Sorting efficiency in mechanical sorting of construction and demolition waste

The requirements for the recycling of construction and demolition waste are tightening, and companies in the waste business have improved their performance to comply with new legislation. Construction and demolition waste includes various recyclable materials, such as metals, plastics and wood. However, effective material recovery requires functional and reliable technology for sorting in order to separate waste fractions into useful secondary materials or applications. This paper concerns the mechanical sorting efficiency of construction and demolition waste with a commercial mechanical sorting equipment consisting of a roller screening and an air separation unit. Sorting ability is studied with pre-sorted and crushed test material. Sieve analysis of pre-sorted test material is used to define particle size distribution before sorting. The quality criteria of construction and demolition waste vary greatly, depending on a number of factors which pose a challenge to the operation of the sorting system. The studied sorting equipment was found to be reliable for producing nine different fractions from pre-sorted and crushed material mixtures. The requirements for the purity level of the fractions and the profitability of utilization define the number of fractions to be sorted cost-efficiently. Typically, a compromise between cost and purity level has to be found.