Pressure is on extractive operators globally to employ technologies that reuse water responsibly. Business development managers for a sand washing manufacturer discuss the challenges, costs and logistics of developing a washing plant that satisfies local and international regulations.
It’s incomprehensible for most — the notion that around the globe we face issues arising from water stress on a planet whose surface area is made up of more than 70 per cent water and whose total water volume – a staggering 96.5 per cent – is contained within our oceans. Whether for consumption or sanitation, clean water in some parts of the world is taken for granted, as we fail to recognise the processes and infrastructure needed to maintain a clean water supply or neglect to acknowledge that basic access to clean water is not universal.
In 2017, 785 million people lacked a basic drinking water service. This number included 144 million people that were dependent on untreated surface water, 206 million who had access to an improved water source but were required to make a 30-minute trip for collection, and 435 million who were extracting water from unprotected wells and springs.1
While at the most extreme end of the scale more than two billion people live in countries experiencing high water stress,2 almost two-thirds of the world’s population experience severe water scarcity during at least one month of the year.3
Essential for life, water is also vital for economies and climate regulation. It is of utmost importance, therefore, that our water resources are protected – even regulated.
The mining and quarrying, manufacturing and construction sectors accounted for 10.6 per cent of total water use in Europe in 20174 and the industry compounds water scarcity, water efficiency and wastewater management challenges the world over.
The 2030 Agenda for Sustainable Development5, adopted by all United Nations Member States in 2015, provides a shared blueprint for peace and prosperity for people and the planet, now and into the future. At its heart are the 17 Sustainable Development Goals (SDGs) with 169 associated targets and 230 indicators, which are an urgent call to action by all countries.
CDE recognises that the benefits arising from sustainable practice and processes are two-fold: they are economically advantageous and minimise our impact on the environment. Indeed, they are green from both perspectives. To that end, among the SDGs adopted by CDE is number six: Clean water and sanitation.
All corners of the globe are facing unique challenges. Parts of Romania and Poland are experiencing the worst drought in a century, with the Czech Republic facing its worst in five centuries. In Australia, more than one million fish are estimated to have died between December 2018 and January 2019 in the lower Darling River with drought and over-allocation or precious water resources cited as the main causes6; and in the most remote locations of North and Latin America materials producers are responding to the growing challenge of materials wet processing.
Water scarcity and management is central to each of these challenges, and is echoed by CDE customers around the world, as four of its regional business development managers from across Australasia, Europe, and North and Latin America discuss.
Innovations in the washing sector and the continued advancement of CDE’s pioneering wet processing solutions are supporting quarry operators and materials processors alike to overcome the challenges stemming from water management: cost-effectiveness, efficiency, sustainability and regulatory.
CDE’s modular wet processing equipment can contribute to the easing of water scarcity issues arising from the materials processing industry’s consumption of water resources, greatly improve water efficiency, and better wastewater management practices. The development of technological solutions to tackle these mounting challenges is paramount for many materials processors seeking to boost the profitability of their operation by minimising the consumption of costly water resources.
Daniel Webber, CDE’s regional manager for Australasia, and Stefan Hunger, CDE’s business development manager for Europe and Russia, report of increasing regulations governing the responsible use and management of water in the industry, including those aimed at protecting marine environments and water sources from pollution and over-abstraction.
Webber said the Australian mining industry has adapted to more regulations about its water usage than most other industries.
“Each stage of the mining cycle requires permits, including, among other utilities, water permits,” he said. “The impact of an operation is also subject to strenuous environmental assessments to evaluate the management and use of water resources and the processes that will be employed to prevent the contamination of groundwater.”
In terms of sector, agriculture remains the largest user of water in Australia, accounting for almost 70 per cent of the total water footprint. Industry, however, including mining and quarrying, is on the rise at a time when water storage levels hit a 10-year low in 2019-20.7
“Pressure on Australia’s water resources is mounting on account of population growth,” Webber added. “With this comes greater demand within the agricultural and industrial sectors to support such growth and urbanisation. We’re finding mine and quarry operators are in effect competing against the needs of urban populations, farming, and the environment in terms of water demand which is why governments are taking greater action to regulate its use.”
It is therefore increasingly important for materials processors to invest in an effective water management strategy that ensures a steady supply of clean water to their plants through cost-effective means.
