Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Process for extracting hydrocarbons from oil sand
The present invention relates to a process for extracting hydrocarbons from
oil sand.
Oil sand occurs in many places on earth, for example in deposits in Venezuela
and
Canada. The oil sand consists essentially of a mixture of different
hydrocarbons (for
example low molecular weight, cyclic and open-chain, and especially also
bitumen),
sand and other minerals, and also water. The organic component of oil sand
consists
frequently of different hydrocarbons which feature a high viscosity at room
temperature
and which function as binders to the other components of the oil sand.
The typical mineral components in oil sand are sand, clay and particles of
various
rocks. These mineral components may consist of particles of different particle
size
according to the origin.
The water component of oil sand consists essentially of an aqueous film which
surrounds the sand grains or the mineral components. A typical oil sand
comprises, for
example, from 8 to 22% by weight of hydrocarbons and from about 3 to 6% by
weight
of water, and also sand and other mineral components.. The composition of the
oil sand
is subject to strong regional variations, and it is also possible for
different oil sand
deposits to occur at one geographical site, for example depending on the depth
of the
oil sand deposit.
In the last few years, various processes for extracting the hydrocarbons which
serve as
energy carriers and as chemical raw materials from the oil sand deposits have
been
developed. In a conventional hot water process, mixing of the oil sand with
hot water
with vigorous stirring in a tank at temperatures of from 60 to 95 C generates
a
multiphase system which is then separated into its phases in a multistage
process.
Various processes for treatment of oil sand are described, for example, in
US 6,007,708 and US 2007/0090025 A, but the known processes frequently enable
only an unsatisfactory yield of hydrocarbons or are technically very
complicated and
thus expensive. For instance, US 6,007,708 describes a process for extracting
bitumen
from oil sand, in which the oil sand is admixed with water and treated with an
air feed.
A subsequent separation phase is effected in a primary tank, in which a
separation into
bitumen foam, sand and a mixed phase is effected. Subsequently, the separated
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phases are sent to further processing. US 2007/009 0025 A also discloses a
multistage
process for extracting bitumen from oil sand. In this process, the bitumen-
containing
layer is sent to a flotation process after removal.
CA-A 2 276 912 discloses a process for removing bitumen from oil sand, in
which a
treatment with water and a nonflammable emulsifier is effected. The objective
in
CA-A 2 276 912 is to accelerate the separation of inorganic phase and oil
layer.
WO 2002/074 881, moreover, discloses a process for treatment of compositions
with a
low oil content, in which the material is treated at high temperatures and
application of
pressure in a reaction tank using water and a catalyst.
In the processes practiced, for example, in Canadian, Californian or
Venezuelan oil
sand deposits, the oil sand is first obtained by opencast methods and then
transported
to an extraction plant, in which an extraction is effected using hot water, pH
regulators
and further assistants. Before the extraction step, the oil sand is, if
appropriate,
conditioned in a mixer. The resulting hydrocarbon slurry is then pumped into
an
extraction plant, where the input of mechanical energy causes separation into
the
hydrocarbon component and the mineral component. Frequently, a gas is
introduced
(for example by blowing in hot air), as a result of which ultrasmall gas
bubbles become
attached to the hydrocarbon particles or hydrocarbon droplets, which can
result in
accelerated removal. This flotation process enables an improved yield of
hydrocarbons.
In the treatment of oil sand using water, hydrocarbons are found in the upper
foam
layer (phase A), in the aqueous phase (phase B) and in the (lower) solid phase
(phase
C).
In a separator, the hydrocarbon component collects to a considerable degree in
the
foam layer (phase A) (which floats on top). This foam layer can preferably be
removed
mechanically and comprises generally approx. 60% by weight of hydrocarbons,
approx.
30% by weight of water and about 10% by weight of extraneous substances.
This phase A can be treated using centrifuges and/or extraction methods. The
remaining residue consists of an aqueous phase (phase B) and a solid phase
(phase
C), and the two can either be separated, disposed of or used further. Various
processes and the corresponding apparatus are described, for example, in
US 2007/0131590.
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In an alternative process for extracting hydrocarbons from oil sand, water can
be
introduced into an oil sand deposit (especially in underground deposits) in
the form of
hot steam, which can achieve a separation of the bitumen component from the
mineral
component.
