Technical Corner - Enduring the Challenge of Mining in Africa - Created: 06 July 2018 - by G.C. More O’Ferrall - sanire.co.za
Greater levels of rain in Africa, which Africans amusingly call 'the wet season', is not an insignificant part of the increased copper mining cost there.
A generation ago when Africans were more eager, it's said it didn't rain in Africa.
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Introduction I find the title of this article rather apt, as mining in Africa has had, and will still have, many challenges – political, logistical, technical (skills and technology), communal, environmental, etc. Each of these could very easily form separate, lengthy articles/publications; however, this article very vaguely hints on a few of these. From a personal perspective, me being an African, I commenced my career on Vaal Reefs Gold Mine (in Orkney), then moved to Lonmin Platinum (Marikana) before going into the mining consulting industry with SRK (Johannesburg), TetraTech Wardrop, AMEC and AMC in Vancouver (Canada). I have now worked for First Quantum Minerals Limited’s Zambian operations in the North-West province of Zambia for the past 15 months (although still residing in Vancouver). Hence the title, (Still) Enduring the Challenge of Mining in Africa.
From experience gained during my North American consulting travels, the challenges of mining in Africa are not unique to this continent, although what is noticeably disconcerting is my current perception of the South African mining industry, based on media reports and verbal communications with friends/ex-colleagues still working in the South African mining industry. One of the major disappointments to me is the perceived (perhaps misperceived) demise of technical skills transfer. I was fortunate enough to have received excellent training (both in technical and people management) while working for Anglo American – training that I believe has put me in good stead to face almost all of the challenges that I have had to face during my 22 years in Rock Mechanics (technically and dealing with difficult personalities).
I was fortunate enough to have been invited/included in a pillar design group studying pillar performance in platinum mines, and at a recent meeting, I was reminded that we are now the “old guard”, with very few of the extremely experienced (not only number of years in the industry, but particularly various experiences) persons still practising and mentoring upcoming rock engineering practitioners. Every effort should be made by these persons to transfer their knowledge and experience before they leave the industry due to retirement, downsizing, etc., and by the upcoming rock engineering practitioners to make the effort to approach these persons and gain as much information from them in the few years that they may still be employed in the mining industry. If they do not do this, like previous generations, the “younger generation” will also be reinventing the wheel without have an extensive understanding of the fundamentals of Rock Mechanics. Okay, now that I can let go of that “Chinese Lantern”, Francois, and I’ll continue with this article on my latest growth in knowledge and adventure – copper mining in Zambia.
Background During my employment with AMC Consultants in Vancouver, I was requested by an ex-Lonmin Geology colleague, Louis van Heerden, to provide mentoring to the Geotechnical Section at First Quantum Minerals Limited’s Zambian Operations. The contract with them had me doing six, 1-week training sessions, which included tailings and earthen dam embankment inspections, flying from Canada to Zambia for a week, then returning to Vancouver for three weeks and then starting the trip all over again for six different site visits. During the last site visit, I was asked to consider full-time employment, which was most welcome as the mining consulting industry was going through a rather rough patch with the downturn in commodity prices. I commenced working as a full-time employee of First Quantum Minerals Limited’s (FQML) Zambian operations in March 2017.
FQML Zambian Operations FQML currently has two operating surface mines in Zambia, the more mature of the two being Kansanshi Mine, located approximately 10 km outside of the capital of the North-West province of Zambia, Solwezi, and the other, Sentinel Mine, is located in the Kalumbila district, approximately 150 km west of Solwezi (Figure 1). Barrick has a surface mining operation, Lumwana, located midway between these two sites, with the closest town to their operations being Manyama.
Figure 1: Locality map of FQML’s Zambian surface mines in relation to the Copper-
Mining under the ownership of FQML at Kansanshi Mine began in 2005. The main product of the mine is copper (in excess of 240 kt/annum), with gold (~140k ounces per annum) being a by-product. Production at Sentinel Mine is still in the ramp-up stage, with sustainable full production hopefully being reached during 2019 (planned annual ore throughput of 55 m tonnes). Sentinel Mine is one of three resource targets forming the Trident Project, the other two being Intrepid Mine (a granite quarry) and Enterprise Mine (a nickel resource).
Kansanshi Mine This is the larger of the two mines, having commenced operations in 2005. There are two operating surface mines, Main Pit and North-West Pit, with another resource target to the south-east of Main Pit, SE Dome (Figure 2).
Figure 2: Aerial view of Kansanshi Mine’s operating pits and future resource target.
NW Pit (Figure 3) has reached the final depth (120 m below topography) and is expanding laterally, while Main Pit, at approximately 200 metres below topography, is only half its currently planned mining depth. The two pits will hole into each other during 2019. Mineralisation at this mine is associated with steep-dipping quartz veins.
Figure 3: Panoramic view of NW Pit (31 October 2017).
Rock/Geotechnical Engineering functions The rock engineering team on this operation comprises six staff members, some with tertiary education and others without, while all have school-leaving (grade 12) certificates [the literacy level in Zambia is extremely low; government publications reports this as 55.3%]. To improve on this, FQML has built numerous schools in the North-West Province, including a teacher’s training college in Solwezi to ensure that the standard of teachers in the schools is up-lifted.
