Amalgam is universally the most used material for dental appliances. It is the result of mixing mercury with a silver-tin alloy. Dental amalgam contains about 50% mercury, 35% silver and 15% tin. Moreover it can contain smaller quantities of other substances such as copper and zinc. Once the mixture has been made, a part of it is used for the restoration. The rest should be considered as dental amalgam waste. Nevertheless these quantities of hardened or hardening amalgam still remain valuable because of their metal content. The recovery of these precious and semi-precious metals has been the aim of a number of investigations. For the recovery of dental amalgam, the extraction of mercury by distillation is the first step. In most of the cases the extraction of the other metals is realized by application of hydrometallurgical techniques [1]. A few years ago a process was developed in which the amalgam waste was transformed into mercury and a dental amalgam alloy, ready for use [2]. In our laboratory, experiments were carried out on the recovery of dental amalgam waste. Similarly to investigations performed in other scientific studies, the extrac-