**3.1 Sample analysis of PCBs**

It is important to conduct sample analysis before subjecting the crushed samples to the leaching process. The primary sample had followed three size reduction operations, namely crushing, pulverizing, and milling, and the weight fractions obtained at each operation are explained with their corresponding mesh size shown in **Figure 3**. The ultimate purpose of size reduction has been studied previously and data analyzed.

The graphical representation of size analysis shows that the fraction of sample obtained in the sieves with larger mesh sizes has been decreasing when subjected to a sequence of size reduction operations. However, the total weight obtained in the sieves is approximately conserved with a trace of negligible loss. From the sieve analysis data of each operation, the sample obtained from the ball mill has a fraction of weight in the pan that is less than 0.05 mm. Various studies used shredded samples with a size of less than 0.5 mm, which resulted in a high recovery rate of heavy metals [4, 5]. Present research comprises leaching particle sizes of 0.05 mm and 0.1 mm, which is the sample retained just above the pan (**Figures 4** and **5**).