“It’s important to acknowledge that water is renewable when its usage is regulated and managed responsibly, but it is also a finite resource,” Hunger said. “Not only does water recycling make sense from a global environmental perspective backed up by increasingly stringent legislative requirements, but it also ticks all the right boxes in terms of return on investment.”
In Europe, there are about 26,000 aggregates sites, nearly 60 per cent of which are involved in materials washing activities.8
While laws governing water vary around the world, it is a resource that is absolutely essential to the extractive industries and is therefore increasingly under the water management microscope.
In early 2020, in the United States, the Environmental Protection Agency (EPA) provided further clarification to its Waters of the United States (WOTUS) rule which aligns with the Clean Water Act, as Darren Eastwood, CDE’s business development director for North America, explained.
“Confusion caused by the 2015 WOTUS rule resulted in many aggregates businesses across North America incurring significant costs due to the uncertainty around when federal permits were required,” he said. “Its reclarification provides a clear regulatory framework to which aggregates producers can align. Its new definition clarifies that pits and water treatment basins are not subject to additional federal regulation.”
Water as a resource delivers economic value to a range of industries. Within the extractive industries the value of materials is significantly increased when washed, but wet processing in mining and quarrying operations is dependent on water availability and processing plant efficiency.
Bruno Paladino, CDE’s business development manager for Latin America, says the combination of regulatory and environmental considerations with economic factors presents a major challenge for operators washing sand and aggregates.
“Water supply is a key determining factor when assessing the viability of a new project or when considering expanding operations at an existing site,” Paladino said. “Insufficient water supply, particularly in arid regions, will drive up operational expenditure costs significantly in an industry where energy prices already represent 20 per cent of these costs due to the investment in water infrastructure to ensure an adequate supply of clean water is pumped into the plant.”
Research shows energy usage by water pump systems accounts for a significant proportion of global energy consumption across all industry.
Growth, Paladino said, is capped without the capacity to wash and grade sustainably.
“Environmental regulations are becoming ever more stringent. An operator must demonstrate how their project is sustainable and compliant. This becomes increasingly difficult to evidence when adequate water management and treatment is missing from the project.”
Hunger said customers do want to wash but the “footprint, particularly in urban settings, is prohibitive. This is precisely why CDE has invested significant resources into the design and development of compact and modular equipment that can be commissioned in urban areas while also offering the ability for future migration of the plant to where opportunities lie.”
“More often it’s water availability and access that prevents producers getting into the washing business in the first place,” Webber added. “That, and the uncertainty around typical top-up water requirements which, in the case of CDE water management solutions, are very low. The focus is on recycling and recirculating as much water as possible through the system.”
In the Americas, customers using settling ponds to recycle water often encounter significant operational and logistical challenges.
“These require constant maintenance as they accumulate sludge, silt, and other solids that must settle and separate from the water before its removal,” business development director Darren Eastwood said. “Not only do these limit the water storage capacity of the pond but they incur significant maintenance costs. Further still, the limitations of settling pond systems often result in the loss of valuable fines, one of the key considerations in the design of CDE water management solutions.”
Settling ponds also pose significant health and safety risks, too.
“Overflow to account for periods of sustained heavy rainfall, safe access to pumps for maintenance, the strength and integrity of its walls, and the positioning of the pond to mitigate against breach or failure that could pose threat to nearby structures; these are all vital health and safety considerations associated with settling ponds systems,” Eastwood said.
Paladino stressed the importance of safe water management in all regions, but highlighted the urgent relevance of such practices in Latin America.
“Over the past few years, mines in Latin America are looking for new and sustainable ways to continue their exploration, ways that are less impactful on the environment and surrounding communities,” he said. “The use of water is a key factor, as is overall footprint and energy usage. CDE’s modular plant design with water recycling system is the perfect fit to help mines meet these
RECYCLING PROCESS WATER
CDE consistently invests in research and development with the aim of enhancing the capabilities of its premier water recycling and management equipment. At the forefront of its water recycling systems is the AquaCycle, a single, compact, and user-friendly unit that can be applied to high and low tonnages across many markets.
Delivering competitive advantage to its customers, CDE’s AquaCycle accelerates return on investment by maximising production efficiency, minimising the loss of valuable fines, and reducing water and energy costs.
