Woodstock Manganese Project
The Woodstock Project, which contains the Plymouth Mn-Fe deposit, is located in Carleton County, southwestern New Brunswick, Canada, approximately 5 km west of the town of Woodstock, New Brunswick.
The Woodstock Project consists of Mineral Claim 5472 comprising 232 mineral claims that cover approximately 5,800 ha of surface area. The Plymouth Mn-Fe deposit is located in the southwestern area of the northernmost claim block, less than one km north of Highway 95 to Houlton, Maine, and is accessed by the Plymouth Road, which is located just west of the deposit.
The information relating to the Woodstock property and Plymouth deposit in the following sections has been largely extracted from the Woodstock Report dated July 10, 2014 that was prepared by Dharshan Kesavanathan, P.Eng., Laszlo Bodi, P.Eng., Michael Cullen, M.Sc., P.Geo, Mike McLaughlin, P.Eng. and Wenchang Ni, P.Eng. of Tetra Tech WEI Inc., Qualified Persons defined by NI 43-101, as filed on SEDAR on July 22, 2014. Information pertaining to the Mineral Resource Estimate of the Plymouth deposit has been extracted from the Woodstock Resource Report dated May 6, 2013 that was prepared by Michael Cullen, P.Geo. and Andrew Hilchey, P.Geo., Mercator Geological Services Limited and Stephanie Goodine, P.Eng. of Thibault and Associates.
The Woodstock Report (2014) and the Woodstock Resource Report (2013) are intended to be read as a whole documents, and sections should not be read or relied upon out of context. The technical information is subject to the assumptions and qualifications contained in the Woodstock Reports and the Woodstock Resource Report (2013). For readers to understand the technical information on Woodstock in this document, they should read the Woodstock Report (2014) and the Woodstock Resource Report (2013) filed under Minco’s profile on www.sedar.com in its entirety, including all qualifications, assumptions and exclusions that relate to the technical information set out in this document.
The Woodstock Project is easily accessible, with the Trans-Canada Highway being located approximately 4 km to the east and Highway 95 in Canada, which extends westward to the U.S. border, being located less than 1 km north of the Plymouth Road that crosses the property.
Mineral Resource Estimate
The mineral resource estimate described in the Woodstock Resource Report is based on validated results of the 2011 and 2013 drilling programs carried out by BMC, and Minco, plus validated results of five drill holes and two trenches completed by MRR in 1987.
The Mineral Resource estimate for the Plymouth deposit, contained in the Woodstock Resource Report, reflects a 3.5% manganese cut-off value and has an effective date of July 10, 2014. The 3.5% cut-off, updated from the 5% manganese cut-off used in a previous May 6, 2013 Plymouth deposit resource statement (Cullen 2013), is based on parameters established by the Woodstock PEA and reflects a reasonable expectation of economic viability based on market conditions and open pit mining.
Plymouth Manganese-Iron Deposit Resource Estimate – July 10, 2014
- Tonnages have been rounded to the nearest 10,000 t.
- Mineral resources that are not mineral reserves do not have demonstrated economic viability.
- This estimate of mineral resources may be materially affected by environmental permitting, legal, title, taxation, sociopolitical, marketing, or other relevant issues.
Total Contained Manganese at the 3.5% Inferred Resource Statement Cut-off Value
The Plymouth deposit, as currently defined by a 3.5% manganese cut-off value, remains open, both along strike and down dip. Further core drilling to assess deposit extensions along strike and down dip in these areas is warranted. Infill drilling within current resource model limits, at a 50-m intercept spacing, would be necessary to upgrade much of the currently defined Inferred Mineral Resource to the Indicated Mineral Resource category of confidence.
On the basis of poor support documentation, Mercator did not include results from 1950s era drilling programs in the project database used in the current resource estimate reported in the Woodstock Resource Report. Only data from the MMR programs in 1985 and 1987, plus the Canadian Manganese programs in 2011 and 2013 are included in the current resource estimate database, which is addressed below.
