Name: Occurrence of Metals
Uploaded: 2019-07-19
Duration: 3 min 22 s
Description: Metals mostly occur in a combined state, but sometimes they can also occur in the free state. It is termed the native state of the metal. Let's see the videos.

Question

Aluminium is the most abundant metal in the Earth’s crust. Iron is next. Iron and aluminium are extracted from their ores in large quantities. The tablebelow summarises the two extraction processes.Most of the iron produced is converted into steels. How is this carried out?

Accepted Answer

Impurities in the iron from the Blast Furnace include carbon, sulphur, phosphorus and silicon. These have to be removed by heating in BOF, the basic oxygen furnace quite similar to blast furnace with little difference in parameters.

Removal of sulphur-Sulphur has to be removed first in a separate process. Magnesium powder is blown through the molten iron and the sulphur reacts with it to form magnesium sulphide. This forms a slag on top of the iron and can be removed. $Mg + S \overset{heat}{\to} MgS$

Removal of carbon -The still impure molten iron is mixed with scrap iron (from recycling) and oxygen is blown onto the mixture. The oxygen reacts with the remaining impurities to form various oxides. The carbon forms carbon monoxide. Since, this is a gas it removes itself from the iron. This carbon monoxide can be cleaned and used as fuel gas. $C + O_{2} \overset{heat}{\to} CO$

Elements like phosphorus and silicon react with oxygen to form acidic oxides. These are removed using quicklime (calcium oxide) which is added to the furnace during the oxygen blow. They react to form compounds such as calcium silicate or calcium phosphate which form a slag on top of the iron. $P + O_{2} \overset{heat}{\to} P_{2} O_{5} Si + O_{2} \overset{heat}{\to} {SiO}_{2} {SiO}_{2} + CaO \overset{heat}{\to} {CaSiO}_{3}$

In order to make variety of steel depending upon its use and purpose some additives in definite % are added like chromium nickel cobalt etc. even the percentage of carbon is changed and adjusted.

Aluminium is the most abundant metal in the Earth’s crust. Iron is next. Iron and aluminium are extracted from their ores in large quantities. The tablebelow summarises the two extraction processes.Most of the iron produced is converted into steels. How is this carried out?

Important Questions on Making Use of Metals

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