Phosphate Rock: IMSBC Code Schedule and Carriage

Phosphate rock shipped in bulk is regulated by the IMSBC Code under two separate schedule entries: PHOSPHATE ROCK (CALCINED), classified Group C, and PHOSPHATE ROCK (UNCALCINED), which is Group C for coarse dry product but Group A for finely ground or moist material that can liquefy under ship motion. The dominant practical hazards are heavy dust generation during all cargo-handling operations and, for the uncalcined grades, the liquefaction risk that requires Transportable Moisture Limit certification before loading.

Phosphate rock is one of the oldest continuously traded dry bulk cargoes and one of the few commodities with no synthetic substitute: every tonne of phosphorus applied to agricultural soils worldwide traces back to mined phosphate rock. Global seaborne trade runs at roughly 30 to 35 million tonnes per year. The cargo moves from a concentrated geography of exporting nations, principally Morocco, Russia, Jordan, and Saudi Arabia, to fertilizer-manufacturing markets in India, Brazil, Europe, and North America. Unlike many industrial minerals, the ultimate market is food production, which gives the trade its particular price sensitivity and shapes the long-term structure of the producing industry.

The IMSBC Code, made mandatory under SOLAS Chapter VI by Resolution MSC.268(85) in January 2011, controls the safe carriage of phosphate rock in two schedule entries that reflect real differences in physical behaviour between the product forms traded commercially. Getting the group classification right matters: a vessel that loads uncalcined fine-ground phosphate rock at elevated moisture content without TML certification is loading a potential liquefaction cargo under the same conditions that have contributed to bulk carrier losses across other commodity categories.

The fertilizer feedstock trade

Phosphate rock, also called phosphorite in geological literature, is a sedimentary or igneous mineral resource consisting primarily of the calcium phosphate mineral group known as apatite. The dominant commercial mineral is fluorapatite, Ca5(PO4)3F, though carbonate-bearing varieties (francolite) are the primary mineral in many of the world’s largest sedimentary deposits, including the extensive Cretaceous-age phosphorite sequences in Morocco, Western Sahara, and Tunisia. The Kola Peninsula deposits in Russia, by contrast, are of igneous origin and consist of apatite-nepheline ore with substantially different mineralogical and handling characteristics.

The phosphorus pentoxide (P2O5) content of the apatite mineral, usually reported as the “BPL” (bone phosphate of lime) grade on older specifications or as the P2O5 percentage directly on modern certificates, determines commercial value. High-grade sedimentary rock from Morocco’s Beni Idir and Sidi Chennane deposits typically grades at 32 to 34 percent P2O5. Lower-grade products from Egypt and parts of North Africa may run at 28 to 30 percent P2O5. The Kola apatite concentrate, processed by flotation from the apatite-nepheline ore, consistently achieves 39 to 40 percent P2O5, making it the highest-grade traded product in the seaborne market.

Phosphate rock is the raw material for three primary end products. Phosphoric acid (H3PO4) is produced by reacting rock with sulfuric acid in the “wet process,” which is the dominant industrial route and generates phosphogypsum as a byproduct. Superphosphate and triple superphosphate fertilizers are produced by acidulating rock with sulfuric acid or phosphoric acid respectively, dissolving the apatite and producing water-soluble phosphate. Elemental phosphorus is produced by electric-furnace reduction, a route largely confined to China and Eastern Europe that consumes higher-grade rock. Each end-use imposes different quality specifications on the rock, and cargo declarations reflect those specifications in the P2O5, SiO2, Fe2O3, Al2O3, MgO, and F content.

The seaborne fertilizer supply chain shows a steady long-term shift. Morocco’s state mining company OCP Group has invested aggressively in on-site phosphoric acid and fertilizer manufacturing since the 2000s, so an increasing share of Moroccan phosphate exports moves as processed phosphoric acid or as diammonium phosphate (DAP) and monoammonium phosphate (MAP) fertilizers rather than as raw rock. Diammonium phosphate, for example, is a finished fertilizer with its own distinct IMSBC schedule entry. However, raw rock exports from Morocco remain substantial, particularly to Indian fertilizer plants that process their own acid, and the rock trade at Jorf Lasfar and Safi continues at significant volumes.