It is an object of the present invention to provide an improved process for
extracting
hydrocarbons from oil sand, in which the hydrocarbons can be removed from the
remaining components in an energy-saving process which can be carried out in a
technically simple manner. At the same time, both an efficient extraction of
hydrocarbons from an already extracted oil sand and a separation of
hydrocarbons in a
deposit (in situ) shall be enabled.
It is a further object of the present invention to provide a process in which
the following
criteria are substantially fulfilled:
a) the yield of hydrocarbons in phase A can be increased,
b) the process step of separation of the organic phase from extraneous
substances from aqueous phase B can be accelerated,
c) a reduction in the process temperature can be achieved,
d) the hydrocarbon content in the solid phase C can be reduced,
e) the content of nonhydrocarbons in phase A can be reduced,
f) the content of hydrocarbons in the wastewater and/or solid waste can be
reduced.
It has now been found that the extraction of hydrocarbons from oil sand can be
significantly improved and simplified by the addition of particular amounts of
specific
proteins during the treatment of the oil sand. The present invention also
relates to the
use of specific proteins, the so-called hydrophobins, for extracting
hydrocarbons from
oil sand.
Hydrophobins are small proteins of from about 100 to 150 amino acids, which
occur,
for example, in filamentous fungi such as Schizophyllum commune. They
generally
have 8 cysteine units in the molecule. Hydrophobins can be isolated from
natural
sources, but they can also be obtained by means of recombinant methods, as
disclosed, for example, in WO 2006/082 251 or WO 2006/131 564.
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The prior art has already proposed the use of hydrophobins for various
applications.
For instance, WO 1996/41882 proposes the use of hydrophobins as emulsifiers,
thickeners, surfactants, for hydrophilizing hydrophobic surfaces, for
improving the water
resistance of hydrophilic substrates, and for producing oil-in-water emulsions
or water-
in-oil emulsions.
Additionally proposed are pharmaceutical applications such as the production
of
ointments and cosmetic applications or the production of shampoos. EP-A 1 252
516
discloses the coating of various substrates with a solution comprising
hydrophobins at
a temperature of from 30 to 80 C. Also already proposed has been, for example,
the
use of hydrophobins as a demulsifier (see WO 2006/103251), as an evaporation
retardant (see WO 2006/128877) or soiling inhibitor (see WO 2006/103215).
In the context of the present invention, the term "hydrophobins" should be
understood
hereinafter to mean polypeptides of the general structural formula (I)
Xn-C'-X1-50-C2-XO-5-C3-X1-100-C4-X1-100-C5-X1-50-C6-XO-5-C7-X1-50-C8-Xm (I)
where X may be any of the 20 naturally occurring amino acids (Phe, Leu, Ser,
Tyr, Cys,
Trp, Pro, His, Gin, Arg, Ile, Met, Thr, Asn, Lys, Val, Ala, Asp, Glu, Gly). In
the formula,
the X radicals may be the same or different in each case. The indices beside X
are
each the number of amino acids in the particular part-sequence X, C is
cysteine,
alanine, serine, glycine, methionine or threonine, where at least four of the
residues
designated with C are cysteine, and the indices n and m are each independently
natural numbers between 0 and 500, preferably between 15 and 300.
The polypeptides of the formula (I) are also characterized by the property
that, at room
temperature, after coating a glass surface, they bring about an increase in
the contact
angle of a water droplet of at least 20 , preferably at least 25 and more
preferably 30 ,
compared in each case with the contact angle of an equally large water droplet
with the
uncoated glass surface.
The amino acids designated with C' to C8 are preferably cysteines. However,
they may
also be replaced by other amino acids with similar space-filling, preferably
by alanine,
serine, threonine, methionine or glycine. However, at least four, preferably
at least 5,
more preferably at least 6 and in particular at least 7 of positions C' to C8
should
consist of cysteines. In the inventive proteins, cysteines may either be
present in
reduced form or form disulfide bridges with one another. Particular preference
is given
to the intramolecular formation of C-C bridges, especially that with at least
one
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intramolecular disulfide bridge, preferably 2, more preferably 3 and most
preferably 4
intramolecular disulfide bridges. In the case of the above-described exchange
of
cysteines for amino acids with similar space-filling, such C positions are
advantageously exchanged in pairs which can form intramolecular disulfide
bridges
5 with one another.
