Alumina: IMSBC Code Schedule and Carriage

Alumina is aluminum oxide, Al2O3, and it is carried in bulk under the Bulk Cargo Shipping Name ALUMINA as a Group C solid bulk cargo under the IMSBC Code , adopted by IMO resolution MSC.268(85) on 4 December 2008. The schedule gives a bulk density of 781 to 1,087 kg/m3 and a stowage factor of 0.92 to 1.28 m3/t. One sentence in the HAZARD field governs the whole carriage: “Alumina dust is very abrasive and penetrating. Irritating to eyes and mucous membranes.” It is not bauxite , it does not liquefy, and it carries no chemical hazard, no IMDG class and no UN number.

What alumina is and how it is offered for carriage

Alumina is the refined oxide that sits between bauxite ore and aluminum metal, and the grade that fills most bulk carriers is smelter-grade alumina, a feedstock rather than a finished product. Refineries produce it from bauxite by the Bayer process , then ship it to smelters where it is reduced to aluminum in electrolytic cells. The ALUMINA schedule describes it as a fine, white odourless powder with little or no moisture, insoluble in organic liquids, at a moisture content of 0 to 5 percent, and adds the sentence that decides most operational arguments about the cargo: if wet, alumina is unpumpable.

Almost everything that makes alumina demanding comes down to particle size and abrasion rather than chemistry. It does not burn, does not react with the steel of a clean dry hold, and emits no gas during the voyage.

Smelter-grade alumina and why it is deliberately under-calcined

Smelter-grade alumina is produced by calcining aluminum hydroxide to drive off the chemically bound water and convert the hydroxide to oxide, and the firing is stopped short on purpose. The gibbsite sequence runs through the gamma, delta and theta transition phases at roughly 800 to 1,000 degrees Celsius, with irreversible conversion to alpha alumina, corundum, above about 1,100 degrees Celsius. Smelter-grade material is held in the transition range so that it retains a surface area near 60 to 85 m2/g.

That surface area is the point. The smelter uses alumina as the adsorbent in its dry scrubber, capturing hydrogen fluoride from the cell fume before the same alumina is fed to the cells. Fully alpha calcined aluminas, the ceramic and abrasive grades, are fired at roughly 1,200 to 1,300 degrees Celsius and have lost that porosity. The shipping consequence follows directly: the cargo is porous, so it adsorbs water from humid air, which is treated below under cargo condition.

The Bayer process and the origin of the fines

Bauxite is digested in hot caustic soda, which dissolves the aluminum content as sodium aluminate while most other minerals stay solid and are removed as red mud. The clarified liquor is cooled and seeded so aluminum hydroxide precipitates, and that hydroxide is then calcined. Precipitation and calcination together control the particle size distribution.

Attrition during calcination, conveying and ship loading generates the fine fraction that becomes airborne, and it is that fraction, not a contaminant, which produces the schedule’s abrasive dust hazard. The dust is the cargo itself, ground finer by handling. A real smelter-grade specification limits the fraction below 45 micrometres to 15 percent or less, and for the health-relevant cut the standard is ISO 7708:1995, which defines the inhalable, thoracic and respirable conventions, the respirable convention having a 50 percent cut at 4 micrometres.

Chemical-grade and specialty aluminas

Outside the smelter feed stream sits a family of higher-value aluminas used in refractories, abrasives, ceramics, polishing compounds, catalyst supports and water treatment. These move in smaller parcels, often in containers or bags rather than open bulk, and several carry their own IMSBC entries with different physical data. BROWN FUSED ALUMINA is the clearest case: a dense abrasive product carried as a Group C cargo at 1,650 to 2,000 kg/m3, far heavier and tighter-stowing than the smelter-grade powder.

The IMSBC schedule for alumina

The individual schedule is the operative document, and for ALUMINA it is short because the cargo is benign in every respect except dust. The IMSBC Code became mandatory under SOLAS Chapter VI on 1 January 2011, and the mechanism is worth naming precisely: MSC.268(85) adopted the Code, but it was resolution MSC.269(85), adopted the same day, whose Annex 2 amended SOLAS chapters VI and VII to give it force. SOLAS regulation VI/1-2 carries the obligation in a single sentence: the carriage of solid bulk cargoes other than grain shall be in compliance with the relevant provisions of the IMSBC Code.

Every figure below is from the schedule as amended by resolution MSC.539(107), amendment 07-23, adopted 8 June 2023 and mandatory since 1 January 2025.

Group, class, UN number and MHB status

ALUMINA is Group C, and under the current definition that classification is purely residual. Amendment 06-21, resolution MSC.500(105), rewrote section 1.7 so that Group C consists of cargoes classified as neither group A nor group B. The older formulation, cargoes neither liable to liquefy nor possessing chemical hazards, no longer appears in the Code.

The schedule records Class, Subsidiary hazard(s) and MHB all as Not applicable, and a Group C schedule carries no UN number row at all. Because alumina is not dangerous goods in solid form in bulk, SOLAS Chapter VII part A-1 does not engage at any point.

