ashir wrote: ↑
February 17th, 2019, 8:36 pm
thanks kj. yes rotarg furnance is difficult to prepare at home, but once i will try. and after smeltinv with silver, there is no need of any cupelation! or 2 step smelting is required?
What I do here is to use lead oxide as collector, smelt everything, skim off slag, then oxdize the lead into lead oxide and all of the base metals presented in lead will be skimmed off.
Near the end silver is added and remaining lead is oxidized and skimmed off till only silver is left.
You can either run your silver dore in a silver parting cell, if I recall kadriver has a great threat about silver cell using stainless steel bowl.
Then collect the slimes, dissolve in HCL, the AR to dissolve gold.
You can scorify the silver dore, add volume wise 1:1:1 soda ash, borax and glass to molten silver to remove the base metals, you need a steel pipe connected to an air compressor to slowly blow air into molten silver this oxdizes base metals and they form a darker donut shaped layer on top of molten silver, just add that flux and pour, repat till bubbling air in silver doesn't produce any dark layer.
At this stage molten silver looks like mirror, this is silver without any tin or copper, you can dissolve in nitric, collect the residue and dissolve in AR.
You dissolve your silver dore in warm nitric acid, this results in silver/copper nitrate solution and gold with tin nitrate (metastanat acid) form at the bottom of your beaker.
Decant the solution, wash the gray residue with hot water let it settle decant do this 3 times, add lye to gray residue it reacts solution turns black add water decant, you should see your gold powder at the bottom.
Silver/copper nitrate solution, you add salt till the silver chloride is fomed, filter it and keep adding hot water till the solution coming out of filter is clear and no more blue.
And again do this on a small scale test to get the feeling.
Best of luck