The extraction of niobium and rare earths from niobium concentrate by concentrated sulfuric acid low-temperature roasting-water leaching process was studied. The effects of sulfuric acid dosage, calcination temperature, calcination time, liquid volume to solid mass ratio of water leaching, water leaching time and water leaching temperature on the leaching rates of niobium and rare earths were investigated. The results show that under the optimized conditions of 120% sulfuric acid dosage, calcination temperature of 180 ℃, calcination time of 4 h, liquid volume to solid mass ratio of water leaching of 4∶1, water leaching time of 4 h and water leaching temperature of 25 ℃, the niobium leaching rate is 91.4% and the rare earth leaching rate is 93.9%. The process can achieve efficient extraction of niobium and rare earths from niobium concentrate.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |