Dr Tiago Cousseau

Conveyor belts are extensively used for the transportation of bulk materials due to their safe operation, economy, reliability, and high capacity. The system usually consists of a long-reinforced rubber belt supported by metallic idler rolls; however, certain applications and improper maintenance see these idlers wear. Severe wear that penetrates the idler shell forms sharp edges that might cut the conveyor belt, leading to high costs and operational downtime. Consequently, polymeric idler rolls have been presented as an alternative to improve the performance of conveyor belts, averting the sharp edges of worn idler rolls and, due to their low weight, facilitating idler replacement. However, it is still necessary to assess their technical viability.

Belt conveyors offer numerous advantages for transporting granular materials over medium distances. They are known for their efficient performance, requiring minimal labor and energy input, and therefore belt conveyors are the most widely used system for bulk transportation. Understanding the causes of conveyor idler replacements is crucial since they represent the second highest maintenance cost in this transportation method, following the conveyor belt itself, which accounts for 30% to 70% of maintenance expenses. By analyzing data on the lifespan of 97,778 idler rollers provided by Vale, we have identified the primary factors leading to the replacement of impact, carrying, and return idler rollers. These causes include noise/vibration, wear, and idler seizure. Notably, noise/vibration plays a more significant role in carrying idler roller replacements (74.5%) compared to impact idler roller replacements (46.0%), which are subjected to more severe loading conditions that rapidly lead to seizure. Noise and vibration are consequences of bearing damages like pitting and spalling. In the case of return idlers, wear accounts for approximately three times more replacements than noise (62.0% and 20.6%, respectively). This discrepancy arises because these idlers do not directly bear the load of transported material; instead, abrasive wear occurs due to contact with the belt and the ore adhered to its surface. Understanding these causes of replacements enables us to gain insights into the specific operational conditions of idlers. With this knowledge, we can design more appropriate experimental plans tailored to the reality of belt conveyor idlers. This approach allows for better identification of key tests for determining idler lifespan based on their specific type.

Filtration of coal tailings and refuse has become a critical process, given a continuous push towards dry-stacking methods over conventional dam disposal. Conventionally, this process is achieved by a combination of thickening and mechanical dewatering (cyclones, filter press etc). This paper investigates the feasibility of using an open channel to passively settle coal tailings by particle size. A pilot-scale open channel was built to test coal tailings under a range of volumetric flow rates. Measurements of Particle Size Distributions (PSDs) and solids mass concentration were conducted at the open channel inlet and outlet to reflect the degree of settling. To account for the hindered settling, a modified Stokes' settling model was developed. The model was found to accurately predict observations with only a scalar multiple of Stokes' law for a single particle required, which physically reflected changes in the perceived viscosity by the settling particles. This scalar multiple was then obtained using the pilot-scale measurement data and, as it is a slurry property, this allowed for the prediction of performance under scale-up.

The automotive industry has a lack of knowledge when the subject comes to screw joint technique, especially regarding tribological interferences. These themes are not commonly explored together on studies to comprehend the behavior between contacting surfaces. When there is a specific goal, as the one proposed in this paper: to ensure all control levels to eliminate sealing deficiency risks inside combustion chamber in a low investment cost, these needs are even higher. The tribological analysis between diesel engine block and its cylinder head is essential to understand the minimum requirements to achieve the best possible sealing, mostly when it comes to assembly tightening process routines. In this sense, this work puts forward a methodology to set best tightening conditions in order to guarantee the sealing to whatever surface topography. Additionally, the acquired knowledge can be used to other similar applications associated to bolted joints, such as in other vehicle parts. Even though in other circumstances, when the critical screw joint goal focus is not on sealing efficiency, but for example on extremely high fatigue conditions exposed to external work, the method developed on this work presents a good path to achieve better clamping loads. Also, in many manufacturing processes the surface topographies may range according to the machining parameters, which are defined not considering the effects of tightening and consequently on the clamping results stability. Based on that, this study takes into account this negligence and guides to a tightening specification that increases stability on clamping load losses.