Why is there a concern about copper smelting plants?
- 1.They may release lethal quantities of carbon monoxide into environment.
- 2.The copper slag can cause the leaching of some heavy metals into environment.
- 3.They may release sulphur dioxide as a pollutant.
Select the correct answer using the code given below.
Answer & explanation
Answer: (b) 2 and 3 only
Most copper comes from sulphide ores, so smelting them drives off sulphur dioxide, a major air pollutant. The glassy waste left behind, copper slag, still carries heavy metals that can contaminate soil and water if stored carelessly. Releasing lethal amounts of carbon monoxide is not the recognised hazard of these plants.
- ✗ 1. The air-pollution concern linked to smelting ores that contain sulphur is sulphur dioxide, not lethal quantities of carbon monoxide; UPSC's key treats statement 1 as wrong.
- ✓ 2. Copper slag (Ferro sand) contains arsenic, cadmium, chromium, cobalt, nickel, lead and zinc, and the CPCB guideline asks smelters to store slag on an impermeable base with a garland drain to prevent soil and groundwater contamination.
- ✓ 3. Roasting and smelting sulphide ores releases sulphur dioxide; the WHO lists the smelting of sulphur-bearing ores as a main source of SO2.
Remember · Copper smelters: sulphur dioxide (from sulphide ores) in the air, and heavy-metal leaching from slag heaps.
Sources
- WHO fact sheet: Ambient (outdoor) air pollution ↗ “It is produced from the burning of fossil fuels (coal and oil) and the smelting of mineral ores that contain sulfur.”
- CPCB (MoEFCC), Draft Guidelines on Management of Pyro-metallurgical Slags (Copper Smelters), May 2023, para 3.1 ↗ “Arsenic (ppm) 10 – 250 -- -- Cadmium 5 – 8 ppm 0.0002 – 0.0006 % -- Chromium 0.5 - 1.0 ppm 0.018 – 0.04 % -- Cobalt 100 – 200 ppm 0.020 – 0.069 % -- Nickel 25 – 50 ppm 0.020 – 0.028 % -- Lead 200 – 250 ppm … Implement appropriate measures, such as impermeable base and garland drain, in slag storage area to avoid fluid leakage and prevent soil and water / groundwater contamination.”
Question and answer: UPSC's official GS Paper I (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). ·