Tin Chloride in gold sulphides

[donnybrook]

Wondering whether some one could advise me. I have been working on some gold sulphides and intended to use the Chlorine Leaching System. After roasting I then gave it a weak acid bath to clean out iron etc and it came up purple. I live in Australia and this particular ore comes from a remote area a long way from me. It looks as though they were hand picking the ore. There is no water around and I thought they were carting the best off somewhere else to treat it.

After I let the first acid wash sit the purple dropped out of it over night. I suspect that it precipitated some other base metal. Has anyone had this experience? If the tin has precipitated a base metal will it interfere with the chlorine leach? I thought I would also try the iodine leach. This leach does not worry about iron if kept at pH 4.5.

 

[Geo]

where did the tin chloride come from? are you suspecting tin in the ore?

pull the purple powder out and incinerate it.put it through a hot hcl bath and follow with a couple of water rinses. dissolve whats left and test with stannous chloride.

 

[donnybrook]

Thanks Geo. An unusual ore. Also a visible gold in it with sulphides. Just doing small assays . When I have made stannous chloride by boiling in hydrochloric its the same colour. I used pool chlorine on the sample and adjusted with hydrochloric to 8.5 and that is what has happened. Perhaps the stannous chloride is all it is and can be safely decantered filtered out. I have seen the same thing happen when working with AR and jewellery containing tin. I'll recover the stannous chloride by filtering to see if there are any solids. This might be why the old diggers walked off and left it. Perhaps too complicated. In the past I have boiled down AR with gold in it and did not know there was zinc in the material. It hit a certain pH and the whole lot bottomed in the dish.

Thanks donny

 

[donnybrook]

Geo, Sorry it will only go purple ( Purple of Cassius) if it comes into contact with gold??? There must also be a gold chloride within the ore??? Not sure? Perhaps the leach undertook a dissolution to form or create a gold chloride. That could be where the gold is viz combined with the tin as a precipitant. Trying to work out a recovery process. I do have a Wilfley Table which I will use if viable. Perplexed to say the least.
donny

 

[Geo]

silver will form a purple colloid too but not by the same mechanism.as far as colloids of gold, they can go across the largest portion of the spectrum. (blue,purple,red to violet) usually we attribute a purple colloid as being gold.

 

[Geo]

the tin can be removed by milling,incineration and dissolution in hcl. roasting the ore should be done anyway to remove sulfides. the most important thing to do is to ensure gold content and then quantity to make sure its worth the effort.

 

[donnybrook]

Thanks Geo, I wll get back to you and let you know how we go.
Kindest Regards,
Don Buckley