ALCOHOL-MODIFIED HYDROCHLORIC-ACID LEACHING OF SEA NODULES

The effects of propanol and butanol additions in dilute hydrochloric a cid leaching of Cu, Fe, Mn, Ni and Co from sea nodules from the Indian Ocean were investigated. In the absence of any additive, dilute hydro chloric acid (2.75 M) in aqueous medium leaches only 80% copper and 60 % iron. More than 90% recovery of all the metals is achieved only when highly concentrated acid (11 M) is used. It has been found that metal recoveries can be considerably improved even in 2.75 M HCl solution i f an appropriate amount of propanol or butanol is incorporated, Additi on of only 9 vol% propanol or 4.5 vol% butanol is sufficient for achie ving about 90% recovery of each of the metals. It has been further obs erved that the amount of alcohol required for the satisfactory recover y of metals decreases with the use of longer chain length alcohols. Th e effects of other parameters, such as the period of leaching and acid concentration, on the recovery of metals was also studied.