The Copperstone Gold Mine is estimated it will produce on average 45,891 ounces of gold annually for the first 3 years, and have a capital investment payback period of only 13 months. The Study details a total capital cost of US$17.74 million, including working capital, G&A startup, reclamation bonding, and contingencies. The Study estimates the cash production cost to be US$415 per ounce of gold produced.
The After Tax Net Present Value ("AT-NPV") of the mine is US$51,291,204 and the Internal Rate of Return ("IRR") is 96.3% in the base case using a future gold price estimate of $962 per ounce and a 5% discount rate. Using the current spot gold price ($1104 per ounce on www.kitco.com on December 28, 2009) the AT-NPV rises to $68,089,302 and the IRR increases to 120.5%. The table below provides a range of economic results at various gold price assumptions.
Copperstone Economic Sensitivities at various Gold Prices:
The Study results indicate a total of 256,430 ounces of gold can be mined from current known diluted Proven and Probable Mineral Reserves during the 6.3 year mine life at Copperstone. The Study also indicates a cash production cost of $415 per ounce of gold. Bonanza plans to continue the rapidly progressing permitting process, and move Copperstone to production during 2010.
The Study supports a trackless underground mining operation, delivering ore to an on-site crushing, grinding, gravity concentration and finally flotation concentration of the gold bearing ore. The flotation concentrate will be shipped off-site to a gold recovery plant in the southwestern United States. The mine and recovery plant have been designed to reduce capital costs and speed permitting timelines while maintaining high rates of return.
Highlights of results from the Study include (results shown are for the Base Case, except the Spot Gold price case which uses Spot gold price of $1104 as discussed above):
The Base Case is on an After Tax basis, with future cash flows discounted to present. Key Base Case assumptions for the Study include:
This financial analysis has been estimated based on the diluted Proven and Probable Mineral Reserves which are derived from only the Measured and Indicated Mineral Resources. The cost estimates are based on contract mining and processing of the flotation concentrates at off-site processing facilities located in the southwestern United States. The Study report and associated documentation are filed on SEDAR.
These Mineral Reserves at Copperstone were calculated by Chris Fedora, under the supervision of Tom Buchholz, B.S. Eng, MMSA-QPM under NI43-101, both acting through Vezer's Industrial Professionals, an independent consulting firm contracted by Bonanza to perform underground mine design, stope planning, mine scheduling, and calculate mineral reserves. Reserves were calculated using the Key Base Case assumptions set out above.
These Mineral Reserves are based on a Resource cutoff grade of 4.5 g/tonne gold, and capped at 171 g/tonne gold. The mine has been designed primarily as a trackless drift and fill mining operation, with ramp access and paste backfilling. Mining dilution across the life of the project is estimated at 10.3%. Pre-production development and mining of gold bearing Reserves are planned to begin in the D-Zone, north of the existing open pit, where Bonanza has exposed Proven Mineral Reserves in a tunnel driven from the north end of the open pit. Truck haulage is planned for transporting the ore from the underground mine to the surface processing facility.
Mineral Resources identified at Copperstone and included in the Study (which include the Mineral Reserves set out above) are set out in the below table:
These Mineral Resources at Copperstone were calculated as of January 29, 2010 by Telesto Nevada Inc.; the QP under NI43-101 is Jon Brown, M.B.A., C.P.G., who is in the employ of Telesto Nevada Inc. Telesto is an independent consulting firm contracted by Bonanza to perform such activities. These Mineral Resources are based on a cutoff grade of 5.1 g/t gold, and capped at 171 g/t gold.
Resource calculation methods differ between the current Resources and the 2006 Resources in that the current Resources contain a small number of new drill holes, and utilize smaller resource blocks (5'x5'x3') which should better model the mineral deposit compared to the 2006 Resources which used larger blocks (18'x12'x6'), and the current Resources utilize a more conservative interpolation method (Inverse Distance Cubed) compared to the 2006 Resources which were kriged.
Mineral Resource Cutoff Grade Analysis
The Study also examined the Measured, Indicated Mineral and Inferred Resources at various gold cutoff grades, which are set out in the below tables:
Measured and Indicated Resources at Various Cut-Off Grades
Inferred Resources at Various Cut-Off Grades
This cutoff grade analysis indicates that a significant portion of the Resources are available for mining at higher cutoff grades, which suggests resiliency with respect to gold price risk.
