Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This inven-tion deals with the recovery of bitumen
from aqueous effluents from tar sands separation processes
utili7ing water media, particularly from the hot water pro-
cess. The aqueous effluent containing bitumen is scrubbed ;
using hydrophobic carbon such as refinery coke, the coke being
combined with the bitumen from added tar sands, to form a
composite organic phase which is separated and recovered.
The hot water process is in use in Alberta to
treat tar sands for recovery o bitumen. The tar sands
are slurried with hot water a~d steam, the pulp is a~itated
ana fed to a separation vessel. Entrained air causes the
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bitumen to rise to the top of the vessel as a froth. The
separated froth is usuall~ further treated as by centri~uge
to remove addi~ional mineral solids. ~he aq~leous phase con-
ta.in~ hydrophilic qolids and some bitumen. Much o~ the sand
settles out from the aqueous phase bu-t very fine hydrophilic
solids such as clays/ and entrained or emulsified bitumen
material are very difficult to remove from the aqueous tai-
lings. Even prolonged settling in ponds will not completely
separate the clays etc. and the lost bitumen materia:Ls from
the a~ueous phase.
Many e~forts have been made to separate the sus-
pended solids rom the aqueous phase, and to re-use the tai-
lings water. U.S. Patent 3,816,305, Schutte describes the
, addition of acid to tailings and middlings water to accele-rate clariication. U.S. Patent 3,607,720, Paulson utilizes ~ ;
hot flue gases to treat pond water from tar sands processing.
` U.S. Patent 3,526,585, Camp adds a volatile organic fluid
;j immiscible with water to the pond water to form an inter-
'1 30 face layer higher in clay content. U.S. Patent 3,487,003,
Baillie et al treats the pond water with a flocculating
agent, pH change and centrifuging.
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Canadian Patent 982,966, February 3, 1976, Maloney,
describes recycling tar sands hot water process effluen-t to
contact fresh tar sands in a kneading agglomerating zone,
and recovering tar agglomerates, sand and an effluent
stream of reduced clay, silt and bitumen con-tent. No
amounts of bitumen recovered from the effluent are given.
We have now found that improved recoveries of
waste bitumen from tar sands process aqueous effluent can
be achieved by incorporating hydrophobic carbon as scrub-
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bing or nucleating agent toge~her with added tar sands and
recycled effluent. The mixture must be subjected to agita-
tion with shearing action and agitation continued until a
unit.ary organic phase orms. This organic phase is readily
separated by physical means.
The lnventi.on i.~ more particularly a method for
'l ~ recovering tar sand~ l~iturnen concurrently from tar salids
and rom aqueous e1uents ~rcm water-based proces~es for ~ -
treating tar sands, comprising: -
(a) recycling aqueous e~fluent conta.Lnin~ waste
bitumen and incorporating therewi~h
i) hydropho~ic carbol in amounts of about 0.5 to
5% by wt. based on the tar sands, and
ii) tar sand~s in amounts yielding a 1uid
slurry;
~b) agïtating with shearing action the ternary
mixture to contact intimately the carbon with the effluent
and added tar sand to cause the hydrophobic surfaces to scrub
organic material from the ef~luent, and continuins agitation
until the carbon and bitumen from the e1uent orms into
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i 30 a unitary organic phase with the bitumen from the -tar sands;
~ ~c) separating the unitary organic phase rom the
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aqueous phase and from the bulk of the mineral solids, and
discharging a~ueous effluent of reduced organic con-tent;
and (d) recovering carbon and hydrocarbons from ~he
organic phase. -
The hydrophobic carbon can be any solid ~orm of car-
bon which is not wetted by water bu-t is we-tted by the bitumen
phase. Hydrophobic forms of low grade coal, coke and carbon
adsorbents may be used. A local refinery coke or '!delayed`'
coke, particularly one prepared from tar sands bitumen has been
found very satisfactory. It is possible to recover and re-
cycle the initial carbon solids, e.g., b~ solvent washing
and retorting of the organic phase. The amount of the ~,f.~.. ' .
hydrophobic carbon solids incorporated is suitabl~ about
0.5 t~ about 5~ by wt. based on the tar sands. ~he par~icle
si2e o the carbon solids can vary widely. The larger the
particle size, the easier to separate the organic phase as ~ ;
by screening. Usually the particle size will be less than
about 0.3 mm diameter or passing a 50 mesh screen, to give
an adequate surface area for contact with bitumen. -
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The effluent containing waste bitumen can be ob-
tained directly from a hot-water or similar ~ar sands sepa-
ration process, or from ponds resulting from such processes.
The effluent can be from lower settled-out layers of such
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effluent ponds including so-called sludge layers. Usuallyr
the effluent will contain about 0.5 to 2% wt. or more bitu-
men material. The settled pond layers or sludge will con- -
;` tain up to 5~ or more of bitumen. The solids content of
the effluent is usually within about 5 to 10% wt. in the
form of a stabIe colloidal suspension.
