WATER MANAGEMENT
– creates a stable tailings stream that can be moved with positive displacement pumps . “ Weir Minerals ’ technology strikes the perfect balance between water stability and emissions . Compared with filtered tailings , it produces two to four time less CO 2 emissions , providing a lower total cost of ownership and providing an end result very close to filtration .”
With its GEHO ® range of pumps , Weir Minerals can effectively pump these dense pastes over very long distances if required , allowing miners to store their tailings a significant distance from the mine without having to use trucks for transportation . More generally , the paste produced is relatively stable and requires substantially reduced storage volumes , thereby extending the life of existing tailings storage facilities .
“ Weir Minerals takes a holistic approach to address its customers challenges and help them solve their problems .”
An iron ore customer in Latin America needed a tailings solution to help them meet their future production targets without the need for a new tailings storage facility . Working closely with the miner , Weir Minerals ’ engineers developed an innovative Integrated Solution , which combined Weir Minerals ’ Cavex ® DE hydrocyclones , Warman ® pumps and Enduron ® screens .
This integrated tailings solution will replace the mine ’ s existing thickener plant and is expected to increase water recovery by 35 %, providing more water that could then be recycled back into the process and resulting in a significant reduction in wet tailings .
Moreover , Weir Minerals utilised the tailings to raise the TSF dam wall , thereby turning what ’ s usually a waste product into a usable , valuable product . Ensuring the structural integrity of the wall is obviously paramount , which means that the sand must have relatively free-draining characteristics – or , in other words , sand that ’ s 15 % passing minus 200 mesh ( 75μm ).
This requirement helps prevent liquefaction , the process by which water-saturated , unconsolidated sediments are transformed into a substance that acts like a liquid . Typically , tailings would have to pass through several stages of hydro-cycloning to achieve this sand quality ; however , with the Cavex ® DE hydrocyclone , it can be achieved in a single stage .
With a conventional hydrocyclone , 35-40 % of mass is usually sent to the underflow , but , with the Cavex ® DE hydrocyclone , it is around 45-55 % – making it 10-15 % more efficient than any other hydrocyclone on the market .
McNulty concludes : “ The innovative engineering that underpins TerraFlowing™ technology and Cavex ® and GEHO ® equipment has become a hallmark of Weir Minerals ’
commitment to providing its customers with Integrated Solutions that help them mine more efficiently , while also reducing their carbon footprint .”
SRK : mines need credible standards for water reporting
As a vital aspect of environmental , social and governance ( ESG ) risk , water management was an important feature on the agenda at the recent Mining Indaba in Cape Town ; SRK Consulting has highlighted that the mining sector will increasingly need to report its water-related performance in terms of credible global standards . According to SRK Consulting principal Consultant Fiona Sutton , one of the company ’ s delegates at the Mining Indaba , water stewardship is coming to the fore in ESG reporting – with ESG itself also still evolving a consistent framework that is broadly recognised by the investment community .
“ In the most recent EY Global Institutional Investor Survey , for instance , it is argued that the reporting of ESG performance needs to be measured against a set of globally consistent standards – which could become a mandatory requirement ,” said Sutton . “ With water management ranked by EY as the number one ESG risk in mining , and with ESG itself being the top risk for the second year running , there is some urgency for mining companies to assess water risk in terms of a credible framework .”
She pointed out that water stewardship and biodiversity ( the latter ranked eighth in EY ’ s 2023 risks ) were fast becoming urgent priorities . Factors putting pressure on water resources included population growth , shifts toward more meat-based diets , climate change and other challenges . The world ’ s water is increasingly becoming degraded in quality , she explained , increasing the cost of treatment , and also threatening human and ecosystem health . Furthermore , the physical availability of freshwater resources does not guarantee that a safe , affordable water supply is available to all .
“ The growing significance of water management within ESG strategy means that more rigorous reporting will be demanded by mining company stakeholders ,” she said . “ Better water reporting will also be necessary to access capital and to secure a license to operate .”
More detailed water management reporting will in turn require more trustworthy and useful ESG data , including information related to relevant financial and social impact risks .
“ An effective response to these risks can be rooted in the concept of water stewardship , which provides a process for companies to work collaboratively with other partners to manage shared water resources ,” she said . “ In this way , water stewardship can be an important
component to mitigating corporate water risk and facilitating business growth .”
SRK Consulting Managing Director Andrew van Zyl , who was also at the event , affirmed the critical importance of water risk on the mining agenda – and the importance of global best practice tools like the International Water Stewardship Standard from the Alliance for Water Stewardship ( AWS ).
“ Assurance is a key facet in increasing trust in the quality and accuracy of sustainability information ,” said van Zyl . “ The AWS Standard offers a credible and globally applicable framework for major water users to understand their own water use and impacts with practical guidance on how to effectively manage these impacts .”
SRK Associate Partner and Principal Environmental Geologist Lindsay Shand , another SRK delegate at the event , highlighted the practical value of the AWS standard . “ The principles of water stewardship are drawn from high level environmental imperatives ,” said Shand , “ However , they also give water users a more practical framework from which to tackle their issues of water quantity and quality .”
Applying the International Water Stewardship Standard , explained Sutton , means a more effective evaluation of water use . It guides companies in disclosing aspects such as water governance , metrics , site risks , catchment risks , quality targets , strategies and performance . “ Another way that the AWS standard reinforces – rather than duplicates – existing systems and processes in mining companies , is that it aligns with other reporting frameworks that they might use ,” she pointed out . “ For example , on issues such as compliance , disclosure , stakeholder consultation , safety and health , this standard overlaps well with guidelines and standards from the International Council on Mining and Metals , the World Gold Council , the Global Reporting Initiative , the Global Industry Standard on Tailings Management and the Sustainability Accounting Standards Board – to name a few .”
Several SRK water professionals are AWS credentialed specialists , with specialised training to help clients towards improve corporate water sustainability systems and achieve AWS certification , should they wish to become AWS certified .
From slurry to human consumption : water management in Latin American mining
Water is vital in the Latin American mining industry ’ s operational processes and a substantial amount is used every day for reasons ranging from mineral processing , separation and extraction to the movement of ores across long
MARCH 2023 | International Mining 61