The Birch Lake exploration target includes the area inside the Birch Lake model perimeter surrounding the Indicated and Inferred Mineral Resources. The tonnage and grades of the Birch Lake exploration target could range from 222 to 334 million tons grading 0.33 to 0.50 %Cu, 0.11 to 0.16 %Ni, and 0.39 to 0.58 ppm TPM.
About the Resource Estimates
The figures for resources presented herein, including the anticipated tonnages and grades that may be achieved or the indicated level of recovery that may be realized, are estimates, and no assurances can be given that they will be realized during production. Such estimates are, in large part, based on interpretations of geological data obtained from drill holes and other sampling techniques. Actual mineralization or favourable host rock units may be different from those predicted. It may also take many years from the initial phase of drilling before production is possible, and during that time the economic feasibility of exploiting a deposit may change.
The Company's business of mineral exploration has a high level of inherent risk. Although the Company is optimistic about the potential of many of its projects, there is no guarantee that any mineral deposits will be economically feasible and that these deposits will be put into production. The Company's exploration and development activities may also be affected by a number of risks, including environmental, metallurgical, financing, permitting, approval, legislative and other government risks which are normal to the industry and are referenced in greater detail in the Company's Annual Information Form.For the purposes of assessing reasonable prospects of economic recovery and appropriate cut-off grade, the following assumptions were used:
- Average mining costs: $16/t (all underground mining; long hole open stoping with backfill)
- Average process costs: $12/t (flotation concentrate followed by hydrometallurgical processing using Teck Resources Limited ("Teck") CESL™ process [ 6 ])
- G&A costs: $2/t
Recovery Recovery Recovery Metal Price (US$) Concentrate CESL Global Payable Copper $3.00/lb 94.3% 96.3% 90.8% 100.0% Nickel $9.38/lb 72.0% 95.6% 68.8% 80.0% Platinum $1840/troy oz 93.0% 59.4% 55.2% 80.0% Palladium $805/troy oz 90.0% 70.7% 63.6% 80.0% Gold $1050/troy oz 85.0% 74.5% 63.3% 80.0%Table 7b - NSR calculation parameters, Birch Lake Deposit
Recovery Recovery Recovery Metal Price (US$) Concentrate CESL Global Payable Copper $3.00/lb 94.3% 96.3% 90.8% 100.0% Nickel $9.38/lb 60.0% 95.6% 57.4% 80.0% Platinum $1,840/troy oz 93.0% 59.4% 55.2% 80.0% Palladium $805/troy oz 90.0% 70.7% 63.6% 80.0% Gold $1,050/troy oz 85.0% 74.5% 63.3% 80.0%[ 6 ]Teck has developed a hydrometallurgical process named CESL™, that effectively recovers copper, nickel and PGM's from bulk copper-nickel-PGM concentrates, which Duluth and Twin Metals are considering as a concentrate processing alternative. Concentrate from the Maturi group of deposits has been successfully procesed at bench and pilot scale at Teck's hydrometallurgical facility in Richmond, BC with average recovery of metal from concentrate into saleable product form as reported in Table 7a and Table 7b. For the non-legacy assay data utilized in these resource estimates, half core samples were prepared at ALS Minerals laboratories in Thunder Bay and then shipped to the ALS analytical facilities in Vancouver. Samples were analyzed for Au, Pt, and Pd using a 30g standard fire assay with an ICP-AES finish. An additional 33 elements were analyzed for using a four acid (near total) digestion and a combination of ICP-MS and ICP-AES. ICP over-limits for copper and nickel are re-analyzed using dissolution four acid (near total) digestion followed by ICP-AES or AAS. The remaining half core samples are being stored in Minnesota. A system of blanks, standards and quarter-core duplicates were added to the sample stream by Twin Metals Minnesota LLC to verify accuracy and precision of assay results, supplementing and verifying a variety of internal QA/QC tests performed by ALS Minerals. All data verification and quality assurance/quality control procedures of Twin Metals Minnesota LLC were applied specifically to the results contained in this press release, and the data herein has been verified by Phillip Larson, P. Geo., Senior Geologist with Duluth Metals and a Qualified Person under NI 43-101, in accordance with the procedures of the Company. The data verification procedures and quality assurance/control procedures adopted by the Company and applied to the work being reported in this press release can be found in Section 11 of the "NI 43-101 Technical Report on the Maturi, Birch Lake, and Spruce Road Copper-Nickel-PGE Projects, Ely, Minnesota, USA", with an effective date of June 15, 2012, and dated July 27, 2012. The Technical Report was filed on SEDAR under the Company's profile on July 27, 2012 ( http://www.sedar.com). Dr. Harry Parker, SME, Registered Member, Technical Director of AMEC, is the Independent Qualified Person who prepared the Resource Estimate and is responsible for the mineral resource estimates summarized in this press release. Dr. Parker is a licensed Professional Geologist in the State of Minnesota. Phillip Larson, P. Geo. is the Qualified Person for Duluth Metals and Senior Geologist for Duluth Metals, in accordance with NI 43-101 of the Canadian Securities Administrators, and reviewed and approved the technical content of this press release. About Duluth Metals Limited