IMSBC Code schedule structure for phosphate rock

The IMSBC Code’s Appendix 1 contains individual schedule entries for phosphate rock and closely related phosphate mineral products. The principal entries relevant to bulk rock shipments are:

The “A or C” notation for uncalcined rock is not ambiguous in practice: it reflects a genuine physical difference between product forms. Coarse, dried product that behaves like a granular solid is Group C. Finely beneficiated or wet-screened product that can hold moisture in its pore structure above the TML threshold is Group A. The shipper bears the legal obligation to determine and declare the correct group for the actual cargo presented at the loading berth.

The two main phosphate rock schedule entries differ fundamentally in physical behaviour, hazard profile, and the documentary requirements placed on the shipper before cargo can legally be loaded.

PHOSPHATE ROCK (CALCINED): Group C schedule

Calcination is a thermal treatment process in which phosphate rock is heated to temperatures typically between 700 and 900 degrees Celsius. The heat drives off moisture, decomposes carbonate gangue minerals, and partially oxidizes organic matter. The resulting product is dry, hard, and substantially less prone to moisture retention than the run-of-mine or beneficiated feed. Bulk density of calcined rock is approximately 1.5 to 2.0 tonnes per cubic metre, with a stowage factor of roughly 0.50 to 0.65 cubic metres per tonne, though the exact values depend on feed rock type and calcination conditions.

The IMSBC Code classifies PHOSPHATE ROCK (CALCINED) as Group C, meaning it does not liquefy and presents no significant chemical hazard. This classification reflects the physical reality: the calcination process removes the moisture that drives Group A liquefaction risk, and the fired material’s grain structure is stable under the dynamic loading of a sea voyage. No TML certificate is required for calcined rock, and shippers do not need to provide a moisture content declaration as a precondition for loading (though practical cargo documentation still includes weight and quality certificates).

Dust is the primary operational concern with calcined rock. The calcination process breaks down some of the softer carbonate material in the gangue, producing a product that can be friable and fine-generating during conveyor handling, loading, and discharge. Phosphate dust is not acutely toxic but causes respiratory irritation with prolonged exposure, and calcined rock dust carries the NORM considerations discussed later in this article. The IMSBC Code’s handling notes for the calcined schedule require that dust control measures be in place during loading and discharge operations and that crew wear appropriate respiratory protection when cargo surfaces are disturbed.

Group C cargoes require no special stability precautions beyond the standard dry bulk carriage rules, but the high bulk density of calcined rock means that volumetric calculations for hold filling and trim management are material. At 1,500 to 2,000 kg/m3, calcined rock is denser than grain or coal but lighter than typical metal ores, placing it in the mid-range of dry bulk density.

PHOSPHATE ROCK (UNCALCINED): the Group A/C distinction

Uncalcined phosphate rock is the direct product of mining and, in many cases, beneficiation by washing, scrubbing, and screening, without the thermal treatment step. Two commercial forms matter for the IMSBC classification:

Coarse run-of-mine or screened pebble-grade rock: material retained on a screen at typically 1 to 2 mm and above, often called “phosphate pebbles” in trade. This product has a relatively low fines content, good drainage, and low moisture retention. At normal commercial moisture levels it does not liquefy and qualifies as Group C. The ROCK PHOSPHATE (PEBBLES) schedule in the IMSBC Code specifically covers this product form.

Finely ground or wet-screened beneficiation product: material that has been milled to below 1 mm, or fine-fraction screened product from washing circuits, where the minus-75-micrometre fraction is significant. This product retains process moisture in its fine inter-particle pores and can exhibit flow behaviour under cyclic loading when moisture content exceeds the Transportable Moisture Limit. This form qualifies as Group A under the IMSBC Code.

