# Question about smelting



## yonderfishin (May 16, 2012)

When smelting black sand , and the firing is complete , if you just pour the contents wont any gold at the bottom just get all mixed up in the slag again ? How can this be avoided ?


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## nickvc (May 16, 2012)

A cone mould will be your friend here, basically as you pour the molten charge the heavier elements sink to the bottom, gold for instance, while the lighter elements such as your fluxes and dross will rise to the surface and the shape of the mould allows the gold to form in a small area. I'm not sure how successful melting black sands will be as Im no expert on minerals or ores but I'm sure one of our resident miners will give you advice as to it's effectiveness.


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## yonderfishin (May 16, 2012)

Yeah Im gonna have to get a mold. Anyone have any ideas on an "improvised" cone mold , rather than buying one ?


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## MysticColby (May 16, 2012)

If you have a block of graphite, you can use a standard drill to just drill a partial hole (depending on your volume, this probably won't be big enough)
I've seen where people weld iron into a cone shape as a usual do-it-yourself option.


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## Harold_V (May 17, 2012)

yonderfishin said:


> Yeah Im gonna have to get a mold. Anyone have any ideas on an "improvised" cone mold , rather than buying one ?


Anything that leads towards a narrow bottom is a quantum leap ahead. Give some thought to using a piece of heavy web angle iron, with the ends sawed such that it's wider at the outside edges of the legs as compared to the inside corner. Weld plates parallel to the ends of the legs, which will then become the feet on which the angle iron stands. That will concentrate the values in the bottom, where area is the smallest. 

About the welds----they should be on the outside, not the inside, to avoid creating an irregular surface that can key the material to the mold. 

Before pouring to the mold, it should be well covered with mold dressing (carbon black), and preheated beyond the boiling point of water. 

A true cone mold is in your best interest. One made of ductile iron is highly recommended.

Harold


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## yonderfishin (May 17, 2012)

Thanks for the help so far. Another question , are collector metals still necessary if you stir the melt a few times during the process ? Seems like even if there was just a small amount of gold present it would work its way down to the bottom of the crucible and collect there as you stir it. Id like to avoid cupeling if necessary and it looks like either cupeling or aqua regia would be the only option for seperating the gold from any collector metal used.


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## Harold_V (May 18, 2012)

yonderfishin said:


> Thanks for the help so far. Another question , are collector metals still necessary if you stir the melt a few times during the process ?


Stirring may or may not help. What really makes the determination is how viscous the slag becomes. It can be thinned with fluorspar to the consistency of water, but that approach is hard on crucibles, even the furnace, if you have any spills. 



> Seems like even if there was just a small amount of gold present it would work its way down to the bottom of the crucible and collect there as you stir it.


Yes, it seems like that's the case, but it's not. Just like things aren't nearly as heavy when suspended in water, so it is with gold. In spite of its specific gravity, a viscous slag will quickly overcome its ability to settle as you suggest. It's all the easier with silver, which I've seen in thick slag. Key to recovery is to thin the slag and use a collector. 



> Id like to avoid cupeling if necessary and it looks like either cupeling or aqua regia would be the only option for seperating the gold from any collector metal used.


It may look like that to you, but it's not the way it is. What you need to do is spend more time reading. First off, for the home refiner, using AR to recover gold isn't recommended, although there are some cases where it's the answer to the problem. Cupelling is not typically applied unless you are dealing with lead. You are left with parting with nitric, which is a very acceptable way to recover gold. The process can involve the use of copper as a collector, but we try to promote the use of silver instead, as it requires far less nitric to part, plus if you refine silver, that's one of the steps in raising its purity, in preparation for the silver cell. Study Hoke, paying strict attention to inquartation. That should help you understand how you separate gold from base metals. 

Harold


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## yonderfishin (May 18, 2012)

Harold_V said:


> yonderfishin said:
> 
> 
> > Thanks for the help so far. Another question , are collector metals still necessary if you stir the melt a few times during the process ?
> ...




Thanks Harold. I just found Hoke on the internet. Most available flux mixes and recipes have lead in them. The flux the mocrowave kiln guy uses has no lead but Im trying to find out from him if he uses any collector metal in it at all. There are a few people selling flux that "claim" there is no collector metal needed with their flux but I am way to new at this to spot a lie if they are telling one. Wouldnt using silver be more expensive ?


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## yonderfishin (May 18, 2012)

I just got an answer back from the microwave gold kiln people , they say their flux uses magnesium dioxide and there is no need for cupeling , but you need about 1/3 of the concentrates to be visible gold or it wont work. I guess I wont use their flux.


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## Harold_V (May 19, 2012)

yonderfishin said:


> Wouldnt using silver be more expensive ?


More expensive if you must buy, yes, but it gets reused with little to no loss, and in the case of the platinum group, it becomes the carrier, with recovery of values from the slimes from the silver cell. The point is, if you work with scrap gold, or even ores, you're going to encounter silver---it goes with the territory. Don't sell it. Use it as a tool, and allow it to build up. The savings achieved by the much lower consumption of nitric makes it a real bargain, even if you have to buy some to accomplish your mission. You still have it in the end, it's not like buying a tank of gas for your car. Remember, even if you lose an ounce of silver in the process of collecting an ounce of gold (you won't), you're still leaps and bounds ahead, as silver is relatively valueless as compared to gold. 

Harold


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## Oz (May 19, 2012)

Spot on Harold.

Sometimes being pennywise is pound foolish.


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## kurt (May 19, 2012)

Try Action Mining - www.actionming.com - for your flux & cone mold - they have a good selection of stuff needed for PM recovery, refining & assaying for reasonable prices

Kurt


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## yonderfishin (May 19, 2012)

Harold_V said:


> yonderfishin said:
> 
> 
> > Wouldnt using silver be more expensive ?
> ...




I will look into the silver. Unfortunately , on such a shoestring budget , I may have to do twice the work but I cant really put much $ into this endeavor. Maybe after I am finished removing the bulk of the iron from the concentrates I will wind up with a better ratio of gold to material and it wont be as much of an issue. But Im glad you guys are around to learn the right and best ways to do all this from.


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## Geo (May 19, 2012)

have you tried a piece of corrugated pipe? take a piece of solid (no holes) 4" corrugate drain pipe about 3-4 foot long and cut it length wise to make two halves. fasten one half to a board the same length with a screw in each end and maybe one in the middle. set it up at a 30° angle. put a tub under the end as a catch basin. run a water hose to it with a good stream of water down the pipe. feed the black sand in the stream at the top of the pipe with a spoon. adjust water flow, angle of pipe or rate of material feed until you have the material moving down the pipe and not piling up in the riffles. this is a cheap and effective way of concentrating black sand concentrates.

with a catch basin, you wont lose any material and will need to run through several times to get most of the gold if its flour gold.


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## bswartzwelder (Sep 15, 2012)

I purchased the microwave gold refining equipment, but have yet to use it. I am not recovering from the knee surgery on my right knee as fast as I was recovering on my left knee replacement and it has slowed my recovery process drastically. 

The people where I bought the microwwave gold kiln sent an MSDS sheet along with everything else. Unlike the people from Shor who sent a worthless piece of paper they called an MSDS (no surprise there). However, the MSDS from the microwave gold people listed four ingredients in their flux. Sodium tetraborate > 70%, Sodium Carbonate < 10%, Silica < 10%, and Manganese Dioxide < 10%. NOTE: The actual MSDS lists Manganese Dioxide and NOT Magnesium. Don't know if this makes a difference or not, but just thought I'd pass it along. Harold, your comments are always welcomed.


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