Extraction of Metals and Their Uses

Flashcards covering the extraction processes, ores, definitions, and alloys based on the lecture notes on metal extraction and usage.

Bauxite

The chief ore of aluminium, which is a hydrated aluminium oxide with the formula $Al_2O_3 \times 2H_2O$.

Electrolytic method

An extraction method used for metals high in the reactivity series, including sodium, potassium, calcium, magnesium, and aluminium.

Reduction method

An extraction method used for moderately reactive metals such as zinc, iron, lead, and copper, typically using coke or carbon monoxide.

Cryolite

Sodium hexafluoroaluminate ($Na_3AlF_6$), used to dissolve aluminium oxide to lower its melting point from $2054\,^{\circ}C$ to about $900\,^{\circ}C$.

Hall-Heroult cell

The electrolytic cell used for the electrolysis of aluminium oxide, featuring a steel tank lined with carbon as the cathode.

Charge

A mixture of iron ore, coke, and limestone that is fed into a blast furnace for the extraction of iron.

Haematite

A principal ore of iron containing iron (III) oxide ($Fe_2O_3$).

Tuyeres

The pipes through which a blast of hot air is introduced into the blast furnace.

Slag

A byproduct such as calcium silicate ($CaSiO_3$) formed by the reaction between calcium oxide and silica impurities in the ore.

Pig iron

Also known as cast iron, this is impure iron from the blast furnace that is brittle and has low tensile strength.

Wrought iron

The purest form of commercial iron, which is malleable and can be forged or welded when hot.

Steel

An alloy of iron and carbon that is tough, malleable, and can be tempered to increase strength.

Alloy

A homogeneous mixture of two or more metals, or a mixture of a metal and a non-metal.

Zinc blende

A common ore of zinc consisting of zinc sulphide ($ZnS$).

Froth flotation

A process used to concentrate ores by attracting ore particles to the surface of oil-water bubbles, leaving impurities behind.

Blister copper

Impure copper obtained after reduction, named for its appearance caused by escaping gases during cooling.

Brass

An alloy consisting of approximately $65\%$ copper and $35\%$ zinc.

Bronze

An alloy primarily composed of copper and tin.

Corrosion

The chemical wearing of metals resulting from the reaction between metals and atmospheric oxygen in the presence of moisture.

Rust

Hydrated iron (III) oxide ($Fe_2O_3 \cdot nH_2O$) formed when iron reacts with oxygen in the presence of water.

Sacrificial Protection

A method of preventing corrosion by coating a metal with a more reactive metal that loses electrons in preference to the protected metal.

Galvanising

The process of coating iron or steel with a thin layer of zinc to prevent contact with air and moisture.

Electroplating

A process using electricity to coat the surface of a metal that corrodes with a layer of a non-corroding metal like chromium.

Silica

Silicon dioxide ($SiO_2$), a sand impurity present in iron ore that reacts with calcium oxide to form slag.

Duralumin

A light, non-corrosive alloy with high tensile strength composed of $96\%$ aluminium, $3.5\%$ copper, and $0.5\%$ magnesium.