The term iron ore includes all of the oxides or carbonates of iron occurring naturally.
Iron ore cargoes: Iron ore is likely to be carried in one of four different forms:
• ROM is run of mine, which is ore of no special grade, shipped as it comes from the mine.
• Fines are small screenings of iron ore. They may be sintered, which is a fusing together of fines with coke breeze, millstone and limestone fines to make lumps, or pelletised, round pellets formed of very fine high grade ores.
• Lump is ore larger than a certain size.
• Concentrates are obtained when a natural ore has undergone some form of purification by physical
separation of undesirable ingredients. Concentrates are like heavy sand.
Pre planning the loading:
Iron ore is a high density cargo, with stowage factor ranging from 0.24-0.8 mVtonne. The denser grades require very little space in a hold and when occupying only the bottom of the hold iron ore cargoes lower the ship's centre of gravity and make her very stiff.
There is a variety of ways in which a ship can be damaged by high-density cargoes when badly distributed, and the following errors must be avoided: individual holds must not be overloaded; unsuitable block loading must not be used; excessive shear forces and bending moments must be avoided .
There is a number of operational reasons why it is more efficient to carry heavy cargoes such as iron ore only in alternate holds, a system known informally as 'jump loading', and for this reason many bulk carrier have been classified as 'strengthened for heavy cargoes, (alternate) holds may be left empty'. When so classed, it is permissible to load a full deadweight cargo, using only alternate holds, normally the odd numbered ones.
required when iron ore cargoes are being carried, but three normal precautions can be emphasised. Bilges should be pumped regularly to dispose of water draining from the cargo. Bilges should be sounded regularly to detect any sign that the vessel is leaking and a hold is flooding. Holds should not be entered except when the air has been found to be safe.
Iron ores are self draining. Iron ore loaded in Port Cartier, for example, may in summer be shipped with an average moisture content as high as 5 per cent43, but excess water will drain to the bottom of the hold with about 2.5 per cent being retained in the cargo. Excess water remaining in the hold is likely to cause inconvenience during discharge, so bilges should be regularly pumped dry during the voyage.
To avoid disputes in which cargo shortage is alleged after large tonnages of water have been pumped overboard,
the ship should keep a record of the tonnages of bilge water discharged. These tonnages can be calculated when the ship has bilge calibrations by recording the bilge soundings before and after pumping bilges.
Alternatively, bilges can be pumped to a calibrated tank and sounded therein before discharge.
A number of bulk carriers have foundered when carrying cargoes of iron ore. The foundering may
have been preceded by flooding of holds. Hold bilges should be sounded daily to detect flooding. Flooding will be distinguishable from drainage of water from the cargo by the fact that the increase in sounding will be limited to one or two holds and that it will be more rapid.
Iron ores are liable to oxidise, thus reducing the oxygen in the air. The atmosphere in the hold must be tested to ensure that it is safe before the hold is entered or compressed air breathing apparatus must be worn. There is no requirement to ventilate iron ore cargoes, and practices vary. Some masters keep ventilators closed to exclude rain and spray from the holds. Others ventilate to maintain a healthy atmosphere within the hold.
Iron ore cargoes: Iron ore is likely to be carried in one of four different forms:
• ROM is run of mine, which is ore of no special grade, shipped as it comes from the mine.
• Fines are small screenings of iron ore. They may be sintered, which is a fusing together of fines with coke breeze, millstone and limestone fines to make lumps, or pelletised, round pellets formed of very fine high grade ores.
• Lump is ore larger than a certain size.
• Concentrates are obtained when a natural ore has undergone some form of purification by physical
separation of undesirable ingredients. Concentrates are like heavy sand.
Pre planning the loading:
Iron ore is a high density cargo, with stowage factor ranging from 0.24-0.8 mVtonne. The denser grades require very little space in a hold and when occupying only the bottom of the hold iron ore cargoes lower the ship's centre of gravity and make her very stiff.
There is a variety of ways in which a ship can be damaged by high-density cargoes when badly distributed, and the following errors must be avoided: individual holds must not be overloaded; unsuitable block loading must not be used; excessive shear forces and bending moments must be avoided .
There is a number of operational reasons why it is more efficient to carry heavy cargoes such as iron ore only in alternate holds, a system known informally as 'jump loading', and for this reason many bulk carrier have been classified as 'strengthened for heavy cargoes, (alternate) holds may be left empty'. When so classed, it is permissible to load a full deadweight cargo, using only alternate holds, normally the odd numbered ones.
required when iron ore cargoes are being carried, but three normal precautions can be emphasised. Bilges should be pumped regularly to dispose of water draining from the cargo. Bilges should be sounded regularly to detect any sign that the vessel is leaking and a hold is flooding. Holds should not be entered except when the air has been found to be safe.
Iron ores are self draining. Iron ore loaded in Port Cartier, for example, may in summer be shipped with an average moisture content as high as 5 per cent43, but excess water will drain to the bottom of the hold with about 2.5 per cent being retained in the cargo. Excess water remaining in the hold is likely to cause inconvenience during discharge, so bilges should be regularly pumped dry during the voyage.
To avoid disputes in which cargo shortage is alleged after large tonnages of water have been pumped overboard,
the ship should keep a record of the tonnages of bilge water discharged. These tonnages can be calculated when the ship has bilge calibrations by recording the bilge soundings before and after pumping bilges.
Alternatively, bilges can be pumped to a calibrated tank and sounded therein before discharge.
A number of bulk carriers have foundered when carrying cargoes of iron ore. The foundering may
have been preceded by flooding of holds. Hold bilges should be sounded daily to detect flooding. Flooding will be distinguishable from drainage of water from the cargo by the fact that the increase in sounding will be limited to one or two holds and that it will be more rapid.
Iron ores are liable to oxidise, thus reducing the oxygen in the air. The atmosphere in the hold must be tested to ensure that it is safe before the hold is entered or compressed air breathing apparatus must be worn. There is no requirement to ventilate iron ore cargoes, and practices vary. Some masters keep ventilators closed to exclude rain and spray from the holds. Others ventilate to maintain a healthy atmosphere within the hold.
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