Previous Year Question
Why is there a concern about copper smelting plants?
They may release lethal quantities of carbon monoxide into environment.
The copper slag can cause the leaching of some heavy metals into environment.
They may release sulphur dioxide as a pollutant.
Select the correct answer using the codes given below.
1 and 2
2 and 3
1 and 3
1, 2 and 3
Correct Answer: B
Detailed Solution
Copper smelting involves processing concentrated copper ore at high temperatures to extract copper.
Many major copper ores are sulphide minerals, such as chalcopyrite.
During the roasting and smelting of these ores, sulphur is oxidized to form sulphur dioxide.
Therefore, copper smelting plants may emit sulphur dioxide as an air pollutant. Hence, Statement 3 is correct.
Sulphur dioxide can affect the respiratory system and contributes to the formation of fine sulphate particles and acid rain in the atmosphere.
During smelting, unwanted minerals in the ore combine with flux to form slag.
Copper slag may contain residual quantities of lead, arsenic, cadmium and other metals along with iron and silica.
Under improper storage or disposal conditions, rainwater may leach these metals and carry them into soil and water.
Therefore, Statement 2 concerning the leaching of heavy metals from copper slag is correct.
Copper smelting may also generate dust, fine particles and metal-bearing emissions.
Carbon monoxide can form through incomplete combustion, but the release of its ‘lethal quantities’ into the environment is not a general and characteristic concern associated with copper smelting plants.
Therefore, Statement 1 is not correct.
Capturing sulphur dioxide and converting it into sulphuric acid can reduce air emissions.
Safe storage of slag, leaching tests, metal recovery and scientific disposal can reduce the risk of soil and water pollution.