Professor Craig Wheeler

Dust pollution related to the discharge of hoppers has drawn the attention from industries dealing with bulk solids handling. This paper presents an experimental setup to measure the dust concentration of dust suppression hoppers (DSHs) with various geometries and investigate the dust influencing factors. To understand the interactions of the bulk solids and entrained air during discharge, a coupled Computational Fluid Dynamics (CFD) and Discrete Element Method (DEM) method is developed. The behaviour of the bulk solid particles and airflow is studied numerically. Results show that DSHs with a central plug of the bulk solid suppress dust by minimising the air entrainment within the particle flow, compacting the particle flow and reducing the velocities of the particles and airflow. Moreover, hopper geometries including the hopper half angle, outlet opening and outlet diameter can have significant influences on the performance of dust suppression.

A convex pattern surface has been proposed and optimized to reduce sliding wear of bulk handling equipment by adjusting the flow behaviour of bulk material. This study aims at modelling the surface deformation of the convex pattern sample to investigate how effectively the sample reduces sliding wear. Archard wear model and a deformable geometry technique are combined to capture the sample deformation. A short-time laboratory wear experiment is performed as a benchmark to validate the numerical model. The simulation resutls indicate that there is a linear relation between the wear volume of a plain sample and the simulated revolutions, while the convex pattern sample has a quadratic trend. The wear distribution displays that the convex pattern accounts for the majority of wear of the sample. The contact behaviour demonstrates that the convex pattern facilitates the rolling of particles, resulting in the reduction of sliding distance. The numerical results indicate that the deformed convex pattern sample leads to lower overall sliding wear than a plain sample, although its effectiveness weakens as wear evolves.

The throughput of a belt conveyor system is the primary design parameter when considering a new installation, determined by the cross-section of the material on the belt, coupled with the belt speed. Optimizing this area not only improves efficiency, but also minimizes capital costs through the optimal selection of equipment. Whilst speed-related optimization has seen considerable attention, the cross-sectional area has largely been neglected due to existing design constraints of the system. Conventional belt conveyors typically utilize a 3-idler troughing configuration, which forms a trapezoidal cross-section with a parabolic surcharge. The rigidity of this support directly limits the geometry of the cross-section that may be considered. A new conveyor system developed at the University of Newcastle supports the conveyor belt by a rail-based carriage, with no relative movement between the belt and carriage. This configuration allows the cross-section of the belt to be freely optimized in order to maximize the material throughput for a given belt width, or alternatively to minimize the belt width for a given throughput. This article utilizes the calculus of variations to optimize the form of this cross section, and demonstrates that an increase in throughput of up to 30% is possible, compared to troughed installations.

A previous study revealed that a convex pattern surface can reduce sliding wear of a transfer chute. A convex pattern surface is a flat surface outfitted with a pattern of convexes defined by five parameters. A three-level definitive screening design (DSD) method combined with discrete element method (DEM) is used to investigate the influence of the five parameters and two operational conditions on the sliding wear. Two flow regimes are distinguished, namely continuous and discontinuous flow regimes, and both flow regimes can significantly reduce the sliding wear. The particle velocity and angular velocity profiles verify the guiding and rolling effect of the convex pattern on the motion of particles. A regression model fitted based on the DSD indicates that three main factors and one interaction have significant influence on the sliding wear.

The energy loss due to indentation rolling resistance in a conveyor belt system can account for up to 60% of the total power usage. It arises due to an asymmetric pressure distribution as a viscoelastic belt cover is indented by a rigid idler roll. This causes a retarding moment on the idler roll, dependent on the load, speed, idler diameter and the properties of the conveyor belt cover. As pouch conveyor systems become more prevalent in industry, the supporting structure, and thus the indentation rolling resistance of such systems is of importance. These designs typically employ curved belt profiles, or spherical idlers in order to aid belt tracking and closing. From this, a spherical indentation into a generalised Maxwell backing is modelled, and compared with experimental values. In addition to this, the strain dependency across the contact is investigated.

