Zinc is produced by mining ore from the earth, then using heat or acid to separate the metal from the minerals it’s locked inside. Global mine production reached about 12 million metric tons in 2024, with China, Peru, and Australia leading output. The process has two main paths: one uses electricity and acid, the other uses extreme heat and carbon. A growing share also comes from recycling steel industry waste.
Where Zinc Starts: The Ore
Nearly all zinc begins as sphalerite, a mineral made of zinc and sulfur that contains about 67% zinc by weight. It’s mined from underground or open-pit deposits, often alongside lead and copper ores. Other zinc-bearing minerals include smithsonite (a zinc carbonate at roughly 52% zinc) and hemimorphite (a zinc silicate at about 58% zinc), but these are far less common as commercial sources.
Once mined, the ore goes through crushing and a process called flotation, where ground-up rock is mixed with water and chemicals that cause zinc-rich particles to attach to air bubbles and rise to the surface. The result is a concentrate, a powder that’s much richer in zinc than the raw rock it came from. This concentrate is the starting material for both of the main production methods.
Roasting: Turning Sulfide Into Oxide
Before zinc can be extracted, the sulfur in sphalerite has to go. The concentrate is fed into a fluidized-bed furnace, where it reacts with oxygen at temperatures typically between 750 and 850°C. This converts zinc sulfide into zinc oxide, a powdery material called calcine. Sulfur leaves as sulfur dioxide gas, which is usually captured and turned into sulfuric acid for use later in the process or sold separately.
Temperature control during roasting matters more than you might expect. If the furnace runs too cool, zinc bonds with iron to form a compound called zinc ferrite that’s difficult to dissolve later. Too hot, and zinc silicates form instead, creating problems during filtration. The sweet spot produces calcine that’s mostly zinc oxide with small amounts of iron, cadmium, and other metal oxides mixed in.
The Acid Path: Leaching and Electrolysis
The most common route for producing zinc today is called the hydrometallurgical process, and it accounts for the majority of global refined zinc. It works by dissolving the roasted calcine in sulfuric acid, then using electricity to pull pure zinc out of the solution.
The calcine is mixed with sulfuric acid at a pH around 1.5 to 2.5 and heated to roughly 90°C. The zinc oxide dissolves readily, creating a zinc sulfate solution. But this liquid also picks up iron, copper, cadmium, cobalt, nickel, and trace amounts of rarer metals like germanium, indium, and gallium. All of these have to be removed before electrolysis can work properly.
Iron is the biggest contaminant. It’s removed through a technique called jarosite precipitation: by adjusting the pH and adding ammonia or an alkali, iron and heavy metals form an insoluble mineral that settles out and can be filtered away. Under typical conditions, about 57% of the iron is captured this way. The remaining impurities, including cadmium and copper, are removed in additional purification stages where zinc dust is added to the solution. These metals plate onto the zinc dust and are filtered out. Some of these byproducts, particularly indium and gallium, are valuable enough to be recovered and sold separately.
Once purified, the clean zinc sulfate solution flows into large electrolysis cells. Aluminum cathode sheets are submerged in the solution alongside lead-alloy anodes, and electric current is passed through. Over about 24 to 48 hours, pure zinc deposits onto the aluminum sheets. Workers strip off the zinc, melt it, and cast it into ingots. This method can produce Special High Grade zinc at 99.99% purity.
The Heat Path: Smelting in a Furnace
The alternative route uses carbon (in the form of coke) to chemically strip oxygen away from zinc oxide at very high temperatures. The most notable version is the Imperial Smelting Process, which has the advantage of extracting both zinc and lead from mixed ores in a single operation.
Roasted and sintered zinc-lead concentrate is loaded into a tall shaft furnace along with coke. As temperatures climb past 1,200°C in the lower zones, carbon reacts with zinc oxide, reducing it to zinc metal. At these temperatures, zinc becomes a vapor and rises out of the furnace with the exhaust gases. Lead oxide, meanwhile, is reduced to liquid lead that collects at the bottom of the furnace.
The zinc vapor is captured in an ingenious way: it enters a condenser where molten lead is continuously splashed through the gas stream. Zinc dissolves into the hot lead. The lead-zinc mixture is then cooled to around 450°C, at which point the zinc separates from the lead because the two metals become immiscible at lower temperatures. The zinc floats to the top and is skimmed off, while the lead is recycled back to the condenser.
This pyrometallurgical path produces zinc that’s less pure than the electrolytic method, closer to the Prime Western grade at 98% purity minimum. It can be further refined if higher purity is needed.
Zinc From Recycled Sources
Not all zinc comes from freshly mined ore. A significant and growing portion is recovered from industrial waste, particularly the dust generated by electric arc furnaces used in steelmaking. This dust is rich in zinc oxide and zinc ferrite because steel scrap often contains galvanized (zinc-coated) metal.
The dominant recycling technology is the Waelz process, which handles roughly 75% of the steel dust generated in electric arc furnaces worldwide. The dust is loaded into a large rotating kiln along with coke. As the kiln turns and heats up, the carbon reduces zinc compounds back to zinc metal, which vaporizes, exits the kiln in the gas stream, and re-oxidizes into zinc oxide powder. This powder is collected on bag filters and can then be fed into a standard leaching or smelting operation to produce refined zinc.
Newer approaches use electric arc resistance furnaces to process steelmaking dust, producing zinc oxide, an iron alloy, and slag as separate products with minimal solid waste.
Purity Grades and What They Mean
Refined zinc is sold in several standardized grades. The two most commonly referenced are Special High Grade, which must contain at least 99.99% zinc, and Prime Western, which requires a minimum of 98.0% zinc. Special High Grade is the standard for galvanizing steel, die-casting alloys, and chemical applications where trace impurities cause problems. Prime Western zinc is used in less demanding applications like certain brass alloys and oxide production.
Global refined zinc production was forecast at 13.7 million tons in 2024, slightly below estimated consumption of 13.8 million tons. China dominates both mining and refining, producing about 4 million metric tons of mined zinc concentrate annually. Peru, Australia, India, and the United States round out the top five mining nations.