Full definition
A vibrating screen is a critical equipment in the mining and aggregate industries, designed to separate bulk materials based on particle size. This separation process utilizes one or more screen decks, which can be made from various materials such as mesh, plates, or modular media. The primary function of a vibrating screen is to allow undersized particles to pass through the screen while retaining oversize particles on the top. The operation of the screen is facilitated by vibration, which can vary in amplitude from 3 to 6 mm and frequency from 700 to 1,200 RPM, depending on the specific design and application requirements. The movement of the screen can be circular, linear, or elliptical, ensuring effective material flow across the screen surface. This vibration also helps to minimize blinding, a condition where the screen openings become clogged with material, thus enhancing the screening efficiency.
Vibrating screens utilize different types of screen media, each offering distinct advantages based on the application. Woven wire screens made from steel are the most common due to their cost-effectiveness and excellent open area for material flow. Polyurethane panels, with a hardness of 85-95 Shore A, offer a significantly longer lifespan—up to 3 to 5 times that of wire screens—especially in fine screening applications. They are also self-cleaning and produce lower noise levels during operation. Rubber panels, made from natural rubber (NR) or Styrene-Butadiene Rubber (SBR), are ideal for coarse screening applications where heavy impacts occur, providing noise reduction benefits. Lastly, perforated plates made from thick steel or polyurethane are used for very coarse scalping operations, effectively handling large particle sizes.
The capacity of a vibrating screen is influenced by several factors, including the deck area, screen opening size, and the characteristics of the material being processed. Screen openings can range from as small as 0.075 mm (200 mesh) to over 200 mm, allowing for versatile applications. The design of the screen can vary as well; inclined screens typically operate at angles between 15 and 25 degrees, utilizing gravity to assist in material flow, while horizontal screens are designed for lower height applications that enhance efficiency. Banana screens, featuring a variable slope, provide the highest capacity per unit area, making them ideal for operations requiring high throughput. Leading brands in the vibrating screen market include Metso Outotec, Sandvik, Deister, and Derrick, known for their innovative solutions tailored to fine screening needs. The manufacturing of polyurethane and rubber screen panels is undertaken by companies like Metso, Tema Isenmann, Polydeck, and Sandvik, ensuring a diverse selection of high-quality materials suitable for various mining applications.