Ocean Nodules Research Articles

Kinetics and mechanism of the reductive ammonia leaching of ocean nodules by manganous ion

The kinetics of reductive ammonia leaching of ocean nodules by manganous ion were found to be chemically controlled. The rates of Cu, Ni and Co extraction all show an order of dependence of 0.5 each on total ammonia and manganous ion. The logarithm of metal ion extraction rates vs. pH shows a maximum at about pH 9.0 to 9.5. The orders with respect to [H +] are −0.5 and 0.5, respectively, in the pH ranges of 7.0 to 9.0 and 9.5 to 11.0, due to various protolytic equilibria involving ammonia and Mn(II). The rates of metal ion extraction have the order Cu > Ni > Co. A chemical surface-leaching reaction mechanism is proposed, involving adsorption of manganous ammine on the nodule lattice, thereby liberating Cu, Ni and Co minerals, which are subsequently dissolved due to metal ammine formation.

Bacteriology of ferromanganese nodules from the Indian Ocean

Abstract Bacteriological investigations of the ferromanganese nodules collected from the Indian Ocean indicate that the microbial populations associated with the nodules are, in general, comparable to those of the Pacific and Atlantic Oceans. Both Mn(II)‐oxidizing and MnO2‐reducing psychrotrophic bacteria were present in the nodules. The maximum percentage of oxidizers was noticed on the surface of the nodules. The sediments harbored more inactive forms. Members of Vibrio, Enterobacteriaceae, Bacillus, Micrococcus, Sta‐phylococcus, Arthrobacter, and coryneforms were encountered in the present study. Most of the isolates were able to grow on a wide range of sodium chloride concentrations (0 to 10%). The isolates elaborated a number of hydrolytic enzymes, namely, amylase, gelatinase, lipase, and phosphatase. The dominance of the gram‐positive group is attributed to terrigenous influences. The present study clearly indicates that Indian Ocean nodules also harbor a variety of heterotrophic bacteria capable of...

Separation of iron and manganese from sulphate solutions obtained from indian ocean nodules

Leach liquors obtained by sulphuric acid pressure leaching of Indian Ocean manganese nodules were treated for iron and manganese separation. This separation was carried out by sequential precipitation. Iron was precipitated by pH adjustment using lime slurry. The separation is 99.5%, with about 6.7% loss of copper and 2% loss of cobalt. From the iron-free solution manganese was precipitated as manganese dioxide in the presence of an oxidising agent, potassium perdisulphate. Under optimum conditions manganese precipitation is quantitative. There is a loss of about 27% of the cobalt due to adsorption on the manganese dioxide matrix. Kinetics of precipitation and specific reaction rates have been determined. The loss of cobalt by adsorption has been shown by fitting the data to the classical adsorption equation due to Freundlich.

Leaching of manganese nodules in ammoniacal medium using glucose as reductant

Polymetallic Indian Ocean nodules can be leached in ammoniacal solution in the presence of glucose. The various parameters chosen for leaching studies were: amount of glucose, time, pH, temperature, concentrations of ammonia and ammonium salt, and particle size. The percentage extraction of copper, nickel and cobalt decreases when the glucose concentration is increased to more than 0.4 gramme per gramme of nodule at 338 K and 0.2 g/g at 358 K. The dissolution of copper has been found to be dependent more on the pH of the solution than on the total molarity of ammonia and the ammonium ion. Leaching temperatures above 373 K are disadvantageous for the extraction of copper and cobalt, whereas nickel extraction is about 95% even at 433 K. The rate of leaching for all three metals is independent of the particle size in the range studied. All the copper, about 90% of the nickel and 60% of the cobalt can be extracted under the following leaching conditions: temperature 358 K, time 4 h, initial ammonia concentration 2.5 M, ammonium chloride concentration 0.37 M and glucose 0.2 gramme per gramme of nodule.

