3. Deep Seabed Polymetallic Nodules
India as a registered pioneer investor has been allotted an area of 1,50,000 sq.km. (mine site) in the Central Indian Ocean basin for exclusive exploration and development. An action plan has been drawn up for the implementation of deep seabed polymetallic nodules programme, which covers three main thrust areas viz:
(i) Survey & Exploration;
(ii) Development of a mining system; and
(iii) Extractive Metallurgy.
3.1 Survey and Exploration
India was the first country in the world to get pioneer investor status in August 1987 on the basis of delineation of a prospective area covering 3,00,000 sq.km. The survey and exploration efforts till now have been directed mainly to assess the relative concentration and quality characteristics of nodules and broad seabed topography. The sampling grid has been progressively reduced from 100 km. to 25 km. and later to 12.5 km. to get more accurate information on nodules abundance. The survey for mapping and detailed bathymetry of the pioneer area has been subsequently strengthened by the use of a multi-beam swath bathymetric system(Hydrosweep) on ORV Sagar Kanya. The Survey of the entire Pioneer area of 150,000 sq.km. has been completed by using the Hydrosweep. About 70,000 line km. gravity data, 2,65,000 km, magnetic data has been collected. Environmental data, baseline oceanographic data on physical, chemical and biological parameters has also been collected. High resolution bathymetric maps of the pioneer area covered during the research cruises have been prepared which give the detailed topography of the area enabling the identification of sea mounts and slopes which cannot be negotiated by mining equipment.
3.2 Design and Development of a Test Deep Seabed Mining System
The work on design and development of a mining system was entrusted to the Central Mechanical Engineering Research Institute (CMERI), Durgapur, in 1989-90.
The first phase of the project has been completed. As a part of the implementation of the first phase a remotely operated collector unit and a bucket-in-pipe lifting system have been commissioned and the system tested in a shallow basin of 4.5 metre depth specially constructed for the purpose. A master slave manipulator has also been commissioned.
The test mining system designed by CMERI consists of four major sub-systems viz.(i) collector unit, (ii) bucket-in-pipe nodule lifting system, (iii) robotic manipulator for operation and (iv) shallow basin. The details of the work done during 1992-93,are as follows :
The first generation collector module has been commissioned and extensively tested for its functional performance on hard soil as well as on marshy land from a distance of about 500 mt. Tests have also been conducted in a shallow basin of 4.5 mt. depth. In the collector unit a pick uf) system has been employed. Data has been generated and analysed by CMERI. Each vehicle track is operated independently by hydraulic drive and motors controlled through a PLC via cable link.
The fibre optic data link has been designed and installed. Proximity sensors, pressure transducers, etc. are used as appropriate in remote control of the vehicle from a distance of about 500 mt. The problems likely to be encountered in sea trials have been identified.
Bucket-in-pipe Nodule lifting system
A 100 tonnes per day capacity bucket-in-pipe nodule lifting system has been designed and commissioned and tested to verify design parameters and to generate data base for further improvements in the system. A preliminary system arrangement for assembling and erection of riser system on board the mining ship has been worked out. The lifting system has been installed at shallow basin for testing along with the collector module.
Robotic Manipulator for Tele Operation
A remotely operated master slave manipulator to test and to remove the collector unit from the rest of the mining system for eventual repair and maintenance has been acquired from Canada and installed at the Central Mechanical Engineering Research Institute. The unit has been integrated with the collector vehicle for primary tests and compatability and initial trial runs completed. The design work of the indigenous manipulator also has been taken up as a part of the next phase of work
Shallow Basin Test Facility
A shallow basin (50m. x 10m. x.4.5 m) test facility has been designed and construction completed. The test facilities like underwater lighting system for photography, dry dock arrangement and riser structure have also been completed. Test run of collector and riser module is being carried out at shallow basin and data is being generated.
In the phase II of the project improvements in the design and development of the system with a view to ultimately finalising the working model at shallow depths of 200 metre will be carried out. Work on the design of a sea-going collector unit, studies on hydraulic and airlift system, development of a Remotely Operated Vehicle(ROV) for pipeline inspection, water- proofing of electrical and hydraulic components for underwater use, development of hydraulic nodule pick-up system, development of electric power transmission to underwater system, development of instrumentation and control for seagoing collector unit, pipe deflection analysis and measurement system, manipulator development and investigation of seabed properties etc. have been initiated.
Intermediate Use of Technologies
Development of high technologies has correspondingly higher innovative potential with widespread spin-offs that progressively extend the opportunity base for many national activities that have to be performed in difficult environmental conditions. The technology being developed for the nodule collector unit, hydraulic and air lift systems, remotely operated vehicles, water proofing of electrical and hydraulic components and electric power transmission equipment etc. has potential for use by organisations like IOC, ONGC, N PC and GSI in the exploration of EEZ resources.
The technology developed for exploration and extractive metallurgy will be relevant for ;
3.3 Extractive Metallurgy
Fifteen process routes for extraction of metals from nodules were initially selected for investigation of which three routes were choosen for upscaling.
A process following the reduction roast ammonia leach route was developed at the National Metallurgical Laboratory, Jamshedpur on bench scale, scaled upto 100 kg. of nodules per day and a pilot plant commissioned. Three pilot plant campaigns for obtaining energy and material balance have been completed during the year at this pilot plant.
The ammonia sulphurdioxide leach route was developed at the Regional Research Laboratory, Bhubaneswar and a pilot plant of 150 kg. nodules capacity per day was established. Three campaigns have been completed during the year at the pilot plant and data gaps and problem areas have been identified. The additional campaigns and experiments required in areas such as reduction roasting, continuous leaching, improvement in cobalt recovery, application of different reagents for metal separation, production of cobalt/metal from cobalt chloride crystals, automation in solvent extraction-electrowinning have been identified for future improvements and firming up of the design parameters of a semi-commercial plant.
3.4 Placer Deposits
.An expert group has been constituted to evaluate the proven resources of placer deposits in the near shore and EEZ area and their economic exploitation and make recommendations with regard to their exploitation, the environmental implications, and suggest organisational structures and modalities for the same.
3.5 Board of Management
The Board of Management for the Polymetallic Nodules programme reviewed the progress of the programme. The Board discussed in depth the matters concerning fulfilment of obligations by India as a Registered Pioneer Investor, future plan of action with regard to exploration, completion of bathymetric maps, fine scale visualisation of seabed nodule distribution in the pioneer area, development of a test mining system and work plan for metallurgy pilot plant campaign operations.
The Board constituted three sub- committees to review all aspects of the work of the programme being carried out by different laboratories. The Committees would suggest directional changes, if any, required for the implementation by the programme and also the need for funds for the programme.