采用碱法烧结-分步浸出法, 对重庆安稳电厂循环流化床粉煤灰中Ga、Nb、REE 等稀有金属进行了联合提取实验。结果表明, 粉煤灰加无水碳酸钠在860℃下烧结30 min, 采用水浸法提取Ga, 采用酸浸法提取REE, Ga、REE 的提取率分别达到84.70%和80.07%;Nb 在两步浸出实验中的浸出率均低于1%, 但在酸浸滤渣中得到富集。采用D201 离子交换树脂和NH4Cl(0.5 mol/L)溶液在40℃下对富Ga 水浸滤液中的Ga 进行吸附与解吸附, Ga 的吸附率(27.99%)、解吸附率(37.33%)偏低, 可能与解吸附液用量不足和水浸滤液中Al 离子竞争吸附有关, 后续将通过改进实验条件提升Ga 的分离提取效果;酸浸液中REE 及酸浸渣中Nb 的分离提取工艺尚需进一步研究。通过上述稀有金属Ga、Nb、REE 的联合提取及后续工作, 可实现安稳电厂粉煤灰的高附加值利用, 有效缓解粉煤灰造成的环境污染。
关键词:
粉煤灰; 稀有金属; 镓; 铌; 稀土; 联合提取
Alkali sintering-multistep leaching experiments are carried out to extract the rare metals Ga, Nb and REE (rare earth elements) from the fly ash in the circulating fluidized bed (CFB) generated from the Anwen Coal-fired Power Plant in Chongqing, Southwest China. It is shown that, the roasting of the CFB fly ash with 1.5 times Na2CO3 under 860℃ for 30 minutes, followed by the water leaching (Solid/Liquid (S/L)=1:10; 90℃; 2 hours) extraction of Ga and the acid leaching (HCl solution, 6 mol/L; S/L= 1:20; 60℃; 2 hours) extraction of REE, can achieve extraction rates of 84.70% and 80.07% for Ga and REE, respectively. The leaching rate of Niobium (Nb) enriched in the acid leaching residue, is lower than 1% in the above two steps. Adsorption and desorption experiments of Gallium from the Ga-rich water leaching filtrate using the D201 ion exchange resin and NH4Cl solution (0.5 mol/L) are carried out both under a temperature of 40℃. The adsorption rate (27.99%) and the desorption rate (37.33%) of Ga are unsatisfactory. The conditions of the follow-up experiments would be adjusted in order to enhance the separation and extraction effect of Ga. The extraction process of Nb from the acid leaching residue and the separation of REE from the acid leaching solution also need to be further studied. With the above combined extraction technology for Ga, Nb, REE and subsequent studies, a high value-added fly ash product is expected. The environmental pollution pressure caused by the Anwen fly ash might be alleviated.
[1] 岳光溪. 循环流化床技术发展与应用[J]. 节能与环保, 2003(12): 3-4. Yue Guangxi. The development of circulating fluidized bed technology and application[J]. Energy Saving and Environmental Protection, 2003 (12): 3-4.
[2] 史培甫. 工业锅炉节能减排应用技术[M]. 北京: 化学工业出版社, 2009. Shi Peifu. Application technology of energy-saving and emission reduction of the industrial boiler[M]. Beijing: Chemical Industry Press, 2009.
[3] 黄从国. 大气污染控制技术[M]. 北京: 化学工业出版社, 2013. Huang Congguo. Air pollution control technology[M]. Beijing: Chemical Industry Press, 2013.
[4] 姚志通, 夏枚生, 叶瑛, 等. 循环流化床锅炉脱硫灰和普通粉煤灰的特性研究[J]. 粉煤灰综合利用, 2010(1): 6-12. Yao Zhitong, Xia Meisheng, Ye Ying, et al. Study on characteristics of CFB desulfurated fly ash and pulverized fly ash[J]. Comprehensive Utilization of Fly Ash, 2010(1): 6-12.
