A study of comminution-liberation and floatability of Copper from printed circuit boards (PCBs) scrap

Abstract

Printed circuit boards (PCBs) were collected from obsolete or defective computers that are the largest source of the kind of waste. PCBs are composed of different materials such as polymers, ceramics and metals. The studies are focused on liberation size and floatability behaviour of the valuable metal (copper) in PCBs. PCBs sample were dry crushed and ground down to assemble the criteria of liberation particle size of samples. Then the samples were sieved with the chosen size fraction. Samples were dissolved into aqua regia solution and analyzed with Atomic Absorption Spectroscopy (AAS) to determine the presence of valuable metals in solution that consists in samples. As well, light microscope was used to determine the degree of liberation of copper from PCBs particles. The floatability test was studied using modified Hallimond tube in the alkaline range from about pH 10 to 13. The result showed the copper element is higher than the other elements in PCBs and liberate at particle size ≤300 μm. The floatability tests conducted indicated that the 2-Mercaptobenzothiazole (collector) is better than Potassium n-Amyl Xanthate at pH 10. Xanthate is very good recovering at pH 11-13 depends on kind of frother. As the dosage of the both collector increase, the percentage recovery of Cu also increase. Methyl Isobutyl Carbinol, (MIBC) is more effective than Propylene glycol as frother. This test makes possible to get a better indication of how trends will be translated to a larger scale.