18 
traversing the mine site the mine ship can accomplish. From a resource 
management point of view, it would be desirable for the site to be 
mined as efficiently as possible to minimize the area of disturbance. 
From a reliability point of view, although the ALP system must 
supply great amounts of compressed air to various water depths, there 
are no underwater pumps and other machinery to break down. How- 
ever, the ALP system is more complex in concept than a CLB system 
which doesn’t have a long pipe string to handle, and the bucket system 
is more flexible in the ability to cope with a variety of bottom 
conditions. 
HYDRAULIC LIFT 
The hydraulic or hydrolift system is similar to the ALP, but it 
relies entirely on pumped water to provide upward flow through the 
pipe. This is technically a two-phase system: nodules and water. The 
technology for this system is already well developed and is used in 
the coal industry and in mud pumps used in oil drilling. The pump 
can be located close to the bottom or at intermediate depth. The 
hydraulic system seems to be favored by a recently formed interna- 
tional consortium managed by Kennecott Copper Corp.® ® 
MECHANICAL LIFT 
The third major recovery method, the continuous line bucket (CLB) 
system, appears to be the simplest in principle. This system uses a 
continuous polypropelene braided rope with dredge buckets attached 
at 25 to 50 meter intervals. The rope is wound through traction motors 
mounted at both forward and aft ends of the mining vessel. Because 
the rope line is neutrally bouyant, it tends to loop out away from the 
direction of motion of the mining ship (Fig. 10). As the line rotates 
the bottom of the loop drags across the seabed filling the buckets. The - 
drag and increased weight of the buckets causes the loop to become 
more directly aligned with the lifting force. Consequently, the line 
moves upward more nearly vertically than its descent, and fouling of 
the loop upon itself is avoided. 
8 Tinsley, C. R. In search for commercial nodules, odds look best in, Miocene-age Pacific 
l 6. 
Tertiary System. Engineering and Mining Journal, June 1973, p. 114-11 
9 Oceanography Newsletter, v. 9, No. 3, Feb. 1974, pp. 1—2. 
