Mobile crushers
The concept of a mobile crushing unit is nothing new to mining professionals. However, its use has only become more widespread in recent years, due to advances in related areas of engineering. When compared to stationary systems that rely on off-road truck transportation, mobile crushers have significant advantages, the main ones being [1]:
- Cost reduction;
- Reduction in the workforce required for the operation;
- Reduced fuel consumption;
- Decrease inCO2 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]
With the change in nominal and design production capacities, the variation in the mass flow rate and operating speed of the conveyors in the machines has a direct impact on the behavior of the material in the receiving and unloading chutes of the mine machines.
A Kot foi responsável por diversos trabalhos nesse sistema de britagem móvel. Este artigo tem como objetivo dissertar sobre a verificação do alimentador de recebimento e de um chute intermediário de transferência de minério da unidade, por meio de simulações do método dos elementos discretos (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.
Figures 2 and 3 show some of the models 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.
The purpose of the characterization is to identify material properties that are input parameters for the simulations in the specific DEM analysis software (particle-particle and particle-chute wall interaction properties). The tests also 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]
The DEM analysis of the feeder indicated the equipment's operating speeds for some of the different material conditions that are processed by the equipment, and a suitable type of operation is indicated for each material variation handled.
As a result, the values obtained are in line with the proposal to repower 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]
The simulations with the repowered design showed that the chute could not handle the increased capacity of the conveyors for the operating conditions, since problems related to clogging were identified. The component was therefore redesigned.
With regard to the loads on the impact table, it was found that the rollers in this area are able to operate under the new capacity. In addition, the analysis indicated that the plate identified as a deflector does not receive impacts from 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.
De forma geral, a Kot pode auxiliar na realização de análises computacionais e levantamentos de campo. A empresa pode atuar em diversos setores da indústria, desde o de celulose até o de mineração, trazendo soluções adequadas para suas necessidades. Consulte também nossa equipe para mais informações!
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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