One inference to avoid: the absence of a UN number is not what makes alumina non-MHB. Section 1.7 defines materials hazardous only in bulk as materials which may possess chemical hazards when carried in bulk other than materials classified as dangerous goods in the IMDG Code, so MHB status is independent of a UN number. ALUMINA HYDRATE proves it inside this same family, carrying no UN number and MHB code CR for corrosive solids. Alumina is not MHB because its schedule says so.

Bulk density, stowage factor and the angle of repose

The schedule gives a bulk density of 781 to 1,087 kg/m3 and a stowage factor of 0.92 to 1.28 m3/t, and neither figure is mandatory. Section 1.4.2 lists the Characteristics text of an individual schedule, other than the Hazard classification block, as recommendatory or informative, and section 1.2.1 states that the schedule properties are given only for guidance and that current valid information must be obtained from the shipper before loading. The Group, Class, Subsidiary hazard(s) and MHB cells are the mandatory part. The density and stowage-factor cells are not.

That distinction has a practical edge. The schedule range spans 39 percent, while a real smelter-grade parcel sits in a much narrower band near 930 to 1,000 kg/m3, so planning on the schedule midpoint rather than the declared figure is the characteristic alumina loading error.

The angle of repose reads Not applicable, and the reason is the opposite of the one usually given. Alumina is a cohesive cargo under the Code. Appendix 3 paragraph 1.1 lists the cargoes that are non-cohesive when dry, ALUMINA is absent from that list, and paragraph 1.3 provides that all cargoes other than those listed are cohesive and should be treated as cohesive until otherwise shown. Section 5.3.2 then states that the angle of repose is not an indicator of the stability of a cohesive bulk cargo and is not included in the individual schedules for cohesive cargoes. A source quoting alumina at 35 to 40 degrees is not reading the in-force schedule, and the quantitative trimming ladder that depends on the angle of repose does not reach this cargo.

Size, moisture and the hazard field

Size is recorded as fine powder and moisture content as 0 to 5 percent, the latter in the DESCRIPTION field rather than as a characteristics row. The HAZARD field runs to three sentences, and the third is often dropped in secondary sources: “Alumina dust is very abrasive and penetrating. Irritating to eyes and mucous membranes. This cargo is non-combustible or has a low fire-risk.”

Abrasive dust wears at moving parts, packs into bearings and seals, and works into accommodation and machinery spaces through any gap. Penetrating dust migrates rather than settling. Those two adjectives are why a Group C entry still carries weather precautions, bilge protection and personnel-protection wording that an inert cargo would not need.

The fields that read No special requirements

Five fields of the ALUMINA schedule read No special requirements, and each one is an answer a mate needs: STOWAGE AND SEGREGATION, HOLD CLEANLINESS, VENTILATION, CARRIAGE and DISCHARGE. Reading them as blanks rather than as answers is a mistake.

HOLD CLEANLINESS is the consequential one. The Code imposes no cleanliness standard on alumina at all, so every cleanliness argument on an alumina fixture is a contractual argument and not a regulatory one. VENTILATION and CARRIAGE mean no gas monitoring, no temperature monitoring and no surface inspection regime, which is the operative contrast with coal and direct reduced iron . DISCHARGE means that everything the trade does at the discharge berth is practice rather than obligation.

There is also no EMERGENCY PROCEDURES block, which is a clean and checkable Group C marker: that block appears only on Group B entries, and ALUMINA HYDRATE carries one because it is Group A and B.

Amendment history and what governs a fixture today

Amendment 07-23 is mandatory and amendment 08-25 is adopted but not yet in force. The Code is amended on a two-year cycle , with each set entering into force on 1 January of an odd-numbered year, and the current chain is:

Two features of that table are easy to get wrong. Amendment 06-21 is the only set whose entry into force is not 1 January, having been adopted on 28 April 2022 and entered into force on 1 December 2023, after which the next interval compressed to thirteen months to recover the rhythm. And the two-digit suffix is the drafting-cycle year rather than always the adoption year, which is why 06-21 carries a 21 despite a 2022 adoption.

Amendment 07-23 added BROWN FUSED ALUMINA to the Code as a new schedule, and it added bulk density to the shipper’s declaration list at 4.2.2.7, tied to SOLAS regulation XII/10 . Amendment 08-25, resolution MSC.575(110) adopted on 26 June 2025, may be applied on a voluntary basis since 1 January 2026 under operative paragraph 4 of that resolution, and becomes mandatory on 1 January 2027. The Code carries no voyage-straddling rule, so a ship trading across the turn of 2026 into 2027 loads to the set in force on the day of loading.

Alumina variants in the Code, and the declaration trap

The word “calcined” means different things in the trade and in the Code, and mixing them up sends the ship to the wrong schedule. Getting the Bulk Cargo Shipping Name right on the declaration is the first thing to check on an alumina fixture, because the entries differ in group, in hazard and in every physical particular.

ALUMINA, CALCINED is calcined clay

ALUMINA, CALCINED in the IMSBC Code is not smelter-grade alumina. The schedule describes a light to dark grey cargo consisting of small particles and lumps, with no moisture content, at a single bulk density of 1,639 kg/m3 and a stowage factor of 0.61 m3/t, and it records the hazard as no special hazards. The Appendix 4 index settles the identification by cross-referencing the entry from “Calcined clay”.

