Application of surpac software in open pit

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The Maxbo Mining Company (a hypothetical mining company) has through extensive exploration, discovered a near surface lode gold deposit of commercial value at Tarkwa in the Western Region of Ghana and intends to exploit this deposit using surface mining technology. The immediate concern of the company is to design a preliminary pit so that an idea about its depth, slope, lateral extent, stripping ratio and the average grade can be obtained. The huge amount of exploration data requires that some appropriate computer software must be employed to speed up the work and also avoid human errors usually associated with manual methods of pit design. In this thesis report, an interactive computer-aided approach within the framework of the Surpac Software is used to model the deposit and design a suitable pit for the exploitation of the deposit. Initially, field data was collated and validated, drillhole plans and sections were produced, and with a constraining cut-off grade of 1.0 g/t, the outlines of mineralised zones on the various sections were digitised, this formed the framework around which the orebody model was built by the process of stitching. The designing work involved digitising the orebody outlines at various depths of the deposit, and by specifying the desired bench height, berm width, ramp width and gradient, a possible pit design layout was generated from bottom upwards until the surface was intersected. The final pit has a depth of 70 m, slope angle of 30°, lateral extent of 300 m, and an overall stripping ratio of 8.4. The tonnage of ore to be mined is approximately 189 097 t with an average grade of 5.0 g/t. It has been recommended that the final pit should be optimised to obtain an ultimate pit, which will be most economic for exploitation of the deposit.
A thesis submitted to the Board of Postgraduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirement for the award of the Degree of Master of Science in Mining Engineering, 1998