[5] Dai S, Ren D, Chou C L, et al. Geochemistry of trace elements in Chinese coals: A review of abundances, genetic types, impacts on human health, and industrial utilization[J]. International Journal of Coal Geology, 2012, 94(1): 3-21.
[6] Dai S, Wang X, Zhou Y, et al. Chemical and mineralogical compositions of silicic, mafic, and alkali tonsteins in the late Permian coals from the Songzao coalfield, Chongqing, Southwest China[J]. Chemical Geology, 2011, 282(1-2): 29-44.
[7] Linak W P, Wendt J O L. Trace metal transformation mechanisms during coal combustion[J]. Fuel Processing Technology, 1994, 39(1): 173-198.
[8] 赵毅, 赵英. 从粉煤灰中分离镓的实验研究[J]. 华北电力技术, 1998 (1): 35-37. Zhao Yi, Zhao Ying. Experiment study on the separation of gallium from the fly ash[J]. North China Electric Power Technology, 1998(1): 35-37.
[9] 许富军, 许诺真. 三段碳酸化法生产金属镓[J]. 河南化工, 2002(10): 21-22. Xu Fujun, Xu Nuozhen. Production of gallium by the method of three-section carbonation[J]. Henan Chemical Industry, 2002(10): 21-22.
[10] Abisheva Z S, Zagorodnyaya A N. Hydrometallurgy in rare metal production technology in Kazakhstan[J]. Hydrometallurgy, 2002, 63(1): 55-63.
[11] Kumbasar R A, Tutkun O. Separation and concentration of gallium from acidic leach solutions containing various metal ions by emulsion type of liquid membranes using TOPO as mobile carrier[J]. Hydrometallurgy, 2004, 75(1): 111-121.
[12] 胡明清. 边界品位的调整与低品位矿石资源的回收[J]. 采矿技术, 2006, 6(3): 594-596. Hu Mingqing. Recovery and the adjusting of the boundary of low grade ore resources[J]. Mining Technology, 2006, 6(3): 594-596.
[13] 向永生, 何焕学, 张继林. 低品位矿产资源评价问题研究——以金矿资源为例[J]. 地质与勘探, 2008, 44(3): 79-83. Xiang Yongsheng, He Huanxue, Zhang Jilin. Issues on evaluation of the low-grade mineral resources, taking the golden resources for example[J]. Geology and Exploration, 2008, 44(3): 79-83.
[14] 吕理霞. 氧化铝厂镓的回收[J]. 轻金属, 2002(5): 15-17. Lü Lixia. The recovery of gallium from the alumina smelter[J]. Light Metals, 2002(5): 15-17.
[15] 谢访友, 郭朋成. 用离子交换法从拜耳工艺溶液中提取镓的工业实践[J]. 湿法冶金, 2001, 20(2): 66-71. Xie Fangyou, Guo Pengcheng. Extraction process of gallium from Bayer solution by the ion exchange technology[J]. Hydrometallurgy, 2001, 20 (2): 66 -71.
[16] 杨马云, 蔡军.离子交换法回收镓工艺中螯合树脂的研究[J]. 轻金属, 2007(3): 14-16. Yang Mayun, Cai Jun. Study on ion exchange chelating resin in the process of the gallium recovery[J]. Light Metals, 2007(3):14 -16.
[17] 徐君镐, 李菁华. 用Kelex100由高碱度铝酸钠溶液中萃取镓[J]. 稀有金属, 1994, 18(2): 81-86. Xu Junhao, Li Jinghua. Extraction of gallium from the high alkali sodium aluminate solution by Kelex100[J]. Rare Metals, 1994, 18(2): 81-86.
[18] 陈光, 崔崇, 徐锋, 等. 新材料概论[M]. 北京: 国防工业出版社, 2013 (4): 234-235. Chen Guang, Cui Chong, Xu Feng, et al. New material science[M]. Beijing: National Defence Industry Press, 2013(4): 234-235.