Dissolution Characteristics of Calcium-Based Alkaline Industrial Wastes

概要

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A pH-stat method for measuring the dissolution rates of calcium-based alkaline industrial wastes (CAIW) in flue gas desulfurization is applied in this paper. The dissolution characteristics of two kinds of CAIW including carbide slag (CS) and magnesium slag (MS) were studied in a stirred tank at 30, 40 and 50°C, pH values of 4.3, 5.4, 6.0 and 7.5, particle sizes of 0.000–0.097, 0.097–0.105 and 0.105–0.3 mm and stirring speed of 300 rpm. The dissolution rate control step of CAIW was analyzed by using a modified shrinking core model. It was found that CS dissolution kinetics followed the film diffusion accompanied by surface reaction control, and the activation energies of the two steps were 7.89±1.0 kJ mol−1 and 14.41±1.0 kJ mol−1, respectively. The MS dissolution obeyed the surface reaction model and the activation energy was 14.51±0.5 kJ mol−1.