Western Oil Shale Has a High Mercury Content
•Up to 5x the amount in western coal per BTU
Goal: Determine the mercury content and disposition in
Western Oil Shale
Funding: Department of Energy – Cooperative Agreement:
DE-FC26-98FT40323, Base Task 2H0
Background
Experimental Design
• Oil Shale, as a mineral, has all of the
potential environmental issues with
processing as other minerals
• Mercury contamination in fuel sources
has become an environmental focus in
recent years
• How do the mercury issues with oil shale
compare to that of coal?
• Oil shale samples were obtained from
Wyoming, Colorado, and Utah
• The shale was milled to a size of 200mesh
• 100-gram samples were heated under an
inert atmosphere – the vapor was
analyzed for mercury concentration
Objectives
• Measure the mercury content of various
western oil shales
• Determine the disposition of the mercury
during thermal processing
• Compare the results to similar data for
coal
Mercury Emissions from Coal and Oil Shale Combustion
Mercury Content Heating Value
(µg/kg)
(Btu/lb)
Mercury
(mg/MM Btu)
PRB Coal
150
9000
7.6
Wyoming Oil
Shale
98
1275
34.9
Utah Oil Shale
80
2521
14.4
Colorado Oil
Shale
59
1741
15.4
The Mercury Vaporizes Quickly When Heated
1000
500
800
400
600
300
400
200
200
100
0
Test Results: 200°C Desorption
Oven Temp (deg C)
Hg Conc (ug/Nm3)
•80% of the Mercury is Removed at 300oC
•Much of the mercury entrains in the vapor phase
0.5
1.0
1.5
2.0
2.5
Test Time (hours)
Hg data
103.6 g
Final Sample Mass
101.4 g
Mass Reduction
3.3 %
Initial Mercury Content 98 µg/kg
0
0.0
Initial Sample Mass
Temp data
Final Mercury Content
72 µg/kg
Mercury Liberated
28 %
100.2 g
Final Sample Mass
96.9 g
Mass Reduction
3.4 %
1000
500
800
400
600
300
400
200
200
100
Initial Mercury Content 98 µg/kg
0
Mercury Liberated
0
0.0
Final Mercury Content 18 µg/kg
Oven Temp (deg C)
Initial Sample Mass
Hg Conc (ug/Nm3)
Test Results: 300°C Desorption
0.5
1.0
1.5
2.0
2.5
3.0
Test Time (hours)
82 %
Hg data
Temp data
500
800
400
600
300
400
200
200
100
0
Oven Temp (deg C)
Hg Conc (ug/Nm3)
Test Results: 450°C Desorption
1000
Initial Sample Mass
101.9 g
Final Sample Mass
93.0 g
Mass Reduction
8.7 %
Initial Mercury Content
98 µg/kg
Final Mercury Content
<10 µg/kg
Mercury Liberated
>91 %
0
0.0
0.5
1.0
1.5
2.0
Test Time (hours)
Hg data
Temp data
There May Be a Solution
Summary: Most of the mercury present in oil shale will be
liberated during thermal processing.
Depending on conditions, the mercury could be released
in multiple chemical states.
There may be an off-the-shelf commercial solution.
•Vapor Phase Oxidized Mercury (Hg2+)
•Sorbent Technologies
•Activated Carbon (Impregnated, Thief Carbon, Activated Char)
•Metal Oxide Ceramics (Cobalt-Alumina, Chromium-Alumina)
•Vapor Phase Reduced Mercury (Hg0)
•Sorbent Technologies
•Amended Silicates
•Aqueous Mercury (Hg2+)
•Water Treatment Technologies
•Chemical Leaching, Precipitation, Amalgamation
•Hydrocarbon Phase Mercury (Hg0)
•Sorbent Technologies
•Amended Silicates