CA1115226A - Process for selective recovery of relatively metals free bitumen from tar sand using a halogenated aliphatic solvent - Google Patents

Abstract

A PROCESS FOR SELECTIVE RECOVERY OF
RELATIVELY METALS FREE BITUMEN FROM TAR
SAND USING A HALOGENATED ALIPHATIC SOLVENT

Abstract of the Disclosure A process for the selective recovery of tar sand bitumen from tar sands using a halogenated aliphatic solvent. The process provides for an inexpensive method for selectively removing substantially metal-free tar sand bitumen from tar sands. The bitumen so recovered, renders the same amenable to catalytic desulfurization and upgrading processes.

Description

~15i22~

~ackqr~al_____ he~ a~E~
1. Field of Invention ~
Deposits of tar sand occur at many locali.ties : .
throughout the world, however, the Athaba~ca Tar Sand deposit of northern Alberta in Canada repr~sent~ an e~t~mated xe~erve which exceeds the ccmbined proven oil reserves of the rest of ..
the world.
The tar sand originated from a deposit of ordinary ;~ :
oil that once lay buried ben~ath an ancient body of water, for example, a sea. The land area at the botto~ of the ea roBe and ; the water disappeared. ~he oil migra ed upward into the still-wet sea floor because the surface pressure wa~ insu~icient to :
hold the oil down. Because, the sea floor w~s still wet when :-~
the oil migrated upward, a fi~m of water and seashore clays, including metals, separated each yrain of sand from the oil.
The oil covered ths sand particles, ~rapping th thin ~ilm OI' ~ :
.
. water between the oil and sand particles. The oil in the tar ,: ' ~':

, ' ' .' " , .
. . -. ., , . . . - ,. ~. ~ ..

-z~

sand is no longer oil as we know it, because the lighter hydro-carbons evaporated long ago, due to the action of sunlight on the original oil. All that is left o the original oil are the heavy, carbon-rich hydrocarbons, plus sulfur and other impuri-ties, for example various metals, sand and water. The tar likeoil thus defined is in actuality a fonm of bitumen. Since the original upward migration of the oil through the sea bed, the eons have dumped boulders, gravel, sand, clay and the like atop the tar sand. However, to mine and process the tar sand using conventional methods costs at least three times more than it costs to drill and pump up natural crude. Thu3, because of the world~s dwindling supply o~ petroleum and energy related resources, it is highly desirable to extract oil from tar sand efficiently and economically. In accordance with the process dsfined and claimed herein, substantially metal-free tar sand bitumen is recovered from tar sand usiny a halogenated aliphatic solvent.
With the developing energy shortage~ the search for a workable and economicaLly feasible process for extracting oil in the form of bitumen fr~m tar a~d oil sand has intensified in recent years. Deposits of oil and tar sand occur at many localities throughout the world a~d represent a potentially large source of oil, howev~r, a~ of today a worka~le and econom-ically feasible process for extxacting bitumen from these tar sands ha~ not been disclosed.
Many processes for tar-oil sand development have been . - .proposed over the past few years. The processes include direct combustion, solvent extraction, water flo~ation and many varia- -tions o~ these processes to extract the oil in the form of bitumen. However, the extraction of bitumen from tar sands utilizing past processes has several disadvantage~, especially , ..

