Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
METHODS FOR RE-USING INDUSTRIAL WASTE FOR CARBON SEQUESTRATION
AND MAGNESIUM-BASED CEMENTS
Technical Field
[0001] This invention relates to the field of cement, and in particular
magnesium-based
cements.
Background
[0002] There is a general desire to reduce anthropogenic sources of carbon
dioxide.
Carbon dioxide is a prominent greenhouse gas that causes climate change. The
global
cement industry is a significant source of carbon dioxide, with the cement
industry
contributing an estimated 7% to anthropogenic sources of carbon dioxide and an
estimated
23% by 2050.
[0003] Portland cement (the most common type of cement) is produced by first
creating
clinker. Portland cement is merely ground clinker with optional additives.
Clinker is created
by feeding raw materials to a kiln. A major constituent of the feed to the
kiln is limestone
(CaCO3). A kiln is typically in the shape of a long cylinder. It is slanted
such that the inlet
side of the kiln is higher than the outlet side of the kiln, and configured to
rotate to move
material from its inlet to its outlet. At the outlet side of the kiln is a
heat source. Because
there is a heat source only on one side of the kiln, there is a temperature
gradient along the
length of the kiln. At a temperature of approximately 1400 -1500 C, the
limestone will
decompose into calcium oxide (CaO) and carbon dioxide (CO2). Subsequent
reactions
sinter (i.e. fuse together without liquefying) the material in the kiln into
clinker, which can
then be ground to create Portland cement.
[0004] By mass, limestone is approximately 50% carbon dioxide, thus a
significant amount
of carbon dioxide is released during the formation of clinker.
[0005] Numerous strategies have been pursued to address the significant
greenhouse gas
(GHG) emissions from cement production. For example, during the hydration of
Portland
cement, calcium hydroxide (Ca(OH)2) is produced. Calcium hydroxide has been
identified
as a possible source of carbonation (capturing carbon dioxide), therefore
reversing
calcination (releasing CO2). Alternative strategies have been to use
supplementary
cementing materials (SCMs) and aggregates that have been treated with CO2 to
offset the
emission intensity of the cement production. Further, as a technique for
addressing the
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GHG emission from cement production, the most costly and robust process is
post-
combustion capture of the outlet gas of the kiln, typically using a scrubber
system (e.g.
amine-based scrubber system) that produces a compressed CO2 gas stream that
must be
transported for storage.
[0006] Another category of cement is made up of magnesium-based cements. There
are
two main types of magnesium based cement: magnesium oxychloride (MOC) and
magnesium oxysulfate (MOS). Magnesium oxychloride cements (MOC's) are an
alternative
to conventional Portland cement. MOC's are formed from the reaction of
magnesium oxide
(MgO) and magnesium chloride (MgCl2). Mixing magnesium oxide, magnesium
chloride,
and water in a 5:1:12 ratio (i.e. 5 parts magnesium oxide to 1 part magnesium
chloride to 12
parts water) and allowing it to cure creates 'phase 5 MOC', with the formula
5Mg(OH)2-MgC12-8H20. Phase 5 MOC has a microscopic needle structure. The
microscopic needle structure gives phase 5 MOC a high degree of structural
integrity.
Magnesium oxysulfate (MOS) is the sulfate analogue of MOC, wherein magnesium
oxide,
magnesium sulfate and water are mixed in a particular ratio to produce MOS
cement. A
third, less-explored magnesium carbonate based cement has been briefly
investigated and
abandoned due to issues around the stability of the overall cementing phase.
[0007] Magnesium oxide is a required constituent of magnesium-based cement.
Currently,
magnesium oxide is predominantly synthesized via a process named 'the dry
process'. The
dry process entails mining magnesite (MgCO3), and calcining it at a
temperature of 650 -
950 C. Calcination of magnesite produces magnesium oxide (MgO) and carbon
dioxide. A
state-of-the-art dry process produces 1.1kgCO2 per kgMg0 (1.1kgCO2eq).
[0008] Magnesium oxide can also be synthesized via a process named 'the wet
process'.
The wet process entails precipitating magnesium hydroxide (Mg(OH)2) from
magnesium
bearing waters, and heating the magnesium hydroxide at a temperature of
approximately
350 C to create magnesium oxide and water. Typically, calcium hydroxide
(Ca(OH)2) or
sodium hydroxide (NaOH) are used to precipitate the magnesium hydroxide, which
results
in a relatively high cost and carbon footprint, when factoring in the energy
requirements for
drying the product.