The practical distinction between the two forms comes down to particle size distribution and moisture content at loading. Where a significant proportion of the cargo passes through a 75-micrometre sieve and the cargo has been in contact with water during processing, the shipper must arrange TML testing and provide a current moisture content certificate. The IMSBC Code requires that these documents be provided to the master before loading commences, and the master must not accept Group A cargo where the certified moisture content equals or exceeds the TML.

The Group A liquefaction hazard in uncalcined phosphate rock

Physical mechanism

Cargo liquefaction in fine-grained bulk cargoes is not a dramatic or sudden process in most cases. It begins at the base of the cargo mass in a loaded hold, where overburden stress is highest and drainage is slowest. As the ship rolls and pitches at sea, each motion cycle compresses the wet fine cargo and generates a small increment of pore-water pressure. Over many thousands of cycles, the pore pressure builds up faster than water can drain through the fine matrix. When the accumulated pore pressure equals the effective overburden stress, the particle-to-particle contact forces fall to zero and the cargo transitions from a coherent solid mass to a dense fluid slurry.

A liquefied lower layer allows the overlying solid cargo to slide on each roll cycle. The ship develops a progressive list, and if the solid cargo above the liquefied base shifts to one side, the list becomes self-reinforcing. The crew may see bilge levels rise as water migrates downward through the liquefied zone, but the surface of the cargo in the hold often appears dry and solid above a fully liquefied lower layer. Bridges on bulk carriers have reported no obvious visual warning before a list became critical. This concealed progression is what makes the liquefaction hazard dangerous for cargoes where group classification is misapplied.

The IMSBC Code Section 7 addresses Group A cargoes specifically, requiring TML testing by one of three prescribed methods: the flow table test, the penetration test, or the Proctor-Fagerberg test. The TML is set at 90 percent of the Flow Moisture Point (FMP) for the flow table and penetration methods:

For the Proctor-Fagerberg method, the TML is derived from a compaction-saturation curve at 70 percent degree of saturation. TML certificates must be renewed at intervals not exceeding six months before loading, and the shipper must provide a certificate of the actual moisture content of the cargo at loading, confirming it is below the TML.

Shipboard can test as a screening tool

The IMSBC Code prescribes a simple shipboard screening procedure known as the can test for Group A cargoes. A 0.5 to 1-litre sample is placed in a cylindrical container and dropped from 0.2 metres onto a hard surface 25 times at one- to two-second intervals. If free moisture appears on the surface of the sample, the cargo is suspect. A can test showing free moisture means the master should halt loading and seek independent laboratory analysis before proceeding.

The can test is a screening tool, not a substitute for certified laboratory TML determination. A dry can test result does not confirm that the cargo moisture is below TML; laboratory-measured FMP is required for a definitive assessment. For uncalcined phosphate rock, the can test provides useful shipboard surveillance when documentation is incomplete or when cargo condition changes during a multi-day loading operation due to rainfall or changes in the surface of stockpiled material.

The IMSBC TML Moisture Check calculator allows master and mate to verify the safe loading margin between the certified moisture content and the TML before cargo operations begin.

Declared cargo and group mismatch risk

A recurring concern in Group A cargo enforcement is the pressure on shippers to declare fine-grained wet product as Group C to avoid TML testing costs and delays. Phosphate rock is not immune to this pressure. Wet beneficiation circuits at some mines produce fines fractions that, if loaded without drying, would clearly exceed TML. If those fines are blended with coarser dried product and declared as Group C without individual lot testing, the mixed cargo may contain pockets of moisture-rich fine material that behave as Group A under ship motion.

Flag state authorities and port state control surveyors at receiving ports check cargo declarations against the physical appearance of the cargo and the loading port moisture conditions. Shippers who declare uncalcined fine rock as Group C without proper testing are exposed to port state control action, P&I club coverage issues, and criminal liability under national shipping laws in the event of a cargo-related incident.

