ABSTRACT:

A tracked under water mining system with a polymetallic nodule collector, crusher and positive displacement pump has been developed and tested at 500 m water depth. This system is a continuation of the developmental work done using flexible riser concept for mining fine seafloor materials like sand and silt in 2006. The collector device of the machine has three modules of mechanical pick up devices and cleated belt conveyors. The collected nodules are fed in to two crushers for size reduction and lateral transport. The crushed nodules are then pumped to the mother vessel by a twin cylinder positive displacement pump through a flexible riser. The system was tested near Angria Bank off Malvan coast in Arabian Sea at 512 m depth during October 2010. This paper describes in detail the various systems and devices in the mining machine and the results of the mining tests carried out at the site.

INTRODUCTION

Integrated Mining System proposed for mining polymetallic nodules from the deep ocean floor in Central Indian Ocean Basin (CIOB) is based on Flexible Riser Concept and multiple mining machines (Grebe et al, 1996). The mining system will consist of three to four crawler based underwater mining machines connected to a single small floating semisubmersible platform (Handschuh et al, 2001) as shown in Fig. 1. The mining machine has polymetallic nodule collector with mechanical pick up devices, cleated belt conveyor, crushing system and solid-water transportation system with a single positive displacement pump. The polymetallic nodule mining system has been proposed to be developed in four phases. The flexible riser concept was tested during 1998–2000 (Deepak et al, 2001). Demonstration of the concept for long term operations required dynamic positioning in the mother ship Sagar Kanya for launching and recovery operations.

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