Most often, sieves are used in the separation process to separate substances into liquid and solid fractions. Sieves are usually made of perforated material – most commonly metal, but some manufacturers use plastic – with different hole diameters that allow different sized particles to pass through.
Depending on the type and size of waste, different sieves can be used to separate waste into fractions such as food waste, manure, paper and textile waste, wood waste and others.
The use of sieves in the separation process helps to improve the quality of the recyclable materials and simplify further processing.
There are several types of sieves, depending on the request. The choice of a particular type of sieve depends on the application and the requirements of the separation process.
Based on the material required for processing, the following types of sieves are used in the industry:
Separation (slotted or sleeper) sieves: used to separate bulk materials into different fractions – liquid and solid with different moisture levels – based on particle size.
Filter sieves: used to filter liquids or gases to get rid of impurities.
Vibrating sieves: used to separate bulk materials by vibrating them and feeding them through the sieve in the manner of a flour sieve.
Rotary sieves: used to separate wastewater from mechanical impurities, by rotating around the axis of the sieve.
Magnetic sieves: used to separate magnetic particles from bulk materials.
Slotted sieves are the most popular for use in separators, but they themselves can be manufactured in various forms depending on the purpose of the user. They can be categorised into flat, arc and cylindrical slotted sieves.
Flat slotted sieves are sieves with evenly spaced meshes slotted on a straight surface. They are commonly used to separate solids from liquids or to sort and separate powdery or granular materials. The opening size in flat sieves can be tailored to suit specific needs and requirements, making it a versatile tool in many industries: food processing, pharmaceuticals and agriculture.
Arc slotted sieves are sieves designed in the shape of an arc. They are typically used to separate larger particles and to process materials with higher flow rates. Arc slotted sieves provide a larger volume and mesh size compared to flat sieves, which helps to reduce material clogging and improve screening efficiency. These sieves are commonly used in food processing, agriculture and mining applications.
Cylindrical slotted sieves (or rotary sieves) are a type of sieve that uses a cylindrical drum as the separation object. The material fed into it by a screw is separated into different fractions depending on the size, shape and density of the particles or fibres. The cylindrical drum is covered with a screen mesh with a specific mesh size that determines the size range of the fraction to be separated. Material that is too large to pass through the mesh is discharged from the end of the drum, while the finer, separated portions can be collected for further processing.
Cylindrical sieves can be used in a wide variety of industries including food processing, agriculture, chemical and pharmaceuticals, and mining. They are particularly suitable for separating different fractions of mixed materials as well as maximising liquid removal from the waste being processed.
