| Project/Area Number |
01550585
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
無機工業化学
|
|---|
| Research Institution | Tohoku University |
|---|
Principal Investigator |
OKUWAKI Akitsugu Tohoku University. Engineering. Professor., 工学部, 教授 (70005320)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
KAWAMURA Kunio Tohoku University. Engineering. Research Associate., 工学部, 助手 (50204772)
SATO Tsuguo Tohoku University. Engineering. Associate Professor., 工学部, 助教授 (90091694)
|
|---|
| Project Period (FY) |
1989 – 1990
|
| Project Status |
Completed (Fiscal Year 1990)
|
| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1990: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 1989: ¥1,700,000 (Direct Cost: ¥1,700,000)
|
|---|
| Keywords | Rare earth ores / Bastnaesite / Molten alkali / NaOH / Cerium concentrate / Ceria / Cerium(IV) oxide / 塩化希土 / 塩化セリウム(皿) / 塩化ランタン / 塩化ネオジム / 塩化プラセオジム |
|---|
| Research Abstract |
New treatment method for rare earth ores has been studied by using molten alkali. Basing on the experimental results. the optimum conditions were found as follows : reaction temperature. 350 ^ﾟC : under atmosphere : ore size. 100 mesh< ; ore/NaOH weight ratio*0.2. reaction time. 0.5 h. After washing of the reaction products obtained under the optimum conditions to remove alkali with water. oxides of lanthanum and other rare earth metals were extracted more selectively than CeO_2 in a 0.5 M HCl leaching below 5 M. The content of CeO_2 in the HCl leaching residue reached to 60 % or higher. This shows that the residue has enough grade as cerium concentrate. The content of CeO_2 would be able to increase. but the yield of cerium concentrate will decrease because of cerium (IV) dissolution. Since the cerium concentrate is composed of fairly homogeneous micro particles of ca. 0.1 mum. It can be used for the abrasives of glass. Etc. On the other hand. Crude rare earth chloride in which lanthanum chloride was the principal constituent as obtained by concentration of the HCl leaching solution.
Additionally. The kinetic study on the reaction indicated that the dissolution process of oxygen into molten alkali was the rate determining step. Therefore. A continuous reactor of rotary kiln is more suitable than a mixing tank reactor.
Based on the results. We have developed a new procedure for leaching rare earth ores. This method can be applied easily for preparation of cerium concentrate and the rare earth chloride mixture at mine sites in China where mixed rare earth ores are abundant.
|
