Fuzz Button Interconnects, need some advice _cementation_

[4metals]

If you follow up your copper cementation with scrap iron you can recover copper. It's not clean but I have a client in Texas who does it and when he gets 3 or 4 drums of dried powder he fires up the big gas furnace and casts bars. They told me last time he melted, he got $2.75 a pound for the copper from a scrap yard. A drum held over 400 pounds of the dry copper which they dry on the roof in the summer.

 

[kurtak]

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

If you are asking how much it cost me - nothing - when I cut bus bars to length for cementing &/or when cutting the solder joints out of copper pipe I am scrapping I clamp the bus bar or pipe in a vise & use my sawzall with a fine 24 tooth hacksaw blade to cut them & I put a catch pan under it to catch the copper chips/shavings figuring I could always use it as a collector metal in smelting - but I tend to use silver as my collector metal so the copper chips/shavings have just been adding up - got a couple coffee cans of it

so now for this purpose it's just a matter of sifting it with my 80 mesh screen to remove the over size from the -80 ---- it looks like it's about 50/50 over size/-80

Kurt

 

[kurtak]

If you follow up your copper cementation with scrap iron you can recover copper. It's not clean but I have a client in Texas who does it and when he get 3 or 4 drums of dried powder he fires up the big gas furnace and casts bars. They told me last time he melted, he got $2.75 a pound for the copper from a scrap yard. A drum held over 400 pounds of the dry copper which they dry on the roof in the summer.

yap - me to - I don't produce it by the drum full but I follow the same procedure --- I use my old crucibles that I figure only have one or two more melts left to them - if they (the crucibles) were used for PM melting - then before I melt my copper I clean them with soda ash & pour to my cone mold as follows

near end of life crucible
(1) load with soda ash
(2) put in furnace & melt soda ash
(3) pour to cone mold
(4) reload crucible with copper cement
(5) put in furnace to melt copper
(6) pour copper bar
(7) sell to scrap yard as "red" brass (higher grade then yellow brass) about $2.50 - $2.70 a pound

Kurt

Edit to add --- when loading the crucible with soda ash it's a good idea to add some copper to the mix as a collector metal - this will help in the metals settling to the bottom of the cone mold

 

[4metals]

(1) load with soda ash
(2) put in furnace & melt soda ash
(3) pour to cone mold

Interesting. I would question the fluidity of using just soda ash to flux, I would prefer to see borax, soda ash, and fluorspar as a thinner. It would increase your chances of having the metal collect in the cone mold.

Another technique is to do a copper wash, just add a bit of copper to act as a collector. If you have a silver cell, use sterling or some other high silver content scrap. (85%)

Back in my refining days I did a copper wash whenever a customer was coming in to watch so there was no residual metal in the crucible. (Refiners rule #1, never give your metal to the customer!) I just kept using the same 50 ounce cone chunk of copper over and over and when the values built up it was put in for refining.

 

[kurtak]

4metals

I need to express my thanks for the heads up on the two methods ("fine" copper powder/stirring - or bus bar/bubbler) for cementing PGMs

At this point I have tried the fine copper powder/stirring method (using my -80 mesh copper) on about 1 liter of solution & am "very" pleased with the results

I had about 200 ml of very concentrated Pd/Pt solution that also contained a high percentage of base metals (more then 50% BMs) so I added my dilute Au stock pot & dilute PGM stock pot to that which brought it up to about 900 ml

I put the beaker on my stirrer/hot plate with stir bar in the beaker & turned the heat on the #2 setting - once the solution came up to temp I turned the stirrer up to the #7 setting & added about 1.5 grams of copper powder --- The AU dropped almost instantly (tan/cloudy) & what was interesting was that the Au after a couple of minutes of stirring balled up into little clumps

using the -80 mesh copper it would take a bit of time for all the copper to dissolve - about 7 - 10 minutes at first & about 45 - 60 minutes towards the end (so I can see finer copper working really well in this process)

The pic is the results of the recovered powders along with a "small" sample of the powders dissolved in AR 8)

I am very pleased with these results as it only took about 6 hrs (adding copper a little at a time & waiting for each addition to fully dissolve) & the resulting recovered powders are "very" clean compared to past attempts of cementing PGMs without the aid of agitation

The solution is still testing a light hint of PGMs (light green/light orange) with stannous so it will go to a stock pot & when I have a couple of gallons of low concentration solution I will try the bus bar bubbler method as well

again thanks for the heads up

Kurt

 

[kurtak]

(1) load with soda ash
(2) put in furnace & melt soda ash
(3) pour to cone mold

Interesting. I would question the fluidity of using just soda ash to flux, I would prefer to see borax, soda ash, and fluorspar as a thinner. It would increase your chances of having the metal collect in the cone mold.