The indentation rolling resistance of conveyor belts is an important design consideration for long belt conveyors and can also be important for heavily loaded belt conveyors. Indentation rolling resistance is dependent on the properties of the conveyor belt, including the carcass and bottom cover as well as properties of the belt conveyor including induced loads, belt speed, ambient temperature and idler roll diameter. A purpose built laboratory test facility is described to measure the indentation rolling resistance of conveyor belts. The test facility is designed to accept both fabric and steel cord belts and test over a range of typical operating parameters and conditions. Results are presented for a range of test parameters, including; load, belt speed, idler roll diameter, ambient temperature and bottom cover compound. Application of the test data to conveyor design is also presented with the aim being to show how the test facility can be used to improve the accuracy of conveyor belt tension calculations by more accurately evaluating the performance of different rubber compounds and belt constructions.

The bulk material on a belt conveyor deforms itself due to the run through idler stations. The deformation results in energy losses which are summarised in the bulk solid flexure resistance. The right understanding of the interaction between bulk material and idler stations is important for the prediction of this resistance and the idler loads. For the calculation of the bulk material behaviour on the belt the classical analytical approach by Krause and Hettler [1] was extended by Wheeler [2] with a Finite Difference model to consider the belt deflection. DEM simulation and experimental measurements of the belt deflection were used by Ilic [3] to predict the bulk material behaviour. This paper will use coupled FEM-DEM simulations for a pure numerical analysis of the interaction between bulk material, belt and idler. In this approach a simplified FEM model for a fabric belt is combined with a calibrated DEM model for cohesionless grit The model and the results of the coupled simulation will be presented. The paper will highlight the influence of belt velocity, belt pre-tension and idler distance on the behaviour of the bulk material as well as how this approach can be used to determine the bulk solid flexure resistance. Further, the new results are compared with the findings of previous works and experimental data.

The bulk material on a belt conveyor deforms itself due to the run through idler stations. The deformation results in energy losses which are summarised in the bulk solid flexure resistance. The right understanding of the interaction between bulk material and idler stations is important for the prediction of this resistance and the idler loads. For the calculation of the bulk material behaviour on the belt the classical analytical approach by Krause and Hettler [1] was extended by Wheeler [2] with a Finite Difference model to consider the belt deflection. DEM simulation and experimental measurements of the belt deflection were used by llic [3] to predict the bulk material behaviour. This paper will use coupled FEM-DEM simulations for a pure numerical analysis of the interaction between bulk material, belt and idler. In this approach a simplified FEM model for a fabric belt is combined with a calibrated DEM model for cohesionless grit The model and the results of the coupled simulation will be presented. The paper will highlight the influence of belt velocity, belt pre-tension and idler distance on the behaviour of the bulk material as well as how this approach can be used to determine the bulk solid flexure resistance. Further, the new results are compared with the findings of previous works and experimental data.

This article discusses how determining the viscoelastic properties of the cover material of a conveyor belt, using different rheological test modes, can result in significant differences in properties for the same material and testing conditions. The viscoelastic properties are applied to two mathematical models used to predict and compare the indentation rolling resistance performance of two rubber compounds. This article demonstrates how inaccuracies in the testing of the viscoelastic properties could result in a material with higher indentation rolling resistance properties being selected for a conveying system, making the power consumption of the system larger than necessary. © 2014 Wiley Periodicals, Inc.

This article presents the outcomes from a series of physical experiments to measure the air entrainment rates encountered within a stream of freefalling particles. The experimental work presented spans a range of particle parameters and hopper geometries. From these results a new theory for the prediction of air entrainment is developed and presented. This new method was developed specifically to facilitate a better understanding in the area of fugitive dust control associated with material handling systems, which are driven by the air entrainment during freefalling. From the work presented in this article, a better prediction capability of freefalling bulk materials in either constrained, or unconstrained systems, will allow for the optimization of either passive or active dust control strategies. This article presents several distinct sections that detail the experimental work used to determine the freefall stream parameters that were conducted to allow the development of the entrainment equations. © 2013 Taylor & Francis Group, LLC.

A co-operation among Universities of Newcastle, Australia, and Magdeburg, and Germany, is established to develop and apply the new analysis methods such as Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD), for prediction of diffuse dust emission from dust exhaustion plants. The combined analysis of DEM and CFD includes two CFD simulations, the air flow in the bulk material stream and the air flow around the bulk material stream. The boundary conditions for the calculation of the air flow in the enclosure are set. The results of CFD simulations show that the exhausted air does not come from the impact zone of the material stream on the receiving belt conveyor, but from the opening above the incoming conveyor belt. It is also found that the air with the highest dust content can be found on top of the receiving conveyor.

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.

