In closed circuit grinding as compared to open circuit grinding, the
A. Specific surface of product is more
B. Product has lesser size uniformity
C. Production rate at a given limiting size is lower
D. Operation is economical
Answer: Option A
Solution (By Examveda Team)
The correct answer is Option A: Specific surface of product is more.Here's why:
Closed circuit grinding involves a classifier (like a sieve or cyclone) that separates the ground material.
Only the material *larger* than the desired size is sent back for further grinding.
Open circuit grinding, on the other hand, grinds everything in one go without separation.
Think of it like this:
In closed circuit:
Only the coarser particles are re-ground.
This continuous re-grinding of coarse particles ensures a finer product.
Finer product means more surface area per unit mass (specific surface). So, the specific surface is higher.
In open circuit:
Everything is ground together, leading to a wider range of particle sizes.
Here's why the other options are incorrect:
Option B: Product has lesser size uniformity: Closed circuit gives *better* size uniformity because oversized particles are re-ground.
Option C: Production rate at a given limiting size is lower: Closed circuit often has a *higher* production rate at a specific size because it efficiently processes only oversized particles.
Option D: Operation is economical: While the initial investment might be higher, closed-circuit grinding can be more economical in the long run due to *increased efficiency and reduced over-grinding* but it's not the primary benefit directly related to the grinding process itself. The increased specific surface area is the most direct result.
This Question Belongs to Chemical Engineering >> Mechanical Operations
The correct answer is:
A. Specific surface of product is more
Explanation:
Closed circuit grinding involves returning oversized material back to the mill after classification (e.g., using a classifier or cyclone). This leads to more thorough grinding and finer product, as opposed to open circuit grinding, where all the material exits the system after one pass.
Option-wise Breakdown:
A. Specific surface of product is more ✅
True. Since finer particles are produced, the total surface area per unit mass (specific surface) increases.
B. Product has lesser size uniformity ❌
False. Closed circuit grinding improves size uniformity by removing fines and returning only coarse particles for further grinding.
C. Production rate at a given limiting size is lower ❌
False. Closed circuit allows higher production rates for the same product fineness because it avoids overgrinding of already fine particles.
D. Operation is economical ❌
False. Although it improves efficiency, the additional equipment and energy use make it less economical in simple terms compared to open circuit systems.
✅ Final Answer: A. Specific surface of product is more