[0009] Both processes for obtaining magnesium oxide, the dry process and the
wet
process, are highly carbon intensive.
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[0010] There therefore remains a desired to reduce the carbon intensity of
producing
cement and to thereby ameliorate the greenhouse gas contributions of the
cement industry.
[0011] There is also a general need to make use of waste streams from existing
industrial
processes.
[0012] The foregoing examples of the related art and limitations related
thereto are intended
to be illustrative and not exclusive. Other limitations of the related art
will become apparent
to those of skill in the art upon a reading of the specification and a study
of the drawings.
Summary
[0013] The following embodiments and aspects thereof are described and
illustrated in
conjunction with systems, tools and methods which are meant to be exemplary
and
illustrative, not limiting in scope. In various embodiments, one or more of
the above-
described problems have been reduced or eliminated, while other embodiments
are
directed to other improvements.
[0014] One aspect of the invention provides a method of producing cement, the
method
comprising: obtaining a brine, adding a base and magnesium oxide to the brine
to form a
mixture, bubbling a gas through the mixture wherein the gas contains carbon
dioxide,
precipitating calcium carbonate from the mixture, wherein the precipitating
calcium
carbonate results from a reaction of calcium ions in the brine and carbon
dioxide from the
bubbled gas, and allowing the mixture to cure to thereby form cement.
[0015] Another aspect of the invention provides a method of producing cement,
the method
comprising: obtaining a brine, adding a base to the brine to form a mixture,
bubbling a gas
through the mixture wherein the gas contains carbon dioxide, precipitating
calcium
carbonate from the mixture wherein the precipitating calcium carbonate results
from a
reaction of calcium ions in the brine and carbon dioxide from the bubbled gas,
adding
magnesium oxide to the mixture, and allowing the mixture to cure to thereby
form cement.
[0016] Another aspect of the invention provides a method of producing cement,
the method
comprising: obtaining a brine, bubbling a gas through the brine wherein the
gas contains
carbon dioxide, precipitating calcium carbonate from the brine wherein the
precipitating
calcium carbonate results from a reaction of calcium ions in the brine and
carbon dioxide
from the bubbled gas, and allowing the mixture to cure to thereby form cement.
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[0017] Another aspect of the invention provides a method of producing cement,
the method
comprising: obtaining a brine, bubbling a gas through the brine wherein the
gas contains
carbon dioxide, precipitating calcium carbonate from the brine wherein the
precipitating
calcium carbonate results from a reaction of calcium ions in the brine and
carbon dioxide
from the bubbled gas, adding magnesium oxide to the brine to form a mixture,
and allowing
the mixture to cure to thereby form cement.
[0018] The brine may comprise a waste stream from an industrial process. The
waste
stream could from at least one of the production of oil and gas, the
production of potash, the
production of geothermal energy and desalination. In some embodiments, the
brine
comprises a magnesium content of between 10,000ppm and 120,000ppm. In some
embodiments, the brine comprises a calcium content of between 25,000ppm to
125,000ppm. In some embodiments, the brine comprises a sodium content of less
than
150,000ppm.
[0019] The precipitated calcium carbonate may be left in the mixture as a
filler prior to
allowing the mixture to cure.
[0020] The gas may comprises (or consist of) a flue gas from an industrial
process and/or
power generation process. In some embodiments, the flue gas comprises flue gas
from the
synthesis of magnesium oxide. The flue gas may have a carbon dioxide content
of between
400ppm and 150000ppm by concentration.
[0021] The gas may comprise air.
[0022] The base could comprise any one of, or combination of the following:
ammonium
hydroxide, calcium hydroxide, sodium hydroxide, and potassium hydroxide.
[0023] The method may comprise dewatering the mixture prior to curing to
remove
dissolved ions from the mixture.
[0024] The method may comprise adding additional magnesium oxide to the
mixture after
precipitating calcium carbonate therefrom.
[0025] Bubbling the gas through the mixture may comprise bubbling microbubbles
of the
gas through the mixture or bubbling nanobubbles of the gas through the mixture
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[0026] In addition to the exemplary aspects and embodiments described above,
further
aspects and embodiments will become apparent by reference to the drawings and
by study
of the following detailed descriptions.
Brief Description of the Drawings
[0027] Exemplary embodiments are illustrated in referenced figures of the
drawings. It is
intended that the embodiments and figures disclosed herein are to be
considered illustrative
rather than restrictive.
[0028] Figure 1 is a flowchart depicting a method of forming magnesium-based
cement
according to the prior art.