If cysteines, serines, alanines, glycines, methionines or threonines are also
used in the
positions designated with X, the numbering of the individual C positions in
the general
formulae can change correspondingly.
Preference is given to using hydrophobins of the general formula (II)
Xn-C1-X3-25-C2-X0-2-C3-X5-50-C4-X2-35-C5-X2-15-C6-X0-2'C7-X3-35-CB-Xm (II)
to perform the present invention, where X, C and the indices beside X and C
are each
as defined above, the indices n and m are each numbers between 0 and 350,
preferably from 15 to 300, and the proteins additionally feature the above-
illustrated
change in contact angle, and, furthermore, at least 6 of the residues
designated with C
are cysteine. More preferably, all C residues are cysteine.
Particular preference is given to using hydrophobins of the general formula
(III)
Xn-C1-X5-9'C2-C3-X11-39-C4-X2-23-C5-X5-9'CB-C'-X6-18-C8-Xm (I11)
where X, C and the indices beside X are each as defined above, the indices n
and m
are each numbers between 0 and 200, and the proteins additionally feature the
above-
illustrated change in contact angle, and at least 6 of the residues designated
with C are
cysteine. More preferably, all C residues are cysteine.
The Xn and XR, residues may be peptide sequences which naturally are also
joined to a
hydrophobin. However, one residue or both residues may also be peptide
sequences
which are naturally not joined to a hydrophobin. This is also understood to
mean those
Xn and/or Xm residues in which a peptide sequence which occurs naturally in a
hydrophobin is lengthened by a peptide sequence which does not occur naturally
in a
hydrophobin.
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If X, and/or Xm are peptide sequences which are not naturally bonded to
hydrophobins,
such sequences are generally at least 20, preferably at least 35 amino acids
in length.
They may, for example, be sequences of from 20 to 500, preferably from 30 to
400 and
more preferably from 35 to 100 amino acids. Such a residue which is not joined
naturally to a hydrophobin will also be referred to hereinafter as a fusion
partner.
This is intended to express that the proteins may consist of at least one
hydrophobin
moiety and a fusion partner moiety which do not occur together in this form in
nature.
Fusion hydrophobins composed of fusion partner and hydrophobin moiety are
described, for example, in WO 2006/082251, WO 2006/082253 and WO 2006/131564.
The fusion partner moiety may be selected from a multitude of proteins. It is
possible
for only one single fusion partner to be bonded to the hydrophobin moiety, or
it is also
possible for a plurality of fusion partners to be joined to one hydrophobin
moiety, for
example on the amino terminus (Xn) and on the carboxyl terminus (Xm) of the
hydrophobin moiety. However, it is also possible, for example, for two fusion
partners
to be joined to one position (X, or Xm) of the inventive protein.
Particularly suitable fusion partners are proteins which naturally occur in
microorganisms, especially in Escherischia coli or Bacillus subtilis. Examples
of such
fusion partners are the sequences yaad (SEQ ID NO: 16 in WO 2006/082251), yaae
(SEQ ID NO: 18 in WO 2006/082251), ubiquitin and thioredoxin. Also very
suitable are
fragments or derivatives of these sequences which comprise only some, for
example
from 70 to 99%, preferentially from 5 to 50% and more preferably from 10 to
40% of the
sequences mentioned, or in which individual amino acids or nucleotides have
been
changed compared to the sequence mentioned, in which case the percentages are
each based on the number of amino acids.
In a further preferred embodiment, the fusion hydrophobin, as well as the
fusion partner
mentioned as one of the Xn or Xm groups or as a terminal constituent of such a
group,
also has a so-called affinity domain (affinity tag / affinity tail). In a
manner known in
principle, this comprises anchor groups which can interact with particular
complementary groups and can serve for easier workup and purification of the
proteins.
Examples of such affinity domains comprise (His)k, (Arg)k, (Asp)k, (Phe)k or
(Cys)k
groups, where k is generally a natural number from 1 to 10. It may preferably
be a
(His)k group, where k is from 4 to 6.
In this case, the Xn and/or XR, group may consist exclusively of such an
affinity domain,
or else an Xn or Xm radical which is or is not naturally bonded to a
hydrophobin is
extended by a terminal affinity domain.
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The hydrophobins used in accordance with the invention may also be modified in
their
polypeptide sequence, for example by glycosylation, acetylation or else by
chemical
crosslinking, for example with glutaraidehyde.