In belt conveying, indentation rolling resistance arises due to the viscoelastic contact between the conveyor belt and an idler roll. As a belt travels over an idler, an asymmetric pressure distribution is formed that opposes the direction of movement, therefore resulting in a drag force to the system. For conventional systems, this resistance can account for up to 60% of the total drive power [1]. Idler diameter is known to have a considerable influence on the indentation rolling resistance of belt conveying systems, by reducing the indentation and contact stress. But how big is too big? As handling equipment becomes more developed and readily available on-site to aid in conveying component installation, larger idler diameters are becoming a more viable option to install on long conveying systems due to their energy-saving potential. This paper presents indentation rolling resistance measurements with idler roll diameters of 152.4 mm, 219 mm, 316 mm and 400 mm to evaluate the influence of larger diameter rollers on energy savings and discusses the considerations for using them in long conveyor systems.

With recent advancements in conveying technologies, conveyors are required to achieve greater lifts, longer conveying distances and higher throughputs. As such, drive stations continue to increase in size, with gearless drive stations in excess of 10 MW in existence. A significant amount of research has been conducted into the design and optimization of these systems, however, the use of standard methodologies to quantify drive friction is a known limitation that remains. Currently, design standards use Euler's classical 'rope friction' equation to determine drive limitations, with this method failing to account for a variable friction coefficient around the drive pulley. Due to this, the calculated drive is conservative and reaches the limit of efficacy with high-capacity conveyors, due to the high belt tensions required, and the necessary overdesign in structure. This paper investigates the frictional behaviour between a belt conveyor and pulley lagging materials and presents test results demonstrating how the friction coefficient varies with changing load and slip velocity. This improved understanding of the frictional behaviour between the conveyor and drive pulley lagging will further the design capabilities of high-capacity conveyor systems.

It is common practice to analyse the flow properties of a bulk material sample for a range of Moisture Contents (MC). It can also be quite common that the material supplied requires 'drying' to analyse moisture contents at lower values than what may be supplied by the client. This paper investigates the influence of thermal drying techniques on the flow properties of bulk materials. The chosen drying techniques are Air-Drying (AD), drying at ambient temperature and Oven-Drying (OD), drying using an oven at 105 °C. The flow properties of three bulk material samples are considered with each sample compared at the same MC after the drying technique has been undertaken. Each bulk material sample also has baseline testing undertaken at the As-Supplied (AS) condition. To analyse the effects of thermal drying on bulk material flow properties, a case study is also presented to consider the anticipated changes to outlet dimensions for a funnel flow bin design.

A technique to simulate airflow around transfer chutes that involves linking Discrete Element Method (DEM) commercial package Rocky and Computational Fluid Dynamics (CFD) commercial package ANSYS Fluent is proposed. The flow of particles is first calculated in the DEM domain; after that continuum parameters of this flow (porosity, mean particle size and cell-averaged particles velocities) are calculated and used as input into ANSYS Fluent CFD package for the solution of the airflow. This solution is carried out using a single-phase moving porosity approach with User Defined Functions (UDF) for porosity and particle-based momentum terms in Fluent based on phenomenological interaction laws. The comparison against experimental results for a laboratory-scale transfer chute demonstrates a good match between experimental and computational data. Several turbulence models and particle-gas interaction laws have been tested and it was concluded that for this problem the choice of interaction laws and turbulence models does not affect the results of the simulation to any significant degree.

This paper presents an industrial case study to reduce dust emissions from a grain handling ship loader. The primary objective of the study was to reduce dust emissions to within acceptable environmental levels during ship loading. Several constraints were imposed on the solution due to time and budgetary restrictions, and the inability to add a dust suppression agent to the grain for quality reasons. A number of alternative loading chute configurations and delivery spoon profiles were examined in a pilot-scale test facility. This paper will discuss a number of alternative solutions which were investigated during the course of the study and the critical parameters of the final design. Tests showed that it was not beneficial to decelerate the product stream to keep the relative velocity of the air stream over the grain below the minimum pickup velocity. Instead, it was found that concentrating the product stream and keeping the product velocity high was more beneficial in reducing dust emissions. A reduction of 50% in dust emission was achieved through the use of specifically designed constant radius and parabolic profile loading spoons. The product stream exiting the curved spoons was found to be concentrated and stream-lined, resulting in the dust being contained within the product stream.