Question

The most effective concentration step for sulfide ores is

• A. Froth flotation
• B. Magnetic separation
• C. Gravity separation
• D. Electrostatic separation

Hint:

Remember the specific ore types associated with each concentration method: Froth flotation for sulfide ores, magnetic separation for magnetic ores, and gravity separation for dense oxide ores.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks for the most effective method for the concentration of sulfide ores. Concentration (or ore dressing) is the process of removing the unwanted gangue particles from the ore.
Step 2: Detailed Explanation:
Let's evaluate the suitability of each method for sulfide ores:

• Froth Flotation: This method is based on the principle of selectively wetting mineral particles. Sulfide ores are generally hydrophobic (water-repelling), or can be made so by adding 'collectors'. When air is bubbled through a slurry of the powdered ore, the hydrophobic sulfide particles attach to the air bubbles and rise to the surface to form a froth, which is then skimmed off. The hydrophilic gangue particles are wetted by water and settle at the bottom. This method is highly effective and widely used for concentrating sulfide ores like galena (PbS), chalcopyrite (CuFeS\(_2\)), and sphalerite (ZnS).
  
• Magnetic Separation: This method separates minerals based on differences in their magnetic properties. It is effective for ferromagnetic ores like magnetite (Fe\(_3\)O\(_4\)) or for separating magnetic impurities like wolframite from cassiterite. Most sulfide ores are not sufficiently magnetic for this process to be effective.
  
• Gravity Separation: This method relies on the difference in specific gravity between the ore and the gangue. It works well for heavy oxide ores like cassiterite (SnO\(_2\)) and hematite (Fe\(_2\)O\(_3\)). While there is a density difference for sulfide ores, froth flotation is generally far more efficient and selective.
  
• Electrostatic Separation: This method separates particles based on their electrical conductivity. It is used in specific applications, like separating conducting minerals from non-conducting ones, but it is not the primary or most effective method for sulfide ores in general.
  

Step 3: Final Answer:
The froth flotation process is uniquely suited to the surface properties of sulfide minerals and is the most common and effective industrial method for their concentration.