07 December 2020
To maintain momentum and to support the continued progression of the industry, CDE, harnessing the global reach offered by digital conferencing, recently programmed its Engineering Insights symposium to deliver the tradeshow experience virtually.
Across two days from 14-15 October, CDE experts, together with a host of guests and industry figures, facilitated a series of dynamic, educational and informative presentations and panel discussions covering multiple sectors, including sand and aggregates, construction and demolition waste recycling, industrial sands, mining, and wastewater.
Discussing the challenges and considerations for water management in the region, CDE Business Development Manager Willem du Plooy was joined by JC Janse van Vuuren and Johan Meintjes from South African construction materials producer Ground Breakers.
In 2019, to fully achieve the sustainable and profitable vision of the company’s owners, CDE commissioned its Combo™ all-in-one wet processing and water management system at Ground Breakers’ quarry in Lanseria. The plant, which replaced an inefficient bucket wheel system, was designed to tackle the loss of valuable materials to ponds and excess moisture in the final products.
Commenting on the bucket wheel technology Willem du Plooy said, “Dewatering of your material was not very effective meaning you had wet stockpiles of sand that you were trying to market. With limited mining area, you had to relocate it to get it to dry and could not sell it immediately.”
The quarry was experiencing water stress, he added, however water was available. “You had it lying in your stockpiles,” he said.
In a region that is heavily regulated, Johan Meintjies says it’s difficult to get a water permit.
“Once you have received this,” he said, your usage is limited and “not sufficient to wash the sand” to industry requirements with inefficient technology.
“Your clients won’t buy it if it’s not dry enough,” he added.
Incorporated in the plant is CDE’s cutting-edge water management which ensures final products are dewatered to an average 12% moisture, making them ready for market straight from the belts. As an added benefit, the fully integrated CDE AquaCycle thickener allows for up to 90% of the process water to be recycled directly into the system for near independence from fresh water supplies.
Commenting on CDE’s AquaCycle, JC Janse van Vuuren explained how the water management solution has reduced the volumes used and saved water resources at the quarry.
“We don’t actually worry about it anymore,” he said, later adding, “The biggest difference is how much cleaner the water is in the process.”
Meintjies said the company aims to be as green as possible through its CDE Combo™, which is powered by sustainable all-electric drives and reduces water requirements.
“We see a big push towards sustainability within the industry,” he said.
Agreeing, Janse van Vuuren added, “We are one of the few companies who offer the more environmentally friendly option and we have seen an increase in sales as a result.”
Outlining the commercial advantages of adopting sustainable practices, du Plooy added that sustainable materials producers are in a stronger position to become the preferred supplier.
Discussing diamond recovery technologies, CDE’s Willem du Plooy was joined by Nico van Vuuren, Process Engineer at Consulmet.
Beginning the discussion, Willem du Plooy said, “If you look at the number of carats produced per year and the amount of turnover, there are two countries who own the lion share of this market: Botswana and Russia. Botswana produces fewer carats, although the value is much larger.”
Nico van Vuuren added, “South Africa and countries Lesotho produce smaller volumes but high revenue in terms of dollars per carat.”
Commenting on the challenges at the BK11 project in Botswana, van Vuuren said, “One of the first problems encountered with the first stage of operation was clay balls and clay that wasn’t broken down properly. They had two crushers and the material couldn’t get processed through the crushers”
He highlighted the importance of going “back to basics”.
“Why do we scrub? Obviously, we scrub to get rid of any clay material that is present in the ore. Diamonds will prefer to stick to any clay surface because they both have hydrophobic properties.
“So, breaking down the clay into a slurry phase is how we liberate the diamonds.”
Consulmet commissioned a CDE AggMax 83SR at the site for use in secondary scrubbing and vegetation removal of kimberlite.
Van Vuuren said, “When we started up, we were reprocessing a lot of the material that was just bypassed from the crushers previously.
“It went through a rotary barrel scrubber and the logwasher was a secondary scrubbing process. The material was cleaned extremely well.”
Removing vegetation was one of the advantages of the CDE logwasher, he explained, and is of critical importance for XRTs.
