Study of the CLB Mining System for Nodule Crust Recovery

摘要

The Continuous Line Bucket(CLB) is a mechanical system using an endless loop of rope suspended from a surface platform to reach the seabed and to which dredge buckets are attached at regular intervals.rnThe Turning CLB is a recent important innovation; by steering the vessel in a circular track.trailing the empty buckets over the stern and bringing up the loaded buckets amidships from whithin the arc of the ship's track.a good separation of lines has been acheived.rnImprovements to the CLB components which have been tested recently include: horizontal traction wheels and ball rollers used in combination to decrease the number of traction wheels by half: new bucket guides and dumping device to automate discharge of the loaded buckets without removing them from the line: and snall model test for bucket guides was done. double braided polyesterylon rope adopted to increase the life of the rope; and various bucket configurations including a piano wire mesh bucket designed by the French Group IFREMER. Filling efficiencies of over 60% were recorded for the buckets.rnThe CLB system was evaluated for nodule deposits in 5,000 m water depth, for three sizes of ship (15.000 t. 30.000 t and 60,000 t), and three production rates (500t/d. 1.OOOt/d and 2.000t/d).rnUsing buckets of 0.75 m~3 capacity with line intervals of 50 m, 25 m and 12.5 a, the forces required for the ascending line were estimated to be 46t for 500 t/d. 92.4 t for 1.000 t/d.amd 184.8 t for 2.000 t/d.rnTraction power required at 0.8 m/s line speed was estimated to be 500 KW for 500 t/d. 1.000 KW for 1,000 t/d. 2.000 KW for 2.000 t/d.rnRope sizes selected for the evaluation were 110 mm for 500 t/d. 150 mm for 1.000 t/d and 210 mm for 2.000 t/d.rnTwo 8 ton ball rollers and 6 traction wheels for the traction device were estimated to cost about 6 million dollars for the case of 1,000 t/d.rnRope and buckets were costed as consumables. With a rope life of 1-1.5 years,unit production cost was estimated at $109/t for 500 t/d.$76.7/t for 1.000 t/d,and $ 54.1/t for 2,000 t/d in 1994 study.rnThe CLB was evaluated for crust nining on the 5th Takuyou Sea Mount(l,400 m) by the Crust Study Commi-ttee of Japan Resources Association. Additional evaluations have been made in the Republic of the Marshall Islands.rnThe CLB is a potential crust mining method where fragmented crust deposits are found.