Evaluation of Crystal of Mg（OH）₂ Using Bittern after Removed Potassium Chloride Given by Sea Salt Manufacturing Process

Abstract

This study aims to collect fundamental data for recovery of Mg resources from RPB. In the experiment, calcium hydroxide（CH）was added to RPB provided by a salt producing company to precipitate magnesium hydroxide（MH）, and the crystals were evaluated. The CH was added to the solution as powder or supersaturated aqueous solution（milk of lime）. It was confirmed that the peak intensity of MH increases as the concentration of RPB from XRD patterns decreases when milk of lime is added. When CH was added as a powder, MH was precipitated independently of the concentration of RPB, and the peak intensity of MH was constant. The shape of the products was observed by SEM. It was confirmed that when added as powder, the particle size becomes relatively larger than when added as milk of lime. The morphology was indicated to be spherical when added as milk of lime, and an irregular shape when added as powder. On the other hand, it was found that decreasing the concentration of RPB to perform the reaction increased the pH after the reaction and increased the yield. Therefore, this study is considered to be useful as fundamental data to develop a recovery process of MH from RPB.