Transportable Moisture Limit Testing, Melbourne, Victoria, Australia
Over the years ATC Williams has developed several specialised laboratory test procedures relating specifically to the ever growing mining industry and its demand for optimised, cost effective designs and increased OH&S requirements during all aspects of mining. Among these test procedures, it is the Transportable Moisture Limit testing which directly prevents the capsizing of large bulk carriers saving resources and lives.
The Transportable Moisture Limit of cargo is the maximum gross water content by weight that liquefiable solid bulk cargo may contain during transport without risk of liquefaction. The liquefaction phenomenon can see materials, most commonly iron ore fines, nickel ore and various mineral concentrates, transform from a solid dry state to following the laws of fluid dynamics.
Liquefaction can occur with the compaction of cargo under its own weight and though the vibration of both the ship’s engine and the wave motion that occurs during a voyage, with poor weather conditions or high seas sometimes aiding this process. When cargo suddenly liquefies it can greatly reduce the stability of bulk cargo ships and for decades this was one of the main causes of casualties at sea.
Transport Moisture Limit (TML) Testing
Since 1988 over 20 incidents of liquefaction of solid bulk cargoes in transit have been suspected to be the cause of bulk carriers capsizing. The resulting loss of lives and resources called for a review of the international maritime legislation concerning the export of metal ores and concentrates.
In 2011, ATC Williams was contacted by exporters of metal ores and concentrates to perform testing to determine the Flow Moisture Point (FMP) and identify the Transportable Moisture Limit (TML) of materials that the International Maritime Organization (IMO) had recently listed as Group A cargo (meaning cargo which may liquefy in transit) in the International Maritime Solid Bulk Cargoes (IMSBC) Code.
Over the last few years ATC Williams have worked towards perfecting and then further developing the Flow Table and Proctor/Fagerberg tests outlined in the IMSBC code. ATC Williams have also obtained NATA accreditation for their in-house developed test methods while testing a wide range of ores and concentrates, such as iron ore fines, bauxite, manganese, mineral sand concentrate and coal.
ATC Williams carry out routine TML testing on samples of iron ore fines for several iron ore exporters. Testing has included determination of Particle Density (SG) in accordance with AS1289 and the Proctor/Fagerberg C and D hammer procedures to determine the TML in accordance with Appendix 2 of the IMSBC Code.
Throughout this period, ATC Williams were proudly involved in the development of the Modified Proctor/Fagerberg D Hammer Test which is now the accepted method for determining the TML of iron ore fines in accordance with IMSBC Code (MSC95/3).
We have also been conducting laboratory testing programs to investigate the TML of manganese ore which is typically classified by the Particle Size Distribution (PSD), Particle Density (SG), Proctor/Fagerberg TML and the Flow Table FMP and TML tests. Samples tested include a range of material types from ‘run of mine’ to fine grade material and the use of both the Flow Table and Proctor/Fagerberg TML tests have allowed for a better understanding of the material’s behaviour under different density conditions.
In 2014 we were involved in a proficiency testing program to assist in the development of a laboratory test method for the determination of the TML of Coal. Since then The Modified Proctor/Fagerberg Method for Coal was completed and submitted to the Australian Maritime Safety Authority, with intention to be included in a future revision of the IMSBC Code.
ATC Williams have since performed TML testing for commercial coal exporters and now hold NATA accreditation for the Modified Proctor/Fagerberg Method for Coal.
The development and receipt of NATA accreditation for the new TML test methods assists our clients in safely transporting valuable mineral resources throughout the world and in so doing assists with economic growth, saving lives and protecting our marine environment from potential contamination.