Water shortages in the Rustenburg area put significant pressure on mines and communities alike. By accurately modelling its water balance, Lonmin was able to achieve significant improvements in water use efficiency and water security for all.
Although Rustenburg’s mines had initially developed in isolation, miners soon realised that cooperation and coordination was required to assist authorities with the constrained regional water sources.
From this, it was identified that the accelerated implementation of water conservation and water demand management (WC/WDM) was needed.
Lonmin undertook a systematic approach, using water quality and demand requirements for various mining processes to develop a dynamic water balance model.
The mining house’s WC/WDM programme aimed to ensure sustainable water supply and use, to improve compliance and to inform the development of the Lonmin integrated water resource management system.
A sizeable challenge
Lonmin faced the significant challenges of water shortages and spills, impacted community water services and a substantial compliance burden.
The company was also experiencing frequent plant stoppages due to water shortages, amounting to millions of rand per day in production losses. According managing director Mias van der Walt, Bigen Africa was able to identify several areas for improvement.
The opportunity existed to optimise external water sources, inter-transfer between mining areas, and reuse water in internal systems. In addition, discharges were not controlled and anthropogenic aquifers were not being used as storage sources.
Developing a solution
The first step was to define the water demand for all of the mining areas.
“That in itself was a huge effort because you need to understand the mining plan, what they are producing, the unit water consumption for the various sections, define the water sources, look at the water demand management strategies and then develop the water balance. And with that water balance, come up with different water management scenarios and develop a portfolio and WC/WDM projects,” explains Van der Walt.
No single scenario addressed all success criteria; instead, a cumulative scenario was adopted in order to achieve the strategic
This scenario included the installation of a cross-mine transfer pipeline between the three mines, developing boreholes from rehabilitated aquifers, and maximising local resources.
The result was that no additional water was needed for the mining of tailings, a reduction in Lonmin’s water purchases from Rand Water and reduced environmental discharge.
Lonmin went on to base its long-term WC/WDM programme on the outcome of the optimised scenario. A number of projects were identified, planned and prioritised based on project outcomes in order to achieve the long-term goals.
Significant water savings
This cumulative scenario showed a significant improvement in relation to the base case. Lonmin’s acquisition from Rand Water could be reduced by 4.2 million m3/a – a substantial reduction of 46%. Similarly, environmental discharge could be slashed by 39%, or 643 148 m3/a.
By reducing its demand, Lonmin was also able to free up more water for the surrounding communities, contributing to improved water security. To replicate these successes, Van der Walt believes a change in mindset around water is needed from management level down.
Mine water systems, especially those evolving and expanding over many decades, are extremely complex and dynamic, but significant water efficiency improvements can be achieved.
He argues that there is potential to ring-fence sections of water systems, which can also assist the balance sheet of the mine without burdening their balance sheet.
It is clear that by revisiting and critically assessing an existing mine water system, a win-win scenario for all stakeholders can be achieved.