Overview
Stage | Production |
Mine Type | Underground |
Commodities |
|
Mining Method |
- Blast Hole Stoping
- Paste backfill
|
Processing |
- Gravity separation
- Flotation
|
Mine Life | 2041 |
Source:
p. 18
PT-FI is a limited liability company organized under the laws of the Republic of Indonesia. Freeport-McMoRan have a 48.76 percent share ownership in PT-FI and the remaining 51.24 percent share ownership is held by PT Indonesia Asahan Aluminium (an Indonesian state-owned enterprise).
Summary:
The Big Gossan mine is a tabular, near vertical ore body with approximate dimensions of 1,200 meters along strike and 800 meters down dip with varying thicknesses from 20 meters to 120 meters.
The sedimentary-rock hosted ore bodies (portions of the DOZ and all of Big Gossan) occur as “magnetite-rich, calcium/magnesian skarn” replacements, whose location and orientation are strongly influenced by major faults and by the chemistry of the carbonate rocks along the margins of the intrusions.
The copper mineralization in these skarn deposits is dominated by chalcopyrite, but higher bornite concentrations are common. Moreover, gold occurs in significant concentrations in all of the district’s ore bodies, though rarely visible to the naked eye. These gold concentrations usually occur as inclusions within the copper sulfide minerals, though, in some deposits, these concentrations can also be strongly associated with pyrite.
Mining Methods
- Blast Hole Stoping
- Paste backfill
Summary:
The Big Gossan ore body lies underground and adjacent to the current mill site. It is a tabular, near vertical ore body with approximate dimensions of 1,200 meters along strike and 800 meters down dip with varying thicknesses from 20 meters to 120 meters. The mine utilizes a blasthole stoping method with delayed paste backfill. Stopes of varying sizes are mined and the ore dropped down passes to a truck haulage level. Trucks are chute loaded and transport the ore to a jaw crusher. The crushed ore is then hoisted vertically via a two-skip production shaft to a level where it is loaded onto a conveyor belt. The belt carries the ore to one of the main underground conveyors where the ore is transferred and conveyed to the surface stockpiles for processing.
The Big Gossan fleet consists of over 88 pieces of mobile equipment, which includes 12 LHD units and 9 haul trucks used in development and production activities.
Processing
- Gravity separation
- Flotation
Source:
Summary:
The mill produces copper and gold concentrate from mined ore through a process to separate valuable minerals from the impurities covering them. The main steps in the process are crushing, grinding, flotation, and dewatering. Crushing and grinding transform ore size into fine sand in order to release particles containing copper and gold.
Flotation is a separation process to produce copper-gold concentrate. Concentrate slurry consisting of finely ground ore and water mixed with reagents is introduced into a series of mixing tanks called flotation cells, where air is pumped into the slurry.
The reagents used are lime, frothers and collectors. Frothers form stable bubbles that float to the surface of the flotation cell as froth. Collectors react with valuable metal sulfide mineral particle surfaces. rendering these surfaces hydrophobic. The hydrophobic sulfide mineral particles adhere to the air bubbles rising from the slurry zone into the froth floating on the surfac ........

Combined production numbers are reported under
Grasberg Complex
Operational Metrics:
Metrics | 2019 | 2018 | 2017 | 2016 | 2014 |
Daily milling rate
| ......  | ......  | ......  | 900 t | 900 t |
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Reserves at December 31, 2019:
Category | OreType | Tonnage | Commodity | Grade | Recoverable Metal |
Proven
|
Mill / Sulphide
|
17 Mt
|
Copper
|
2.55 %
|
|
Proven
|
Mill / Sulphide
|
17 Mt
|
Gold
|
1.03 g/t
|
|
Proven
|
Mill / Sulphide
|
17 Mt
|
Silver
|
15.71 g/t
|
|
Probable
|
Mill / Sulphide
|
38 Mt
|
Copper
|
2.22 %
|
|
Probable
|
Mill / Sulphide
|
38 Mt
|
Gold
|
0.95 g/t
|
|
Probable
|
Mill / Sulphide
|
38 Mt
|
Silver
|
13.26 g/t
|
|
Proven & Probable
|
Mill / Sulphide
|
55 Mt
|
Copper
|
2.33 %
|
2.6 B lbs
|
Proven & Probable
|
Mill / Sulphide
|
55 Mt
|
Gold
|
0.97 g/t
|
1.2 M oz
|
Proven & Probable
|
Mill / Sulphide
|
55 Mt
|
Silver
|
14.04 g/t
|
15.8 M oz
|
Heavy Mobile Equipment as of December 31, 2019:
HME Type | Quantity |
Load-Haul-Dump (LHD)
|
12
|
Truck (haul)
|
9
|
Corporate Filings & Presentations:
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Aerial view:
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