Opal2000 said:
Looking for advice on the best method for separating PMG's from raw ore in the correct sequence to recover the 4 main metals concentrated in the ore.
The ore is concentrated mainly - Pd 68.9%, Ir 8.1%, Ag 6.9%, Au 5.7 % .
Would a simple mixture of Hydrochloric acid and Hydrogen peroxide ( 20:3 ) dissolve just the Palladium from the ore or will it dissolve all? or is there a better way?
My knowledge on refining is very limited. Any advice would be great.
Is this really an ore concentrate? To me it feels very strange to not see any platinum. Most Australian PGM ores have palladium to platinum concentrations of 2:1.5. Only one deposit mentioned any relevant levels of iridium.
http://www.australianminesatlas.gov.au/aimr/commodity/platinum_group_elements.html
If this is an ore then the chemical form of minerals present could create some problems, for example silver chloride, silver sulfide or gold telluride could make it harder to process. Roasting might be required as a first step but beware of the gases as they could be lethal, especially if there is any arsenic in the concentrate. Even silver chloride is volatile and poisonous when roasted. Proper ventilation and dust filters are needed to do it safely and to catch any values literary going up in smoke.
The physical form would also affect the process, does the concentrate come as fine particles or as nuggets? If it is a fine particle concentrate then it could probably be leached quite simple in acid as it is while larger nuggets might need hours or days of boiling acid to dissolve properly.
With the above composition and values, the silver is more of a nuisance, no concern should be taken to the recovery of silver as the value of it is minimal compared to any of the other metals. If it could be recovered after the other metals are collected then it's okay and an added bonus, but it should not be of primary concern.
Just as 4metals suggest, I would advice on making a number of tests on smaller samples to see what dissolves. And as we say here on the forum, you never lose your precious metals unless you throw it away. A proper stockpot, saving any filters and testing along the way to follow your precious metals will help you keep any precious metals that comes through your door.
Finally, if you are not an expert on refining, maybe this is something best handled by an outside expert. PGM refining isn't the easiest thing to do.
Göran