# hoelp on recovery of gold from calvarite



## giom (Apr 18, 2018)

hello whats the elterntive method biside cynide for calvarite and silvanite gold ore .any body can help me for that answer thanks alot


----------



## g_axelsson (Apr 18, 2018)

I know that Boliden have developed a proprietary method that they will license for gold tellurides.
I have no idea what it is but the end result is a telluride concentrate as well as a higher extraction rate of the gold compared to other methods.

Göran


----------



## giom (Apr 18, 2018)

thanks mr goran .iwas working on this ore for some time .and its not that simple to refine .iwill keep trying thanks sir


----------



## Deano (Apr 18, 2018)

Both sylvanite and calaverite can be dismantled by leaching with 12% nitric acid overnight at room temperature.

Occasionally there will be impurities present which will require a longer leach time, I usually give it 24 to 48 hours being sure that minimal evaporation takes place.

The gold will be suspended in the leach solution virtually as atoms and will pass straight through a filter paper.

If you add an equal amount of 1:4 aqua regia to the beaker as to the volume of the original leach you will dissolve the gold almost instantly.

You now simmer the beaker of liquid until the fumes evolved change from orange/brown to white.

Give it another 5 minutes on the hot plate to drive off any residual nitric fumes.

Take it off the hot plate and let it cool down in the fume cupboard before filtering.

Your gold is now present in the filtrate as gold chloride, it will respond to all the standard analytical methods such as AAS etc.

Deano


----------



## giom (Apr 21, 2018)

thanks mr deano 
i have tryed .washnig with nitric befor dry the powder its remain as light brown powder and then aqua regia .after desolving all brown powder went into solution the rest is grey silvery powder wont desolve at all in aqua regia i asume is electrum i can see gray silvery metal .the brown pwoder that desolve in aqua regia whene i precipate with smb its orange brown powder .. the color of the ore before any desolution its brasse yellow to light yellow powder ..after aqua regia its gray that dont desolve in aqua regia .thanks mr deano


----------



## eaglewings35 (Aug 23, 2018)

Deano said:


> Both sylvanite and calaverite can be dismantled by leaching with 12% nitric acid overnight at room temperature.
> 
> Occasionally there will be impurities present which will require a longer leach time, I usually give it 24 to 48 hours being sure that minimal evaporation takes place.
> 
> ...


Deano, will this also drag down any copper, silver, or other metals? How can you make it drop gold only?


----------



## Deano (Aug 23, 2018)

If you have any metals apart from gold in solution you will get co-precipitation of these metals no matter which precipitant you use.

All that you are looking at is what level of base metal contamination comes from your particular combination of base metals and precipitant.

Doing your precipitation at true pH 2.5 will give you a cleaner drop, note the use of the word "cleaner".

If you could use a special precipitant to get just pure gold then people would not have to go to great lengths to get really high purity gold.

The simplest approach is to decide what purity you will accept and to clean up your gold to that purity.

I use a technique of simmering the gold in HCl until the gold clumps and then filtering the gold from the liquor. This will, no matter how dirty the gold is, get you at worst 999 gold, usually 9999 gold.

Always note that the base metals dissolved from the gold in the above method will dissolve some of the gold you are trying to clean.

If you re-drop this gold you will get a fairly clean drop, I usually take this gold and add it into the next large batch I am putting through in order to save cleaning up multiple small batches.

Deano


----------



## fishaholic5 (Sep 4, 2018)

Deano said:


> Both sylvanite and calaverite can be dismantled by leaching with 12% nitric acid overnight at room temperature.
> 
> Occasionally there will be impurities present which will require a longer leach time, I usually give it 24 to 48 hours being sure that minimal evaporation takes place.
> 
> ...



Deano, does this apply to other Telluride's and to what extent does AR itself attack Precious metal Telluride compounds?

Cheers Wal


----------



## Deano (Sep 4, 2018)

Petzite, Muthmannite, Nagyagite, Montbrayite, Sylvanite, Calaverite and Krennerite will all be dismantled with a 12 - 15% nitric leach.

This is the only way to attack these minerals in a wet chemistry assay method.

For practical purposes all Telluride complexes of gold are insoluble in aqua regia.

Some complexes will surrender very low partial values in aqua regia but it appears that this is more a surface dissolution effect than a quantitative dissolution.

Some of the above complexes can be leached with other solvents but precise identification of the mineral is required to know which method should be used.

Nitric acid is the only universal dismantling method for Telluride gold complexes.


Deano


----------



## fishaholic5 (Sep 5, 2018)

Thanks.


----------



## giom (Sep 13, 2018)

roesting with air or oxegen first is very imprtant part befor any leach .the tellurium has to evaporate preir any thing .it will cause big probleme if it left in ore


----------

