Why can copper be extracted from copper pyrites ($\ce{CuFeS2}$) but not iron? Is there some intuitive logic behind it?
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1$\begingroup$ Without more context, the question is in danger to be closed for lack of details. // The site expects that you write explicit compact summary results of your prior effort, based on your knowledge and searching for existing related info or answers. It would prevent others to tell you what you already know or what you could easily find yourself. Effort not shown can be considered as effort not done and such a question may be closed. How do I ask a good question?. $\endgroup$– PoutnikCommented May 4, 2022 at 12:41
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$\begingroup$ Economics. Copper is expensive compared to iron. There are far better, cheaper sources of iron. But sources of copper are rarer. $\endgroup$– matt_blackCommented May 5, 2022 at 12:16
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2 Answers
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Quoting from this source
Copper pyrites contains only 2-3% of copper. The rest of ore contains iron as sulphide, silica, silicious materials, sulphur, arsenic etc as impurities. Froth floatation is carried out by xanthate and pine oil. The froth is collected and dried when concentrated ore is obtained which contains 25-30% of Cu. Then smelting of the roasted ore in blast furnace is done. The minor reactions that occured during roasting continue here. Ferrous oxide combines with sand to form a fusible slag. Cuprous oxide formed combines with ferrous sulphide to give ferrous oxide and cuprous sulphide. This is because iron has more affinity for oxygen than copper.
FeO+SiO2→FeSiO3
During roasting, copper pyrite converts into a mixture of FeS+Cu2S→FeO+Cu2O
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1$\begingroup$ Copper has high value . Iron has low value and if contaminates with sulfur even a negative value, so recovery of this iron would be an economic mistake. $\endgroup$ Commented May 4, 2022 at 14:11
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Chalcopyrite contains 34.5% Cu, 30.5% Fe, and 35.0% S. The mineral is the principal source of copper metal, and one of the major source of sulfur. Since copper is in majority, it is called "copper ore" from where copper is extracted. The iron portion is converted into iron(II) silicate and removed as slag.
$$\ce{2CuFeS2 + 2SiO2 + 4O2 → Cu2S + 2FeSiO3 (slag) + 3SO2}$$
If you want to extract iron, you need iron ore which are rich in iron content.
For more detailed explanation, see my answer: Extraction of copper from chalcopyrite
answered May 5, 2022 at 2:50