The Plymouth deposit was modeled as a folded, stratiform manganese-iron deposit occurring within a northeast striking, steeply dipping host sequence of red and grey siliciclastic sedimentary rocks using GEOVIA (formerly Gemcom) Surpac™ (Surpac™) v. 6.4.1 deposit modeling software. Drilling-defined mineralization within the resource estimate block model occurs along a 700 m strike length and reaches a maximum width of approximately 200 m in the central deposit area. Inverse Distance Squared (“ID2”) interpolation methods and 3 m downhole assay composites were used to assign manganese, iron, and specific gravity values within the block model, with block dimensions of 10 m (x) by 10 m (y) by 10 m (z). The predominant manganese compound in the Plymouth deposit is manganese carbonate (MnCO3). Metal grade assignment was peripherally constrained by two separate wireframed solid models based on sectional geological interpretations for the Plymouth deposit and a minimum included grade of 5% manganese over 12 m in the respective downhole direction of each drill hole.
The main resource solid defines a folded geometry, with near vertical to steeply dipping eastern and western limbs, and a broad interpreted closure zone. The eastern fold limb is recognizable for only 400 m of block model strike length. The second resource solid was developed along the peripheral limits of the western limb of the main solid to constrain additional stratiform mineralization that shows less continuity and lower average manganese grade than that of the main solid. To assess the distribution of reduced and oxidized host stratigraphy an Inverse Distance Cubed (“ID3”) interpolated model was developed from logged BMC numeric values for a percentage of red rock. Results from 639 separate laboratory determinations of specific gravity were composited at a 3-m downhole support length and were then used to develop the interpolated specific gravity model. The resource estimate and supporting block model were checked by comparison with geological and assay sections, as well as against results of grade interpolation using Ordinary Kriging (“OK”) methods. A very good correlation exists between results of the two interpolation methods and the results of section checking showed good model correlation to drill hole datasets.
The Mineral Resource Estimate for the Plymouth deposit, contained in the Woodstock Technical Report, reflects a 3.5% manganese cut-off value and has an effective date of July 10, 2014. The 3.5% cut-off, updated from the 5% manganese cut-off used in a previous May 6, 2013 Plymouth deposit resource statement (Cullen 2013), is based on parameters established by the Woodstock PEA and reflects a reasonable expectation of economic viability based on market conditions and open pit mining methods.
The Plymouth deposit, as currently defined by a 3.5% manganese cut-off value, remains open, both along strike and down dip. Further core drilling to assess deposit extensions along strike and down dip in these areas is warranted. Infill drilling within current resource model limits, at a 50-m intercept spacing, would be necessary to upgrade much of the currently defined Inferred Mineral Resource to Indicated Mineral Resource status.
An earlier mineral resource estimate of Inferred Resources was issued by Mercator on May 6, 2013 comprising 43.7 Mt, grading 98% manganese, and 14.29% iron at a 5% manganese cut-off in the inferred category (or 9.62 Blb of contained manganese). This estimate was superseded by the Mineral Resource Estimate contained in the Woodstock Technical Report. The only difference between the 2013 estimate and the 2014 estimate is that a 3.5% manganese cut-off value was used to define the 2014 estimate contained in the Woodstock Technical Report.
Accessibility, Climate, Local Resources, Infrastructure and Physiography
Canadian Manganese has the exclusive right to explore for minerals within the Woodstock Project boundaries, and has acquired the surface rights over an area measuring 52 hectares in size that covers the northern portion of the Plymouth deposit. Land access with surface right holders has been secured, as and when necessary, for the purpose of mineral exploration on those areas where Canadian Manganese does not already own the surface rights. The portion of the property for which Canadian Manganese purchased surface rights is subject to a 1% gross sales royalty payable upon commencement of commercial production, with Canadian Manganese retaining certain rights to buy back one half of the royalty.
