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Translated
Smelting Copper from Malachite — From Green Ore to Red Metal
How to reduce malachite (Cu₂CO₃(OH)₂) to metallic copper using charcoal reduction. This technique has been used since 5000 BCE and was the foundation of the Copper Age and Bronze Age. Covers ore preparation, crucible setup, charcoal fuel, temperature management at 1085°C+, pouring, and ingot recovery. The second step in the copper chain after collecting malachite.
Advanced
6-8 hours
Instructions
1
1
Understand the chemistry
Understand the chemistry
Malachite decomposes when heated: Cu₂CO₃(OH)₂ → 2CuO + CO₂ + H₂O (at ~300°C). The resulting copper oxide (CuO) is then reduced by carbon monoxide from burning charcoal: CuO + CO → Cu + CO₂. Copper melts at 1085°C. Total copper yield from pure malachite is approximately 57.5%.
2
2
Crush the malachite
Crush the malachite
Break malachite into pieces smaller than 1 cm using a hammer and anvil. The finer the crush, the faster and more complete the reduction. Use a mortar and pestle for the final crush if available. Aim for pea-sized or smaller fragments.
Materials for this step:
Malachite Ore (crushed)2 kilogramTools needed:
Geological Hammer
Mortar and Pestle3
3
Prepare the crucible
Prepare the crucible
Use a clay crucible that can withstand 1200°C+. A graphite-clay crucible is ideal. The crucible should hold at least 500 ml. If making your own, mix fireclay with sand (2:1 ratio) and fire it slowly in a kiln to 1000°C before use. Pre-fired crucibles crack less.
Materials for this step:
Clay Crucible (refractory)1 piece4
4
Layer ore and charcoal in the crucible
Layer ore and charcoal in the crucible
Place a 2 cm layer of charcoal pieces at the bottom of the crucible. Add a layer of crushed malachite (2-3 cm). Top with another layer of charcoal. The charcoal both provides carbon for reduction and protects the copper from re-oxidation. Fill to about 2/3 full.
Materials for this step:
Hardwood Charcoal5 kilogram
5
5
Build or prepare the forge
Build or prepare the forge
You need a forge or furnace capable of reaching 1100-1200°C. A simple charcoal forge with forced air (bellows or blower) works well. The crucible sits in a bed of burning charcoal with additional charcoal piled around and above it. The air supply must be controllable.
Materials for this step:
Charcoal for Forge20 kilogram
Tools needed:
Bellows or Air Blower
6
6
Put on safety equipment
Put on safety equipment
Copper smelting involves extreme heat, toxic fumes, and molten metal. Wear: leather apron, leather gauntlet gloves, face shield, safety boots (no synthetic materials). Work outdoors or in a well-ventilated space. Copper oxide fumes cause metal fume fever if inhaled. Keep a bucket of dry sand nearby for spill containment.
Tools needed:
Leather Apron
Leather Gauntlet Gloves
Face Shield
Dry Sand Bucket7
7
Light the forge and preheat
Light the forge and preheat
Light the forge charcoal and bring it to full heat over 30-45 minutes with gentle bellows action. Place the loaded crucible into the forge once the coals are glowing white-hot. Pack charcoal tightly around the crucible. Increase bellows speed gradually.
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8
Maintain temperature for 2-3 hours
Maintain temperature for 2-3 hours
Keep the forge at 1100-1200°C for 2-3 hours. The malachite first decomposes (green changes to black CuO at ~300°C), then the CuO reduces to copper as temperature climbs. Add charcoal to the forge as needed to maintain heat. The crucible contents will shrink as CO₂ gas escapes.
9
9
Check for completion
Check for completion
After 2-3 hours, carefully lift the crucible lid with tongs and peek inside. You should see a bright orange-red pool of molten copper beneath a layer of slag (glassy dark material). If you see unmelted green or black chunks, continue heating for another 30 minutes.
Tools needed:
Long-Handled Tongs10
10
Prepare the ingot mold
Prepare the ingot mold
While the copper melts, prepare a sand mold or a flat stone depression for pouring. Preheat the mold with a torch to prevent thermal shock cracking. A simple bar-shaped mold carved into a sandstone block works well. Ensure the mold is completely dry — any moisture causes explosive splattering of molten metal.
Tools needed:
Sandstone Ingot Mold11
11
Pour the copper
Pour the copper
Using crucible tongs, lift the crucible from the forge. Tilt slowly to pour molten copper into the mold. The dark glassy slag floats on top and can be held back with a stick while the copper flows under it. Pour steadily — interrupted pours create cold shuts (weak seams).
Tools needed:
Crucible Tongs12
12
Let the ingot cool
Let the ingot cool
Allow the copper ingot to cool in the mold for at least 30 minutes. Do not quench in water — rapid cooling makes copper brittle with internal stresses. Air cooling produces a softer, more workable metal. The copper surface oxidizes to a dark red-brown as it cools.
13
13
Remove and clean the ingot
Remove and clean the ingot
Once cool enough to handle (below 100°C), remove the ingot from the mold. Brush off adhering sand and slag with a wire brush. The ingot should have the characteristic salmon-pink color of fresh copper on freshly exposed surfaces. Any dark patches are trapped slag or oxide inclusions.
Tools needed:
Wire Brush14
14
Weigh and assess yield
Weigh and assess yield
Weigh the clean copper ingot. From 2 kg of good malachite ore, expect 800-1000 g of copper (40-50% yield, accounting for slag losses and impurities). Pure malachite would yield 1150 g, but field-collected ore is rarely pure. Record the yield for future optimization.
Tools needed:
Kitchen Scale15
15
Test the copper quality
Test the copper quality
Hammer the edge of the ingot on an anvil. Good copper deforms plastically without cracking — it is one of the most malleable metals. If it cracks, it contains too much slag or oxide. File a small area to expose fresh metal — pure copper is salmon-pink. A green tinge indicates incomplete reduction.
Tools needed:
Heavy Hammer (2-3 kg)
Metal File16
16
Store the copper ingot
Store the copper ingot
Copper oxidizes slowly in air (forming green patina over months). For short-term storage, keep dry. For long-term, coat with a thin layer of oil. Label with date, source ore, and weight. This copper is ready for casting, hammering into sheet, or alloying with tin to make bronze.
Materials
5- 2 kilogramPlaceholder
- 1 piecePlaceholder
Tools Required
16- Placeholder
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Connected Blueprint Materials
You can swap these in
Can't get one of the materials? Swap it for an equivalent — these work just as well.
- Instead of Geological Hammer, try:
Dead Blow Hammer - Instead of Metal File, try:
Material Hardness Tester File Set - Instead of Face Shield, try:
CAN-BUS Shield
Ardumoto - Motor Driver Shield
SparkFun Weather Shield
LiPower Shield - Instead of Dry Sand Bucket, try:
Bucket (5-gallon) - Instead of Digital Kitchen Scale, try:
Iron Scale
Livestock Scale - Instead of Charcoal, try:
Activated Charcoal Powder - Instead of Wire Brush Set (3-Piece), try:
Pollination Brush - Instead of Crucible Tongs, try:
Jar Tongs
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