The cargo is a lead residue resulting from a metal recovery process that extracts zinc from a specifically manufactured ore or concentrate.
Cargo properties
Leach residue is usually extremely fine and may contain traces of lead and sulphuric acid from the extraction process. The particles will have strong suction characteristics and retain moisture until exposed to stress from loading and/or vessel motions.
Cargo hazards
The cargo is listed in the IMSBC Code as a ‘material hazardous in bulk’ (MHB); being both corrosive and toxic. Cargoes that are listed as MHB are those that have hazards not found in the IMDG code (hazardous goods in packaged form) and are only hazardous in bulk form.
Therefore, the cargo schedule is not given a UN number as per IMDG code cargoes as per section 4.1.1.3 of the IMSBC code.
The residue is also very fine, therefore posing a liquefaction hazard. As such the cargo is listed as both GROUP A and B.
Importantly, it should be noted that there is also a hazard to humans. The cargo is corrosive to the eyes and is known to potentially cause long term health effects
Control measures generally concern avoiding generating dust, avoiding contact or inhalation, and keeping away from naked flames and heat sources. Measure the concentration in air regularly and undertake cargo operations in the open/under local exhaust / ventilation or with respiratory protection.
The Code advises that the cargo can give off toxic gas when heated strongly (higher than 1,000°C).