combustion of Municipal Solid Waste (MSW) varies with countries and carbonation of IBA can locally represent the sequestration of a small fraction of
emitted CO 2 .
Table 6.5 presents the average Ca, Mg abundance in the materials discussed in
this DI6.2, together with other components.
It is, thus, evident that the materials, either natural or man-made, that can
sequestrate CO 2 are quite complex and, thus, require complex processes for CO 2
fixation, as reported in following paragraphs.
Serpentine is the best source of Mg, while wollastonite, steel slag, cement waste,
and IBA are the most suited sources of Ca.
The processes for mineral carbonation can be categorized as (a) three-phase gas–
liquid–solid direct process and (b) liquid phase chemically driven carbonation. Any
combination of these approaches is also possible for increasing the conversion
yield.
(a) The “Pressure” process works at a temperature of 100–185 °C and a pressure
of 4–15 MPa, depending on the materials used (see Table 6.6) and consists of
an injection of CO 2 and water vapor with other chemicals, into an autoclave
containing the solid crushed and dried material.
Table 6.5 Average composition of natural (serpentine, wollastonite) and industrial materials that
can supply Ca or Mg oxides for mineral carbonation. Figures represent w/w%
Serpentine
Wollastonite
Steel slag
Cement
waste
Incineration
bottom ash
CaO
5
40–50
45–55
60–70
45–55
MgO
35–45
Minor
4.5
2
2.5
Al 2 O 3
5
0.5
2.5
5
5
SiO 2
40
50
18
20
12
Fe 2 O 3
10
Minor
2
2.5
10
Other
components
Cr, Mn,
Ni, others
K, Mn, Ti,
P, others
Mn, Ti, S,
others
K, P, Ti,
Mn, others
Na, P, S, Cl,
K, others
Table 6.6 Response of various materials to the direct carbonation in a three-phase process
Material
T (°
C)
P CO2
(MPa)
Other additives
Conversion yield
%
Olivine
185
15
NaCl, 1 M, NaHCO 3 ,
0.64 M
ca. 80–92%
Wollastonite
100
4
Neat
ca. 80+%
Serpentine
155
11.5
NaCl, 1 M, NaHCO 3 ,
0.64 M
ca. 80+%
Lizardite
150
10–15
NaCl, 1 M, NaHCO 3 ,
0.64 M
ca. 36%
6.7 Fixation of CO 2 into Long-Lasting Inorganic Materials
95
emitted CO 2 .
Table 6.5 presents the average Ca, Mg abundance in the materials discussed in
this DI6.2, together with other components.
It is, thus, evident that the materials, either natural or man-made, that can
sequestrate CO 2 are quite complex and, thus, require complex processes for CO 2
fixation, as reported in following paragraphs.
Serpentine is the best source of Mg, while wollastonite, steel slag, cement waste,
and IBA are the most suited sources of Ca.
The processes for mineral carbonation can be categorized as (a) three-phase gas–
liquid–solid direct process and (b) liquid phase chemically driven carbonation. Any
combination of these approaches is also possible for increasing the conversion
yield.
(a) The “Pressure” process works at a temperature of 100–185 °C and a pressure
of 4–15 MPa, depending on the materials used (see Table 6.6) and consists of
an injection of CO 2 and water vapor with other chemicals, into an autoclave
containing the solid crushed and dried material.
Table 6.5 Average composition of natural (serpentine, wollastonite) and industrial materials that
can supply Ca or Mg oxides for mineral carbonation. Figures represent w/w%
Serpentine
Wollastonite
Steel slag
Cement
waste
Incineration
bottom ash
CaO
5
40–50
45–55
60–70
45–55
MgO
35–45
Minor
4.5
2
2.5
Al 2 O 3
5
0.5
2.5
5
5
SiO 2
40
50
18
20
12
Fe 2 O 3
10
Minor
2
2.5
10
Other
components
Cr, Mn,
Ni, others
K, Mn, Ti,
P, others
Mn, Ti, S,
others
K, P, Ti,
Mn, others
Na, P, S, Cl,
K, others
Table 6.6 Response of various materials to the direct carbonation in a three-phase process
Material
T (°
C)
P CO2
(MPa)
Other additives
Conversion yield
%
Olivine
185
15
NaCl, 1 M, NaHCO 3 ,
0.64 M
ca. 80–92%
Wollastonite
100
4
Neat
ca. 80+%
Serpentine
155
11.5
NaCl, 1 M, NaHCO 3 ,
0.64 M
ca. 80+%
Lizardite
150
10–15
NaCl, 1 M, NaHCO 3 ,
0.64 M
ca. 36%
6.7 Fixation of CO 2 into Long-Lasting Inorganic Materials
95