氧化钙沉淀硫酸稀土过程中杂质的分布与去除
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摘要
针对离子型稀土矿传统工艺采用碳酸氢铵或草酸沉淀富集稀土过程中产生大量氨氮或草盐废水,严重污染环境的问题,本文提出采用氧化钙和/或碳酸钠沉淀富集低浓度硫酸稀土浸出液中的稀土。研究表明,以碳酸钠为沉淀剂,所得沉淀为碳酸稀土,经焙烧后REO含量可达92%以上;以氧化钙为沉淀剂,所得沉淀为氢氧化稀土,经焙烧后REO含量低于82%。沉淀及焙烧产物的物相分析表明,以氧化钙为沉淀剂,焙烧产物中的硫酸根主要以碱式硫酸稀土的形式存在,表明硫酸根在沉淀过程中进入了氢氧化稀土的晶格。为了在保证沉淀产物稀土纯度的同时,避免高盐废水排放造成环境污染,降低生产成本,进一步采用氧化钙与碳酸钠复合沉淀的方式处理硫酸稀土浸出液,所得沉淀经焙烧后,REO含量可达89%左右,而SO_3含量降至7. 22%,基本满足生产需求,实现了低浓度硫酸稀土浸出液的高效绿色低成本回收。
In order to solve the problems of large amounts of ammonia or oxalate wastewater generated during the precipitation of rare earth using ammonium bicarbonate/oxalic acid in the conventional rare earth enrichment process for the treatment of the ion-absorbed rare earth ore,a new precipitation method using calcium oxide and/or sodium carbonate was developed for the treatment of low concentration rare earth sulfate solution. Experimental data showed that rare earth carbonate formed when sodium carbonate was used as precipitant,and the REO content of the roasted precipitate higher than 92%. While for calcium oxide,rare earth hydroxide was formed and the REO content of the roasted precipitate was lower than 82%. X-ray diffraction( XRD) analyses of the precipitate and the roasted precipitate addressed that sulfate ion existed mainly in the form of basic rare earth sulfates and entered into the crystal lattice of rare earth hydroxide when using calcium oxide as precipitant. Composite precipitation using calcium oxide and sodium carbonate were employed for the treatment of rare earth sulfate solution to improve the purity of rare earth,and avoid the environmental pollution arising from the discharge of high salnity waste water and reduce the production cost. The REO content of the obtained roasted precipitate was 88. 99%,while the SO_3 content decreased to 7. 22%,which could basically meet the requirements for industrial production and ensure low cost recovery of the low concentration rare earth sulfate solution by an efficient and green process.
In order to solve the problems of large amounts of ammonia or oxalate wastewater generated during the precipitation of rare earth using ammonium bicarbonate/oxalic acid in the conventional rare earth enrichment process for the treatment of the ion-absorbed rare earth ore,a new precipitation method using calcium oxide and/or sodium carbonate was developed for the treatment of low concentration rare earth sulfate solution. Experimental data showed that rare earth carbonate formed when sodium carbonate was used as precipitant,and the REO content of the roasted precipitate higher than 92%. While for calcium oxide,rare earth hydroxide was formed and the REO content of the roasted precipitate was lower than 82%. X-ray diffraction( XRD) analyses of the precipitate and the roasted precipitate addressed that sulfate ion existed mainly in the form of basic rare earth sulfates and entered into the crystal lattice of rare earth hydroxide when using calcium oxide as precipitant. Composite precipitation using calcium oxide and sodium carbonate were employed for the treatment of rare earth sulfate solution to improve the purity of rare earth,and avoid the environmental pollution arising from the discharge of high salnity waste water and reduce the production cost. The REO content of the obtained roasted precipitate was 88. 99%,while the SO_3 content decreased to 7. 22%,which could basically meet the requirements for industrial production and ensure low cost recovery of the low concentration rare earth sulfate solution by an efficient and green process.
引文
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[14] Huang X W,Xiao Y F,Feng Z Y,Chen Y Y,Dong J S,Huang L,Wang L S. Complex rare earth compound containing rare earth hydroxide and rare earth carbonate and its preparation method[P]. 201510036591.2,2015.(黄小卫,肖燕飞,冯宗玉,陈迎迎,董金诗,黄莉,王良士.一种含氢氧化稀土和稀土碳酸盐的稀土复合化合物及其制备方法[P].中国专利:201510036591. 2,2015.)
[15] Liang J B,Ma R Z,Geng F X,Ebina Y,Sasaki T.Ln2(OH)4SO4·n H2O(Ln=Pr to Tb; n~2):a new family of layered rare-earth hydroxides rigidly pillared by sulfate ions[J]. Chemistry of Materials,2010,22(21):6001.
[16] Han Z H,Qian Y T,Yang J,Lu G Q. Soft solution processing of cerium hydroxysulfate powders with different morphologies[J],Journal of Materials Chemistry,2003,13:150.
[17] Frost R L,Scholz R,Xi Y F,Lima R M F. Characterization of the sulphate mineral amaranti using infrared,Raman spectroscopy and thermogravimetry[J]. Molecular and Biomolecular Spectroscopy,2013,114:85.
[18] Chi R A,Tian J. Chemical Metallurgy of Weathered Crust Elution-Deposited Rare Earth Ore[M]. Beijing:Science Press,2006. 187.(池汝安,田君.风化壳淋积型稀土矿化工冶金[M].北京:科学出版社,2006. 187.)
