Keywords:Coal fly ash Coal-fired power plants Trace element leaching Short-term leaching test results of alkaline fly ash from Yenikoy coal-fired power plant were reported in this paper. ASTM D-3987-85 and TCLP-1311 test methods were applied to determine leaching behavior of selected elements namely, Fe, Ca, Cu, Co, Cd, Mn, Ni, Pb Zn, and Cr (VI) at different particle size fractions and test conditions. Chemical, mineralogical and morphological characterizations of ash samples were also performed using chemical, XRD and SEM-EDS analysis methods. The results showed that CaO dominates in the Yenikoy fly ash sample which directly affects the mobility of trace elements by determining the pH of the leaching medium. Higher mobility values of Cd, Co Cu, Pb, Ni and Zn elements were observed for TCLP-1311 procedure. The concentration of these elements in leachates showed a tendency to increase by decreasing particle size. Overall results suggested that the amount of the selected elements in the final leachates of both tests was lower than the limit values of landfill regulations except Cr (VI).

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This paper presents research conducted to model and analyse the peripheral milling of thin titanium plates. Impact tests are performed and the vibration characteristics of a thin titanium plate modelled empirically. The force process is described by a mechanistic model and experimental data are used to determine the model parameters. The particle swarm optimization technique is used to determine the parameters of the plate vibration and force process models, which are combined to create a complete model of the thin titanium plate peripheral milling operation. The models are validated experimentally and excellent agreement is shown between the simulation and experimental results. A process planning scheme for peripheral milling of thin titanium plates is developed and applied. In this scheme integer numbers of widths-of-cut and depths-of-cut are used and the optimal helix angle and feed are computed for each combination of width-of-cut and depth-of-cut. The process planning test case revealed that the optimal material removal rate decreases as the width-of-cut decreases, the optimal helix angle is independent of the width-of-cut, and the optimal feed increases as the width-of-cut decreases. The test case also revealed that the optimal material removal rate is independent of depth-of-cut, the optimal helix angle increases as the depth-of-cut decreases, and the optimal feed increases as the depth-of-cut decreases.

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