Question
Question: Bessemerisation is carried out for: i.Fe ii.Cu iii.Al iv.Silver A. i, ii B. ii, iii C....
Bessemerisation is carried out for:
i.Fe
ii.Cu
iii.Al
iv.Silver
A. i, ii
B. ii, iii
C. iii, iv
D. i, iii
Solution
Bessemerisation is a process in which air is blown to a molten copper matte that is kept in the Bessemer converter. The other products that remain like FeS get oxidized and removed as a slag (FeSiO3) in the final step of smelting. It is also used to convert iron to steel.
Complete step by step answer:
In case of iron, the bessemerisation is used for the manufacturing of steel from iron. In this process pig iron from the blast furnace is directly run into the Bessemer converter. It is a pear-shaped furnace about 20 feet high and 10 feet in diameter. The converter is made up of steel plates lined inside with free bricks. Airblast can be admitted from the base through a number of holes called tuyers. To begin with, the molten pig iron is run into the converter keeping it in the horizontal position. It is rotated so that it is now vertically upward. The blast of air is admitted through the tuyeres. Due to the continuous blowing of air, the impurities like Carbon, Silicon, Manganese get oxidized and are removed. Manganous oxide and Silica combine together to form manganese silicate which is removed as slag. Carbon monoxide forms burn with a blue flame at the mouth of the converter. The reactions involved are:
2C+O2→2CO ; 2Mn+O2→2MnO
Si+O2→SiO2 ; MnO+SiO2→MnSiO3
When the whole carbon is oxidized to CO then a calculated quantity of carbon is added to it.
When mixing is taken place, product results are known as manganese steel. It is
poured by tilting the convertor.
Bessemerisation is used in the extraction of pure copper which is also known as blister copper. The molten copper matte obtained is introduced in a small pear-shaped furnace which is made up of steel plates known as Bessemer converters. In this step, a blast of air and sand is blown into it by the means of tuyeres in the side little above the button. This helps in the complete oxidation of sulphides. The furnace is mounted on trunnions and can be titled in any position. Ferrous oxide forms react with sand to form ferrous silicate (slag). Cuprous oxide is partially oxidized to Cu2O which reacts with the remaining sulphide to form metallic copper.
Cu2S+2Cu2O→SO2+6Cu
The molten copper is poured out in sand moulds by tilting the convertor. It is then allowed to cool. Dissolved sulphur dioxide is given off from the solidified copper leaving blisters on the surface which is known as blister copper and it is 98 % pure.
Bessemerisation process is not carried out for Silver and Aluminium.
After discussing we can say Bessemerisation is carried out for iron and copper.
So, the correct answer is Option A.
Note: Pig iron is the molten iron tapped out from the furnace. It consists of 2.6 – 4.3 % of carbon along with Manganese, Silicon, Sulphur and Phosphorus. It can be cast into moulds which on remelting and cooling produces cast iron.