The mixing may be carried out in two stages, e.g.,
the carbon and tar sands pre-mixed, and then incorporated
with the major portion of effluent. The pre-mixing is
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suitably at low water contents not more than about 15 - 20%
wt., and the effluent then added to raise -the water content
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to at leas-t about 30% wt. (based on total mixture), usually -
to at least 50%. ~arge amounts of effluent can be scrubbed
by the carbon and bitumen, e.g., amounts of about 200% wt.
or higher based on wt. of tar sands (see Example III).
The agitation may be carried out by any suitable
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means but should be accompanied by a definite shearing action.
A milling action, as bekween hard solid surfaces urged to-
gether, is preferred. This milling action is believed to
expose hydrophilic surfaces of the mineral solids and faci-
litate their transfer to the a~ueous phase, as well as aid
the scrubbin~ ac~ion of the carbon solids on the a~ueous
phase. It is preferred to carry out an initial milling
action on a partial mi~ture of hyd~ophobic carbon and tar
sands to aid disruption of the tar sands (see Examples).
The separation of the resulting unitary organic
phase of carbon solids plus bitumen is readily achieved by
screening or coarse filtration. Centrifugal action can also
be used. It is desirable to wash the organic phase with
water to help remove hydrophilic impurities. This washing
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can conveniently take place in the separation zone to faci-
litate removal of the wash water. `~
The agitation and separation are suitably carried
; out at ambient temperatures. If the recycled effluent is -
warm, say up to about 50C, the scrubbing action and uni-
tary organic phase formation appear to proceed more quickly.
Some reduction in process time is also possible if the pH
is raised slightly, e.g., to pH 8-9 with alkali metal
l 3Q hydroxide.
`~3 The separated organic phase is further processed
, by conven-tional techniques to recover carbon ~olids and
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hydrocarbons. The orgniac phase can be retorted to sepa-
rate gaseous and liquid products from the solid residue.
Solvent washing can be used -to aid separation of bitumen ma-
terial from the carbon solids. A coking operation can be
carried out on part or all of the organic phase to yield
coke and volatile products. In the unitary organic phase
some fine mineral solids may remain entrained, but these
solids are believed to be beneficial in~coke prepared from ` `
this phase by improving coke combus~ion properties. A ;
cracking operation can be incorporated in these recovery
techniques if desired. Whatever recovery scheme is used, --
it is usually desirable to obtain some hydrophobic carbon
for recycle.
The final aqueous phase or eE~luent will have a
reduced organic content usually corresponding to a loss-on-
ignition of about 5 to 10% (when starting with about 27%
L.O.I. hot-water process pond effluent sludge). The re-
duction in organic content from feed effluent to final
effluent is normally to 1/5 - 1/10 or less of the initial
content. This final effluent is depleted in organic sub-
stances responsible ~or the slow settling of clay etc. r~
~olids, and these solids will now settle out more rapidly
yielding water which can be recycled or at least is more
acceptable for discharge to the environment.
The following examples are illustrative The
hydrophobic carbon (nucleating agent) was refinery coke
which was wet ball-milled to -140 mesh and filtered. The
moist ~ilter cake containing about 44% solids was used in
-the process. The effluent used was hot-water process pond
e~fluent. Loss on ignition is % of dry solids content.
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Example I
Part (1) Clay-type Tar Sand 200 g (bitumen content 5.9~)
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Moist ~efinery Coke 25 g (abou-t 10.9 g solids)
These two were admixed by rotating in a quart-
size porcelain jar containing 5 s-teel 1/2" diameter balls
for 2 hours. About 200 ml of water eEfluent containing
about 26.6% non-aqueous material (bitumen + inorganic mine- -
rals) was added and the jar rotated for 20 hours. About
225 ml aqueous phase tl) was removed by screening.
Part (2) About 200 g clay-type -tar sand was added to the
oil phase from (1) above, and rotated in the jar for 30
minutes. Then about 200 ml effluent as above was added and
the suspension rotated in the jar for 10 hours. About 220
ml o~ aqueous phase (2) was .removed by screening.
Part (3) ~ further 200 g ~uantity of clay-type tar sand
and 200 ml effluent were added and treated as in part t2).
i The aqueous tailings (3) were separated from the oil phase i
by screening. The oi] ~hase was worked twice by rotating
15 minutes with 100 ml clear water each time and screened~
The results obtained are summarized below:
Separated Solids Loss on Bitumen Re-
Tailings Content Ignition Covered from
% ~ 600 ml E~fluent
and tar sands
Part
.
1 51.4 5.83
2 43.6 6.47 - --
3 49.4 7.32 51~8 g
Blank (Pond (hot water pro-
30Effluent) 26.6 26.9 cess effluent) ;
) About 131.95 g oil phase was recovered containing
38.2~ solids (includes the refinery coke) and 23.6~ water.
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Judging from the loss on ignition (L.O.I.) as in-
dicator, gooc1 bitumen separa-tion from effluent was achieved
by this method.
Example IIa
Control - No nucleatinq a~ent added
Part (la) Clay-type Tar Sand 200 g (bitumen content 5.9%) ~-
Hot-water process ~
effluent 200 ml ~26.6% non-aqueous material) -
These materials were admixed in a quart-size por-
celain jar by rotating 10 hou~s using 5 steel 1/2l' balls. -
The oil appeared present in "islands". About 150 ml of
aqueous suspension (la) was separated by screening.
