Dr Michael Carr

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.

Port Waratah Coal Services has the capacity to export 140 million tonnes of thermal and coking coal annually where each ship loader transports material at a peak rate of 10,500mtph. Port Waratah are considering improvements to the life of the three Shiploader Trimmer Flap chutes as they are currently experiencing excessive wear rates, resulting in premature replacement of the Trimmer Flaps. The Trimmer Flaps are typically replaced due to the failure of the liner plate retaining bolts (welded studs) and the liner plate becoming unsecure in the Trimmer Flap shell. This is hypothesised to be related to the expansion and contraction of the liner plate due to thermally induced loads from the coal flow. This research developed a Discrete Element Model (DEM) to understand the root cause of the identified issues. An analysis has been undertaken involving field measurements and data collection utilising thermocouples, data loggers and thermal imaging cameras. It was observed the failure of the liner plate retaining studs occurred due to excessive temperature cycling as confirmed from field measurements. DEM simulations coupled with heat transfer simulations utilising accurate Shiploader geometry is also considered. Using verified material properties, a model for use in determining a design for prolonged Trimmer Flap life has been completed.

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 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.