[0029] Figure 2 is a flowchart depicting a method of forming magnesium-based
cement
according to an example embodiment of this invention.
[0030] Figure 3 is a flowchart depicting a method of forming a magnesium-based
cement
according to an example embodiment of this invention.
Description
[0031] Throughout the following description specific details are set forth in
order to provide
a more thorough understanding to persons skilled in the art. However, well
known elements
may not have been shown or described in detail to avoid unnecessarily
obscuring the
disclosure. Accordingly, the description and drawings are to be regarded in an
illustrative,
rather than a restrictive, sense.
[0032] Figure 1 is a flowchart showing a method of forming magnesium-based
cement
(specifically, MOC) according to prior art techniques. Step 11 comprises
acquiring a
concentrated solution containing magnesium chloride. Magnesium chloride is an
ingredient
involved in the creation of MOC cement. Water is also an ingredient for MOC
cement,
hence the aqueous solution of magnesium chloride. Step 12 comprises adding
magnesium
.. oxide to the magnesium chloride solution. Given the expense associated with
acquiring
magnesium oxide, it is preferably added in a stoichiometric ratio to the
magnesium chloride
and water to limit the amount of unreacted magnesium oxide. As mentioned
above, for a
phase 5 MOC (which is the phase of MOC cement with a high level of structural
integrity),
the stoichiometric ratio is 5 parts magnesium oxide to 1 part magnesium
chloride to 12 parts
water. The mixture from step 12 is then allowed to cure per step 13. The
mixture will initially
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have a slurry-like consistency, but upon curing it will solidify. Curing can
take up to 7 days,
though the curing time is variable and is a function of at least (but not
limited to):
temperature, humidity, and shape of the cured mixture (for example, curing the
mixture in a
cube shaped container will result in a faster curing time than curing the
mixture in a
spherical container due to a cube's higher surface area to volume ratio).
[0033] There are at least two disadvantages associated with the prior art
method of forming
cement shown in Figure 1. The first disadvantage is associated with obtaining
a magnesium
chloride solution. Ideally, the magnesium chloride solution obtained in step
11 should have
as high a purity of magnesium chloride as possible. Impurities (such as
calcium ions)
reduce the effectiveness of the curing step 13, as it will limit the extent of
reaction between
magnesium oxide, magnesium chloride, and water. The calcium in solution does
not form a
5 MOC structure and inhibits the growth of structurally strong cements. The
second
disadvantage of the Figure 1 cement formation technique is associated with the
carbon
intensity of forming magnesium oxide. As mentioned above, production of
magnesium oxide
is a highly carbon dioxide intensive process, and the Figure 1 method does not
ameliorate
the carbon intensity of producing cement.
[0034] Though the flowchart in Figure 1 shows the procedure for making
magnesium
oxychloride cement (MOC), an analogous procedure can be followed for making
other types
of magnesium-based cement. For example, if the ion in solution was magnesium
sulfate
rather than magnesium chloride, then magnesium oxysulfate (MOS) would form. As
mentioned above, magnesium oxysulfate (MOS) is another type of magnesium-based
cement.
[0035] Figure 2 depicts a method 20 of forming cement according to an example
embodiment of the invention. Step 21 comprises obtaining a brine. The brine is
preferably
sourced from an industrial process. Ideally the brine is a waste stream from
the production
of oil and gas, potash, desalination, geothermal energy and/or the like. Oil
and gas, potash,
desalination and geothermal energy production all produce brines with high
magnesium
concentrations (in excess of 10,000ppm), and high calcium concentrations (in
excess of
50,000ppm). These waste streams typically contain high amounts of magnesium
and
.. calcium.
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[0036] The magnesium content of the waste stream that makes up the step 21
brine may
be in a range between 10,000ppm and 120,000ppm and, in some embodiments,
between
50,000ppm-75,000ppm. The calcium content of the waste stream that makes up the
brine
may be in a range between 25,000ppm to 125,000ppm and, in some embodiments,
between 25,000ppm to 50,000ppm. In some embodiments, the sodium content of the
waste
stream that makes up the brine may be less than 150,000ppm and, in some
embodiments,
less than 10,000ppm. There may be some sulfate ions in the waste stream. If
this is the
case (i.e. sulphate ions are present), then during the curing step (step 27),
some
magnesium oxysulfate will form.
