Preparation of ammonium molybdate by oxidation roasting of molybdenum concentrate: A comparison of microwave roasting and conventional roasting

• Published in: Chemical engineering and processing Vol. 167; p. 108550
• Main Authors: Zhang, Meng-ping, Liu, Chen-hui, Zhu, Xiong-jin, Xiong, Hua-bin, Zhang, Li-bo, Gao, Ji-yun, Liu, Man-hong
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2021
• Subjects: (NH4)6Mo7O24∙4H2O; Conventional roasting; Microwave roasting; Molybdenum concentrate; Molybdenum concentrate; Microwave roasting; (NH4)6Mo7O24∙4H2O; Conventional roasting
• ISSN: 0255-2701; 1873-3204
• DOI: 10.1016/j.cep.2021.108550

•A novel microwave-assisted method for preparing (NH4)6Mo7O24∙4H2O is proposed.•Microwave roasting is more effective and green compared to conventional roasting.•The leaching process of ammonium molybdate is optimized.•The purity of (NH4)6Mo7O24∙4H2O prepared by microwave roasting is higher. A novel and efficient microwave oxidation roasting method for preparing ammonium molybdate from molybdenum concentrate has been proposed and compared with the conventional roasting. TG-DTG, XRD, SEM-EDS, EDX and FTIR methods were used for characterization and analysis of oxidation roasting of ammonium molybdate. Based on the results of thermodynamic and dielectric properties of molybdenum concentrate, the effects of roasting temperature, roasting time, material mass and microwave power density on the oxidation degree of molybdenum concentrate were investigated. The influence of leaching agent, the concentrations of nitric acid and ammonia water on the leaching of ammonium molybdate was investigated. Under the same roasting conditions, the degree of oxidation of molybdenum concentrate by microwave roasting was higher than that of conventional roasting. Microwave roasting reduce the heating time of 30 min to reaction temperature and save 2.0 kW/h power in each roasting experiment. The optimal roasting and leaching conditions are as follows: roasting temperature of 600°C, roasting time of 2 h, power density of 100 W/g, nitric acid concentration of 0.80 mol/L, ammonia concentration of 25%. The purity and crystallinity of (NH4)6Mo7O24∙4H2O prepared by microwave roasting molybdenum concentrate are higher and better stability. [Display omitted]