and the powder is dirty but it is much faster than ambient temperatures.