22 
Fig.11 Hydrochloric acid process 
Wet nodules 
Countercurrent leaching 
Ferric chloride removal = disposal Fuel 
(5 stages) 
=| 
FeCl, : 
use decomposition a 
ae makeup 
Mn H20 Al 
! 
Mn crystallizer Mn metal 
Steam 
Copper recovery Al203 
BG Copper 
electrowinning 
Nickel recovery 
Bg 5 By Nickel 
electrowinning 
Cobalt 
Source: Sisselman, R. Ocean Miners take soundings on Legal Problems, Development 
Alternatives, Hngineering and Mining Journal, April 1975, p. 86. Copyright 1975, Engi- 
neering and Mining Journal, 1221 Avenue of the Americas, New York, N.Y. 10020. 
A proprietary ion exchange process extracts each metal into a sepa- 
rate solution from which it is plated out in an electrolytic cell. Since 
manganese cannot be recovered electrolytically, another proprietary 
method is used for this metal. : 
The metals initially slated for recovery by this method are cobalt, 
copper, nickel, and manganese. Recovery of other metals such as mo- 
lybdenum, vanadium, zinc, and cadmium is being considered should 
market conditions make their production profitable. This apparently is 
the only process being considered commercially that would produce 
high-purity manganese from the nodules. 
Advantages of this method are the high recovery rate of the metal 
content of the ore (better than 95 percent) and the low potential for 
pollution problems (the solvents are recycled). 
SULFUR DIOXIDE ROASTING AND WATER LEACHING 
A second process, suitable for production of manganese in the form 
of ferromanganese, is the sulfur dioxide (SO:) roasting method devel- 
oped by the U.S. Bureau of Mines. The basis of this method is to get 
the ore in the form of soluble sulfates by roasting in an atmosphere of 
SO, and air, followed by leaching in water. Copper is precipitated out 
directly using metallic iron, while nickel and cobalt are recovered by 
an autoclaving technique. Further purification of the nickel and cobalt 
