MATERIAL HANDLING

Material handling is a critical aspect of operations and logistics, focused on the movement, storage, control, and protection of goods and materials throughout the supply chain. It encompasses the methods, equipment, and systems involved in handling raw materials, parts, and finished products. Effective material handling is essential in optimizing production efficiency, reducing costs, minimizing waste, and ensuring workplace safety.

This dataset and calculations are for educational purposes only using Discrete Element Analysis (DEM).

problem definition

To analyze the behavior of particles as they are fed onto a conveyor system, specifically focusing on identifying factors that cause particles to bounce off and potentially lose material. This study aims to ensure that particles reliably stay on the conveyor during initial contact, minimizing spillage and loss.

Particle's Bulk Density

material model

The coefficient of restitution (COR) is a measure of how "bouncy" a collision is between two objects. It quantifies the ratio of relative velocity after a collision to the relative velocity before the collision.

Typical Values of Rolling Friction

Steel on steel (like train wheels on rails): μr ≈ 0.001−0.002
Rubber on concrete (like car tires on road): μr ≈ 0.01−0.015
Bicycle tire on asphalt: μr ≈ 0.002 − 0.005

The coefficient of static friction (denoted as μs) is a measure of the frictional force that must be overcome to start moving an object at rest on a surface. It represents the ratio of the maximum static frictional force (Fs) that must be overcome to initiate motion to the normal force (N) acting between the two surfaces.

The angle of repose is the steepest angle at which a pile of loose material (like sand, gravel, or grain) remains stable without sliding. It represents the balance point where gravitational forces pulling particles down are countered by frictional forces between particles, preventing slippage.

particle model

Particles model (heavy and light) based on 5 rolls feed default belt conveyor injecting 200 tonnes per hour showing the particle dispersement and the absolute rotational speed during feed and transfer.

Initial particle movement during feed.

Last particle movement after 5 seconds.

Particle distribution at 4 seconds time step.

Particle that bounces off the conveyor at approximately 50 rad/s rotational velocity.

Material interaction of the conveyor belt vs heavy material particle.

particle.gif

ANALYZING crushers

A cylindrical crusher is a type of machinery designed for reducing the size of materials by crushing, grinding, or pressing. These crushers are commonly used in mining, metallurgy, recycling, and various industrial applications to handle medium to hard materials, including minerals, rocks, and waste products.

Power consumption comparison of two rollers (1.2m in diameter) used for crushing materials running at different angular velocity.

To determine if the current cylindrical crusher design can be adjusted for producing different material sizes, several aspects of its operation and design need to be analyzed:

1. Adjustability of Crushing Gap:

Crushing Gap: The gap between the crushing elements (like the walls and/or jaws) is crucial for controlling output size.

2. Variable Speed Control:

Rotational Speed: Changing the speed of the crusher's rotating cylinder (or jaws) impacts the crushing force and the particle size of the output. Higher speeds can result in finer output, while lower speeds yield coarser material.

3. Crushing Elements (Liners):

Interchangeable Liners: Crushers often use hardened liners to handle different materials. If the crusher has interchangeable liners with varied profiles (like coarse or fine ridges), could help control the size output.

Material Hardness: Different liners may also be needed for harder materials, which might influence the final particle size due to wear resistance and crushing efficiency.

4. Feed Control Mechanism:

Even Feed Distribution: For consistent output size, the feed must be uniformly distributed. We will evaluate if the current feed mechanism can handle different materials without clogging or uneven distribution, which can affect size control.

5. Crusher Power and Capacity:

Power Requirements: Crushing finer or harder materials typically requires more power.

Capacity Constraints: Adjusting for smaller sizes may reduce throughput (as the crusher will need to apply more force or pass the material through more times).

Roller Crusher.gif

The example above demonstrates the behavior of material particles of three different sizes being randomly fed into two rollers with varying angular velocities. This setup needs to be redesigned to prevent the material from being pulverized.

A redesigned roller with different liners which influence the final particle size due to wear resistance and crushing efficiency.

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