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प्रश्न
State the role of silica in the metallurgy of copper.
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उत्तर १
In the metallurgy of copper, silica (SiO2) acts as an acidic flux during smelting and Bessemerisation.
During smelting, the roasted ore contains ferrous oxide (FeO) as an impurity. Silica combines with FeO to form ferrous silicate (FeSiO3), which is a fusible slag.
\[\ce{FeO + SiO2 -> FeSiO3}\]
The slag (FeSiO3) being lighter, floats on the surface of the molten matte and is removed easily.
Similarly, during Bessemerisation, FeO formed again reacts with SiO2 to form FeSiO3 slag, purifying the molten copper.
Hence, the role of silica is to remove iron impurities by forming a fusible slag of FeSiO3.
उत्तर २
During roasting, copper pyrites are converted into a mixture of FeO and Cu2O. Thus, acidic flux silica is added during smelting to remove FeO (basic). FeO combines with SiO2 to form famous silicate (FeSiO3) slag, which floats over molten matte.
संबंधित प्रश्न
The reaction,
Cr2O3 + 2Al → Al2O3 + 2Cr
(ΔGθ = -421kJ) is thermodynamically feasible as is apparent from the Gibbs energy value. Why does it not take place at room temperature?
Is it true that under certain conditions, Mg can reduce SiO2 and Si can reduce MgO? What are those conditions?
Why is the extraction of copper from pyrites more difficult than that from its oxide ore through reduction?
Write down the reactions taking place in different zones in the blast furnace during the extraction of iron.
Write chemical reactions taking place in the extraction of zinc from zinc blende.
The choice of a reducing agent in a particular case depends on thermodynamic factor. How far do you agree with this statement? Support your opinion with two examples.
The impurity that is added externally to remove the impurity already present in the ore is known as ____________.
In the metallurgy of aluminium ______.
Choose the correct option of temperature at which carbon reduces \[\ce{FeO}\] to iron and produces \[\ce{CO}\].
Wrought iron is the purest form of iron. Write a reaction used for the preparation of wrought iron from cast iron. How can the impurities of sulphur, silicon and phosphorus be removed from cast iron?
How is copper extracted from low grade copper ores?
Explain the following:
\[\ce{CO2}\] is a better reducing agent below 710 K whereas \[\ce{CO}\] is a better reducing agent above 710 K.
Explain the following:
Silica is added to the sulphide ore of copper in the reverberatory furnace.
Explain the following:
Carbon and hydrogen are not used as reducing agents at high temperatures.
Carbon deposition reaction taking place in ______.
Assertion: For the extraction of iron, haematite ore is used.
Reason: Haematite is a carbonate ore of iron.