from an economic point of view. One disaclvantage of the pro cesses used in the past is a low racovery rate for the bit~men.
For example~ in a water flotation process only about 50 to about 70 percent of the bitumen is recovered ~rom the tar sand~
Another disadvantage in the case of a solvent ex-traction process of bitumen from tar sand, is that mo~t solvents u~ed in the past have a very strong affinity for the sand, and :: :
a significant percentage of the solvent is lost in the extraction and separation step of the process.
Both of the processes above additionally, extract .;~
undesirable components from the sand particles, for example, metals which contaminate various catalyst systems in a process to upgrade the bitumen to an oil product.
The tar sand her~in is charact~rized by individual grains of sand surrounded by thin film-~ of water which contain sand fines, minerals and metallic contaminants. The thin films of water are further enca-qed by bitumen, with the bitumen ~
partically filling the void~ between the individual grain~ of ~ :.
sand, forming a connecting link in ~he fonm of a bitumen bridge. ~ -The bitumen contains most o the organometallic compounds which create problems when the bitumen is ~rther processed over typical hydrotreating catalysts which are xeadily deactiva~e~
or poisoned by nickel and vanadium. Past attempts to extract bitumen from tar sands resulted in an alteration of the above described physical configuration and in some oil~wet~ing of . --. .. -- .. ...
solids; which additionally xesulted in oil-rich sludges and solids stabiliæed emulsions. The~;e sludges and emulsions result :.
in contamination of the bitumen or oil pha~3e wi~h SOlias aI~d water. Thus, it is very desirable to extract the ~itl~en ~rom 30 tar sand without rupturing the connate-water envelope containing ;

. -3- :

.
' .

containments, incl-ding metals, which surround the individual sand particles.

2. Description of The Prior Art Several methods have been propo~;ed in the past to ;~
extract tar sand bitumen 90 that it could be proce~sed into oil. For example, Dr. ~arl A~ Clark, a govarnment ~cienti~t worked out a process in the late 1940'8 known a~ the Clark proces~. The method includes stripping the overburden from the tar sand, mining the tar sand, a~d extracting the bitumen from the sand using steam and caustic ~oda. The bitumen is skimmed from the surface o~ the mixture. ~he methcd collect~ :
virtually all of the bitumen, howevex, the bitwmen contains about 35 percent water and minerals, including metal~.
Another proce~ ~ox xecovering bitumen rom tar san~
is set-forth in U. S. Patent No. 4,017~377, entitled Process And Fluid Media For Treatment v~ Tar Sands to Recover Oil, is~ued to Fairbank~, Jr. et al., on April 12, 1977. The reference discloses a process, stxucture, and aqueou~ bath ~or recovering oil from tar sand. ~n particular, the proce~ teache~
the ~teps of contacting the tar ~a~d with a diluent~ for example, ga~oline and/or naphtha; to reduce the internal fluid ~riction or viscosity of the oil layers surrounding each ~and parti~le, and then contacting the mixture with an aqueous bath having a slightly raised specific gravity and a wetting agent. The oil ~5 is then recovered using conven~ional me~hod~.
Another method and apparatus for ~eparating hydro-carbonaceous ~ubstances from mineral solids i8 set-forth in U S. Patent No. 3,941,679, entitled Separation Of Hydrocar~
bonaceous Substances Fr~m Mineral Solid3, is~ued to Ssnith et al, on March 2~ 1976. ~n partlcular, a solvent extractLon technique i~ employed wherein trichlorofluoromethane is used a~ the primary 4~
'. ' 2~1~

extraction solvent. The re~erence ~ d~xected to a proaess fox extracting bitumen ~rom ~oth t~x sand and shale~ Neithex o~ the above re~erences, ~owe~ex, d~sclo~s~ and teaches ~ process ~or recovery of relativel~ metals-~ree ~itumen xom tar sand.
The present inv~nt~on pr~vides a process ~or extract~n~
substantiall~ metal-free ~itumen ~rom tar s~nd composed o~
individual grains of sand surrounded ~ a thin film of ~at~r and further encased by an outer layer.of ~tumen, which comprises contacting said tar sand with a halogenated aliphatic solvent of the formula: f A ~
D ~ C J~ ~

