Discrete Element Method for better Mining Operations

The mining and mineral processing industry operate in a very high tonnage range which makes the equipment more prone to damage and wear. This also means that testing new designs at plant scale would lead to material wastage and time loss.

Another aspect that differentiates the mining and mineral industry from others is the fact that the raw material keeps changing from season to season. In the rainy season, the material will be wet and sticky and in summer it will be dry. This requires the design engineers and researchers to come up with a design that can work in both these conditions.

Discrete Element Method is a proven tool for designing and troubleshooting equipment. Mining and Mineral companies across the globe have included DEM in their development process and routinely use them for troubleshooting. In this blog,

What value will a DEM tool add?

Any simulation technology will help the user to get a deeper insight into their equipment/process. Testing at the plant scale also becomes an easy task as there will not be any material loss and downtime of the plant required.

Let’s take a very simple example of a chute. In case of a decrease in throughput of the chute, it becomes difficult to understand the underlying reason sometimes. Identifying the right area where material clogged will be really helpful in increasing the throughput. A DEM simulation can show the velocity profiles of all the particles inside the chute which help us identify the faulty region. Getting this type of insight from the real chute will be difficult as that would require us to have a chute made of transparent material which is impractical at plant scale.

What processes will I be able to design/troubleshoot?

Almost all mining-related processes can be handled using DEM. Here is a non-exhaustive list:

  • Excavation at the mining site
  • Wagon loading and unloading
  • Primary crushing
  • Stockpile
  • Conveying operations
  • Screening/sorting
  • Blast furnace
  • Fluidized beds
  • Packed beds

Is DEM capable of handling real-life material loading conditions? RockyDEM uses the power of multi-GPU processing to make plant scale simulations reasonable. Figure X shows a comparison of CPU vs GPU vs multi-GPU. Using multi-GPU will help us make these simulations way faster when compared to CPU. But that’s not it, with the new modules being introduced inside RockyDEM, the data saving time has decreased which would lead to total time-saving. Also, the advanced contact detection method helps reduce overall simulation time. We can further reduce the simulation time by using the Coarse Grain Model.

Figure x- Scalability using CPUs, GPUs and multi- GPU`s

How can I be sure that the simulation results are accurate?

All the models are implemented in Rocky are well-validated which means that we do not have to worry about the models predicting the behavior if supplied with accurate inputs. The most important input required will be material properties. To extract the material properties and correlate them to simulation parameters, calibration is required. For example, an angle of repose test which can be performed in the lab should also be performed with RockyDEM virtually and the same behavior should be replicated. Properly calibrated material properties will provide us with a highly accurate result.

I would also like to understand the effect of particle flow on my equipment, how can RockyDEM help me with that?

RockyDEM has some in-built post-processing capabilities which can be used to plot contours of stress and force on the equipment. RockyDEM is also integrated with ANSYS products like ANSYS Mechanical. So, the force maps from RockyDEM can be transferred to ANSYS Mechanical and a structural simulation can be performed to evaluate deformation, etc.., We can also perform a transient coupled analysis with ANSYS Mechanical.

We answered a few questions which any mining company might have while thinking about adopting simulations. Keep an eye on this space.

Author Name: Mr. Ishan Vyas (Application Engineer at CADFEM India)

Profile Bio: Mr. Ishan has completed his bachelor’s in Chemical Engineering with minors in Material Science. He is currently associated with CADFEM as an Application Engineer in the CFD and DEM domain. He holds an experience primarily in the areas of applications related to Chemical, pharma, oil, and gas industry involving both CFD and DEM codes. The Simulation of Chemical processes implementing DEM for New product development deeply interests him. He is an avid reader and loves Adventure sports.

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Transfer Chutes Design with Rocky DEM

This article focuses on how engineering simulations help better design transfer chutes for their smoother functioning and enhanced equipment life.

Transfer chutes are used widely for handling bulk materials. They can be used to change the direction of material flow and transfer material from one conveyor to another conveyor. A chute might seem to be a petty component in a huge plant, but it plays a significant role. If you don’t design the chute properly, you’ll witness a high maintenance cost, increased downtime and particle breakage. On the other hand, a well-built transfer chute can help reduce noise, decrease damage to conveyor belts and transfer chute walls, and reduce dust formation.

