With Ghana’s Parliament recently ratifying the regulatory and fiscal agreements for the redevelopment of AngloGold Ashanti’s Obuasi gold mine, the perceptions of Ghana’s mining industry are improving.
"This reinforces our strategy of rapidly advancing our Akrokerri-Homase (AKHM) gold project and achieving production within two years," says Goldstone Resources CEO, Emma Priestley.
This article first appeared in Mining Review Africa Issue 9 2018
“It is the company's intention to build a portfolio of high-quality gold projects in Ghana, with a particular focus on the highly prospective Ashanti Gold Belt,” notes Priestley.
Goldstone is focused on developing the AKHM project, which hosts a JORC Code- compliant 602 000 oz gold resource at an average grade of 1.77 g/t, along strike from the Obuasi gold mine, one of the world's major gold mines with a total historical and current resource in excess of 70 Moz of gold.
Priestley comments that the project hosts two former mines, the Akrokerri Ashanti mine, which produced 75 000 oz gold at 24 g/t in the early 1900s, and the Homase Pit which AngloGold Ashanti developed in 2002/03 producing 52 000 oz gold at 2.5 g/t recovered.
The rationale behind the development of AKHM centres around the area’s potential in light of its proximity to the Obuasi deposit and existing infrastructure.
“The Homase-Akrokeri project and all associated targets are considered ‘Brownfields’ exploration projects.
"The close proximity of the Homase-Akrokeri project area to the modern mining town of Obuasi will simplify the sourcing of the required exploration and mining skills, as well as the equipment needed to advance this exploration property.”
Goldstones’ drilling programme has confirmed that high grade mineralisation under the pit extends down dip, below 200 m and remains open at depth and along strike.
To date 51 drill holes, totalling 14 376 m, have been completed by Goldstone in the Homase-Akrokeri project area.
Priestley illustrates that all holes targeted as direct extensions of the Homase-Akrokeri gold resource intersected the mineralised unit, demonstrating the consistency of the mineralisation trend over a significant strike length and at depth.
“We are confident that with further exploration further potential can be realised,” she adds.
Goldstone’s current activities at AKHM includes accessing the historic high-grade Akrokeri underground gold mine to enable the company to complete a geological assessment of the mine.
It will also allow Goldstone to extract samples as part of it bulk test-work programme.
Access to the old mine workings will, depending on the ground conditions, also enable Goldstone to carry out geological mapping and to investigate potential ore that was not exploited by historic miners.
Priestley notes that it is often the case that in historic underground mining, considerable amounts of ore were often left behind, both in-situ and also from spillage.
“The Akrokeri mine is particularly interesting in this regard, due to the fact that the mine was abruptly closed following ingress of water - meaning that a mine clean-up was, in all likelihood, never executed,” she explains.
She adds that on that basis and assuming the gold recovery from previous workings was not 100%, the board believes that the head grade at the mine could be even greater than 24 g/t gold.
Priestley explains that the company is currently accessing the old Akrokeri Mine via an exploratory shaft, measuring 3 m by 3 m, to approximately 30 m below surface.
Timber sets are being installed in the side walls of the shaft and the shaft is being partitioned to create three compartments, the manway compartment, the services compartment and the hoisting compartment.
“Once the shaft is at 30 m depth below surface, a cross-cut will be developed to gain access to the historic mineralised area whilst at the same time, we will probe for any old workings/voids that may allow the safe access to the old mine workings,” she continues.
Further, she mentions that the Norton Shaft is being explored approximately 40 m to the east of the existing derelict North Shaft.
Work at the old North Shaft is currently underway to ascertain if this shaft can be re-opened for use by Goldstone.
Depending on the state of the shaft, it may be utilised as a second point of egress, for ventilation purposes and also to gain access to the old underground mine workings.
Goldstone has initiated a scoping study to strategically locate material to produce a sample for a bulk test-work programme.
This is an important step in the company’s aim of achieving production within two years as it will assist determine the optimum recovery process for AKHM, combining both gold recovery and cost effectiveness
“It is the company’s intention, once the Akrokeri mine has been accessed, to also accumulate a bulk sample from the underground deposit for the test work programme.
Once the deposit is accessed the size of the bulk sample will be determined,” she explains.
Update on recently launched initiatives
Priestley mentions that with AngloGold Ashanti working on the redevelopment of Obuasi mine it is important for Goldstone to ensure that its operations have a similar effect in the area by contributing to the community and the economy while boosting sustainable development.
“Goldstone has initiated a policy for the schools within the concession area, with three strategic goals; providing potable water, proper sanitary facilities and assistance with education.
"In addition, we have held meetings with the local authorities and have commenced a programme to seek skilled and unskilled labour and employ local people as part of this scheme,” she concludes.