B ~n ~.:
~herein n is an integer of from a~out 1 to a~out 20; and ~herein A,B, D and E are either alike or different, mem~ers selected from the group.consisting of h~drogen,..chlorine., bromine or fluorine and mixtures thereof, with.the provisio~ that at least onP of said A, B, D or E is chlorine, ~romine or ~luoxine; gently agitating said solvent, at ambient temperatures-and under atmospheric pressure, su~fi.cient to substantially diqsolve said bitumen in the solvent but without rupturing said fi~ o~ water, thereby forming two..phases.j;~ne.consisting es~eniial~y of said solvent..~ith.
bi~men dissolved therein and the other composed of said individual grain~ of sand carrying solely said film o~ water, separating said phases from each other, and then separating said ~ solvent from said ~itumen, to there~y obtain su~stantially metal- ..
~ ~ree bitumen.
T~e present invention rela$e to a process for extract-ing bitum~n ~rom tar sand ~y contacting said tar sand ~ith a halogenated aliphatic solvent, applying careful, gentle agitation, 30 -separating the halogenated aliphatic solvent and bitumen-from th~ tar sand and separating , 5Z~

. , , the solvent frcm the bitum~n.
The halogenated aliphatic solvents suitable for u~e herein preferably are of the formula:

~ A ~
D t c J E
~ B ,~n wherein n i~ an integer o~ from about 1 tv about 20, pre~erably -:
from a~out 1 to about 10; and wherein A, B, D and E are elthex alike ox different, members ~elected from the group ~n~sistlng of hydrogen, chlorine, bromine or fluorine and mixturee~ thereo, with the provision that at lea~t one o~ ~aid ~, ~, D or E is chlorine, brcmine or fluorine. Halogenated aliphatlc solvents suitable for u~e herein include:
Methylfluoride:
Fluoroform;
Chloro-1uoromethane;
.Bromo-~luoromethane;
~hlc:~ro-difluor~methane;
Chloro-trifluoromethane7 Ethylfluoride, Difluoroethane;
Bromo-~luoro0thane;
2-bromo-1, di1uoroethane;
Chloro-trifluoxoethane: -Di1uoro-di-chloro-ethane;
Trifluoro-di-chloroethane;
Tetra~luoro-di-chloroethane;
1,1~1,~ chloro-di-fluoroethanat ~:
: 1,1,1, trifluoroethane; :
1,2, ~i~luoxopropane;
:
1,3, Difluoropropane;

. .
-6- ~

L5;~

1, 2, 3, trif luoropropane:
1, bromo-2, f luoropropane;
1, br~mo-3, fluoropropane;
Di-chloro-mo~o-1uoromethane;
Tri-chloro-mono-~luoromethane;
Mono-cloxo-mono-bromo-mono-~luoromethane; : ;
Di-bxomo-mono-~luoramethans;
Tri-bromo-mono-fluorcmethane;
~etra-chloro-di-fluoxomethane;
Tri-bromo-mono-~luoroethane7 Tr i-chloro-ms~nc~- f luoroa thane;
Tetrachloro-mono-fluoroathane;
Tri-chloro-di1uoroe~hane;
Di-bromo-mono-fluoroethanet Trichloro-triiEluoro-eth2ne;
r-propy l f luor ide:
I o-propyl~luoride;
N-butylfluoride N-amyl1uoride;
~-hexyfluoride;
or ~h~ptylfluoride and mixtures thereof.
An especially desirabla halogenated aliphatic 901vent ~uita~le ~or u8e her~in, Freorl TF~ known under the U.P~A~C. nomen-clature system a~ trichlorotrifluoroethane, is one member o~ the i .
family o:E fluorocarbon chemical~ developed and commerically marke~ed by the DuPont~ Canpany under the well known trademark of Freon, origlnally~: Freon co}npound~ wcr developed as re~rlge::an~s, however, they presantly are widely u~ed a~ aerosol propellant~, solvents, cleaning agent~, fir~e extlngui~hing ag~nt~, dielectric fluid~, coc)lant~ and relatively ~table lis~uids~ Freon compounds .
are additiona}~y Ilon~lammable, chemically and thermz~lly inert, ~3L5Z~

chemically and physically pure and substantially nontoxic.
Previously, Freon TF has been used to remove oil, grease and dirt from objects without harm to metal, plastic or elastomeric parts. Table I below sets ~orth in greater de~ail some rather important properties of Freon TF.

