By Matt Mayo, Chris Meadows and Celie Reid, Triple/S Dynamics, Inc. |
The chemical process industries (CPI) have many applications that require classifying or separating solid materials. Examples of separation or classification processes include those operations that attempt to isolate specific material fractions according to particle size, scalp off the coarse fraction of a material stream, de-dust the fine fraction of a material stream or remove the contamination from a material stream. For instance, dry separation is required in recycling processes for heavy metals, depicted in Figure 1. Dry separation methods can basically be broken down into three main types of mechanical separation procedures: air classification, screening and specific-gravity separation.
FIGURE 1. A common dry separation process is the recycling of heavy metals,
such as copper
Process engineers are routinely challenged with the ubiquitous problem of how to most effectively and efficiently perform particle sizing, along with addressing concerns about the removal of unwanted contaminants from a material stream. This article provides background on the different techniques and equipment used for dry separation, and also guides engineers in addressing some specific dry-separation issues.