The mineral rights were acquired by purchasing the original claim block of 21 claim units covering the Plymouth Mn-Fe deposit and most of the Hartford Mn-Fe deposit on August 4, 2010 from Mineral Resource Research Ltd. (“MRR“), a private company based in Fredericton, New Brunswick. After acquiring the initial MRR property, additional mineral claims were staked in 2010 and 2011 to cover previously documented Mn-Fe occurrences plus extensions of associated gravity and magnetic anomalies that extend for up to 20 km along strike to the southwest. Extending the land position provided coverage of a 20 km long corridor extending from the known deposits to the border with the State of Maine (USA). Mineral Claim 5472 is in good standing with sufficient excess assessment credits to retain mineral rights without additional property expenditures required before November 14, 2024. The Mineral Claims requires annual renewal fees that increase periodically. Renewal fees in 2016 were $4,640.
The Woodstock Project is easily accessible, with the Trans-Canada Highway being located approximately 4 km to the east and Highway 95 in Canada, which extends westward to the U.S. border, being located less than 1 km north of the Plymouth Road that crosses the property.
The property is well-positioned with respect to infrastructure. A railway line is accessible in Houlton, Maine, 16 km to the west, and electrical grid power is readily available within the limits of the Woodstock Project. The town of Woodstock is located approximately 5 km to the east, accessible year-round by paved roads, and has a population of approximately 5,000. It offers basic amenities and is a regional hub of commerce. The city of Fredericton is located 105 km along the Trans-Canada Highway to the south and is a large centre that has a population of 56,224 people which could supply a trained workforce, and has a university, hospital and all amenities and supplies necessary to support a potential mining operation.
The climate in northern New Brunswick is characterised by relatively cool, northern Atlantic temperate conditions with a short summer season from July through early September and a long winter period from November through late March or early April. Environment Canada records show the daily mean temperature during the winter months to be -5° C, ranging from 0° C to -11.5°C, and daily mean temperature from May to October is 10° C, range from 6.4° C to 19.3° C. Daily winter minimums can exceed -30° C and summer daily maximum values in the 25° C or higher range also occur. Average annual precipitation ranges from 77 cm to 107 cm with much of this occurring as snow. Exploration activities can be carried out in all seasons in this area, assuming that appropriate allowances are made for heavy snow conditions during winter months and thawing ground during spring break-up. The latter period can present substantial challenges due to wet and soft ground conditions that can make certain less developed roads temporarily impassable.
For the most part, the terrain is gently rolling with wooded hills covered by stands of predominantly mixed deciduous and evergreen trees being present, and the elevation of the property is approximately 124 m above mean sea level. Low-lying and low relief areas are commonly cleared and used for farming. While most residential properties are limited to homesteads established prior to the mid-1900s, there are also local housing developments comprised of modern suburban housing, particularly within the most northern portions of the property near Hartford. Several rivers transect the properties and typically have incised gorges in the otherwise gently rolling topography, the largest of these is the Meduxnekeag River that flows east to the St. John River.
The history of exploration and mining at the Woodstock Project was poorly recorded for the period prior to 1970, but historical operations at Iron Ore Hill and in the Woodstock area included development and production of approximately 70,000 tons (63,497 tonnes) of iron ore between 1848 and 1884. It is understood that this ore was locally smelted. The Mn potential of these occurrences may not have been fully appreciated until 1936, when the Geological Survey of Canada (“GSC“) published geological mapping for the area. This work highlighted several occurrences of Fe formation including some of the main deposits in the Moody Hill and Iron Ore Hill areas. This work included chemical analyses of several of the Fe formations and highlighted the high Mn contents of the material with reported ranges between 10.48% and 15.0% Mn. In 1943, the ores were assessed by Noranda Mines Limited using flotation technology to produce a Mn and Fe concentrate. Also in that year, regional scale mapping was completed in (1943) for the State of Maine and in 1947, the Maine Geological Survey published a review of the Mn deposits of Aroostook County.
In 1952, the New Brunswick Resources Development Board completed a review of New Brunswick Mn occurrences and in 1954, the GSC completed a preliminary review of the Woodstock area Mn occurrences. The United States Bureau of Mines and Maine Geological Survey also initiated studies of similar Mn deposits in Aroostook County, Maine in 1952 and work undertaken between 1952 and 1962 included metallurgical studies on mineralization from the Maple Mountain-Hovey Mountain deposits, description of ores from the Littleton Ridge Mn deposit, bulk sampling of the Dudley Mn deposit, investigation of various Aroostook County occurrences, and detailed geological investigation of the Maple and Hovey Mountain area deposits.
