Water dust suppression at Dampier port. Image: Department of Water WA.
BY ELIZABETH FABRI
AUSTRALIA is one of the driest continents in the world, and mining is thirsty business. In remote areas of the country water can be both scarce and overabundant, forcing mining operations to continually advance water management strategies and technologies to secure supply, minimise environmental footprint, and ride through extreme weather events such as cyclones, flooding, and droughts.
Water management in mining is a hot topic in all mining jurisdictions across the country.
During 2014-15, an estimated 76,140 gigalitres (GL) of water was extracted to support the Australian economy, according to the Australian Bureau of Statistics (ABS).
Of this amount, 768GL or 4.4 per cent was from mining operations; a sizeable increase from the 652GL consumed by mining in 2013-14 and 489GL in 2009-10.
Like many industries, the resources industry requires access to a reliable supply of water to effectively carry out operations; from supplying drinking water to site workers, washing ore, managing dust emissions, slurry tailings and wastewater services, to generating hydroelectric power.
Water can be sourced from surface or groundwater systems, varying from site to site and depending on the size and location of the mine and volume of water required for different ore types.
On average it takes about 1690 litres of water to process a tonne of gold ore, and about 773,000L to produce a kilogram of gold, Monash University research found.
Yet, water is a finite resource and miners must incessantly innovate to reach a point of sustainability across their operations, and quieten concerns from local landowners and environmentalists alike.
Mining operators are faced with tough decisions daily on how to extract and dispose of water safely and cost effectively, and ensure no pollutants flow out into the environment, such as lead and uranium contamination.
Mining operations are generally positioned in isolated regions where established water and sewage infrastructure are not readily available, and wastewater rich in metals and harmful particles require intensive treatment.
Queensland Resources and Mines minister Anthony Lynham said water management in mining was an important issue in all States, and a modern water management framework would ensure mines had continued access to water while keeping operational costs down.
“For example, coal mines need water to operate and wash their coal,” Dr Lynham said.
“Water is also used for drilling, for construction of infrastructure, for dust suppression to protect air quality, to revegetate rehabilitated land, and for the accommodation of the workforce.”
While much attention was paid to water security and sustainability, auxiliary water management was also essential in areas where wet weather and cyclones were rife.
Cyclone Debbie, which passed through Queensland late March, is just a recent example of how wet weather can have an impact on mining, causing flooding in pits and significant damage to infrastructure.
“The State’s mining industry has been significantly impacted by the effects of Tropical Cyclone Debbie, mainly due to rail infrastructure damage which has slowed some levels of production,” Dr Lynham said.
“Broadly, the modern mining industry responds to weather events through careful planning, particularly with regards to emergency preparedness and worker safety and health.
“For example, mines in the path of Tropical Cyclone Debbie proactively suspended operations for the duration of the weather event and resumed operations in a controlled manner.”
Meanwhile in WA where the climate was typically a lot drier, mining operations had to think outside the box to ensure sustainable supply in months with no rainfall.
“The increased scale, complexity, concentration and commodity diversity of resources activity in Western Australia have all had an impact on the industry’s approach to water,” Department of Water WA Regional Delivery and Regulation executive director Paul Brown said.
“For example, in the Pilbara region, the expansion of port, rail and road infrastructure has led to rising demand for construction and maintenance water supplies.
“Miners are often operating in areas where water supplies are associated with local environmental or Aboriginal cultural values and with existing or perceived future competing uses, and in addition, much of the easy to find water may already be used or allocated.
“All of these factors have served to heighten industry understanding of the value attached to water and the need for greater water innovation and efficiency, and the importance of compliance with regulatory, allocation and licensing requirements.”
Department of Water officer inspects mineral sands mine dewatering in WA’s South West. Image: Department of Water WA.
Water management trends
Many miners in Australia are exploring water efficiency plans and new technologies as a key part of their business planning.
