quinta-feira, 11 de setembro de 2008

From a Kinross’ public report, 2005 (pages 96-102)

From a Kinross’ public report, 2005 (pages 96-102):



The Paracatu mine site includes an open cut mine, process plant, tailings impoundment area and related surface infrastructure with a throughput rate of 18 million tones per annum (Mtpa). Paracatu (known locally as "Morro do Ouro") is operated by Rio Paracatu Mineracao S.A. ("RPM"), which in 2003 and 2004 was 49% owned by Kinross and 51% owned by a subsidiary of Rio Tinto Plc. ("Rio Tinto"). Kinross acquired its interest in the Paracatu mine in its combination with TVX in January 2003. The mine was operated by Rio Tinto until the end of 2004. On December 31, 2004 Kinross announced that it had completed the purchase of Rio Tinto's 51% interest. Kinross currently owns 100% of the property and is the operator.

Detailed financial, production and operational information for the Paracatu mine is available in the MD&A.


The Paracatu mine is a large scale open pit mine located less than three kilometers north of the city of Paracatu, situated in the northwest part of Minas Gerais State, 230 kilometers from Brasilia, the capital of Brazil, on the paved highway connecting Paracatu (Brasilia) with Belo Horizonte, the state capital of Minas Gerais.

Historically mining at Paracatu did not require blasting of the ore. Ore was 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 kilometers by two kilometers, and it is located on a gently sloping hillside. The elevation of the open pit and industrial plant area ranges from approximately 720 to 820 meters.

In Brazil, mining licenses (claims) are issued by the Departamento Nacional da Producao Mineral (DNPM). Once certain obligations have been satisfied, DNPM issues a mining license that is renewable annually, and has no set expiry date. RPM currently holds title to two mining claims (mining leases) totaling 1,258 hectares. The mine and most of the surface infrastructure, with the exception of the tailings impoundment area, lie within the two mining licenses. The remaining infrastructure is built on lands controlled by RPM under exploration concessions. RPM holds title to 28 exploration concessions in the immediate mine area and has applied for title to an additional 9 exploration concessions in the Paracatu area.

On December 31, 2004, RPM, through exploration permits and mining leases, controlled 8,731 hectares of land. As of December, 2005, RPM had increased its land position to 22,508 hectares. RPM has applications before DNPM to convert four of the exploration concessions to mining lease status. In addition, RPM has applied for the mineral rights to an additional 16,974 hectares in exploration concessions. As of December 31, 2005, DNPM was reviewing RPM's applications. Kinross has reasonable expectation that all applications before the DNPM will be approved.
The Paracatu mine is exposed to limited environmental liabilities related to the following: site water management; main tailings storage area; sulphide tailings storage area; industrial plant site; and airborne dust. Environmental liabilities are being minimized through good management practices.

RPM must pay to the DNPM a royalty equivalent to 1% of net sales. Another 0.5% has to be paid to the holders of surface rights in the mine area not already owned by RPM.


Access to the site is provided by paved federal highways or by charter aircraft that can land at a small paved airstrip on the outskirts of Paracatu. The mine is the largest employer in Paracatu, directly employing 750 workers in what is predominantly an agricultural town (dairy and beef cattle and soy bean crops) located in Brazil's tropical savannah. Average annual rainfall varies between 850 and 1800 mm, the average being 1300 mm, with the majority realized during the rainy season between October and March. Temperatures range from 15(degree) to 35(degree) Celsius.

The mine receives power from the Brazilian national power grid. Some power supply outages have been experienced during the rainy season due to water getting into high voltage equipment, but these have not had a significant impact on production. The mine has a small emergency power capability, used for critical process equipment that cannot be suddenly stopped such as thickeners and CIL tanks

The mine is dependent on rainfall as the primary source of process water. During the rainy season, the mine channels surface runoff water to temporary storage ponds from where it is pumped to the beneficiation plant. Similarly, surface runoff and rain water is stored in the tailings impoundment, which constitutes the main water reservoir for the concentrator. The objective is to capture and store as much water as possible from the rainy season to ensure adequate water supply during the dry season. The mine is permitted to draw make up water from three local rivers that also provide water for agricultural purposes.


Gold mining has been associated with the Paracatu area since 1722 with the discovery of placer gold in the creeks and rivers of the Paracatu region. Alluvial mining peaked in the mid -1800's and until the 1980's was largely restricted to garimpeiro (artisanal) miners. In 1984, Rio Tinto Zinc (Rio Tinto) explored the property using modern exploration methods and by 1987, the RPM joint venture was formed between RTZ and Autram Mineracao e Participacoes (later part of TVX Gold Inc group of companies) constructed a mine and processing facility for an initial capital cost of $65.0 million. Production commenced in 1987 and the mine has operated continuously since then. As of December 31, 2004, the mine since inception had produced 2.985 million ounces of gold from 237 million tonnes of ore.

