Optimization and dust emissions analysis of the air jigging technology applied to the recycling of construction and demolition waste.

This work aims to evaluate the use of the air jigging technique, a density-based separation technology commonly applied in mineral processing, to upgrade the quality of mixtures (density and geometric properties) that represents the typical composition of construction and demolition waste (CDW) produced in Brazil. In this sense, tests involving the variation of the main operational parameters of jigging (bed expansion rate, pulsation frequency and jigging time) were carried out aiming to find those which provided the best recycled aggregates quality after processing. Also, fines and dust emissions generation during jigging were measured in order to estimate their potential impacts on human health and environment. The results showed that the air jigging process is adequate to improve the quality of CDW by increasing the concrete concentration in the dense product. The use of high bed expansion rates showed to be of major importance to decrease the content of ceramic aggregates in the dense product, allowing obtaining products richer in concrete. Also, the measured properties of the obtained aggregates (size distribution, shape, etc) met the usual standards required for natural aggregates. Finally, material losses and dust emissions generated were negligible in comparison to the total mass processed, although special attention must be given to safety measures due the presence of inhalable particles (<10 µm).

Usage of air jigging for multi-component separation of construction and demolition waste.

The use of air jigging for performing multi-component separation in the treatment of mixed construction and demolition waste was studied. Sorting tests were carried out with mixtures of equal bulk volume of concrete and brick in which fixed quantities of unwanted materials - gypsum, wood and paper - were added. Experimental results have demonstrated the possibility to use air jigging to carry out both the removal of low-density contaminants and the concrete concentration in only one process step. In relation to the removal of contaminants only, the overall performance of jigging process can be comparable with that of commercial air classifiers and automatic sorting systems. Also, the initial content of contaminants seems does not have a significant effect on the separation extent. These results are of particular importance for recycling plants processing as they represent an alternative to optimize the use of air jigs. Further investigation is needed in order to evaluate the practical feasibility of such method.