Some of the rock engineering staff members are in the process of working towards obtaining their Chamber of Mines (CoM) of South Africa’s Strata Control Certificate; one staff member who was transferred to our Panama operation last year has only recently obtained his CoM Rock Mechanics Practitioner’s Certificate.
Besides conducting daily bench-scale stability analyses, the function of the rock engineering team is being focussed purely on rock engineering issues. The team used to do pre- and post-blast inspections to identify and report blast-induced damaged to the bench face; inspect waste dumps and tailings storage facilities (slimes dams) for signs of insta-bility, and got involved in reconstruction of crusher foundations (Figure 4); and provide remedial action recommendations to stabilise tailings and earthen dam embankments, etc. Soil mechanics training has been provided to the team to facilitate their understanding of soil (saprolite) bench design and performance assessment.
Figure 4: Reconstruction of crusher retaining embankment.
Figure 5: Tailings Storage Facility embankment issue.
General stability challenges Rock engineering challenges that are being faced with this mine are mainly related to geologic structure, and drill-ing and blasting practices. Two large multi-bench wedge and/or saprolite sloughing failures have occurred in Main Pit and remedial actions to mitigate the increased footprint of these failures appear to have been successful. At the NW Pit, being the shallower of the two, instability is predominantly associated with surface water management, as erosion channels form in saprolite benches and along deeply weathered fault zones.
Figure 6: Instabilities experienced in the two pits.
Stability monitoring Monitoring at KMP is done both visually and by making use of geodetic instruments, including a total station and prisms (not GeoMos – which is a brand name for Leica’s monitoring solution, including their hard- and software; included here as it was in the most recent SCO theory certificate!), as well as two slope monitoring radars. Occa-sionally, crackmeters may be installed across tension cracks observed in potentially problematic areas. A decline shaft has been developed for wall dewatering purposes and is connected to a vertical raisebored shaft to pump ground water from an underground dam to the processing plant. Visual monitoring of the decline shaft will only be possible once blasted rock has been removed from the portal entrance.
Figure 7: Radar monitoring of Main Pit.
Life in Solwezi Expatriates working for Kansanshi Mining Plc (KMP) generally live on the Kansanshi Golf Estate (KGE), which is locat-ed approximately 5 km outside of the mine gate. As with many mining projects in Africa, as soon as an operation commences, there is an influx of native citizens (sometimes with illegal immigrants interspersed within the initially informal housing complexes) seeking employment, leading to the development of towns and increases in the local population. When KGE was developed, it was then located at a fair distance from the centre of Solwezi. Over the past 10 years, it has slowly been absorbed into greater Solwezi and is now completely surrounded by houses and commercial entities.
Those expatriates who choose to live within greater Solwezi rent their accommodation. With rental properties being scarce to find, it is reported that the rents charged to expatriates are similar to those in certain suburbs/areas of Lon-don, United Kingdom.
FQML has invested heavily in conservation projects, one of which includes introducing native wildlife back into the province. On the golf estate, there are currently sable, impala, puku and oribi antelope, and no day that goes by with-out a KGE resident not seeing at least three of the four species walking past their house. Game has also been intro-duced into the game reserve, which comprises the bush around and between the mining infrastructure within the fenced mining lease area. Some additional species include bushbuck, eland, kudu, zebra and giraffe. There are mountain bike routes within the game reserve and a single one within KGE, and large sporting events are regularly held on KGE (including a couple of mountain bike races, a sprint-distance triathlon, road bike events, limited-overs night crick-et, fun grass bowls events, and golf championships/tournaments) and cater for all ages and abilities of athletes (or po-tential/wannabe athletes).
Other activities include gym work, spinning, yoga, aerobics, swimming (there is a 25-metre-long swimming pool on KGE), fishing (there are two small dams on KGE and a larger one on the mine site), running, soccer, and field hockey (the primary school on KGE has a small soccer and grass hockey field). So, where is the time to work?
Sentinel mine This operation was officially opened in August 2015 and is still busy ramping up to full production. Needless to say, as with most other mining operations/projects, “teething” issues are being experienced and dealt with on a seemingly constant basis. These issues are not easily dealt with during the rainy/wet season, which commences around September and ends at the end of February the following year, as these issues are mostly associated with saprolite benches. Mineralisation at this mine is associated with a lithologic layer, as opposed to veins.
The mine is currently approximately 100 m deep and will possibly reach a depth of approximately 200 m. The width is in excess of 1000 m and the current length is approximately 1500 m, extending to approximately 8000 m.
Aerial photograph of Sentinel Mine.