Dust hazard during loading and discharge

Dust is the dominant day-to-day operational concern for both calcined and uncalcined phosphate rock cargoes, and it affects every stage of the cargo cycle from stockpile handling at the loading terminal to discharge conveyor and crusher operations at the receiving plant.

Sources and character of phosphate dust

Fine phosphate rock dust is generated wherever the cargo is mechanically disturbed. The free-fall distance from a shiploader spout into a hold can be 20 to 40 metres during the early stages of loading before the cargo surface builds up, and this fall entrains air and disperses the finest particles as a dust cloud that rises through the hatch opening and drifts downwind. The dust fraction is typically below 100 micrometres aerodynamic diameter; the respirable fraction below 10 micrometres can penetrate to the alveolar level in exposed workers.

Phosphate rock dust is not classified as acutely toxic under international maritime dangerous goods rules, and it does not pose the flammability hazard of some organic dusts. However, prolonged inhalation causes respiratory tract irritation, and the NORM content of the dust, described separately below, means that repeated high-exposure episodes carry a low but non-zero internal radiation dose component. The IMSBC Code requires that dust-generating cargo operations be controlled and that crew working near open hatch openings during loading wear dust masks rated for mineral dust, at minimum a half-face respirator with a particulate filter rated to EN 149 FFP2 or NIOSH N95 equivalent.

Terminal dust management

Modern phosphate terminals in Morocco, Saudi Arabia, and Jordan use enclosed or partially enclosed conveyor systems with local exhaust ventilation at transfer points. Loading spouts are fitted with telescopic sleeves that extend into the hold as the cargo surface builds up, reducing the free-fall distance and the dust entrainment rate. Water spray bars at the shiploader head suppress dust at the point of fall without adding enough moisture to material the actual cargo moisture content meaningfully.

Older or smaller terminals in some exporting regions continue to use open belt conveyors without hood covers and fixed-height loading chutes. At these terminals, dust control depends on weather conditions (light rain suppresses dust; dry wind spreads it) and on manual water spray application. During dust-intensive loading periods, vessel crews should close all deck-level HVAC intakes on the windward side and deploy door seals to keep cargo spaces clear of fine dust.

Discharge at fertilizer plants often involves grab cranes or pneumatic unloaders. Grab operations on dusty rock drop the cargo from the jaws at height and generate secondary dust clouds; pneumatic systems entrain dust in the transfer air stream and require filtration at the plant’s air-discharge point. In either case, the cargo manifold area of the vessel remains dust-affected throughout discharge, and crew working on deck should maintain respiratory protection.

Naturally occurring radioactive material (NORM)

The geochemical basis

Phosphate rock contains naturally occurring radioactive material because the sedimentary apatite mineral incorporates uranium and its daughter radionuclides during formation. Ancient phosphate deposits formed from upwelling ocean currents that concentrated phosphate and uranium from seawater in the same sedimentary layers. The uranium-238 decay chain, which includes radium-226 and radon-222 among its progeny, is present in measurable quantities in all sedimentary phosphate rock. Thorium-232 is present at lower concentrations in most sedimentary phosphate.

Commercial phosphate rock from Moroccan, Jordanian, and Egyptian deposits typically contains uranium at 50 to 100 ppm by weight, with associated radium-226 concentrations on the order of 1,000 to 2,000 becquerels per kilogram (Bq/kg). These activity concentrations are above the natural background level of unweathered siliceous rock (typically below 50 Bq/kg for uranium series in granite) but well below the activity concentrations that would trigger classification as radioactive material under the International Maritime Dangerous Goods (IMDG) Code. The IMDG Code exemption threshold for radioactive material classification is 70 Bq/g (70,000 Bq/kg) for uranium-natural, which is orders of magnitude above typical phosphate rock concentrations. Ordinary phosphate rock shipments are not radioactive cargo under international maritime law.

