Impact of climate change on soil remediation: CDE

Following extreme weather conditions across Australia, Daniel Webber of CDE explains the reality of climate change and how it threatens to unearth the history of Australia’s soil contamination, highlighting remediation solutions that can remove toxins from the environment.

This summer, Australia faced devastation from harsh weather conditions, having experienced some of the worst bushfires on record, extreme dust storms across New South Wales, flash flooding in Queensland and long periods of drought.

Daniel Webber, CDE Business Development Manager, says without stark intervention, the consequences of global warming will be felt for decades to come.

Indeed, the Intergovernmental Panel on Climate Change reported temperatures could rise by 1.7°C by the end of 2100 and sea levels could continue to rise globally.

Daniel explains that there lies a delicate balance between climate and its impact on Australian soils, and the rate of change is having a negative impact on contamination levels.

Contaminated soils are a key contributor to hazardous waste in Australia, yet the full extent of soil contamination is not yet fully known,” he says. 

This is due to variants in reporting between districts, Daniel says, and a lack of historical reporting.

The Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE) reports over 160,000 contaminated sites nationally. Of these, it’s estimated less than 10 per cent have been remediated.

“Australian soil has been contaminated with conventional and emerging contaminants for decades, including heavy metals, hydrocarbons, organic matter and manmade chemicals,” Daniel says. 

He adds that increasing soil temperatures from climate change and recent bushfires has led to increased soil toxicity and greater bioavailability.

“These weather patterns are having devastating effects on our soils and will unearth years of historical contamination,” Daniel explains. 

“In fact, research has shown the long-term effects of climate change, with increasing floods and drought conditions facilitating the movement of soil-based contaminants and soil erosion.”

A study by CRC CARE found soil erosion at a rate of 70-300 tonnes per hectare (tph), compared to what were defined as typical losses in the region of 60-80 tph.

“Our changing weather is causing the level of soil erosion to increase and dust storms will accelerate the spread of toxic pollutants in exposed soil,” Daniel says.

The movement of contaminants in dust storms presents significant health and environmental risks, as pollutants enter the air and water before finally settling into the soil again.

“Exposure to toxic contaminants can have a devastating impact on our health so we must find ways to diminish the risk,” Daniel says.

Many argue contaminated soil sites surrounding our waterways and agriculture lands are those which urgently require remediation.

“Our peers in the waste industry and local government are determined to clean up years of contamination and have already successfully remediated inorganic and organic materials. Yet we cannot do this alone, we need more to join us as we try to make Australia’s soils safe again.”

Successes had been reported. In its 2016 paper, Soil: Formation and Erosion, Australia State of the Environment stated soil ‘erosion rates are equal to soil formation rates.’

However, it remains to be seen how recent and unprecedented bushfires will affect this ratio, or by how much it will set remediation efforts back,” Daniel says. 

Outlining how CDE’s bespoke soil washing solutions can support this effort, Daniel says the company’s technologies utilise a suite of mechanical, chemical and biological processes for recovering washed solids such as sand and aggregates. 

“Contaminants are transferred into the water phase which are effectively treated to produce recycled water for reuse within the process.”

According to Daniel, CDE’s bespoke solutions can be tailored based on tonnage and level of contaminants to ensure maximum efficiency within every project CDE delivers. 

“Our systems provide savings on landfill charges, prevent extra investment in waste storage equipment, and introduce new materials for reuse,” he says. 

“We can no longer ignore soil contamination; we must utilise remediation technology to help us eliminate potential risk to human health and to protect the world around us.”

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The value of waste: CDE

Waste Management Review explores how CDE wet processing technology is supporting Melbourne-based recycling company Repurpose It to reduce a reliance on landfills.

Operating from its 150-acre rehabilitated quarry site in Epping, Repurpose It has an ambitious vision to achieve a 100 per cent recycling rate across its complete waste portfolio.

Likewise, it aims to ensure zero unnecessary waste is destined for landfill. This vision is perfectly aligned with CDE, an industry-leading manufacturer of wet processing technologies, whose ethos is unlock a “New World of Resource”.

To achieve its aspirational environmental aims, George Hatzimanolis, CEO of Repurpose It, turned to CDE to design and engineer a state-of-the-art solution to transform construction, demolition and excavation (CD&E) waste, along with contaminated railway ballast, into in-spec sand and aggregate products that meet the requirements of the local building industry.

George says Repurpose It is committed to recycling products at the end of their lifecycle to transform them into materials that will be used at the beginning of a new lifecycle. These include waste previously considered difficult to process, he adds.

“To achieve 100 per cent recycling of construction and demolition waste, we required a wet processing solution that could efficiently separate and wash every available fraction of material in the feed,” George says.

CDE’s solution, a first-of-its-kind in Australia, incorporates a selection of modular elements that work in synergy to produce best-in-class results, including an AggMax logwasher, the latest in the CDE patented Infinity screening range, a ProGrade H2-60 screen, an EvoWash sand classification and dewatering system, conveyors, a decanter centrifuge and AquaCycle thickener.