Smelter-grade alumina is calcined in the metallurgical sense, since it has been fired to drive off the bound water, but it is white fine powder at 0 to 5 percent moisture and 781 to 1,087 kg/m3. It is declared under ALUMINA. There is no choice to be made between the two entries on grounds of grade or documentation.

ALUMINA HYDRATE is Group A and B

ALUMINA HYDRATE is the entry that breaks the pattern, and it is the one that carries real risk. It is classified Group A and B, carries MHB hazard code CR for corrosive solids, has a bulk density of 500 to 1,500 kg/m3 and a stowage factor of 0.67 to 2.00 m3/t, and is liable to liquefy if shipped at a moisture content in excess of its transportable moisture limit. Its hazard field adds skin to the irritation list that ALUMINA does not carry, and its stowage and segregation field requires it to be separated from oxidizing materials.

Hydrate is the intermediate that has not yet been calcined to oxide, and the Appendix 4 index lists “Aluminium hydroxide” as its secondary name. A cargo declared as alumina hydrate triggers the moisture content and TML certification of a Group A cargo under IMSBC 4.2.2.10, along with the transportable-moisture-limit regime in sections 7 and 8. None of that reaches ALUMINA.

ALUMINA SILICA and BROWN FUSED ALUMINA

ALUMINA SILICA is a Group C cargo at 1,429 kg/m3 and a stowage factor of 0.70 m3/t, described as white and consisting of alumina and silica crystals with a low moisture content of 1 to 5 percent, 60 percent lumps and 40 percent coarse grained powder, with the size field recorded as Not applicable. The pelletised form, ALUMINA SILICA pellets, sits at 1,190 to 1,282 kg/m3 and 0.78 to 0.84 m3/t, with pellets of 6.4 to 25.4 mm in length and 6.4 mm in diameter.

BROWN FUSED ALUMINA was added by amendment 07-23 and is the densest of the family at 1,650 to 2,000 kg/m3 and 0.50 to 0.61 m3/t, with a size up to 30 mm. Two of its provisions have no counterpart in the ALUMINA schedule. An application clause limits the schedule to cargoes containing less than 10 percent of fine particles below 1 mm. And its LOADING field warns that when the stowage factor is equal to or less than 0.56 m3/t the tank top may be overstressed unless the cargo is evenly spread across the tank top, which is the Code’s threshold for a high-density cargo. Its weather precautions read No special requirements, unlike every other alumina entry.

Shipper declaration, documentation and the right to refuse

The shipper must declare an alumina cargo in writing before loading, and the group classification removes part of that duty but not the duty itself. SOLAS regulation VI/2 places the obligation on the shipper to provide the master with appropriate information on the cargo sufficiently in advance of loading, and routes the content to section 4 of the Code. The group declaration itself is required by IMSBC 4.2.2.2, not by SOLAS, which is a distinction worth keeping straight when a dispute turns on which instrument was breached.

Section 4.2.2 now carries eighteen items, up from sixteen in the 2008 text. For a Group C alumina cargo the live ones are the Bulk Cargo Shipping Name at 4.2.2.1, the group declared as C at 4.2.2.2, the total quantity at 4.2.2.5, the stowage factor at 4.2.2.6, the bulk density at 4.2.2.7 where SOLAS XII/10 applies, the trimming need and procedures at 4.2.2.8, the harmful to the marine environment status under MARPOL Annex V appendix I at 4.2.2.17, and national requirements at 4.2.2.18. The information must be accompanied by a declaration under 4.2.3.

What Group C removes is the moisture regime. IMSBC 4.2.2.10 limits the moisture content and TML certificate to the case of a group A cargo, so no TML certificate, no moisture declaration, and none of the sampling intervals in section 4.5. The wording narrowed over time, since the 2008 text framed the trigger as a concentrate or other cargo which may liquefy, so an older source may describe the exemption differently.

Where the master’s authority actually comes from

Section 4 of the Code confers no power to refuse a cargo , which is worth stating because the power is often attributed to it. What the instruments give is narrower and more specific. IMSBC 5.1.3 gives the master the right to require that the cargo be trimmed level where there is any concern regarding stability. SOLAS regulation VI/7.5 gives the right to suspend cargo operations where the ship’s structural limits are exceeded or are likely to be, with a duty to notify the port State. SOLAS VI/6 requires the master to hold comprehensive stability and cargo distribution information before loading begins.

Beyond those, the general refusal right rests on SOLAS VI/1-2 read with the master’s overriding authority under paragraph 5.2 of the ISM Code , and on the terms of the voyage charter party or time charter party . On an alumina fixture the practical refusal grounds are documentary, meaning no declaration or no density, or physical, meaning visibly wet cargo or holds not to the contractual standard. They are not liquefaction grounds.

Hold preparation and the cleanliness standard for alumina

Holds for alumina must be clean, dry and tight, and the standard they are measured against comes from the charter party rather than from the Code. Alumina is discharged straight into a smelter feed system, so contamination from a previous cargo, rust scale or residual moisture is a quality failure as well as a stowage one. The general standards behind this sit in the cargo hold preparation standards article.

