Bamboo Molecules for Efficient Reductive Leaching of Valuable Metals From Oceanic Manganese Nodules

ABSTRACT To address the issue of resource utilization of oceanic manganese nodules (OMN), a hydrometallurgical method using bamboo molecule as a green reducing agent is proposed for the reductive leaching of valuable metals from OMN. The bamboo fiber was hydrolyzed via a two‐step hydrolysis method into a molecular chain, and the optimal process conditions for the production of reducing sugars were systematically investigated. Based on these optimized hydrolysis conditions, the metal leaching conditions were further optimized. The results showed that the highest yield of reducing sugars was achieved by first reacting in a 70% mass fraction concentrated sulfuric acid system for 30 min, then transferring to a 20% sulfuric acid system, heating to 90°C, and continuing the hydrolysis for 1 h. Under the optimal biomass acid hydrolysis conditions, when bamboo molecules and OMN were mixed at a ratio of 0.4 g/g and leached at 90°C for 80 min, the leaching rates of Mn, Fe, Ni, and Co reached the highest, which were 98.8%, 36.3%, 99.3%, and 98.7%, respectively. This process has the advantages of low cost, environmental friendliness, and high metal recovery rate, providing a new technical approach for the efficient utilization of OMN.