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Message: NI43-101 compliant 2010 Feasibility Study

NI43-101 compliant 2010 Feasibility Study

posted on Feb 11, 2010 07:52PM

February 3, 2010 - American Bonanza Gold Corp. (TSX: BZA) ("Bonanza") is pleased to announce the positive results of its NI43-101 compliant 2010 Feasibility Study (the "Study") at Bonanza's 100% owned Copperstone Gold Mine in Arizona. The Study, prepared by Continental Metallurgical Services under the guidance of Todd Fayram, B.S. Eng, MMSA-QP(M) a Qualified Person under National Instrument 43-101, was prepared to present the results of a comprehensive evaluation of the Copperstone deposit and provide an economic evaluation of future underground mining operations at the past producing Copperstone mine. The Study indicates Copperstone will be a profitable gold mine with positive economics from the re-activation of mining, pursuing the gold mineralization from the past open pit to the future high grade underground mining. Re-activation of mining at Copperstone remains Bonanza's primary objective.

Highlights of the Study

The Copperstone Gold Mine is estimated to 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:

Gold Price Case Gold Price (US$/Oz) IRR (%) Undiscounted pre-tax Cash Flow (US$) Net Cumulative After-Tax Cash Flow (US$) Net Present Value After-Tax (US$) (Discounted)
Very Low $650 17.0% $7,380,073 $7,380,073 $4,488,124
Low $850 74.3% $50,162,532 $47,461,378 $37,194,541
Base Case $962 96.3% $74,169,910 $64,763,463 $51,291,204
Spot $1104 120.5% $104,496,256 $85,434,230 $68,089,302
High $1250 145.1% $135,727,452 $106,035,800 $84,874,376
Very High $1400 170.4% $167,814,296 $126,868,118 $101,878,924


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.

"This Feasibility Study represents another substantial milestone for the Copperstone Mine," said Brian Kirwin, President and CEO of Bonanza. "Copperstone has a very strong economic profile, significant infrastructure on-site, low capital costs, fast capital payback, a rapid permitting timeline, and excellent expansion potential near the proposed mine workings. Bonanza will stay focused on bringing Copperstone into production in 2010, to achieve production during these times of high gold prices."

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):

Net Present Value Base Case: $51 million (USD)
Net Present Value Spot Gold Case: $68 million (USD)
Internal Rate of Return: 96%
Gold Production: 25,000 to 55,000 ounces per year
Mine Life: 6.3 years with expansion potential
Payback Period: 13 months
Capital Cost: $17.74 million (USD), including contingencies, working capital, reclamation bonding, etc.
Total Mined Ounces: 256,431 ounces
Total Gold Recovered: 230,700 ounces
Average Resource Grade (M&I): 0.302 oz per ton, 10.4 grams per tonne
Cash Production Cost: $415 per ounce of gold produced
Total Production Cost: $624 per ounce of gold produced
Permit Timeline Target: July 2010



The Base Case is on an After Tax basis, with future cash flows discounted to present. Key Base Case assumptions for the Study include:

Gold Price: $962 per ounce of gold (USD)
Discount Rate: 5%
Production Rate: 450 tons per day = 157,500 tons per year
Cumulative Mine Production (P&P): 1.0 million tons @ a diluted grade of 0.256 ounces per ton (8.76 grams per tonne) gold
Cash operating costs: $95.64 per ton of ore milled
Mining: $60.64 per ton mined, including development
Processing ore: $21.75 per ton milled
G&A: $13.25 per ton milled
Mining dilution: 10.3% at zero gold grade
Tax Regime U.S. Federal, Arizona State
Gold Recovery: 90%
Cutoff Grade: 0.131 ounces/ton (4.5 grams per tonne gold)


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 will be filed on SEDAR on a timely basis.