“Some local examples include miners exploring alternative approaches to dust suppression to reduce water use and improved water management strategies such as paste reinjection and the reuse of tailings water excess,” Department of Water WA Regional Delivery and Regulation executive director Paul Brown said.
Miners were also building dams for water storage and dedicated water treatment plants to process water into usable qualities.
Techniques that have been used to manage water included building upstream dams to reduce risk of water contamination from waste rock and exposed ore; installing covers and liners on waste rock and ore piles to reduce risk of contamination; recycling water used to process ore to reduce the amount of water used during a treatment; allowing water to evaporate in ponds; capturing drainage water through liners and pipes and direct to tailings dams; and desalination plants.
In South Australia alone, more than 50 small desalination plants were already in operation in the State.
The resources industry was also working closely with METS companies to develop innovative technologies to help better manage water and reduce operation costs.
CSIRO, for example, recently developed a new technology called Virtual Curtain, which used hydrotalcites to trap metal contaminants and remove them from wastewater.
Adelaide-based company Micromet had also developed a Generation 3 water treatment machine that used electrolysis to remove pollutant materials.
In addition to developing its own set of rules and guidelines for water management, mining operations in all States are required to adhere to strict Government regulations.
And today information is more readily available than ever before to assist miners with the process.
In 2014, the WA Government introduced a new water mining guideline to inform miners about the regulatory assessment and approvals.
“A key objective of the Water in Mining guideline is to ensure mining companies in WA use water efficiently and that fit-for-purpose water is used wherever possible in mining operations,” Mr Brown said.
“It is a one stop document for all regulation and approvals relating to mining proposals.
“To help streamline approvals and licensing, minimise duplication of processes and reduce red tape, the guideline is aligned with approval processes administrated by the Department of Mines and Petroleum, the Environmental Protection Authority and the Department of Environmental Regulation.”
Mr Brown said the Department of Water WA required miners to demonstrate an understanding of how water would be managed over the life of a mine and how issues would be prevented or minimised after its closure.
He said miners must provide detailed hydrogeological and groundwater modelling data with their water licence applications, which was then reviewed by the department and compared with regional water plans to ensure the abstraction, use and discharge would not adversely impact the environment.
“One major change in regulation that has a positive impact by reducing unnecessary red tape for the mining sector was the new 26C exemption order enacted under the Rights in Water and Irrigation Act 1914,” he said.
“This order allows for non-artesian wells that are used solely for the purpose of monitoring water levels and/or water quality to be exempt from licensing.
“Previously any non-artesian bore drilled for monitoring purposes needed to be licensed.
“By exempting these bores from licensing miners are free from unnecessary administration in regard to creating and maintaining them, which saves time and money.”
Environmental breaches however still occurred, with Fortescue Metals Group subsidiary Chichester Metals as a recent offender.
In April, the miner was fined $25,000 over a hypersaline discharge back in 2015 that impacted vegetation at Cloudbreak Iron Ore Mine in the Pilbara.
Between 2.5 million and 3.6 million litres of hypersaline water (close to double the salinity of seawater) was released into nearby vegetation.
The miner immediately notified the Department of Environment and cooperated with DER during the investigation.
Further east in Queensland, the State Government had passed new laws in November which ordered all mines in development that will have an impact on groundwater to obtain an associated water licence, excluding Adani’s Carmichael mine.
“The Government has recently made changes to ensure that before a mine receives a limited right to remove groundwater to ensure the safe operation of the mine, the impacts must be assessed up front and considered in granting the environmental authority,” Dr Lynham said.
“Also, mines that have already received their environmental authority but have not yet started taking associated water will be required to apply for an Associated Water Licence, to make sure that in every case the impacts are assessed before the right to remove the water can be granted.”
Dr Lynham said Queensland currently had 24 water plans in place through which it ensured secure water supply and management.
“Recent legislative amendments mean that when groundwater may need to be removed to allow for safe operation of the mine, this will now be assessed up front through the environmental authority, with a comprehensive framework for ongoing management to ensure that make good arrangements are in place for any potentially affected landholders,” he said.
