CHAPTER XLI 



IRON, NICKEL, COBALT 



IRON Fe 



Occurrence. Iron as a free metal is rarer than ffold [fsee p. 54). 

 Masses of iron are found in meteorites, lately arrived on earth 

 from airless space. Minute particles of the metal may be detected 

 in igneous rocks, freshly broken open. Compounds of iron are 

 very widely distributed. Pyrite FeS 2 (fools' gold) is used mainly 

 as a source of sulphur for sulphuric acid. The ores which yield 

 iron itself are: 



erric oxide) > rejd haematite. Red when pulverized. 

 2Fe 2 O 3 ,3H 2 (hydrated ferric oxide), brown haematite. 

 Fe 3 4 (magnetic oxide of iron), magnetite. Black when pul- 



verized. 

 FeCOs (ferrous carbonate), spathic iron ore. 



The carbonate, mixed with clay (clay iron-stone), furnishes most 

 of the iron in Great Britain, but less than one per cent of it in the 

 United States. The ore is first calcined to produce the oxide. 



The Blast Furnace. Coke is used to reduce the oxides and 

 as fuel. The carbon monoxide CO, produced by the burning of 

 the coke and air, is the actual reducing agent: 



Fe 3 4 + CO *= 3FeO + CO 2 . 

 FeO + CO =* Fe + C0 2 . 



Since the ores contain rocky material (gangue), such as silica 

 Si0 2 and silicates of aluminium, limestone is added in the 

 proportion required to give a fusible slag. 



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