The cleanliness grade is contractual, not regulatory

Because the schedule’s HOLD CLEANLINESS field reads No special requirements, the specification in the fixture is the whole of the obligation. Skuld sets out five standards in descending order: stringent clean, grain clean, normal clean, shovel clean and load on top. Skuld describes stringent clean, also called hospital clean , as the highest of them, requiring 100 percent intact paint coatings on all surfaces including the tank top, all ladder rungs and the undersides of hatches, and notes that such standards will only be met by vessels trading exclusively in such cargoes.

Grain clean is what Skuld records as the most common requirement: holds clean, swept and washed down with fresh water, free from insects, odor, residue of previous cargo, lashing material, loose rust scale and paint flakes, then dried, well ventilated and ready to receive the intended cargo subject to inspection. On alumina the grade tracks the tonnage. A conventional bulker on a spot fixture is typically held to grain clean as the floor; dedicated tonnage, and any fixture where the receiver’s feed system is contamination critical, is held to stringent clean.

The reason the grade matters is a specification rather than an aesthetic. Receiver limits for smelter-grade alumina run to hundredths of a percent for silica, iron oxide, titania and lime, against a residual soda content of roughly 0.3 to 0.4 percent Na2O that is a Bayer process artefact rather than a contaminant. Against limits that tight, rust scale or paint flake fails the specification long before anyone sees a stain.

The cleanliness specification belongs in the fixture rather than in a phone call at the load port. Skuld records a case in which a vessel had not been able to carry out the planned cleaning during the sea voyage because of heavy weather, lacked sufficient cleaning stores on board, and could not source materials locally, which led to a defence dispute between owners and charterers over who carried the delay and the cost.

Bilge wells, strainer plates and the covering method

The most cargo-specific preparation is sealing the bilge wells so that fine powder cannot sift into the bilge system. The schedule’s PRECAUTIONS field requires that bilge wells shall be clean, dry and covered as appropriate to prevent ingress of the cargo, and IMSBC 2.2.2 requires that due consideration be given to bilge wells and strainer plates, for which special preparation is necessary, to facilitate drainage and to prevent entry of the cargoes into the bilge system.

The Code prescribes the outcome and never the material. The trade method is one or two layers of clean burlap or hessian over the strainer plates, secured with cement wash or tape so the wrapped plates sit flush with the tank top and cannot be dislodged by a bulldozer during trimming or discharge. IMSBC 2.2.3 adds that bilge lines, sounding pipes and other service lines in the cargo space must be in good order. Note the contrast with ALUMINA HYDRATE, whose schedule additionally requires the bilge system to be tested before loading to confirm it is working. ALUMINA carries no such test. Related systems detail sits in the marine bilge and ballast systems article.

Hatch covers and weathertightness

Because alumina must be kept dry, hatch cover weathertightness is verified before loading rather than assumed. The standard non-destructive checks are the chalk test on the compression bars and the hose test or ultrasonic test on the seals and cross-joints, covered in the marine hatch covers and weathertight closures article. A leak that is a minor nuisance under a coarse ore is a direct cargo-damage and dust-escape path under a fine powder, and the discipline that keeps rain out also keeps abrasive dust in.

Loading and trimming

Alumina loads through shiploaders and largely fills the hold on its own, so the loading discipline is about weather, distribution and dust rather than about levelling. The cargo is highly flowable as it pours and needs no special trimming beyond the general provisions.

What the trimming requirement actually says

The LOADING field reads: “Trim in accordance with the relevant provisions required under sections 4 and 5 of this Code.” That sentence is the Code’s default LOADING entry and appears on 211 schedules in the 07-23 text, so it says nothing specific about alumina.

Section 4 contributes exactly one item to trimming, the shipper’s duty at 4.2.2.8 to declare the need for trimming and the trimming procedures as necessary. Section 5 carries the substance, and it is graduated. Section 5.1.1 gives the purpose: trimming a cargo reduces the likelihood of the cargo shifting and minimizes the air entering the cargo. Section 5.1.2 requires holds to be as full as practicable without excessive loading on the bottom structure, and the cargo to be spread as widely as practicable to the boundary of the cargo space, subject to any alternate hold loading restriction under SOLAS Chapter XII . Because alumina is cohesive, section 5.3 routes it to those general provisions and the quantitative unevenness limits in section 5.4 never engage.

Hatch closure is not the Code’s rationale for trimming, and the levelling requirement is not there to let the covers land.

Weather suspension and the non-working hatch rule

The WEATHER PRECAUTIONS field is short and absolute, and it carries three sentences rather than the two usually quoted: “This cargo shall be kept as dry as practicable. This cargo shall not be handled during precipitation. During handling of this cargo all non-working hatches of the cargo spaces into which this cargo is loaded or to be loaded shall be closed.”

The third sentence is the one that gets missed. Hatches come across between pours, not only at the end of loading, and the requirement covers holds that are still to be loaded as well as those in work. Loading stops in rain, which is why alumina terminals favour covered conveyor galleries and enclosed loaders. Wet alumina is heavier, stickier, harder to discharge cleanly and more corrosive to the hold, so waiting out a squall is cheaper than the consequences of loading through it. Unlike ALUMINA HYDRATE, whose weather precautions permit handling during precipitation under specified procedures, ALUMINA has no such carve-out.

