To clearly elucidate the oxidative roasting behaviors of the bastnaesite, the thermal decomposition and oxidation of the bastnaesite concentrate in inert and oxidative atmosphere have been investigated in detail. Expe...To clearly elucidate the oxidative roasting behaviors of the bastnaesite, the thermal decomposition and oxidation of the bastnaesite concentrate in inert and oxidative atmosphere have been investigated in detail. Experimental data indicated that the initial decomposition temperature of the concentrate under N2 atmosphere is 150 ℃ higher than that under O2 atmosphere,most likely because the oxidation of the cerium induces the decomposition of the concentrate. For the roasted samples under N2 atmosphere at500 ℃ and above,the oxidation efficiency of the cerium is 19.8%-26.8% because of the fact that rareearth fluorocarbonate is first decomposed to form rare-earth oxyfluoride and CO2, and the cerium oxyfluoride is then partially oxidized by the CO2 gas. The rest cerium in these samples can be further oxidized in air at room temperature, with the oxidation efficiency of the cerium gradually increasing to above 80% in 7 d. This can be attributed to the obvious changes in the inner morphology of the roasted samples under N2 atmosphere at high temperatures, which largely induce the diffusion of the air and improves the oxidation activity of CeOF, and further induces the oxidation of CeOF by the air. XRD and XPS techniques were used to further verify the significant differences in the thermal decomposition behaviors of the bastnaesite concentrate under N2 and O2 atmosphere. Moreover, no oxidation of Pr^（3＋） to Pr^（4＋） in the roasted samples under both N2 and O2 atmosphere is observed. This gives an overall understanding of the oxidative roasting of the bastnaesite concentrate without additives.展开更多
The properties of rare earth partitioning in Chinese industrial rare earth ores were analyzed. Rare earth ores can be divided into the single-mineral type ore with bastnaesite, the multi-mineral type ore with bastnaes...The properties of rare earth partitioning in Chinese industrial rare earth ores were analyzed. Rare earth ores can be divided into the single-mineral type ore with bastnaesite, the multi-mineral type ore with bastnaesite and monazite, and the weathering crust type. Both the Bayan Obo rate earth ore and the Zhushan rate earth ore are a kind of mixed ore, consisting of basmaesite and monazite. Their rate earth partifionings are strongly enriched in light rate earths, where CeO2 is 50% and the light rate earth partitioning is totally over 95%. The Mianning rate earth ore as well as the Weishan rate earth is a kind of rate earth ore only having basmaesite. Their rare earth partitionings are also strongly enriched in light rate earths, in which CeO2 is 47% and the light rare earth partitioning is totally over 94%. For the weathering crust type rate earth ore, there are the Longnan rare earth ore, the Xunwu rare earth ore, and the middle yttrium and rich europium ore. In the Longnan rate earth ore, which is strongly enriched in heavy rate earths, Y2O3 is 64.83%, and the heavy and light rate earth partitionings are 89.40% and 10.53%, respectively. In the Xunwu rate earth ore, which is strongly enriched in light rate earths, CeO2 is 47.16%, and the light rate earth partitioning is totally 93.25%. Y and Eu are enriched in the middle yttrium and rich europium ore. Its middle rare earth partitioning is totally over 10%, and Eu2O3 and Y2O3 are over 0.5% and 20%, respectively, which are mainly industrial resources of the middle and the heavy rare earths.展开更多
基金supported by the National Natural Science Foundation of China(51404035)Beijing Nova program(Z161100004916108)
文摘To clearly elucidate the oxidative roasting behaviors of the bastnaesite, the thermal decomposition and oxidation of the bastnaesite concentrate in inert and oxidative atmosphere have been investigated in detail. Experimental data indicated that the initial decomposition temperature of the concentrate under N2 atmosphere is 150 ℃ higher than that under O2 atmosphere,most likely because the oxidation of the cerium induces the decomposition of the concentrate. For the roasted samples under N2 atmosphere at500 ℃ and above,the oxidation efficiency of the cerium is 19.8%-26.8% because of the fact that rareearth fluorocarbonate is first decomposed to form rare-earth oxyfluoride and CO2, and the cerium oxyfluoride is then partially oxidized by the CO2 gas. The rest cerium in these samples can be further oxidized in air at room temperature, with the oxidation efficiency of the cerium gradually increasing to above 80% in 7 d. This can be attributed to the obvious changes in the inner morphology of the roasted samples under N2 atmosphere at high temperatures, which largely induce the diffusion of the air and improves the oxidation activity of CeOF, and further induces the oxidation of CeOF by the air. XRD and XPS techniques were used to further verify the significant differences in the thermal decomposition behaviors of the bastnaesite concentrate under N2 and O2 atmosphere. Moreover, no oxidation of Pr^（3＋） to Pr^（4＋） in the roasted samples under both N2 and O2 atmosphere is observed. This gives an overall understanding of the oxidative roasting of the bastnaesite concentrate without additives.
基金This work is financially supported by the National Natural Science Foundation of China (No. 50474022).
文摘The properties of rare earth partitioning in Chinese industrial rare earth ores were analyzed. Rare earth ores can be divided into the single-mineral type ore with bastnaesite, the multi-mineral type ore with bastnaesite and monazite, and the weathering crust type. Both the Bayan Obo rate earth ore and the Zhushan rate earth ore are a kind of mixed ore, consisting of basmaesite and monazite. Their rate earth partifionings are strongly enriched in light rate earths, where CeO2 is 50% and the light rate earth partitioning is totally over 95%. The Mianning rate earth ore as well as the Weishan rate earth is a kind of rate earth ore only having basmaesite. Their rare earth partitionings are also strongly enriched in light rate earths, in which CeO2 is 47% and the light rare earth partitioning is totally over 94%. For the weathering crust type rate earth ore, there are the Longnan rare earth ore, the Xunwu rare earth ore, and the middle yttrium and rich europium ore. In the Longnan rate earth ore, which is strongly enriched in heavy rate earths, Y2O3 is 64.83%, and the heavy and light rate earth partitionings are 89.40% and 10.53%, respectively. In the Xunwu rate earth ore, which is strongly enriched in light rate earths, CeO2 is 47.16%, and the light rate earth partitioning is totally 93.25%. Y and Eu are enriched in the middle yttrium and rich europium ore. Its middle rare earth partitioning is totally over 10%, and Eu2O3 and Y2O3 are over 0.5% and 20%, respectively, which are mainly industrial resources of the middle and the heavy rare earths.
