From the electronics industry to transport, manufacturing, and machinery, the utility of copper (Cu) in our world is immense. This metal is found naturally in the Earth’s crust (50 parts per million), usually combined with zinc, sulfur, carbon, and oxygen. Copper magnetic material can sound confusing as the metal doesn’t have magnetic properties. However, it can get magnetised upon exposure to external magnetic fields.

A large percentage of the world’s copper comes from hot sulphur solutions and porphyritic stock in volcanic areas. Chile, Peru, and the United States are among the geographies with Cu. The metal is also found in Canada, Zambia, Congo, and Australia and is a core component of the economy of these countries.

The production of “red gold” – another name for copper – begins with mining. It can be open pit or underground. The former is standard, but the latter may be used when the ores are too deep and require digging shafts. Oxide and sulfide ores are the typical raw materials, comprising 0.5 to 2.0% copper. Here are the main types and steps in primary copper production:

1. For sulfide ores, more commonly used-

• Crushing: The ore gets crushed to loosen copper minerals.
• Froth floatation: Mix the crushed ore with water and chemicals like sodium ethyl xanthate, cresols, and aniline. It makes the copper particles water-repellent. Then, pass air through the mixture so the copper minerals attach to the bubbles and float to the surface.
• Thickening: The froth gets thickened into a concentrate.
• Smelting*: The concentrate gets smelted into anode slabs.
• Electrolytic refining: The slabs get refined into copper cathode slabs – 99.99% pure copper.

*Occasionally, roasting occurs before this stage to obtain “blister copper” with a copper percentage of 98.5 to 99.5%.

II. For oxide ores –

This production method (SX-EW) is more sustainable and environment-friendly. It also allows the processing of minerals with small percentages of copper.

• Heap leaching: This step uses sulfuric acid to separate copper from the ore.
• Solvent extraction: Extract the solvent from the leach and remove impurities.
• Electrowinning: Pass an electric current through the solvent to charge copper ions and plate them onto a cathode.

III. Recycling

A significant percentage of copper (around 1/3rd) gets produced secondarily using recycled scrap. The main steps here are smelting and refining.

Copper grades and percentage of purity

What makes copper unique? What are the benefits?

This reddish-metallic element and a Cu alloy deliver ingenious advantages in the industrial sector.

• Excellent conductor of heat and electricity: Half of the world’s copper is employed in the electrical industry. Inexpensive compared to competitor metals with good electrical conductivity
• Dependable resistance to corrosion from moisture, saltwater, non-oxidising minerals, and alkalis. (Eventually, it may rust into green copper oxide. It is also called verdigris or patina.)
• 100 % recyclable
• Antibacterial (MRSA, E. Coli, and influenza) and effective in controlling mussels, barnacles, and algae as an antifouling agent
• Good malleability and ductility
• High formability and straightforward to solder, bolt, crimp, etc.
• Durable and resilient, capable of handling wear and tear and delivering a long service life

Copper surface treatment

The preferred surface treatment for many copper applications is a protective layer of tin, nickel, or silver. Tin is inexpensive and also shows smooth soldering. Clear coatings of polymers or solvents, alkaline permanganate, and chromate baths are also feasible. The surface of this metal can be cleaned using commercial detergents.

You should not apply surface treatments like paint, wax, or lacquer if your application utilises the antibacterial properties of copper metal. These coatings can affect and diminish the properties of copper.

Copper vs pure copper

Pure or native copper has a copper content of at least 99.3%. Electrolytic copper, the highest grade of copper (>99.95%), has excellent conductivity and is used for making electrical wires. Another “pure” form is C101, or oxygen-free copper (less than 0.0005% oxygen, over 99.99% copper). It is incredibly close to the elemental copper.

Copper often exists as simple binary compounds, like copper oxide, sulfide, and chloride. Other sources of the metal are copper carbonates (carbon and oxygen) and complex copper minerals (with metals like iron, cobalt, silver, etc.).

Application of copper alloys

Creating alloys is a common industrial practice to boost chemical and metallurgical properties, like electrical conductivity, strength, and corrosion resistance. Copper alloys are widespread and numerous (400+), but brass (with zinc) and bronze (with tin) are the most common for boosting strength. Tin brass (3% tin) and silicone red brass (6% silicon) have admirable corrosion resistance. Likewise, the bronze family has variations that use phosphorus, aluminium, and silicon.
Copper nickel and nickel silver (10-20% Ni, also called Alapacca) are other coveted selections for marine environments and aesthetics, respectively. Finally, STOL or special alloys work in IT and automation.

• • Electrical wires, switches, relay springs, etc.
  • Electronic equipment and microprocessors of phones, PCs, etc.
  • Heating and cooling equipment like heat exchangers, air conditioners, and central heating systems
  • Automotive parts like brake systems and radiators
  • Architectural and construction applications like roofs, decorative elements, etc. – sought after for weather-resistance
  • Plumbing fittings, valves, and other bearings
  • Marine and shipbuilding equipment for resistance to saltwater
  • Tools and military applications due to its non-magnetic and non-sparkling properties
  • Brass gets used for household cooking utensils and electric kettles.
  • Brass is also customary for curtain rods, fasteners, door handles, and musical instruments.

• Bronze gets utilised for medals, statues, coins, bells, etc.