Crew exposure pathways

Three exposure pathways are relevant for vessel crews on phosphate rock carriers. External irradiation from the cargo mass is negligible: the dose rate at one metre above a bulk cargo surface with radium-226 activity of 1,500 Bq/kg is well below 0.1 microsievert per hour, which is comparable to elevated natural background radiation at altitude and is not a significant occupational dose pathway for the typical cargo voyage of 10 to 20 days.

Inhalation of radioactive dust is the more relevant pathway. If a crew member is exposed to fine phosphate dust for extended periods without respiratory protection, the inhalation of radium-226 and lead-210-bearing particles delivers a committed effective dose to the lung tissue. The IAEA Safety Reports Series No. 78 addresses this pathway in detail for workers at phosphate processing facilities, where the exposure duration is year-round rather than per-voyage. For vessel crews, the duration of exposure to open-hold dust conditions is limited to loading and discharge port stays, typically measured in hours to a few days per voyage. At reasonable dust control standards, the incremental dose from phosphate rock handling is low relative to other occupational exposures.

Radon (Rn-222) exhalation from the cargo is a third pathway. Radium-226 decays to radon gas, which can diffuse out of the cargo mass and accumulate in enclosed spaces such as the lower-hold void or a poorly ventilated cargo hold. The IMSBC Code’s provisions for atmospheric testing of cargo spaces before entry address this, and the recommendation to ventilate cargo holds before crew entry applies to any cargo that can generate oxygen depletion or accumulate gases.

Regulatory status and practical guidance

Phosphate rock does not require NORM-specific documentation under current versions of the IMSBC Code. The Code does not carry a specific NORM classification system comparable to the IMDG Code’s radioactive material classes. The IAEA guidance in Safety Reports Series No. 78 is directed primarily at land-based phosphate industry workers rather than at maritime carriers, and there is no IMO circular mandating NORM monitoring for ordinary phosphate rock bulk shipments.

The practical guidance from P&I clubs and from flag state maritime administrations is consistent: dust control and respiratory protection during cargo operations are the primary protective measures. These measures reduce inhalation exposure across all relevant dust hazards, including NORM, and are already required by the IMSBC Code’s general cargo-handling provisions. There is no current requirement to treat a standard phosphate rock bulk shipment as a radioactive cargo or to conduct dose-rate monitoring on the vessel.

Physical properties relevant to bulk carriage

The physical properties of phosphate rock vary between the calcined and uncalcined forms and across the range of commercial product grades. The following values represent typical ranges for mainstream commercial products; actual values for a specific cargo must be taken from the shipper’s cargo declaration and certificate of analysis.

The stowage factor of uncalcined fines concentrate at 0.63 to 0.83 m3/t is similar to that of bauxite and iron ore, placing phosphate rock fines in the moderately dense range of dry bulk cargoes. The bulk density is low enough that loading a full-draft Panamax bulk carrier with phosphate rock concentrate is straightforward without exceeding tank-top limits, unlike very dense cargoes such as iron ore pellets or ilmenite sand.

For calcined rock, the reduced moisture content and the harder, less friable grain structure compared to wet uncalcined product mean that the cargo is stable and free-flowing. It angles of repose in the 30 to 38 degree range allow reliable trimming and good self-leveling behaviour when loaded by conveyor.

Major producers and the seaborne trade

Morocco: OCP Group and the Atlantic export infrastructure

Morocco holds the world’s largest phosphate rock reserves, estimated by the US Geological Survey at approximately 50 billion tonnes, which is roughly 70 percent of global identified reserves. OCP Group, wholly owned by the Moroccan state, operates mines at Khouribga, Gantour, and Ben Guerir and exports through three dedicated phosphate terminals: Jorf Lasfar (the largest, capable of handling Capesize-class vessels at its deep-water berths), Safi (the original phosphate port, now handling smaller vessels and DAP exports), and Casablanca (handling smaller lots and some processed product). Annual OCP phosphate rock production exceeded 38 million tonnes in recent years, though the proportion exported as raw rock versus processed products has shifted steadily toward value-added phosphoric acid, DAP, and MAP.