[0037] Step 22 comprises bubbling a gas through the brine. The gas could be
from a
number of sources, but the step 22 gas preferably contains carbon dioxide. For
example,
the gas could be flue gas, compressed air and/or an emission source from an
industrial
process. Beyond the desirability that there be carbon dioxide, the step 22 gas
could have
any composition and have a wide array of process stream characteristics. For
example, the
step 22 gas could have high particulate contents, and it could also be at high
pressure or
temperature. The step 22 gas can contain moisture, 02, NOx, SOx and
particulate matter
that may either remain entrapped in the final concrete mixture or be passed
through the
reaction mixture.
[0038] The step 22 gas could also be flue gas from the production of magnesium
oxide. As
mentioned above, the production of magnesium oxide releases substantial
amounts of
carbon dioxide. Using flue gas from the production of magnesium oxide would be
particularly advantageous, as the carbon dioxide created during the production
of
magnesium oxide (see step 24 described in more detail below) could be captured
during the
Figure 2 cement formation method 20.
[0039] Bubbling through the gas containing carbon dioxide per step 22 causes
precipitation
of calcium carbonate per step 23. When in basic solution, calcium ions exposed
to carbon
dioxide from the bubbling of CO2-containing gas in step 22 will precipitate
out of solution in
step 23 and form solid calcium carbonate. Other carbonates may also form when
the brine
is exposed to carbon dioxide in step 22 (magnesium carbonate may precipitate
in step 23,
for example), however the predominant carbonate that forms as a precipitate in
step 23 will
be calcium carbonate. The approach is based on the solubility product
differences in the
Ca(OH)2 or Mg(OH)2 which dissociate to Ca2+/Mg2+ and OH- and the availability
of the
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corresponding ions, that then react with C032- to be precipitated as
carbonates. In addition,
the higher hydration energy of Mg2+ (compared to Ca2+), drives Ca-carbonate
precipitation
preferentially under the coexistence of Ca and Mg ions as described, for
example, by Bang
et al. in Journal of CO2 Utilization 33 (2019) 427-433.
[0040] The precipitated calcium carbonate can either remain passively in the
solution and
the final concrete mix as a precipitate or be removed through a filtering
operation (which
would remove the solid calcium carbonate).
[0041] In currently preferred techniques, the gas used to bubble through the
solution in step
22 comprises microbubbles (on the order of 1pm-1000pm in diameter) or
nanobubbles (on
the order of 100nm-1000nm in diameter), which may be generated using a
suitable
microbubble or nanobubble generator. Microbubble and naonbubble generators
create very
small bubbles of a gas in a liquid. Microbubbles and nanobubbles of relatively
small size
may be advantageous as their small size increases the surface area per unit
volume of
each of the bubbles of gas. This relatively large surface area to volume ratio
in turn
increases the extent of carbonation of the ions in the brine, thereby
increasing the amount
of calcium carbonate precipitated out of the brine.
[0042] Bubbling the gas containing carbon dioxide through the brine is
advantageous for at
least two reasons. A first advantage is that bubbling through the gas
sequesters carbon
dioxide in the form of calcium and/or magnesium carbonate, which has a low
solubility in
water. A second advantage is that once solid calcium carbonate is formed, it
can be added
back to (or left in) the mixture prior to or during the curing step (step 27 ¨
explained in more
detail below) as a filler for the magnesium-based concrete.
[0043] After precipitating calcium carbonate, step 24 comprises adding
magnesium oxide to
the mixture. Magnesium oxide is a component of magnesium-based cement.
[0044] Step 25 is an optional step that comprises dewatering the mixture.
Dewatering may
server a number of purposes.
[0045] One purpose of the optional step 25 dewatering process may be to remove
dissolved ions. As mentioned before, the brine may contain ions such as (but
not limited to)
sodium, potassium, or iron. These ions do not normally form part of the
binding phase of
magnesium-based cements. Furthermore, these ions will not precipitate out of
solution to
the same extent as calcium carbonate (e.g. due to the low solubility of
calcium carbonate).
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As such, it may be desirable to remove some of the water from the mixture
prior to curing in
step 27. Removing some of the water may reduce the total amount of dissolved
ions in the
curing step, but the concentration of dissolved ions in solution will remain
the same.
[0046] Another purpose for optional step 25 dewatering process may be to
adjust the ratio
of magnesium oxide, magnesium chloride, and water. As mentioned before, the
constituents of MOC cement are ideally mixed in a ratio of 5 parts magnesium
oxide to 1
part magnesium chloride to 12 parts water, as this will form a phase of MOC
cement that
has high strength. Too much water may cause less desirable MOC cement phases
to form.