In April, the State Government gave Adani’s Carmichael mine approval to take 4.55GL of groundwater water each year.
“The mine’s Associated Water Licence and its EPBC approval both require Adani to offset any groundwater it incidentally removes from Great Artesian Basin aquifers,” Dr Lynham said.
“Adani intends to achieve these offsets by capping and piping free flowing bores in the GAB.”
Monitoring mine dewater discharge into the Oakover River. Image: Department of Water WA.
In recent months, responsible water management has been especially high on the global agenda, with the International Council on Mining and Metals (ICMM) announcing new commitments on water stewardship and a practical guide to consistent water reporting.
On 10 January, ICMM released its new water stewardship position statement which aimed to improve water security across the board.
The position statement was a binding document for ICMM members which required them to publicly disclose the company’s approach to water stewardship; allocate clear responsibilities and accountabilities for water; integrate water considerations in business planning from company strategies, life of assets to investment planning; and publicly report company water performance, material risks, opportunities and management.
ICMM’s members included 23 of the world’s leading miners, such as Rio Tinto, BHP Billiton, MMG, South 32, Newmont, Barrick, AngloAmerican, AngloGold Ashanti, and Glencore.
“Society will not be able to meet the sustainable development challenges of the 21st century without improving the management and use of global water resources,” ICMM chief executive Tom Butler said.
“As an industry we have a leading role to play in contributing practical solutions to water resource challenges.
“Water is vital for local communities, the natural environment and for businesses so leadership on water stewardship is required from all parts of society.”
On 22 March, ICMM also published a 72-page A practical guide to consistent water reporting report, which included a new minimum disclosure standard for external water reporting using consistent and standardised metrics.
Mr Brown from the Department of Water WA said the ICMM guidelines built on the efforts many miners were already undertaking in working with government agencies during the application and approval process.
“Leading practice water management in the resources industry involves miners and explorers developing clear water management objectives, establishing strategies to meet defined objectives and creating an adaptive management framework,” Mr Brown said.
“Clear strategic water planning will lead to informed and consistent water monitoring and reporting.”
Strategies for improvement
Despite the increasing attention paid to water security in mining, there were still areas for improvement.
“Key issues currently facing the industry include water availability; water allocation limits; licensing requirements; competition between other water uses and the need to meet environmental and other regulatory requirements,” Mr Brown said.
“For example, as below water table mining sees miners shift away from bore fields and toward mine dewatering, issues associated with disposal and reuse must be managed and addressed.
“The accumulative impacts of mine dewater continues to be an important issue.”
Mr Brown said miners were increasingly required to understand, plan for and address complex and interrelated factors that affect water supply.
“These include competition from other users, allocation and licensing issues, regulation and compliance, the need for improved efficiency and innovation and the effect of the drying climate trend in the south west of the State,” he said.
Concerns of dam failures were also shared by the industry following two significant tailings dam failures in 2014 and 2015, including BHP Billiton and Vale’s Samarco Fundão tailings dam in Brazil.
Mining companies such as South32 have released sustainability reports covering all bases.
“Preventing tailings dam failures is vital to the mining industry’s ability to maintain the trust given to us by communities around the world to manage their land and natural resources safely,” South32 stated in its Dam Management report.
“At South32, we monitor and manage our tailings dams; we assess the risks for each tailings dam, taking into account the materials contained, the location and other factors to identify and put in place the most appropriate failure prevention mechanisms, or controls.”
In Queensland, the State Government established a new water panel on 31 March, to provide independent advice to the government on water planning issues.
“The Queensland Water Act Referral Panel will advise on water planning, such as the size of reserves which may eventually be available to agricultural users and industry,” Dr Lynham said.
“Mining, like any industry must go through a rigorous assessment process before receiving approval to access surrounding water supplies.
“There is a clear need for the mining industry to coexist with other water users and to have measures in place to promote co-existence.
“By using water wisely and demonstrating industry best practice the industry will continue to achieving this balance with communities and surrounding industries.”