3.2 Design and Development of Test Deep Seabed Mining System


As a first step towards developing the various components of the deep seabed mining technology, a study was commissioned to delineate the design concepts of various mining systems. The Central Mechanical Engineering Research Institute, Durgapur was identified as the main centre for research and development work in seabed mining technology with support and participation of public and private sector organisations like Bharat Earth Movers. Limited, Bharat Heavy Electricals Limited, Institutes of Technology, etc. The first phase of the programme is aimed at developing a land based- cum-shallow basin prototype of a remotely operated underwater nodule collector together with a lifting system. The nodule collector is expected to be first tested on land for its performance and remote operational capabilities. The lifting system will also be tested on an experimental test setup. The performance of the combined system will be evaluated in a shallow basin.

The test system designed by CMERI, Durgapur consists of the following subsystems:

A remotely controlled active collector with technical and hydraulic collecting head for gathering nodules. The screening and crushing of nodules will take place in the collector unit.

The bucket-in-pipe lifting system for vertical transportation of the nodules. This system consists of a vertical U-pipe, buckets fitted on rope-line and drive system for the rope .

Robotic manipulator to assemble/ disassemble the flexible pipe connecting the collector to the lifting system. This is needed for maintenance/deployment/ retrieval of the collector without disturbing the lifting system.

Remote control system of the collector unit, with the aid of a hydraulic circuit and electrical and fibre optic communication system and creation of a shallow-basin test facility.

3.2.1 Collector Unit

The primary task of the collector unit is to collect the nodules with scooping-type and hydraulic jet-type collecting head. The nodules will be transported through a bucket elevator to the screen for screening and then crushed in a roller crusher. The nodules are then fed to the riser section for vertical transportation by means of a slurry pump through a flexible pipe. The collecting head is mounted on the crawler vehicle for the desired movement.

The crawler vehicle has been fabricated already and a trial runs for remote operation have been made. The collector unit is under fabrication.

3.2.2 Bucket-in-pipe Lifting System

Based on the conceptual design of the bucket-in-pipe riser system, a scaled-down model for approximately 1 m lift was designed for detailed experimental analysis. Its fabrication ha-5 been completed and the test plan finalised. After necessary parametric study at the laboratory, the system will be shifted and integrated with the collector module at the shallow basin facility presently under construction, for testing the combined system.

3.2.3 Robotic Manipulator

In order to assemble/disassemble the flexible pipe extending from the collector unit to the riser section, it is required to employ a typical robotic manipulator. R&D effort has been directed to design and develop a gripper and holding system for the flexible pipe which can be connected disconnected during operation, as needed for maintenance/deployment/ retrieval. A laboratory scale set up is under development for testing. Orders for the procurement of a manipulator have been placed.

3.2.4 Remote Control System

The remote control land instrumentation systems for the deep sea mining project envisage remote operation of the vehicle and the data acquisition relating to the speed, obstructions, tilt, heading angle, positions, etc. of the collector unit mounted on the vehicle. Necessary system design and implementation scheme have been worked out and steps have been taken to test the crawler vehicle for land and shallow basin operation. Parallel to this development, a fibre optic communication system has also been undertaken to reduce the number of cables and the use of the repeater stations for video signal transmission over a length of 2.4 km without distortion.

Work on underwater motor development and power transmission to the prime movers is under way for the next phase of the project.

3.2.5 Shallow Basin Test Facility

To test the performance of the combined mining system underwater, a shallow-basin test facility has been designed and construction is nearing completion. The test facility is fully equipped with a control room, underwater lighting system for or photography, dry-dock arrangement and riser structure.