Delft University of Technology
Faculty Mechanical, Maritime and Materials Engineering
Transport Technology

P.A. van Gaelen en N. Kuijken Meten van mors bij de overslag van stortgoed - deel II
Experiment, Report 2007.TEL.7186, Transport Engineering and Logistics.


Recently more and more attention is asked for the protection of the environment. As a big polluter, the stevedore industry also has to live up to stricter regulations, concerning the loss of coal during transshipment and substance - and noise nuisance.
Due to obscurity concerning the new regulations and the lack of reliable numbers about the degree of coal lost during transshipment, Delft University of Technology started a project together with 12 bulk handling corporations, Rijkswaterstaat, NIEMA, Syntens and the Erasmus University Rotterdam. This experimental study is the third paper in this cooperation.
The aim of this research is to quantify the amount of coal lost in the surface water during transshipment. Besides this the paper focuses on the differences of the particle size distribution of the coal loaded and the distribution of coal that is spilled.
In the period from august 2007 till September 2007, 13 measurements have been carried out at 5 cooperating stevedores. To get a good understanding of the loss of coal during transshipment a logical combination of stevedores and crane types is chosen.


During a measurement it is strived for to measure for 2-3 hours during constant circumstances at full ships' holds. Depending on the situation and the trajectory the gripper of the crane made, areas were outlined on the ship, the pontoon, the quay and/or the barge. After a certain period of time, in which the number of cycles of the gripper is registered, the mass of the coal spilled on the outlined area's is measured. The measured mass of the spilled coal is divided by the area of the outlined area and the total mass of coal that passed over this area during the transshipment. This gives a specific number expressed in kg/(m2.kton). This number is called the GaKu. The GaKu of the different areas are plotted and the GaKu above the surface water is interpolated. By multiplying the GaKu above the surface water with the area of the surface water and with the total mass of transshipped coal, the mass of the coal that is spilled in the water becomes known. With the same method the total mass of coal spilled per year is calculated.
During the measurements the factors that have influence on the spilled are registered. These factors are wind power and wind direction, the experience of the crane operator, the filling degree of the gripper and the ship's hold, the construction of the cranes, damage and delays.


From the data of the thirteen measurements the following conclusions can be formulated. Because of the large number of factors that influence the spillage of coal, the fact that the data comes from several sources and that some assumptions have been made, the reliability of the measurement and calculations has been examined. The reliability of the calculations at portal cranes is around 14%. For floating cranes this is around 16%. The main reason for this difference is that, for floating cranes, the trajectory of the gripper from the ship's hole to the barge or quay wall can't be determined precisely. With the reliability of the calculations between 14% and 16% there can be concluded that the reliability and punctuality of the stated mass of spilled coal is admissible.

In addition to the mass of the spilled coal, the relation of the particle size of the loaded coal and the spilled coal is examined. At five measurements the particle size distribution is determined with the help of a sieve analysis. Based on the results the following can be concluded. All three these conclusions became clear from the available data. Further research must lead to a more elaborated substantiating.


Due to the experiences of this research recommendations for following researches have been formulated.

Reports on Transport Engineering and Logistics (in Dutch)
Modified: 2008.01.26; , TU Delft / 3mE / TT / LT.