The loading plan and the terminal interface

The loading plan for a bulk carrier is governed by SOLAS regulation VI/7, which requires the loading booklet and an agreed loading or unloading plan lodged with the port State, and by the BLU Code , resolution A.862(20), adopted on 27 November 1997. In the European Union the BLU Code takes legal force through Directive 2001/96/EC of 4 December 2001, which establishes harmonised requirements and procedures for the safe loading and unloading of bulk carriers and applies to all bulk carriers regardless of flag calling at Member State terminals. That directive gives force to the BLU Code rather than to the IMSBC Code, which it does not reference.

The ship and shore responsibilities across that interface are set out in the stevedoring and cargo handling operations article, and the notice of readiness and statement of facts govern when the clock starts and what is recorded against it.

Stowage, tank top loading and stability

Alumina is deadweight limited rather than volume limited, but it is not the very stiff, low centre of gravity cargo that iron ore produces. At a stowage factor near 1.0 m3/t the cargo occupies roughly three quarters of a geared bulk carrier’s grain capacity, so the ship reaches her marks with the holds well short of full and the cargo surface sitting high rather than low. In cube per tonne alumina sits between iron ore and coal and closer to a heavy coal.

The stability consequence follows from that. The metacentric height on a full alumina cargo is moderate rather than large, so the roll period is not the short, sharp one that a dense ore cargo gives, and the loading plan aims at a comfortable metacentric height within the margins the intact stability criteria allow. There is no liquefaction or shifting concern: the Not applicable angle of repose reflects a cohesive powder that does not form an avalanching slope, and once trimmed reasonably level and the holds closed the cargo needs no monitoring beyond routine. That is the sharp contrast with bauxite, which has both a coarse Group C form and a fines form liable to cargo liquefaction and dynamic separation .

Tank top loading and the high-density threshold

The binding structural constraint on a dense cargo is the permissible tank top load and the hull girder limits as the load is distributed between holds, not the grain capacity. The Code’s own threshold for a high-density solid bulk cargo is a stowage factor of 0.56 m3/t or less, which is the figure that appears in the BROWN FUSED ALUMINA loading clause. ALUMINA at 0.92 to 1.28 m3/t is nowhere near that threshold, so the tank top overstress warning that attaches to brown fused alumina does not attach to it.

The load the tank top actually sees is the product of the cargo bulk density and the stow height:

The pour sequence and the resulting bending moment and shear are governed by the ship’s approved loading manual and its loading instrument, covered in the marine stability booklet and loading computer article, with the underlying structural response in hull strength and longitudinal bending . The bulk carrier article covers the structural design that sets those limits, and bulk carrier size classes covers the fleet segments that carry the cargo.

Converting between density and stowage factor

Bulk density and stowage factor describe the same physical fact from opposite directions and are reciprocals once the units are reconciled, which is why the schedule quotes both. Section 12 of the Code carries the conversion tables.

Here \(SF\) is the stowage factor in cubic metres per tonne, \(\rho_b\) is the bulk density in kilograms per cubic metre, and the constant 1,000 converts kilograms to tonnes. The schedule’s own endpoints check out against it: 781 kg/m3 gives 1.28 m3/t and 1,087 kg/m3 gives 0.92 m3/t. The mass a given hold volume will take follows directly:

The density that matters is the as-loaded bulk density including void space, not the solid density of the material. For reference the solid density figure of about 3,950 kg/m3 that circulates for alumina is the density of alpha alumina, corundum, quoted at 3.95 to 3.99 g/cm3. Smelter-grade alumina is not pure alpha, transition aluminas sit nearer 3.6 g/cm3, and the particles are porous, so its true particle density is below that figure and its bulk density is lower again by the void fraction.

Both the density and the stowage factor for a specific parcel come from the shipper’s declaration rather than from the schedule range, and both can be checked against the in-force schedule data using the IMSBC cargo finder on ShipCalculators.com .

Dust, personnel and machinery protection

The dust is the working hazard of alumina and it acts on three fronts: people, machinery, and the cargo’s escape from the hold. The schedule’s requirements are specific and they are the mandatory part of the entry.

Personnel exposure and protective equipment

Alumina dust irritates the eyes and the mucous membranes of the nose, throat and airways, and the fine fraction is respirable. The PRECAUTIONS field requires that persons who may be exposed to the dust wear goggles or other equivalent dust eye-protection and dust filter masks, with protective clothing as necessary.

IMSBC 3.3, health hazards due to dust, adds a wider regime that the schedule alone does not convey: a high standard of personal hygiene, protective skin creams, personal washing and the laundering of outer clothing. Crew involvement in alumina loading is usually limited because terminals run enclosed systems, but hold entry for inspection, sweeping or maintenance still demands the full set. Occupational exposure limits are worth treating carefully, because there is no alumina-specific international limit and the values commonly quoted are for aluminium metal and insoluble compounds as Al, or are national particulate limits, rather than limits for alumina as such.

