Rare earth oxide production: What are rare earths? Life Cycle Assessment methodology

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Rare earth oxide production: What are rare earths? Life Cycle Assessment methodology
MSc in Environmental Systems Engineering
Aländji BOUORAKIMA
Supervisor: Julia STEGEMANN
Rare earth oxide production:
Assessment of the environmental impacts
in two Chinese mines
UCL Department of Civil, Environmental and Geomatic Engineering, Gower St, London ,WC1E 6BT
What are rare earths?
 Rare earth elements are a group of 17 metals which,
contrary to their name, are not all very rare
Life Cycle Assessment
methodology
Modelling of
 Modelling
of the
the processes
processes (beneficiation,
(beneficiation,
hydrometallurgy and
and refining)
refining)
hydrometallurgy
Inventory of
 Inventory
of every
every input
input and
and output
output (energy,
(energy,
chemicals, wastes)
wastes)
chemicals,
Assessment of
 Assessment
of the
the environmental
environmentalimpacts
impactsaccording
based on
to six
different
categories:
six
different
categories:
Relative abundance of rare earths elements in Earth’s crust (Haxel 2002)
• Global warming • Radioactive waste generation
• Acidification
• Land use
• Eutrophication
• Toxicity in wastewater
Why are rare earths important?
 They are used in several technological applications and
particularly environmental friendly applications such
as:Electric motors for hybrid  Ni-MH batteries

and electric vehicles
 Generators in wind turbine
 Computer hard disks
 Automotive catalysts
(reduction of NOx and CO)




Hydrogen storage devices
Energy saving light bulbs
LEDs and OLEDs
Solid Oxide Fuel Cells
Rare earth oxide production
 In 2010, 97% of the world production came from China
Midpoint indicators
Category
Unit
Bayan Obo
Maoniuping
CO2 emissions
kg of CO2
6,450
5,940
Atmosphere
acidification
kg of SO2eq
124
779
Wastewater
acidification
kg of SO2eq
559
444
Wastewater
eutrophication
kg of H3PO4eq
428
n/a
Radioactivity
discharge
Bq
5.3 10 7
3.7 10 7
Volume used
m
95.4
n/a
Oxalic acid
C2H2O4
35 kg
35 kg
Ammonium
bicarbonate
NH4HCO3
61 kg
-
Ammonium
sulphates
(NH4)2SO4
861 kg
-
-
327 kg
Toxicity discharge
in wastewater
 In China, only Bayan Obo and Maoniuping deposits
produce light rare earth elements (La, Ce, Nd, Pr, Sm)
 They account for 70% of the world rare earth oxide
production
Question: What are the
environmental impacts of
producing rare earth oxides in
Bayan Obo and Maoniuping?
3
Sodium sulphates
Na2SO4
Conclusion
 The midpoint indicators show that considerable
environmental impacts are related to the rare earth
oxide production
 Rare earth production requires a strict waste
management to avoid radioactive or toxic run-offs
 The processes of rare earth oxide production are very
energy-intensive
Reference:
Haxel, G. B., Hedrick, J.B., Orris, G.J. (2002). "Rare earth elements: Critical resources for high technology", U.S. Geological Survey, available at: http://www.rareelementresources.com/i/pdf/fs087-02.pdf Last access: 31/08/2011.

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