As with KMP, the focus of the rock engineering team function has slowly been redirected. There are currently four persons in the team providing a rock engineering service to this operation, including Intrepid and Enterprise Mines. No member of this team has yet attempted any of the two parts of the SCO certificate; however, with three of them being graduate mining engineers and one holding a mining engineering diploma, the potential exists that these persons should be able to obtain their SCO certificates (my main purpose for being in Zambia is to train the rock engineering staff to ensure that the mines have the basic skills within the local workforce to ensure and monitor wall stability) without too much difficulty. (The sooner that I can get these skills developed, the sooner I will feel comfortable in returning back home and continuing with my career in other parts of the world.)
Fortunately, the staff at Sentinel Mine are also involved in greenfield projects and are quickly gaining exposure to different study levels and the complexity of geotechnical data that informs the rock engineering design recommendations.
Wall stability monitoring Besides visual monitoring, three robotic total stations and prisms are installed on the crest of the three stationary walls. A radar unit will be installed and commissioned in July this year, effectively retiring the three total stations (although these may be used at identified, localised potentially problematic areas around the pit).
General stability issues Most of the current benches are still in saprolite, and hence the more serious stability issues that have been experienced on this mine have been associated with wall sloughing (saprolite) and planar/wedge failure (saprolite and sap-rock). The geometry of the walls in one area of the pit promotes planar sliding, as the bench face and overall slope angles are steeper than the dip of the lithology/foliation planes. Drill and blast design review is a continuous practice, as these specific walls have experienced numerous blast-induced damages, affecting multi-bench stability.
Mining equipment
Because of the size of the mining equipment being used on this operation, I thought it necessary to inform you of the more impressive units, these being:
Two rigid trolley-assist (pantograph) dump trucks (from different manufacturers) are used, these being the Liebherr T284 (363-ton payload) and Komatsu 960E (360 short-ton capacity). In addition to these very large dump trucks, Sen-tinel Mine currently has a LeTourneau rubber-wheeled loader that has a bucket capacity of 70 tonnes and is over two stories high. A second unit is underway. There are very large hydraulic shovels loading the dump trucks and two 12-metre diameter ball mills in the processing plant.
Example of equipment size.
Living in Kalumbila The Trident Wetlands Estate (TWE) is the housing complex for expatriate labour working for Kalumbila Minerals Limited (KML). An 18-hole golf course is nearing completion, although golf competitions have been played on the existing nine holes. The estate is built on the bank of the Musanghezi Dam (a dam wall was constructed upstream of Sentinel Mine, as the Musanghezi River actually flowed through the surface mine’s footprint).
Although this estate is not as developed as KGE is, there are more areas of natural bush and trees on this estate, which provides the residents with the experience of living in the bush. The same facilities as at KGE are available to the TWE residents, although with this mining lease area being far bigger than that of Kansanshi Mine, the wildlife that have been reintroduced into this estate have a wider area to roam, and hence game-viewing is not as rewarding as at KMP. However, the Musanghezi Dam is large enough for powered watercraft and kayaks, and fishing competitions also form part of the formal leisure calendar. An additional wildlife species that exists at this site comprises crocodiles, which have been seen on Chisola Dam, which is upstream of Enterprise Mine.
Chisola Dam and the bush surrounding the guesthouse at Kalumbila Hill.
The town of Kalumbila is small and has been developed from scratch by FQML and the KML shareholders. Fortu-nately, a clinic has been built and staffed, as the prominence of malaria at this site appears to be far higher than that at KMP. Initially, additional investment was going to be provided by Holiday Inns, Fruit & Veg Centre, and Builders’ Warehouse, to name a few, but the decision-making process to facilitate foreign investment interest within Zambia put an end to this influx of investment which would have boosted the local economy and facilitated job creation, skills upliftment, etc. However, the township (I have been informed that this is NOT a village) has an informal food market, a Choppies Supermarket, a “hotel” more like an apartment block, a small police station, some civil construction supply warehouses, and formal housing for the workforce, which they can either own or rent for accommodation.
Conclusion Without sounding like a marketing company, I must admit that FQML appears to be the one mining company that I have come across in my current 30-plus years in the mining industry that has invested sustainably in the communi-ty in which they are operating, particularly in Zambia’s North-West province. Their contribution is not only in infrastructure (e.g. schools, clinics, hospitals, teachers’ training colleges, mining villages, road building, power sup-ply, and water wells), but also in training opportunities (trades, farming, teaching, etc.), promoting and facilitating entrepreneurial skills and opportunities, and conservation (rehabilitating deforested areas caused by both mining activities and charcoal makers – refer to the Allan Savory conservation effort, reintroduction of ‘native’ wildlife, etc.).
The opportunity to mentor and share my knowledge of rock engineering, however little and focussed it may currently be, that I have been afforded in Zambia is truly a fulfilling one. The Zambian people are generally a very respectful nation, and are eager and willing to learn. This makes my task of knowledge transfer so much more enjoyable.
My advice to those members of SANIRE who may read this article: “Enhance your knowledge of the reaction of the rockmass to your rock engineering design in your current environment, but do not limit it to specialising in that specific commodity or mining method – there is so much more to learn and stimulate your interest in the science”. Share this knowledge and experience with your colleagues and fellow SANIRE members (potentially us-ing the SANIRE Newsletter as a vehicle to share your experiences and thoughts).
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