Issues being experienced with the loading of Iron Ore Fines cargo out of Porto Sudeste, Itaguai in Brazil.
The cargo exhibits characteristics that make it prone to dynamic separation, which can compromise vessel stability. This highlights the critical importance of proper testing and careful control of moisture content.
The material contains a fines/clay fraction that slows drainage and retains moisture, which may not be evident during visual inspection or standard can testing.
While the shipper’s methods for determining the Transportable Moisture Limit (TML) appear technically sound, problems have arisen with the moisture content of the cargo at the time of shipment. Individual batches presented for loading show highly variable particle size and moisture content, with some batches exceeding the TML.
Furthermore, the shipper’s current strategy appears to focus on the weighted average moisture content of the hold or consignment, without adequately considering the safety risks posed by high-moisture batches.
The absence of effective pre-shipment measures, such as shore-based blending, to mitigate these risks. Simply placing lower-moisture material on top of high-moisture cargo does not constitute blending and does not improve the stability of the cargo below.
In fact, loading high-moisture material at the base increase’s saturation and pore water pressure, further raising the risk of dynamic separation, John Southam highlights.
Due to the lack of control over the as-loaded moisture content, the current loading approach at Porto Sudeste is considered high-risk for this type of cargo and is non-compliant with Section 4 of the IMSBC Code.
Recommendations:
- Consider appointing a local surveyor.
- Seek the opinion of a geotechnical expert.
- As well as the shipper’s declaration, members should request the particle size distribution, TML (including supporting data generated by the test) and moisture content range for all portions of the consignment presented for loading, not single or weighted average results.
- Any batches presented for shipment that have a moisture content above TML should be rejected.
- Perform regular can tests to monitor for high-risk cargo.
- Look for obvious signs of excess moisture / free water in the stockpile and in the cargo hold.
At this time, the facility appears to have limited means with which to discharge a cargo, and there is no evidence that the competent authority or competent authorities have approved by exemption (IMSBC Code Section 1.5) this approach to loading operations.