COVER STORY
Industry outlook: current landscape fosters research and development Experts from TUNRA Bulk Solids look at some of the current bulk handling tech trends and how new testing and simulation techniques are required to keep up in an evolving landscape.
Examples of “red mud” (bauxite tailings) received for flow properties testing at TUNRA Bulk Solids.
THE DEPLETION OF HIGH-GRADE mines, combined with advancement in mineral processing technologies, has transformed sub-economic minerals into valuable ores. Tailings valorisation, alongside the decrease in popularity of dams as storage facilities after major accidents of Mariana in 2015 and Brumadinho in 2019 has also led to changes. Now, there is a significant increase in the need for storage and handling of “dry” tailings, and the consequent need for flow properties testing and characterisation of materials that were previously less frequent. Tailings, lower-grade, and below water table ores all have something in common: they are typically difficult to handle and can be very challenging to test with traditional testing technologies. Direct shear tester and design charts have come a long way since Andrew Jenike’s pioneering work in the mid-1960s on storage and flow of bulk solids, and they still form the basis for the design of materials handling facilities. However, these methods have limitations and may not produce useful results in the case of very plastic
materials. Furthermore, the trend towards sustainable mining and energy sources requires handling materials with previously unseen characteristics, such as the rapid increase in global demand for rare-earth metals. This increase in demand brings many challenges that include the need for new methods of materials handling assessment.
Increased focus on sustainability generates the need for improved design: There is a continued focus on environmental and health concerns related to dust emissions in the energy and resources industry. In Australia, the Work Health and Safety Act and Regulations set out the limits of exposure both in terms of a Time Weighted Average (TWA) and ShortTerm Exposure Limit (STEL), which must be observed. Dust remains a key challenge in designing and operating specific links in the materials handling chain including transfer chutes and train loading, as well as in the holistic management of rail and port operations. With the short supply of
18 І Australian Bulk Handling Review: November/December 2021
water continuing to be a key challenge, active dust suppression is being replaced wherever possible by passive dust control through effective design. This has propelled the use of characterisation techniques such as the determination of the Dust Extinction Moisture for materials beyond coal, even though the dustiness test (Australian Standard AS 4156.6-2000) was originally developed for Australian coal. The combined use of laboratory characterisation including the dustiness and wind tunnel testing, and computational simulations like Computational Fluid Dynamics (CFD) to assess dust propagation and scale modelling, have become a design requirement for many operations, with some major players conducting regular tests several times a year.
Plant efficiency requirements drive advanced monitoring and simulation techniques: Higher throughputs are needed to meet demand while keeping changes to existing plant to a minimum. This results in an increased number