Moroccan phosphate rock from sedimentary Cretaceous and Eocene deposits is typically a soft, chalky carbonate-rich ore, which makes it relatively easy to mine and beneficiate but also means it generates a higher proportion of fines during processing than harder igneous-origin rock. The beneficiated product from OCP’s washing and flotation circuits is a fine-grained material. Whether it qualifies as Group A or Group C depends on the specific product fraction shipped and the moisture at loading.

Russia: Kola Peninsula apatite concentrate

Russia’s phosphate export comes primarily from the Kola Peninsula, where Phosagro (previously part of the Apatit joint venture) processes apatite-nepheline ore by flotation to produce a concentrated apatite product grading at approximately 39 to 40 percent P2O5. This material is an igneous apatite crystal concentrate, substantially different from the fine sedimentary product shipped from Morocco. The particle size of Kola apatite concentrate is controlled by the flotation circuit, typically with a median particle size around 0.1 to 0.3 mm. Moisture content after filtration is approximately 12 to 16 percent.

Kola apatite concentrate exports through Murmansk, where dedicated phosphate handling infrastructure manages the cargo. The combination of relatively high moisture content and fine particle size means this product is assessed as Group A under the IMSBC Code, and TML certification is required for each shipment. The annual export volume has historically been in the range of 8 to 10 million tonnes, going principally to Finnish and Eastern European fertilizer plants.

Jordan, Saudi Arabia, and the Middle East

Jordan’s phosphate mining is operated by the Jordan Phosphate Mines Company (JPMC), a semi-state entity that mines at Al-Abiad, Eshidiyya, and Rusaifa and exports through the port of Aqaba on the Red Sea. Jordan’s production runs at approximately 8 to 9 million tonnes per year, with exports of rock and processed phosphoric acid. The product from Jordanian mines is a medium-grade sedimentary rock, typically 30 to 32 percent P2O5.

Saudi Arabia’s Ma’aden Phosphate Company (a joint venture of Ma’aden and Mosaic) operates an integrated mine-to-fertilizer complex in the northern region (Al Jalamid mine, Wa’ad Al Shamal industrial city, Ras Al-Khair port on the Arabian Gulf). The complex produces DAP and MAP as primary export products, with some rock export as well. The port of Ras Al-Khair has been purpose-built for the phosphate complex with dedicated bulk loading berths.

Egypt (through El Nasr Mining Company and private operators at Sebaiya and Abu Tartur) and Tunisia (through Compagnie des Phosphates de Gafsa, CPG) export smaller volumes of rock through Mediterranean ports, with Egypt’s Ain Sukna and Tunisia’s La Skhirra as primary loading points.

China: domestic consumption exceeds export

China is the world’s largest phosphate rock producer by volume, with output in the range of 80 to 90 million tonnes per year from Yunnan, Guizhou, Hunan, and Sichuan provinces. However, Chinese rock is primarily consumed domestically to feed one of the world’s largest phosphate fertilizer industries. Seaborne rock exports from China have fallen sharply since 2010 as domestic fertilizer demand and environmental restrictions on mine operations have reduced available export surplus. China applies export tariffs on phosphate rock as a domestic supply-protection measure, and these tariffs have at times been set at levels that effectively close rock exports to all but the highest-grade products.

Hold preparation and loading operations

Hold preparation standards

Hold preparation for phosphate rock is less demanding than for some cargo categories but still requires systematic attention. The holds must be clean and dry; residues from previous cargoes including coal, grain, fertilizer, or any cargo that would contaminate phosphate rock and affect its fertilizer-grade specification must be removed. Rusty bilge hoppers and hold frames are acceptable because phosphate rock is not corrosive to mild steel and the iron contamination from loose rust is negligible relative to the cargo volume, but holds must be swept thoroughly and bilge covers must be seated correctly to prevent fine material from entering bilge wells.