One property of the hydrophobins or derivatives thereof used in accordance
with the
invention is the change in surface properties when the surfaces are coated
with the
proteins. The change in the surface properties can be determined
experimentally, for
example, by measuring the contact angle of a water droplet before and after
the
coating of the surface with the protein and determining the difference of the
two
measurements.
The performance of contact angle measurements is known in principle to those
skilled
in the art. The measurements are based on room temperature and water droplets
of
5 l and the use of glass plates as substrate. The exact experimental
conditions for an
example of a suitable method for measuring the contact angle are given in the
experimental section. Under the conditions mentioned there, the fusion
proteins used in
accordance with the invention have the property of increasing the contact
angle by at
least 20 , preferably at least 25 , more preferably at least 30 , compared in
each case
with the contact angle of an equally large water droplet with the uncoated
glass
surface.
Particularly preferred hydrophobins for performing the present invention are
the
hydrophobins of the dewA, rodA, hypA, hypB, sc3, basfl, basf2 type. These
hydrophobins including their sequences are disclosed, for example, in WO
2006/082
251. Unless stated otherwise, the sequences specified below are based on the
sequences disclosed in WO 2006/082 251. An overview table with the SEQ ID
numbers can be found in WO 2006/082 251 on page 20.
Especially suitable in accordance with the invention are the fusion proteins
yaad-Xa-
dewA-his (SEQ ID NO: 20), yaad-Xa-rodA-his (SEQ ID NO: 22) or yaad-Xa-basfl-
his
(SEQ ID NO: 24), with the polypeptide sequences specified in brackets and the
nucleic
acid sequences which code therefor, especially the sequences according to SEQ
ID
NO: 19, 21, 23. More preferably, yaad-Xa-dewA-his (SEQ ID NO:20) can be used.
Proteins which, proceeding from the polypeptide sequences shown in SEQ ID NO.
20,
22 or 24, arise through exchange, insertion or deletion of from at least one
up to 10,
preferably 5 amino acids, more preferably 5% of all amino acids, and which
still have
the biological property of the starting proteins to an extent of at least 50%,
are also
particularly preferred embodiments. A biological property of the proteins is
understood
here to mean the change in the contact angle by at least 20 , which has
already been
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described.
Derivatives particularly suitable for performing the present invention are
derivatives
derived from yaad-Xa-dewA-his (SEQ ID NO: 20), yaad-Xa-rodA-his (SEQ ID NO:
22)
or yaad-Xa-basfl-his (SEQ ID NO: 24) by truncating the yaad fusion partner.
Instead of
the complete yaad fusion partner (SEQ ID NO: 16) with 294 amino acids, it may
be
advantageous to use a truncated yaad residue. The truncated residue should,
though,
comprise at least 20, preferably at least 35 amino acids. For example, a
truncated
radical having from 20 to 293, preferably from 25 to 250, more preferably from
35 to
150 and, for example, from 35 to 100 amino acids may be used. One example of
such
a protein is yaad40-Xa-dewA-his (SEQ ID NO: 26 in PCT/EP2006/064720), which
has
a yaad residue truncated to 40 amino acids.
A cleavage site between the hydrophobin and the fusion partner or the fusion
partners
can be utilized to split off the fusion partner and to release the pure
hydrophobin in
underivatized form (for example by BrCN cleavage at methionine, factor Xa
cleavage,
enterokinase cleavage, thrombin cleavage, TEV cleavage, etc.).
The hydrophobins used in accordance with the invention for treatment of oil
sand can
be prepared chemically by known methods of peptide synthesis, for example by
Merrifield solid-phase synthesis.
Naturally occurring hydrophobins can be isolated from natural sources by means
of
suitable methods. Reference is made by way of example to Wosten et al., Eur. J
Cell
Bio. 63, 122-129 (1994) or WO 1996/41882. A recombinant production process for
hydrophobins without fusion partners from Talaromyces thermophilus is
described by
US 2006/0040349.
Fusion proteins can be prepared preferably by genetic engineering methods, in
which
one nucleic acid sequence, especially DNA sequence, encoding the fusion
partner and
one encoding the hydrophobin moiety are combined in such a way that the
desired
protein is generated in a host organism as a result of gene expression of the
combined
nucleic acid sequence. Such a preparation process is disclosed, for example,
by WO
2006/082251 or WO 2006/082253. The fusion partners considerably ease the
production of the hydrophobins. Fusion hydrophobins are produced with
significantly
better yields in the recombinant processes than hydrophobins without fusion
partners.
