Treatment of metallurgical by-products for metal winning and use as construction material

Every year, millions of tons of by-products from the metal producing industry are dumped as waste and this amount is continuously rising. A competence network, involving Montanuniversität Leoben and seven international partners from industry, was formed to treat this topic. The project "COMMBY- Competnce network for the assessment of metal bearing by-products" consists of three areas: characterisation and evaluation, process development and optimisation, as well as the development of an evaluation procedure for secondary resources.

Among other metallurgical by-products, special attention is paid to the slags generated during lead production. After metallurgical treatment for metal winning, the newly produced slag is evaluated for being used as construction material. Contrary to other approaches, in which these are used as cement substitutes, the focus lies on the substitution of sand. One advantage over the use as cement substitute is the larger particle size and the resulting improvement in eluate values. To achieve this, one possibility is to modify the basicity and investigate its effect on the enclosing behaviour of the slag with respect to environmentally critical compounds such as ZnO and PbO. After evaluating the best conditions for slag production, next steps will include the determination of the optimal amount of sand being replaced by slag without negative impact on the mechanical and chemical properties of the concrete.