Section 8.4: Bauxite (Liquefaction Risks for Group A Bauxite)

Bauxite is the primary ore from which aluminum is extracted, making it a crucial raw material for a wide range of industries, from aerospace and construction to packaging and consumer goods. It is transported in significant quantities by sea, often on long voyages from mining regions (e.g., Australia, Guinea, Brazil, Jamaica, Indonesia) to alumina refineries worldwide. While some forms of bauxite are relatively benign, certain types of bauxite, particularly those with a high proportion of fine particles and specific moisture content, are prone to liquefaction and are classified as Group A cargoes under the IMSBC Code. The tragic loss of the bulk carrier MV Bulk Jupiter in 2015, which was carrying bauxite from Kuantan, Malaysia, and sank rapidly with the loss of 18 lives, starkly highlighted the severe liquefaction risks associated with some bauxite cargoes.

1. Characteristics and Types of Bauxite:

Composition: Bauxite is not a single mineral but a naturally occurring heterogeneous material composed primarily of one or more aluminum hydroxide minerals, typically gibbsite, böhmite, and diaspore. It also contains impurities like iron oxides (giving it a reddish-brown color, though it can also be grey, white, yellow, or pink), clay minerals, and silica.

Physical Forms:

Lumpy Bauxite: Consists of larger, coarser particles. Generally less prone to liquefaction.

Bauxite Fines: Contains a significant proportion of small particles. This is the form that poses the primary liquefaction risk. The particle size distribution and the amount of clay-like material present are critical factors.

Moisture Content: Bauxite can have a naturally high moisture content due to its porous nature and the mining/processing methods used.

Stowage Factor: Typically ranges from about 0.60 to 1.10 m³/tonne, meaning it is a relatively dense cargo, though not as dense as iron ore.

2. IMSBC Code Classification and Key Considerations for BAUXITE:

BCSN: BAUXITE

Group:

BAUXITE (Schedule for Group C): The IMSBC Code has a schedule for Bauxite as a Group C cargo. This schedule applies to bauxite that is deemed not liable to liquefy. However, the Code emphasizes that “Only bauxite cargoes meeting the following criterion are Group C: the moisture content of the cargo is less than its moisture limit for safe carriage (MLSC) which is the TML minus 10% of TML.” This statement in older versions of the code was a source of confusion. The current IMSBC code (e.g. 2022 edition, Amdt 06-21) states that bauxite may be classified as Group A or Group C. The shipper must provide a certificate for the TML and moisture content for bauxite fines if they are declared as Group A. If bauxite fines are declared as Group C, the shipper must provide a certificate stating the moisture content is less than 70% of the TML, or that the moisture content is not more than 10% and the particle size is such that there are not more than 50% of fine particles (less than 1mm).

BAUXITE FINES (Schedule for Group A): Recognizing the specific liquefaction hazard, recent amendments to the IMSBC Code have introduced a dedicated schedule for BAUXITE FINES as a Group A cargo. This schedule applies to bauxite with a significant proportion of fine particles that may liquefy.

Crucial Determination: The shipper is responsible for correctly classifying the bauxite (Group A or C) and providing the necessary documentation. However, the Master must be extremely vigilant, especially if the cargo contains a noticeable amount of fines, even if declared as Group C.

Hazards (as per IMSBC Code):

Liquefaction (Primary Concern for Bauxite Fines – Group A): This is the most severe hazard. The mechanism is similar to other Group A cargoes: compaction and vibration during the voyage can cause an increase in pore water pressure, leading to a loss of shear strength and the cargo behaving like a fluid. The Bulk Jupiter incident is a tragic testament to this risk with bauxite.

Shifting: Even if not liquefying, bauxite with a low angle of repose can shift, especially if not properly trimmed.

Dust: Some bauxite cargoes can be very dusty during loading and discharge.

High Density (Moderate): While not as dense as iron ore, it’s still a relatively heavy cargo requiring attention to tank top strength and stress distribution, especially if loaded in alternate holds or if the vessel is small.

Potential for Increased Moisture: Bauxite stockpiles exposed to heavy rainfall can absorb significant additional moisture, potentially changing a “safe” parcel into an unsafe one if not re-tested.

3. Key Hazards and Precautions Associated with Bauxite:

A. Liquefaction (Bauxite Fines – Group A):

Critical Reliance on TML/MC Certification:

For any bauxite cargo declared as Group A (Bauxite Fines), or any bauxite containing a significant proportion of fines where liquefaction is a concern, the Master must receive valid TML and MC certificates.

The certified Moisture Content (MC) must be less than the certified Transportable Moisture Limit (TML). This is non-negotiable for preventing liquefaction.

Scrutinize certificates for dates (recent testing is vital), issuing authority, and the specific test method used (the Proctor/Fagerberg test procedure is often specified for bauxite in the IMSBC Code, Appendix 2, Section 3.3, or other approved methods).

Shipper’s Declaration and Classification:

The shipper’s declaration of whether the bauxite is Group A or Group C is critical.

If declared as Group C but the cargo appears to contain a lot of fines or is visibly very wet, the Master must exercise extreme caution, query the shipper, request test certificates (TML/MC), and potentially insist on independent testing. The Bulk Jupiter report highlighted issues with how some bauxite cargoes were being classified and tested.

IMO Circulars and Industry Guidance: Following the Bulk Jupiter incident, the IMO and industry bodies (e.g., P&I Clubs, Intercargo) issued circulars and guidance emphasizing the liquefaction risks of bauxite and the need for rigorous testing and adherence to IMSBC Code provisions. Masters should be familiar with this guidance.

Visual Checks and Can Test:

During loading, observe the cargo’s appearance. Signs of excessive moisture (splattering, “slumping” in stockpiles, free water) are red flags.