The fusion hydrophobins produced by the host organisms by the recombinant
process
can be worked up in a manner known in principle and can be purified by means
of
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known chromatographic methods.
In a preferred embodiment, the simplified workup and purification process
disclosed in
WO 2006/082253, pages 11/12, can be used.
In this process, the fermented cells are first removed from the fermentation
broth and
disrupted, and the cell fragments are separated from the inclusion bodies. The
latter
can advantageously be done by centrifugation. Finally, the inclusion bodies
can be
disrupted in a manner known in principle, for example by means of acids, bases
and/or
detergents, in order to release the fusion hydrophobins. The inclusion bodies
comprising the fusion hydrophobins used in accordance with the invention can
generally be dissolved fully even using 0.1 M NaOH within approx. 1 h.
The resulting solutions can - if appropriate after establishing the desired pH
- be used
without further purification to perform this invention. However, the fusion
hydrophobins
can also be isolated as a solid from the solutions. The isolation can
preferably be
effected by means of spray granulation or . spray drying, as described in
WO 2006/082253, page 12. The products obtained by the simplified workup and
purification process comprise, as well as residues of cell fragments,
generally from
approx. 80 to 90% by weight of proteins. The amount of fusion hydrophobins is,
according to the fusion construct and fermentation conditions, generally from
30 to 80%
by weight based on the amount of all proteins.
The isolated products comprising fusion hydrophobins can be stored as solids
and be
dissolved in the media desired in each casefor use.
The fusion hydrophobins can be used to perform this invention as such or else,
after
eliminating and removing the fusion partner, as "pure" hydrophobins. A
splitting is
advantageously undertaken after the isolation of the inclusion bodies and
their
dissolution.
The present invention relates to a process for extracting hydrocarbons from
oil sand, in
which the oil sand is treated in a separation apparatus in at least one
process step with
a composition which comprises a hydrophobin derivative. If appropriate the
composition which comprises a hydrophobin derivative may comprises further
assistants.
Preferably, the hydrophobin derivative is used together with water and the
amount of
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hydrophobin derivative, based on the overall composition composed of oil sand,
water
and additives, is from 0.1 to 1000 ppm. In particular, the used hydrophobin
derivative is
a fusion hydrophobin or a derivative thereof.
5 In a preferred embodiment, in the process for extracting hydrocarbons from
oil sand an
aqueous composition which comprises, as well as the hydrophobin derivative, at
least
one further compound which improves the phase separation of water and
hydrocarbon
phase is used.
10 More preferred, the used hydrophobin derivative is a fusion hydrophobin
selected from
the group of yaad-Xa-dewA-his (SEQ ID NO: 20), yaad-Xa-rodA-his (SEQ ID NO:
22)
or yaad-Xa-basfl-his (SEQ ID NO: 24), were yaad may also be a truncated yaad'
fusion partner having from 20 to 293 amino acids.
In a further preferred embodiment, the invention relates to a extracting
process as
described above wherein an oil sand which comprises from 5 to 25% by weight of
hydrocarbons, from 3 to 8% by weight of water and from 70 to 95% by weight of
inorganic components is mixed thoroughly with an aqueous composition which
comprises from 10 to 80% by weight of water and from 1 to 1000 ppm of
hydrophobin
derivative at a temperature of from 15 to 95 C, and, after a separation phase,
a
removal of the hydrocarbon-containing phases and further purification steps of
these
hydrocarbon-containing phases are effected. If appropriated in the process
mentioned
above for extracting hydrocarbons from oil sand, an oil sand is comminuted and
prepurified before mixed thoroughly with an aqueous composition.
Furthermore, the present invention is directed to the use of a composition
comprising at
least one hydrophobin derivative for extracting hydrocarbons from oil sand,
wherein the
hydrophobin derivative is particularly used in the mixing of oil sand with an
aqueous
phase.
Preferably, the invention is directed to the use of a composition comprising
at least one
hydrophobin derivative for extracting hydrocarbons from oil sand, wherein the
hydrophobin derivative is used in an amount of from 0.1 to 1000 ppm based on
the
overall composition, more preferred in an amount of from 10 to 150 ppm based
on the
overall composition.
