UPSC Prelims 2021 Q17: Environment & Ecology – Pollution & Waste Management
- (a) 1 and 2 only
- (b) 2 and 3 only
- (c) 1 and 3 only
- (d) 1, 2 and 3
Answer: (b) 2 and 3 only
Explanation
Copper Smelting: Environmental Concerns
| Concern | Valid? | Explanation |
|---|---|---|
| 1. Carbon monoxide (CO) release | FALSE | Copper smelting primarily emits sulphur dioxide (SO2), particulate matter and arsenic. CO is characteristic of incomplete combustion (vehicles, biomass), not copper smelting. |
| 2. Copper slag leaching heavy metals | TRUE | Slag contains arsenic, lead, cadmium, chromium, zinc which can leach into soil and groundwater if improperly disposed. Slag heaps near Sterlite plant (Tuticorin) were a major concern. |
| 3. Sulphur dioxide (SO2) release | TRUE | Copper is mined as sulphide ore (chalcopyrite CuFeS2). Smelting releases SO2 as the sulphur oxidises. This causes acid rain and respiratory problems. |
Only statements 2 and 3 are correct.
Answer: (b) 2 and 3 only.
Why each option is right or wrong
- (a) Incorrect. CO is not the main pollutant from copper smelting - SO2 is.
- (b) CORRECT. Slag leaches heavy metals (2) and smelting releases SO2 (3). These were the core issues in the Sterlite Copper Tuticorin controversy (2018).
- (c) Incorrect. Statement 1 (CO) is wrong.
- (d) Incorrect. Statement 1 is wrong - CO is not the primary copper smelting pollutant.
Key point
Copper smelting = SO2 + heavy metal leaching from slag. NOT CO (that is vehicles/biomass). Chalcopyrite (CuFeS2) is the main ore; smelting oxidises sulphur, releasing SO2 = acid rain risk. Slag contains As, Pb, Cd.
Remember
Copper smelting concerns are (2) slag leaching heavy metals into soil/groundwater and (3) sulphur dioxide release causing acid rain. Statement (1) about carbon monoxide is wrong - CO is a combustion pollutant, not a smelting pollutant. Answer: 2 and 3 only.
Common mistakes
- Confusing CO (combustion pollutant) with SO2 (smelting pollutant). Copper smelting is a chemical process, not combustion.
- Not knowing the Sterlite (Vedanta) Tuticorin case - 2018 police firing, plant permanently closed by TN government over SO2 and slag concerns.
- Missing that smelting SO2 emissions are a major raw material for sulphuric acid manufacture - India's copper plants recover SO2 as H2SO4.
Exam tip
Copper smelting = SO2 (acid rain, respiratory) + Slag (heavy metals) + Arsenic. Sterlite Tuticorin closure (2018) is a landmark environmental litigation case. Also study red mud (bauxite processing), fly ash (thermal), tailings (mining) for pollution questions.
Sources
- MoEFCC - Charter on Corporate Responsibility for Environmental Protection
- Central Pollution Control Board - Industry Sector Guidelines: Copper