Gold Mining : Can the Heavy Machinery do the work in Sudan
The Block 14 mineral exploration project covers an area of 1,000 km2. It is located in the Nubian Desert in the north of the Republic of the Sudan, close to the international border with Egypt. The property is situated 700 km north of the national capital Khartoum and straddles the boundary between the Red Sea and Nile States. The nearest population centre is the town of Abu Hamad, located 180 km due south of the property.
In September 2018, MPR Geological Consultants Pty Ltd (MPR) estimated gold and silver Mineral Resources for the Galat Sufar South and Wadi Doum deposits. MPR estimated recoverable resources by Multiple Indicator Kriging with block support correction to reflect open pit mining selectivity, a method that has been demonstrated to provide reliable estimates of gold and silver resources recoverable by open pit mining for a wide range of mineralization styles. Exploration conducted by Shark on the SMP area has been carried out to industry standards. The exploration strategy implemented by Shark of utilising multiple regional data sets including satellite imagery, airborne geophysics and drainage geochemical surveys combined with geological prospecting has been successful in identifying a number of targets. Shark has discovered gold mineralisation on the Sand Metals Project (SMP) in Block 14 with significant channel sample and trench intervals corroborating continuous chip sampling results at Galat Sufar South. The SMP has had little if any modern exploration carried out in an area covering more than 20,020 km2. Shark considers the Northern Sudan Nubian desert region to be an essentially unexplored new gold province and the intense artisanal mining supports this statement with a purported 20,000 artisanal miners active within the region.
Reconnaissance exploration has been carried out in all of the Exclusive Prospecting Licences (EPL’s) with a focus on Block 14, where within 6 months the exploration team has discovered 3 quality targets areas at Galat Sufar, Mussieye and Big Pits. High resolution WorldView imagery for an area of 500 km2 in Western Gabgaba has proved to be very effective at identifying hard rock artisanal mining with more than 160 discrete operations identified to-date, covering a cumulative area of 1,400 km2 and a programme of field checking all hard rock mining operations is underway. A further 13.5 km2 of artisanal colluvial mining activity has also been defined and a parallel programme of field checking the largest areas of concentrated surface mining has already identified new areas of bed rock gold mineralisation.
Initial grab sampling from Galat Sufar North returned gold grades of 8.1 and 2.3 g/t Au from sericite – carbonate – hematite altered schists. Mapping defined a package of greenschist grade metamorphosed volcano sediments in shallow thrust contact with a post deformational syenite.
A total of 79.9 Mt of crusher feed at a gold grade of 1.11 g/t is contained within nine pits across the two deposits, along with 119.2 Mt of waste, resulting in a strip ratio of 1.49:1.
A combined mining schedule demonstrates that a processing rate of 6.0 Mt can be sustained for 14 years, including an initial ramp up period in Years 1 and Year 2. A pre-production period of six months is utilized to strip waste from both deposits and stockpile minor amounts of crusher feed, ready for the commissioning of the processing plant. The pit at WD is mined for the first five years and blended with material from GSS. An elevated cut off grade over eight years maximises early returns by blending the significantly higher-grade material from the WD deposit and gain access to the higher grades at depth in the Main and East pits. The last six years rehandle the low-grade stockpiles.
Mineral Processing and Recovery Methods
A comprehensive program of metallurgical testwork was conducted at SGS to identify the optimum processing route, generate recovery equations and provide data for plant design. Mineralogy, comminution, leach, carbon modelling, thickening and rheology tests were conducted on a large range of ore lithologies and domains.
The Block 14 ores are amenable to a conventional gold processing scheme incorporating crushing, SAG and ball milling, cyanide leach, carbon adsorption, elution, electrowinning and gold smelting. The comminution circuit and gold recovery plant design is based on a throughput rate of nominally 6.0 Mtpa.
Trade-off studies have identified that there is economic benefit in including a pre-aeration stage ahead of cyanide leaching to reduce cyanide consumption rates and that the Kemix Pumpcell CIP circuit provides the optimum carbon adsorption circuit design.
The proposed process route is a proven and robust concept with very little associated risks, apart from the typical operational hazards stemming from the reagents that are used in the process. The plant design will take cognisance of this fact and good engineering practise and industry standards will be applied to design a safe operating plant.
There are currently no objections to the development of the Project. There are no receptors in the area, with no officially recognised human settlements in proximity. The Project has undertaken an environmental assessment and data collection is continuing. The arid conditions and sparse vegetation of the concession provide a difficult environment, which is primarily nocturnal. The use of remote infrared cameras provides the opportunity to record these nocturnal animals. Other wildlife records are captured through daily observations, to the extent possible. Climate data and weather data has been collected and compared, to provide reliable data for the EIA and design teams. Water data from the existing boreholes and Talat Abda well has been collected and there are no other known sources of potable water and few potential water users who legally reside in the vicinity. Social data continues to be collected, through monitoring of artisanal miner’s activities. All information collected will be used in managing social and environmental impacts associated with the Project.
Based on a gold price of US$1,350 /oz, the Project has a pre-tax IRR of 38.5% and pre-tax NPV5% of US$723M.
The Project has a post-tax IRR of 33.3% and a post-tax NPV5% of US$607M. The Pre-tax undiscounted payback period is 2.5 years and Post-tax, undiscounted payback period i s2.9 years from start of production.
The NPV and IRR are most sensitive to the metal price / recovery, pre-production capital costs and plant and mine operating cost.
Mining and Opportunities
Material haulage from Wadi Doum could be improved if long distance haulage units which can be loaded at the face are utilized. This would negate the need for ROM stockpiles and re-handling of the crusher feed, potentially saving US$0.40 – 0.50 /t of crusher feed from Wadi Doum.
A review of the hydrogeology will lead to a greater understanding of the effects of groundwater on the pit walls (if any) and could allow for further steepening.
One opportunity has the potential to reduce operating costs or improve recovery and will be investigated with additional test work:
• Undertake an economic trade-off / optimization study on increasing silver recoveries by increasing carbon movement.
A Mining Lease is granted upon application by an existing EPL holder, subject to the provision of a feasibility study, a development and operating plan and an environmental management plan.
Under the terms of the concession agreement, after consultation with the MoM, MSMCL shall incorporate a new company for the purpose of holding the issued mining lease. The permit is granted for an initial 30-year period and may be renewed for subsequent 10 year terms until the mining deposits are exhausted.
A Mining Lease will be granted by the Minister of Minerals and gives the holder the exclusive right to explore for and mine mineral deposits within a certain parcel of land for which the permit is granted.
The Mining Lease gives the holder the right to construct mineral processing and support facilities and to operate these facilities to produce saleable mineral products that the permit holder will be entitled to sell on world markets.
Upon grant of the Mining Lease, the permit holder is required to give the Republic of the Sudan an un-dilutable free-carried 20% interest in the company holding the title to the permit.
Exploitation Permits are treated as real property rights with complete right of mortgage and liens. Both exploration and mining permits are transferable rights.
For information on mining permits around Block 15, 68 and others please contact firstname.lastname@example.org