DEM analysis in mobile crushing has become an important tool for evaluating ore flow and optimizing operations in mining systems. With that in mind, keep reading to learn how DEM simulations have helped with the operational evaluation of the mobile crushing unit.

 

Mobile crushers

The concept of a mobile crushing plant is nothing new to professionals in the mining industry. However, its use has only become more widespread in recent years, thanks to advances in related fields of engineering. When compared to stationary systems that rely on off-road trucks for transport, mobile crushers offer significant advantages, the main ones being [1]:

 

• • Cost reduction;

• • Reduction in the workforce required for the operation;

• • Reduced fuel consumption;

• • Decrease in_CO2 emission levels.

With a view to competitive ore production, combined with more sustainable, modern solutions and without the use of off-road trucks to transport materials, one of Kot's customers wanted to upgrade the nominal and design capacities of one of its mobile crushing units from 9,500 to 10,500 and 11,500 to 12,600 tons per hour respectively. This system can be seen in Figure 1.

Figure 1: General view of the mobile crushing system in question. [2]

Consequently, given the changes in nominal and design production capacities, variations in the mass flow rate and operating speed of the conveyors in the machines directly affect the behavior of the material in the feed and discharge chutes of the mining machines.

Kot was responsible for several projects involving this mobile crushing system. This article aims to discuss the verification of the receiving feeder and an intermediate ore transfer chute at the unit, using simulations of the discrete element method (DEM).

Three-dimensional modeling

Starting work, the first stage of development for the discrete element analysis was to draw up three-dimensional models of the feeder and the intermediate material transfer chute. 

As these are models of material flow surfaces, details such as inspection doors and windows and other auxiliary devices were not modeled. These components are generally not considered in the analysis, as they do not significantly influence the flow of material in the structure. 

For example, Figures 2 and 3 show some of the models that were developed.

Figure 2: Three-dimensional model of the feeder. [2]

Figure 3: Three-dimensional model of the intermediate kick. [2]

Analysis

Some of the main analyses carried out using the discrete element method for the mobile crushing plant are shown below.

 

• • Material

Kot received characterization tests on the material being transported and calibrated the material model based on its characteristics. 

In this regard, the characterization aims to determine the material properties that serve as input parameters for simulations in specific DEM analysis software (particle-particle and particle-chute wall interaction properties). In addition, the tests help to understand the flow of the ore stream.

 

• • Feeder

Figure 4 shows the overview and central plan of the DEM model generated for the feeder.

Figure 4: General view on the left and central plan on the right of the DEM model of the feeder. [2]

Consequently, the DEM analysis of the feeder identified the equipment’s operating speeds for some of the various material conditions processed by the equipment, with a suitable operating mode specified for each variation in the material handled. 

Thus, the values obtained are consistent with the proposal to upgrade the mobile crushing unit and serve as a reference for operating the equipment.

 

• • Intermediate kick

Figure 5 shows the clogging analysis of the intermediate chute of the mobile crushing unit.

Figure 5: Fouling analysis of the intermediate chute. [2]

However, simulations of the upgraded design showed that the chute could not accommodate the increased conveyor capacity under operating conditions, as clogging issues were identified. For this reason, it was recommended that the component be redesigned.

With regard to the loads on the impact table, it was found that the rollers in that area are capable of operating at the new capacity. Furthermore, the analysis indicated that the plate identified as a deflector is not impacted by the material flow.

Simulations vs. real conditions

The spread of computational techniques has led to both the refinement of the methodologies for their execution and the acceptance of the results obtained through them. However, even today, simulated results that visually portray real operating conditions are still highly regarded by engineers and managers.

In this respect, Video 1 shows a comparison of footage of the operation of the feeder of the mobile crushing unit in question with the result of its DEM analysis.

Video 1: Comparison between the operating conditions and the result of the DEM simulation of the feeder. [2]

Conclusion

Computer simulations can either be supplemented with information collected in the field during operation, or endorsed by comparison with real conditions that exhibit great similarities. 

In short, Kot can assist with computational analyses and field surveys. The company serves a wide range of industries, from pulp and paper to mining, providing solutions tailored to your needs. Please also contact our team for more information!

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References:

[1] DEAN, M. et al. Selection and planning of fully mobile in-pit crusher and conveyor systems for deep open pit metalliferous applications. In: AusIMM 2015 3rd International Future Mining Conference, Sydney, NSW, Australia. 2015. p. 4-6.

[2] Kot Collection