Q1: Trommels employ __________ for screening of materials.

ANS:C - punched plate

Trommels employ woven wire screens for screening materials. Here's a brief explanation of each option:

1. Fibrous Cloth:
   • Not typically used in trommels for screening materials. Fibrous cloth is more commonly used in filtration applications rather than for heavy-duty screening.
2. Woven Wire Screen:
   • This is the most common type of screening media used in trommels.
   • Woven wire screens are durable, have varying mesh sizes for different applications, and allow for effective screening of materials by size.
3. Punched Plate:
   • Punched plates are sometimes used for screening, but they are less common in trommels compared to woven wire screens.
   • They can be effective for certain applications but are generally not as versatile as woven wire screens.

Therefore, woven wire screens are the correct and most commonly used screening medium in trommels for screening materials. Woven wire screens are a type of screening media used extensively in various industrial applications for separating and sizing materials. Here's an explanation of woven wire screens:

1. Construction:
   • Woven wire screens are made from metal wires (usually steel, stainless steel, or high carbon steel) that are woven together to form a mesh.
   • The weaving process creates openings or apertures of various sizes and shapes within the mesh, depending on the application requirements.
2. Types of Weaves:
   • Plain Weave: The most common type, where wires are woven alternately over and under each other.
   • Twill Weave: Involves a diagonal pattern of weaving that provides increased strength and allows for finer mesh sizes.
   • Dutch Weave: Has a combination of coarse wires and fine wires woven together, creating a tight mesh structure suitable for precise filtration.
3. Advantages:
   • Durability: Woven wire screens are robust and can withstand high impact and abrasion, making them suitable for demanding applications.
   • Versatility: They come in a wide range of mesh sizes, from very coarse to very fine, allowing for precise control of particle size separation.
   • Customization: Can be customized with different wire diameters, aperture sizes, and weave patterns to meet specific screening requirements.
4. Applications:
   • Mining and Aggregates: Used in vibrating screens and trommels for sorting and classifying minerals, rocks, and aggregates by size.
   • Construction: Used in construction and demolition waste sorting.
   • Industrial: Used in food processing, pharmaceuticals, recycling, and other industries for separating and grading materials.
5. Maintenance:
   • Regular cleaning and maintenance are necessary to ensure optimal performance.
   • Depending on the material being screened, woven wire screens may require periodic replacement due to wear and tear.

In summary, woven wire screens are versatile and durable screening media that play a crucial role in various industries for efficient separation and sizing of materials based on their particle size characteristics. Their ability to withstand harsh conditions and their customization options make them widely preferred in industrial screening applications.