In the process according to the invention for extracting hydrocarbons from oil
sand, in
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which the oil sand is treated with an aqueous composition which comprises a
hydrophobin, it is possible, for example, to carry out a process sequence
shown in the
flow diagram in Figure 1.
In Figure 1, the oil sand (OS) is first transported from an oil sand deposit
(1) into an
extraction plant (2).
Raw water (RW) is fed into the extraction plant (2) from a raw water tank (5).
In the
extraction plant (2), the oil sand is mixed thoroughly with the raw water. The
additives
(AD) - for example the hydrophobin and/or other additives - can be introduced
separately into the extraction plant (2), but they can also be introduced
together with
the raw water introduction (RWI).
In the flow diagram shown in Figure 1, the wastes (R) of the extraction
process are
removed from the extraction plant (2). In addition, the bitumen foam (BF) is
removed
and sent to a further processing unit (3), in which foam processing and
solvent
recovery takes place. The waste layer (TS) is withdrawn from the extraction
plant (2)
and passes into a collecting tank (6), in which a splitting into recoverable
water (RW)
and recovered bitumen (RB) can take place. The recovered water (RW) can be fed
into
the water reservoir vessel (5); the recovered bitumen (RB) can be recycled
into the
extraction plant (2).
The composition (B) obtained from the bitumen foam (BF) in the plant (3),
which
comprises a high proportion of hydrocarbons, is, if appropriate, sent to a
further
reprocessing step in a plant (4). In this case, the composition can also be
heated and
subjected to further wash processes. The hydrocarbon-rich compositions (RF)
obtained
can then be sent to a refinery. For the performance of the bitumen foam
treatment in
the process unit (3), the additional introduction of a solvent (S) may be
advisable.
The waste products of the bitumen processing step obtained in the processing
unit (3)
include water, inorganic solids, asphalt, solvents and small amounts of
bitumen. These
waste products (T) can, if appropriate, be finally stored.
To illustrate the process according to the invention for extracting
hydrocarbons from oil
sand, a more precise flow diagram for the hydrocarbon extraction is shown in
Figure 2.
Starting from an oil sand slurry (CS), which can be pumped, for example,
through a
pipeline to the plant, it is fed into the primary separation unit (PSC). This
separation
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unit (10) serves for the first splitting of the oil sand slurry fed in. The
hydrocarbon-
containing foam (PSCF) obtained in a first step using water and hydrophobin is
removed and fed to a further separation unit (12), into which, for example,
steam or air
can be fed. From this separation unit (12), the hydrocarbon-containing foam
can be
passed on into a processing unit (14) in which foam treatment is effected.
In the primary separation unit (10), a middle layer (M) (mixed phase) is also
obtained,
which can be sent to a flotation process in a flotation plant (16). From this
flotation plant
(16), a hydrocarbon-containing slurry can be recycled back into the primary
separation
unit (10). The wastes of the flotation process (PFT) can be sent to a
secondary flotation
process in a further flotation plant (18). The wastes of the flotation
processes can
undergo splitting into solid wastes (26) which can be disposed of by landfill
(such as
slightly contaminated sand) and water (W), which can either be disposed of or
preferably recycled into the process.
In the treatment of the flotation wastes, a more rapid and improved separation
into solid
wastes and liquid constituents can be effected in the plant, for example, as a
result of
addition of thickeners from a reservoir vessel (22). The foam (F) obtained in
the
flotation steps can be recycled into the primary separation process in the
plant (10).
The examples which follow are intended to illustrate the invention in detail:
Example 1 Provision and testing of the hydrophobins
For the examples, one fusion hydrophobin with the complete yaad fusion partner
(yaad-Xa-dewA-his; referred to hereinafter as hydrophobin A) and one fusion
hydrophobin with a yaad40-Xa-dewA-his (hydrophobin B) fusion partner truncated
to
40 amino acids were used. The hydrophobins were prepared by the procedure
described in WO 2006/082253. The products were worked up by the simplified
purification process according to Example 9 of WO 2006/82253 and spray-dried
according to Example 10. The total protein content of the resulting dried
products was
in each case from approx. 70 to 95%by weight; the content of hydrophobins was
from
approx. 40 to 90% by weight based on the total protein content. The products
were
used as such for the experiments.
