This paper presents the concept of an integrated mining system based on self-propelled, track pad mounted crawlers equipped each with a collector, a crusher and a pumping unit, an umbilical consisting of a flexible hose and a cable with associated buoyancy packages, a mother station with the needed utility systems (electricity), support systems (propulsion. position control, slurry handling and crawler handling) and control systems (transducers, actuators, computer communication, video surveillance).
To understand the concept of the flexible riser mining system and its advantages, it is helpful to look back at the mining concepts developed in the past and their drawbacks. The most elaborated and advanced concept of the 70ies consisted of a drilling ship, an approximately 5000 m vertical steel pipe and a towed collector. After various theoretical analysis (e.g. Kohne, 1974, Kohne 1976, Chung 1981) this system was realised by a group of companies under the name of Ocean Management Incorporated (OMI), and is shown schematically in fig. 1. The considered output was 3 million tons of wet nodules per year. IKS, amongst various other research institutes and companies, developed from the eighties on a system, which is expected to minimise the problems listed above, except for the legal aspects on which the design can have no influence. This development resulted in what we call today the flexible riser concept with self-propelled mining machines feeding a mother station, as shown in Fig. 1. Unlike a mining system developed by Ocean Minerals Company (OMCO) and tested by Lockheed Martin (Welling, 1996), where the miner delivers the nodules into a buffer through a flexible riser, to pump it to the surface through a rigid pipe string, the concept developed by IKS uses a flexible riser from the mining machine to the surface of the sea.