blacktoad said:
I have found lots or chemicals listed under urea. Witch chemical formula is used in AR to drop out the gold? Oh by the way. when one has the brownish particles of gold can they go directly to melt or does one have to go through the trouble to make them gold looking (cleaning Gold Process)
I can't help you with the urea question, but I sure have an opinion on the precipitated gold.
Do not expect precipitated gold to appear as if it's been melted. Regardless of how clean it may be, it will have a dull appearance, and will range in color anywhere from a very pale light tan/orange color through as dark as blackish brown. Gold that has been precipitated from clean, concentrated solutions, using SO2 as a precipitant, resembles ground cinnamon. Color is an indicator of cleanliness in many cases, but it won't be shiny even under the best of conditions because the surfaces are small and reflect light in all directions. As a result, it isn't shiny. You'll notice that if it's clean enough, all it takes to make some of it shine is to abrade it with almost anything---the abrasion tends to flatten the particles and align them such that they form a uniform surface, which becomes the familiar color of gold, and reflects light in a given direction.
If your objective is clean gold, only a complete fool would melt the powder without washing. Regardless of how clean the solution from which it came may be, unless it was totally free of contamination, the precipitated gold will contain some of the contamination, from drag down, if from no other means. It becomes perfectly obvious why gold should be washed when you do so. What you remove from the gold will be evident in the HCl and water that is used. If it's not removed, it will report in the melted gold, especially if you melt with soda ash, which will reduce the contaminants to the elemental state, and combine them with the gold. It may appear to be clean because you don't see any signs of oxides, but if it's melted without flux, it will readily oxidize, leaving the gold discolored.
Unless your objective is to recover gold with no regard to quality, you should not skip the washing process. If your objective is high quality gold, you'll slowly come to realize that you can't achiever your goal by a single chemical refining, even with careful washing procedures.
One of the best tests for your gold quality is how it melts without flux. High quality gold will do so without forming any oxides on the surface. If, when you melt the powder, it won't agglomerate readily and form a puddle that is shiny, it isn't very clean.
Fine gold will melt in a dish that is coated with enough borax to lubricate the gold and allow it to flow well. When the gold is fluid, it will be a luminescent green/yellow color, and will remain bright upon solidification. It should also pull a deep pipe in the center, as the last bit solidifies. When you have finished melting gold, the dish should still be clean looking, with a slight purple cast to the flux. If the flux is discolored, green, black, or blue, your gold was dirty. If your gold fails to do any of the above, it isn't very pure. If it has a frosted surface, it isn't pure.
Harold
