From a Hazardous Waste to a Commercial Product: Learning Circular Economy in the Chemistry Lab

We are currently facing a change in the production model, moving from the traditional linear model to a model based on circular economy. This new paradigm implies minimization of waste. In this context, this work presents a laboratory practice focused on introducing the concept of circular economy and waste valorization to undergraduate students. The experimental procedure is a simpler adaptation of earlier work by the research group in which metals were recovered from electric arc furnace dust (EAFD) and it is composed of four stages: acid leaching to dissolve the zinc, selective precipitation to eliminate dissolved iron, cementation to recover metals more noble than zinc, and finally obtaining basic zinc carbonate by precipitation. In this way, students can convert a residue into a valuable product while cleaning it, so that it can be reintroduced into the steel-producing process. Fourth year students of the Materials Engineering Degree at the University of Seville (Spain) have successfully performed this laboratory experiment since the 2015–16 academic year. In addition, to evaluate the achievement of the pedagogical objectives, pre- and postlaboratory questionnaires have been carried out in the past two academic years showing that more than 75% of the students improve their answers after performing the laboratory practices.