A Study of Reusing EAF Tin-making Slags as Aggregates for Producing CLSM

• Main Authors: Ding-Shun Lin, 林鼎舜
• Other Authors: Ming-Sheng Ko
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/32j8n5

碩士 === 國立臺北科技大學 === 資源工程研究所 === 105 === In this study, the physical, engineering, chemical and leaching characteristics of the slag produced in the process of electric arc furnace tin-making were analyzed to evaluate the feasibility and environmental compatibility of EAF Tin-making slag as fine and coarse aggregates for producing CLSM. Then the CLSM production parameters were designed according to Taguchi experimental design method, and the CLSM specimen was further fabricated. The control variables have three groups and each variable has three levels, including the ratio of coarse to fine aggregates (1: 3, 1: 4, 1: 5), fine aggregates replacement ratio (20%, 30%, 40%) and cement content (200 kg/m3, 250 kg/m3, 300 kg/m3). Finally, the S/N ratio, the variance analysis and the response surface methodology were used to evaluate the performance of CLSM made by replacing the natural aggregates with EAF Tin-making slags. The results show that the EAF Tin-making slags are mainly composed of calcium, silicon, aluminum and iron oxides and the f-CaO content of the composition is only 0.46% ~ 0.57%. The results of the test for potential expansion of aggregates from hydration reactions means that EAF Tin-making slags should not have the potential of expansion. The results of XRD and SEM analysis show that there are mainly calcium fluoride (CaF2) and cuspidine (Ca4Si2O7F2) in the EAF Tin-making slags.The result of JIS K0058-2 shows that Pb in EAF Tin-making slags was slightly higher than the specification standard of Japan, but the result of TCLP analysis was in accordance with the specification standard. And long-term leaching process including column test and tank test, the analysis results shows that the leachability of heavy metals in EAF Tin-making slags do not obviously occur. According to the results of S/N analysis and variance analysis, the order of three factors for influencing the performance of EAF Tin-making slags used as aggreagates of CLSM was：cement content (B) > ratio of coarse to fine aggregates (A) > fine aggregates replacement ratio (C). The results of response surface methodology show that the optimum level of the composite variables is ratio of coarse to fine aggregates 1: 3, the cement content 300 kg/m3, and the fine aggregates replacement ratio 40%. If according to the specification requirements of CLSM, the higher ratio of fine aggreagate replacement and the lower cement content in factor combination number 7 could be the best operating parameters. Based on and the above results, most factor combinations can achieve 20 ~ 90 kgf / cm2 of CLSM specification requirements.