.
Table 1 __ Molecular Wt. 187.4 Boiling Point at one atmosphere 117.6F (47.6C) Freezing Point -31.0~F (-3500C) Critical Temperature 417.4F (214.1C) Critical PressUre 495.0 PSIA (33~7 a~m) Density at 77F (25C) 1.565 gm~/CM3 ~atent Heat of Vaporization at boiling point 63.12 BTU/lb Vi~co~ity at 70F (21.1C) 0.6g4 centipoi~es Surface Ten~ion at 77F (25~C) 19.0 dynes/cm Freon TF i~ a pure, ~table chemical compound which is a clear, dense, colorle~ liquid having a faint ~olvent odor.
Normally, be~ora bitumen can be 0xtracted r~m tax sand, the overburden of up to 150 feat o~ clay, 3an~, gravel and boulders has to be stripped ~r~m atop the tar ~and and after the tar sand is expo~ed, it i~ mined and transpor~ed ~o extrac-tion apparatu~. It has been detenmined t~lat approximately twotons of tar sand will produce one barrel of oil. Thus, mininy and extraction apparatus tend~ to be extxemely larga. Tar sands will normally contain from about 100 PPM to about 500 PPM o metals, generally about 200 PPM to about 400 PPM of metals. :tn this process, the bitumen ~o recovered wlll contai~ from about 1 PPM to about 50 PPM o~ metaLs.
In the claimed process, ~he mined t~r sand a~ defined above is mixed with a halogenated aliphati~ ~olvent, as herein defined in an extxaction vessel, ~or example, a revolving rotary drum to form a s~urry, The halogenated aliphakic s~lvent i8 generally mixed with ~he tar ~and at a volume ratio o fr~m about ' "

--8-- .
' .

0 . 5: 1 to about 5: 1, preferably from about 1: 1 to about 3: 1 ~or about 0.5 minute to about 60 mi~utes, preferably from about 1 minute to about 30 minutes. Preferably the mixing and extrac-tion qteps take place at ambient temperatures and under abmos-5 pheric pressure. As a result of such action, ~he halogenatedsolv~nt extracts the bitumen frem the tar sand by di~301ving th~ bitumen; at the ~ame time, since the mixi.ng herein is gentle, the water envelope surrounding the ~and and containing most of the metals and other contaminants i~ not ruptured. The tvtal resul~ing slurry i3 naxt pumped into separatlon cells whi~h can be several storia high and as much as 70 feet a~xo~s ~ a typical process.
The extracted bitumen dissoLved in the halogenated aliphatic solvent i~ then 3ep~rated from the sand (carr.ying it~
.ï5 water envelope sub~tantially intact) in any conv~ntional manner, for example, by draining, ~iltration etc. Recovery o~ the halo-genated aliphatic solvent from the aolution of solvent and bitumerl can easily b~ effected by subjecting the solution to distillation, ~ince the boiling point of the solvent i~ much lower then that o~ the bitumen. 5uch di~tillation c:an be e~Efacted, for example, at a temperature oi~ about 48C to about 92C, preferably about 60C to about 80C, and a pressure o~ about 1.47 to about 300 pound~ per square inch gauge (about 1.04 to about 21.09 kilograms per square cent~neter), preferably about 14.7 to about 100 pounds per ~quare inch gauge (about 1. 04 to about 7 . 03 kilograms per square centimeter). Accordingly~ the bitwmen so ; ~ .
recovered is not contaminated with the solids and other contami-r~ants pre~ent in the water envelope surrounding the tar ~and charge and recovery procedures are not complicated ~y the pre3ence o free water that would have been present had the watar envelope been punctured.

_9=

.. . .

