Wirtgen: Flexibility, Precision Guarantee the Right Material Size

Compliance with the required material size is a decisive factor for ensuring efficient processes in opencast mining operations. With the Vario Impact Sizer (VIS), Wirtgen offers a system that scores top marks in terms of flexibility, precision and adaptability, according to Wirtgen.

It enables machine operators to reliably control the maximum particle size and particle size distribution, even under constantly changing operating conditions. Extensive evaluation of the system in practice has confirmed its effectiveness, particularly in coal and bauxite mining operations.

Selectable Settings

The core of the VIS is a split baffle plate mounted directly on the cutting drum housing. This plate is equipped with two primary adjustment mechanisms that enable precise control of the material that passes through the system, according to Wirtgen. The variable gap between the plate and the cutting drum is the first adjustment mechanism: this distance can be adjusted in five stages to control the amount of additional crushing and thus change the particle size.

A smaller gap results in extra crushing and thus finer material, while a larger gap results in coarser material. The adjustment is made by simply enlarging or reducing the gap and securing the plate with pins, which takes around ten minutes. The second adjustment mechanism relates to the holes in the scraper. Depending on the specific requirements of the operation, they can be opened or closed in four different settings by means of covers.

These two mechanisms complement the basic adjustment options of the Surface Miner like the advance speed of the machine, the speed of the cutting drum, and the cutting depth. In combination with the VIS, this results in an extremely high level of control over the maximum particle size.

Vario Impact Sizer

Machines in cut-to-ground or windrow applications often produce material that exceeds the required maximum particle size. This is where the VIS comes in — the system is designed to fulfill precisely this requirement by influencing and limiting the maximum particle size. Finer material passes through the sizer and leaves the crushing process while coarser material is crushed until it can also pass the sizer.

The VIS has proven itself in both coal and bauxite mining applications and effectively controls the size of the material produced to ensure that it meets the specified requirements, according to Wirtgen. One of the advantages of the VIS is its seamless integration into the machine. The VIS is mounted directly on the cutting drum housing and integrates seamlessly into the material processing process. Furthermore, the system is highly adaptable.

The variable settings enable reliable crushing of a wide range of rocks and minerals. The VIS is particularly suitable for brittle and porous rocks and minerals such as coal, bauxite or chalk, according to Wirtgen. The construction of the VIS ensures that it can withstand the harsh conditions in mining and meets all requirements for durability and stability, even at high throughput rates.

Use in Opencast Mining

The VIS is available for the 220 SM(i) 3.8. Particle size control is achieved through the interaction of standard machine settings and the VIS settings. The standard machine settings include the machine's advance speed from 0 to 275 ft. per min. The cutting drum speed also is adjustable with six standard settings on board.

The cutting depth is adjustable from of 0 to 13.8 in. The settings of the VIS consist of the five baffle plate gap settings from 0.86 in. to fully open and the four cover plate opening settings, which can be adjusted from fully closed to fully open. This wide range of combinations offers almost unlimited possibilities for influencing the maximum particle size and the particle size distribution, according to Wirtgen.

Practical Examples From Coal, Bauxite Mining Applications

In the meantime, the performance of the VIS has been evaluated in various mining regions. In coal mining in India, the system showed improvements in the control of coal particle size. Specific settings were used to achieve a target size of less than 3.9 in. In bauxite mining, the VIS delivered impressive results in the Boffa and Boké regions of Guinea.

During mining in Boffa, the sizer was opened fully to enable a cutting depth of 11.8 in. and a high advance speed, enabling maximum performance for the achievement of high productivity. In Boké, the settings were adjusted to a material size of less than 3.9 in., demonstrating the system's ability to adapt to different types of bauxite and different crushing behaviors. Clearly noticeable in practice: the settings have to be carefully adapted to the requirements since additional crushing reduces the throughput rate.

Assists Operators

The VIS provides machine operators with a tool that gives them precise control over the maximum particle size, according to Wirtgen. The system settings have a direct impact on key performance parameters: particle size distribution, production output, fuel consumption, tool wear and stress on parts and components.

By specifically adjusting the configuration, the operator can always achieve an optimal balance between material requirements, process stability and overall cost-efficiency. The VIS thus confirms its role as an effective tool for efficient material size control in contemporary opencast mining scenarios.

For more information, visit wirtgen-group.com.