[2] Xiao Y F,Wang M,Feng Z Y,Huang X W,Huang L,Long Z Q. Study on preparation of lanthanum oxide powder by carbon dioxide carbonization[J]. Journal of the Chinese Society of Rare Earths,2014,32(2):197.(肖燕飞,王猛,冯宗玉,黄小卫,黄莉,龙志奇.二氧化碳碳化法制备氧化镧粉体研究[J].中国稀土学报,2014,32(2):197.)
[3] Feng Z Y,Huang X W,Wang M,Zhang G C. Progress and trend of green chemistry in extraction and separation of typical rare earth resources[J]. Chinese Journal of Rare Metals,2017,41(5):604.(冯宗玉,黄小卫,王猛,张国成.典型稀土资源提取分离过程的绿色化学进展及趋势[J].稀有金属,2017,41(5):604.)
[4] Qiu X,Chi R A,Xu S M,Zhu G C. Research progress in development of elution-deposited rare earth ore[J]. Metal Mine,2000,293(11):121.(邱欣,池汝安,徐盛明,朱国才.淋积型稀土矿开发研究进展[J].金属矿山, 2000, 293(11):121.)
[5] Xiao Y F,Liu X S,Feng Z Y,Huang X W,Huang L,Chen Y Y,Wu W Y. Role of minerals properties on leaching process of weathered crust elution-deposited rare earth ore[J]. Journal of Rare Earths, 2015, 33(5):545.
[6] Yang X J,Lin A J,Li X L,Wu Y D,Zhou W B,Chen Z H. China's ion-adsorption rare earth resources,mining consequences and preservation[J]. Environmental Development,2013,8:131.
[7] Cai Q Y,Liu Y Z,Guan B C,Wu L,Ge G. Environmental problems and ecological rehabilitation of ion type rare earth minerals in south China[J]. Territory and Natural Resources Study,2013,(5):52.(蔡奇英,刘以珍,管毕财,吴兰,葛刚.南方离子型稀土矿的环境问题及生态重建途径[J].国土与自然资源研究,2013,(5):52.)
[8] Wang R X,Yang Y M,Yang B,Nie H P,Ye X Y,Liao C F,Yu P,Shen W M. An ion-absorption rare earth extraction method[P]. China Patent:201310199034. 3,2013.(王瑞祥,杨幼明,杨斌,聂华平,叶信宇,廖春发,余攀,沈文明.一种离子吸附型稀土提取方法[P].中国专利:201310199034. 3,2013.)
[9] Chi R A,Li Q,Xu Z G,Zhang Z Y,He Z Y. A weathered crust elution-deposited rare earth ore leaching agent and its method for extracting rare earth[P]. China Patent:201310481335. 5,2013.(池汝安,李琼,徐志高,张臻悦,何正艳.一种风化壳淋积型稀土矿浸矿剂及其提取稀土的方法[P].中国:201310481335. 5,2013.)
[10] Xiao Y F,Feng Z Y,Huang X W,Huang L,Chen Y Y,Wang L S,Long Z Q. Recovery of rare earths from weathered crust elution-deposited rare earth ore without ammonia-nitrogen pollution:I. leaching with magnesium sulfate[J]. Hydrometallurgy,2015,153:58.
[11] Xu R G,Zhong H Y,Li Z F. Study on leaching of rare earth by non-ammonium salt of ion-adsorption type rare earth[P]. China Patent:201310424572. 8,2013.(许瑞高,钟化云,李早发.离子吸附型稀土矿非铵盐浸取稀土的工艺[P].中国专利:201310424572. 8,2013.)
[12] Huang X W,Yu Y,Feng Z Y,Zhao N. A method for recovery of rare earth from ionic rare earth ore[P].201010128302. 9,2010.(黄小卫,于瀛,冯宗玉,赵娜.一种从离子型稀土原矿回收稀土的方法[P].中国:201010128302. 9,2010.)
[13] Feng Z Y,Xiao Y F,Huang X W,Chen Y Y,Dong J S,Huang L,Wang L S. A recovery of rare earth from the precipitation in rare earth salt solution method[P].201510036669. 0,2015.(冯宗玉,肖燕飞,黄小卫,陈迎迎,董金诗,黄莉,王良士.一种从稀土盐溶液中沉淀回收稀土的方法[P].中国专利:201510036669. 0,2015.)
[14] Huang X W,Xiao Y F,Feng Z Y,Chen Y Y,Dong J S,Huang L,Wang L S. Complex rare earth compound containing rare earth hydroxide and rare earth carbonate and its preparation method[P]. 201510036591.2,2015.(黄小卫,肖燕飞,冯宗玉,陈迎迎,董金诗,黄莉,王良士.一种含氢氧化稀土和稀土碳酸盐的稀土复合化合物及其制备方法[P].中国专利:201510036591. 2,2015.)
[15] Liang J B,Ma R Z,Geng F X,Ebina Y,Sasaki T.Ln2(OH)4SO4·n H2O(Ln=Pr to Tb; n~2):a new family of layered rare-earth hydroxides rigidly pillared by sulfate ions[J]. Chemistry of Materials,2010,22(21):6001.
[16] Han Z H,Qian Y T,Yang J,Lu G Q. Soft solution processing of cerium hydroxysulfate powders with different morphologies[J],Journal of Materials Chemistry,2003,13:150.
[17] Frost R L,Scholz R,Xi Y F,Lima R M F. Characterization of the sulphate mineral amaranti using infrared,Raman spectroscopy and thermogravimetry[J]. Molecular and Biomolecular Spectroscopy,2013,114:85.
[18] Chi R A,Tian J. Chemical Metallurgy of Weathered Crust Elution-Deposited Rare Earth Ore[M]. Beijing:Science Press,2006. 187.(池汝安,田君.风化壳淋积型稀土矿化工冶金[M].北京:科学出版社,2006. 187.)