In closed circuit grinding as compared to open circuit grinding, the

Answer: Option A

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.