中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 34 No. 1 January 2024 |
（1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2. Key Laboratory of Hunan Province for Metallurgy and Material Processing of Rare Metals, Central South University, Changsha 410083, China;
3. College of Science, Central South University of Forestry and Technology, Changsha 410004, China）
Abstract:β-ammonium tetramolybdate [β-(NH4)2Mo4O13] was prepared in a concentric structure reactor. The species and microstructure of Mo with the change of solution acidity in the preparation process were investigated. The results showed that the pH of the solution should be controlled below 2.5 to obtain ammonium tetramolybdate crystals. In the acidification process, NH3？H2O was used to adjust the pH back to about 3.0 to dissolve the fine crystals produced and facilitate the conversion of ammonium heptadmolybdate to ammonium tetramolybdate. Decreasing the soaking time between the (NH4)4Mo4O12(O2)2？2H2O crystals and the original liquor was beneficial to obtaining β-(NH4)2Mo4O13. Based on the polymerization mechanism of molybdenum, a multi-lattice concentric circle reactor was designed to realize the regional regulation of ammonium molybdate crystallization. High-quality β-(NH4)2Mo4O13 was prepared continually by periodically adding HNO3 solution, ammonia water, and product slurry under specified conditions.
Key words: β-ammonium tetramolybdate; acidification; ionic polymerization; concentric structure reactor