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Performance testing of the hydrophobins:
Characterization of the fusion hydrophobins by contact angle variation of a
water
droplet on glass (window glass, Suddeutsche Glas, Mannheim):
For the tests, the spray-dried products comprising fusion hydrophobins were
dissolved
in water with addition of 50 mM sodium acetate pH 4 and 0.1 % by weight of
polyoxyethylene(20) sorbitan monolaurate (Tween 20). The concentration of the
product was 100 g/ml in aqueous solution.
Procedure:
- Incubation of glass platelets overnight (temperature 80 C), then wash
coating in
distilled water,
- then incubation 10 min/80 C/1 % sodium dodecylsulfate (SDS) solution in
dist.
water,
- washing in dist. water.
The samples are dried under air and the contact angle (in degrees) of a
droplet of 5 pl
of water at room temperature is determined. The contact angle measurement was
determined on a dataphysics contact angle system OCA 15+, Software SCA 20.2Ø
(November 2002). The measurement was effected according to the manufacturer's
instructions.
Untreated glass gave a contact angle of from 15 to 30 5 . Coating with the
fusion
hydrophobin yaad-Xa-dewA-his6 gave a contact angle increase of more than 30 ;
coating with the fusion hydrophobin yaad40-Xa-dewA-his likewise gave a contact
angle
increase of more than 30 .
Example 2 Analysis of the oil sand
The oil sand analyzed here consists of the following components:
- 8 to 22% by weight of hydrocarbons (bitumen)
- approx. 5% water
- from 75 to 90% sand (mainly quartz, approx. 10% clay as fines < 44 m).
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The analysis results obtained were in particular:
a) solids content: 96.9% (by means of IR drying)
b) extractable organic substances: from 120 to 130 g/kg (Soxhlet extraction),
c) C10 to C40 hydrocarbon content (boiling range from 175 to 525 C): 35 g/kg,
d) sum of all polyaromatics: 9.9 g/kg,
e) sum of nonalkylated polyaromatic hydrocarbons: 22 mg/kg.
For the measurement of the particle size distribution, a separation of oil
sand using
hexane as the solvent was carried out. 10 g of oil sand were mixed with
approx. 70 ml
of hexane, and the bitumen fractions were leached out.
For the particle size distribution, see the table which follows.
Size Volume
10-6m below %
0.265 0.00
0.337 0.02
0.427 0.13
0.542 0.39
0.688 0.88
0.874 1.71
1.11 2.96
1.41 4.63
1.79 6.71
2.27 9.08
2.88 11.60
3.65 14.14
4.64 16.67
5.88 19.22
7.47 21.79
9.48 24.35
12.03 26.92
15.27 29.50
19.38 32.11
25.00 34.88
31.22 37.27
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39.62 39.98
50.28 43.21
63.82 47.60
81.00 53.90
102.8 62.70
130.5 73.98
165.6 85.37
210.2 94.15
266.8 99.06
338.6 100.0
The distribution of the particle sizes is broad between 0.5 and 300 m. The
mean
particle diameter is at d50 = 70 m. The removal of the sand from the organic
component (bitumen) is associated with a relatively high level of cost
inconvenience
5 especially for the finer particles. The sand particles at approx. 100 pm can
be removed
by centrifugation.
Example 3 Exploratory, noninventive laboratory test for bitumen extraction
10 Beaker tests are carried out, initially without the flotation which is
customary in the
industrial standard process but is difficult in the laboratory (foam formation
of the
bitumen as a result of air and energy introduction). However, comparable
flotation tests
using hydrophobin can also be carried out without technical difficulties. The
exploratory
tests are used to provide the comparative basis for the visual assessment of
the
15 inventive bitumen extraction in Example 4.
In the beaker test, the oil sand is admixed with water in a mass ratio of 8:10
and with
different amounts of NaOH (setting of the pH from 7 to 11) for pH regulation.
Settling
tests are carried out at temperatures of 40, 60, 80 C with 30 minutes of
stirring time
and 30 minutes of settling time.
The stirrer speed is selected at about 500 revolutions per minute such that
complete
dispersion is achieved, i.e. such that no lasting coherent areas of one phase
can form
on the surface. The stirring is associated with minor introduction of air.
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After 30 minutes of settling, a characteristic settling profile with
(essentially) three
layers is formed for all samples, which are shown and illustrated in Figure 3.
Figure 3 shows the test results of the beaker tests in schematic form.
