Chemical and Metal Refining

electrowinning · chlor-alkali · battery metals

Much of metal and chemical refining is already electrochemistry: the product is made by electric current. Its carbon footprint is set by the grid it runs on, which is why refining capacity follows cheap power.

Log-scale chart of electricity per ton of product: copper electrorefining about 0.35 MWh, copper electrowinning about 2 MWh, chlorine from membrane cells about 2.5 MWh, zinc electrowinning about 3.2 MWh, aluminum smelting about 14 MWh, hydrogen electrolysis about 52 MWh. Values follow from Faraday charge per ton times cell voltage, plus current and auxiliary losses. ELECTRICITY PER TON OF PRODUCT, LOG SCALE Copper electrorefining~0.35 MWh Copper electrowinning~2 MWh Chlorine, membrane cell~2.5 MWh Zinc electrowinning~3.2 MWh Aluminum smelting~14 MWh Hydrogen electrolysis~52 MWh 0.1 1 10 100 MWh Faraday charge per ton times cell voltage, plus current and auxiliary losses.
Copper EW
~2 MWh/t
Chlorine
~2.5 MWh/t
Lithium refining in China
74%
Hub
Industry

Finding

Electrochemical refining needs no fuel switch, only clean firm power, and China's control of battery-metal refining rests partly on cheap, coal-heavy electricity

Copper and zinc electrowinning, copper electrorefining, chlor-alkali and aluminum smelting all pass direct current through cells; energy per ton is fixed by Faraday's law and cell voltage. A copper electrowinning cell runs near 2 V, an electrorefining cell near 0.3 V, which is why winning copper from leach solution takes about six times the power of refining anode copper.

Battery-metal refining is a mix of electrochemistry and heat. Spodumene is roasted near 1,050 °C to convert it before leaching, nickel and cobalt sulfates come from pressure leaching and solvent extraction, and cathode precursors are calcined in kilns. China refines about 74% of lithium chemicals and 76% of cobalt, and Indonesia's HPAL plants, mostly Chinese-owned (Huayou, GEM, Lygend), now supply much of the world's battery nickel intermediate.

Chlor-alkali is one of the largest single electricity users in chemistry: membrane cells split brine into chlorine, caustic soda and hydrogen at about 2.5 MWh per ton of chlorine, and the hydrogen is a usable by-product. Texas is the US center of it: Olin at Freeport and the plants along the Houston Ship Channel. Tesla's lithium hydroxide refinery near Corpus Christi is covered on AustinIO.

Battery metals

Lithium, nickel and cobalt refining

These steps feed cathode active material for NMC, NCA and LFP cells.

Battery metal refining steps
StepEquipmentProductEnergy note
Spodumene conversionRotary kiln near 1,050 °C, acid roast, leachLithium hydroxide or carbonateKiln is the main fuel load; electric kilns in development
Brine processingEvaporation ponds or direct lithium extraction (DLE)Lithium carbonatePonds use sun; DLE uses pumps and electricity
Nickel and cobalt (HPAL)Autoclaves, solvent extraction, crystallizersMHP, nickel and cobalt sulfateSteam and acid plants; Indonesia, Chinese-owned
Nickel and cobalt electrowinningElectrolytic cells, rectifiersCathode-grade metalFully electric
Precursor calcinationElectric roller hearth or rotary kilnsCathode precursor and CAMMostly electric in Chinese plants

Electrolysis

Electrowinning and chlor-alkali

Energy per ton is set by cell voltage and current efficiency.

Electrochemical refining processes
ProcessCell voltageElectricity per tonNotes
Copper electrorefining~0.3 V~0.35 MWhPurifies smelter anode copper to 99.99% cathode
Copper electrowinning (SX-EW)~2.0 V~2 MWhRecovers copper from leach solution; no smelter needed
Zinc electrowinning~3.3 V~3.2 MWhStandard route for nearly all primary zinc
Chlor-alkali, membrane cell~3 V~2.5 MWh per ton chlorineReplaced mercury and most diaphragm cells
Aluminum smelting (Hall-Heroult)~4 V~14 MWhLargest electrolytic industry; China about 60% of output
Rare earth metal electrolysisMolten fluoride saltVariesMakes NdPr metal from oxide; almost all in China

Refiners

Major refiners and producers

Chinese companies lead in most battery-metal clusters; Western and Chilean firms lead in copper and chlor-alkali.

Major refiners by cluster
ClusterCompaniesNotes
LithiumGanfeng, Tianqi, Yahua, Albemarle, SQM, Rio Tinto (Arcadium)China refines about 74%; Tesla and Albemarle building US hydroxide capacity
Nickel and cobaltHuayou Cobalt, GEM, CNGR, Jinchuan, Glencore, Vale, Nornickel, Sumitomo Metal MiningCobalt refining about 76% in China; Indonesian HPAL growing fast
Chlor-alkaliOlin, OxyChem, Westlake, Formosa Plastics, INEOS, Tata Chemicals, Xinjiang ZhongtaiMembrane cells; China is the largest producer
CopperCodelco, Freeport-McMoRan, Jiangxi Copper, Tongling, Zijin, Southern Copper, KGHM, AurubisChina refines about 47% of world copper
ZincKorea Zinc, Glencore, Nyrstar, Hindustan Zinc, Teck, Boliden, Zhuzhou SmelterElectrowinning is standard
Rare earthsChina Northern Rare Earth, China Rare Earth Group, Lynas, MP MaterialsChina about 84% of magnet rare earth refining; MP and Lynas separate outside China

Sources

Sources and scope

Scope
Chemical and Metal Refining
Sources
IEA Global Critical Minerals Outlook; USGS Mineral Commodity Summaries; Euro Chlor; company reports; energy values computed from Faraday's law
Updated
October 2026