Previous NI 43-101 compliant Mineral Resources
As previously announced, the current Coppperstone Mineral Resources are an update to the Mineral Resources estimated, effective January, 2006, by AMEC E&C Services, an independent, respected international mining engineering firm, under contract with Bonanza. The 2006 Mineral Resource estimates were based on a cutoff grade of 5.1 g/t gold, with gold assay grades capped at 137 g/t gold and are presented for comparison purposes in the following table:
These Mineral Resources can be compared to the January 2006 NI43-101 compliant Mineral Resources shown below in the "Previous NI 43-101 Compliant Mineral Resources" section. The current Resources show a significant increase in ounces of gold contained in Measured Resources from 7,005 ounces to 311,183 ounces of gold, and a corresponding reduction (327,924 ounces compared to current 2,101 ounces) of gold in Indicated Resources as material is converted from Indicated Resources to the Measured Resources category.
The results of the Study also demonstrate a significant increase in ounces of gold contained in Inferred Resources, from 66,266 ounces previously to a current 144,892 ounces. The previous Inferred Resources were located at several locations around the property and included little or no mineralization from the South Pit Target, which was discovered and drilled subsequent to the 2006 Resource calculations. In the current Study, the Inferred Resources are all located in the South Pit Target, which will be further explored as exciting potential for expansion of the Mine.
Copperstone Economic Sensitivities at various discount rates:
These economic results using various discount rates to discount the value of future cash flows from mining operations were calculated using the Key Base Case assumptions set out above, with the only variable being the discount rate. While in the current economic environment the risk free rate of return on capital is near 2%, and the site location in Arizona generally would not attract an increase in the discount rate to reflect country risk, the Study uses 5% to maintain the conservative nature of the estimates.
The Study compiles and reviews the detailed metallurgical testing that has been completed, in order to select an appropriate processing method and to optimize process operating parameters. Samples of various ore types and grades have been prepared and sent to various laboratories and testing facilities for metallurgical testing. These laboratories include: Hazen Research--1986--Cyanide Leaching; Hazen Research--1986--Mineralogy; Cyprus Metallurgy--1986-Phase I to III--Cyanidation and Flotation; Resource Development Inc.--1999--Cyanide Leaching; McClelland Laboratories--2000--Cyanidation, Gravity and Flotation; Echo Bay Minerals--2001--Flotation; McClelland Laboratories--2005--Cyanidation, Gravity, Flotation; CAMP--2009--Gravity and Flotation. The testing consisted of cyanidation studies including bottle roll and column leach tests, gravity concentration tests, flotation studies including flotation only and flotation tests followed by cyanidation, and reagent consumption tests.
Metallurgical test work supports gold recoveries of 90% utilizing a process which involves crushing, grinding, gravity gold recovery, and floating a gold concentrate followed by offsite recovery of gold from the concentrate. This is the circuit designed for the Study.
The results indicate that the gravity recoverable gold potential in the 2009 composite samples appears very good at about 25-40% at typical weight recoveries (1.0% to 1.25%) used to produce a salable material with a gold content from 8 to 15 ounces of gold per ton. Bulk gold flotation recoveries are reasonable and at a grind of 200 mesh with direct flotation recoveries of about 70 to 75% are indicated and when combined with gravity, 86 to 94% recoveries are achievable
In November 2009, another milestone on the road to mine development was met, as the Copperstone Mine Plan of Operations was accepted as complete by the United States Department of the Interior's Bureau of Land Management ("BLM"). The BLM is the lead governmental agency with oversight of Bonanza's mining operations.
Permit applications are currently being prepared for submission to the Arizona Department of Environmental Quality, the Arizona Department of Water Resources, the US BLM (additional submissions), local governmental authorities, the US Environmental Protection Agency, and other regulatory agencies. Schlumberger Water Management Consultants is an industry-leading environmental and engineering consulting firm and is Bonanza's lead permit coordinator for Copperstone, and is also providing tailing site facility design and hydrological planning for the mine development.
The Copperstone site has substantial mine development advantages which could result in a shorter than typical mine permitting process and reduce the capital cost for the new underground mine. Copperstone is a modern previously mined site with a clean, non-sulfide bearing mineral resource, and the current mine plan calls for no additional disturbance to the public lands. The mine plan has been designed to have a very low environmental impact, and this design could contribute to a permitting process that is more rapid than is typical for new mine development.
Capital Cost Estimates
The Study results estimate a total Capital Cost of $17.74 million. This includes direct costs for procurement and construction totaling $9.8 million, which includes the processing plant, including purchase and installation of the crushing and grinding circuits, the gravity and flotation recovery circuits, and buildings, communications, etc with an estimated cost of $5.2 million, and direct costs also include $2.7 million for pre-production underground mine development, and lastly, direct costs include $1.7 million for tailings management and reclaim systems. Indirect costs included in the Capital Cost estimate are: $2.9 million for working capital, $1.1 million for reclamation bonding, $0.4 million for owner's costs, $2.3 million for other indirect costs, and finally, a contingency budget of $1.3 million.
