The high-pressure grinding rolls from Metso are helping quarries deliver high-quality sand and aggregates to the market.
Access to natural sand reserves has become more complicated in certain regions, and other areas are seeing their reserves become exhausted.
For customers looking to develop high-quality sand or work with complex feed materials, Metso has developed the HRC 8 and HRC 800.
Featuring a simple and robust design, the HRC 8 and HRC 800 provide a low cost of operation and improved product shape and grading.
Designed to work in challenging applications, the machines allow operators to turn waste products into sellable materials. These applications range from feed materials with low crushability to materials with high moisture, including clays, without overloading the crusher.
“These machines are suitable for specific applications where materials that are waste from the crushing and screening process can be reprocessed to obtain good high-quality sellable products. HRC 8 and HRC 800 produce the highest quality products with improved shape and relatively low energy and wear parts consumption with the lowest possible cost per tonne,” Metso said.
At the heart of the design for the HRC 8 and HRC 800 is the high-pressure grinding rolls (HPGR) technology, which is optimised for manufactured sand.
The robust HPGR technology compresses the material between two rotating rollers, one in a fixed position and one in a floating position. Together, the rollers generate a high pressure, which crushes the feed material into the desired size.
The operator can adjust the speed and pressure from the HRC to suit the material conditions and application. The pressure control allows the operator to adjust the reduction ratio, while the speed control ensures the throughput can be tailored to the operation.
According to Metso’s internal testing, the HRC 8 and HRC 800 can use up to 50 per cent less power in sand production than other equipment for the same net product.
The industry-tested machines have delivered impressive performance in real-world applications. One Metso customer in Mexico wanted to increase their sand production by repurposing some of their on-site, unsellable waste product.
By re-crushing 19mm and 12mm gravel rock and increasing the asphalt sand fines content to a minimum of 15 per cent, the customer was able to deliver a quality sand product that saved them from buying it from competitors.
The HRC 8 was added to the circuit for a demonstration, using 19mm top rock from their stockpile. The customer was able to adjust the machine parameters to suit their needs. With 60 per cent less than 16 mm on feed, which was very clean with no fines below less than 15 mm, they recirculated +6 to -9 mm rock with an ST 3.8 double-deck screen, which helped to increase sand production.
“HRC 8 process adjustable to customer’s sands needs, quality and production volume, it depends on the combinations of the crusher setting parameters. Not too many parameter options can be adjusted to control the ultra-fines production, this characteristic depends more on the feed material properties, but with the wide range of operating pressures, the HRC technology is the best option for those requirements,” Metso said.
This is where the HRC 8 and HRC 800, with their strengths in product shaping, product gradation, and fine production, can play a key role in the production of manufactured sand.
“HRC 8 and HRC 800 deliver a perfectly cubical shape for concrete and asphalt sands,” Metso said.
“They also produce more fines with fewer unwanted microfines in the final product compared to other technologies in manufactured sand.
“HRC 8 and HRC 800 are particularly productive in producing manufactured sand for asphalt and concrete production. The quality of manufactured sand can be adjusted and optimised, which reduces the amount of cement and asphalt in the mix of concrete or asphalt.”
The HRC 8 and HRC 800 are made to last the distance with their HRC grinding rolls and components, which are known for their robust design and longevity.
Metso has designed the machines to prioritise safe and easy maintenance to reduce downtime. The patented split shaft in the HRC allows wear parts to be changed easily without disassembling the machine. The anti-skewing arch frame ensures bearings are protected from misalignment, which saves maintenance time.
This is supported by the Metso global distribution and logistics network, which ensures that its original equipment manufacturer spare and wear parts are available when customers need them. Whether it is a standard or engineered-to-order part, Metso’s network can provide it.
They can be equipped with Metso crusher automation, which controls and monitors the crusher and ancillary equipment via a remote control. The crusher automation is a complete package that includes fully automated hydraulic circuit controls, hydraulic unit motor starters, and electrical cabinets.
“Crushing optimisation helps to provide constant throughput at all times. IC crusher automation provides instant process information to the operator. The automatic feed rate control helps to maintain the optimal material level in the crusher, which helps you to achieve and maintain the best performance at all times. The whole system is not just easy to install and commission; it’s easy to use, too,” Metso said. •
For more information, visit metso.com
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