CDE Global has seen an increase in demand for its highly efficient sand-washing equipment, which addresses the key disadvantages of traditional units in the region – namely the quality of the product, the loss of quality fines, and operational costs.

The Northern Ireland-based manufacturer of washing equipment for quarrying, mining and recycling has built a reputation for delivering efficient sand-washing plants throughout the world over the last two decades and has been working in the Gulf for almost 10 years.

During this time, the company has completed many sand-washing installations including two 1,200-tonne-per-hour (tph) plants in Qatar. There are numerous other CDE washing plants in operation in many other regions of the Gulf and North Africa including Saudi Arabia, Oman, Bahrain, Tunisia and Morocco.

“Our entry into the Gulf came as a result of the demand for high-quality washed sands in the region,” says Iain Walker, CDE sales manager for the Middle East and North Africa (Mena) region.

“This resulted in the two large 1,200-tph projects in Qatar initially and since then there have been many other installations with capacities more in line with everyday requirements – between 50 and 150 tph.”

The Sirocco air classification plant with hopper and conveyors.

Washing is widely accepted to be the most efficient way of producing high-quality sand for a variety of applications, ranging from use in concrete to specialist applications such as golf and silica sands. “This is because of limitations with traditional dry screening processes particularly in regard to the ability of these systems to effectively and consistently remove minus-75 micron material,” Walker points out.

Over the years, CDE has developed a project list full of examples of replacing inefficient traditional sand-washing plants such as bucket wheels and screw classifiers with the hydrocyclone-based Evowash system.

“Old sand-washing technology has a number of issues, not least the loss of significant quantities of quality fines to the settling ponds or water treatment phase,” says Walker. “In an effort to ensure effective removal of the minus-75 micron fraction, these inefficient systems take a lot of commercial quality sand with them, which has a negative impact on the profitability of the operation.”

According to CDE, operators using inefficient sand-washing plants are taking a hit on two fronts. Not only is the final value of their sand product compromised by the presence of larger quantities of minus-75 micron material than is ideally the case, but operational costs are also increased as a result of the requirement to clean out settling ponds regularly in an effort to recover the good material that has been lost, Walker says.

There are various design features on the Evowash plant that prevent this problem from arising, with the choice of hydrocyclone technology being one of the key factors, he points out. “Hydrocyclones offer the most efficient means of delivering the required cut point thus ensuring a sand product that meets the desired specification. Being able to guarantee a sand specification maximises the commercial value of the material and thus the profitability of the operation.
“Investing in low-cost, old technology is a false economy as the return on investment takes much longer than is the case when our washing system is specified,” says Walker.

In addition, CDE’s ability to offer operators water recycling equipment to accompany the sand-washing plant has also been a key factor in the success that the company has enjoyed in the Gulf.

Given the climate in the region and a scarcity of water when compared to the North European markets where CDE originally established a reputation, the specification of the Aquacycle thickeners and GHT filter presses that CDE offers was very frequent as business grew.

“You could say that Gulf operators led the way for the global washing industry in relation to the specification of water recycling equipment,” says Walker. “We would now include our thickeners and filter presses on 80 per cent of all global washing projects whereas as recently as five years ago, this figure would only have been around 20 per cent.”

The scarcity of water in the Gulf was a major factor here and made the CDE water recycling and sludge management system a ‘must have’ rather than a ‘like to have’ as it was seen in some other territories. Environmental concerns and subsequent legislation in this area has driven demand for water recycling systems but there is also a growing realisation that their introduction does actually offer a more efficient way of operating.

According to CDE, when the costs of managing large settling ponds are factored in, the additional space required to accommodate the operation and the potential health and safety risks, water recycling systems offer operators a way to ensure a much more efficient and easily managed washing plant.

Dry processing
Just as the introduction of effective water recycling systems was a response to the unique climate of the Gulf region, CDE then introduced new air classification technology.

“The introduction of our Sirocco air classification system was a move inspired by the need to offer a solution to operators not able to consider a washing plant due to water supply issues,” says Walker. “Even with full closed-circuit water recycling reducing the volume of fresh wash water required to around five per cent of the total volume, some operators are simply not able to ensure supply of the volumes needed to operate a wash plant.”

Although dry screening of material is considered to be not as efficient a process as washing, Walker says Sirocco air classification system – although a dry process – is far removed from the traditional methods, which have been problematic for those seeking to produce high-quality sand.

“The key success of washing using our Evowash system is the capability to efficiently remove the minus-75 micron material,” he says. “We prefer to describe the Sirocco as a dry wash system – or washing without water as it is able to achieve the same results as washing in terms of minus-75 micron fines removal.”

Prior to the introduction of the Sirocco air classifier to the Gulf, operators wishing to produce quality washed sands were unable to do so because of a lack of water availability.

The introduction of Sirocco has made it possible for these operators to achieve the higher specification sand products that will allow them to diversify into new sectors of the construction market.

 “We have several Sirocco units operating in Saudi Arabia and Oman, which are producing concrete sands to the same specification as those being produced by our Evowash sand-washing plant,” says Walker. “With each new Sirocco unit comes a growing acceptance of the technology and a realisation that this dry wash system is a viable alternative to a washing plant.”

An additional feature of the Sirocco system that has made it attractive to operators is the small amount of space required to accommodate the system. CDE offers the Sirocco as a stand-alone unit or as part of a turnkey package. The turnkey option includes a feed system, the Sirocco air classification unit, two stockpile conveyors – one for the sand product and one for the fines – and a dust suppression system. The fine product from the Sirocco is not a waste material but has a number of applications including its use in the manufacture of ceramic tile adhesives and grouts. This provides additional revenue for operators from what many consider to be a waste material.

The Sirocco system is available in a variety of configurations from 50 tph to 800 tph in a single unit. This differentiates the Sirocco from other air classification systems on the market that offer single units at 150 tph and multiples of this system should larger capacities be required.

“Our washing plants are customised to the specific requirements of each project and our Sirocco units are built according to the same principles,” says Walker. “The specification of the right system needs to take into account the individual characteristics of the feed material, with the level of fines being the critical factor. Other systems take a ‘one size fits all’ approach, which compromises final product quality.”

With the suite of products developed by CDE, the company is confident of further growth in business during the months and years to come.

“The introduction of the Evowash and Sirocco units reflects the approach we take to all the regions in which we operate. We will continue to respond to the specific requirements of the Gulf region as we seek to continue to offer operators the most efficient sand processing systems available,” concludes Walker.