Environmentally friendly gold extraction from ore.

Mesquite

I ain't no tree-hugger, but ... I'm all in favor of keeping cyanide out of the loop. Better living through chemistry!

Thiosulfate extraction; increased yields.

ricko

Hmmmm.... now, will this drive the value of gold down? Cheers, RickO

guitarwes

If it reduces costs and lets them produce more, I say they will be like the diamond producers/holders and piece it out as to not affect the spot price.

The process sounds interesting, especially since it may open up some production in Australia.

LindeDad

Note that there is no mention of what they do with the waste product or it's long term toxic property's?

Mesquite

"Sodium thiosulfate is a component of an alternative to cyanide for extraction of gold. However, it forms a strong soluble complex with gold(I) ions, [Au(S2O3)2]3−. The advantage of this approach is that thiosulfate is essentially not toxic and that ore types that are refractory to gold cyanidation (e.g. carbonaceous or Carlin-type ores) can be leached by thiosulfate. Some problems with this alternative process include the high consumption of thiosulfate, and the lack of a suitable recovery technique, since [Au(S2O3)2]3− does not adsorb to activated carbon, which is the standard technique used in gold cyanidation to separate the gold complex from the ore slurry."

The MSDS for thiosulfate indicates no environmental hazard. There is no reported LD50/30. They actually use an intravenous solution of thiosulfate as a treatment for cyanide poisoning in people. I guess the thiosulfate process described in the paper solved the [Au(S2O3)2]3− recovery problem. Maybe they use an oxidation step somewhere along the line to convert gold(I) to gold(III)?

Mesquite

duplicate

element159

Thiosulfate also complexes and dissolves silver, which is why it is used as photographic fixer. My understanding is that it is quite low on the toxic scale. Far improved over the more usual techniques involving cyanide or mercury. Normally, gold mining is a particularly nasty business because of those very toxic materials.

BAJJERFAN

Sodium thiosulfate is the stuff you add to aquarium water to kill residual chlorine BEFORE you add fish.