Characteristic analysis and reuse potential assessment of the steel-making desulfurization slag

• Main Authors: Yong-siang Liang, 梁詠祥
• Other Authors: Chih-ming Kao
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/81342010523866506794

碩士 === 國立中山大學 === 環境工程研究所 === 100 === Furnace slag is the by-product from steel making process. Desulfurization slag (DS) was produced from the desulphurization process of molten irons in high temperature furnaces processes. DS is heterogeneous oxide materials which are compounded by some main oxides such as SiO2, FeO, CaO, SiO2, MnO, Al2O3, and MgO due to their mass percentage. Because DS has high pH characteristics (12.5), this limits its recycle and reuse. The objective of this study was to evaluate the potential of applying DS as the construction materials or amendments in the aquacultural industry to improve the aqualcultural water quality in the fish farm. The basic characteristic analyses show that the major chemical compositions of powder DS were CaO, SiO2, Fe2O3 and Al2O3. The major crystalline phase composed of SiO2, Ca(OH)2 and CaCO3. Results of DS release test show that when DS could increase pH and alkalinity value in water. Results of micro-structure analysis of powder DS surface showed there were many non-porous materials and heavy metals on DS. Results from the nutrient removal tests show that the ammonia nitrogen adsorption capacity were 0.036 mg/L and 0.069 mg/L when the initial concentration were 10 mg/L and 30 mg/L, respectively. Results form the adsorption model validation test indicate that the adsorption phenomena could fit in Langmuir model. The adsorption capacities of phosphate were 26.4 mg/L and 76.6 mg/L when the initial phosphate concentrations were 10 mg/L and 30 mg/L, respectively. The calculated values of thermodynamic parameters show that the adsorption reaction for ammonia nitrogen was endothermic non-spontaneous process, and the adsorption reaction for phosphate was exothermic spontaneous process. However, the enthalpy change (ΔH) showed that adsorption reaction of DS for ammonia nitrogen was physical adsorption, and the adsorption reaction for phosphate was chemical sorption. In the algae culture experiment, results show that when 25 mg/L of DS was supplied, the growth rate of Chlorella sp. could be enhanced. Thus, the powder DS could enhance the growth of Chlorella sp. A field study using a fish farm as the study site was conducted to evaluate the impact of DS on fish farm water quality when DS was applied as the filling and construction materials of the fish farm. Results show that addition of DS had no significant effect on groundwater and pond water quality. Results from the organic matter analysis of the pond water using EEFM show that humus-like and soluble microbial product (SMP) materials were detected. The dominant algae in the pond water included Scenedesmus sp. and Chlorella sp. indicating the pond water quality was in good conditions. Addition of DS would increase of water alkalinity preventing the acidification of pond water due to the fish feed and fish excreta. Results of heavy metal analysis of soil, groundwater, and pond water complied with the relevant environmental standards. Results of this study will aid in understanding the characteristics of DS and the results will be useful in designing a DS reuse system to achieve the zero waste and resource reuse goal.