More than 40 years ago TAKRAF supplied the first F60 conveyor bridges. In order to ensure operational reliability and stability for a further long-term use of the conveyor bridges, the company says it has now developed several modernisation and refurbishment schemes. On the basis of comprehensive structural analyses made during recent years, TAKRAF proposes to replace the large equaliser, roller table, ball and socket joint of Ø 1,250 mm and vertical rail of the 60 m/33 overburden conveyor bridge. Another aspect of the proposed modernization program is the replacement of the tie rod heads.
The systematical refurbishment of load bearing areas is part of a comprehensive program to increase machine safety for the conveying bridges. The program is developed on the basis of a close cooperation of equipment operator, equipment supplier and governmental mining supervision authorities. The most challenging issue in this program is to divert the enormous supporting forces of the 3,200 t of the large equaliser and of 2 x 2,100 t of the tie rod heads in such a way that it will be possible to replace the parts.
The replacement of the large equaliser and the roller table is planned as follows: the overburden conveyor bridge will be positioned according to the technological requirements at the time planned for the complex repair in such a way that the main bridge on the excavator side is lifted by means of the temporary auxiliary construction (support of bridge cross conveyors, shifting and attaching devices for large equaliser and roller table, auxiliary structure) in order to dismantle the roller table and large equalizer with ball and socket joint of Ø 1,250 mm.
The replacement technology not only includes the manufacturing dimensions of the large equaliser and the roller table and the transport roadway from the Lauchhammer factory to the respective mine site, but also the requirements for the installation on site and the transport route in the opencast mine. For the replacement of the tie rod heads TAKRAF has planned a program that the downtime of the conveyor bridge will be in the range of approximately 10 weeks only. The fabrication of the tie rod heads and the load relieving structure will be prefabricated in the Lauchhammer workshop. To achieve the anticipated 10 weeks downtime the onsite works will be performed in a three shift working scheme, during which time period the dismantling and reinstallation will take place.