Chemistry
The following flow chart shows the process of extraction of zinc. Out of the 5 steps, 2 steps are incorrect. Identify and correct them.
Metallurgy
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Answer
| Step | Process in Chart | Status | Correct Process |
|---|---|---|---|
| 1 | Pulverisation | Correct | Pulverisation |
| 2 | Leaching | Incorrect | Froth Floatation |
| 3 | Calcination | Incorrect | Roasting |
| 4 | Reduction by Coke | Correct | Reduction by Coke |
| 5 | Refining by Electrolysis | Correct | Refining by Electrolysis |
1st Incorrect Step: Leaching
Correction: Froth Floatation
Reason: Zinc blende is a sulphide ore. Sulphide ores are preferentially wetted by oil and are concentrated using the Froth Floatation process rather than leaching.
2nd Incorrect Step: Calcination
Correction: Roasting
Reason: Calcination is used for carbonate ores (heating in the absence of air). Since Zinc blende is a sulphide ore, it must be heated strongly in the presence of excess air to convert it into zinc oxide (ZnO). This process is called Roasting.
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