Kinross first acquired an ownership interest in the Paracatu mine upon completion of the merger with TVX on January 31, 2003. On December 31, 2004, Kinross purchased the remaining 51% from Rio Tinto.
Access to the mine is provided by paved federal highways and charter aircraft. The mine is the largest employer in Paracatu, which is predominantly an agricultural town. Gold mining in the Paracatu area dates back to 1722 with the discovery of placer gold in the creeks and rivers of the Paracatu region.
Both the mill and mine operate 24 hours a day, 7 days per week. The nominal plant throughput is 4.8 million tonnes per month or 58 million tonnes per year, considering the present ore hardness.
In 2006, Kinross began an expansion of the mill facilities, which is expected o triple throughput to 61 million tonnes per annum. Production of gold from the expansion plant began in September 2008. The expansion is expected to extend the life of the mining operation to 2040.
The Paracatu mine in Brazil is a large scale open pit operation located near the city of Paracatu, and approximately 230 kilometres from Brasília, the capital of Brazil.
Mineralization at Paracatu occurs within the Morro do Ouro sequence, a series of phyllites that have been thrust from SW to NE producing extensive deformation. Anamalous gold and sulphide mineralization is localized within a 120 ? 140 meter thick high strain zone that dips gently (20°) to the SW and is traceable for over 6 km along a NE-SW trend, and more than 3 km in width. Grade variation can be visually identified within the high strain zone based on readily observable geologic features, the most important of which are the frequency of boudins, intensity of shearing and arsenopyrite content.
Holcombe, Coughlin and Associates (Holcombe 2005), an independent structural geology company, concluded that the timing of gold and sulphide mineralization was syn-deformational. Gold and sulphides are scavenged from the Morro do Ouro sedimentary sequence during deformation and localized within the high strain zone(s) that acted as chemical traps due to dissolution of silica and carbonate and resulting increase in graphite.
Subsequent surface weathering produced four, distinct, weathering horizons. The individual weathering horizons, known as the C, T, B1 and B2 are described in detail in Section 6.0 of this report. Mining to date has exhausted the majority of the softer C and T horizons. The remaining reserves for the project are hosted in the B1 and B2 horizons with the majority (90%) hosted in the B2 horizon. Ore hardness, based on Bond Work Index (BWI) tests on the core samples, generally increases with depth. Table 1-3 presents the average range of BWI measurements by horizon.
Mineralization is confined to the finely laminated phyllites of the Morro do Ouro sequence immediately overlying the massive Serra da Landim metasiltstone member that forms the base of the Paracatu formation. Gold and sulphide mineralization is believed to be syngenetic with the deposition of the phyllites.
In late Proterozoic times, the weaker phyllites responded more easily to tectonic pressures than the enveloping siltstone units. Regional east-west deformation and a later phase of north-south buckling (interpreted to be responsible for formation of a high strain zone, occurred simultaneously with remobilization of gold and sulphide mineralization.
The Paracatu phyllites have been metamorphically altered to lower greenschist facies resulting in pervasive quartz-sericite alteration. Metamorphic grade increases from east to west.
Sulphide mineralization is dominantly arsenopyrite and pyrite with pyrrhotite and lesser amounts of chalcopyrite, sphalerite and galena.
Gold is closely associated with arsenopyrite and pyrite and occurs predominantly as fine-grained free gold along the arsenopyrite and pyrite grain boundaries or in fractures in the individual arsenopyrite and pyrite grains. Thin section analyses indicate 92% of the gold is free. Gold grains typically average 50-150 microns in size. The size and amount of the gold grains does not correlate well with the size or amount of the arsenopyrite grains. It is however essential that arsenopyrite be available as a substrate on which gold can occur.
Mining & Operation
The current mine includes an open pit mine, process plan, tailings dam area and related surface infrastructure. Historically, mining at Paracatu did not require blasting of the ore. Ore is ripped, pushed and loaded into haul trucks for transport to the crusher. In 2004, due to increasing ore hardness in certain areas of the mine, RPM began blasting the harder ore in advance of ripping. Currently, powder factors are very low. The open pit benching operation measures approximately four kilometres by two kilometres, and it is located on a gently sloping hillside. The elevation of the open pit and industrial plant area ranges from approximately 700 to 820 metres.
Approximately 18 million tones movement of ore per year, around 2100 ton per hour; Average grade around 0,433 g/t; No waste stripping is required, nor is drilling employed in the mine; The cut of the oxidated ore (B1) is made through the screeming for tractors (D10 R/T) favoring its shipment through loaders (992 D/G). The dismounting for explosive is used in 20% of the sulphited gold (B2) of bigger hardness
The primary crusher is located within the open pit and is scheduled to operate for 18 hours per day. Run-of-mine ore is delivered by 240 tonne capacity, rear-dump, haulage trucks to the 480 tonne capacity crusher dump hopper. The crushed ore stockpile is a rectangular "A" frame with a dust and rain-cover. Ore is delivered into the stockpile by a tripper conveyor. The grinding circuit is designed to operate at 5,100 t/hr at an availability of 92%. Gravity Separation / Gravity Concentration are six jigs using the radial "Pan-American" design successfully used on the existing plant. The flotation circuit consists of rougher flotation followed by a single stage of cleaning of the rougher concentrate; Carbon-in-leach. Concentrate thickener underflow is pumped to a new trash screen located over the new pre-aeration tank at the CIL plant.
The carbon elution and regeneration plant is designed to handle a carbon batch size of 14 tonnes at 4,500 g Au/t. Electrowinning and Refining.