jman
I am back in, fingers crossed. I believed Syama was free milling. Doesn't that mean it is not refractory nor complex to mine?
Cheers
Have just double-checked the Resolute website,
And the Syama ore is definitely refractory. Here is a good definition of "free milling" that I found on e-goldprospecting.com:
"Free milling ores are defined as those from which Cyanidation can extract approximately 95% of the gold when the ore is ground to size 80% < 75 µm, as commonly applied in industrial practice, without incurring prohibitively high reagent consumptions".
In Resolute's case, if they persisted with grinding this ore to a much finer grind to try and expose more of the gold to the cyanide solution, the milling costs would be prohibitive, mill throughput would drastically drop, and the entire operation would rapidly become uneconomic. Hence the introduction of the roasting circuit.
Without being overly knowledgeble regarding metallurgical process flow-sheets, their circuit might look something like this:
A.) Refractory ore passed through a series of crushers ie. primary, secondary etc to reduce bulk grain size.
B.) Sulfide Flotation circuit as a pre-concentration step, to remove as much of the sulfide matrix as possible.
C.) Concentrate passed through a Roasting circuit, ore heated to over 1000 deg Farenheit to drive off remainder of sulfides.
D.) Conventional Carbon-in-Leach step, to absorb gold to activated carbon.
E.) Gold-loaded carbon transferred to vessel where it is chemically stripped and the carbon recycled.
F.) Gold is precipitated from solution by electrolysis, or by the substitution of an appropriate chemical.
Another thing to consider here, other than the reagent costs which will be significant, is that the wet sulfur dioxide scrubbers required for the roasting circuit are very expensive to maintain and replace, and can frequently cost more than the roaster. So yes, this ore could be considered complex to process. For these types of operations, grade is king, and higher grades and/or higher mill throughput are required to offset the higher processing costs.
Still just watching atm though
:
jman