Between 1953 and 1960, the deposits were held by Strategic Manganese Corporation, a subsidiary of Stratmat Limited (“Stratmat“). While conducting a gravity survey southwest from the Iron Ore Hill area to the Maine border, Stratmat discovered the North and South Hartford deposits, as well as the Plymouth Mn-Fe Deposit. Over the period of 1953 to 1957, Stratmat completed various metallurgical investigations and geological and magnetic surveys, and 34,021 feet (10,370 m) of drilling, including 17,388 feet (5,300 m) on the Plymouth Mn-Fe Deposit. From this exploration, Stratmat produced a historical resource estimate for the Plymouth deposit of 51,000,000 tons (46,266,421 tonnes) of 13.3% Fe and 10.9% Mn. They also estimated the Woodstock deposits to a depth of 500 feet (152.4 m) to contain 214 million tons (194,137,534 tonnes) of 13% Fe and 9% Mn. See “Historical Estimates” below.
Over the period 1965 to 1968, the Chemical Engineering Department of the University of New Brunswick undertook three investigations of the Mn ores. These investigations included examination of possible chemical processing techniques of the ore that included chemical leaching with sulfuric acid and sulfidation, as well as upgrading by agglomeration as an alternative to flotation.
In 1968, the Geological Survey published a Memoir on the Woodstock area that included a regional geological map showing locations of the various Mn-Fe prospects in the area. This report provides detailed descriptions of the main Woodstock Property deposits and documents the location of several Mn-Fe occurrences located southwest of the Plymouth deposit and extending to the Maine border.
In the early 1970’s, Mandate Refining Company held the claims and worked towards development of a method of roasting pyritic waste and Mn-Fe ore. This was unsuccessful and the claims were abandoned.
In 1972, the New Brunswick Department of Natural Resources published a geological report on the stratigraphy and structure of the area. This report included several geological maps showing locations of Mn-Fe occurrences throughout the area, including those covered by the current Woodstock Project held by Buchans.
Between 1976 and 1980, Minuvar Limited held the claims and undertook geological mapping and geochemical sampling of available trenched and outcropping bedrock exposures in 1976. It also subsequently conducted magnetometer and very low frequency electromagnetic (“VLF-EM“) ground geophysical surveys over the Plymouth deposit. In 1978 and 1979, one inch to quarter mile geology maps for the area were published by the New Brunswick Geological Survey.
In 1984, MRR staked the Mn-Fe deposits and in 1985, completed detailed geological mapping and trenching over the Plymouth deposit and drilled one hole to test the known deposit. This hole missed the zone as it was drilled sub- parallel to strike.
In the fall of 1985, the NBDNRE collected samples from the Plymouth deposit for submission to the New Brunswick Research and Productivity Council (“RPC“) for mineralogy studies and chemical analysis.
In 1986, a sampling program was completed over the Plymouth and Hartford deposits funded by the Canada-New Brunswick Mineral Development Agreement. Work was completed by Atlantic Analytical Services (“Atlantic Analytical“) and the RPC. Five samples from Plymouth and three samples from South Hartford were collected for mineralogy and grade determinations, including five 200 kg samples collected from five trenches excavated and sampled in January of 1986. The “original trench” previously sampled by the NBDNRE in 1985 was not sampled during this sampling campaign. This work was reportedly undertaken during a period of “heavy snow fall” that hindered the program.
Results showed that all of the Plymouth samples were of inferior quality, assaying an average of only 5.13% Mn, and one of the samples assayed as low as 0.46% Mn and “contained substantial quantities of mud and soil”. These same samples were used in a follow-up study by the Process Studies Group of the Mineral Resources Branch of NBDNRE that included various leach tests. The reported head grade of the sample was 7.29% Mn and 11.3% Fe (O’Donnell, 1988).
