Elucidation of hemihydrate gypsum conversion mechanism of waste gypsum derived dihydrate gypsum

2018 Fiscal Year Final Research Report

• Project/Area Number: 15K05816
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Fluid engineering
• Research Institution: Oita National College of Technology
• Principal Investigator: Ogata Koichiro 大分工業高等専門学校, 機械工学科, 准教授 (50370028)
• Co-Investigator(Kenkyū-buntansha): 佐野 博昭 大分工業高等専門学校, 都市・環境工学科, 教授 (50187275)
• Project Period (FY): 2015-04-01 – 2019-03-31
• Keywords: 廃石膏ボード / 二水石膏 / 半水石膏 / 加熱脱水 / 熱流束

Outline of Final Research Achievements

This study experimentally and theoretically investigated heating mechanism to transferring from dihydrate gypsum to hemihydrate gypsum that produced from waste plasterboard. As the result, it confirmed heating permeation test has an effectivity to evaluation of transferring gypsum particle. It is found the flow of heating air promote to become hemihydrate gypsum by comparison of constant temperature drying oven test and heating permeation test. It revealed experimentally and theoretically that particle Reynolds number, effective thermal conductivity and heat flux are strongly affecting drying properties of gypsum when dihydrate gypsum was heating at flow of air. Furthermore, it was confirm that free water and crystal water of dihydrate gypsum dehydrated and converted to hemihydrate gypsum based on analysis of temperature change of particle bed of dihydrate gypsum. In addition, the reclaim application of waste gypsum and the measuring method of water content examined.

Free Research Field

流体力学

Academic Significance and Societal Importance of the Research Achievements

本研究で対象とした廃石膏ボード由来二水石膏は加熱すると半水石膏および無水石膏に変化する．半水石膏は加水すると固化する性質を持ち，土壌改良剤などと混合する固化材としての有効利用が期待されている．このため，本研究で得られた二水石膏が半水石膏へ転換する加熱脱水メカニズムの知見は学術的に重要である．さらに廃石膏ボードの加熱装置開発や石膏の有効利用へ繋げることが期待でき，工業的意義および社会的意義があるといえる．