Innovations in the washing sector and the continued advancement of CDE’s pioneering wet processing solutions the company says are supporting quarry operators and materials processors alike to overcome the challenges stemming from water management; cost-based, efficiency, sustainability and regulatory.

CDE says its 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 company states: “Developing 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 Regional Manager for Australasia, and Stefan Hunger, for Europe & Russia, report 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 explains the Australian mining industry has adapted to more regulations surrounding its water usage than most other industries: “Each stage of the mining cycle requires permits, including, among other utilities, water permits. 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% of 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 2019/2020.

He continues: “Pressure on Australia’s water resources is mounting on account of population growth. 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.

Stefan Hunger says, “It’s important to acknowledge that water is renewable when its usage is regulated and managed responsibly, but it is also a finite resource. 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 approximately 26,000 aggregates sites, nearly 60% of which are involved in materials washing activities. 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.

Earlier this year, 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 Business Development Director for North America, explains: “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. 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 hinged on water availability and processing plant efficiency.

Bruno Paladino, CDE Regional 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. Insufficient water supply, particularly in arid regions, will drive up operational expenditure costs significantly in an industry where energy prices already represent 20% 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, he says, 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.”

Stefan Hunger comments that customers do want to wash, “But footprint, particularly in urban settings, is prohibitive. This is precisely why CDE has invested significant resource 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.”

Daniel Webber adds, “More often its water availability and access that prevents producers getting into the washing business in the first place. 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. Eastwood explains: “These require constant maintenance as they accumulate sludge, silt, and other solids that must settle and separate from the water before its removal. 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.”

Bruno Paladino stresses the importance of safe water management in all regions, but highlights 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. 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 new challenges.”

CDE says it 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% 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 re-circulated around the plant. The result is a highly efficient water recycling system that requires only a 10% 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,” says Kevin Vallelly, Director of Engineering at CDE. “CDE has been co-creating with customers for over 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 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 onsite. These design considerations and factory acceptance tests significantly reduce install time and accelerate return on investment.

He adds: “Fast return on investment is a very real proposition when the CDE AquaCycle thickener is introduced to a washing operation. 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 optimising the overall efficiency of the plant.”

Return on investment with a CDE AquaCycle is typically achieved in just six to nine months, says CDE. 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.

He continues, “By recycling up to 90% of process water, the requirement for settling ponds is greatly reduced. 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%, 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.

Kevin Vallelly concludes: “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. 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 around the world 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.