These are non-exhaustive purposes for dewatering in optional step 25; there
may be other
purposes for the optional dewatering step 25.
[0047] Step 26 is another optional step that comprises adding solid calcium
carbonate
precipitated in step 23 back to the mixture. After adding magnesium oxide (per
step 24), the
mixture may have a relatively high pH. Calcium carbonate is moderately
insoluble at neutral
pH's (of approximately 7), but calcium carbonate's solubility decreases as a
function of
increasing pH. As such, adding calcium carbonate back to the solution in
optional step 26
after adding magnesium oxide in step 25 will not cause calcium ions to form in
the solution.
Instead, the solid calcium carbonate will form part of the cured
cement/concrete, and may
act as a 'filler' in the cement/concrete. This use of calcium carbonate as
part of the cured
cement/concrete may be advantageous in that it increases the total amount of
carbon
storage capacity of the product obtained from the process, while having a
positive impact on
the binding strength of the cement/concrete.
[0048] Step 27 comprises curing the solution. The time spent curing is a
function of at least
temperature, humidity, and the shape of the curing vessel. In some
implementations, curing
in step 27 may take time in a range of 72hours to 7 days. In some
implementations, curing
in step 27 is performed at a temperature in a range of 20 -50 C, with
currently preferred
temperatures in a range of 20 -30 C. During the step 27 curing process,
humidity may be
maintained relatively high (e.g. above 90%) for a first period of time (e.g.
18-30 hours) and
the humidity may be decreased (e.g. to levels in a range of 50%-80% or to
levels of 50%-
60%) from 30 hours onward for the remainder of the step 27 curing process.
[0049] Figure 3 depicts a method 30 for forming cement according to another
example
embodiment. Method 30 of Figure 3 is similar in many respects to method 20 in
Figure 2,
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except that method 30 involves the extra step of adding base to the solution
prior to
bubbling gas through the brine. As mentioned above, the solubility of calcium
carbonate
decreases with increasing pH. Consequently, adding base to the solution
(increasing the
pH) prior to bubbling CO2-containing gas through the solution may result in
increasing the
amount of calcium ions extracted from the solution (in the form of
precipitated calcium
carbonate) by bubbling CO2-containing gas through the solution.
[0050] Step 31 comprises obtaining a brine. Step 31 may be substantially
similar to step 21
of method 20 (Figure 2) described above. As mentioned above, the brine could
be sourced
from an industrial process. Ideally the brine is a waste stream from the
production of oil and
gas, potash, desalination, geothermal energy and/or the like. There may be
some sulfate
ions in the waste stream. If this is the case, then during the curing step
(step 38), some
magnesium oxysulfate will form.
[0051] Step 32 comprises adding a base to the brine. The base could be any
suitable
compound, or combination of compounds, that increases the pH of the brine,
including, for
example, the following compounds. Such base additives may include, by way of
non-limiting
example, hydroxides (such as sodium hydroxide, calcium hydroxide, or ammonium
hydroxide), natural alkaline mineral sources such as treated zeolite, and/or
the like.
Ammonium hydroxide is particularly advantageous to use in the example
embodiment of
method 30 shown in Figure 3, because ammonium hydroxide will form ammonium
chloride
when in solution. Ammonium chloride is soluble, and will remain in the brine
liquid until the
optional dewatering in step 36. In step 36 (discussed in more detail below),
the brine can be
dewatered to remove excess liquid prior to curing. Since the ammonium chloride
is soluble,
it will be removed in the dewatering step. The ammonium chloride in solution
from the
dewatering step can then be easily converted back into ammonium hydroxide
(e.g. through
the Solvay Process).
[0052] Instead of adding a hydroxide, magnesium oxide itself could be
added to the
brine. Magnesium oxide is advantageous to add because it is desirable as part
of the
binding phase for the concrete. It would be disadvantageous to add magnesium
oxide in
that is far in excess of the stoichiometric ratio associated with phase 5 MOC
(discussed
above), as magnesium oxide is both expensive and carbon intensive to produce
and,
further, excessive magnesium oxide may promote the formation of less desirable
cement
phases if not fully consumed as a base.
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[0053] Furthermore, magnesium oxide in combination with another base
could be
added to the brine to increase the pH of the brine.
[0054] Adding a base to the brine in step 32 is advantageous for at
least the following
reason. Calcium carbonate's solubility decreases as a function of increasing
pH. Increasing
the pH with a base will decrease the concentration of calcium ions in
remaining in solution
after steps 33 and 34 (i.e. increasing the pH of the solution will increase
the amount of
calcium carbonate precipitate caused by bubbling CO2-containing gas through
the solution).
