Material recycling of inorganic slag by wet ball milling

The possibility of material recycling of inorganic slag by wet ball milling with distilled water and an ethylenediaminetetraacetic acid disodium salt dehydrate (EDTA·2Na·2H2O) reagent was investigated. The wet ball milling of the simulated waste slag powder was performed using a ball mill pot and balls in air for 10 - 100 h at room temperature with the rotational speed fixed at 200 rpm. The fractions of CaO and Fe2O3 in the specimens obtained by wet-ball-milling the simulated waste slag powder decreased, that of SiO2 increased, and those of Al2O3 and Na2O hardly changed. These specimens contained 0.1 – 0.8mass% ZrO2. Appropriate solution and time for wet ball milling were 300 ml distilled water and 20 h, respectively. When the wet ball milling of the simulated waste slag powder was performed twice, the fractions of CaO, Al2O3 and Fe2O3 in the specimen obtained after repeated wet ball milling decreased, those of SiO2 and ZrO2 increased and that of Na2O hardly changed in comparison with those in the specimen wet-ball-milled once. The insoluble end product obtained by soaking the specimen wet-ball-milled once in 6M HCl for 20 hours was composed of 98.5mass% SiO2 and 0.6mass% or less other oxides and is usable as glass material.