39 
nodules per year. Consequently, a mining company may be expected 
to operate 2 or 3 mining rigs and a plant designed to process 3 to 4 
million tons per year. However, Deepsea Ventures, which intends to 
roduce metallic manganese for which the world market is small, 
initially plans a plant of only about 1 million tons of nodules per 
year. 
METAL PRODUCTION PER TON OF NODULES 
Processing techniques and grade of the nodules will determine the 
metal production per ton of nodules which effects the economic impact. 
Industry sources have generally indicated that the minimum metal 
enrichment for a nodule deposit to be economically profitable is on 
the order of 2 to 2.5 percent combined copper and nickel. High cobalt 
values could lower the acceptable copper plus nickel grade if a com- 
pany were more interested in marketing cobalt. The amount of metal 
recovered depends on the efficiency of the metallurgical process de- 
veloped. Indications at present are that industry may obtain yields 
on the order of 90 to 95 percent of the major metals from the nodules. 
Trace metals such as molybdenum, vanadium, zinc, silver, the platinum 
group, etc., may be recovered at slightly lower yields on the order 
of 80 percent. Table 5 is a projection by the United Nations for metal 
production per million tons of nodules. These projections assume an 
average metal content that may be somewhat higher than a typical 
commercial grade deposit would assay. From public comments of in- 
dustry spokesmen, commercial deposits may average 25 percent man- 
ganese, 1.2 percent nickel, 1 percent copper, and 0.2 percent cobalt. An 
average metallurgical recovery efficiency of 90 percent may also be 
more likely initially. Using these figures a one million ton per year 
operation might be expected to produce 225,000 tons of manganese, 
10,800 tons of nickel, 9,000 tons copper, and 1,800 tons cobalt. In terms 
of 1973 U.S. imports, a one million ton per year plant (the minimum 
size likely) could provide approximately 6 percent of nickel imports, 
2.5 percent of copper imports, and 19 percent of cobalt imports, Com- 
parisons of nodule production to manganese imports are generally mis- 
leading because most manganese imports are not converted to the 
higher value pure metal which would be the product of nodule 
processing. 
TABLE 5.—ESTIMATED METAL PRODUCTION PER MILLION TONS OF HIGH GRADE NODULES (METRIC TONS) 
Metal content Approximate metal 
per weight of production per mil- 
dry nodules lion tons of dry 
Metal (in percent) nodules (in tons) ! 
NManzaneser(imecovencd)cassseee een 6 ee snes eee 24.0 230, 000 
Icke tet Ae oy) eeeer aay Baye cipeed bere: dor os pei 1.6 15, 000 
Cop Ras= ees ee ee ee eee ee es eee 1.4 13, 000 
Gobaltes_ 2. Se Ree SOOPER aE OEE: Fe ER EUR Se SAAD Shit, ASTER ed 574i 2, 000 
Othemmetalseeeors ssc = See ee ee SR a eas ot 43 2, 500 
1 Assuming 95 percent metallurgical recovery except for trace metals where an 80 percent rate is assumed. 
Source: Ibid., p. 28. 
_ Another estimate of metal recovery from nodules by U.S. mining 
interests in 1985 was prepared by Robert Nathan Associates for the 
Senate Committee on Commerce, National Ocean Policy Study 
