Correction to above post....cyanide leach not arsenic.
I believe aqua regia was used as a leach well before 1887…And I also believe cyanide was used as a leach by certain alchemists before 1887 as well…But who can say for certain… https://www.google.com/search?q=alchemy+images+green+dragon+eating+sun&client=safari&channel=iphone_bm&ei=33IXZLD2C9Lg0PEPxvml6AI&oq=alchemy+images+green+dragon+eating+sun&gs_lcp=ChNtb2JpbGUtZ3dzLXdpei1zZXJwEAMyBQghEKABMgUIIRCgAToKCAAQRxDWBBCwAzoFCAAQkQI6BQgAEIAEOgYIABAWEB46BQgAEIYDOgUIIRCrAjoICCEQFhAeEB1KBAhBGABQvglY-KQBYKu3AWgBcAB4AIABrQGIAcQSkgEEMTcuN5gBAKABAcgBCMABAQ&sclient=mobile-gws-wiz-serp#sbfbu=1&pi=alchemy images green dragon eating sunOkay I'll try to answer your question in a different way.
Leaching is typically used on raw ore - not concentrates. It could work just as well on concentrates but why bother concentrating your ore first? Concentration beyond separating the gangue from the ore is just an extra step. The real challenge in leach mining is finding a leach chemical balance process that is most effective on your ore. That's where the expense, time and resources pay off with leaching.
Leaching started in the "old days" (beginning in 1887) when it was discovered that a cyanide solution could dissolve gold and some other metals from ores that had poor recovery with smelting. The first successful leach operations were on abandoned Nevada mine ore piles from gold and silver mines that had significant recoverable values. Many of the first mines to use this new process in Nevada were booming successes. Free metals from already mined ore is a miners dream.
The dream didn't last long when it was discovered that the mix of metals in some ores prevented the cyanide from doing it's job or the leach was consumed or contaminated by non target metals. Cyanide is easily loaded with low paying copper when you are trying to extract gold. Iron can block the gold from reacting with the cyanide and a whole bunch of other problems can arise that kill the profitability of a leach operation. Depending on the local geochemistry and minerals leaching can be a big boon to miners or it can be an economic bust.
Leaching can improve your recovery over milling and smelting IF your ore has significant loss of values with your current processing methods and IF the ore is susceptible to the leach you choose. Better recovery doesn't add up to more money for the miner unless the cost of recovery is less than the gold values recovered. For this reason alone small batch leaching doesn't make much sense. If you have a small batch (500 tons or less) of concentrate you might try a pre made commercial leach on a portion of it to see if you get good values. That's going to be an expensive and time consuming process because you need to build a leach pad, recovery towers with plumbing and pumps, processing tanks, chemicals and disposal and storage facilities. Leaching is a slow process, it's not like milling where you start seeing results the same day you begin processing.
Every mine using leach recovery today has a different leach. The leach designed for each mining operation has to change as the quality and chemistry of the newly mined ore changes. Leaching is very cost effective on a large scale where you can maintain staffed chemistry and testing labs to control and adjust the leaching and processing systems. Without that customization ability leaching is pretty much a hit and miss proposition even within the same mine.
So give leaching a try if that floats your boat. Without a significant deposit that's susceptible to leach processing it's not economical but life isn't all about profit in my view. The knowledge you gain working with leaches might pay off in other ways that can't be counted in dollars and cents.
Heavy Pans
I owe it to my buddy Mitch to see this mining thing through to the end, even if I fail it's an adventure and I can honestly say I tried, besides I didn't collect all this equipment just so I could talk about it.Okay I'll try to answer your question in a different way.
Leaching is typically used on raw ore - not concentrates. It could work just as well on concentrates but why bother concentrating your ore first? Concentration beyond separating the gangue from the ore is just an extra step. The real challenge in leach mining is finding a leach chemical balance process that is most effective on your ore. That's where the expense, time and resources pay off with leaching.
Leaching started in the "old days" (beginning in 1887) when it was discovered that a cyanide solution could dissolve gold and some other metals from ores that had poor recovery with smelting. The first successful leach operations were on abandoned Nevada mine ore piles from gold and silver mines that had significant recoverable values. Many of the first mines to use this new process in Nevada were booming successes. Free metals from already mined ore is a miners dream.
The dream didn't last long when it was discovered that the mix of metals in some ores prevented the cyanide from doing it's job or the leach was consumed or contaminated by non target metals. Cyanide is easily loaded with low paying copper when you are trying to extract gold. Iron can block the gold from reacting with the cyanide and a whole bunch of other problems can arise that kill the profitability of a leach operation. Depending on the local geochemistry and minerals leaching can be a big boon to miners or it can be an economic bust.
Leaching can improve your recovery over milling and smelting IF your ore has significant loss of values with your current processing methods and IF the ore is susceptible to the leach you choose. Better recovery doesn't add up to more money for the miner unless the cost of recovery is less than the gold values recovered. For this reason alone small batch leaching doesn't make much sense. If you have a small batch (500 tons or less) of concentrate you might try a pre made commercial leach on a portion of it to see if you get good values. That's going to be an expensive and time consuming process because you need to build a leach pad, recovery towers with plumbing and pumps, processing tanks, chemicals and disposal and storage facilities. Leaching is a slow process, it's not like milling where you start seeing results the same day you begin processing.
Every mine using leach recovery today has a different leach. The leach designed for each mining operation has to change as the quality and chemistry of the newly mined ore changes. Leaching is very cost effective on a large scale where you can maintain staffed chemistry and testing labs to control and adjust the leaching and processing systems. Without that customization ability leaching is pretty much a hit and miss proposition even within the same mine.
So give leaching a try if that floats your boat. Without a significant deposit that's susceptible to leach processing it's not economical but life isn't all about profit in my view. The knowledge you gain working with leaches might pay off in other ways that can't be counted in dollars and cents.
Heavy Pans