Mineral Reserves

Mineral Reserves at Copperstone identified by the Study and used for the economic analysis are developed as of January 29, 2010:

Reserve Classification Tonnes Grade

(g/tonne Gold)

Contained Grams of Gold Contained Ounces

of Gold

Proven Reserves 820,965 9.670 7,939,131 255,253
Probable Reserves 5,285 6.935 36,655 1,178
Dilution 85,217 0 0 0
Proven & Probable 911,367 8.750 7,975,786 256,431


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

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:

Resource Classification Tonnes Grade (g/tonne Gold) Contained Grams of Gold Contained Ounces
of Gold
Measured 933,062 10.37 9,675,742 311,083
Indicated 8,294 7.88 65,334 2,101
Measured & Indicated 941,357 10.35 9,741,086 313,183
Inferred 369,000 12.21 4,506,648 144,892


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

Gold Grade Cutoff (g/t Gold) Tonnes Grade
(g/t Gold)
Contained Grams of Gold Contained Ounces of Gold
1.7 3,111,893 5.31 16,529,074 531,422
5.1 941,357 10.35 9,741,086 313,183
6.9 536,731 13.71 7,358,194 236,572


Inferred Resources at Various Cut-Off Grades

Gold Grade Cutoff (g/t Gold) Tonnes Grade
(g/t Gold)
Contained Grams of Gold Contained Ounces of Gold
1.7 1,762,000 4.70 8,270,949 265,917
5.1 369,000 12.21 4,506,648 144,892
6.9 240,000 15.60 3,750,305 120,575


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:

Resource Classification Tonnes Grade
(g/t Gold)
Contained Ounces of Gold
Measured 10,400 20.9 7,005
Indicated 960,000 10.6 327,924
Measured + Indicated 970,400 10.7 334,929
Additional Inferred 189,600 10.9 66,266


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:

Discount Rate Case Discount Rate (%) IRR (%) Undiscounted pre-tax Income (US$) Net Cumulative After-Tax Cash Flow (US$) Net Present Value After-Tax (US$) (Discounted)
Very Low 0 97.2% $74,169,910 $65,571,347 $64,763,463
Low 3 97.2% $74,169,910 $65,571,347 $58,904,720
Base Case 5 97.2% $74,169,910 $65,571,347 $51,291,204
High 7 97.2% $74,169,910 $65,571,347 $46,878,448
Very High 8 97.2% $74,169,910 $65,571,347 $44,844,903


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.

Processing Plant

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.

Permitting Copperstone

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.

Royalty Structure

The Patch Living Trust ("PLT") represents the Lessor's interest in Copperstone. The lease is for a ten year term, and is perpetually renewable on the existing terms at Bonanza's discretion. The PLT royalty is a net smelter return ("NSR") based on the royalty schedule in the following table. The lease calls for an advanced royalty payment of $30,000 per year which is recoverable from future production royalties. To date, US$420,000 has been prepaid on the future royalties and will be deducted from initial royalty payments.

Royalty Avg. LME Gold Price ($/oz)
1% < $350
2% $350 to $400.99
3% $401 to $450.99
4% $451 to $500.99
5% $501 to $550.99
6% >$551


A NSR royalty is based on the gross revenues received from the production and sale of minerals from the royalty property less all of the charges and expenses paid by Bonanza for the processing, recovery, refining, smelting, freight, taxes and treatment of the minerals produced from the royalty property.

The Centennial Development Company royalty is a 3% NSR royalty which applies only to the first 50,000 tons of mineralized material produced from the royalty property, which is a small portion of the northern end of the proposed mine.

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).

Copperstone Summary

The Copperstone Property is located in western Arizona within the Walker Lane mineral belt where it intersects gold provinces in Southern California and Western Arizona. These provinces host a total known gold endowment of over 40 million ounces of gold. Copperstone is located within a lesser-known, globally significant, high grade gold province.

Between 2002 and 2005 Bonanza completed over 46,400 meters of primarily core drilling, including over 7,000 meters drilled from underground. Underground drilling was accessed from a 600 meter decline completed by Bonanza that accesses high grade gold mineralization north of the open pit. During 2006 Bonanza announced the results of a NI 43-101 compliant study by AMEC International that estimated Measured, Indicated, and Inferred mineral resources. With the addition of a few drill holes, the current updated resources are based on essentially the same data, and are the subject of Bonanza's mine development plans.

During 2007 and 2008, a total of 59 exploration holes were drilled, with a combined length of 17,490 meters (57,374 feet). Several targets returned strong gold anomalies, with the southern margin of the D-Zone, the South Pit zone and the Southwest zone showing the best results to date.

