In his constant pursuit of the next big diamond discovery, James Campbell, an exploration and mining geologist by profession and MD of dual-listed diamond explorer Botswana Diamonds, has devoted his career to the exploration and development of kimberlites.
Campbell believes that several commercial kimberlites still lie undiscovered below the surface in southern Africa, mainly within the Kaapvaal Craton, which covers a large portion of South Africa, Botswana, Zimbabwe, Lesotho and Swaziland.
This article first appeared in Mining Review Africa Issue 6 2018
He believes that the Kaapvaal Craton is one of the most prospective areas in the world from a geological perspective, a belief he formed based on the more than 31 years of his career spent actively exploring the area.
It is through a combination of deep historical knowledge, innovative exploration techniques and new exploration methods made possible by advanced exploration technology that Campbell believes could lead him and his company to its next big discovery.
He has fully committed himself to this task, having expanded Botswana Diamonds’ exploration drive to not only include Botswana, but also South Africa and Zimbabwe, since taking to the helm as MD in 2016.
Just three months after joining the company, Campbell facilitated the conclusion of an earn-in agreement with private South Africa diamond exploration and development firm Vutomi Mining.
More recently facilitated the signing of a memorandum of understanding with AIM-listed resource development company Vast Resources with the intention to collaborate on developing and exploiting diamond resources in Zimbabwe.
Looking at old deposits through the eyes of new technology
With exposure in the three major countries within the Kaapvaal Craton, Campbell believes that significant exploration potential still exists in South Africa and Botswana owing to a lack of exploration.
In South Africa, even during the “diamond exploration heyday” in the 1980s when the Venetia, Marsfontein, Klipspringer and Oaks mines were discovered, several potential commercial discoveries went undeveloped because the presence of diamonds were not fully understood as a result of the technology and economic climate at that particular time.
Referring to the AK6 discovery in Botswana in 1969, Campbell explains that the diamond potential was not fully understood during initial evaluations which, following re-evaluation of the discovery in the early 2000s, proved to host significant diamond resources and in fact the now famous Karowe diamond mine.
In this case it was the poorly understood impact of diamond breakage that led to the under estimation of the diamond value, explains Campbell, noting that the drilling technology used now is far less destructive than back then.
"Therefore, it is important to note that the relatively high levels of diamond breakage not only cause challenges with the diamond valuation, but also with modelling a production diamond size frequency distribution from the sampling data," Campbell explains.
“If you apply these lessons to our kimberlite mines in South Africa, which haven’t been looked at or evaluated, some of them in more than 50 years, you must at least take the time to evaluate these mines using current technology combined with the innovative thinking we have available to us today,” Campbell emphasises, adding that it is the advent of new technology that could enable a junior miner such as Botswana Diamonds to develop a billion-dollar asset that others have walked away from.
“It is new technology that may enable you to find very different and encouraging results when you revisit previously explored areas using modern, fit-for-purpose technology,” he adds.
Technological breakthrough in progress
In doing so, Campbell has identified an area within the field of geology that requires considerably more work in terms of development – the approach to the large diameter drilling (LDD) of kimberlites.
There have been three generations of this technology, the first was the cable tool or stomper rig, which as the name suggests, broke vast amounts of diamonds and led to a significant under estimation of the diamond deposit.
The second generation of technology, released in the middle to late 1980s was percussion drilling – this produced coarser chips and less diamond breakage but still significant diamond breakage.
Next was the advent of reverse flood rotary drilling – which was developed within De Beers and used on the AK6 discovery in the 2000s and broke significantly less diamonds.
From this point onwards, there has been no significant leap in terms of technology development despite the fact that there are major problems in the interpretation of diamond data from LDD because of the breakage of diamonds.
One of the technologies being investigated by Botswana Diamonds as a means to overcome diamond breakage is direct pipe – a mini tunnel boring technology developed by German tunnel boring machine manufacturer Herrenknecht.
“We are in discussion with Herrenknecht to evaluate the use of this technology for LDD as it has proved to be less destructive than technologies used in the past,” Campbell notes, adding that diamond breakage is one of the key sampling impediments needed to correctly evaluate diamond size frequency distributions within kimberlite samples.
Botswana Diamonds is in the process of conducting a mini study on evaluating the potential of this technology and its cost effectiveness in a kimberlite sampling application, which if proven viable, could mean a massive breakthrough not only for the African junior but also pave the way for innovative diamond exploration and discovery going forward.