Prior to getting to design, I will list down the essential requirements for a good transfer chute design:

  1. Avoid material clogging
  2. Minimal equipment wear
  3. Minimal material degradation
DEM-Based Approach for Designing Transfer Chutes

Getting the optimum chute design is a time-consuming task because transfer chutes are not designed properly most of the times. For the above-mentioned design considerations, there are many constraints that you will need to apply while designing transfer chutes.

Discrete Element Method (DEM) can help designers such as you design better transfer chutes in lesser time. DEM can help you visualize the flow of particles (material) in transfer chute and provide useful data pertaining to each particle and all the boundaries in the chute. Needless to say, it is impossible to derive such level of detail from physical trials or finite element analysis. Besides providing much needed qualitative insights, DEM simulations enable you with the freedom to explore new designs and test them without the need for physical trials.

In the following sections, I’ll explain how Rocky DEM software will help you design high quality transfer chutes.

Avoid Material Clogging

Blockages in transfer chutes restrict the flow of material through the chute. Not only are blockages a detriment to the transport efficiency, but also they exert a lot of stress on the chute walls leading to serious damage. To make transfer chutes less prone to material blockages, impact angle should be decided based on material properties and inlet speed should also be tweaked accordingly.

Rocky DEM has all the capabilities necessary to address the needs for wet and dry material handling. Different material properties such as the rolling friction, static friction for particle interactions, elastic modulus, bulk density, adhesion coefficients can be accounted for. A unique capability of Rocky DEM is the availability of adhesion models that can replicate the flow of wet materials. This would foster the simulation of materials such as wet mortar in the construction industry or some crucial unit operations with wetting ingredients in the process industry.

Rocky DEM helps to model blockage and design better transfer chutes
Rocky DEM simulation showing blockage (blue colored particles are stationary)

Minimize Equipment Wear 

Wear leads to increased maintenance cost not only for transfer chutes, but also for the conveyor belt. Abrupt changes in material flow direction is one major reason for surface wear. The smoother the flow, the lesser will be the damage to transfer chutes. The angle at which the material hits the walls of the chute largely affects the wear. This angle will depend on the material velocity and properties of the material. Modification can be done to the chute design to minimize wear, such as by adding a curved guide surface at the mouth of the chute to direct the flow and make it smoother.

As you will understand, making these changes in physical trials and capturing test data is cumbersome. With Rocky DEM, this task is just a few clicks away. You can use any CAD tool to make geometry changes and then bring it into Rocky DEM to simulate performance of modified designs. Rocky DEM will provide you wall impact force; using this, you can decide the optimum velocity and finalize the most suitable design for the transfer chute.

Rocky DEM simulations showing Instantaneous Shear Power for transfer chutes
Instantaneous Shear Power for a transfer chute

Rocky DEM simulations showing Mean Shear Power for transfer chutes
Mean Shear Power for a transfer chute.

Minimize Material Degradation

The quality of the end product decides its price. Undesired material breakage and extravagant segregation or degradation can lead to a poor quality process outcomes. Particle degradation occurs due to impact on chute and shear either from collisions with walls or with other particles. Information about the forces that a particle experiences can give an indication of how much damage will occur.

Rocky DEM not only provides forces on each particle, but also simulates breakage of particle under higher forces using models which are backed by years of research. You can visualize the particle actually breaking into fragments as it proceeds through the chute.

Rocky DEM: Helping You Engineer Better Transfer Chutes

Designing Transfer Chutes is a complex process and testing multiple designs is an expensive affair. However, Rocky DEM makes it simpler, cost-effective, lesser equipment maintenance and upkeep, and helps you to produce a better quality product. It has the ability to

  • analyze large number of particles quickly due to its multi-GPU capabilities,
  • represent particle shapes used in your industry, and
  • multiple post-processing options to help you analyze the data efficiently.

Quite clearly, Rocky DEM will help you and your organization minimize prototype costs and product development times. You’ll recognize that these benefits will further accelerate product launches into the market and fetch your organization higher profitability margins.

Still curious to know all of this actually works? I’m going to speak in a webinar called Assessing and Improving the Bulk Material Handling Practices with Rocky DEM Simulations on February 15th at 2:30 PM IST. Come, join me in an hour of learning how Rocky DEM simulations can help you save and generate more revenue for your bulk handling business.

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