In 1986, funded by the Canada-New Brunswick Mineral Development Agreement, Witteck Development Inc. (“Witteck“) of Mississauga, Ontario was contracted by the Department of Supply and Services of the Government of Canada to undertake a detailed processing study using the Atlantic Analytical samples collected from the Plymouth deposit. Witteck completed a detailed investigation that included metallurgical test work and an economic evaluation of selected processing options. Head assays for the Plymouth samples were determined to range from 6.27% to 8.41% Mn and averaged 7.2% Mn.
In 1987, MRR also completed a ground magnetometer and VLF-EM survey over the Plymouth deposit. The magnetometer survey was successful in outlining the Plymouth deposit with results obtained being comparable to those of earlier surveys.
In 1988, MRR undertook a comprehensive technical program to evaluate the Plymouth deposit in an attempt to establish an accurate description of the deposit, including potential grade and tonnage aspects. This program included bulk sampling, trenching, core drilling and geochemical analyses. Highlights include excavation of two trenches across the deposit and drilling of two drill holes beneath each trench to allow interpretation of sections across the deposit at depth.
A total of five holes (DDH-87-1 to DDH-87-5) were drilled, totaling 2,086 feet (636 m). Based on this work, MRR completed a resource estimate for part of the deposit that totaled 10,078,875 tons (9.1 million tonnes) averaging 11.89% Mn (Roberts and Prince, 1988).
In 1991, an interim report was prepared on an investigation to evaluate the use of microwave-hydrochloric acid digestion processing of the Woodstock ores. In 1991, MRR contracted Industrial Research and Development Company Ltd. to evaluate the use of microwave-hydrochloric acid digestion processing of the Woodstock ores.
In 2007, a thesis study of the Woodstock deposits was initiated by Mr. Bryan Way in pursuit of a Master of Science degree in geology at the University of New Brunswick under the supervision of Dr. David Lentz. This research lead MRR to reacquire claims over the Plymouth and Hartford deposits by staking in 2008 and MRR made various archived samples and drill cores available to Mr. Way for sampling and study.
The project was acquired by Canadian Manganese in August 2010. The mineral rights were acquired by purchasing the original claim block of 21 claim units covering the Plymouth Mn-Fe deposit and most of the Hartford Mn-Fe deposit on August 4, 2010 from Mineral Resource Research Ltd. (“MRR”), a private company based in Fredericton, New Brunswick.
Historical Estimates: The above summary of the history of the Woodstock Project contains historical estimates, including estimates of the quantity and grade of deposits on the Woodstock Project.
Readers are cautioned that the historical estimates contained in the above summary are based on data obtained and prepared by previous operators and neither Canadian Manganese nor its predecessors have located original assay sheets or details of the estimation methodology, nor the key assumptions or parameters, underlying the estimates. A qualified person has not done sufficient work to verify or classify the historical estimates as current mineral resources. Canadian Manganese is not treating the historical estimates as current mineral resources in accordance with NI 43-101, and these estimates should not be relied upon.
Geological Setting, Mineralization and Deposit Types
Government mapping in the area of the Woodstock Project shows it to be underlain by a belt of Ordovician and Silurian siltstones and slates collectively referred to as the Aroostook-Perce belt. Late Ordovician to Early Silurian sediments of the Matapedia Group’s Whitehead Falls Formation are overlain by Early Silurian sediments of the Perham Group’s Smyrna Falls Formation and are laterally extensive throughout the property and over much of western and northwestern New Brunswick and Maine.