Every day, the plant processes up to 150 tonnes an hour of CD&E waste into high-value construction products, which would have otherwise been bound for landfill.

CDE’s customised solution processes CD&E waste and rinses and grades it to make six in-spec products, four aggregates (4-10, 10-20, 20-150, 50-100 oversize) and two sands (0-2 and 0-4).

Daniel Webber, CDE Australasia Regional Manager, says entrepreneurial companies such as Repurpose It have identified that the Sydney Basin and Melbourne are running out of sand.

“The depletion of local sand reserves means that construction and concrete companies now have to transport sand via road from further away or turn increasingly to the production of manufactured sands from hard rock deposits which are more expensive to mine and more hard-wearing on plant and equipment,” Daniel explains.

“This is where CD&E waste processing plants come into their own. They accept waste feed from metropolitan areas and clean it to repurpose it back into the local construction market.”

At the same time, Daniel says there is limited room available for tailing ponds.   

“CDE’s world-leading water recovery and tailings treatment technologies are used to make dry tailings that can be transformed into marketable products themselves,” he adds.

Hand-in-hand with protecting the planet’s finite natural resources is protecting the Earth itself and minimising the carbon emissions associated with the industry.

Vitally, the innovative wet processing plant commissioned for Repurpose It by CDE enables the waste-to-resource business to reduce its carbon dioxide output by more than 84,000 tonnes per year, based on processing 500,000 tonnes of feed material.

“Our investment demonstrates our commitment to reducing the construction industry’s reliance on extractive resources and underpins our company values of creating value from waste,” George says.

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Sustainable mining gains traction: CDE

Adam Holland, CDE Meta, speaks with Waste Management Review about how wet processing can transform mining waste into a sustainable value-added resource.

While sustainable mining might appear like a contradiction to those in the stereotypically green resource recovery industry, it’s a movement that’s gaining global traction.

With rising demand for quality metals, in addition to increasingly stringent environmental legislation, protecting finite natural resources and extracting value from “waste” is not just environmentally sound, but good business.

For CDE Meta, the mining arm of international wet processing design and manufacturing company CDE, delivering sustainable mine operations via iron ore beneficiation is central to its “New World of Resource” purpose.

According to Adam Holland, CDE Meta Head of Business Development, with billions of tonnes of low-grade and overburden iron ore stockpiles around Australia, there is a growing appetite to invest in sustainable practices.

“CDE strives to make it as easy as possible for companies to use their waste products for the greater good, while also delivering return on investment,” Adam says.

“We’re committed to maximising product value while reducing environmental impact. Sustainability is at the heart of all CDE projects.”

CDE was recognised for its commitment earlier this year, winning two awards, one in Ireland and one in South Australia, for its Iron Baron and Iron Knob projects with SIMEC. The two awards, gained on the same day at opposite sides of world, are a testament to the global reach of the company and the strength of its sustainability driven purpose.

The awards, Adam says, highlight that while sustainable mining might not be taking over the sector just yet, solutions are available, and a return on investment is possible for resource companies interested in taking a greener approach.

The SIMEC projects, commissioned in 2017, involves two separate wet processing plants with a combined capacity to convert 17 million tonnes of historic low-grade iron ore overburden waste into a high-value product. Without processing, iron ore waste often sits in unused stockpiles.

“With a processing capacity of 950 tonnes per hour, the two plants are successfully recovering high-quality iron ore from 100-year-old-plus-low grade mining waste feed material,” Adam says.

“Our plants beneficiate iron ore waste at 42 to 53 per cent Fe content through washing and gravity separation up to 63 per cent, at an almost 50 per cent yield.”

CDE was approached by Arrium (shortly after it was acquired by SIMEC) in 2013, before signing a design and construction contract in 2016.

“Because they were dealing with a historic stockpile, and therefore variable feed, SIMEC recognised CDE’s modular approach as a differentiating factor with inbuild flexibility,” Adam says.

“SIMEC understood the inherent value of its iron ore waste but needed our assistance to develop a cost-effective beneficiation solution.”

While the plants, Iron Baron and Iron Knob, engage similar processes, Adam says the Iron Baron facility is more complex – beginning with a 42-millimetre down feed.

Each process module is spaced out and separated by conveyors and pipe runs. This, Adam says, provides operators with superior access and flexibility when maintaining the plant and allows additional processes to be added for optimisation with minimal downtime to cope with feed material that changes periodically.

The Iron Baron process begins with two L55 hoppers, each feeding 350 tonnes of material per hour. Conveyors then transfer material into CDE’s patented P2-108 double deck infinity screens which wash and split the ore between fine and course beneficiation circuits.

Following initial screening, the course fraction travels to CDE’s AggMax – a combination of a Rotomax logwasher and dewatering screen.

“This is where the ore is scrubbed to liberate any smaller particles and break off impurities,” Adam says.

