Abstract
Efficient extraction of Ni, Co, Cu, and Mn from low-grade and refractory ores is a common technical challenge. The present study proposes an Acidithiobacillus ferrooxidans-coupled leaching of Ni, Cu, Co, and Mn from oceanic polymetallic nodules and low-grade nickel sulfide ore, and focuses on the electrochemical behavior of the ores in simulated bio-leaching solutions. In the dissolution of polymetallic nodules, A. ferrooxidans facilitates the diffusion of H+ and accelerates electron transfer, producing a decrease in charge transfer resistance and promoting the Mn(IV)-preceding reaction. The use of A. ferrooxidans is beneficial for lower impedance of sulfur-nickel ore, faster diffusion rate of product layer, and better transformation of the Fe3+/Fe2+ couple and S0/S2− couple. A. ferrooxidans increases the potential difference between the nodule cathode and sulfide anode, and increases electron liberation from the sulfide ore. This motivates a significant increase in the average extraction rates of Ni, Co, Cu, and Mn in the bacterial solution. The bio-leaching efficiencies of Ni, Co, Cu, and Mn were as high as 95.4%, 97.8%, 92.2% and 97.3%, respectively, representing improvements of 17.1%, 11.5%, 14.3% and 12.9% relative to that of the germ- and Fe(III)-free acidic 9 K basic system.
Highlights
Due to the danger of completely consuming obtainable resources, the extraction of Ni, Cu, Co, and Mn from low-grade and refractory ore has become a focal point [1]
Cu, Co, and other metals fill in the interstitial sites of the manganese oxide mineral lattice in ionic form, leading to the necessary destruction of the high valence manganese mineral lattice for the extraction of metals from polymetallic nodules [3]
At pH 2.2 the corrosion potential in A. ferrooxidansis is lower than the control by 0.25 V. It is can be claimed, based on these results, that A. ferrooxidans facilitates the diffusion of H+ to the MnO2 electrode interface
Summary
Due to the danger of completely consuming obtainable resources, the extraction of Ni, Cu, Co, and Mn from low-grade and refractory ore has become a focal point [1]. Cu, Co, and other metals fill in the interstitial sites of the manganese oxide mineral lattice in ionic form, leading to the necessary destruction of the high valence manganese mineral lattice for the extraction of metals from polymetallic nodules [3]. These metals are present in nodules in the forms of oxides, and in sulfur-nickel ore as sulfides. An economical alternative process must be developed, for low-grade polymetallic ores
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