How copper is made
Most copper ore is less than 1 percent copper, so mines grind mountains and float the metal out on bubbles.
- stations
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- things upstream
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- raw sources
- 4
- steps from the ground
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The short version
Copper ore averages under 0.6 percent copper, so it is crushed to powder and floated in frothy tanks to make a concentrate. A smelter melts the concentrate into matte, converts it to 98 percent blister copper, and fire-refines it. The final purification is electrolytic, producing cathodes of 99.99 percent copper.
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Crush the ore to powder
The average grade of copper ore this century is below 0.6 percent. Rock is ground to particles under 100 micrometers, fine enough that each grain is one mineral.
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Float the copper sulfide
The powder is mixed into a slurry with chemicals that make the copper sulfide grains repel water. Air is pumped through, and the copper grains cling to bubbles and rise as a froth that is skimmed off. The waste rock sinks as tailings.
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Smelt the concentrate to matte
The concentrate is melted in a flash furnace or similar smelter with oxygen-enriched air. Iron and sulfur burn off, and a heavy copper-rich matte sinks under a floating layer of slag.
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Convert it to blister copper
Air is blown through the matte to burn out the remaining iron and sulfur. What is left is about 98 percent copper. It is called blister because sulfur dioxide escaping on cooling leaves a broken surface. The gas is captured and made into sulfuric acid.
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Fire-refine in an anode furnace
In a furnace, remaining sulfur and iron are oxidized away, and then oxygen is removed by blowing natural gas or another reducing agent through the melt, in a step called poling. The metal is cast into flat anodes.
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Plate pure copper by electrolysis
The anodes hang in baths of copper sulfate and sulfuric acid, facing thin sheets of pure copper or stainless steel. Current drives copper off the anode and onto the cathode, and valuable silver, gold, selenium and tellurium fall to the bottom as anode slime.
99.99% pure cathode
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Worth repeating
- More than 95 percent of all the copper ever mined and smelted has been extracted since 1900.
- A copper smelter makes sulfuric acid from the sulfur it burns out of the ore, and sulfuric acid is also what leaches copper out of oxide ores.
- Oxide ores can skip the smelter, since they are leached in heaps with sulfuric acid and the copper is plated out from the solution.
Back to the ground
Follow every input upstream and copper starts as these 4 raw sources.
Everything it is made of See it on the map
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Where it comes from
- Chileat least one-third of world production
- United Statessecond-largest producer
- Indonesiathird-largest producer
- Perufourth-largest producer
2005, copper mine production, per the British Geological Survey.
Where it goes next
Copper feeds 34 lines directly and reaches 111 things in total.
Further down the line
Keep walking
Sources
Cite this page: "How copper is made." Assembly Line, 2026-11-03. https://assemblyline.org/make/copper