In 2003, TVX's 49% share in RPM was acquired by Kinross Gold Corporation (Kinross) as part of the merger between Kinross, TVX and Echo Bay Mines Ltd (EB). In November 2004, Kinross and Rio Tinto agreed in principle to Kinross' purchase of Rio Tinto's 51% interest in RPM. Completion of this purchase on December 31, 2004 resulted in Kinross having a 100% interest in RPM and the Paracatu mine.


Rio Tinto was the first company to apply modern exploration methods at Paracatu. The initial production decision was based on a mineral reserve estimate based on 44 drill holes and 458 surface pits (25 meters maximum depth). The deposit was historically drilled off on nominal 100 x 100 meter drill spacing. The exploration history at Paracatu has evolved in lock step with the mine development. As mining advanced and the initial capital investment was recovered, the decision was made to evaluate a deeper horizon ("B1 horizon") and exploration drilling was focused on defining the deposit through drilling accordingly.

As more knowledge was gained through mining of the B1 horizon, the potential of a deeper horizon ("B2 horizon") became increasingly important. As a result of the staged recognition of the mineral reserve potential at Paracatu, several drill holes did not test the entire thickness of the B2 horizon.

After acquiring a 100% interest in RPM, Kinross reviewed the engineering support prepared by RPM in support of a further mill expansion. At the same time, Kinross evaluated the exploration potential at Paracatu and identified two priority target areas:

  • Deepening of holes in the northeast portion of the pit where the full extent of the B2 horizon had not previously been defined and
  • Drilling to the west of Rico Creek where the B2 horizon has been identified with similar characteristics as in the pit area but had been tested with a very limited number of drill holes.
In the first quarter of 2005, Kinross approved a phased exploration drill campaign at Paracatu to upgrade inferred resources west of Rico Creek to a measured and indicated classification. A theoretical $400 pit shell was used to guide the first phase ("Phase I") of the drilling program. A total of 30,000 meters of drilling was planned in Phase I. Subsequent phases would be evaluated based on the Phase I results. The Phase I program was largely complete prior to the November 2005 resource model update however analytical results for 65 of the holes were pending at the time of the update.

In the third quarter of 2005, after reviewing results from Phase I, Kinross planned a second phase ("Phase II") program to explore the potential to increase reserves beneath the existing pit and to define the lateral limits of mineralization external to the $400 pit shell used to constrain Phase I. An additional 20,000 meters of drilling was planned for Phase II.

The drilling for Phase II was completed on December 3, 2005. Phase II added 113 diamond drill holes to the Paracatu database. Phase I and II totaled 267 holes for 48,660 meters. Total exploration costs for Phase I and II were approximately US$ 5.2 million. The outstanding analytical results from Phase I as well as the additional analytical results from Phase II will be used to update the resource model for Kinross' 2005 annual disclosure.


The mineralization is hosted by a thick sequence of phyllites belonging to the basal part of the Upper Proterozoic Paracatu Formation and known locally as the Morro do Ouro Sequence. The sequence outcrops in a northerly trend in the eastern Brasilia Fold Belt, which, in turn, forms the western edge of the San Francisco Craton.

The Brasilia Fold Belt predominantly consists of clastic sediments, which have undergone lower greenschist grade metamorphism along with significant tectonic deformation.

The phyllites at Paracatu lie within a broader series of regional phyllites. The Paracatu phyllites exhibit extensive deformation and feature well developed quartz boudins and associated sulphide mineralization. Sericite is common, likely as a result of extensive metamorphic alteration of the host rocks. Sulphide mineralization is dominantly arsenopyrite and pyrite with pyrrhotite and lesser amounts of chalcopyrite, sphalerite and galena.

The Paracatu mineralization is subdivided into 4 horizons defined by the degree of oxidation and surface weathering and the associated sulphide mineralization. These units are, from surface, the C, T, B1 and B2 horizons. Mining to date has exhausted the C and T horizons. The remaining mineral reserves are exclusively hosted in the B1 and B2 horizons.

Gold is closely associated with arsenopyrite and pyrite and occurs predominantly as fine grained free gold along the arsenopyrite and pyrite grain boundaries or as inclusions in the individual arsenopyrite and pyrite grains. The majority of grains are ultrafine (less than 20 microns) but the few coarse grains that occur are responsible for the highest percentage of the contained gold in the ore.

