Processing Metals
Design & Technology: AQA GCSE, topic 4.4.2
Processing Metals
Metal processing involves a series of steps to transform raw metal materials into usable products.
Mining
- Metal ores are extracted from the earth's crust through mining.
- Depending on the type of metal, mining methods include open-pit mining, underground mining, and placer mining.
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Crushing and grinding
- The extracted ores are crushed and ground into smaller particles.
- This facilitates further processing.
- Crushing and grinding increase the surface area of the ore.
- This allows for more efficient extraction of the metal.
Concentration
- The desired metal is usually present in the ore with other minerals.
- Concentration techniques are employed to separate the valuable metal from the rest of the ore.
- For example, froth flotation, gravity separation, and magnetic separation.
Smelting
- Smelting is the process of extracting the metal from its concentrated ore by melting it in a furnace.
- Smelting reduces the metal oxide to its elemental form using a reducing agent.
- An example of a reducing agent would be carbon monoxide.
- Smelting separates the impurities and produces a metal-rich product.
- The metal-rich product is called the 'matte' or 'bullion'.
Refining
- The matte or bullion obtained from smelting might contain impurities.
- These impurities need to be removed to achieve the desired metal purity.
- Refining techniques are used to remove impurities like sulphur, carbon, or other metals.
- Refining techniques include electrolysis, fractional crystallisation, and chemical processes.
Processing Metals
Metal processing involves a series of steps to transform raw metal materials into usable products. The specific process can vary depending on the type of metal.
Shaping and forming
- After the metal has been purified, it can be shaped and formed into the desired product.
- Shaping and forming techniques include:
- Casting.
- Forging.
- Rolling.
- Extrusion.
- Machining.
- These techniques allow for the metal to be moulded, shaped, or cut into specific forms and dimensions.
Heat treatment
- Heat treatment processes are employed to enhance the metal's properties.
- For example, hardness, strength, and ductility.
- Heat treatment processes involve annealing, tempering, and quenching.
- By heating and cooling the metal, these processes achieve the desired mechanical properties.
Surface Treatment
- Surface treatments are applied to improve the metal's appearance.
- Surface treatments also improve the metal's resistance to corrosion.
- Surface treatment processes include:
- Plating.
- Painting.
- Powder coating.
- Anodizing, and galvanising.
Assembly and finishing
- Metal components are usually assembled with other materials to create a finished product.
- Assembly processes involve:
- Welding.
- Soldering.
- Fastening.
- Adhesive bonding.
- After assembly, final finishing processes are applied to enhance the aesthetics and protect the metal.
- Finishing processes include polishing and coating.
Test yourself on Processing Metals
What process removes impurities like sulphur and carbon?
What process is employed to enhance the metal's properties?
What process improves the metal's appearance and resistance to corrosion?