Consulting engineering firm SRK Consulting South Africa, which has been active in Zambia for several decades, says it is critical for miners to have detailed and accurate data on their orebody as a starting point for mine plans and future development.

“For Zambian mines to increase future production, the key is to develop sufficiently far ahead of their mining operations to create flexibility for the mining plan as market conditions or other factors change. This flexibility is what a mine needs if it is to take best advantage of higher prices while increasing the asset’s value over time,” says SRK chairperson Roger Dixon.

SRK partner and principal geologist Victor Simposya says an important part of SRK’s work has been to assist clients in increasing production in their mining operations. “In some cases, we have even gone back to their original drillhole data to model their orebodies to retrieve more detailed insights for planning purposes. Many of the operations we consult for have a long history of mining and have historically relied on manual planning systems,” he adds.

SRK prinicipal mining engineering consultant Boniface Mwila notes that, through prefeasibility studies carried out in Zambia in 2012, SRK was able to present a variety of options for management to determine the best recovery plans at the lowest cost, in light of the falling ore grades obtained in some of the mines.

Simposya mentions that by applying state-of-the-art computer software, SRK has carried out three-dimensional (3D) modelling to allow for a better understanding of an orebody’s mineralisation, so that management can increase production at their mining plants.

SRK has been using this technology for many years and has been able to use its knowledge and experience of the geology and mineralisation of the Lufilian Arc – which is part of a system of orogenic belts in Southern Africa, formed during the Pan-African orogeny – to guide clients in planning the development of their plants moving forward. This has been particularly useful when foreign companies come into Zambia and need to familiarise themselves with local conditions. These modelling interventions have also had long-term impacts for clients beyond the immediate production gains.

“Through modern geological modelling techniques, we have been able to indicate the potential for future growth beyond their existing mine plans. These are exciting developments for the companies concerned and the Zambian mining sector as a whole, where future value can be identified in parts of the orebody not fully explored before,” highlights Simposya.

He adds that the retiring of experienced personnel at mining houses has resulted in a lack of certain skills. There is also a lack of skills to undertake the complex 3D models and to convert them into mine plans.

“The value of this baseline modelling is further leveraged when it is part of a structured decision-making process. Risks can be better managed when you’ve got definite decision points in the process of considering new projects or expansions. This way, the company can start its engineering work with a scoping study, then move on to a prefeasibility study and a feasibility study before embarking on detailed design,” Dixon points out.

SRK mentions that the low copper price has had a detrimental effect on the Zambian economy and that it is important to ensure that a project will clear the necessary financial and operational challenges before it is given approval to proceed to the next stage.

“Investing in geological data gathering, modelling, planning and development to ensure that suitable mining areas are opened up at the appropriate times in the mine’s life will help mining companies in their expansion plans.

“Mines need to regularly plough back revenue into detailed planning activities and development, as this is relevant in opencast mines, as they are underground operations,” explains Dixon.

Integrated Water Management in Mines
SRK mentions that another constant challenge and a main cost factor for Zambian mines is managing the country’s high rainfall and groundwater levels.

“The Copperbelt is subject to high tropical rainfall events during the summer months – from about October to April – with an average rainfall of 1 200 mm/y. This requires not only effective storm water controls to handle the high rainfall but also the management of groundwater inflows associated with the hanging wall and footwall aquifers associated with the mineworkings,” says SRK principal hydrogeologist Diana Duthe, stressing that this enables the management of potential flood risks associated with the proximity of mine infrastructure to major water courses subject to such high seasonal catchment flows.

She adds that groundwater inflows into the mineworkings can lead to more than 300 000 m³ of water having to be pumped out daily in order to maintain safe underground working conditions. A sound understanding of the groundwater ingress, developed through groundwater modelling, is then required to evaluate the most efficient dewatering options to maintain safe conditions.

“SRK’s approach is to develop an Integrated Minewater Management Plan to effectively manage the surface water and groundwater interactions and management requirements within a mining project. In Zambia, the mine water balance is generally positive – there is usually too much water rather than too little – and excess water needs to be disposed of in an environmentally responsible manner. To an extent this can be achieved by intercepting groundwater inflows before it is contaminated by mining activities, and by separating clean and dirty water through effective surface stormwater control,” Duthe explains.

It is also important, she says, to recognise that the presence of such vast amounts of surface and groundwater also has significant effects on pit-slope stability design for opencast mines, as this design, which must also take into account geotechnical factors, will determine what is required to access the orebody, informing the economics of the openpit and for how long will it remain economical.

Simposya says that although there are challenges in the Zambia mining sector, the fundamentals for copper consumption remain good and demand from the Chinese economy, in particular, bodes well for the future development of the Zambian mining sector.