Part (2a) About 200 g clay-t~pe tar sand as above was added ! '' .,'
to this resulting oil phase and the system admixed b~ ro-
tating 30 minutes. Then 200 ml hot-waker process eE~luent ` i
was added and the system again rotated for 5 hours. About
100 ml aqueous phase (2a) was separated by screening. The
oil phase was rinsed twice by rotating 15 minutes with S0
ml clear water each time (3a). The results obtained are
summarized below:
Separated Solids Loss on Bitumen Re-
Tailings Content Ignitioncoverecl from
% ~ 400 ml EEEluent
and tar sands
Part
la 54 2 5.62
2a 54.4 19.15 -
3a 41.4 10.45 16.75 g
.
About 33.6 g bitumen product was recovered contai- -
ning 27.6% solids and 22.5% water.
; 30 Example IIb
Same as Control Example IIa, except refinery coke added
Part (Ib) About 200 g clay-type tar sand (5.9% bitumen) was
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admixed with 25 g moist xefinery coke ground to 140 mesh
(10.9g solid) by rotating in a quart-size porcelain ~ar
containing 5 steel 1/2" balls for 1 hour. The total solids
were in the form of spherical bodies. Abou-t 200 ml hot-
water process effluent (26.6% non-aqueous solids) was added
and the jar rotated for 10 hours. The oil phase was sub-
stantially in one mass. About 160 ml aqueous suspension was
separated by screening (lb).
Part (2b) About 200 g clay-type tar sand was added -to oil
phase from (lb) and admixed by rotating 30 minutes, then
200 ml hot-water process effluent containing about 26.6%
non-aqueous solids (bitumen ~ inorganics) was adcled and the
entire system rotated for 5 hours. About 185 ml aqueous
suspension (2b) was separated b~ screening. The oil phase
was rinsed twice by rotating for 15 minutes with 50 ml of
clear water each time and screened. The washings were com-
bined as tailings (3b). The results from example IIb are
su~lmarized below:
Separated Solids Loss onBitumen Re-
20 Tailings Content IgnitionCovered from
% % 400 ml Effluent
and tar sands
Part
lb 57.1 5.93
2b 58.4
3b 38.7 6.33 41.6 g
About B8.0 g bitumen product was recovexed containing
about 23.9% water and 28.2% solids which included the refi- -
nery coke.
Example III -
~ 30 About 200 g clay-type tar sand (5.9% bitumen) was
! admixed with 15 g moist refinery coke as in example IIb, but
rotating for 30 minutes. The entlre system pelletized.
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About 400 ml effluent from the hot-water process tailings
- pond was added and the suspension admixed by rotating 10
hours. About 380 ml aqueous suspension was screened off (-).
The oil phase was rinsed twice by rotating for 15 minutes
with 50 ml clear water each time. The results are summarized
below:
Separated Solids Loss of Bi-tu~en Re- -~
Tailings Content Ignition Covered from
% 400 ml effluent
and tar sands
1 46 6.18 41.1 g
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About 74.6 g bitumen product was recovered contai-
ning about 23.7P6 water and 21.2% solids (including the re-
finery coke).
~xample IV
About 400 g clay-type tar sand (5.9% bitumen) was
admixed with 10 g moist reinery coke as in example IIb by
rotating 1 hour. Then 400 ml effluent from the hot-water
process tailings pond containing about 26.6% non-aqueous
solids was added and the suspension rotated for 10 hours.
A~out 300 ml aqueous tailings (1) was separated by screening. - :
The oil phase was rinsed twice by rotating for 15 minutes
wi.th 100 ml and 75 ml clear water respectively. About 140
ml aqueous tailings (2) were separated from the oil phase.
The results obtained are summarized below: :~
Separated Solids Loss on Bitumen Re- ~:
Tailings Content Ignition Covered from -
P6 400 ml effluent
and tar sands
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' 1 57.5 3 35
~, 2 37.9 7.45 37.7 g ; -
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~ 30About 68.15 g crude bitumen were separated contai- ;
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,, ning 23.7% water and 21.2% solids (including refinery coke).
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SUMMARY OF RESULTS
Example Refinery Coke Ml Effluent l~t. Tar Bitumen Re-
Nucleating Added Sand Added covered from
Agent Effluent
and tar sands
I 10.9 g 600 600 g 5108 g
IIanone (control) 400 400 g 16.75 g
IIb 10.9 400 400 g 41.6 g
III 6.55 400 200 g 41.1 g ~-
IV 4.36 400 400 g 37.7 g
By using more vigorous agitation-mixing to increase ~ .
inter-phase contacts, the processing time in the Examples
could be decreased considerably.
Optionally liquid hydrocarbon fractions such as
naphtha or kerosene could be added in small amounts (e.g.
1 - 2% wt. of the tar sand) to the tar sand as softening
., agent at an initial stage before contact with the effluent :.
(to accelerate the unitary organic phase formation). : - .
The method of this invention can be operated as .:. .
a side loop in a hot-water type of tar sands process, or ::
as an initial upgrading for feed to another process. :.
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