20 
The CLB system was successfully tested in 8,650 meters of water 
north of Tahiti in August 1970.11 A later test in August and Sep- 
tember 1972 recovered seven tons of nodules off Hawaii.” Several 
participants of the CLB consortium under the leadership of CNEXO 
of France are developing a modification of the CLB which involves 
the use of two ships working in tandem."? Members of the CLB Group 
met in Houston in May 1974 to plan financing and construction of 
a two-ship system which is expected to be ready for tests in late 1975. 
The system will be built in France by Ateliers et Chantiers de 
Bretagne.** 
The primary advantage of the CLB system over the other two tech- 
niques is simplicity and perhaps cost. The latter advantage has been 
strenuously disputed.?® It also has the advantage of being able to 
recover nodules of any size and does not need to be designed for a 
specific depth and type of sediment as do hydraulic and air-lift sys- 
tems. Dfficulties with the CLB system may result from irregular bot- 
tom topography and potential snags. The buckets must also pick up 
a good load of nodules and little sediment for the system to be eco- 
nomic, and there is no way to control how the buckets interact with the 
bottom. Critics also claim the system cannot be cycled rapidly enough 
to recover a profitable tonnage of nodules." 
Mining efficiency of this system again can only be estimated. The 
area mined is controlled by maneuvering the surface mining ship or 
ships; consequently, bottom coverage and nodule recovery may be 
somewhat inefficient. 
Nopute Processtine 'TrcHNoLoGY 
Because of the mineralogy of ferromanganese nodules is unlike that 
of any commercially mined land-based mineral deposit, straight- 
forward methods of extracting metals do not work. The manganese 
oxide and iron oxide minerals that are the main constituents of the 
nodules are extremely fine-grained and are bound in a rock (siliceous) 
matrix. Most of the other metals of interest are present in the nodules 
essentially as impurities in the iron and manganese oxides. Conse- 
quently, physical methods of separating the metals have not proved 
successful. Although it is possible to reduce the oxides by smelting, 
the resultant alloy of iron and other metals is difficult to separate 
further. Generally, chemical leaching or hydrometallurgical tech- 
niques are considered the most likely commercial methods. Details of 
most of these methods are regarded as proprietary information by the 
companies developing them. From information available, general 
descriptions of some of these extraction methods or metal winning 
processes can be derived. 
4 Masuda, Y., M. J. Cruickshank, and J. L. Mero. Continuous bucketline dredging at 
12,000 feet. Offshore Technology Conference, Preprints Paper No. 1410, 1971. mae 
“ Mining Magazine, January 1973, p. 7. 
18 United Nations, A/CONF.62/25, op. cit., p. 19. 
a yee naeto AAO EL No. 61, January 1974, p. 5. 
5 ond, A. L., Maganese Nodules (II) : ini y 
183, Feb. 15, 1974, oo. ea (II) : Prospects for Deep Sea Mining, Science, v. 
16 Thid., p. 644. 
