A perfect match: high resilience rubber screens and anti-blinding rods
The quarry of Riuma Mining is an automated plant and is part of a complex that includes, among others, an asphalt and concrete factory and Riuma Ambiental responsible for a landfill of Inertes that performs RCC recycling.
Automatized and designed for a nominal capacity of 500 tons per hour of mineral aggregates with a particle size of less than 21mm, the unit faced the challenge of an above average presence of fine contaminants. The quarry, however, was running at a production level of 300 tons per hour. The reason for the low performance was simple: the increased moisture was causing the material to clog the screens, hamper production, and adversely impact the quality of aggregates delivered. Today, six months after introducing Metso’s solution, the problems are solved.
The turnaround at Riuma involved a lot of changes. The main change was the adoption of rubber screening media from Metso, complemented by the use of Anti-blinding rods, a device already used in the fertilizer market, but not commonly used in the aggregates industry. The combination created a perfect solution: it prevents the holes on the screens from clogging, reduces the level of contamination of fines, and stabilizes the production. In the process, Riuma installed 180 rubber screening media panels in their deck and evaluated the performance when Anti-blinding rods were also used, especially during rainy seasons when there is a bigger problem with moisture in the feed material.
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Reduced energy consumption, reduced presence of contaminants
In addition to the productivity drop, manual intervention to clean the screens was required. This hazardous process created a bottleneck and exposed the operator to risks. By changing to the new rubber screening media, positive impacts were also introduced. In the past, the wear life of the competitor screening media was five months; now with Metso, the wear life exceeds 12 months. After more than one year of operation, only 14 of the 180 installed panels have been changed.
The impact of installing the new screening media can be measured in three ways, according to Marcelo Vinhal de Castro, Director of Mining of Riuma. “After a year of installation, our first gain was a 5% to 10% reduction in production costs. The second win was the 10% reduction in energy consumption. The third gain was the 20% to 30% improvement in the quality of the aggregates produced.
With the recent developments in the plant, we are part of the few quarries that can meet the level of quality required in major works of infrastructure and in complex processes such as the production of asphalt," says Marcelo Vinhal de Castro.
Optimization continued with the evaluation of the screen Anti-blinding rods
“Since installing the new rubber screening media, the blinding has been drastically reduced. But in periods of heavy rain, we were still having a decrease in production because of the humidity; that’s when we found another solution to improve the process, the Anti-blinding rods from Metso,” explains Marcelo Vinhal. Anti-blinding rods are devices that are used in the fertilizer market, but not commonly used in aggregates plants. After testing for five months, their efficiency in reducing the clogging of the screen holes was confirmed.
And more than that: The field experience has given Metso's engineering the ability to improve the device. "We developed rounded ends, which decreases the punctual wear caused by the edge of the cylinders, increasing the wear life of the accessory and the screening panel. The solution was so effective that we will also apply it in the area of fertilizers, which has used the Anti-blinding rods for many years,” explains André Rosa, Support Engineer from Metso.
Key initiatives: Changing the layout of the quarry, expanding the screening area and automation
According to Marcelo Vinhal, the improvements achieved with the use of rubber screening media are another example of a partnership between Riuma and Metso. He lists three initiatives – changing the layout of the quarry, expanding the screening area and automation. “Our plant was automated in 2013 and designed to achieve production of 500 t/h. The efficiency of the project is demonstrated by the results that indicate production of almost 600 t/h,” explains Vinhal.
André Rosa, from Metso, also highlights the importance of the partnership on the successful use of rubber screening media. “Riuma also helped us by sharing production and process data, laboratory testing and even making a production stop for the screens to collect and analyze information,” he explains. According to him, the data collected allowed Metso to deliver a better solution, with a positive impact on the productivity and quality of the aggregates.
Maria Theresa Musel, Technical Seller from Metso, notes that the contamination problems Riuma experienced are common in quarries and highlights the importance of customized solutions. "To help our customers, we provide specialized technical assistance to identify the ideal application, and we propose product solutions that will make the difference in the day by day operation. This is exactly what was done for Riuma with a design involving original Metso self-cleaning rubber screening media.
Sustainability on the agenda
In addition to supplying to external customers, Riuma Ambiental allocates a significant part of its production to the group's projects, such as the Usicity asphalt plant, located on the land next to the quarry. "With the recent developments in the plant, we are one of the few quarries that meet the level of quality required in large works and complex processes such as asphalt production," says Marcelo Vinhal.
Servicing clients around the quarry allows Riuma to be more sustainable and has an environmental advantage, causing the company to eliminate CO2 emissions as it reduces the circulation of the trucks. "In addition to sustainable logistics, we also have an environmental compensation program through which we have already recovered the equivalent of 15% of the area of the project and we have the goal of reaching 20% by the end of 2021," he says.