Geobiotechnical Recovery of Metals from Manganese Nodules: First Experiments

Christina Heller; Axel Schippers

doi:10.4028/www.scientific.net/AMR.1130.201

Paper Titles

Electrochemical Research on N-Type and P-Type Semiconductor Pyrite
p.179

In Situ Characterization of Relevance of Surface Microstructure and Electrochemical Properties of Chalcopyrite to Adsorption of Acidianus manzaensis
p.183

Factors Affecting the Selection of BIOX^® as the Preferred Technology for the Treatment of a Refractory Gold Concentrate
p.191

Base Metal Tank Bioleaching: From Laboratory Test Work to Commercialization
p.197

Geobiotechnical Recovery of Metals from Manganese Nodules: First Experiments
p.201

Saline Water Bioleaching with Thermophilic Fe(II) Oxidising Microorganisms
p.205

Role of Microbial Activity in Bioleaching of a Pyritic and a Pure Chalcopyrite Concentrate
p.209

Oxygen-Enriched Gas in Bioleaching Stirred Reactors and its Impact on the Consortium Behaviour
p.214

Organic Carbon Utilisation by Iron(II)-Oxidising Bacteria Sulfobacillus thermosulfidooxidans and Alicyclobacillus Strain FP1 that Inhabit Copper Sulfide Leaching Heaps
p.218

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Geobiotechnical Recovery of Metals from Manganese Nodules: First Experiments

Abstract:

Marine polymetallic nodules represent an important resource of the metals Ni, Co, Cu, Mn, Zn, Li, Mo, V and Zr. Nodules consist mainly of Mn-Fe oxy-hydroxide precipitations with valuable metals mostly present within the structure of these host minerals. To recover the favoured metals via hydrometallurgy it is necessary to dissolve the Mn-Fe oxy-hydroxides. To test nodules processing via bioleaching, nodules were sampled during a ship cruise to the German license area located in the Pacific Ocean in 2013. They were ground in a mortar, washed to remove seawater chloride, and afterwards sieved to obtain the particle size fraction of 63 to 315 µm. Bioleaching experiments were conducted under aerobic conditions in shake flasks at 2 % pulp density at 30°C in a basal medium. A mixed culture of acidophilic chemolithotrophic iron- and sulfur-oxidizing bacteria (Acidithiobacillus thiooxidans, At. ferrooxidans, Leptospirillum ferrooxidans, L. ferriphilum) and Acidiphilum cryptum was inoculated. Elemental sulfur was used as substrate for acid leaching via sulfuric acid production. At pH values between 1.5 and 2.2 during the experiment, 40 % Ni, 25 % Cu, 1.2 % Mn, 0.3 % Co, 1 % Fe, 70 % Zn and 70 % Zr were leached from the Mn-nodules after 56 days. In preparation for future reductive bioleaching under anaerobic conditions, chemical kinetic reaction experiments were conducted. Different amounts of Fe(II) were added to a certain amount of the Mn nodules. These experiments showed that Fe(II) chemically reduced Mn(IV) to Mn(II) at a stoichiometry of 2 to 1. This reaction is prerequisite for anaerobic leaching based on biological reduction of Fe(III) to Fe(II) coupled to sulfur oxidation (Ferredox process). Up to 82 % Ni, 98 % Co, 68 % Cu, and 97 % Mn were leached in these chemical experiments indicating that anaerobic reductive bioleaching of manganese nodules should be possible.