In the Lombardy Region, an annual production of black slag from electric arc furnace is estimated at around 800,000 tons, mainly from the territory of the province of Brescia. The lack of clarity of technical regulations and the linear mentality still present in the sector made the slag to remain as a not recovered material by-product. For this reason, an exploitation activity for the utilization of slags (as well as inert solid residues) has been carried out with a special focus on civil applications. To this end, data about the slag have been collected and the verification of the chemical behavior of the slag in terms of release has been performed. This has provided a more accurate understanding of the behavior of these materials in the environment with reference to the risks to human health, in particular, the ecotoxicity, mutagenicity and genotoxicity tests.
Moreover, the potential of waste heat recovery for IS applications by taking advantage of the already existing installations and experiences on Brescia territory has been analysed. A specific focus was put on the utilization of residual heat at low temperature, which can be recovered more efficiently for district heating rather than for internal energy needs of the plant. To this end, an updated inventory of the new possibilities of heat recovery has been carried out, exploring the different technological options (as ORC, heat pump and PCMs) and contacting potential suppliers and, as a result, different strategies have been assessed to select the most suitable option and technology.
Therefore, this report has two main sections:
– slags: characteristics, principal uses, leaching tests and ecotoxicity analysis,
– heat recovery: main systems to recover heat, European and Italian situation, examples of heat recovery in the Brescia demo-case.