99.5%? Is it possible?

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melt time to get from bars to molten 5 - 10 minutes
atomizing 2 t.o/second
settling, majority 15 minutes, balance 24 hours
digestion 30 minutes
filtering chlorides (about 85 gallons acid) 30 - 45 minutes
PGM Drop 5 minutes*
filtering again same as before
gold gassing 45 minutes
filtering again
washing gold 15 minutes
melt and pour 400 oz bars 30 minutes


total time around 6 hours


* if Pt , Pd is low in concentration it takes longer to re-settle and filter than it's worth, most want to ship their gold and be paid for it within 24 hours so cementation and collecting when it accumulates is a better use of time.
 
During my trip, and due to the introduction of "the atomizer", the obvious question kept popping in my head:

Can gold of sufficient purity be quickly produced using only "the atomizer" followed by some carefully designed fluxing and/or salt cementation method?.

Have you done any experiments in this direction 4metals, anyone?.

I think it could work well if there are no PGMs in the feed, maybe with more than 1 atomization in the sequence. No aqueous treatments has a nice appeal.

I wonder what Vanoccio Biringuccio could have achieved in terms of fineness, had he had access to an atomizer... :shock:
 
Interestingly enough, I am working with atomization on sterling silver for that same purpose. My logic is that by adequately fluxing the sterling and taking advantage of the huge surface area, and the ability of the fluxing materials to contact the majority of the material, the copper can be oxidized out of the alloy. I doubt you could ever get it all so that's why I never considered karat material.

Once the material melts most of the fluxing action is at the surface of the metal pool that is why the contact between the atomized metal and the flux is so important. If the metallic copper doesn't oxidize early on it may not go, so determining flux to atomized karat ratios are paramount to success. That is what I'm working on now.

With proper fluxing, enough copper can be removed to produce an alloy that has low enough copper to run in silver cells easily without the "copper buildup blues."
 
Very nice. I think "the time spent at a high temperature but below melting point" is likely a very important parameter. As you say, as soon as the material melts, the flux action is greatly diminished and confined to the surface of the melt.

These middle age guys were bringing gold from 37% to 90%+ in one pass using table salt, urine, and crushed brick...and no atomizer...so I think the idea has some merit.

You, yourself have used scavenger fluxes on leached inquarts to bring 99% gold to 9995 with great success, so there is only that band from 90% to 99% to bridge the gap.

In my head it is possible. Just need to do the experiments...sometime.
 
I see. It makes sense. Definitely hard to beat the atomizer for exposed surface area and speed of reaction.

Have you timed the time for a leach of an atomized gold-silver inquart in hot nitric?. It must be almost explosive-fast. It is probably very fast too with sulfuric acid. Different application. Sorry to digress. :oops:
 
Atomized inquart would be too violent and too fast in Nitric. When I do inquarting I use a scrubber designed to regenerate nitric in an O2 rich atmosphere, since retention time is critical in the design of a scrubber the reaction rate has to be considered. The inquarted silver is usually digested in coarsely grained shot for that reason.

I'm afraid atomized inquarted alloy would break some glass!
 
Atomized inquarted alloy digested in sulfuric acid in a heated cast iron kettle sounds like a very expedite, simple and economical solution for material without PGMs. Only issue is that the price of silver is not what it used to be, and large lots need much metal, larger furnaces, etc.

Your HCL-Chlorate process with atomizer is very hard to beat for an all-in-one economical and fast solution. Maybe only if the fluxing experiments work out and only if no PGMs.

I'd say that the atomizer is the biggest innovation in a very long time.
 
Several methods are described in this book with many diagrams and charts.


http://books.google.com/books?id=6aP3te2hGuQC&pg=PA102&lpg=PA102&dq=atomizing+precious&source=bl&ots=wO2MEMO__b&sig=XZC7n4C50XGAtf3H5f-1b70FN9o&hl=en&ei=LqexTIUXi_6cB-j5oJsG&sa=X&oi=book_result&ct=result&resnum=1&sqi=2&ved=0CBIQ6AEwAA#v=onepage&q=atomizing%20precious&f=false
 
Excellent book, and worth the $280 price tag if you are considering building your own atomizer. It took a month for my copy to arrive, I doubt it's because everyone's reading it, more like they had to dust it off to find it.
 
I had no idea this was in your library. 8)

I take it atomizer tanks are included in the refineries you consult for. There is one thing I wasn't clear on.

Is the water recirculated through the high pressure pump, or the tank sized to accommodate the additional water.

If the water is recirculated what sort of filter is used to keep the pms out and how much material is tied up in the filter?
 
Generally the water is not recirculated, although with a large enough holding tank it could be. The processing lot size determines everything, smaller units will atomize 2 oz of karat per second using 4 nozzles pushing 1.4 gpm each at 5000 psi. So to atomize 1000 oz, you will generate about 50 gallons of water, that requires a tank holding about 75 gallons because if you don't allow a few inches of water in your receiver to start, you will be spending time scraping gold off the bottom!

The tanks I like to use will accommodate the full volume water needed, then it can settle overnight and be pumped down in the morning. The water could be re-used for the next lot if you use a shallow well pump to feed the pressure pump. If you need to process immediately all but 2 ounces of a 1000 ounce lot settle within 5 minutes. Within 24 hours it's all down.

I prefer not to filter it because the super fine particles work their way into the fiber of the filter media requiring incineration and all the associated processing and accounting.
 
4metals: I understand you melt with an induction furnace. How do you heat the ceramic nozzle/crucible with a hole for the trickling molten metal or did you put a ceramic tap on the bottom of the induction crucible?.

Thanks for posting the exact specs of the atomizer.
 
The orifice (tundish) is mounted in an induction heated head. Small melts op to 1000 oz can be melted in the tundish which is plugged with a removable rod to start the flow, larger melts are accommodated by pouring at a controlled rate into the heated tundish.

I suppose a small unit could be fabricated from an electric kiln, with a hole in the bottom to drain into the spray and a top that opened to feed it. This would suffice for karat gold and smaller melts, feeding from the top would be possible I guess.
 
http://en.wikipedia.org/wiki/Tundish

In modern use, a tundish is a broad, open container with one or more holes in the bottom, used in various industrial processes. In metal casting, the tundish is used to feed molten metal into an ingot mould so as to avoid splashing and give a smoother flow.

The tundish allows a reservoir of metal to feed the casting machine while ladles are switched, thus acting as a buffer of hot metal, as well as smoothing out flow, regulating metal feed to the moulds and cleaning the metal.

Metallic remains left inside a tundish are known as tundish skulls[1] and need to be removed, typically by mechanical means (scraping, cutting).
 
What is the material the "tundish" you use made of and what do you use as a rod/plunger to close the drip hole?. Any chance of a quick hand drawn diagram or a picture?. :p

Can Platinum scrap be "nuked" with this type of atomizer in your opinion, or melting point is too high?. :shock:
 
The tundish is a continuous casting crucible which have the hole and the plunger. Off the shelf stuff, all sizes available.

IMG00023-20100729-1639.JPG

Platinum is difficult and I haven't worked with it as a high grade metal with this application, however I have "inquarted" platinum in karat scrap 3:1 and atomized it effectively. The chemistry used after atomizing lends itself to PGM recovery nicely.

The long standing issue with platinum is its difficulty in digestion for high grade material, the above inquarting scenario addresses that nicely.
 
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