Machinery, accommodation and equipment

The schedule requires that appropriate precautions be taken to protect machinery and accommodation spaces from the dust of the cargo, and separately that due consideration be paid to protect equipment from it. That second limb reaches deck machinery, cranes and external navigational aids, and it is the one most often left out.

IMSBC 2.2.5 requires ventilation systems to be shut down or screened and air conditioning to be placed on recirculation during loading or discharge, so that dust does not reach living quarters. IMSBC 2.2.6 requires dust contact with the moving parts of deck machinery and external navigational aids to be minimised, and 3.5.5 requires ventilation to be arranged so that escaping dust cannot enter accommodation or interior spaces. Abrasive dust reaching a bearing, a seal, an air intake or a ventilation fan accelerates wear and fouls filters, so the cargo that escapes the hold is the cargo that damages the ship. Coating and steelwork protection is covered in marine cathodic protection and hull coatings .

Enclosed space entry after a benign cargo

A Group C cargo does not make a hold a safe space, and alumina is the cleanest illustration of that rule. Alumina depletes no oxygen and emits no gas, but IMSBC 3.2.2 is unconditional: cargo spaces and adjacent spaces may be depleted in oxygen or may contain toxic or asphyxiating gases, and an empty cargo space or tank which has remained closed for some time may have insufficient oxygen to support life. Rust of the steel structure consumes oxygen in a closed hold whatever is in it.

Section 3.2.4 requires entry procedures taking account of the IMO recommendations, and the ship-side requirements are SOLAS III/19 drills and the portable atmosphere testing instruments required by SOLAS XI-1/7 on ships of 500 GT and above since 1 July 2016. Procedure detail sits in enclosed space entry and marine confined space entry and tank inspection .

Ventilation, water ingress and cargo condition

Alumina requires no ventilation and no carriage monitoring, and its condition changes anyway. Both the VENTILATION and CARRIAGE fields read No special requirements, so there is no ventilation schedule to run and no hold atmosphere or temperature regime to record.

What does change is moisture. Smelter-grade alumina is porous by design, and the porosity that makes it work as a hydrogen fluoride adsorbent in the smelter’s dry scrubber also adsorbs water from humid air. Published work in Metals in 2020 measures the adsorbed fraction as moisture on ignition between 25 and 300 degrees Celsius, puts the typical range at 1.5 to 4 percent, and records values exceeding 4 to 5 percent for plants in hot and humid areas or in summer, with an adsorption enthalpy of 4 to 13 kJ/mol. A parcel loaded near the bottom of the schedule’s 0 to 5 percent moisture band can therefore arrive near the top of it with no rain having reached the cargo at any point.

The consequence at the receiving end is chemical rather than commercial. Water entering the reduction cell hydrolyses fluoride, and the same work attributes roughly 10 to 25 percent of the hydrogen fluoride in raw cell fume to moisture carried in with the alumina. That is why a smelter specifies moisture on ignition and why a wet parcel is a quality event and not merely a weight one.

A wetting event proper is worse and the Code says so in four words: if wet, alumina is unpumpable. Caked alumina cannot be drawn through a vacuum or pneumatic suction line, so rain during loading or a leaking hatch cover produces a discharge failure through caking at the far end rather than a stain. Hold ventilation practice generally is covered in marine cargo hold ventilation .

Discharge

Alumina discharges by grab, by pneumatic or vacuum unloader, or by shipboard self-discharging systems, and the choice is a cargo quality decision as much as a rate decision. The DISCHARGE field reads No special requirements, so none of what follows is a Code obligation.

Matching the discharge system to the ship and the cargo

Shore cranes with grabs are slower on a fine powder and leave more residue in the hold corners for hand or bulldozer work. Pneumatic and vacuum systems draw the powder through suction pipes directly into shore silos and deliver it continuously into the smelter feed line. Dedicated alumina tonnage carries the system on board, using aerated sloping hold bottoms feeding a central suction pipe with twin re-loader tanks working in tandem for near-continuous flow, an arrangement related to the self-unloading bulk carrier type. The marine cargo handling cranes and derricks article covers the ship’s own gear.

The quality dimension is the one that reframes the choice. Pneumatic conveying breaks alumina particles and raises the fines fraction: Bruks Siwertell has reported up to 5 percent fines after pneumatic discharge against 0.2 to 0.3 percent with a screw-type unloader. Fines cost the receiver in dry-scrubber loading, feeder flowability and dust loss, so the faster system is not automatically the better one for the cargo.

Plan on realised rates rather than nameplate. Vendor-published operating records run well below machine capacities: a Bruks Siwertell road-mobile unloader at Ploce averaged near 120 tonnes per hour across more than 1,250,000 tonnes and 10,550 hours, and the unit delivered to Trimet France at Marseille at the end of 2021 is rated at 130 tonnes per hour for vessels up to 10,000 dwt, while port-based machines run 400 to 600 tonnes per hour.

The mismatch between ship and terminal is a documented source of dispute. Skuld records a charterer who fixed a vessel without accounting for the differential in hold dimensions and hatch size, so the discharge needed both grabs and bulldozers and took significantly longer than planned, and who then failed to off hire the vessel because both the hold and hatch dimensions had been clearly stated in the fixture correspondence. The lesson sits in the fixture: reconcile the terminal’s gear, the hold access and the hatch openings before the cargo is booked, or the exposure lands in demurrage and laytime .

