Difference Between Bauxite and Iron Ore

Main Difference – Bauxite vs Iron Ore

An ore is a naturally occurring solid material from which a metal or valuable mineral can be extracted profitably. An ore is a type of rock. Ores are extracted from earth via mining and then are refined to obtain important metals and minerals. Different types of ores have different elements. Bauxite and iron ore are two such types that are found naturally on earth. Bauxite is also known as aluminum ore and contains aluminum bearing minerals. Iron ore is a type of rock from which we can extract iron. The main difference between bauxite and iron ore is that bauxite is a source of aluminum whereas iron ore is a source of iron.

Key Areas Covered

1. What is Bauxite
– Definition, Composition, Processing
2. What is Iron Ore
– Definition, Different Forms of Iron, Smelting
3. What is the Difference Between Bauxite and Iron Ore
– Comparison of Key Differences

Key Terms: Aluminum, Aluminum Oxides, Bauxite, Hematite, Iron Ore, Iron Oxides, Magnetite, Smelting

What is Bauxite

Bauxite is an aluminum ore. It is a major source of aluminum. Bauxite is a rock composed of aluminum compounds. Bauxite is a mixture of hydrous aluminum oxides, aluminum hydroxides, clay minerals and insoluble materials such as quartz, hematite, etc. The aluminum-containing compounds in bauxite are as follows;

Gibbsite [Al(OH)₃]
Boehmite [γ-AlO(OH)]
Diaspore [α-AlO(OH)]

Apart from that, there are some trace amounts of the followings:

Anatase (TiO₂)
Ilmenite (FeTiO₃)

Bauxite has a white-grey appearance that is sometimes stained with orange, red or pink like colors. Usually, the mineral streak of bauxite is white, but the color may alter if iron is present (streak is the appearance of a mineral when it is finely powdered). Bauxite has a dull luster, and it is an opaque substance.

Figure 1: Bauxite Appearance

There are several types of bauxite ores that are named depending on the intended commercial applications:

Abrasive bauxite
Metallurgical bauxite
Cement bauxite
Chemical bauxite

Processing

In the processing of the bauxite ore, first the ore is obtained via mining, and then it is crushed. The crushed bauxite is then purified by Bayer process. This process includes the following steps:

Washing bauxite with hot sodium hydroxide solution (this causes the leaching of aluminum from bauxite)
Aluminum is precipitated from the resulting solution (precipitation of aluminum in the form of Al(OH)₃)
Then the precipitate is converted to alumina via calcination (Al₂O₃)
Alumina is dissolved in molten cryolite at 960 °C
Aluminum can be obtained from this solution via Hall-Heroult Process (in which metallic aluminum is yielded by passing an electric current through the solution to carry electrolysis.

What is Iron Ore

Iron ore is a rock which is a source of metallic iron. Metallic iron can be extracted from iron ores. Iron ores have different chemical compositions and different colors depending on the amount of iron present in the ore.

The iron in iron ores can be found in different forms:

Magnetite (Fe₃O₄)
Hematite (Fe₂O₃)
Goethite (FeO(OH))
Limonite (FeO(OH).nH₂O)
Siderite (FeCO₃)

Figure 2: A Hematite Rock

Ores containing a high percentage of iron can be directly fed to blast furnace for the production of metallic iron. Iron ores are mainly composed of oxides of iron. Iron can be obtained from these oxides via a process called “smelting”. Smelting is the process by which a metal is obtained at temperatures beyond the melting point from its ore. Here coke is used as a reducing agent. Coke is composed of carbon that can bind with oxygen and remove oxygen from iron oxides.

Definition

Bauxite: Bauxite is an aluminum ore.

Iron Ore: Iron ore is a rock which is a source of metallic iron.

Metal Source

Bauxite: Bauxite is a source of aluminum.

Iron Ore: Iron ores are sources of iron.

Composition

Bauxite: The major components of bauxite are oxides of aluminum.

Iron Ore: The major components of irons ores are oxides of iron.

Appearance

Bauxite: Bauxite has a white-gray appearance that is sometimes stained with orange, red or pink colors.

Iron Ore: Iron ores have very dark colors such as dark red.

Extraction Processes

Bauxite: Bayer process and Hall-Heroult Process are used to extract aluminum from bauxite.

Iron Ore: Smelting can be used to extract iron from iron ores.

Conclusion

Bauxite and iron ores are rocks that are used to extract important metal elements and other minerals. They have different appearances and physical properties depending on the chemical composition. The main difference between bauxite and iron ore is that bauxite is a source of aluminum whereas iron ore is a source of iron.

Reference:

1. “Bauxite.” Geology, Available here.
2. “Bauxite.” Wikipedia, Wikimedia Foundation, 25 Dec. 2017, Available here.
3. Muwanguzi, Abraham J. B., et al. “Characterization of Chemical Composition and Microstructure of Natural Iron Ore from Muko Deposits.” International Scholarly Research Notices, Hindawi, 3 Dec. 2012, Available here.

Image Courtesy:

1. “Bauxite” By ResourcesCommitteHouse (Public Domain) via Commons Wikimedia
2. “Hematite rock (Biwabik Iron-Formation, Paleoproterozoic, ~1.878 Ga; Thunderbird Mine, Mesabi Iron Range, Minnesota, USA) 1” by James St. John (CC BY 2.0) via Flickr