The Woodstock Project Mn-Fe deposits are interpreted to represent a series of Early Silurian manganiferous banded iron formations (“BIFs”). Six main Mn-Fe deposits were identified by gravimetric survey results from the mid- 1950s and are defined as being large, lenticular-shaped bodies within the Silurian Smyrna Mills Formation. These deposits are interpreted to have formed in a shallow marine basin during the Taconic Orogeny and are in sharp contact with units of red or green shale. Stratigraphic lensing and compositional variation of the manganiferous BIFs has been interpreted to indicate that the deposits are stratigraphically separated and not one continuous unit. The current orientation of bedrock units is primarily a function of two folding generations. F1 folds trend northeast, are slightly overturned south of the Plymouth Mn-Fe Deposit and have axial planes ranging from nearly vertical to 85° northwest. Fold axes plunge shallowly (less than 5 degrees) to the northeast or southwest. F2 folds overprint F1 structures and have axial planes trending northwest (approximately 320°) and dipping steeply (approximately 80°) north. Both sets of folds were generated during the mid-Devonian Acadian Orogeny and were affected by associated regional sub-greenschist metamorphism.
The White Head Formation consists of dark grey to bluish-grey fine-grained argillaceous limestone with interbedded calcareous shale. The Smyrna Mills Formation is composed of dark grey non-calcareous silty shale with minor layers of green and red mudstone, and associated ferro-manganiferous siltstone. There is great variation in shale and/or siltstone in the Smyrna Mills Formation and this is interpreted to indicate variable ocean redox conditions during deposition of the host sequence. This is evidenced by the occurrences of BIFs at Plymouth, Iron Ore Hill, South Hartford, and Green Road that are commonly in sharp contact with units of red or green shale, or a combination of the two.
The Plymouth Mn-Fe Deposit has been described as an assemblage of Fe and Mn oxide and carbonate-silicate- oxide facies rocks that formed within a shallow marine basin, an interpretation supported by the presence of asymmetrical ripple marks within the surrounding strata initially described the Plymouth BIF as a series of sedimentary-volcanic units, but alternative hypotheses suggest the Mn-Fe could have originated from a variety of sources including oceanic Mn-Fe hydroxides and/or the weathering of terrestrial bedrock.
Historical interpretation of the mineralization of the Plymouth Mn-Fe Deposit indicated that the Mn-Fe mineralization can be subdivided into Mn-Fe oxide, silicate-carbonate-oxide, and carbonate facies. These stratiform deposits are analogous to the Type IIA deposits of bedded Mn oxides and carbonates. The Fe-Mn oxide facies present on the Woodstock Property is represented by red to maroon siltstone and red chert and is characterized by the mineral assemblage magnetite, hematite, braunite (Mn+2Mn+36[O8SiO4]) and bixbyite ([Mn,Fe]2O3) and ranges between 30% and 80% Fe-Mn oxides. Fe and Mn mineralization is also present in the form of rhodochrosite (MnCO3) and minor sursassite (Mn2Al3[(SiO4)(Si2O7)(OH)3]) crosscuts syngenetic Fe-Mn mineralization in the Plymouth deposit. Layers of Fe-Mn mineralization are also locally observed to be crosscut by veins of quartz, quartz-carbonate, chlorite, and sulfide.
Following the work completed by Canadian Manganese and consultants on the Plymouth deposit since 2011, it has been found that the manganese mineralization in both the red and grey siltstones is dominated by manganese carbonate in the form of rhodochrosite. The iron mineralization in both the red and grey siltstones was found to be different, with the dominant iron minerals in the red siltstone found to be predominantly oxides, in the form of hematite, magnetite and ilmenite; whilst the dominant iron mineral in the grey siltstone was found to be predominantly carbonate, in the form of siderite.
The manganese contained in the Plymouth deposit is predominantly in the form of a carbonate (rhodochrosite) whilst the iron exists in both oxide (hematite, magnetite and ilmenite) and carbonate minerals (siderite). The deposit type is sedimentary in origin and of the stratiform, banded Mn-Fe formation (BIF) type. The host sequence consists of Silurian red and grey siliciclastic to calcareous siltstones and shales that have been metamorphosed under lower greenschist facies conditions. In addition to the main oxide, silicate and carbonate facies Mn-Fe concentrations, host rocks contain minor magnetite and traces pyrite in grey siltstone and black shale intervals. The Mn rich iron formation deposits occur in stratiform bodies and represent spatially distinct deposits that accumulated contemporaneously with surrounding sedimentary strata. Fe and Mn are considered to have been deposited from seawater in an oxidising environment and host strata have subsequently been structurally thickened through Mid- Devonian folding and faulting related to the Acadian Orogeny. Some subsequent remobilization of Mn has occurred and resulted in re-deposition of Mn oxides in fracture zones.