Hold cleaning, wash water and residues

The one mandatory instruction at this stage is about water. The CLEAN-UP field provides that the water used for cleaning the cargo spaces after discharge shall not be pumped by the fixed bilge pumps, and that a portable pump shall be used as necessary to clear the cargo spaces of the water. IMSBC 3.4.1 also expresses the Code’s preference for hosing down rather than sweeping as a dust control measure during cleaning.

Whether residues and washings may go overside at all is a MARPOL Annex V question rather than an IMSBC one. It turns on the harmful to the marine environment classification the shipper declares under 4.2.2.17 against Annex V appendix I, with implementation guidance in resolution MEPC.295(71), the 2017 Guidelines, adopted on 7 July 2017. The discharge conditions themselves sit in MARPOL Annex V garbage discharge . Removing as much dry residue as possible at the discharge port, in accordance with the Annex and local port rules, reduces both the disposal cost and the exposure before the next load port.

Quantity determination and shortage claims

Alumina is settled on draft survey more often than its unit value justifies, and the arithmetic is unforgiving. Survey accuracy is about 0.5 percent on a large bulk carrier under ideal conditions and 0.75 to 1.0 percent on a Handysize of 25,000 to 40,000 dwt, which is the band much alumina moves in, as set out in draft survey for bulk cargo .

Put a value on that tolerance. On a 40,000 tonne parcel at USD 590 per tonne, the average unit value of US alumina imports on an f.a.s. basis for the first eight months of 2025, one percent is 400 tonnes and about USD 236,000. Alumina is among the highest unit value minor bulk cargoes routinely settled by draft survey, so the same percentage error that is tolerable on coal is not tolerable here.

There is a second divergence that is legitimate rather than an error. Because the cargo adsorbs moisture in transit, a mass-based shore weightometer figure at the load port and a draft survey at the discharge port are not measuring the same cargo. The moisture gained over a tropical voyage is real mass, so a modest gain between load and discharge figures is a property of the cargo rather than evidence of a mis-survey. The bill of lading quantity on a hygroscopic powder needs to be read with that in mind, and deadfreight disputes should be checked against the declared density before the survey is questioned.

Contamination, quality and cargo claims

Contamination of a white cargo is the claim that alumina actually generates, and the defence is built before loading rather than after discharge. The cargo goes straight into a smelter feed system against an impurity specification measured in hundredths of a percent, so a receiver who finds rust scale, paint flakes or residue of a previous cargo has a claim on specification grounds, and the hold that passed its cleanliness inspection at the load port is the owner’s answer to it. The cleanliness grade in the fixture is therefore the standard the cargo will be measured against on delivery.

Moisture is the second driver. Alumina is hygroscopic, so it gains water over a long humid voyage even when loaded dry, and a parcel loaded through a shower or into a wet hold can arrive with caked lumps that foul the receiver’s pneumatic handling. Keeping the holds dry and the covers tight protects the cargo condition and the ship together.

Delay is the third, and it is usually a fixture failure rather than an operational one. Where the claim does arise, the allocation runs through the charter party and the bill of lading regime: the Hague-Visby Rules where they are incorporated, the Inter-Club Agreement apportionment on a time charter, cargo claim time bars , and P&I cover behind it. Investigation practice is covered in marine cargo damage investigation , and the cargo interest’s own cover in cargo insurance and the Institute Cargo Clauses .

Port state control and the regional overlays

A port state officer inspecting an alumina loading checks a documentary chain and nothing more exotic, because there is no moisture certificate and no hold atmosphere to test. The items are the shipper’s cargo information and declaration under SOLAS VI/2 and IMSBC 4.2, the current edition of the Code on board, the loading or unloading plan lodged under SOLAS VI/7.3, the loading booklet under VI/7.2, and the stability information under VI/6.

The governing procedures changed recently. Resolution A.1206(34), Procedures for Port State Control, 2025, was adopted on 3 December 2025 and revokes A.1185(33); as a recommendatory Assembly resolution it carries no entry-into-force date. Regional application runs through the Paris MoU and the Tokyo MoU , with the general regime in port state control .

Three regional overlays are worth naming as overlays rather than as the baseline. In the United States, 46 CFR 148.8 incorporates the IMSBC Code, 2009 edition, by reference, and that incorporation has not been updated to any amendment set, so the version enforceable under 46 CFR part 148 is not the version enforceable under SOLAS; in practice part 148 addresses hazardous materials and Potentially Dangerous Materials, so a Group C alumina cargo falls outside it. In the European Union, Directive 2001/96/EC governs the loading and unloading interface through the BLU Code, and washings landed ashore fall under Directive (EU) 2019/883 on port reception facilities. In Australia, Marine Order 34 (Solid bulk cargoes) 2016, made by AMSA under the Navigation Act 2012, commenced on 1 January 2017 and gives the Code effect in Australian law.

