Serra Pelada is situated in the mineral prolific Carajas region near the towns of Curionopolis and Parauapebas, Para State, northern Brazil, where access and infrastructure are excellent. There are no weather impediments in the area where Serra Pelada is located.
Serra Pelada Garimpo, 1983
Discovered in 1979, Serra Pelada hosted the largest ever gold rush in Latin America. During the 1980s, up to 80,000 garimpeiros (artisanal miners) produced an estimated 2 million ounces of gold plus platinum and palladium, from a 400m x 300m x 100m hand dug open pit. Garimpeiro production declined due to pit wall collapse and flooding causing the cessation of bedrock mining since the late 1980s.
Vale, which held the underlying title to Serra Pelada until 2007, explored the area from 1980 to 1998, completing more than 200 drill holes in the Serra Pelada mineralised system.
850.425/90 - Colossus concession showing collars of Vale's historical drilling (black), Colossus' Phase I drilling (red), and Colossus' Phase II drilling (aqua)
COOMIGASP, a registered Brazilian cooperative company, was granted Exploration License 1485 (DNPM process 850.425/90) by the Ministry of Mines & Energy in February, 2007. This 100 hectare license is centered on the Serra Pelada pit.
In July 2007, COLOSSUS and COOMIGASP formed a partnership to develop the remaining bedrock mineralisation at Serra Pelada. Under the terms of this joint venture, COLOSSUS will manage and operate the project, earning a majority interest by funding exploration and paying COOMIGASP a premium for the gold reserve established by the joint venture. Details of this agreement may be found in Colossus Minerals Prospectus on www.sedar.com. COOMIGASP will separately develop the 'monteira' (tailings and waste from the Serra Pelada garimpo), with initial financial and technical assistance from COLOSSUS.
774 Hectares of additional ground contiguous to Serra Pelada
In March 2010, the Company successfully acquired 774 Hectares of additional ground contiguous to Serra Pelada. The ownership structure of the total land package remains 75% to Colossus and 25% to Coomigasp.
The mineralization at Serra Pelada is hosted by metasedimentary rocks of the Rio Fresco Group. The lithologies include metaconglomerate, metasandstone, dolomitic carbonate and metasiltstone. About five kilometres east of the deposit, mafic-ultramafic rocks of the Rio Novo Group outcrop, composed of tholeiitic and calc-alkaline lavas with intercalations of banded iron formation, metamorphosed to amphibolite facies. The Rio Novo Group forms the basement in the Serra Pelada area. The nature of the contact between the Rio Fresco Group with the underlying Rio Novo Group is uncertain because of the absence of good exposures.
The metasedimentary rocks of the Rio Fresco Group that overlie the Rio Novo Group at Serra Pelada are, from oldest to youngest, composed of quartzite at the base, carbonates, and metasiltstone at the top. These rocks have been intruded by diorite and subsequently by mafic dykes.
Locally, two intrusive phases have been recognized close to or within the Serra Pelada tenement area: (i) Archean metadiorite; and (ii) mafic dykes. The metadiorite displays evidence of metamorphism through foliation and prograde mineral associations, whereas the mafic dykes are post-metamorphism as they display preserved original randomly-orientated massive igneous textures.
The main Au-Pt-Pd mineralized zone at Serra Pelada cropped out in what is now the northern end of the open pit and was mined over about 300 metres of strike length to the southwest and to depths of around 120 metres in the pit. The Vale and Colossus drilling demonstrate that the mineralization continues at depth under the southern half of the pit, strikes more or less continuously at least 500 metres to the southwest to the boundary of 850.425/90, and is open to the southwest of this boundary. In this area mineralization has been encountered at depths of 250-350 metres below surface. The mineralization has been oxidized by supergene process to depths in excess of 300 metres below surface.
The CMZ overprints metasediments occupying the hinge and inner limbs of a northwest-facing, southwest-plunging, reclined synclinorium that plunges gently southwest from the historical open pit. Some Au-Pt-Pd mineralization to the east and west of the main zone has also been encountered in the drilling. Some of this was mined in sections of the Serra Pelada pit.
