Chemical Processing of Critical Minerals

Chemical processing is the stage where refined metals and intermediate compounds are converted into the precise chemical forms required by downstream manufacturers. The specifications are exacting: a lithium-ion battery cathode manufacturer requires lithium hydroxide monohydrate with a minimum purity of 56.5 percent lithium hydroxide and maximum impurity levels measured in parts per million. A permanent magnet producer needs neodymium metal with 99.5 percent purity or higher. A semiconductor fabricator demands gallium of 99.9999 percent (6N) purity. Meeting these specifications requires sophisticated chemical engineering, rigorous quality control, and deep process expertise that has been cultivated over decades, predominantly in East Asian facilities.

Battery-Grade Material Production

The explosive growth of lithium-ion batteries for electric vehicles and energy storage has made battery-grade chemical production one of the fastest-expanding segments of the critical minerals value chain. The principal battery chemicals include lithium hydroxide monohydrate (LiOH.H2O), lithium carbonate (Li2CO3), cobalt sulfate (CoSO4), nickel sulfate (NiSO4), manganese sulfate (MnSO4), and high-purity spherical graphite. Each of these must meet stringent purity requirements, as even trace impurities can degrade battery performance, cycle life, and safety.

Lithium hydroxide production begins with either spodumene concentrate (from hard-rock mining) or lithium carbonate (from brine extraction). The spodumene route involves calcination at approximately 1,050 degrees Celsius to convert alpha-spodumene to the more reactive beta phase, followed by sulfuric acid roasting, water leaching, purification, and causticization to produce lithium hydroxide. The brine route converts lithium carbonate to lithium hydroxide through reaction with calcium hydroxide (lime) in a causticization process. Both routes require multiple stages of impurity removal, including precipitation, ion exchange, and crystallization, to achieve battery-grade purity.

Cobalt and nickel sulfate production for battery precursor manufacturing typically involves dissolving refined cobalt or nickel metal in sulfuric acid, followed by crystallization. Alternatively, mixed hydroxide precipitate (MHP) or mixed sulfide precipitate (MSP) from nickel laterite HPAL operations can be redissolved and purified to produce battery-grade sulfates. The quality requirements are particularly stringent for impurities such as iron, copper, zinc, calcium, and sodium, which must be reduced to levels below 10 parts per million in most cathode precursor specifications.

Cathode and Anode Precursor Manufacturing

Battery-grade chemicals are used as feedstocks for cathode precursor production, which represents the next step toward finished battery cells. Cathode precursors, primarily nickel-cobalt-manganese (NCM) or nickel-cobalt-aluminum (NCA) hydroxides, are produced through co-precipitation processes where solutions of nickel, cobalt, and manganese sulfates are simultaneously precipitated as mixed hydroxides under carefully controlled pH, temperature, and agitation conditions. The resulting precursor particles must have precise composition, morphology, particle size distribution, and tap density to produce cathodes with optimal electrochemical performance.

China dominates cathode precursor production, with companies such as CNGR Advanced Material, Huayou Cobalt, GEM, and Brunp Recycling (a subsidiary of CATL) controlling the majority of global capacity. South Korea's EcoPro BM and L&F Energy Solution and Japan's Sumitomo Metal Mining are significant non-Chinese producers. Efforts to establish cathode precursor manufacturing in Europe and North America are underway, driven by the European Battery Regulation, the U.S. Inflation Reduction Act, and automaker preferences for localized supply chains.

Rare Earth Chemical Processing

After separation, individual rare earth elements exist as oxides, chlorides, or carbonates. Converting these to the metallic form required for permanent magnets involves additional chemical processing steps. Rare earth oxides are first dissolved in hydrochloric or nitric acid, purified through further solvent extraction if necessary, and precipitated as fluorides. The fluoride salts are then reduced to metal through calciothermic or electrolytic reduction processes. Neodymium-praseodymium (NdPr) alloy production via molten salt electrolysis is particularly important, as NdPr alloy is the primary feedstock for sintered NdFeB permanent magnets used in electric vehicle motors, wind turbine generators, and defense systems.

Producing magnet-grade rare earth alloys requires extremely tight control over oxygen, carbon, and other impurity levels, as these affect the magnetic properties of the final product. The alloy is typically cast into ingots or strip-cast flakes, which are then processed into magnets through powder metallurgy. This entire chain, from separated oxide to finished magnet, is overwhelmingly concentrated in China, which produces over 90 percent of the world's rare earth permanent magnets.

Specialty Chemical Production

Beyond batteries and magnets, critical minerals require chemical processing into a wide range of specialty products. High-purity gallium and germanium for semiconductors undergo zone refining, a process where a molten zone is repeatedly passed through a solid ingot, progressively concentrating impurities at one end to achieve purities of 99.9999 percent or higher. Tungsten carbide powder for cutting tools is produced by carburizing tungsten metal powder with carbon at temperatures above 1,400 degrees Celsius. Vanadium electrolyte for redox flow batteries is manufactured by dissolving vanadium pentoxide in sulfuric acid and precisely adjusting the oxidation state through electrolytic reduction.

Titanium dioxide pigment, the world's most important white pigment, is produced from ilmenite or rutile through either the sulfate process or the chloride process. Zirconium chemicals for ceramics, refractories, and nuclear applications are manufactured from zircon sand through chlorination or alkaline fusion. Each of these chemical conversion pathways requires specialized knowledge, equipment, and quality control protocols that represent significant barriers to entry for new producers.

Quality Control and Certification

The chemical processing stage is where supply chain quality is ultimately determined. Battery manufacturers impose rigorous qualification processes on chemical suppliers, typically requiring 6 to 18 months of sample testing and production audits before approving a new source. This qualification timeline creates significant inertia in supply chains: even when new chemical processing capacity comes online, it cannot immediately contribute to supply until downstream customers have completed qualification. This dynamic explains why supply chain diversification efforts take longer to produce results than the construction timelines of new plants alone would suggest.

Industry standards for battery-grade chemicals continue to tighten as battery technology advances. Higher-nickel cathode chemistries such as NCM811 and NCA require even lower impurity levels than earlier formulations. Solid-state batteries, which are expected to enter mass production in the late 2020s, may impose still more demanding purity requirements on lithium and other chemical inputs. Chemical processors that can consistently meet these evolving specifications will command premium pricing and preferred supplier status, while those that cannot will be relegated to lower-value commodity markets.