@article{oai:kansai-u.repo.nii.ac.jp:00011343,
 author = {芝田, 隼次 and Shibata, Junji and 野田, 哲 and Noda, Satoru and 真下, 美紀 and Mashimo, Miki},
 issue = {3},
 journal = {資源と素材 : 資源・素材学会誌},
 month = {Mar},
 note = {Urea is decomposed to make carbon dioxide and ammonia in the solution by heating at about 373K. The reaction to produce rare earth carbonates is investigated by mixing urea solution and the organic phase containing rare earths in an open or closed vessel.Chemical and physical properties,such as surface area, thermal decomposition and shape of particles are measured on the precipitation products and the roasted products.In the closed vessel,the reaction takes place under various conditions of urea and nitric acid concentrations with the precipitation rate of around 90%.In the open system,the precipitation rate is lower than that in the closed system.If a suitable combination of urea concentration and nitric acid concentration is selected, it is possible to obtain the precipitation as high as 60% even in the open system.The obtained precipitation products are found to be rare earth carbonate hydrates and to be easily converted to rare earth oxides.},
 pages = {185--189},
 title = {尿素分解法を利用した有機相からの希土類の晶析剥離},
 volume = {110},
 year = {1994}
}