Pit Optimisation & Project Design
In May 2018 Cube Consulting re-ran and revised the Hamama West block model, at a cut-off grade of 0.3 g/t gold equivalent, focussing on the oxide and transitional mineralisation types that are the subject of the proposed starter open pit mine project, incorporating the new 2017 diamond drilling and trenching results, as well as a new re-interpretation of the weathering profile at Hamama West completed by Aton’s technical team. Additionally mineralisation at the Crocs Nose Zone was included in the new block model, which had been previously excluded from the 2017 MMRE.
Mining of the gold oxide cap is planned to be undertaken using conventional open pit mining techniques. The open pit will have final dimensions of 700m along strike, up to 200m in width, and will extend to a maximum depth of 60m below ground level. Mining is to be conducted by conventional drill and blast operations for the majority of the excavation, with approximately 15% of the mined volume estimated to be amenable to free-digging.
Cube Consulting also undertook pit optimisation studies of the Hamama West gold oxide cap, based on potential 2, 3, 4 and 5 year life of pit options. The Crocs Nose Zone was excluded from all options. Each option maintained the overall project crusher feed material at a total of 2.6 million tonnes (“Mt”), with treatment rates adjusted accordingly to define the options in terms of years in production. The optimisation parameters for the Hamama West open pit were derived from locally derived Egyptian contractor quotes, first principle engineering, mineral processing testwork and other relevant assumptions based on Cube’s experience. A series of pit shells were generated for each of the four life of pit options, which in turn were used to produce four production schedules for evaluation and selection of the optimum life of pit option. From these the 3 year life of pit was selected as the preferred option for the Hamama West gold oxide cap starter pit.
The selected optimised pit design contains 2.6Mt of mineralised process feed material and 1.7Mt of waste material resulting in a mining strip ratio of 0.66:1. The designed waste dump is located in a flat lying area of ground immediately to the northwest of the open pit.
The preferred site for the HLF, located in a wide flat-lying area in Wadi Um Salamat approximately 3km to the west of the proposed open pit mine, was selected on the basis of a number of technical and economic factors. The geotechnical studies have indicated that the preferred site is suitable and appropriate. The HLF will be approximately 400m x 500m in size, and will consist of three 8m lifts.
Mine ancillary buildings and maintenance facilities will be located in the area between the open pit and the HLF. Upgrading of the existing haul road between the open pit and the HLF site will be required, as will the site roads around the wadi area of the HLF and offices. The roads will be constructed for frequent traffic by light and medium sized haulage vehicles.
The design and economic analysis of the Hamama West gold oxide cap starter open pit project is based on the following mining and processing parameters: modelled metals prices of $1,350/oz gold and $17.00/oz silver; 74% Au and 40% Ag oxide process recovery; 71% Au and 34% Ag transitional process recovery; 365 production days per year; 0.83Mtpa annual production rate; a one year pre-production period; 3 year open pit life.
The mining plan has scheduled 2.6Mt of run-of-mine mineralised material and 1.7Mt tonnes of waste to be mined at a strip ratio 0.66:1 from a contractor operated open pit, and processed through a traditional HLF to recover 52,600oz of gold and 855,000oz of silver, over the 3 year life of the starter open pit.