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Kumari, Archana,Panda, Rekha,Jha, Manis Kumar,Lee, Jin Young,Kumar, J. Rajesh,Kumar, Vinay Elsevier 2015 Journal of industrial and engineering chemistry Vol.21 No.-
<P><B>Abstract</B></P> <P>Systematic study for thermal decomposition of monazite to remove phosphate as a valuable product using Na<SUB>2</SUB>CO<SUB>3</SUB> and NaOH roasting processes to validate the TG/DTA studies is reported here. Monazite in 1:1wt. ratio with Na<SUB>2</SUB>CO<SUB>3</SUB> and NaOH requires a temperature of 900°C and 400°C, respectively, for 120min in order to achieve complete conversion of rare earth phosphate into its oxides. The roasted mass was washed, dried and leached in 6M HCl for 2h, pulp density 30g/L at 80°C which results in >90% REMs recovery. Leach liquor generated will be further processed by solvent extraction and precipitation processes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Effective process for separation and recovery of rare earth metals. </LI> <LI> Alkaline thermal treatment under optimized condition is used to dephosphorize monazite. </LI> <LI> 99% phosphate was separated and recovered as value added product of sodium tri-phosphate. </LI> <LI> The oxide of rare earth concentrate was leached in chloride medium to recover high percentage of rare earth metals. </LI> </UL> </P>
Archana Kumari,Rekha Panda,Manis Kumar Jha,이진영,J. Rajesh Kumar,Vinay Kumar 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.21 No.1
Systematic study for thermal decomposition of monazite to remove phosphate as a valuable productusing Na2CO3 and NaOH roasting processes to validate the TG/DTA studies is reported here. Monazite in1:1 wt. ratio with Na2CO3 and NaOH requires a temperature of 900 8C and 400 8C, respectively, for120 min in order to achieve complete conversion of rare earth phosphate into its oxides. The roastedmass was washed, dried and leached in 6 M HCl for 2 h, pulp density 30 g/L at 80 8C which results in>90% REMs recovery. Leach liquor generated will be further processed by solvent extraction andprecipitation processes.
Leaching of rare earth metals (REMs) from Korean monazite concentrate
Rekha Panda,Manis Kumar Jha,이진영,Archana Kumari,Jhumki Hait,Vinay Kumar,J. Rajesh Kumar 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4
Systematic scientific studies for dephosphorization and acid leaching of Korean monazite are reported here. 50% NaOH (w/v) solubilizes 99.99% phosphate, at 170 ℃, 100 g/L pulp density in 4 h. Kinetics of phosphate leaching fitted well with model ‘‘chemical reaction control,’’ i.e. 1 - (1 - X)1/2 = kct, Ea = 58.04 kJ/mol. Further, rare earth hydroxides (REHs) was leached using 6 N HCl at 90 ℃, 60 g/L pulp density for 2 h to recover ~95% REMs. Leach liquor generated can be further processed using solvent extraction/ion exchange techniques. From the pure solutions, metal/salts could be obtained using evaporation, precipitation, etc.