[0055] Step 33 is similar to step 22 of method 20 (Figure 2) described
above and
comprises bubbling a gas through the mixture. As mentioned before, calcium
ions in the
mixture, when exposed to gaseous carbon dioxide, will precipitate out of
solution. Given the
high pH (because of step 32), there will be increased precipitation of calcium
carbonate
from solution due to calcium carbonate's low solubility at high pH. As
mentioned in the
description of method 20 (Figure 2), the bubbling should ideally be done using
microbubbles
and/or nanobubbles which may be produced with a microbubble or nanobubble
generator,
as small size bubbles tend to increase the extent of carbonation of ions
(including, in
particular, carbonation of calcium ions with carbon dioxide to form calcium
carbonate
precipitate) in the brine.
[0056] Step 34 comprises precipitation of the calcium carbonate from the
brine through
the reaction between calcium ions in the brine and carbon dioxide in the gas.
Step 34 may
be similar to step 23 of method 20 (Figure 2) described above.
[0057] Step 35 is an optional step that comprises adding magnesium oxide
to the
mixture. Magnesium oxide is a component which helps to create the binding
phase of MOC
cement. If magnesium oxide was not added as the base in step 32, or if there
is insufficient
magnesium oxide to achieve the stoichiometric ratio desirable for phase 5 MOC,
then step
35 may be used to add additional magnesium oxide (preferably in an amount that
achieves
a stoichiometric ratio of 5 parts magnesium oxide to 1 part magnesium chloride
to 12 parts
water) to the mixture.
[0058] Step 36 is an optional step that comprises adding back solid
calcium carbonate
to the mixture. Optional step 36 may be similar to option step 26 in method 20
(Figure 2). As
described above, calcium carbonate has low solubility at high pH. In some
embodiments,
some or all of the calcium carbonate optionally added back to the mixture in
optional step
36 may be the precipitate obtained from step 34. The calcium carbonate added
in block 36
may act as a filler in the final cement product.
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[0059] Step 37 is an optional step that comprises dewatering the
mixture. Optional
dewatering in step 37 may be similar to optional dewatering in option step 25
of method 20
(Figure 2). As discussed above, dewatering may serve a number of purposes,
which
include, without limation: (1) to remove unwanted soluble ions from solution,
and (2) to
adjust the ratio of magnesium oxide, magnesium chloride, and water.
Furthermore, in
embodiments of this invention where the base in step 32 is ammonium hydroxide,
dewatering will remove ammonium chloride from solution, so that it can
subsequently be
regenerated to ammonium hydroxide (e.g. through the Solvay Process)..
[0060] Step 38 comprises curing the mixture so that it can form cement.
The curing in
step 38 may be substantially similar to the curing described above in
connection with step
27 of method 20 (Figure 2). During the step 38 curing, magnesium oxychloride
(MOC) will
form, and trace amounts of magnesium oxysulfate (MOS) will also form
(depending on the
amount of sulfates in the brine).
[0061] The following examples are intended to illustrate the present
invention and to
teach one of ordinary skill in the art how to use the formulations of the
invention. They are
not intended to be limiting in any way, unless features of these examples are
recited in the
claims.
[0062] EXAMPLES
[0063] Example 1 ¨ Naturally-sourced brine with magnesium oxide added, with
gas then
bubbled through the mixture.
[0064] To a reaction chamber (in this example, a 3-neck flask) was added a
brine from
southern Alberta (3 L; Mg 35,000 ppm; Ca 50,000 ppm) and under mechanical
stirring
powdered MgO (1.60 kg; 40.2 mol) was added while monitoring the pH (which
reaches
approximately 10.5 after the addition of MgO). To the chamber was bubbled at a
flow rate of
0.5 L/min through a microbubble generator column an 11% CO2 89% air mixture of
gas that
was positioned vertically in the chamber. When the pH reached neutralization,
the bubbling
was stopped and the slurry was poured into a mould and sealed for 24 hours in
a 30 C
environment. After 24 hours the sample was demoulded and allowed to cure
further in
ambient condition of 20 C and 50% humidity for a period of 7 days. The
structural
performance was then evaluated through compressive strength testing of 2 inch
diameter
and 6 inch length cylinders in a universal testing machine (which tests the
compressive
strength of materials). Samples exhibited over 65MPa compressive strength.
