Low rank (geologically immature) coal, such as that loaded off Kalimantan, is susceptible to self-heating if loaded at a temperature of over 55°C. In the past two years, consulting engineers J H Burgoyne and Partners have dealt with 23 such cases, 10 of which have taken place in the last year months, showing great concern.
Coal awaiting shipment is often stored in barges close to the anchorage areas where it may be exposed to strong winds and rain. Such conditions may promote self-heating, and barges containing coal with a temperature exceeding 55°C have sometimes been encountered.
However, not all operators appear to be aware of the risks and some vessels have
only identified the problems after the cargo has been loaded. Once on board it is
not easy to remove the coal due to the lack of discharging facilities in the region.
The link below leads to the original article, where you can read in full the requirements and regulations to ensure that this problem is prevented.
A PDF version of the article can be downloaded here