The mineralization appears to be truncated to the north by a major normal fault trending east-northeast. The displacement along this fault is not currently understood but the fault is used as a hard boundary during mineral resource estimation. The current interpretation is that the fault has displaced the mineralization upwards and natural processes have eroded away any mineralization in this area.


The dominant sample collection method used to delineate the Paracatu resource and reserve model is diamond drilling. Prior to the 2005 drilling program, a total of 696 drill holes totalling 28,317 meters supported the then resource model and reserve estimate. The nominal drill spacing was 100 x 100 meters. Approximately 82 % of the drill holes are large diameter (six inch) drill holes. The remaining holes are either H or N diameter drill holes. The majority of the drill holes are diamond drill holes. A total of 67 RC holes are included in the database. Results from the RC holes indicate that results were 25-30% lower when compared to coincident diamond drill hole results. The database at Paracatu also includes 458 test pits (5,070 meters) which were largely restricted to the C and T horizons that have largely been mined out. Where RC holes have been twinned by diamond drill holes, the RC results have been excluded from the resource and reserve estimation process. Only the RC holes that have not been twinned are included in the estimation process.

In the first quarter of 2005, Kinross committed to a phased exploration program at Paracatu to delineate measured and indicated resources west of Rico Creek. As of December 31, 2005, Kinross had completed 267 diamond drill holes (48,660 meters) which were added to the historical database. Total exploration costs were approximately $5.2 million.

The nominal drill spacing northeast of Rico Creek is 100 x 100 meters. An Optimum Drill Spacing Study commissioned by Kinross established that a 200 x 200 meter five spot pattern (a 200 x 200 m grid plus one hole in the middle) would satisfactorily define indicated mineral resources. This pattern results in a nominal 140 meter hole spacing and represents a departure from historical RPM practices.

Core recovery from the diamond drill programs is reported to be excellent, averaging greater than 95%. RPM employs a systematic sampling approach where the drilling (and test pitting) is sampled employing a standard 1.0 meter sample length from the collar to the end of the hole.
All drill core is logged geologically and geotechnically, recording litho-structural and physical data and recording it in detailed logging sheets. The core is also photographed and a permanent record is maintained in the onsite filing system. All samples are marked and collected by geologists or technicians employed by RPM.

Historical sample preparation reduced each one meter core sample to 95% passing 1.44 mm. Crushed samples were homogenized and split with approximately 7 kg stored as coarse reject. Approximately 200 grams of the remaining sample were split off for ICP analysis and 1.35 kg of sample was split out for Bond Work Index analysis. The remaining sample (4.5 kg) was dried and further reduced to 95% passing 65 mesh. This sample was homogenized and split with 4.2 kg stores as pulp reject and the remaining 300 g was fully analyzed using standard fire assay with AA finish in a series of six, individual 50 grams aliquots. Results from the six individual aliquots were weight averaged together to determine the final grade for each sample.

Kinross completed several studies at the start of the 2005 exploration program. In April 2005, an audit of the RPM mine lab was undertaken to assess lab equipment and procedures. In May 2005, Kinross commissioned Agoratek International (Agoratek) to review sample preparation and analysis procedures with a specific mandate to assess the historical practice of assaying six individual 50 grams aliquots per sample and averaging the results. Agoratek, concluded that three 50 grams analyses would be sufficient for determining the grade of any given sample.
Based on the lab audit and the Agoratek study, Kinross' standardized sample preparation and analytical procedure for the remainder of the 2005 exploration program was as follows:
Samples (typically 8.0 kg) are crushed to 95% passing 2.0 mm and homogenized at the RPM sample preparation lab. Approximately 6 kg of sample is stored as coarse reject; the remaining 2 kg of sample is split out and pulverized to 90% passing 150 mesh. This sample is homogenized and three 50 grams aliquots are selected for fire assaying with an AA finish. The remaining pulverized sample is maintained as a sample pulp reject.

Sample analyses were performed at three separate analytical labs during the exploration program.

Quality control and quality assurance programs were limited during the earlier exploration programs at Paracatu. The dominant quality control procedure involved the use of inter-laboratory check assays comparing results from RPM's analytical lab to Lakefield Research in Canada. Additional check assay work was carried out at the Anglo Gold laboratories in Brazil (Crixas and Morro Velho).

For the 2005 exploration program, three laboratories provided analytical services: RPM's lab, Lakefield and ALS Chemex. All three laboratories have ISO certification.

