Question

In the extraction of copper, the copper matte is a mixture of:
(a)- Copper (II) sulfide and iron (II) sulfide
(b)- Copper (II) sulfide and iron (III) sulfide
(c)- Copper (I) sulfide and iron (II) sulfide
(d)- Copper (I) sulfide and iron (III) sulfide

Answer 1

Hint: Copper sulfide is oxidized with a metal that is more reactive than the copper element. Smelting is also involved in this process. Arsenic and antimony are the impurities that are present during the refining. Copper matte is made of $C{{u}_{2}}S$and $FeS$.


Complete step by step answer:

The sulfide ore i.e., copper pyrites after the concentration by froth flotation process is roasted in a reverberatory furnace when copper pyrites are converted into a mixture of \[FeS\]\[C{{u}_{2}}S\] and which, in turn, are partially oxidized.

\[2FeCu{{S}_{2}}+{{O}_{2}}\to C{{u}_{2}}S+2FeS+S{{O}_{2}}\]

\[2FeS+3{{O}_{2}}\to 2FeO+2S{{O}_{2}}\]

\[2C{{u}_{2}}S+3{{O}_{2}}\to 2C{{u}_{2}}O+2S{{O}_{2}}\]

Since iron is more reactive than the copper, \[FeS\] is preferentially oxidized to \[FeO\] than\[C{{u}_{2}}S\] to \[C{{u}_{2}}O\]. If at all any \[C{{u}_{2}}O\] is formed, it combines with\[FeS\] and is changed back to \[C{{u}_{2}}S\].

\[C{{u}_{2}}O+FeS\to C{{u}_{2}}S+FeO\]

Thus, the roasted ore mainly contains \[C{{u}_{2}}S\] and  along with unreacted \[FeS\] 

The roasted ore is then mixed with silica (flux) and some powdered coke and heated strongly in a blast furnace. This process is called smelting. During smelting combines with silica to form fusible ferrous silicate slag.

\[FeO+Si{{O}_{2}}\to FeSi{{O}_{3}}\]

At the temperature of the furnace, the entire mass melts, and two layers of molten mass are formed. The slag being lighter makes the upper layer which can be withdrawn from the slag whole from time to time. The lower molten layer is called copper matte. It chiefly consists of \[C{{u}_{2}}S\]  of and some unchanged \[FeS\].

So, the copper matte has Copper (II) sulfide and iron (II) sulfide.

Therefore, the correct answer is an option (a)- Copper (II) sulfide and iron (II) sulfide


Note: Recovery of copper from matte:
To obtain pure copper from matte, the molten matte is transferred to a besimmer converter which is a pear-shaped furnace made up of steel and lined inside with silica. It is mounted on a horizontal axle and can be tilted in any position. It is fitted with small pipes called tuyeres through which a blast of hot air and fine sand is admitted.