Exploration and Drilling
In 2011, Canadian Manganese carried out a five-hole (1,040 m) core drilling program on the project in 2011 consisting of five holes.
These holes were designed to assess the historic Plymouth deposit, as identified by a magnetic survey carried out by MRR in 1987, and to confirm assay results reported by MRR in 1988. The program was managed by employees of BMC with logging and sampling conducted by a Canadian Manganese geologists and technicians.
Assays from the initial three holes demonstrated grade and continuity over large widths. Significant intercepts of the program included 11.41% manganese over 45.0 m in Hole 11-006, 11.43% manganese over 89.0 m in Hole PL- 11-007, and 9.22% manganese over 63.0 m in Hole PL-11-008. Additional drill results included results for two intersections in Hole PL-11-009. The upper intercept from a depth of 10 m to 54 m returned 8.61% manganese over 44.1 m and the lower intercept from 69 m to 147 m returned 51% manganese over 78.0 m. Hole PL-11-010 also included two intersections with an upper intercept from 10 m to 111 m returning 11.27% manganese over 101.0 m and a lower intercept from 153 m to 231 m returning 11.67% manganese over 78.0 m.
True widths of the mineralized intercepts are estimated to be approximately 87% of the reported drill core lengths. Drilling was completed on two sections spaced approximately 100 m apart and was designed to confirm the deposit’s grade and thickness and to collect fresh core samples for metallurgical testing.
In 2013, Canadian Manganese completed 15 diamond drillholes totaling 4,082 m along 7 sections transecting the mineralization, spaced at approximately 100 m intervals over the length of the deposit across the deposit as a basis for resource estimation of the Plymouth deposit to the Inferred category. The program was planned by Mercator with input from BMC technical staff to provide drill hole information sufficient for the purposes of completing a NI43-101 compliant resource estimate.
The resulting 2014 resource estimate was compiled from available verifiable historic data, including data collected by previous trenching and drilling by MRR in 1987 (5 holes totaling 636 m) as well as drilling data collected by Canadian Manganese in 2011 (5 holes totaling 1,040 m) and during 2013 (4,082 m).
In the 2014 PEA, TetraTech evaluated two mining operation scenarios—1,500 t/d mill throughput and 3,000 t/d mill throughput—based on the same resource model and overall slope angle. The 3,000 t/d scenario was utilized as the base case for this study.
The mining operation will use a conventional open pit mining method, off-highway haul trucks, and hydraulic excavator. The waste rock and Mineral Resource will be drilled and blasted using typical grade-control methods and blast hole sampling. The open pit has been designed using a two-stage approach. The first stage identified the optimum pit shell using the Lerchs-Grossman pit optimization algorithm in GEOVIA (formerly Gemcom) Whittle™ v.4.5 software (Whittle™). The second stage involved developing the preliminary ultimate pit design, phase planning, and production schedule; selecting equipment; and estimating the capital and operating costs.
A buffer stockpile strategy has been proposed as an effective solution to improve the economic outcomes for both operational scenarios. A total of eight separate stockpiles are included in the mine plan and consist of four red mineralized stockpiles and four grey mineralized stockpiles, both varying by grade range. In Years 1 to 13 the most economical mineralized material available, either from direct mining activity during mine Phase 1 to 3 or from stockpile depletion, is utilized to supply the mill. In the post-mining years beyond Year 13, only stockpile depletion material is used to supply the mill. The most economical mineralized material is prioritized as defined by the mine schedule. In general, the red mineralized material stockpiles are depleted first until their grade drops to a level which permits the introduction of grey mineralized stockpile material depletion to begin.
