Kayasand’s aggregate washing plants are not only waterless, but they also bring multiple savings and environmental benefits.
For many quarries, high water usage and the associated hassle of processing the runoff are seen as unavoidable parts of the process.
The team at Kayasand is chasing a vision of enabling quarries to “turn off the water” by producing clean aggregates, using a novel dry processing technology.
Water management is a growing concern for quarries as they adapt to changing legislation around water management, coupled with more extreme dry and wet periods.
Kayasand offers waterless options for washing aggregate, from the four deck RCAS range of screens to the V7 sand manufacturing plants. RCAS screens are an alternative tertiary screening process to sort and de-dust coarse aggregates for concrete and asphalt. The V7 sand manufacturing plants shape and grade crusher dust to produce the “perfect” concrete sand (Kayasand) in a single process.
Talking through Kayasand’s novel method of washing sand, the company’s national sales manager Frank Grech spoke on the benefits of waterless wash plants for the quarrying and aggregate industries.
“Cleaning sand and aggregates for concrete and asphalt uses a process that, in many cases, has traditionally required water. Yet water is increasingly becoming a limiting resource, especially in Australia where consistent access can be a challenge, and its availability drastically impacted by environmental conditions,” Grech said.
In extreme cases, he noted reliance on water for washing aggregates can cause quarries to temporarily shut down during draught periods.
There are also hidden costs that come with water management, he explained. “These vary from one quarry to another, depending on the water quality and the water management solutions they use, as well as their environmental conditions.”
“With Kayasand technology, we offer options for blending water with the final product. But there is no need to use water when making it,” he said.
“One of the big selling points of the V7 plants is that you don’t need a water management system in place other than for such activities as washing down. All you need is the raw material,.”
Due to the fully enclosed nature of the V7 plants, an installation also limits unnecessary exposure to dust. The negative pressure of the machinery, from the built-in dust extractor, keeps dust contained and away from operators.
“The plant takes out the good dust and fines that may otherwise be lost as silt in the washing process, and turns them into a usable product,” Grech said.
“Through repurposing dust and other materials which would otherwise be wasted in the process, we can reduce the environmental impact and also provide the quarry with more saleable products.”
According to Grech, the adoption of the waterless wash plants worldwide is growing. Not surprisingly, so are the number of quarries producing manufactured sand.
The V7 plants produce a unique manufactured sand, known as Kayasand, with clear benefits in concrete production.
“One of the advantages of Kayasand is that it takes a low value crusher dust and manufactures a concrete sand to the customer’s required specification in terms of shape, grading and consistency,” Grech said. “This allows the consistent production of a concrete with consistent predetermined performance.”
With a pathway to net zero emissions for carbon in concrete by 2050 set out by the Cement Concrete and Aggregates Australia, a key change in the value chain is the improvement of the mix design for concrete. This can be achieved by optimising the packing density of concrete.
According to Grech, the equipment provided by Kayasand directly improves the design mix of concrete, because it precisely shapes and screens sand during processing.
“The V7 plants can facilitate better packing density by including concrete-suitable materials throughout the entire product curve,” Grech said. “This enables manufacturers to optimise the packing density of their concrete to require less cement in the finished product, resulting in a lower-emission concrete.”
This has implications beyond just the quarrying industry, particularly as pressure mounts on the wider aggregates and construction industry to reduce their CO2 emissions.
“At many of the V7 plants installed across Asia, the manufactured sand product is used as a 100 per cent replacement for the natural sand in concrete,” Grech said.
He used an example to demonstrate the savings.
“Mix designs vary, but assuming you have 860 kilograms of sand per cubic metre of concrete, and a 100 per cent replacement of natural sand with Kayasand, a V7-240 Kayasand plant producing 600,000 tonnes per year produces enough sand for 700,000 cubic metres of concrete annually. Dependent on the plant and the material being processed, the V7 plants can process a nominal 240 tonnes of material per hour.”
The technology used by Kayasand was first developed by Kemco in Japan. There are now 320 plants operating across Asia. The growth is driven by changing regulations and availability of natural sand, with about 40 built in the last 12 months.
“The plants are not just benefiting the environment, but also the quarries themselves,” Grech said
The Kayasand V7 plants give operators the ability to grade material and receive a consistently shaped end product, even with varying feed consistency.
“Water is not the only way,” Grech said. “New processes are now available that enable quarries to turn off the water, while at the same time reducing waste and producing a higher quality end product with great sustainability credentials.” •