Deep-ocean polymetallic nodules form on or just below the vast, sediment-covered, abyssal plains of the global ocean. Polymetallic nodules primarily consist of precipitated iron oxyhydroxides and manganese oxides, onto which metals such as nickel, cobalt, copper, titanium and rare earth elements sorb. The enormous tonnage of nodules on the seabed, and the immense quantities of critical metals that they contain, have made them a target for future mining operations. Mining of polymetallic nodules has been spurred by the need for critical metals to support growing populations, urbanization, high-technology applications and the development of a green-energy economy. Nevertheless, an improved understanding of the affected ecosystems and their connectivity, as well as the environmental impacts of deep-ocean mining, is required before operations begin. Opportunities exist, however, to ensure that this new industry applies adaptive management to continually refine operations with the goal of environmental protection and invests in the development of green technologies for extractive metallurgy and mining. In this Review, we explore the chemical processes that control the concentration of critical metals in deep-ocean polymetallic nodules, discuss the mining and metallurgical techniques required, and highlight the opportunities and potential risks that are presented by this new industry.

深海多金属结核形成于全球海洋的广阔，沉积物覆盖的深渊平原上或正下方。多金属结核主要由沉淀的羟基氧化铁和氧化锰组成，镍，钴，铜，钛和稀土元素等金属吸附在其上。海底结核的巨大吨位以及其中所含的大量关键金属使其成为未来采矿作业的目标。为了支持不断增长的人口，城市化，高科技应用和绿色能源经济的发展，对关键金属的需求刺激了多金属结核的开采。但是，在开始运营之前，需要更好地了解受影响的生态系统及其连通性以及深海采矿对环境的影响。但是，存在机会来确保这个新行业应用适应性管理来以环境保护为目标不断完善运营，并投资开发用于提取冶金和采矿的绿色技术。在这篇评论中，我们探讨了控制深海多金属结核中关键金属浓度的化学过程，讨论了所需的采矿和冶金技术，并重点介绍了这个新行业带来的机遇和潜在风险。