Yanacocha is the largest gold mine in South America, Yanacocha gold mine located in the province and the department of Cajamarca, Some 45km from Cajamarca in northern Peru, at an altitude of 4,700m, The sheer scale of the Yanacocha gold mine in Cajamarca, Peru, is staggering. It is the largest gold mine in Latin America, and the second largest in the world, covering 535 square miles.
Minera Yanacocha operates a complex of five gold mines and two processing facilities with development activities in four primary basins. Not only was this the first significant foreign investment in Peruvian mining for 20 years, but the project was undertaken in an area where guerillas were active, so the operation had to be heavily protected without antagonising local residents. The operation is a joint venture between Newmont (51.35%), Minas Buenaventura (43.65%) and the International Finance Corporation (5%)
The Yanacocha gold district is a 10x4km zone of altered rocks within a belt of tertiary volcanics that extends the whole length of Peru.
In the Yanacocha district, the volcanic pile has been subdivided into three groups:
In the Yanacocha district, the volcanic pile has been subdivided into three groups:
1.) The lower andesite sequence, consisting of an intercalated sequence of block and ash flow tuffs, flow sequences with rare, associated flow domes, and an upper zone dominated by ignimbrites and fine-grained, laminated epiclastic sequences that show a transition into the overlying Yanacocha pyroclastic sequence
2.) The Yanacocha pyroclastic sequence, a variable sequence of lithic to lithic crystal tuffs, extensively altered in the central portion of the district and primary host to the majority of gold deposits within the district;
3.) The upper andesite-dacite sequence, consisting of intercalated units of andesite to dacite flows, dominated by multiple flow dome complexes in its upper portion.
Ar-Ar age dating within the district has yielded ages ranging from 19 Ma (basal lower andesite) to >12 Ma (upper andesite sequence). The entire volcanic pile has been crosscut by multiple phases of phreatic (vapor phase dominant), phreatomagmatic (intrusive component) and hydrothermal breccias, and intruded by multiple late-stage phases of andesite dikes and dacite to quartz dacite plugs, dikes and stocks (10–8 Ma), the latter of which are associated with shallow Au-Cu porphyry-style mineralization that underlies the high-sulfidation epithermal deposits.
Andesitic domes and dome complexes have been silicified and leached by epithermal gold-bearing solutions in at least nine distinct deposits. The mineralised sequences, which can also contain significant amounts of silver, are flanked by extensive argillitic alteration, and subsequent events have created siliceous breccia pipes with localised high gold grades
3.) The upper andesite-dacite sequence, consisting of intercalated units of andesite to dacite flows, dominated by multiple flow dome complexes in its upper portion.
Ar-Ar age dating within the district has yielded ages ranging from 19 Ma (basal lower andesite) to >12 Ma (upper andesite sequence). The entire volcanic pile has been crosscut by multiple phases of phreatic (vapor phase dominant), phreatomagmatic (intrusive component) and hydrothermal breccias, and intruded by multiple late-stage phases of andesite dikes and dacite to quartz dacite plugs, dikes and stocks (10–8 Ma), the latter of which are associated with shallow Au-Cu porphyry-style mineralization that underlies the high-sulfidation epithermal deposits.
Andesitic domes and dome complexes have been silicified and leached by epithermal gold-bearing solutions in at least nine distinct deposits. The mineralised sequences, which can also contain significant amounts of silver, are flanked by extensive argillitic alteration, and subsequent events have created siliceous breccia pipes with localised high gold grades
Process Of Gold Mining In Yanacocha Gold Mine Peru
The process of gold from mining the
first is drilling using Ingersoll-Rand DM45E and Atlas Copco machines
and blasting are the responsibility of Minera Yanacocha. elimination of
materials containing gold and silver began with drilling the ground to
make a hole that will then condition with explosives..
 |
 |
The explosions carried out and the subsequent removal of ground begin to form large holes in the ground called pits. Stone materials have been destroyed and then transported by haul trucks ( which can load up to 250 tons of mineral rock) The ore is transported 2.5km or more to the leach pads using wheeled loaders and 85t-capacity trucks, and is heaped by stackers
Ground Preparation and pad construction: Here the soil on a slightly
sloping ground is compacted and covered by an impermeable pad (can be
made of plastic).
Ore stacking: Then the crushed ore is stacked in the form of big
heaps. Amount of fines is decreases as low as possible to improve
permeability.
Then the leaching agent such as cyanide or acid is sprayed over the
heap.
As, the reagent passes through the heap; the valuable metals get
dissolved in it.
The solution containing metal is drained from the heap and collected
in a pond and the solution is sent for subsequent process for metal
recovery to the processing plant.
With gold mineral processing plant ball mill trying to process the metal
that can not be obtained by heap leaching. Gold recovered within 24
hours, unlike the heap leach process lasted almost 60 days. Construction
began in mid-2006 and concluded in early 2008, with an investment of
270 million dollars and the production plan for 9 years. 1500 workers
participated in the construction of this important project which has a
processing capacity of 5,000,000 tons / year.
Carbon In Columns comprise the cyanide leach solution, and agitated in
the leach tanks, and agitated with the ore while the gold is being
dissolved. This assures a rapid interface between the carbon and the
gold loaded cyanide solution. Granular, hard carbon is used, in the
size range of 10-16 mesh. The carbon is then removed by screening,
across a carbon screen, allowing the liquid and finely ground ore (-100
mesh) to pass through easily, and retaining the carbon on the screen.
The pregnant cyanide solution flows through the carbon columns, which
are generally situated in step fashion, so that the overflow from the
highest column will gravity flow to the next column, alleviating the
requirement for pumping. The gold adsorbs onto the surface of the
carbon. The loaded carbon is periodically removed from the columns, and
sent to the stripping circuit.
The gold obtained in the Merrill Crowe process is subjected to operations of drying kiln retort at 650 ° C. Finally, the obtained product undergoes a process of smelting electric arc furnace to 1,200º C for the Dore, a bar made of a mixture of gold and silver. After recovery, the contained metal is smelted and cast as 400oz doré bars containing 75% gold and 20% silver. The UK-based refiner Johnson Matthey is responsible for shipping the bars.
The gold obtained in the Merrill Crowe process is subjected to operations of drying kiln retort at 650 ° C. Finally, the obtained product undergoes a process of smelting electric arc furnace to 1,200º C for the Dore, a bar made of a mixture of gold and silver. After recovery, the contained metal is smelted and cast as 400oz doré bars containing 75% gold and 20% silver. The UK-based refiner Johnson Matthey is responsible for shipping the bars.
/*