구연산착화합물 형성에 의한 분별침전법을 이용한 희토류원소의 분리

김동수; 김근배

HWAHAK KONGHAK, Vol.35, No.3, 352-359, June, 1997

Export Citation

구연산착화합물 형성에 의한 분별침전법을 이용한 희토류원소의 분리

Separation of Rare Earth Elements by Fractional Precipitation Method Using Citric Acid as Complexing Agent

김동수, 김근배

초록

희토류원소(La-Nd)의 분별침전에 의한 분리에 있어 구연산을 착제로 사용하여 희토류원소와 안정한 착물을 형성한 후 이에 인산염을 첨가하였을 때의 각각에 대한 반응성 및 혼합물에 대한 분리성과를 조사하였다. 희토류원소-구연산 착물은 pH 9이상의 영역에서 안정한 착물이 형성됨을 알았으며, 이 영역에서 인산에 의한 침전속도는 La-Nd간의 현격한 차이가 생김을 알 수 있었다. 침전속도는 반응물의 농도와 pH에 크게 영향을 받으며, 시간에 따라서도 달라짐이 관찰되었다. La-Nd 이원혼합물의 효율적 분리에 요하는 최적조건은 희토류원소의 초기농도를 0.02 M로 하였을 때, 반응물인 희토류원소, 구연산, 인산염의 초기 혼합몰비가 1：3：1 이고, 용액의 초기 pH를 10으로 하는 것이며 반응시간에 따라 최종 분리산물의 순도 및 회수율을 조정할 수 있음을 발견하였다.

A new method of separation by fractional precipitation of lanthanide mixture is described. The process exploits differential precipitation rate of lanthanide hydroxyl citrate complexes by mono hydrogen phosphate. The complex was stable at a range of pH greater than 9. The differential rate of precipitation between La and Nd was influenced by the initial molar ratio, Ln : C₆H₅O₇^3- : HPO₄^2-. and pH. The rate of precipitation of all the components varied according to the time of reaction, however the rate for La was much faster in the initial stage that it enabled its complete precipitation within 10minutes, leaving large fraction of Nd in solution unaffected. Various ways of separation schemes can be designed by adjustment of the reaction time according to the emphasis on the grade and recovery of the products.

Keywords:Rare Earth;Fractional Precipitation;Citric Acid;Complexing Agent

[References]

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[1] Mark HF, Othmer DF, Overberger CG, Seaborg GT, "Encyclopedia of Chemical Technology," Interscience Publishers, New York, 7, 143 (1968)

[2] Ryoich Y, "Newer Metal Industry," Association of New Metals, Tokyo, 33 (1988)

[3] Mellor T, "The Chemistry of the Lanthanides," Pergamon Press, London, 1 (1975)

[4] Huhery JE, "Inorganic Chemistry," Harper & Row Publishers, New York, 797 (1983)

[5] Spencer JF, "The Metals of the Rare Earths," Longmans, New York, 21 (1970)

[6] Kim YS, Ph.D. Dissertation, Univ. of London, London, England, 10 (1969)

[7] Yost DM, Russel H, Garner CG, "The Rare Earth Elements and Their Compounds," John Wiley and Sons, New York, 39 (1950)

[8] Mellor JW, "A Comprehensive Treatise on Inorganic and Theoretical Chemistry," Longmans, New York, 7, 556 (1924)

[9] Svoronos DR, Boulhassa S, Gillaumont R, Quarton M, J. Inorg. Nucl. Chem., 43, 1541 (1981)

[10] Skorik NA, Kumok VK, Perror EL, Augustan KP, Sevebrennikov VV, Russ. J. Inorg. Chem., 10, 351 (1965)

[11] Rosenqvist T, "Principles of Extractive Metallurgy," McGraw-Hill, New York, 199 (1974)

[12] Skoog DA, West DM, Holler FJ, "Fundamentals of Analytical Chemistry," Saunders Publishers, New York, 64 (1988)

[13] Kolthoff IM, Sandal EB, Meehan EJ, Bruckenstein S, "Quantitative Chemical Analysis," The Macmillan Co., New York, 1150 (1969)

[14] Bassett J, Denney RC, Jeffery GH, Mandham J, "Textbook of Quantitative Inorganic Analysis," Longmans, New York, 499 (1978)