For the 2005 exploration program, all procedures have been under direct control of RPM and Kinross staff. A quality assurance and quality control program was implemented for the three labs used during the 2005 exploration program. The program consists of inserted certified standards and blanks in the sample streams. All three labs also reported using round robin checks. The labs were visited on an infrequent and unannounced basis by RPM representatives. No major sample preparation discrepancies were noted.


Historically mining at Paracatu has not required blasting of the ore. Ore was ripped using CAT D10 dozers, pushed to CAT 992 front-end loaders and loaded to CAT 777 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. Weathering has led to the development of an oxidized mantle over the sulphide mineralization with thickness varying from 20 to 40 meters. The mine is situated on a gently sloping hillside and historically there has been no waste stripping requirements. Waste stripping will be required as mining advances down dip.

The mill and mine operate 24 hours per day, 7 days per week. The nominal plant throughput is 1.5 million tonnes per month or 18 million tonnes per year, considering the present ore hardness. An ore stockpile of approximately 10 days production is maintained near the processing plant. Its main purpose is to ensure uninterrupted mill feed in the rainy season when some delays may be experienced in the pit during extreme rainfall. During the dry season the stockpile can be used if the pit becomes too dusty. RPM is committed to controlling dust levels on site and in the city.

Ore is crushed and ground prior to introduction into a flotation circuit. The concentrate is treated by gravimetric methods first and the coarser gold is recovered. The concentrate reject from the gravimetric plant is then treated by a conventional cyanidation and carbon-in-leach circuit developed by Rio Tinto. The processing plant, subjected to several upgrades over the mine life, currently processes 18 million tonnes per year ("Mtpa").

Plant throughput has been expanded two times with expansion upgrades in 1997 and 1999. RPM recognized that further plant improvements were necessary in order to maintain current production levels in the face of increasing ore hardness. Exploration drilling successfully traced the Paracatu deposit to depth but sampling indicated that ore hardness increases proportionately with increasing depth from surface.

A study completed in 2004 considered expanding the current 18 Mtpa process facility to 30 Mtpa with the addition of an IPCC system, 38 foot diameter SAG mill and expansion of the existing gravity circuit.

As the study was nearing completion, Kinross and RPM staff were reviewing conceptual models quantifying the potential resource and reserve increase related to exploration activity west of Rico Creek. Preliminary models suggested there was an opportunity to considerably increase the resource and reserve base. This led to the decision to re-evaluate Expansion Project III in light of potential reserve increase resulting from successful exploration programs west of Rico Creek.
A plant capacity scoping study was initiated with the intent of isolating the preferred throughput rate for Expansion Plan III. Key assumptions from the 2004 study were maintained. The plant capacity scoping study recommended that Expansion Project III be increased to a 50 Mtpa throughput rate. The expansion would take place in two stages. The first stage would see construction and commissioning of a separate mill stream anchored by the same SAG mill considered in the 2004 study. This line would have a capacity of 32 Mtpa. Once commissioned, phase two would commence with the shut down, refurbishment and modification of the existing 18 Mtpa plant.

The 18 Mtpa mill will be brought back on line to treat the softer B1 ore, thus a total throughput capacity of 50 Mtpa will be attained.

The additional throughput increase will require additional flotation capacity and upgrading of the existing hydrometallurgical plant and a new tailing pond. The phased approach to construction minimizes production disruption, addresses concerns regarding power and water supplies and reduces total capital costs for the project.

As at December 31, 2005, the net present value of future cash outflows for site restoration costs for Paracatu under CICA Handbook Section 3110 was $12.4 million.

Currently in Brazil there are no laws requiring the posting of a reclamation bond or other financial assurance.


The Paracatu mine currently has a nominal capacity of about 18 million tonnes per year with variations depending on the hardness of the ore, as it affects grinding throughput. In general, ore hardness is expected to increase over the remaining mine life as the pit is deepened and hence throughput will diminish over time.

Based on pilot plant test results and the plant capacity scoping study RPM has recommended construction of Expansion Project III. In the fourth quarter of 2005, basic engineering for Expansion Project III was awarded to SNC Lavalin Engineers and Constructors Ltd. and Miner Consult Engenhania. The Expansion Project III is currently estimated to cost between $400.0 million and $500.0 million, including expansion of plant capacity to 50 Mtpa. If the Expansion Project III is realized, the life of mine for Paracatu will extend to the year 2034, with a life of mine annual production of 370,000 ounces of gold.

In 2005 Kinross spent approximately $21.3 million in capital expenditures attributed predominantly to basic engineering.