Improved hydration resistance of magnesia by EDTA and ammonium phosphate as additives

Abstract

The control of magnesia (MgO) hydration ratio is a key factor in refractory slurry processing. The volumetric expansion that follows this reaction can result in MgO product cracks as MgO greatly tends to react with water. Thus, the antihydration of MgO is a key concern in refractory suspension processing. The performances of ammonium phosphate (AP) and ethylene diamine tetraacetic acid (EDTA) as antihydration additives were evaluated by using hydration tests, and ionic conductivity, pH, and particle distribution of MgO powders in water and ethanol were used to provide information related to the MgO powder in different liquids. The results showed that the antihydration additives AP and EDTA can inhibit MgO hydration to some extent; however, AP was more effective in preventing volume expansion.

Keywords

• ammonium phosphate
• edta
• hydration
• magnesia