1. data source
Sources of Data Reference
Greystar documents 1
Greystar advice 2
Testwork report 3
Agreement between Greystar and GRD Minproc 4
GRD Minproc recommendation 5
Calculated data 6
Vendor data 8
To be confirmed TBC
To be advised TBA
The design criteria form the basis for the design of the processing facilities and requiredsite services. Together with the process flow diagrams, the data allows for the definition of the mass balance, preliminary equipment list and some equipments quotation. In addition, it allows for the development of schedules for operating requirements such as power, water and reagents.
The design criteria and the associated mass balances have been used to derive capital cost estimates andschedules for operating requirements such as power, reagents and consumables, etc. Any recovery or similar data presented herein are used for design purposes to size equipment and are not statements of predicted plant performance.
The design criteria have been based on data from various sources and all data is referenced to the sources. It is of particular importance to note areas in whichassumptions have been made and thus require verification.
1.1 CARBON IN COLUMN
Carbon-in-Column circuits are employed to recover gold from heap leach operations. Heap leaching is used as a low capital and operating cost method of recovering gold from low grade surface deposits and waste rock.
Adsorption is a process where a solid is used for removing a soluble substance from the water. In thisprocess active carbon is the solid. Activated carbon is produced specifically so as to achieve a very big internal surface (between 500 - 1500 m2/g). This big internal surface makes active carbon ideal for adsorption.
The pregnant solution resulting from a heap leach is pumped to a series of columns to adsorb the gold and silver containing activated carbon. The contactors consist of a series offive columns that contain a bed of activated carbon. The pregnant liquor is passed up-flow under gravity through each of the columns in series. The solution flow expands and fluidises the carbon bed thus allowing even distribution of the solution through the carbon bed promoting even adsorption onto the carbon.
Item Unit Value Ref
Carbon typePica 210
Upflow velocity m3/h 70
Solution flow, m3/h 350
Required area m2 5.00
Column Diameter (excluding downcomer) m 4,4
Solution Temp ºC 10-20
Bed expansion, % 24-38
Carbon content / m height, t (packed) t 24.4
Nominal packed bed height m 2
Maximum expanded bed height m 2.76
Nominal column height excl. false bottom m 4.76
Number of stages # 6
Interstageelevation difference m 1
Trash screen aperture mm 0.75
Safety screen aperture mm 1
Concentration factor # 3 500
Solution [Au] ppm 0.38
Solution [Ag] ppm 1.89
Carbon [Au] ppm 1,330
Carbon [Ag] ppm 6,615
Total Metal on Carbon ppm 7,945
Solution flow m3/h 3,415
Contained metal g/h 7,752
Carbon flow t/h 0.97
The Guanaco Project has selected the AARL process like elution method. The Elution was initially developed by Ray Davidson at the Anglo American Research Laboratories (AARL) and was refined by various engineers since. Activated carbon that has been loaded with gold and other metals in adsorption processes must be treated by an elution step to desorb the metals from the carbon. This produces asmaller volume of high-grade solution, suitable for final gold recovery by electrowinning and allows the carbon to be recycled to the adsorption circuit.
Elution is usually carried out in a single pressure vessel with a L/D ratio of 6:1 or slightly less in the case of columns 8 or larger.
At the elution plant carbon is transferred from the truck to a sump for transfer to either a storage bin...