UPSC Prelims 2021 Question:

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.

Explanation:

• Smelting is an energy-intensive process used to refine ore into usable metal. The copper concentrates are fed through the flash smelting furnace with oxygen-enriched air. The carbon source is oxidized in two stages. First, carbon (C) combusts with oxygen (O2) in the air to produce carbon monoxide (CO). Second, the carbon monoxide reacts with the ore (e.g. Fe2O3) and removes one of its oxygen atoms, releasing carbon dioxide (CO2). This leads to a small amount of carbon monoxide, not a lethal quantity. So, statement 1 is not correct.
  
  
• Extractive metallurgical and smelting processes can be highly polluting activities. Some facilities that carry out metal and smelting processes are known to emit high quantities of air pollutants such as hydrogen fluoride, sulfur dioxide, oxides of nitrogen, offensive and noxious smoke fumes, vapors, gases, and other toxins. A variety of heavy metals: lead, arsenic, chromium, cadmium, nickel, copper, and zinc are also released by the facilities. So, statement 2 is correct.
  
  
• Organic vapors and sulfur oxides result from secondary smelting roasting operations and fuel combustion. It results in the release of fine airborne particles, nitrogen oxides, sulfur dioxide and carbon monoxide, which can together cause smog. So, statement 3 is correct.
  
  

Therefore, option (2) is the correct answer.

Relevance: Vedanta puts on sale its Sterlite copper smelting plant in Tamil Nadu.

Subject: Environment | Pollution