Abstract
The Metals Company is well-positioned to become the first company to collect deep-sea polymetallic nodules at commercial scale for critical mineral recovery. A high grade, abundant resource rich in nickel, copper, cobalt and manganese is contained in polymetallic nodules that sit unattached on the seabed at depths exceeding 4,000 meters in an area of the Pacific Ocean known as the Clarion Clipperton Zone. Over the past decade, TMC has developed and tested a custom flowsheet configuration that employs well-known, existing unit operations that are in use in nickel operations worldwide. The flowsheet involves processing the nodules pyrometallurgically at the front-end, first through a rotary kiln and then an electric furnace, which produces a nickel-copper-cobalt alloy and manganese silicate slag product. The manganese silicate is a saleable product that has previously been planned for use in the steel manufacturing supply chain. In light of recent market developments involving higher manganese content in battery cathodes and associated interest in manganese sulfate supply, TMC engaged Kingston Process Metallurgy (KPM) to conduct a bench scale testing program to determine if manganese sulfate can be generated from their manganese silicate product.
This works presents an overview of the KPM bench scale program, where the eventual flowsheet was developed almost entirely in house due to minimal existing literature. Following selection and optimization of multiple unit operations, the program ultimately culminated in the generation of high purity manganese sulfate crystals with a purity on assay basis of 99.98% and all impurities below detection. A brief overview of TMC’s manganese silicate product and its importance to the project’s economics and near-zero waste initiative, as well as a market analysis which led to execution of this program will also be discussed.