The basis used for the creation of the graphic illustrations was the
photographs taken
when the tests were performed.
Figure 3 shows three different processes for separating oil sand (V1, V2 and
V3; V2
and V3 are explained in Example 4). In the test designated V1, an oil sand
treated with
water without the addition of hydrophobin is shown. The layer (31) consists of
the
hydrocarbon-containing liquid bitumen which, owing to the low gas introduction
in the
course of stirring, comprises only a small amount of foam. The middle layer
(32)
consists of a complex mixed phase composed of hydrocarbons, sand, further
inorganic
components and water. The layer (33) consists predominantly of settled
contaminated
sand. The separation into the three layers takes a long time and is
incomplete.
Between layers 32 and 33, there is additionally a very thin layer of bitumen.
The
bitumen fraction which settles here is a small portion of the total amount of
bitumen and
has a density which is greater than that of the aqueous layer (32).
Assessing the quality of the separation is not unproblematic. The depletion of
the
bitumen from the sand is one factor, but others are the sand/fines content in
the
aqueous phase and the water content in the bitumen phase. For the tests, the
criterion
used for the separation quality is the total carbon content in the sand
sediment. For the
analysis, the sand layer has to be sufficiently dense. This is ensured only
after approx.
minutes' settling. The liquid phases are cautiously decanted and then the
bitumen
25 layer above the sand is pushed to the side with a spatula. A sample can
then be taken
from the sediment.
A pH of 11 provides the best depletion from the sand in several tests, which
reflects the
literature data for the parameters of the currently used oil sand extraction.
An influence
30 of the change in temperature cannot be discerned from these measurements.
Example 4 Tests with addition of hexane without and with hydrophobin
For the further tests, the flotation is replaced by the addition of hexane as
a solvent for
the hydrocarbons. As a result of the use of hexane, a better separation is to
be
expected than in Example 3, in which only water is used. The addition of
sodium
hydroxide solution is dispensed with, which in turn leads, if anything, to
worsened
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depletion of the bitumen from the sand.
In the industrial standard extraction process, a hydrocarbon is used only
after the
flotation and centrifugal removal of solids.
Test parameters of beaker tests with hexane and hydrophobin:
- beaker: volume approx. 200 ml
- volume ratio of sand:water:hexane = 50 ml:100 ml:50 ml,
- mass ratio of 59 g:93 g:33 g
- 45 C
- stirrer bar speed 750 revolutions per minute
- initial stirring time 15 minutes, then stir again for 5 minutes in each case
after
the addition of the hydrophobin
- hydrophobin addition in powder form
- hydrophobin from 1 mg/kg to 1000 mg/kg based on total amount, pH = 7
The phase separation is assessed visually. The result is likewise shown in
Figure 3.
In the beaker designated V2, the oil sand is used with water and the hexane
solvent
but without hydrophobin. This gives rise to a bitumen-containing hexane phase
(34), a
nontransparent complex middle layer (32) comprising hydrocarbons, sand,
suspended
inorganic substances and water, and a layer of sand as sediment (33). Layer
(34) takes
up a somewhat greater volume than (31), since hexane is used additionally.
(32) and
(33) correspond visually to the layers from Example 3.
In the beaker designated V3, the oil sand is treated with water, hydrophobin
being
added to the water in an amount of 100 mg of protein per kg of the mixture. In
addition,
the hexane solvent is added. Even after a short time, a clearly separated
triphasic
system is obtained. The bitumen-containing hexane phase occurs as phase (34);
as
the middle phase (35), a clear aqueous phase which comprises essentially no
suspended inorganic substances and no sand is observed. In addition, a
sediment
phase (33) composed of only slightly contaminated sand is observed.
The sediment phases (33) are identical by visual assessment in all tests.
However, the
sediment layer in V3 is lighter than in V1 and V2, which indicates improved
bitumen
depletion from the sand.
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The hydrophobin was also used in lower and higher concentrations than 100
mg/kg.
The results can be summarized as follows:
- the aqueous phase becomes rapidly clear at an added amount of 100 mg/kg.
- an optimum is discernible at 100 mg/kg of hydrophobin.
- at significantly lower and higher concentrations of hydrophobin, the aqueous
phase becomes similarly cloudy to that without addition of hydrophobin.
- negative effects through the repeated stirring are ruled out through the
addition
of hydrophobin compared to a blank test without addition.
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