The South Pit Zone, the Southwest Zone, areas down-dip from the main planned mining areas which generally remain open to expansion, and several other earlier stage exploration targets all have the potential to significantly extend the mine life beyond current gold resources and improve overall economic returns. The potential for these gold zones, which lie outside of the current mineral reserves, to extend the mine life at Copperstone will be evaluated as mine development efforts continue.

About Bonanza

Bonanza acquires, explores and develops high-grade gold properties in the United States and Canada. Bonanza is working to re-activate mining at the development-stage Copperstone gold property in Arizona, is well financed and has no long-term debt and no gold hedges. Please visit our website at www.americanbonanza.com

AMERICAN BONANZA GOLD CORP.

Note: All numbers may not add up to total due to rounding errors.

QUALIFIED PERSONS

The technical information in this news release and in Bonanza's associated technical reports was prepared in accordance with the standards of National Instrument 43-101 "Standards of Disclosure for Mineral Projects" ("NI 43-101") and was reviewed by Chris Pratt, Bonanza's Geologist at Copperstone and Qualified Person ("QP") under NI 43-101.

The following persons are responsible for the preparation of the following sections of the Feasibility Study:

Todd Fayram, B.S. Eng, MMSA-QP(M), Project Lead, Metallurgy and Process, Economics, Environmental; Chris Pratt, ASBOG, Geology and History; Jon Brown, M.B.A., C.P.G. and Kim Drossulis, B.S. Eng, (through employment with Telesto Nevada Inc.), Mining and Resource; Chris Fedora, B.S. Eng, (through employment with Vezer Industrial Professionals), Tom Buchholz, B.S. Eng, MMSA-QP(M), (through MarGeo, Inc), Mining and Reserves; Dave Nicholas, M.S. Geo Eng, P. Eng. (through employment with Call & Nicholas, Inc.), Geotechnical. Messrs. Fayram, Buchholz, Pratt, and Brown are Qualified Persons under NI 43-101.

DATA QUALITY ASSURANCE AND QUALITY CONTROL

As previously disclosed, the drill samples at Copperstone were collected by Bonanza personnel at the drill for each drill hole. All of Bonanza's facilities are secure, inside the fenced compound. The core was transported to Bonanza's core processing facility on site at Copperstone by Bonanza personnel.

All core was logged for recovery and other geotechnical features, prior to being sawed lengthwise in half by Bonanza personnel. Individual core samples were selected on a geological basis to characterize the gold mineralization associated with various rock types, alteration types and structural horizons. Subsequent to sawing and sampling, the remaining half core was geologically logged and stored on site as reference samples. The samples were bagged, labeled and tied at the Copperstone project site by Bonanza personnel. Geologic information was recorded on standardized sample description forms which included color, rock type, alteration, mineral species and abundance. Samples are stored in a secure facility at the Copperstone project site.

DATS Trucking, Inc. collected samples from the secure facility at Copperstone and transported the samples to representatives of American Assay Laboratories (AAL) in Sparks, Nevada. There, representatives of American Assay Laboratories (AAL) in Sparks, Nevada received the samples and took custody of the samples. AAL is ISO / IEC 17025 certified and has successfully completed Canadian proficiency testing (CCRMP).

At the AAL laboratory, the core samples were dried, crushed to -10 mesh, pulverized to -150 mesh, split to 1,000 gram pulps, and fire assayed for gold two times using 2-assay ton fire assay charges with a gravimetric finish. Reported gold grades are the average of these two assays for each sample. Samples were routinely assayed in duplicate. There is good correlation between the duplicate assays, and Bonanza's QA/QC program and database integrity have been reviewed by several previous independent studieds, and as part of the current Feasibility Study, where it has been judged appropriate for the uses herein. All samples greater than 0.100 opt, standards, and blanks were routinely submitted to additional labs for verification. Standards were routinely inserted for assay. Check assays were routinely submitted to BSI-Inspectorate, Sparks, NV for an additional 5-assay ton gold analysis. BSI-Inspectorate is ISO 9002 certified. Bonanza personnel delivered the samples to the check lab.

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