Small amounts of uranium were also produced by underground in-situ leaching and heap leaching of low grade ore and even waste rock.
12.
Based on an average of $ 27 / ton of low grade ore, that left a freight cost of $ 3 / ton.
13.
Between 1922 and 1995 low grade ore was concentrated on site and the tailings ( ore-washing residue ) dumped in the river also.
14.
In 1983, the price of copper along with the low grade ore being mined led to Kennecott closing the smelter and demolishing it.
15.
Low grade ore needed to be worked on a larger scale to be consistently profitable over a long period, and cheap milling was essential.
16.
Though slower than conventional methods, the microorganisms ( which can also include fungi ) enable the exploitation of extremely low grade ores with minimum expense.
17.
In the chapter above from the Gold Hill Daily News, it states that low grade ore is valued at $ 26 $ 28.00 to the ton.
18.
The railroad now affords for the first time a chance to work this low grade ore profitably . "-Gold Hill Daily News, The first Ore Shipment-Nov 19, 1869.
19.
However, his presidential campaign was ultimately unsuccessful; this can be partially attributed to the discovery of the cyanide process by which gold could be extracted from low grade ore.
20.
In the late 1980s, MIM built an SX EW plant at Mount Isa to recover copper leached from low grade ore stockpiled while mining its Black Rock open cut in the 1960s.
