Recycling of metallic products is one of the important technologies for the formation of a resource-recycling society to reduce carbon dioxide emissions. Because most metal waste is an alloy and it usually consists of various elements, an efficient method to separate these elements from the metal waste is required. Separation of solid and liquid under two phase co-existing condition is one of the promising methods since their chemical components are different. Electromagnetic separation is expected for this purpose because large difference between the solid and the liquid in electrical conductivity induces relatively large difference in the electromagnetic force than that in the gravitational force. Thus, solidification experiment using a low melting point binary Sn-10 mass% Pb alloy under different electromagnetic field imposition conditions has been done, and eutectic ratio adopted as an index of solute separation or segregation was evaluated. Obvious segregation was not observed under a static magnetic field imposition condition because it has a flow suppression function. Segregation was enhanced under the condition of simultaneous imposition of the static magnetic field and an alternating current. The degree of the segregation under the no-electromagnetic field condition was intermediate between those under the magnetic field imposition condition and the simultaneous imposition condition. The eutectic size under the simultaneous imposition condition was larger and this might become easier the liquid motion in the latter stage of the solidification.

The concentration dependence of the activity coefficients of solutes in molten iron is expressed in terms of interaction parameters. The interaction parameters were determined by the experiments under thermodynamic equilibrium and the evaluation had been based only on the accuracy of the experiments. An evaluation of the interaction parameters is proposed due to the thermodynamic stability of homogeneous solution, and is applied to several interaction parameters of the solutes of O, S, Ca and Al in molten iron at 1600°C.

Mortar blocks to heal coastal environments were prepared with cement and fine aggregates composed of steel slag and wood chips. Inorganic and organic species leached from the pulverized mortar blocks prepared in this work. Fe, Si, Mg, Al, Mn, Ca, and S were contained in the leachate as inorganic species. Among them, Fe, Si, Mg, Al, and Mn mainly leached from the steel slag in the mortar block. The elution of these elements was facilitated by the wood chips. Because Ca and S mainly leached from the cement component, the ratio of steel slag and wood chips added to the mortar block gave no effects on the elution of these elements. The leachate of the mortar block also contained not only vanillin and benzoic acid derived from lignin, but also sugar derived from cellulose. These organic substances evolved from the wood chips in the mortar blocks during the preparation process. The steel slag added in the mortar blocks facilitated leaching these organic components. Because the organic and inorganic components feed nutrients to aquatic lives in coastal areas, the prepared mortar blocks could recover damaged coastal environments.