Aqueous leachate from electric furnace slag

In manufacturing manganese and carbon steel in the basic electric are furna ce, 70 to 80 kg of slag per tonne of steel is produced, whereas The grey ca st production results in 30 to 40 kg of slag per tonne of grey cast. Such l arge slag volumes require special care for their disposal at landfills near steel and rolling mills. It is therefore necessary to examine the chemical stability of slag under various conditions. The paper reports examinations of the chemical and phase composition of sla g, as well as the number of anions and cations. The number of anions and ca tions in water eluates was determined in order to define the influence of s uch material on the environment. The phase composition of slag was determin ed by the X-ray diffraction method. Eluated anions (F-, Cl-, NO2-, Br-, NO3 - and SO42-) were determined by ion-chromatographic analysis. Eluated catio ns (Na+, K+, Ca2+ and Mg2+) were established by spectrometric atom absorpti on. Changes in pH, conductivity and chemical composition of water eluates were monitored for 96 hours. The results have shown that the examined slag mater ial could, with regard to its chemical and phase composition, constitute a stable Fe-Mn-Ca silicate material. However, elution of the examined compone nts, along with the change in conductivity and pH value, implies that slag is not chemically inert and that, therefore the problem of slag disposal ha s to be approached paying special attention on its potential impact on the environment.