“It has performed exceptionally well – running for well over a year before we had to change out the paddles.”

Once the material is cleaned and scrubbed, it travels up more conveyors for dry screening, and then enters a fine or coarse jig for gravity separation.

“The plant then separates material into three stockpiles: a course product, fine product and rejected material,” Adam says.

“Given the nature of our process, however, even the rejected material can be reclaimed, with SIMEC using it for road construction around the mine.”

Adam says attention to maximum reuse was also behind the decision to install AquaCycle thickeners at the site. The thickeners, he says, produce a sludge from the reject slimes and enable recycling of 90 per cent of process water back through the plant.”

Additional benefits of the unique CDE modular solution, Adam says, include minimal civils, a faster, safer and reduced risk installation due to factory testing and per commissioning process, as well as reduced capital and operational expenditure.

“What sets these plants apart is CDE’s ability to design a modular solution, tailored to SIMEC’s unique requirements, delivered on a turnkey basis for cost-effective operations in a mining and iron ore context. This provides a superior return on investment for SIMEC,” he says.

In addition to effective return on investment, Adam says CDE is committed to providing ongoing customer care, adding that it works with a “customer-for-life model”.

“As part of this project, CDE has also invested in a significant vendor-held spares consignment that SIMEC can draw down as and when required,” he explains.

“We also have two full-time employees who work at the site and support SIMEC through maintenance and manage the VHS consignment, ensuring that bin levels are replenished for optimal plant performance.”

Adam says he hopes CDE’s SIMEC plants serve as a case study for larger resource companies seeking to increase operational sustainability. He adds that for every tonne of ore waste processed, mining companies can significantly extend the life of their mine and maximise reserves.

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Concentrating contaminants: CDE

CDE’s Daniel Webber explains how high-pressure filtration and decontamination can increase the resale potential of construction and demolition waste.

The NSW EPA’s new construction and demolition (C&D) waste guidelines, released April 2019, highlight environmental risk via contamination and poor recycling processes as a core concern.

Daniel Webber, CDE’s Regional Manager for Australasia, says the presence of contaminants in the C&D stream is particularly significant, given one of the material’s major resale markets is road base.

“If the material used in road base contains heavy metals or polycyclic-aromatic hydrocarbons, which are known to be carcinogenic, those materials can leach out and penetrate the water table, and once they enter the water table, they can potentially contaminate drinking water,”
Daniel says.

For CDE, an international materials wet processing design and manufacture company, eliminating contaminants in C&D waste is critical to market viability.

“One of the first things we noticed when we first began working with the C&D waste sector was that there are no completely pure C&D sites.

“They all drag contaminated soil in eventually, and when there are no clean sites, there’s no clean materials. CDE quickly learned that this was something we needed to address with our clients.”

A central challenge to addressing the issue, Daniel says, is the variability of C&D contamination regulations across jurisdictions.    

“Conflicting regulations range from waste levy rates, urban development and state planning zones, to contaminant levels and disposal requirements,” he explains.

“We need to be across all the various legislative requirements and, as such, prioritise working in partnership with our clients to achieve that.”

According to Daniel, leachate is a focal point when dealing with C&D. He adds that because of the location of most C&D plants, large tailing ponds are often unfeasible.

“C&D is not like virgin mining or quarrying, which happens in the outer suburbs or the regions. Most construction sites are in metropolitan areas,” he says.

“To minimise transportation costs and therefore maintain resource recovery practicality, a lot of resource recovery also happens in metropolitan areas, meaning operators have to be much more cognisant of the contaminant problem.”

To remove contaminants, CDE facilitates two separate processing methods, both of which can be customised to suit individual client needs. Daniel adds that contaminants include anything from unwanted material such a plaster board and heavy metals, to dangerous chemicals such as PFAS.

“To wash and process contaminated C&D material, CDE designs plants that push contaminants into a tertiary water body for filtration, or alternatively, into sludge for processing via filter press technology,” Daniel says.

“When a client chooses the filter press option, their material is passed through mesh under extremely high pressure to produce a dry filter cake, which is then discharged into a bay below the filter press enclosure.”

Daniel says the filter press method allows CDE-designed plants to salvage 90 per cent of the original feedstock material.

“If a client is running a 200-tonne-per hour plant, with feeds coming through the front end, CDE equipment can concentrate existing contaminants into 20-tonne-per-hour of feed material.

“That means 180 tonnes of material can be repurposed and put straight back into the market as clean construction material.”

Additionally, Daniel says by concentrating contaminants, operators can save on landfill charges and prevent extra investment in waste storage equipment. Effectively removing contaminants also requires high-energy scrubbing and dewatering cyclone systems.

“By introducing CDE technology, plant operators can eliminate the need for settling ponds, reduce the space required to accommodate a washing plant and maximise water recycling.”

CDE’s minimum target, Daniel says, is an 80 per cent recovery rate, designing plants to increase traditionally unusable recycled sand and aggregates for multiple resale applications.

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