Technical Report for the First Disclosure of a Mineral Reserve Estimate for a Material Property
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Technical Report for the First Disclosure of a Mineral Reserve Estimate for a Material Property Wassa Mine, South West Ghana prepared for Golden Star Resources Ltd. Denver, Colorado submitted by David Alexander C.Eng Bogoso Gold Limited Bogoso, Ghana 1st August 2003 Report No. 010803/DA TABLE OF CONTENTS 1 Summary .............................................................................................................................................1 2 Introduction and Terms of Reference.............................................................................................3 3 Disclaimer............................................................................................................................................4 4 Property Description and Location.................................................................................................4 5 Accessibility, Climate, Local Resources, Infrastructure and Physiography ............................6 6 History .................................................................................................................................................6 7 Geological Setting...............................................................................................................................7 7.1 Deposit Type................................................................................................................................12 7.2 Stratigraphy.................................................................................................................................12 7.3 Alteration.....................................................................................................................................13 7.4 Structural Geology......................................................................................................................13 7.5 Mineralization.............................................................................................................................14 8 Exploration........................................................................................................................................16 8.1 Drilling ........................................................................................................................................16 8.2 Sampling Method and Approach ...............................................................................................18 8.3 Sample Preparation, Analyses and Security.............................................................................19 8.4 Data Verification ........................................................................................................................21 9 Mineral Resource and Reserve Estimates....................................................................................22 9.1 Mineral Resource Estimate........................................................................................................22 9.2 Resource Estimation Parameters...............................................................................................24 9.3 Mineral Reserve Estimate ..........................................................................................................32 9.4 Evaluation of Optimum Pit Shell...............................................................................................36 9.5 Mine Design ................................................................................................................................36 9.6 Mineral Reserves ........................................................................................................................38 10 Mining Operations.........................................................................................................................39 10.1 Mining Operations....................................................................................................................39 Report No. 010803/DA 1st August 2003 10.2 Production Schedule.................................................................................................................40 11 Mineral Processing and Metallurgical Testwork......................................................................42 11.1 Metallurgical Testwork ............................................................................................................42 11.2 Process Plant Design ...............................................................................................................46 11.3 Processing Operations .............................................................................................................51 12 Infrastructure .................................................................................................................................52 12.1 Tailings Storage Facility..........................................................................................................52 12.2 Power Supply ............................................................................................................................53 12.3 Existing Infrastructure .............................................................................................................54 13 Environmental................................................................................................................................55 14 Economic Analysis .........................................................................................................................57 14.1 Capital Cost Estimates.............................................................................................................57 14.2 Operating Cost Estimates ........................................................................................................59 14.3 Taxes and other payments........................................................................................................60 14.4 Economic Analysis....................................................................................................................61 14.5 Mine Life ...................................................................................................................................64 15 Interpretations and Conclusions .................................................................................................65 16 Recommendations..........................................................................................................................65 17 References .......................................................................................................................................66 18 Plans.................................................................................................................................................67 19 Date...................................................................................................................................................67 Report No. 010803/DA 1st August 2003 Golden Star Resources Page 1 of 67 Technical Report for the First Disclosure of a Mineral Reserve Estimate for a Material Property Wassa Mine, South West Ghana 1 Summary The Wassa mine, located in the Western Region of Ghana, is an open pit gold mining operation that started production in 1998. It is situated in an area of historic small scale mining, while large scale commercial operations started with the formation of a joint venture between the Mining Lease holders, Wassa Mineral Resources Limited, and the Irish companies Glencar Exploration Limited and Moydow Limited. The joint venture company, named Satellite Goldfields Limited (“SGL”), started an exploration drive across the Wassa Property in 1993, which culminated in a positive Feasibility Study completed in early 1998. Proven and Probable Mineral Reserves were estimated at 17.6 million tonnes at a grade of 1.7 g/t, with a contained gold content of 932,000 ounces. The study envisaged a 3 million tonne per annum heap leach operation, with annual production of around 100,000 oz over a 7 year mine life. Debt financing of $42.5 million was arranged through Standard Bank London Limited and the Commonwealth Development Corporation. Operations started in late 1998, but it soon became apparent that the gold recoveries predicted in the feasibility study could not be achieved. SGL tried and experimented with numerous methods to improve recoveries from the heap leach pads, but were unable to raise production to economically viable levels. In mid-2001, the secured senior creditors exercised security over the project, and put it up for sale. At this stage, a total of 8.33 million tonnes of ore had been mined, with a contained gold content of 444,000 ounces. Golden Star Resources Ltd. (“GSR”), amongst others, carried out a due diligence on the property, which included a preliminary drilling program to test the quoted resources. In late 2002, a final agreement was negotiated with Standard Bank to acquire the assets of SGL, which included the mining lease and all infrastructure. GSR immediately commenced an intensive exploration program, for the purposes of extending the resource, as well as obtaining representative samples for metallurgical testwork. In total, the GSR exploration program has drilled 41,071 meters, comprising 9,356m of diamond drilling, 25,360m of reverse circulation drilling, and 6,355m of reverse circulation drilling on the heap leach pads. Consultants Steffen Robertson and Kirsten were retained to carry out the geostatistical evaluation and resource estimation