Extent of
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carbonation was evaluated by thermogravimetric analysis (TGA) and powder x-ray
diffraction (PXRD) analysis and exhibited ¨8-10% carbonation.
[0065] Example 2 ¨ Synthetic brine containing no calcium ions with magnesium
oxide
added, with gas then bubbled through the mixture.
[0066] To a reaction chamber (in this example, a 3-neck flask) was added
MgC12.6H20
(2.70 kg; 13.3 mol) and under mechanical stirring powdered MgO (1.60 kg; 40.2
mol) was
added. To the chamber was bubbled at a flow rate of 0.5 L/min through a
microbubble
generator column an air stream of gas that was positioned vertically in the
chamber with
400 ppm CO2. When the pH reached neutralization, the bubbling was stopped and
the
slurry was poured into a mould and sealed for 24 hours in a 30 C environment.
After 24
hours the sample was demoulded and allowed to cure further in ambient
condition of 20 C
and 50% humidity for a period of 7 days. The structural performance was then
evaluated
through compressive strength testing of 2 inch diameter and 6 inch length
cylinders in a
UTM testing machine. Samples exhibited over 45MPa compressive strength. Extent
of
carbonation was evaluated by TGA and PXRD analysis to be less than 1%.
[0067] Example 3 ¨ Synthetic brine containing no calcium ions with magnesium
oxide and
ammonium hydroxide added.
[0068] To a reaction chamber (in this example, a 3-neck flask) was added
MgC12.6H20
(2.70 kg; 13.3 mol) dissolved in water (1.8L) and under mechanical stirring
powdered MgO
(1.60 kg; 40.2 mol) was added. Ammonium hydroxide was added. To the chamber
was
bubbled at a flow rate of 0.25 L/min through a microbubble generator column a
stream of
gas (11%CO2 and 89% air mixture) that was positioned vertically in the
chamber. When
the pH reached neutralization, the bubbling was stopped and the slurry was
filtered to
remove approximately 10% of the volume (soluble NH4CI) of the solution and was
poured
.. into a mould and sealed for 24 hours in a 30 C environment. After 24 hours,
the sample
was demoulded and allowed to cure further in ambient condition of 20 C and 50%
humidity
for a period of 7 days. The structural performance was then evaluated through
compressive
strength testing of 2 inch diameter and 6 inch length cylinders in a UTM
testing machine.
Samples exhibited over 55MPa compressive strength. Extent of carbonation was
evaluated
by TGA and PXRD analysis and demonstrated approximately 7% and 8% respectively
carbonates.
13
Date recue / Date received 2021-11-01
[0069] Example 4 ¨ Synthetic brine containing calcium and magnesium ions with
magnesium oxide and ammonium hydroxide added.
[0070] To a reaction chamber (in this example, a 3-neck flask) was added a
mixture of
CaCl2 (6.5 mol) and MgC12.6H20 (6.5 mol) dissolved in water (1.8L) and under
mechanical
stirring powdered MgO (1.60 kg; 40.2 mol) was added. Ammonium hydroxide was
added
and to the chamber was bubbled at a flow rate of 0.25 L/min through a
microbubble
generator column an 11% CO2 89% air mixture of gas that was positioned
vertically in the
chamber. When the pH reached neutralization, the bubbling was stopped and the
slurry was
filtered to remove approximately 10% of the volume (soluble NH4CI) of the
solution and
poured into a mould and sealed for 24 h in a 30 C environment. After 24 h the
sample was
demoulded and allowed to cure further in ambient condition of 20 C and 50%
humidity for a
period of 7 days. The structural performance was then evaluated through
compressive
strength testing of 2 inch diameter and 6 inch length cylinders in a UTM
testing machine.
Samples exhibited over 48MPa compressive strength at day 7. Extent of
carbonation was
evaluated by TGA and PXRD analysis.
[0071] Example 5 ¨ Microbubbles of Air
[0072] To a reaction chamber (in this example, 3-neck flask) was added a
mixture of CaCl2
(6.5 mol) and MgC12.6H20 (6.5 mol) dissolved in water (1.8L) and under
mechanical stirring
powdered MgO (1.60 kg; 40.2 mol) was added. Ammonium hydroxide was added. To
the
chamber was bubbled air at a flow rate of 0.25 L/min through a microbubble
generator
column that was positioned vertically in the chamber. When the pH reached
neutralization,
the bubbling was stopped and the slurry was filtered to remove approximately
10% of the
volume (soluble NH4CI) of the solution and poured into a mould and sealed for
24 h in a
C environment. After 24 h the sample was demoulded and allowed to cure further
in
25 ambient condition of 20 C and 50% humidity for a period of 7 days. The
structural
performance was then evaluated through compressive strength testing of 2 inch
diameter
and 6 inch length cylinders in a UTM testing machine. Samples exhibited over
33 Mpa
compressive strength at day 7.
