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Sand Processing














The AquaCycle thickener tank stores processed water for recirculation back to the wash plant.
The AquaCycle thickener tank stores processed water for recirculation back to the wash plant.

Customised processing systems offer multiple sand solutions

With sand an in-demand commodity for infrastructure projects, but also subject to rigorous extractive rules, particularly around water usage, producers are increasingly seeking processing plants that can provide productive, yet efficient solutions.

With more than $70 billion committed by the Australian Government to transport-related infrastructure developments in its 2017-18 budget, the country’s sand and aggregates market is looking to a future rich in opportunities for go-getting operators that respond to demand with value for money and high quality products.

About 25 years of innovation, experience and satisfied clients have made CDE Global a preferred wet processing equipment company for an increasing number of sand and aggregates producers.

The company offers the local industry a customised service based on an in-depth understanding of the market, and proactive solutions adapted to each individual client’s specific requirements. From start-up companies to established sand and aggregates producers, CDE has provided more than 1000 turnkey wet processing solutions globally, including the largest sand and aggregates wet processing plant in the world in Qatar.

Why wash?

“With growing opportunities in the Australian sand and aggregates sector, operators are seeking more effective wet processing options to meet market demand in terms of quality, quantity and the range of available material gradings,” said Marius Snyman, CDE Global’s regional manager for Australia.

"The key to the success of CDE installations is in co-creation"

“Sand screw and bucket wheel systems have been around for a long time, but have proven to be less effective than hydrocyclone technology. Further, wet processing technology has moved forward considerably over the past few years.

“When using sand screws and bucket wheels, a substantial amount of fine usable product can be lost to ponds and the quality and consistency of the cut can be inferior, depending on the final product.

“The introduction of an efficient, reliable washing plant to an existing installation or a new site allows for a significant increase in production, reduced maintenance, reduced manpower, reduced slimes management and continuous operation with water control.

“CDE’s modular sand washing systems have been tried and tested in Australia by satisfied customers who opted for solutions that require a minimal amount of civils and provide consistent high quality sand and aggregates in any quantities. Fast return on investment, further boosted by energy and water savings, is also a key influencing factor when it comes to starting a new operation or upgrading an existing one.”

Water, slime management savings

A filter press, added to a thickener tank, can eliminate the need for tailings ponds.
A filter press, added to a thickener tank, can eliminate the need for tailings ponds.

The issue of water availability and water and tailings management is a primary focus for all quarries, mines and construction companies in Australia. Restrictions on water extraction from ground sources and rivers, as well as their associated environmental consequences, have made the recycling of process water a must for sand washing operators. The CDE AquaCycle thickener is a tried and tested addition to materials wet processing plants; because it can recycle up to 90 per cent of process water that is ready for immediate reuse in the system, it offers the added bonus of a small footprint and reduced environmental impact.

After the raw material has been washed and classified, process water containing fine material is sent to the AquaCycle thickener. In the AquaCycle, a small amount of polyelectrolyte flocculant is added to the water from the automatic dosing station that 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 water tank before being re-circulated back to the washing plant, helping to reduce the amount of required fresh water for top-up down to 10 per cent. The waste slime from the AquaCycle thickener is discharged to either a tailings pond or, to eliminate tailings ponds altogether, a buffer tank where the slime can be processed by means of a centrifuge or plate filter press.

This CDE water efficiency technology is user-friendly and requires minimum civils and the smallest equipment footprint. It is also designed for easy use and safe access for efficient maintenance and workers’ protection.

“Adding a CDE AquaCycle thickener to a wet processing plant to recycle up to 90 per cent of process water straight back into the system adds a significant edge to an operation, as it allows for significant water and energy savings on projects from low to high processing tonnages,” Snyman said.

Managing tailings ponds, slime

A close-up of the overflow weir on the AquaCycle A1500 thickener box.
A close-up of the overflow weir on the AquaCycle A1500 thickener box.

The environmental benefits of CDE’s high tech solutions are significant, to the point that customers can reduce fresh water requirements and eliminate tailings ponds if they wish.

A typical sand washing operation uses a minimum of 100,000 litres per hour, which is clean water being used to wash sand and aggregates; it is converted into waste water, then pumped or piped away into tailings ponds, at which point it exits the washing system. A CDE filter press or centrifuge solution, added to an AquaCycle thickener, eliminates the need for tailings ponds.

CDE Australia, working with a world-class engineering team, has delivered complete bespoke plant solutions in six states and territories in Australia in the past few years. These plant solutions cover tailings pond management and slime management in the sand and aggregates, industrial sands and mining sectors.

“The conventional use of settling ponds has various drawbacks, such as increased downtime while the material settles and the need for extra space on site to accommodate the ponds,” Snyman said.

“Stringent water restrictions should not be an impediment to operators who wish to benefit from the reboot of the Australian sand and aggregates industry.

“CDE’s water management technology, from water-efficient washing plants to full water recovery management systems, promises maximum production efficiency, minimum loss of fines and water savings. CDE’s water management systems not only minimise water consumption but also aid businesses in showing compliance when reapplying for water licences and tailings pond expansions.

“It is good news that many of our clients across Australia have already saved – and continue to save – high volumes of water, thanks to the range of tailor-made, high tech and simple to use products CDE offers. With 25 years of experience in supplying class leading wet processing solutions, the company has carved a reputation of excellence internationally, and our existing customers in Australia regularly become repeat clients as their production – and therefore business – grows thanks to their CDE installation. The future of washing is bright in Australia.”

Customer-centric approach

A 1-2mm medium sand stockpile after processing.
A 1-2mm medium sand stockpile after processing.

CDE’s approach to project delivery begins with extensive testing of representative feed material from the client’s site. It normally involves a range of feed gradings of various blends of fines and coarse material within the resource. The samples are then tested at the CDE laboratory facility in Northern Ireland and are used as the basis of the plant specification. A plant concept, resting on the client’s requirements and the production potential established from the sample analysis, is then developed and submitted to the customer.

According to Snyman, the key to the success of CDE installations is in co-creation – that is, CDE’s engineering and design teams work from the customer’s input to create a wet processing solution customised to their needs.

In the case of the CDE plant at Australian glass sand producer Earth Commodities, for example, the plant was configured to match very specific requirements for glass sand production and other sand fractions.

The plant incorporates several equipment options from the CDE core product range, including a M2500 mobile washing plant, multiple EvoWash sand washing plants, several prograde screens and an AquaCycle thickener. The system also includes bespoke equipment such as high frequency screens for glass sand separation and dewatering, spiral separators and counter flow classification units.

The material produced is clean, white, high silica sand that requires sizing and spiral classification to remove refractory particle contamination. The plant capacity is a 130 tonnes per hour (tph) feed rate and it produces 65 tph of glass sand, with six further sand fractions being turned out by the remaining tonnage.

The addition of wet processing equipment to the Earth Commodities plant has enabled the company to grow its capacity by up to five times, with the added bonus of producing various other size fractions on top of consistent, high quality glass sand.

Proman factor

For every plant CDE designs and deploys anywhere in the world, the ProMan system activates as soon as the customer places an order.

Applied by CDE to all its projects, ProMan entails the allocation of a project manager as the single point of contact for the client. Supported by a project team that covers all aspects of the work, the project manager accompanies the client from the conception of its bespoke washing installation to its commissioning, with responsibility to deliver the highest level of quality within agreed timeframes and costs.

With the added bonus of fully transparent and straightforward communications, the development, building and commissioning process becomes seamless.

CDE Global’s Australian office is in Ormeau, Queensland.

Source: CDE Global




















Monday, 20 August, 2018 03:04pm
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