“The XRTs that we use to separate material is based on its atomic number. As a result XRT’s will eject all other carbonaceous materials with the diamonds. This includes vegetation and plastics that are present in the ore This leads to downstream problems on your XRTs like blockages.”
Sand Washing Challenges
CDE Regional Manager Ruchin Garg was joined by Ali Ahmed Al Theeb, General Manager at Sandco, to discuss how CDE hydrocyclone technology can overcome sand washing challenges.
“Older technologies have limitations when it comes to the loss of sand due to overflow,” Ruchin Garg explained.
“You lose a good amount of particles into the sludge. It requires a larger footprint, higher maintenance and availability of these machines in terms of downtime is much higher.”
“Typically, we see anywhere from 10-30% of material lost in sludge pits using a combination screw/classifier or bucket wheel,” he said, adding that CDE provides a solution with filter press and thickeners.
Ali Ahmed Al Theeb said, “In Kuwait, sand has a high amount of silt and fine content, almost 15-20%. It is a huge challenge to try and reduce this amount of silt.”
The high amount of silt content in the natural sand means it is unsuitable for construction and means sand washing is necessary.
“Until 2008,” he said, “we were using traditional technologies for sand washing, which depended on gravity for the separation process.”
“Traditional methods were so limited in terms of productivity,” he said. Adding that fine content still existed after washing, how waste of raw material was high and the high cost of water loss in stockpiles and sludge.
In 2005, the needs of the market changed. Many construction projects came up that required high strength concrete requiring high quality components, including washed sand.
“We started exploring alternative technologies for sand processing” to improve the quality of SandCo’s washed sands, he explained. After researching options, SandCo opted for CDE hydrocyclone and dewatering technology. "This technology was totally new to the Kuwait market,” he added.
Today, SandCo produces high quality sand to industry specifications with increased productivity and efficiency.
“Fine content now is under control…moisture content in the product is low,” Ahmed Al Theeb explained.
SandCo is now a certified supplier for many projects, producing premium washed sand and supplying the greatest market share of construction sand in Kuwait.
Ruchin Garg, CDE’s Regional Manager in the Middle East and Africa, was joined by Eunan Kelly, Head of C&D Waste Recycling at CDE, and Ahmed Taher, General Manager at Al Dhafra Recycling Industries LLC, to discuss the role of construction, demolition and excavation waste material in the sustainable city agenda.
At the outset of the discussion, Eunan Kelly asked, “What do we need to do next in order to get the innovative processes which we have a lot of confidence…to hit sustainable development goals number 11 and 12?”
Ahmed Taher said, “Mandating usage of recycled products supports the vision of the UN Sustainable Development Goals.”
“One of the key features that’s making us successful in Abu Dhabi and UAE is that it’s by law a minimum of 40% on each and every infrastructure project must use recycled products.”
Ruchin Garg agreed, “Legislation will make the business idea more feasible.”
Referencing landfills in Dubai, Kelly said there is a need for legislation but also behavioural changes.
“Legislation will drive usage, but a behaviour change is needed…we need to have a logical approach to how we use the material.”
Taher agreed, “You change the mindset, teach people how to recycle and reuse instead of using the virgin quarried material.”
Garg highlighted three key strands: legislation, technology and keenness.
“We have shown keenness, definitely. There is an appreciation of technology also…legislation is moving. There is a green bill in discussion.”
The packed two-day programme featured almost 90 sessions involving over 100 speakers. CDE’s Ruchin Garg says: “In these unique and challenging times there are many restrictions that have prevented CDE, our customers, and others in materials processing from coming together at industry events to discuss the prevalent issues of the day and the latest technological advances.
“Utilising our global network, we decided to programme the major two-day Engineering Insights symposium which proved to be a huge success with almost 1,500 industry professionals from around the world registering.
“We firmly believe this shared approach to knowledge and expertise is a better way to aid the progression of the industry.”
He says it is important to ensure these discussions can continue even though the industry is unable to come together in the same space.
“The challenges facing our industry – sand depletion, water management, sustainable mining and much more – have not gone away. As an industry leader in these fields we felt a responsibility to convene the very best in the business to facilitate these important conversations.”