Interpretation of Terms
30 [0073] Unless the context clearly requires otherwise, throughout the
description and the
claims:
14
Date recue / Date received 2021-11-01
= "comprise", "comprising", and the like are to be construed in an
inclusive sense, as
opposed to an exclusive or exhaustive sense; that is to say, in the sense of
"including, but not limited to";
= "connected", "coupled", or any variant thereof, means any connection or
coupling,
either direct or indirect, between two or more elements; the coupling or
connection
between the elements can be physical, logical, or a combination thereof;
= "herein", "above", "below", and words of similar import, when used to
describe this
specification, shall refer to this specification as a whole, and not to any
particular
portions of this specification;
= "or", in reference to a list of two or more items, covers all of the
following
interpretations of the word: any of the items in the list, all of the items in
the list, and
any combination of the items in the list;
= the singular forms "a", "an", and "the" also include the meaning of any
appropriate
plural forms.
[0074] Words that indicate directions such as "vertical", "transverse",
"horizontal", "upward",
"downward", "forward", "backward", "inward", "outward", "left", "right",
"front", "back", "top",
"bottom", "below", "above", "under", and the like, used in this description
and any
accompanying claims (where present), depend on the specific orientation of the
apparatus
described and illustrated. The subject matter described herein may assume
various
alternative orientations. Accordingly, these directional terms are not
strictly defined and
should not be interpreted narrowly.
[0075] While processes or blocks are presented in a given order, alternative
examples may
perform routines having steps, or employ systems having blocks, in a different
order, and
some processes or blocks may be deleted, moved, added, subdivided, combined,
and/or
modified to provide alternative or subcombinations. Each of these processes or
blocks may
be implemented in a variety of different ways. Also, while processes or blocks
are at times
shown as being performed in series, these processes or blocks may instead be
performed
in parallel, or may be performed at different times.
[0076] In addition, while elements are at times shown as being performed
sequentially, they
may instead be performed simultaneously or in different sequences. It is
therefore intended
Date recue / Date received 2021-11-01
that the following claims are interpreted to include all such variations as
are within their
intended scope.
[0077] Where a component is referred to above, unless otherwise indicated,
reference to
that component (including a reference to a "means") should be interpreted as
including as
equivalents of that component any component which performs the function of the
described
component (i.e., that is functionally equivalent), including components which
are not
structurally equivalent to the disclosed structure which performs the function
in the
illustrated exemplary embodiments of the invention.
[0078] Specific examples of systems, methods and apparatus have been described
herein
for purposes of illustration. These are only examples. The technology provided
herein can
be applied to systems other than the example systems described above. Many
alterations,
modifications, additions, omissions, and permutations are possible within the
practice of this
invention. This invention includes variations on described embodiments that
would be
apparent to the skilled addressee, including variations obtained by: replacing
features,
elements and/or acts with equivalent features, elements and/or acts; mixing
and matching
of features, elements and/or acts from different embodiments; combining
features, elements
and/or acts from embodiments as described herein with features, elements
and/or acts of
other technology; and/or omitting combining features, elements and/or acts
from described
embodiments.
[0079] Various features are described herein as being present in "some
embodiments".
Such features are not mandatory and may not be present in all embodiments.
Embodiments
of the invention may include zero, any one or any combination of two or more
of such
features. This is limited only to the extent that certain ones of such
features are
incompatible with other ones of such features in the sense that it would be
impossible for a
person of ordinary skill in the art to construct a practical embodiment that
combines such
incompatible features. Consequently, the description that "some embodiments"
possess
feature A and "some embodiments" possess feature B should be interpreted as an
express
indication that the inventors also contemplate embodiments which combine
features A and
B (unless the description states otherwise or features A and B are
fundamentally
incompatible).
[0080] It is therefore intended that the following appended claims and claims
hereafter
introduced are interpreted to include all such modifications, permutations,
additions,
16
Date recue / Date received 2021-11-01
omissions, and sub-combinations as may reasonably be inferred. The scope of
the claims
should not be limited by the preferred embodiments set forth in the examples,
but should be
given the broadest interpretation consistent with the description as a whole.
17
Date recue / Date received 2021-11-01
