Application of Ferro Nickel Slag to Soil Improvement Agent

Si dissolution rate and mechanism of the ferro nickel slag with different mixing ratios of scallop shell and cooling rates have been investigated to apply ferro nickel slag as soil improvement agent. Slag with slow cooling rate was consisted of crystalline materials such as forsterite and enstatite. On the other hand, the slag with rapid cooling rate was amorphous material. Different constituent crystalline materials were obtained by addition of scallop shell. After addition of 30wt% the scallop shell, Ca-bearing crystalline materials such as monticellite, akermanite, wollastonite and augite were generated in the molten slag. The results obtained by batch dissolution experiment and SEM/EDX observation are summarized as follows. (1) The amorphous slag has a faster Si dissolution rate than crystalline slag. However, Si dissolution rate of the crystalline slag become faster after addition of scallop shell. Si dissolution rate of the molten ferro nickel slag after addition of 30wt% scallop shell has the same with that of the amorphous slag with rapid cooling rate. (2) Ca-bearing crystalline materials such as monticellite, akermanite, wollastonite and augite were easily dissolved than Mg-bearing materials such as forsterite and enstatite which were originally contained in the slag with slow cooling rate. (3) Among the crystalline materials in the slag, dissolution of the part consisted mainly of monticellite were distinguished. It was followed by wollastonite, akermanite and augite. Marked dissolution did not observed in the part consisted mainly of forsterite and enstatite. (4) Difference in dissolution behavior of the crystalline materials was due to the Ca content and degree of silica tetrahedron polymerization. (5) Release of the nutrient elements such as Si and Mg can be promoted by the selection of rapid cooling rate and addition of scallop shell as Ca source in the production of slag.