Ongoing capital required for further tailings impoundment expansion, bonding, reclamation, and demobilization of the contractor are estimated at $1.6 million. These costs are budgeted to be derived from operating cash flow after mine operations have commenced.
The Capital Cost estimates in the Study report represent a total estimated preproduction cost to design, procure, construct, and commission the various facilities described in this study to bring the Copperstone Mine back into gold production. According to the authors of the report, the estimate is categorized as Feasibility level with an expected accuracy range of ±7.5% at the bottom line. All costs are expressed in first quarter 2009 US dollars, with no allowance for escalation or interest during construction. The estimate covers the direct field costs of completing the project, plus the indirect costs associated with design, construction and commissioning of the facilities.
The Copperstone Mine produced nearly one-half million ounces of gold between 1987 and 1993 through open pit mining. Existing infrastructure which remains from this time or which has been subsequently installed by Bonanza is considerable, and serves to reduce the current capital requirements for the mine. Existing infrastructure includes a 69 KV power line and substation and three water wells, all sufficient for the new mine at Copperstone. Additional infrastructure on site includes offices, maintenance shops and a laboratory building. High grade gold mineralization in the D-Zone that is scheduled for Year One mining production has already been accessed in a 600 meter long underground tunnel driven by Bonanza.
Operating Cost Estimates
The Study results estimate a total Mine Operating Cost of US$95.64 per ton of ore processed. This includes a mining cost of US$60.64 per ton of ore and waste mined, a gold recovery cost of US$21.75 per ton of ore processed, and US$13.25 per ton of ore processed for G&A and corporate costs.
The Mine Operating Cost estimates in the Study report represent the total estimated mining and gold production costs, and total corporate costs to accomplish gold production as designed in the new underground mine planned at Copperstone. According to the authors of the report, the estimate is categorized as Feasibility level with an expected accuracy range of ±7.5% at the bottom line. All costs are expressed in first quarter 2009 US dollars. The estimate covers the costs of mining, processing and administering operations to produce gold. Stated another way, the cash production cost of producing one ounce of gold at Copperstone is calculated in the Study results to be US$415 per ounce of gold produced. The total production cost of producing one ounce of gold at Copperstone is similarly calculated to be US$624 per ounce of gold produced.
The Copperstone Development Team
Along with Bonanza's personnel, Bonanza has assembled a team of industry-leading mining and environmental consulting firms to expedite the mine development and permitting process; all are underway and making good progress. Included are: Schlumberger Water Management Consultants (lead permit coordinator, tailing site facility design, hydrological planning), Call & Nicholas International Geotechnical Consultants (geomechanical studies for underground mining and backfilling), Vezer's Industrial Professionals (underground mine design, stope planning, mine scheduling, mineral reserves), Telesto Nevada Inc. (mineral resources), and Continental Metallurgical Services (feasibility report, metallurgical study, mill design, economics, construction scheduling).
Technical information regarding the Copperstone project required to be disclosed under NI 43-101 can be found in the Study. Information regarding risks and uncertainties relating to the Copperstone project development can be found in our annual information form, filed on SEDAR, and specific risks related to the results of the Study can be found in our news release dated February 3, 2010, also available on SEDAR.
The resource estimate was prepared by Jonathan Brown., M.B.A., C.P.G., a qualified person. The reserve estimate was prepared by Tom Buchholz, B.S. Eng - MMSA QPM, a qualified person. The estimates are effective as of February 2, 2010. Details of the key assumptions, parameters, and methods used to estimate the mineral reserves and resources, and information regarding the extent to which the mineral resources and reserves may be materially affected by environmental, permitting, legal, title, taxation, socio-political, marketing or other relevant issues is contained in a technical report entitled "NI 43-101 Technical Feasibility Report Copperstone Project, La Paz County, Arizona" effective February 2, 2010 and revised January 10, 2011, prepared for American Bonanza Gold Corp. by Dr. Corby Anders, Allihies Inc., MMSA QP, C. Eng FlChemE, Tom Buchholz, BS Eng. MMSA, Chris Pratt, LPG and Jonathan Brown, M.B.A., C.P.G.. To review this report in its entirety, follow this link. Mineral resources that are not mineral reserves to not have demonstrated economic viabililty.
©2006 American Bonanza Gold Corporation All Rights Reserved. | Cautionary Notes