The Can Test can be a useful supplementary check if concerns arise. A “fail” warrants immediate stoppage and investigation.

Cargo Not to be Loaded if Unsafe: If the MC ≥ TML, or if valid certification is not provided for a potentially liquefiable parcel, the cargo must not be loaded.

B. Cargo Shifting (Group C Bauxite or poorly trimmed Group A):

Bauxite, especially finer grades, can have a relatively low angle of repose.

Trimming: Proper trimming in accordance with IMSBC Code Section 5 is essential to minimize void spaces and reduce the risk of shifting, which could lead to a list and compromised stability.

C. Dust:

Bauxite handling can generate significant amounts of fine reddish-brown or grey dust.

Health Hazard: Inhalation of bauxite dust can cause respiratory irritation. Long-term exposure may lead to more serious lung conditions. Appropriate PPE (dust masks/respirators, goggles) is essential for crew and stevedores.

Environmental and Nuisance Issues: Dust can cause local air pollution and contaminate decks, superstructures, and surrounding areas.

Dust Control: Similar measures as for other dusty cargoes (closed non-working hatches, accommodation protection, terminal dust suppression, deck washing).

D. Abrasiveness and Potential for Hold Damage:

Bauxite can be quite abrasive. Careless grab operation during discharge can damage tank tops, hopper plates, and hold coatings.

4. Pre-Loading Preparations:

Hold Cleanliness: Typically, a “normal clean” or “sweep clean” is acceptable after similar non-contaminating cargoes. However, always confirm specific requirements with the shipper/charterer. Holds must be dry.

Bilge Wells: Clean, strum boxes clear and protected from ingress of fines (e.g., with burlap). Suctions tested.

IMSBC Code and Shipper’s Declaration:

Obtain and meticulously review the shipper’s declaration and all accompanying certificates (TML, MC, any other required tests). Pay extremely close attention to the declared Group (A or C) and the moisture parameters if Group A is declared or suspected.

Consult the relevant IMSBC Code schedule(s) for BAUXITE and BAUXITE FINES.

Stability and Stress Calculations: Prepare a detailed stowage plan and loading sequence using the loading computer, considering bauxite’s density, ensuring tank top strength is not exceeded, and that longitudinal stresses and stability remain within limits at all stages. Alternate hold loading may be considered for stress management on some vessels.

Awareness of Recent Industry Alerts: Ensure the bridge team is aware of any recent IMO circulars, P&I Club advisories, or industry guidance specifically related to the safe carriage of bauxite.

5. Loading Operations:

Strict Adherence to Sequence and Stress/Stability Monitoring: As with all dense cargoes.

Continuous Monitoring for Liquefaction Indicators (if loading Group A or suspect fines):

Visual checks of cargo appearance on conveyor and in hold.

Perform Can Tests if any doubt.

Be prepared to STOP LOADING IMMEDIATELY if liquefaction is suspected. This is a critical safety intervention.

Trimming: Ensure cargo is trimmed as per IMSBC Code requirements to minimize shifting risks.

Dust Control: Implement appropriate measures.

Weather: Avoid loading bauxite fines during periods of heavy rainfall, as this can significantly increase the moisture content of exposed cargo. If rain occurs, stockpiles that have been tested may no longer be representative.

6. Precautions During Voyage:

Cargo Shift: Monitor for any signs of cargo shifting, especially in heavy weather.

Liquefaction Monitoring (for Group A cargoes): While liquefaction usually initiates due to compaction and vibration, any signs of instability, unexplained list, or unusual cargo movement during the voyage must be treated with extreme seriousness. Options are very limited if widespread liquefaction occurs at sea.

Ventilation: The IMSBC Code schedule for BAUXITE (Group C) states “No special requirements.” For BAUXITE FINES (Group A), it typically states “No special requirements” regarding ventilation for the cargo itself (as ventilation does not prevent liquefaction). However, if excessive dust was generated during loading, some surface ventilation might be considered to clear the ullage space before sealing for sea, provided it doesn’t introduce moisture. Always prioritize keeping the cargo dry.

7. Discharge Operations:

Dust Control: Manage dust generation.

Grab Damage: Supervise grab operations to minimize damage to hold structures.

Complete Discharge: Ensure holds are discharged as thoroughly as possible. Bauxite residues can be sticky and hard to remove.

8. Master’s Key Responsibilities Specific to Bauxite:

Extreme Vigilance on Liquefaction Risk for Fines: This is the overriding safety concern. The Master must be absolutely satisfied with the TML/MC certification and the cargo’s condition before and during loading. Do not be pressured to load if there are valid safety concerns.

Challenge Incorrect Classification: If a cargo appearing to be bauxite fines is declared as Group C without adequate supporting evidence (e.g., proper TML/MC certification showing it’s safe, or robust particle size analysis as per recent Code amendments), the Master must challenge this and insist on full compliance with Group A requirements if liquefaction is a possibility.

Adherence to Stress Limits: Manage loading to keep SF and BM within permissible limits.

Consultation: If in any doubt about the safety of a bauxite cargo, especially fines, consult the company (DPA), P&I Club, and consider appointing an independent expert surveyor.

Knowledge of Latest Guidance: Stay informed about the latest IMO circulars and industry best practices regarding bauxite carriage, as this area has received significant attention following incidents.

The carriage of bauxite demands heightened awareness and extreme caution from the Master, especially when the cargo contains fines. The potential for liquefaction is a life-threatening hazard that can only be mitigated by rigorous adherence to IMSBC Code testing and certification requirements, vigilant monitoring during loading, and a willingness to stop operations if safety is compromised. The lessons from past incidents must inform every bauxite loading operation.