Another technique is to do a copper wash, just add a bit of copper to act as a collector. If you have a silver cell, use sterling or some other high silver content scrap. (85%)

Back in my refining days I did a copper wash whenever a customer was coming in to watch so there was no residual metal in the crucible. (Refiners rule #1, never give your metal to the customer!) I just kept using the same 50 ounce cone chunk of copper over and over and when the values built up it was put in for refining.

I wanted to comment on this & sorry for the delay - got quite busy the last couple days

I have found that straight soda ash works quite well - it tends to run more fluid then a mix of borax & soda ash so no real need for the fluorspar (though a bit added certainly doesn't hurt)

I actually got the idea of using just soda ash from Harold suggesting using it to clean melting dishes (figured if it works on melting dishes - why not crucibles)

The other thing about just soda ash is that it is soluble in water where as borax is not - so I take the soda ash slag & crush it up & then boil it in a kettle of water which in turns make for easer recovery of the ball metal hung up in the slag --- where as when borax is in the mix boiling the slag in water only brakes it down leaving a lot of duff thereby making the ball metal recovery more difficult

And yes - adding some copper as a collector is also a good idea (& I should have said that) don't need a lot - just enough so you get a good settling of metal in the bottom of the cone mold (will go back & edit my post to add this info)

I do use the flux mix of borax/soda ash/fluorspar when actually smelting but don't see the need for other then soda ash when cleaning a crucible

Kurt

 

[4metals]

It has been a while since I had to buy fine copper powder so I figured I would check out some pricing. I think we are all crazy refining precious metals that sell at a few cents over spot price, we should be melting clean copper and making dust. We're in the wrong business!

 

[kurtak]

Indeed - the problem is the demand for it is in specialized industrial application markets - the few local private buyers I have that will pay me a little over spot for PMs aren't going to buy copper powder for 5 or 6 times spot price & the scrap yard won't buy it at all - has to be melted into bars

you have to play in this ball game - http://www.copper-powder.com/

for my needs I will make my own :mrgreen:

Kurt

 

[jason_recliner]

One thing I'm missing on cementing.

Say I have some gold in solution. I know it's in there because it's nowhere else and it's been there for months from a previous failing. Though it seemed to partially precipitate and settle for a few days, once I added some heat to speed things up, what powder did settle is all gone again. A little more SMB made nothing happen.

I know this is going to be because there's still excess poor man's nitrate in it. A stannous test (3 days old) comes up blank - reasonable under the circumstances. Unfortunately I've got no other gold at the moment to make a solution to reverse test my stannous with, like I advocate so much. (I reverse tested my first stannous batch when I wasn't sure what was going on. It was a proverbial lifesaver. But I had a jar of good gold solution at the time, and now I don't.)

So I decided to cement it all out with copper and start over, which is the advice I received once before. Minutes after dangling some copper in, the solution starts to turn a dirty brown. Promising!

But how does one know when the cementing is finished? Ms Hoke's answer is "when it doesn't test positive for gold", which is not so helpful if it didn't in the first place.
Since copper in acid will become copper chloride, won't this keep chewing out the, ahem, busbar * while producing copper chloride I powder on the bottom? Would that be a definite end, when I can see white powder appearing? If I were to add the bubbler, I'm only further strengthening the CuCl to take off more copper metal, right?

Right now, about 5 days in, it's an almost black solution with pale brown powder on the bottom. But I don't know how much to expect.

This is where Harold's gold button would really have come in handy. Or anyone's for the matter.

* Speaking of busbars. My 2 lb block of bright, clean copper happens to be spectacularly annoyingly 5mm too wide for my current precipitating jar. I'm having to carefully use 10 thou shim strips, fed in very slowly to avoid 'derelict debris'. Not really a suitable material. I swear I will get proper beakers once I see some real gold come out of my playing.

 

[Harold_V]

If all else fails, clean a short piece of copper wire with fine abrasive cloth, so it's nice and shiny, then dip it in the solution. If there's any values present, you should see them form on the surface. If, however, there is no reaction, or if the copper simply dissolves, leaving behind an etched surface, it's pretty safe to assume that you have recovered all the values.

I would think that you have more than enough copper present, and that there is some remaining. If that's the case, unless there's something VERY unusual going on, you can safely assume all values are down. The only reason they may not be would be because you introduced a very small amount of copper and it is taking a lot of time to cement the values. Do remember, it must come in contact with the copper in order to cement, so the greater the surface area you provide, the faster will be the recovery.

Harold

 

[jason_recliner]

Thanks for that tip Harold.

It sounds like black dust on my foil is my indicator. Yes, still forming I think. It had an interesting wavy pattern tonight.
This solution is a lot weaker than normal people's. So it'll take longer.

And I forgot to add that this is only a portion of it, to try the theory. No point ruining all of it. So it'll take even longer.

 

[4metals]

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