The CMZ is characterized by intense carbon and also argillic alteration, inboard of siliceous alteration mantling the synclinorial hinge. The highest grades of gold, platinum and palladium typically occur in the steeply dipping hinge at the contact between the metasiltstone and de-calcified carbonate (“sandstone”). This zone has up to 150 metres vertical extent and in places is more than 50 metres wide. Mineralization is fracture-controlled at all scales, associated with steep, post-D2 faulting that provided conduits for the mineralizing fluids. On the limbs of the syncline, mineralization and alteration form shallowly dipping, broadly stratabound zones, apparently associated with overprinting D2 fold-fault systems.
Au-PGE mineralization is spatially and temporally associated with intense hydrothermal carbon and argillic (kaolinite-mica) alteration and to a minor extent with iron oxide-rich breccias. Alteration is fracture controlled at all scales and is strongest in fault-related siltstone breccias. Carbon-rich and argillic alteration involved de-silicification but broadly synchronous siliceous alteration, mainly replacing calcareous sandstones, discontinuously mantles the CMZ.
The Au, Pt and Pd in the Serra Pelada deposit generally occur together in relatively constant proportions, suggesting that they were deposited from a single hydrothermal fluid, in which they most likely travelled as chloride complexes. The geochemistry of mineralization and alteration is consistent with acidic (pH<4), highly oxidized, metal-transporting brine being introduced along structurally controlled zones, and reacting with the intensely reducing carbon-rich environment concentrated in the synclinal fold hinge.
The Company remains on track for initial production in the third quarter of 2013 at a rate of 250 tonnes per day (“tpd”). Ramp-up plans indicate 1,000 tpd is achievable by the end of the first quarter of 2014.
General Site Plan
Due to better than expected ground conditions, the Company is currently conducting a comprehensive evaluation of a number of different mining methods. Preliminary results from this geotechnical evaluation indicate that a more cost effective alternative to underhand-cut-and-fill may be achievable in certain sections of the mineralization. The Company is evaluating alternatives such as overhand-cut-and-fill and other methods and a final determination will be made ahead of the commencement of production. This evaluation led to the procurement of new equipment and ground support tools which are now on site. The information gathered from this work is assisting management in determining whether an alternative mining method will be viable for the CMZ which could potentially lead to better mining parameters than are currently being modeled.
The bulk sample has been changed in scope as a result of the recognition of additional mineralization during the course of development. The Company encountered mineralization 30 to 40 metres ahead of the CMZ (as that zone is interpreted from surface drilling) and is currently planning to expand the bulk sample in order to incorporate the collection and geological interpretation of this additional mineralization. More details will be provided as this planning is finalized. Preliminary assays have been received indicating previously unmodelled mineralization. While still early stages, the preliminary results suggest a halo of lower-grade mineralization which has the potential to be incorporated into the Company’s mine plan. The Company will release the full results of these assays once they are all available. As a result, management now expects to complete collection of the bulk sample prior to the end of the second quarter. The bulk sample excavation will be extended to become the first mining level and approximately 10,000 tonnes of material will be stockpiled during June and July, in advance of commissioning the process plant.
Results from the expanded bulk sample program will be incorporated into the initial NI 43-101 compliant resource report which will be completed after the processing of the bulk sample and the subsequent analysis of the results. Given the Company’s ability to process material on site commencing in August, management, in conjunction with its consultants, has decided to treat the entire bulk sample through the process plant. Given the new information, and projected turnaround times for overseas shipping, processing and receiving results, management believes the grade of the bulk sample can be ascertained more quickly, and at lower cost, by keeping it on site rather than sending it to a test lab outside of Brazil. Management expects the results from the initial months of mining and processing, inclusive of the results from the on-site processing of the bulk sample, to enable the Company to better project grades and tonnage for production through to the end of December 2014.
