社会・環境
製鋼スラグの完全溶融化とアルカリ溶出挙動
キーワード:
dissolution of alkali,
steelmaking slag,
fly ash,
complete melting of steelmaking slag,
calcium dissolution
2018 年 104 巻 2 号 p. 107-116
詳細
2018 年 104 巻 2 号 p. 107-116
The problems on the alkali dissolution from steelmaking slag sometime occurred in the location of slag recycling. It is important to clarify the alkali dissolution mechanism and develop the method to inhibit an alkali dissolution. There might be many approaches for decreasing the alkali dissolution, the decrease of basicity (CaO/SiO2) is best and easy way for complete melting and inhibition of the alkali dissolution.
In this study, dephosphorization slag was modified by addition of reagent, fly ash (FA) and brown bottle (BB). Basicity was changed from 2.0 to 0.53. Dissolution experiments were carried out according to the condition developed by Kitamura, et al. based on JIS method.
Ca content in dissolution experiment, which analyzed by ICP, was highest compare to Al, Si, Mg, Fe and P. It was found that the relationship between the content of Ca dissolved and modified basicity (C/(S+F)=CaO/(SiO2+FeOx)) showed good correlation.
On the other hand, the pH value was excellent correlation with the content of Ca, although the value of pH saturated around 11 over 20 ppm of Ca. Then, using the relationship of ion product, Kw=[H+][OH–], the equation between Ca and [OH-] was derived. Finally, the following equation successfully calculates the calcium content [Ca2+] ppm dissolved using pH value.
[Ca2+] = 3.0 × 10(pH–10)