An alternative to water extraction and the costly process of pumping water to the plant, CDE’s AquaCycle is a highly efficient water management solution that minimises costly water consumption by ensuring up to 90 per cent of process water is recycled for immediate recirculation.
After feed material has been washed and classified, waste is sent to the AquaCycle thickener tank. Here, a small amount of polyelectrolyte flocculant is added to the water via an automatic dosing station which forces fine particles to settle on the bottom of the thickener tank. The clean water on the top overflows the weir and is stored in the AquaStore tank before being recirculated around the plant. The result is a highly efficient water recycling system that requires only a 10 per cent supply of top-up water.
Waste sludge is discharged into a buffer tank where a motorised rake in constant rotation ensures the material does not settle and solidify. If further dewatering is required, a filter press or decanter is added to the wet processing solution to eliminate the need for settling ponds.
Though water recycling may seem simple in theory, it is, in practice, much more complex. Water thickeners are not born equal and their efficiency is the result of years of dedicated research, development, and refinement. Every aspect of its design is carefully considered so that the system is responsive to the site-specific needs of its owner.
“We sweat the small stuff,” said Kevin Vallelly, CDE’s director of engineering. “CDE has been co-creating with customers for more than 25 years to deliver collaborative, imaginative and unique processing systems, and this process has been informing and refining our water recycling technologies.”
All CDE equipment is designed to allow plug-and-play operation, that is, the equipment is pre-wired and pre-tested before despatch, designed for rapid assembly and set-up and can start processing material within days of arrival on-site. These design considerations and factory acceptance tests significantly reduce install time and accelerate return on investment.
“Fast return on investment is a very real proposition when the CDE AquaCycle thickener is introduced to a washing operation,” Vallelly added. “It boosts the efficiency of the wet processing plant by maximising the settlement of solids which reduces the quantity of flocculant required, cuts running costs, and optimises the overall efficiency of the plant.”
Return on investment with a CDE AquaCycle is typically achieved in just six to nine months.
Settling ponds are known to be the source of significant revenue losses, not only due to high maintenance costs, site footprint, and downtime, but also because high value fines can become lost and trapped at the bottom of ponds.
“By recycling up to 90 per cent of process water, the requirement for settling ponds is greatly reduced,” Vallelly continued. “With the addition of a filter press tailings management system that need is completely eliminated. When combined with a CDE filter press custom-built fines management system this figure increases to 95 per cent, removing the need for settling ponds altogether.”
Water management systems are becoming a “must have” for mine and quarry operations to comply with environmental regulations. Matters concerning the protection of finite resources on the planet will only become more prevalent, too.
“The benefits of the CDE AquaCycle significantly outweigh their initial investment, not only for the short period until return on investment is achieved, but for the preparedness it offers,” Vallelly concluded. “Water management and water recycling are prevalent issues that will only become more tightly regulated and monitored in years to come. The AquaCycle ensures operators stay ahead of the curve while extracting maximum value from available resources and driving down operating costs.”
The AquaCycle system is available to operators globally and is ready to complement wet processing applications in five sectors – sand and aggregates, mining, construction and demolition waste recycling, environmental applications, and industrial sands.
Source: CDE Global
REFERENCES & FURTHER READING
- World Health Organisation. www.who.int/news-room/fact-sheets/detail/drinking-water
- United Nations. www.unwater.org/app/uploads/2018/12/SDG6_SynthesisReport2018_WaterandSanitation_04122018.pdf
- Mekonnen MM, Hoekstra AY. advances.sciencemag.org/content/2/2/e1500323/tab-figures-data
- EEA. www.eea.europa.eu/data-and-maps/daviz/annual-and-seasonal-water-abstraction-7#tab-dashboard-02
- United Nations Sustainable Development Goals. sustainabledevelopment.un.org
- Murray Darling Basin Authority. www.mdba.gov.au/managing-water/drought-murray-darling-basin/fish-deaths-basin/fish-deaths-lower-darling
- Australian Department of Agriculture. www.agriculture.gov.au/abares/research-topics/water/water-market-outlook-march-2020
- UEPG/UNPG. www.uepg.eu/uploads/Modules/Publications/uepg-unpg-water-management-brochure.pdf