phosphoric ore

NAME:  Phosphoric ore.

ALTERNATIVE NAME: None.

LANGUAGE: Mining.

LOCATION: World wide.

CATEGORY: Mineral.

DISCIPLINE: Steelmaking/Fertilisers.

SHORT DESCRIPTION: Ores containing large deposits of phosphorus.

DESCRIPTION: Iron ores are among the most common ores to be found in the earth’s crust and many of them are close enough to the surface for them to be easily mined. 

As a result, man has been able to dig them up and use them to make metal products, for more than three thousand years, since the beginning of the Iron Age.  Some iron ores are more pure than others but they all contain, in varying degrees, other elements, one of which is phosphorus.

Naturally-occurring inorganic salts of phosphoric acid are known as phosphate minerals, of which there are over 150 species.  They yield primary phosphates, which are crystallised directly from the molten state, secondary phosphates, which are derived by water and heat, and rock phosphates, which result from the action of water on ancient bone material.

During the eighteenth and nineteenth centuries, when the industrial revolution happened in Western Europe and the United States, the presence of phosphorus in iron ore became a matter of great importance.  Much of the iron ore in Britain and northern Spain was particularly low in phosphorus and Swedish iron ores were valued for their purity. The largest deposits of phosphoric ores were found in Belgium, France and, particularly, Germany.

As the industrial revolution got under way and agricultural production grew, phosphorus became important as an agrochemical. In 1835, James Murray, a physician from Dublin, showed that rock phosphate could be combined with sulphuric acid to make superphosphate for fertilisers. And in 1840, the German chemist <investigated by> Liebig* suggested that bones could be substituted for phosphate rock. Phosphorus was also used to make matches.

Phosphoric ore became a serious consideration in the steel industry when <caused problems for> Bessemer* invented a method of making low-cost steel in 1856, but discovered that any phosphorous in the iron ore used for steelmaking made the metal brittle. This meant that the more pure ores readily available to the British, Spanish and the Swedes gave them an edge in steel manufacturing.

This all changed dramatically in 1879, when Sidney Thomas and <made viable by> Gilchrist* discovered how to remove phosphorus during the steelmaking process.  This meant that areas high in phosphoric ores suddenly became more important.  Lorraine, the French province that Germany had taken eight years before at the end of the Franco-Prussian War, contained particularly rich fields of phosphoric ore.  Thanks to the new process, the steel industry in northern France and Germany thrived, eventually overtaking that of Britain.

ONELINER: Phosphoric ores,  unwanted ingredient in steel

BIBLIOGRAPHY:

Encyclopaedia Britannica.

McGraw Hill Enclyclopedia of Technology.