The Company has advanced work on the mining plan taking into account the geotechnical information being gathered through the bulk sample collection process. The Company anticipates that a production rate of 1,000 tpd will be achievable with six working faces over two operating horizons. While the Company is still finalizing its mine plan, management remains confident that 1,000 tpd will be reached by the end of the first quarter of 2014.
To date, the Company has currently completed approximately 1,950 metres of total development; 1,250 primary and 700 metres secondary development, compared with 1,800 metres of total development as of March 27, 2013. Development rates have averaged 3.1 metres per day since the beginning of April. Development within the mineralized zone is ongoing and is sufficient to sustain a processing rate of 250 tpd between August and November 2013. Management anticipates achieving a processing rate of 500 tpd in December. Current planning indicates that a total of 1,250 metres of additional development is required between August and the end of November to achieve this rate. This development will be accomplished through ramping up from one to four crews and sets of equipment. Over this 120 day period, management is assuming a development rate of 2.5 metres per day from each development crew. The Company anticipates achieving a processing rate of 1,000 tpd by March 31, 2014. An additional 500 metres of development is required in the first quarter of 2014 to increase the processing rate from 500 tpd to 1,000 tpd. This additional development will be achieved with two crews each achieving 2.8 metres per day while the remaining crews and equipment focus on production mining.
To achieve the development discussed above, the ventilation system requires expansion to provide sufficient air to support four crews and sets of equipment. The expansion work includes widening and concrete lining the artisanal shaft which will be used as a ventilation raise and development of a drift to tie the ramp to this ventilation raise at depth. The ventilation expansion project is 40% complete. Development of this drift towards the ventilation raise is entirely in red siltstone and development rates have been as expected. The Company has completed approximately 60 metres of this drift with approximately 90 metres of development remaining.
The various phases of the process plant construction, along with respective percentages complete are presented in the table below. The ball mill refurbishment and earthworks are complete.
||May 15 Update
|Structural steel fabrication
|Structural, mechanical, piping & electrical installation
|Tailings impoundment facility
As of May 15, 2013, the Company has completed 95% of the concrete placement and civil contractors have been 50% demobilized. Civil construction work is currently focused primarily on the gold room. The Company is well advanced with structural, mechanical, piping and electrical installations in various areas of the project including the primary crusher, transfer tower, conveyors, reagents building, mill feed bin, thickener and gold room. Of the approximately 570 tonnes of structural steel to be erected 70% has been fabricated and 35% has been erected. The thickener fitting and welding is substantially complete and the bridge has been installed. Several pieces of major equipment have been placed (including pumps, tailings sampler, primary and secondary crushers and apron feeder) and preparations to install others are advanced. Please click on the link at the end of this release to see updated pictures of construction progress.
Basic engineering and design of the flotation plant is ongoing and will be complete in the fourth quarter of 2013 after receipt of metallurgical test results. Management’s new plan for treating the bulk sample on site will lead to the availability of more representative metallurgical test material than would be provided from the original plan of testing ten 300 kilogram samples. Construction of the flotation plant is expected to commence in the first quarter of 2014 and is expected to be complete by the end of the first half of 2014.
Surface construction activities continue to focus on the power house and tailings dam. Construction of the power house is 90% complete with the generators now installed. Commissioning of the power house has commenced and 100% capacity is expected by the time the process plant commences operation. It is important to note that 50% power generation capacity is sufficient to operate all current mine services and infrastructure. The power house design was modified to allow connection with a 34.5 kV transmission line constructed by Equatorial Energia SA (“Equatorial Energia”) (formerly Centrais Eléctricas do Parà SA or CELPA). The power supplied by Equatorial Energia will be lower cost and will be backed up by power from the diesel generators, which are being commissioned as noted above. Equatorial Energia has recently advised the Company that connection to the grid is now scheduled by the end of June. Increased power consumption will not occur until the mill building is operational early in the second half of 2013. Therefore, this delay in connecting to the grid will not have a material impact on the Company’s construction schedule or costs. Tailings’ dam construction is approximately 20% complete and remains slightly ahead of schedule. Earthworks are well underway and the completion of the tailings dam is on track to be completed in conjunction with mill commissioning.