Highly efficient pre-screening for higher crusher throughput and operating lower costPublished 9/3, 2021 at 15:34
Crushers can be used to crush a huge selection of materials, covering a wide range of applications, from recycling to natural stone. Often the crusher is fed with a high proportion of fine material, which unnecessarily passes through the crushing process, increasing wear and energy consumption while reducing throughput.
As a remedy, a bar mesh is normally used for pre-screening. However, if the fine material is damp and cohesive, it can quickly clog up the mesh screen and ends up passing through the crusher anyway. To counter this, Rubble Master has launched the patented RM ‘Active Grid’, a new highly efficient pre-screen that increases material throughput by up to 30% and reduces wear.
C&D waste, concrete rubble, asphalt, wall and river gravel are just a few examples where a high proportion of fine particles can be found in the feed material. If a pre-screening system is not used, all the material ends up in the crusher, irrespective of particle size, often passing through the whole crushing process. Unfortunately, the fine material causes unnecessary wear to the hammers, impact plates and wear plates in the crushing box, as well as higher energy consumption in the form of diesel or electricity, as the rotor is subjected to higher stress. The result is higher running costs as the hammers and wear plates need to be replaced more frequently, and maintenance cycles are shorter. This not only reduces the efficiency of the crusher, but also reduces profit, because material throughput is lower, but running costs are higher.
Conventional bar mesh
In many cases a bar mesh is used for pre-screening the fine material and small particles. So far so good, except that the bar mesh has the disadvantage that due to its rigid construction it clogs up over time, especially with damp, sticky or loamy, cohesive material, which reduces pre-screening efficiency. Even with dry material, the screening rate is often not ideal. This again causes most of the material to enter the crushing box, or block the inlet to the crushing box, slowing down the flow of material. This has the effect of reducing crusher throughput, increasing wear and requiring the crusher to stop so that the bar mesh can be cleaned.
Patented RM Active Grid
Rubble Master developed the RM Active Grid to solve the problems described above. It consists of rigid and movable sections of bar mesh that feature a special configuration. The vibration of the vibro- channel causes the Active Grid to oscillate, so it does not need its own drive system. The active vibration of one section of the bar mesh significantly increases screening performance and, depending on the material and the type of job, increases the total material throughput by up to 30%. Efficiency is also increased thanks to the self-cleaning effect of the Active Grid, ensuring consistent screening performance. The fine material can then bypass the crushing box onto the main discharge belt, or be discharged on a side discharge belt.
The result is more material throughput, less wear, lower costs and longer maintenance intervals, which ultimately adds up to more productivity and profitability. If pre-screening is not required because the crusher is being used for a different application, the RM Active Grid can also be fitted with a subfloor, which is quickly installed. The RM Active Grid is available for RM 100GO! and RM 120X crushers.
Just one pre-screen and scalper options
Because processing requirements vary greatly from one job to another, Rubble Master offers a range of solutions for pre-screening. In addition to the RM Active Grid and a standard bar mesh, a two deck pre-screen integrated into the feed belt is also offered for defined feed material particle sizes. RM also offers the HS series of mobile pre-screens, which are available in a range of sizes.