Re dissolving and precipitating powders leached

[donnybrook]

Can anyone on the forum advise whether brown or black powders leached and precipitated using either iodine or chlorine be redissolved in AR and again precipitated using SMB.

Donnyb rook Australia

 

[Noxx]

Yes absolutely.

 

[donnybrook]

Thanks Noxx. Just seem to be producing a great deal of powder after filtering and drying. I found it easier to smelt gold powder with just borax after cleaning.

Donnybrook

 

[goldsilverpro]

If you want it pure (99.95%, or better), re-dissolve it and re-drop it. If you don't care about purity, melt it. The best way is usually not the easiest way.

 

[Harold_V]

Thanks Noxx. Just seem to be producing a great deal of powder after filtering and drying. I found it easier to smelt gold powder with just borax after cleaning.

Donnybrook

One does not smelt gold powder---one melts gold powder. Smelting is the process of recovering values from ores.

That being said, melting with borax will not appreciably improve the quality of recovered gold. If that were not the case, all that would be necessary to improve quality would be to melt gold.

If you use borax when melting, traces of clean metals that may be present will be included in the gold. Oxides will be removed. You can see evidence of that by looking at a molten button of gold. If you sprinkle borax on the surface, the oxides will be absorbed by the borax, which slowly discolors. However, any base metals contained within the gold are constantly exposed to the atmosphere, and oxidize readily. There is a constant supply of oxides that leave the surface of the gold discolored when it solidifies. If you flux the button while still hot, but frozen, you can remove the oxide surface, but the quality of the gold is still compromised. You are far better served to re-process once processed gold, particularly if you use poor procedures and recover from dirty solutions.

Harold

 

[Platdigger]

Donnybrook,
If I may, how are you precipitating the gold from your iodine leach?

 

[donnybrook]

Platdigger,
Thanks for the question and thanks to others for offering their advice. Yes Harold it is melting when reducing fine gold powder to metal or should I say gold sulphides to metal?

I have been using caustic or Lye to bring the leach to pH 7 and the metals drop from that using the late Ken Williams method.

The same with chlorine leaching but iron is always a problem so after tabling I roast and then try and remove as much iron as I can with hydrochloric acid. Filter and rinse in a calico bag. I then run the leach at the suggested pH. The iron and gold seem to be closely associated. I am recovering the sands from an old mine site and its settling dams and the table works well and gives me a suitable concentrate to leach.

I'm yet to redissolve the powders in Ar and then drop again with SMB.

Donnybrook

 

[viktor1984]

so i can re-dissolve the black powder that dropped with smb
with the hcl clorox. correct?
becuase i have few little cups with black powder looking stuff on buttom. and i want to redissovle it and drop it all at same time.
so will it work?
thanks

 

[Barren Realms 007]

so i can re-dissolve the black powder that dropped with smb
with the hcl clorox. correct?
becuase i have few little cups with black powder looking stuff on buttom. and i want to redissovle it and drop it all at same time.
so will it work?
thanks

It should work. Combine the lots and process as on group. The black powder might not be pure gold so go thru your HCL & water wash processes before you disolve your gold.

 

[tonyroland]

Does anyone on this site have experience processing black sand concentrates. I am in North Georgia and have data stating that black sand concentrates from areas near dalonega have heavy 1.5 .oz to 5 oz per ton values. I have tried heating with salt then fracturing by dumping into cold water, re-separating by and then leaching both with Ar and Clorination.
My problem is that black sand contains Iron and when it goes into solution I have been unable to drop the gold or separate the Iron. I have been reading everything I can on this site to help me understand the chemistry. Is the re a specific place on the forum or a specific person who might be willing to help me work thru this process. Tony Roland