Spillage measurements during grab unloading

During the handling of bulk solid materials, some material is spilled e.g. due to leakage from a grab. This material may build up at the vessel's deck, at the quay or it may end up in the water or in the air, and can be harmful for the environment. In Europe the regulations and legislation on environmental control is getting very strict. In the Netherlands this has resulted in discussions between Ministry of Transport, Public Works and Water Management and the stevedores to what extent measurements to prevent spillage should be taken. The objective of this research was to determine the amount of spillage that occurs during grab unloading and enters the surface water. In literature hardly any figures are available on the amount of spillage that occurs during unloading with grabs. Therefore it is necessary to collect experimental data in order to quantify the spillage. Here, both the developed spillage measuring method as well as the obtained measurement results of the amount of spillage during grab unloading, are presented. To be able to compare the results of the measurements the so called spillage number is introduced. The results show a difference in the amount of spillage between floating cranes and portal cranes.