Question

A fluid energy mill is used for:

• A. Cutting
• B. Grinding
• C. Ultra-grinding
• D. Crushing

Hint:

Think about the scale of the particle size reduction. Crushers handle large chunks, grinders produce finer particles, and fluid energy mills are at the extreme end, producing ultrafine powders.

Answer 1

The Correct Option is C

Step 1: Understand the purpose and mechanism of a fluid energy mill.
A fluid energy mill, also known as a jet mill or micronizer, is a type of grinding mill used for producing very fine particles, typically in the micrometer and sub-micrometer range. It operates by using high-velocity gas or steam jets to impact particles against each other, causing them to fracture and reduce in size.
Step 2: Differentiate between cutting, grinding, ultra-grinding, and crushing.
Cutting: A process of separating a material by a shearing action, often using a sharp tool.
Grinding: A size reduction process that typically produces particles in the millimeter to micrometer range. Various types of mills are used for grinding, such as ball mills, hammer mills, and roller mills.
Ultra-grinding: A term used for grinding processes that achieve extremely fine particle sizes, typically in the micrometer and sub-micrometer range. This is finer than conventional grinding.
Crushing: A size reduction process used for relatively coarse materials, typically reducing them to smaller lumps or fragments. Crushers are used for larger feed sizes than grinders.
Step 3: Relate the mechanism of a fluid energy mill to the size reduction categories.
Fluid energy mills utilize high-energy fluid streams to cause particle attrition through impact and abrasion. This method is particularly effective for achieving very fine particle sizes, well into the micrometer and sub-micrometer range. While it is a form of grinding, the fineness of the product typically places it in the category of ultra-grinding.
Step 4: Evaluate the given options.
Option 1 (Cutting): A fluid energy mill does not operate by cutting.
Option 2 (Grinding): While it is a type of grinding, "ultra-grinding" is a more specific and accurate description due to the very fine particle sizes achieved.
Option 3 (Ultra-grinding): This accurately describes the capability of a fluid energy mill to produce extremely fine powders.
Option 4 (Crushing): Fluid energy mills are not used for the initial, coarser size reduction typically referred to as crushing.
Step 5: Select the correct answer.
A fluid energy mill is used for ultra-grinding.