Novel Centrifugal Extraction-stripping Process-Treating Spent Etchant From Printed Circuit Board Industry Environmentally Friendly

Material progress is often accompanied by environmental contamination and the depletion of natural resources. As these impacts become more serious, traditional methods of waste disposal are being reevaluated and more environmentally friendly approaches are being adopted.As recycling becomes an economically viable option for an increasing number of contaminants, solvent extraction is becoming an important unit-operation because of its high efficiency and relative low cost. The development of a new solvent extraction process named centrifugal extraction-stripping combine process is the subject of this dissertation. A statistically designed theoretical model was used to describe the behavior of the important process variables prior to demonstrating the approach using high-speed centrifugal extractor and actual waste solutions .Because, in this process, the organic phase circulates freely between the extraction and stripping sections, the two steps are closely related. The resulting large organic/aqueous phase ratio is responsible for the equipment's high efficiency and capacity. The process therefore has potential for efficiently recovering recyclable components at a relatively low cost.The investigation was based on etching solution from the printed circuit-board industry which contains about 160 grams/liter copper. Theoretical kinetic study was carried out on Lix54-100, a commercially available diketone extractant manufactured by HENKEL company. A orthogonal experimental design was used to evaluate the behavior of each factor effecting the extraction efficiency. Based on these results, the optimum set of operating conditions to confirm the results.With feed rates of 2.5ml 'min'1, extraction ratios as high as 57.7% with raffinate Cu concentrations of 67.9g ? L1 were observed. When stripped using sulfuric acid , aqueous Cu concentrations of 52.0 g ? I/1 were obtained - high enough that the Cu could be recovered by either electroplating as metal copper or by precipitation as copper sulfate. The capacity of the experimental apparatus was 180ml;however, a Dalian separation technique center, model YL-3 centrifugal extractor of similar design, could meet the demands of a mid-sized printed circuit board factory.