Bilge system operability is important for phosphate rock voyages. Fine phosphate dust moistened by bilge water or rainfall can form a thick paste that blocks bilge strainer ports and pump suctions. Chief officers on vessels with a history of phosphate cargoes should inspect bilge strainer ports before loading and clear any residual buildup from previous voyages. During the voyage, daily bilge soundings should be taken; an unexpected rise in bilge levels may indicate that fine material is working down through the hatch seals or that seawater ingress is moistening the cargo. Either scenario warrants investigation before the cargo moisture rises.

The IMSBC Code does not require specific surface coatings or chemical treatments to holds before loading phosphate rock, and in practice none are applied. The Code’s cleanliness standard for Group C cargoes is that holds be clean and dry, without residues from previous cargoes that would contaminate the cargo or affect the vessel’s structure, and that all bilge systems be operable.

Cargo hold inspection and surveying

Pre-loading hold inspection by a cargo surveyor is standard practice for phosphate rock shipments, particularly for long-term trading contracts where the shipper’s and charterer’s P&I clubs both have an interest in cargo quality preservation. The surveyor checks hold cleanliness, bilge system operability, hatch cover condition, and any structural defects in the hold that could allow water ingress. A hold cleanliness certificate is issued before loading begins.

For Group A uncalcined rock shipments, the master should receive from the shipper before or at the time of cargo declaration:

• A certificate of TML, issued by a laboratory accredited to conduct IMSBC Code Appendix 2 tests, dated within six months of loading
• A certificate of actual moisture content of the cargo at loading, confirming that moisture is below TML
• The cargo declaration in the format prescribed by Section 4 of the IMSBC Code, including the declared IMSBC group, the Bulk Cargo Shipping Name, the physical and chemical properties, and the stowage and handling instructions

If any of these documents are missing or show moisture content at or above TML, the master must not allow loading to proceed. This is a non-negotiable obligation under SOLAS Chapter VI and the IMSBC Code, and no commercial pressure from the shipper, charterer, or port authority overrides it.

Loading rate and trim

Phosphate rock is typically loaded by shore conveyor and shiploader at rates of 1,500 to 5,000 tonnes per hour at major terminals, with the rate depending on terminal equipment capacity and vessel hold configuration. Jorf Lasfar’s largest shiploaders can achieve rates above 4,000 t/h on large bulk carriers, allowing a full Panamax cargo of approximately 70,000 tonnes to be loaded in 18 to 22 hours with a single loader.

Trim management during loading is straightforward for coarse grades. The cargo self-levels adequately in each hold if loaded from a centered spout or trimmed by a traveling shiploader. Finer grades, particularly wet uncalcined concentrate, may require mechanical trimming by bulldozer to spread the cargo and prevent peak loads from forming under the loading point. The Code notes in the handling section for fine phosphate products that the trimming requirements should be addressed in the cargo handling plan.

For vessels loading phosphate rock at multiple holds simultaneously, draft and trim calculations should be updated throughout loading to ensure the vessel remains within its stability and structural stress limits. The high bulk density of calcined rock compared to, say, grain means that the vessel reaches its maximum draft at a lower volumetric fill fraction, and the distribution between holds affects the longitudinal bending moment.

Discharge and cargo residues

Discharge operations

Discharge of phosphate rock at fertilizer plant berths is most commonly by shore grab cranes, which take large bites of cargo from the open hold and deposit it on shore conveyors feeding covered storage sheds or open stockpiles. Grab discharge generates repeated dust bursts as each load is released at height, and wind conditions during discharge affect how much fugitive dust escapes the berth area.

At some terminals, particularly for fine-grade material destined for direct-feed to phosphoric acid plants, pneumatic ship unloaders are used. These systems use high-velocity air to convey fine rock through a pipe from the hold to the shore silo, eliminating the dust problem from open grabs but requiring effective filtration at the terminal air-discharge point. The unloading rate of pneumatic systems at 100 to 500 t/h is lower than grab rates, so the discharge takes longer per tonne, but product loss and contamination are minimized.

