Leaching efficiency of copper from industrial sludge with traditional acid extraction (TAE) and microwave assisted treatment (MAT).

In this study various leaching technologies were applied to extract heavy metals from sludge from the printed circuit board process. These methods included traditional acid extraction (TAE) and microwave assisted treatment (MAT). The target heavy metal was copper. Experiments were performed to determine the acid the leaching efficiency by changing operating conditions, including acid type and concentration, leaching time, microwave power, and solid to liquid ratio (S/L). The TAE method demonstrated that copper leaching from a sludge of fine particle sizes (d < 150 microm) was 74% efficient at an S/L of 1/6, a leaching time of 18 hr, using nitric acid in the leaching solution. Then, when the microwave powers were 800 W and 400 W; the leaching time was 30 mins, and the coarse particle size (d < 9.5 mm) was by 1 N sulfuric acid, the copper leaching effects were 93% and 77%, respectively. The MAT procedure reduced the leaching time and improved the leaching efficiency above that obtained by TAE.