Potential of Pacific Ocean Nodule, Crust, and Sulfide Mineral Deposits

This paper summarizes the main physical and economic features of manganese nodules, cobalt‐rich manganese crusts and marine polymetallic sulfide deposits in the Pacific region. The most favourable areas for deposits of commerical interest are shown on a map of the Pacific. The gross metal sales values of hypothetical mines are compared to estimated size of world metal markets in the year 2000. It is suggested that a prudent policy for the major developed‐country governments is to support research on those marine minerals that appear to have the potential to become a major source of minerals in the next century.

Oxidation state of marine manganese nodules

Analyses of the bulk oxidation state of marine manganese nodules indicates that more than 98% of the Mn in deep ocean nodules is present as Mn(IV). The samples were collected from three quite different areas: the hemipelagic environment of the Guatemala Basin, the pelagic area of the North Pacific, and seamounts in the central Pacific. Results of the study suggest that todorokite in marine nodules is fully oxidized and has the following stoichiometry: (K, Na, Ca, Ba) .33(Mg, Cu, Ni) .76Mn 5O 22(H 2O) 3.2.

Design and Scale-up of Three-Phase Reactors for Sea Nodules

A case history on the development of the Cuprion Process for the treatment of ocean nodules is discussed. In this process, the manganese oxide matrix in the ore is reduced by carbon monoxide in an ammonia-ammonium carbonate-seawater slurry. This reduction step lends the metal values accessible to the leach liquor, thereby leading to efficient extraction of the desired metals (nickel, copper, cobalt, and molybdenum). The development approach is discussed including generation of liquid-phase kinetic, gas-liquid mass transfer, and solid-phase reaction data. A mathematical simulation of the system suitable for scale-up and design is described. Implications with respect to design of the reactor system, process control, and pilot-plant verification are discussed.

Preliminary Characterization of Pacific Ocean Manganese Nodules

For the past year the Bureau of Mines, Avondale Research Center, has been doing extensive characterization on Pacific Ocean nodules from the Clarion-Clipperton fracture zone, which extends from off the coast of Mexico and Central America in a general east-west direction toward the Hawaiian Islands. These nodules are a potentially valuable new source of Ni, Co, Cu, and Mn. All of these metals are essential to the U.S. economy. Three million tons of nodules would produce about 75 percent of the domestic need for Mn, 10.0 percent for Ni, 1.2 percent for Cu, and 45 percent for Co.Manganese nodules (figure 1) are basically concretions of hydrous manganese oxides and appear to have a simple concentric layer growth structure forming around a nucleus. The growth rate ranges from 1 to 10 mm per million years depending on surrounding conditions. After deposition, only minor changes occur in a layer. These changes include replacement of some Mn by other metals such as Co, Ni and Cu in the water circulating through pores in the nodule. Some of the minerals deposited initially have partial replacement by oxides.

Processes to refine ocean nodules assessed

Processes to refine ocean nodules assessed

Processing of ocean nodules: A technical and economic review

A detailed comparison of ammoniacal, sulfuric acid and hydrochloric acid processes is presented by Kennecott researchers, who favor hydrometallurgical techniques over pyrometallurgical treatments

An electron microprobe study of the relationships between heavy metals and manganese and iron in soils and ocean floor nodules

Six soils, six manganese nodules derived from soils and two ocean floor nodules were analysed by electron microprobe techniques to determine inter-element relationships. Cobalt was related to manganese in all samples, and a considerable fraction of the total cobalt in the soils was associated with the manganese oxides. Nickel was related to manganese in all of the nodules and some of the soils. In the soils, although the concentrations of nickel were highest in the manganese oxides, a large proportion of the total nickel was actually associated with the iron oxides. Copper and particularly zinc accumulated in the iron oxides in the soils, but in the nodules these elements were associated with either manganese or iron, and in some cases with neither.

Process makes pure metals from ocean nodules

Process makes pure metals from ocean nodules