In this introductory article, we will discuss the various aspects of Particle Wear and Testing methods. During storage and transportation, materials can undergo significant wear. This wear often leads to undesired effects, such as loss of product and decreased product quality. Additionally, it can result in the formation of fines and dust, which complicates handling and processing.
At Delft Solids Solutions, our laboratory is equipped with various types of research equipment specifically designed to study the wear of solid particles. We conduct comprehensive research on both attrition and abrasion of solids. This dual approach allows us to gain valuable insights into particle wear mechanisms and their impacts on material performance.
Particle Testing Methods for Material Performance
A straightforward method for testing larger materials involves using our tablet hardness tester. This device measures the crushing strength in either the axial or radial direction of a single pellet or tablet. However, this method is not suitable for smaller particles.
To address this limitation, Delft Solids Solutions has developed a robotic compression tester. This advanced technology can measure the individual crushing strength of particles in the 100-micrometer range. By analyzing this data, we can identify the causes of undesirable material behavior and make necessary adjustments.
Improving factors such as strength, integrity, and durability is integral to product design and enhancement across nearly every industry. Our testing techniques enable manufacturers to refine their products, ultimately leading to better performance and greater customer satisfaction.
Methods for Particle Wear Testing in Bulk
The methods previously described effectively test individual particles. However, studying particles in bulk requires different approaches. For example, measuring bulk crushing strength helps assess the fines generated during stress tests at various stages of consolidation pressure.
To further analyze bulk materials, we offer a rotating drum solution specifically designed to break down granules or pellets. This method simulates attrition, allowing us to quantify the fines collected during the process. The rotating drum mimics the conditions found in industrial drum operations, providing realistic insights.
Additionally, we simulate the attrition that smaller materials may encounter during pneumatic transport. We achieve this by exposing the material to a repeated impact test. This technique is also applicable for testing fluidization attrition, which can occur when particles collide as they are fed into fluid bed installations.
By employing these methods, we provide comprehensive insights into particle wear and its implications for material performance. These techniques enable manufacturers to refine their processes and enhance product quality.
Particle Wear and Testing in Relation to Dust
As previously mentioned, the wear of particles can lead to undesirable phenomena, including loss of product quality and the formation of dust fines. Recently, Delft Solids Solutions investigated two common issues that frequently arise during powder processing.
These issues may occur during the coating process. The freshly formed coating layer can experience wear due to dynamic motion within the coating drum. This wear happens either through granule-to-granule interaction or granule-to-wall interaction. As a result, small flakes of material may chip away.
These chips can reattach to the coating layer, leading to an undesirable effect known as the “broccoli pattern,” as illustrated in Figure 1. Our research highlights the importance of understanding these phenomena to improve coating quality and reduce dust generation in powder processing.
Dust in the Wind
During the pneumatic conveying process, particle wear can escape the system and be released into the atmosphere. This release may pose a health hazard and increase the risk of explosions. In the conveying system, the most common causes of wear are particle-to-particle impacts and particle-to-wall impacts, which typically occur in the bends of the transport system.
Delft Solids Solutions has the capability to determine the level of particle breakage and dust generation after the pneumatic conveying process.
Recently, we investigated the effects of pneumatic transport on lignin granules. After the analysis cycle, we discovered that particle breakage predominantly occurs in the bend areas, driven by high airflow and resulting from both particle-to-wall erosion and particle-to-particle impact. With a relatively high air velocity of 12 m/s, approximately 10% of fines were generated during the conveying process.
This research underscores the need to address particle wear and dust formation to ensure safety and efficiency in pneumatic transport systems.
