Particle classification is an important unit operation in many fields of technology where size reduction or enlargement takes place: in chemical engineering, the oil industry, mining and metallurgy, the food industry, environmental technology and so on. In this work, the fundamentals of wet classification are described and a scientific basis for solving classification problems is presented. For the practical engineer, there is an overview of the technical solutions available. The text begins with a discussion of the forces that affect a particle moving in a fluid and govern industrial classification processes. Understanding the effects of these forces and their use in classification makes it possible to use, modify and design classification processes. First, an ideal situation, free settling, is discussed in order to give the most basic relationships between the forces. Then, some corrections to this ideal free-settling condition are outlined. Different methods of measuring classifier performance are explained, both in terms of mass and distribution efficiencies.
The effects of sampling errors on efficiency values are outlined, along with methods to compute consistent classifier data. The construction of different classifier types, their operation and design is also discussed, with emphasis placed on hydrocyclones.