Cyanide and sodium thiosulfate reaction

[kjavanb123]

Hi everyone,

I have been dealing with dry river soil, and most places my aqua regia testing shows strong positive for gold. I follow that test with smelting a sample 10kg with lead oxide then cupel to get the silver gold bead.
Once the sample passed those tests, I collect 100kg sample, sieve it, and prepare a hot cyanide solution, add the soil, mix and in small increments add hydrogen peroxide, for 40 minutes. I then filter the solid, and this is what I am confused. I used zinc powder to drop the values from the cyanide solution, but for the rive soil samples. no zinc powder works.

I read by adding excessive amount of sodium thiosulfate to cyanide solution, it will drop the values as well as destroying cyanide, but in practice it doesn't work. Is this true that sodium thiosulfate destroys the cyanide but drops the gold?

Thanks
KJ

 

[Naughtius Maximus]

Hi everyone,

I have been dealing with dry river soil, and most places my aqua regia testing shows strong positive for gold. I follow that test with smelting a sample 10kg with lead oxide then cupel to get the silver gold bead.
Once the sample passed those tests, I collect 100kg sample, sieve it, and prepare a hot cyanide solution, add the soil, mix and in small increments add hydrogen peroxide, for 40 minutes. I then filter the solid, and this is what I am confused. I used zinc powder to drop the values from the cyanide solution, but for the rive soil samples. no zinc powder works.

I read by adding excessive amount of sodium thiosulfate to cyanide solution, it will drop the values as well as destroying cyanide, but in practice it doesn't work. Is this true that sodium thiosulfate destroys the cyanide but drops the gold?

Thanks
KJ

I believe you have to drop the pH to precipitate with zinc but that will also release cyanide. I would make sure you have excellent ventilation.

 

[Yggdrasil]

Hi everyone,

I have been dealing with dry river soil, and most places my aqua regia testing shows strong positive for gold. I follow that test with smelting a sample 10kg with lead oxide then cupel to get the silver gold bead.
Once the sample passed those tests, I collect 100kg sample, sieve it, and prepare a hot cyanide solution, add the soil, mix and in small increments add hydrogen peroxide, for 40 minutes. I then filter the solid, and this is what I am confused. I used zinc powder to drop the values from the cyanide solution, but for the rive soil samples. no zinc powder works.

I read by adding excessive amount of sodium thiosulfate to cyanide solution, it will drop the values as well as destroying cyanide, but in practice it doesn't work. Is this true that sodium thiosulfate destroys the cyanide but drops the gold?

Thanks
KJ

A slight excess of Cyanide is helpful.
And if there is little Gold you may not even see it dropping.
Test with a strip of Aluminum foil first maybe.

 

[kjavanb123]

Hi

Thanks for your reply. I used the Hokes method to test for gold in cyanide solution, I siphoned 2.5ml of pregnant cyanide solution, under fume hood, added 2.5 ml of HCL, the color changed to yellow, then using a Q tip, I collected the solution, and added stannous chloride testing solution, after 30 minutes it turned to light blue color, which is different from the purple I am used for gold.

 

[Yggdrasil]

Hi

Thanks for your reply. I used the Hokes method to test for gold in cyanide solution, I siphoned 2.5ml of pregnant cyanide solution, under fume hood, added 2.5 ml of HCL, the color changed to yellow, then using a Q tip, I collected the solution, and added stannous chloride testing solution, after 30 minutes it turned to light blue color, which is different from the purple I am used for gold.

Did you test using an Aluminum strip/foil in the Cyanide solution?

 

[kjavanb123]

Did you test using an Aluminum strip/foil in the Cyanide solution?

Hi

Yes I used zinc powder to cement the gold, but it only dropped black powder which didn't dissolve in HCL but dissolved in nitric and solution turned pale yellow, negative for silver or palladium.

 

[Naughtius Maximus]

Has anyone tried putting the solution directly into an Atomic Absorption spec?

 

[kumbirai.mhere]

Did you test using an Aluminum strip/foil in the Cyanide solution?

How do you test gold in cyanide solution using aluminium foil?

 

[anachronism]

Has anyone tried putting the solution directly into an Atomic Absorption spec?

Yes. Properly diluted to the range within which the AAS reads, it works perfectly.

 

[Yggdrasil]

How do you test gold in cyanide solution using aluminium foil?

Just dip it in for a few seconds and see if it picks up a darker color.
It will tell if there are metals dissolved in the Cyanide solution.

 

[anachronism]

How do you test gold in cyanide solution using aluminium foil?

The foil turns brown/black when gold is present and if there is a lot of gold it ultimately precipitates the gold and dissolves into the solution.

 

[kumbirai.mhere]

On the same subject of gold cyanidation I have read that lead nitrate accelerates gold leaching. Is it true or it only applies to sulphide ores?