Alumina in the bauxite to aluminum chain

Alumina moves by sea because the three stages of the aluminum chain happen in different places, and each stage roughly halves the mass. Bauxite is mined, refined to alumina near the mine or at a coastal refinery, and the alumina is shipped to smelters sited where electricity is cheap. USGS gives the material balance as a rule of thumb: roughly 4 tonnes of dried bauxite is required to produce 2 tonnes of alumina, which in turn can be used to produce 1 tonne of aluminum. Shipping alumina rather than bauxite to a distant smelter therefore moves half the tonnage for the same metal output.

Production, trade scale and load ports

World alumina production was 142 million tonnes in 2024 and an estimated 150 million tonnes in 2025, according to USGS Mineral Commodity Summaries 2026, on a calcined equivalent weight basis. China dominates at 85.5 million tonnes in 2024 and an estimated 93 million tonnes in 2025, followed by Australia at 17.1 million tonnes and an estimated 17.0 million, and Brazil at 10.6 million and an estimated 11.0 million.

World production is a poor proxy for the seaborne trade, and the reason is China: at roughly 62 percent of world output in 2025, almost all of it feeding domestic smelters, Chinese production barely touches the water. The seaborne flow runs from the export refineries to the smelter coasts. On 2025 estimates the refinery side is Australia at 17.0 million tonnes, Brazil at 11.0, India at 8.2, Russia at 2.9, the UAE at 2.3, Saudi Arabia at 1.9, Ireland at 1.7, and Jamaica, Vietnam, Indonesia, Kazakhstan and Canada at about 1.5 each, with the United States at 0.71 million tonnes from Gramercy, Louisiana. The discharge side follows cheap power: the Gulf states, Iceland and Norway, Quebec, Mozambique and South Africa, New Zealand, Malaysia and Indonesia. Port infrastructure detail sits in container and bulk terminals and world port profiles .

Two 2025 developments bear on future flows with a lag. Mining began in June 2025 within expanded boundaries near Boddington in Australia, feeding a 4.7 million tonne per year refinery near Collie. And in August 2025 the Government of Guinea revoked bauxite mining licences from the subsidiary of a UAE-based aluminium producer after a dispute over refinery construction, reallocating the concessions to a state-backed company.

Ship sizes and the neighbouring schedules

Parcels of 25,000 to 55,000 tonnes on smelter berths rather than major bulk terminals put alumina on geared Handysize, Supramax and Ultramax tonnage, which is why alumina appears explicitly in the Supramax cargo book. A minority moves on dedicated pneumatic self-dischargers, sized to the receiving smelter’s preference for continuous delivery.

The chain also explains why several aluminum-related cargoes appear in the Code with different classifications. Bauxite, the raw ore, has a coarse Group C form and a fines form liable to dynamic separation, and the bauxite schedule covers both. Alumina is the inert Group C powder described here. The contrast worth drawing is with cement , the other major Group C white powder a bulk carrier loads: both are dusty, flowable and pneumatically discharged, but cement hydrates and hardens on contact with moisture while alumina stays a free powder that merely cakes. Other fine-powder and mineral neighbours in the same fleet include soda ash , gypsum , limestone , barytes , salt , potash , phosphate rock , petroleum coke , urea , sulphur , cement clinker and mineral concentrates . The wider families are set out in IMSBC Group B cargoes and IMSBC Group C cargoes .

Limitations

This article is a practitioner reference and not the regulation. The authoritative document for any specific shipment is the in-force IMSBC Code individual schedule for the Bulk Cargo Shipping Name actually declared, read with the shipper’s cargo declaration for that consignment. The data here matches the schedule as amended by resolution MSC.539(107), amendment 07-23, which is mandatory until 31 December 2026; amendment 08-25, resolution MSC.575(110), becomes mandatory on 1 January 2027 and may be applied voluntarily before then, and whether it alters any alumina entry should be checked against that resolution directly.

Two boundaries of the schedule data itself matter. The bulk density and stowage factor are informative rather than mandatory under IMSBC 1.4.2, and they are schedule ranges rather than the figure for a particular parcel, so the density that governs a stowage and stability calculation is the one the shipper declares. And where the declared name is ALUMINA HYDRATE rather than ALUMINA, the cargo is Group A and B with a liquefaction hazard and none of the Group C handling described above applies.

The discharge rates, fines figures and hold cleanliness grades quoted here are drawn from equipment vendor publications and from P&I loss prevention material rather than from any instrument, so they describe practice and not obligation. No authoritative free series breaks out seaborne alumina trade volume, so this article gives production and refinery capacity rather than trade, and the load and discharge geography is inferred from refinery and smelter locations rather than from a published trade matrix. Occupational exposure limits are not stated because no alumina-specific international limit exists and the values in circulation are for aluminium metal and its insoluble compounds or are national particulate limits. The master’s judgement on cargo condition, hold readiness and weather governs the operation, and national port regulations and the receiving terminal’s own dust and water discharge rules may add requirements beyond the schedule.

Related Articles

• IMSBC Code
• IMSBC Group C cargoes
• Bauxite: IMSBC Code Schedule and Carriage
• Cement: IMSBC Code Schedule and Carriage
• Cargo hold preparation standards
• Bulk carrier
• Draft survey for bulk cargo
• BLU Code and BLU Manual