| Abstract |
| A large amount of sulfuric acid waste is produced in the semiconductor cleaning process, and it is high-purity except hydrogen peroxide content. This study focus on using a neutralization method to treat sulfuric acid waste and producing high-purity gypsum. The byproduct gypsum can be put into use if it meets the particle size required by the gypsum board or cement company. Sulfuric acid waste was reacted with calcium hydroxide(Ca(OH)2) and the effect of pH, mixing, reaction time, and seed addition on the size of gypsum particles were studied. The result of the study indicated that the gypsum particle size can be larger than 40 μm when the pH is maintained above 4. Secondly, the particle size has a tendency to continue to grow after slowly stirring for about one hour as the neutralization was finished. After that, whether it is continuous slow stirring or not, it maintained the size and has no obvious change. In addition, the addition of seeds promote the particle growth obviously and the staged injection produces a seed effect which also increasing the particle size. |
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| Key Words |
| Gypsum, pH, Particle size, Seed, Sulfuric acid |
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