Fruta del Norte

Overview

Fruta Del Norte gold deposit is located within a 95,000 ha land package in the Cordillera del Condor mountain range of Zamora-Chinchipe province of southeasternEcuador. 

Placer and some bedrock gold have been exploited in the area by artisanal miners and that fact attracted the attention of some Ecuadorian exploration companies. Aurelian Resources Inc purchased the concession in 2002 and the Fruta del Norte gold deposit was discovered in 2006. Kinross acquired the deposit in 2008 by acquiring Aurelian Resources. 

New mining regulations were passed in November 2009, and Kinross operations in Ecuador were permitted to restart. Subsequently, Kinross undertook infill and metallurgical drilling, additional metallurgical testwork, and engineering studies. 

Underground mining methods would be employed for mining the Fruta del Norte deposit. Estimated 6.3 Moz gold and 6.7 Moz silver would be produced over a 16 years mine life.

Average annual production was expected to reach 410,000 oz gold equivalent. 

The initial capital cost for Phase 1 is estimated to be US$ 707 million and the expansion capital cost to implement Phase 2 after an 18 month deferral is estimated to be US$ 413 million. The total sustaining cost over the life of the mine is projected to be US$ 170 million. 

Kinross has prepared a prefeasibility study and 2010 technical report and commenced negotiations with the Ecuadorian government on an exploitation agreement for Fruta del Norte. The company is targeting start up in late 2014.

Location

Ecuador - the Republic of the Equator - is a representative republic located in South America on the shores of the Pacific Ocean. It is bordered by Colombia to the north and Peru on the east and south. It boasts 14.8 million Spanish speaking people.  

Fruta del Norte project lies in the Zamora-Chinchipe province in southeastern Ecuador. The province is located at the heads of the Amazon basin and is characterized by mountainous topography and unique flora and fauna species. Spanish conquistadores clashed with local indigenous people - Shuars, the head hunters that used to shrink the heads of their slain enemies - as early as the 16^th century and that prevented them in settling the gold rich region for centuries to come – e.g. the Zamora city was permanently settled only in 1921. 

Wars with neighboring Peru for the control of the Amazon regions and the mountain range of the Cordillera del Condor meant that the Fruta del Norte region was out of reach for mineral explorers for many decades – until 1999 when the border line was settled through negotiations. 

As a result of its location near the equator and moderate elevation of 1,450 meters above sea level, daily average temperatures are fairly constant at about 16°C.

Annual precipitation in the area is approximately 3,000 mm. Kinross expects that any future mining activity will be conducted year round.

The major Ecuadorian city of Loja is situated about 80 km east–northeast of the Project. The closest community to the deposit is the village of San Antonio. 

Access to the Project is by road, which is paved from Loja to Los Encuentros, and thence gravel to the Project site.

Geology and Mineralization

The Cordillera del Cóndor region consists of sub-Andean deformed and metamorphosed Palaeozoic and Mesozoic sedimentary and Mesozoic arc-related lithologies that formed between the eastern flank of theCordillera Real, and west of the flat-lying strata of the Amazon basin. Intruding the sub-Andean rocks is the Zamora composite I-type batholith, which has associated contemporaneous andesitic volcanism. 

The Fruta del Norte intermediate-sulphidation epithermal deposit is hosted by Misahuallí Formation andesites and feldspar porphyry intrusions. 

The deposit is located within strands of the Las Penas Fault Zone, which is an 80 km north-south regional strike-slip fault. 

Gold and silver mineralized zones typically display intense multiphase quartz–sulphide ± carbonate stockwork veining and brecciation over broad widths (100 - 150 m wide in the coherent central and northern parts of the system where the gold grades are highest). The mineralized envelope extends up to 350 m vertically (and is open at depth) and has a strike length of 1.3 km from north to south. At depth and to the south, the system becomes increasingly silver-rich relative to gold, with silver: gold ratios climbing to 10. Higher silver values are also associated with increases in lead and zinc tenor. 

The bulk of the gold is microscopic and associated with quartz, carbonates, and sulphides. Much of the gold is “free milling” but the mineralization is moderately refractory with approximately 40% of the gold locked in sulphides. Coarse visible gold is common. Gold fineness is typically lower in the northern segment. 

Mineral Reserves of 26.1 Mt at a grade of 8.07 g/t Au and 10.9 g/t Ag were used in the economic evaluation.

Mining & Operation

Underground mining methods would be employed for mining the Fruta del Norte deposit – i.e. traverse open blast-hole stoping with backfill. 

The mine will be accessed via a 1,310 m long north production decline and a 1,580 m long south exploration decline; at the point where the two intersect, a 1,968 m long mine ramp will commence. Level accesses will be driven off the ramp to join with sublevel drifts spaced 25 m vertically. In total, the mine will have 12 sub-levels starting at 1320 Level down to 990 Level. In general, the sub-level drifts and the ramp will be located west of the West Fault, a major geological structure. 

The mine ventilation system will consist of fresh air raises (FAR), return air raises (RAR), both declines and the mine ramp. A dedicated escape-way is centrally located near the level accesses and will contain a ladder-way and landing platforms. The escape-way, and either the north production decline or south exploration decline, serves as the secondary egress route for the mine.

Processing

The capacity of the process plant for Phase 1 was designed at 2,500 t/d through a WOCIL process circuit to support the underground mine plan for non-refractory ore. 

The capacity of the process plant for Phase 2 will be doubled to 5,000 t/d, and the WOPOX circuit will be brought on line at that time to process primarily refractory ore. 

During Phase 1 of ore processing, the process plant will use a combination of conventional milling and carbon-in-leach (CIL) to extract gold and silver from run-of-mine (ROM) ore. The process plant is designed to operate at 2,500 t/d with 90% availability. Annual tonnage treated at design capacity will typically be 912,500 t. The average gold and silver recoveries for Phase 1 are projected at 82.4% and 69.8%, respectively. 

The Phase 1 flow sheet will include a jaw crusher and a semi-autogenous grinding (SAG) mill, ball mill and pebble crusher (SABC) circuit for crushing and grinding. Conventional WOCIL, with a carbon stripping and refining circuit will be used to recover the gold and silver. The leach residue from the WOCIL process will be treated in a SO2/air cyanide destruction circuit. The cyanide destruction product will be thickened and report directly to the tailings storage facility (TSF). A cemented rock-fill plant will be used for mine back-filling during Phase 1 operations.

 In Phase 2 of plant operations, a pressure oxidation (POX) circuit will be introduced to oxidise the sulphide component of the ore and liberate the gold-bearing minerals locked-up in sulphide. The throughput of the plant will also be ramped-up from 2,500 t/d to 5,000 t/d at the onset of Phase 2. In addition to the construction of the WOPOX circuit and its utilities, a second ball mill will need to be added to the grinding circuit in order to accommodate the increased throughput. Hot neutralisation and slurry cooling areas will also need to be added downstream of the WOPOX circuit in order to attain the necessary temperature and pH for WOCIL. A cemented paste tailings backfill plant will be added. Gold and silver recoveries are expected to improve significantly in Phase 2 to 94.4% and 73.8%, respectively. 

The design criteria adopted for the TSF assumes that about 26.1 Mt of processed tailings will be produced over the LOM. Given that approximately 50% of the tailings will be used for underground backfill, the TSF has been designed to store 13 Mt. The TSF will occupy a broad valley located west of the plant site.

Environment & Community

The project must be permitted under separated EISs for mine and processing facilities. 

The proposed mining operations would be constructed on the La Zarza and Colibri concessions.