2021 Volume 107 Issue 1 Pages 92-102
To recover the barren coast or degraded paddy field, the supply of nutrient elements such as Fe is effective. Since steelmaking slag contains various kinds of potent elements, it is expected to be used as an environmental restoration material. The dissolution mechanism of various elements from slag and the influence of surrounding organic matters and microorganisms must be clarified to utilize steelmaking slag in these methods effectively. In this research, the dissolution tests were conducted by using synthesized CaO-SiO2-FeO-Al2O3-P2O5 amorphous slag samples and aqueous solutions containing gluconic acid. Concentration of various elements in the solution, especially Fe, increased by the addition of gluconic acid. To evaluate the effect of gluconic acid on the dissolution behavior quantitatively, the existence forms of various elements in the solution were thermodynamically estimated based on the experimental results. The maximum ratio of chelated iron to total iron was 97%, indicating that the increase in iron concentration by adding gluconic acid was owing to the formation of iron complex ions. On the contrary, concentrations of Ca, showing complex formation ratio low, or Si and P, for which the complex formation has not been reported, also increased by adding the acid. This suggested the existence of elution mechanisms other than complex formation.