Metallurgical and hydrometallurgical testing was carried out on core samples from the 2011 drilling program for the Plymouth deposit. From the 2011 drill core samples, a weighted average composite sample of all five drill holes was split and blended to represent the general properties of the Plymouth deposit has been carried out. This sample is referred to as the “bulk” composite sample. Two additional weighted average composite samples were split and blended to generate a brick-red siltstone hosted composite sample, referred to as the “red” sample and a green-grey siltstone hosted composite sample, referred to as the “grey” sample. Along with the bulk composite sample, the red and grey composite samples were tested to assess the variability of certain process parameters with respect to these sections of the Plymouth deposit.
X-ray diffraction (“XRD”) analysis was completed on each of the composite samples to identify major and minor mineral phases present in each of the samples. Rhodochrosite or manganese carbonate was the only manganese mineral detected by the scan in all three samples, indicating that manganese in the Plymouth deposit exists in the reduced manganese (II) carbonate state. Iron was also reported as having a strong presence in all composite samples and was found to be present in both oxide form (hematite, magnetite, ilmenite) and as a carbonate (siderite). Oxide forms of iron minerals were generally dominant in the red composite sample, while the grey composite sample contained a higher proportion of siderite. Gangue minerals generally include quartz, dolomite, hydroxylapatite, and various phyllosilicate type minerals.
Mineral Processing and Recovery Methods
The production of highly-purified manganese sulphate solution using hydrometallurgical processing technologies provides alternative production options for the primary production of EMM from the Plymouth deposit, with opportunities for co-production of alternative manganese products such as electrolytic manganese dioxide (“EMD”), chemical manganese dioxide (“CMD”), manganese sulphate and other manganese chemicals.
The selection of EMM as the final product from hydrometallurgical processing of the Plymouth deposit for the PEA is based on manganese product market factors; however, it is noted that the hydrometallurgical block diagram developed for recovery of EMM from processing of material from the Plymouth deposit is readily amendable to reconfiguration for production or co-production of alternative manganese products as listed above with limited impact on the overall operating and
capital costs for the Project.
The presence of manganese predominately as manganese (II) carbonate in the Plymouth deposit precludes the requirement, as in the case of manganese oxide feedstocks, for a reduction step to convert manganese (IV) to manganese (II) using high-temperature pyrometallurgical systems, which are subject to significant operating costs associated with fuel and environmental controls, or hydrometallurgical methods involving the addition of a reducing agent into the leaching stage, which increases operating costs and generates dithionate ions in the leach solution, requiring advanced treatment methods for effluent disposal.
The hydrometallurgical process proposed for the production of EMM from the Plymouth deposit is similar to that used by commercial plants in China for hydrometallurgical processing of manganese carbonate feedstocks; however, the proposed process incorporates improved measures for environmental sustainability and a novel arrangement of unit operations for iron precipitation to accommodate the high iron content of the Plymouth deposit. Pre-concentration of the Plymouth deposit using magnetic separation technology to upgrade the manganese content and selectively eject acid-consuming gangue minerals has been included as an integral part of the preliminary process block diagram. For the base case on average over the life of the project, the manganese content of the mill feed is upgraded from 9.86% to 13.35% at 85.7% recovery while rejecting just over 35% of the overall mass.
Market Studies and Contracts
The primary focus for development of the Plymouth deposit is the production of EMM, which is a commercially important industrial metal commonly used as a steel additive particularly in the production of 200-series stainless steels. Manganese has been defined by the Canadian and US governments as a strategic metal that is essential for national defense, aerospace, technology and energy that is highly susceptible to supply interruptions due to the lack of domestic production. Currently, 100% of the EMM that is consumed in North America and Europe is imported from other countries, most notably from China which controls over 95% of the global supply of EMM, and from South Africa—the only other producer outside of China.
Pre-concentration of the manganese content of the Plymouth deposit using magnetic separation also results in the production of a relatively small tonnage of iron ore, which represents less than 1.5% of the total revenue for the Project and less than 10% of the total contained iron in the feed to the processing plant. To date, process development studies have focused solely on the production of EMM and moving forward opportunity studies are planned to identify processing methods and potential product markets for the balance of the iron within the Plymouth deposit and for production of other manganese chemicals.