Studies on the dry chlorination of deep sea manganese nodules
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Authors' Reply BAHRI OZTURK, P. BARRON, and R. J. FRUEHAN The points raised by Seetharaman and Staffansson concerning the Gibbs free energy formation of stannic oxide (SnO2) are well taken. The purpose of our investigat!on was to determine the activities in the lead tin system at 600 K. The H J H 2 0 ratio in equilibrium with pure tin and lead-tin alloys was determined using a gas equilibration technique. In this technique, when the Hz/H20 ratio is just below or above equilibrium the rate of SnOz formation or reduction is very slow. Therefore the equilibrium value can be bracketed accurately up to a certain interval. The errors corresponding to these intervals are given in Figure 5 of Reference 1. The Gibbs free energy of formation of SnOz is obtained from the H//H20 ratio that is in equilibrium with pure tin at only 600 K. The value of AG~no2 obtained in this study is in agreement with previous investigations, as reported in the paper, within experimental uncertainties. On the other hand, activities in the Sn-Pb system were obtained using the [Hz/H20]alloy/[Hz/H20]pureS n ratio and are expected to be more accurate.
REFERENCE 1. B. Ozturk, P. Barron, and R.J. Fruehan: Metall. Trans. B, 1987, vol. 18B, pp. 577-82.
Studies on the Dry Chlorination of Deep Sea Manganese Nodules B. V. R. MURTHY, B. R. REDDY, G.N. SRINIVASAN, D. N. DEY, and P. K. JENA Studies were conducted on the chlorination of manganese nodules obtained from the Indian Ocean using dry chlorine gas for the extraction of metal values like copper, nickel, cobalt, and manganese. Experiments were carried out in an electrically heated silica tube furnace to study the effect of various process parameters such as temperature, retention time, percentage addition of wood charcoal, chlorine gas flow rate, and particle size of nodule and the charcoal. Successful attempts were made to preferentially extract copper, nickel, cobalt, and manganese metal values by appropriately controlling the experimental conditions. In a B. V.R. MURTHY, B.R. REDDY, and G.N. SR1NIVASAN, Scientists, D. N. DEY, Assistant Director, and P. K. JENA, Director, are with Regional Research Laboratory, Bhubaneswar-751013, India. Manuscript submitted October 31, 1986. 514--VOLUME 19B, JUNE 1988
typical run, it has been possible to bring 85 pct copper, 90.6 pct nickel, 94.0 pct cobalt, 85.7 pct manganese, and 0.6 pct iron to a water soluble state. Leaching studies conducted on the roasted chlorinated product indicated that about 90 pct metal values could be recovered while leaching even at a pulp density of 35 pct at 30 ~ for a period of only 15 minutes. The steady depletion of land-based mineral resources of some strategically important base metals such as copper, nickel, and cobalt has necessitated the search for alternative sources for these metals. In recent times deep sea polymetallic nodules have attracted global attention in this direction because of their rich content of the above metals and abundant availability of manganese in the nodules.r~l Extensive efforts are being made through
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