During discharge by grab, careful monitoring of the draft and list is good practice. Phosphate rock has adequate cohesion when slightly moist to stand in vertical faces within the hold during grab discharge. Very fine dry product may run toward the center or corners under vibration from the cranes; deck crew should monitor for uneven distribution forming within the hold.

Cargo residues

Phosphate rock does not pose significant hold residue challenges for the subsequent voyage. The cargo is not water-soluble to any degree that would affect the vessel’s structure, it does not leave reactive residues, and it does not contaminate mild steel with corrosive deposits. A normal sweeping of the hold after discharge, followed by washdown with seawater or freshwater and bilge pump operation, brings the hold to an acceptable cleanliness standard for most subsequent cargoes.

One exception applies where the next cargo is a food-grade or high-specification product requiring holds free of mineral contamination. In those cases, a freshwater wash followed by hold inspection and certificate may be required, and if Kola apatite concentrate (which contains minor amounts of nepheline and other gangue minerals) was the previous cargo, additional attention to bilge areas where fine concentrate settles is warranted.

The residual NORM consideration is minor in practice. Phosphate rock does not leave detectable radioactivity on hold surfaces above background levels after a normal discharge and washdown. There is no regulatory requirement for radiation surveys of holds after phosphate rock discharge under either the IMSBC Code or the IMDG Code for standard commercial phosphate rock products.

Companion calculators

The IMSBC Phosphate Rock calculator and the IMSBC Rock Phosphate Pebbles calculator provide schedule reference data, stowage factor estimates, and cargo property lookup for these specific IMSBC schedule entries.

The IMSBC TML Moisture Check calculator is the relevant tool when verifying that an uncalcined Group A shipment is within the safe moisture range before loading commences.

For reference data on the phosphate fertilizer products derived from phosphate rock, the IMSBC DAP calculator and the IMSBC Defluorinated Phosphate calculator provide the corresponding schedule data for those downstream products.

Limitations

The IMSBC Code group classification for phosphate rock, particularly the Group A/C boundary for uncalcined material, depends on the actual particle size distribution and moisture content of the specific cargo presented at the loading berth. The general ranges in this article are illustrative of commercial practice; they do not substitute for shipper-provided TML test certificates and moisture content declarations for any individual shipment. TML test results are cargo-specific and can vary between batches from the same mine depending on seasonal moisture conditions, crushing parameters, and blending practice.

The NORM discussion in this article reflects the radiological characteristics of mainstream sedimentary phosphate rock cargoes from Morocco, Jordan, Egypt, and Saudi Arabia. Igneous-origin rock from Kola has a different mineralogy and its NORM profile differs from sedimentary rock; consult the shipper’s material safety data sheet for specific activity concentration data on any cargo. No information in this article constitutes radiation protection advice for a specific voyage; operators with concerns about NORM exposure for vessel crews should consult the applicable national radiation protection authority or a qualified health physics consultant.

The seaborne trade volumes cited for specific producing countries reflect publicly available estimates and may differ from official government or company data. Trade flows shift with fertilizer demand cycles, producer investment decisions, and trade policy changes. OCP Group, JPMC, Ma’aden Phosphate, and Phosagro publish annual production and export figures in their financial reports; these are the primary sources for current volumes.

The IMSBC Code itself is the definitive regulatory reference for carriage requirements. Resolution MSC.539(107) adopted Amendment 07-23, mandatory from 1 January 2025, is the current operative version as of the lastmod date of this article. Subsequent IMO Maritime Safety Committee sessions may amend the schedule entries, group classifications, or testing requirements; always consult the current consolidated text of the IMSBC Code through the official IMO publication.

See also

• IMSBC Code
• IMSBC Group A cargoes
• IMSBC Group C cargoes
• Cargo liquefaction
• Diammonium phosphate: IMSBC schedule
• Mineral concentrates: IMSBC schedule
• Sand: IMSBC schedule
• Bauxite: IMSBC schedule
• Cargo hold preparation standards
• Ammonium nitrate fertilizer: IMSBC schedule
• Potash: IMSBC schedule