52~2~
Description 0,f Preferred,Em,bodiments A 100 gram sample o~ Athaba~ca tar ~a~d particle~
containing 12 grams of bitumen and 299 PPM of nickel and 52 PPM of vanadium, sub~tantially all of which metal~ were contained in the water envelope suxrounding the individual tar sand par-ticles, was contacted under gentle agitation for lO minute~ with 200 ml of trichlorotrifluoroethane at ambient temp~rature and ambient pressure. The re~ulting mixture was permitted to come to rest. Solid tar sand particle~ ~ettled to the bottom of the mixture, with the remainder being escentially tar sand bitumen dis~olved in trichlorotrifluoroethane. No noticeable watar was present~ The solution wa9 recovered by filtration. The tar sand originally black, was found to be light-mediwm brown in color. ~he solution wa9 subjected to distillation at 150F
(65.56C) and ambient pressurs to remove trichlorotrifluoro-ethane therefrom. There was recovered 10~8 grams of ~ltumen containing 30 PPM oi nickel nd 7.a PPM of vanadip~n.

' '~
'::
.' ' ,, ''.
. ., .' ~
-10~
.

.: .

Claims (17)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process for extracting substantially metal-free bitumen from tar sand composed of individual grains of sand surrounded by a thin film of water and further encased by an outer layer of bitumen, which comprises contacting said tar sand with a halogenated aliphatic solvent of the formula:

wherein n is an integer of from about 1 to about 20; and wherein A, B, D and E are either alike or different, members selected from the group consisting of hydrogen, chlorine, bromine or fluorine and mixtures thereof, with the provision that at least one of said A, B, D or E is chlorine, bromine or fluorine; gently agitating said solvent, at ambient temperatures and under atmospheric pressure, sufficient to substantially dissolve said bitumen in the solvent but without rupturing said film of water, thereby forming two phases, one consisting essentially of said solvent with bitumen dissolved therein and the other composed of said individual grains of sand carrying solely said film of water, separating said phases from each other, and then separating said solvent from said bitumen, to there obtain substantially metal-free bitumen.

2. The process of claim 1 wherein n is an integer of from about 1 to about 10.

3. The process of claim 1 wherein the halogenated aliphatic solvent is a member selected from the group consisting of:
Methylfluoride; Fluoroform;
Chloro-fluoromethane; Bromo-fluoromethane;
Chloro-difluoromethane; Chloro-trifluoromethane;
Ethylfluoride;

Difluoroethane;
Bromo-fluoroethane;
2-bromo-1, difluoroethane;
Chloro-trif1uoroethane;
Difluoro-di-chloro-ethane;
Trifluoro-di-chloroethane;
Tetrafluoro-di-chloroethane;
1,1,1, chloro-di-fluoroethane;
1,1,1, trifluoroethane;
1,2 Difluoropropane;
1,3, Difluoropropane;
1,2,3, trifluoropropane;
1, bromo-2, fluoropropane;
1, bromo-3, fluoropropane:
Di-chloro-mono-fluoromethane;
Tri-chloro-mono-fluoromethane;
Mono-cloro-mono-brono-mono-fluoromethane;
Di-bromo-mono-fluoromethane;
Tri-bromo-mono-fluoromethane;
Tetra-chloro-di-fluormethane;
Tri-bromo-mono-fluoroethane:
Tri-chloro-mono-fluoroethane;
Tetrachloro-mono-fluoroethane;
Tri-chloro-difluoroethane;
Di-bromo-mono-fluoroethane;
Trichloro-trifluoro-ethane;
N-propylfluoride;
Iso-propylfluoride;
N-butylfluoride;
N-amylfluoride;

N-hexyf1uoride;
or N-heptylfluoride and mixtures thereof.

4. The process of claim 1 wherein the haloganated ali-phatic solvent is trichlorotrifluoroethane.

5. The process of claim 1 wherein the tar sand comprises sand particles surrounded by a thin film of water and contami-nants, which are further encased by bitumen.

6. The process of claim 1 wherein the tar sand comprises sand particles surrounded by a thin film of water and metals, which are further encased by bitumen.

7. The process of claim 1 wherein the tar sand comprises bitumen which is impregnated with metals, fines and other contaminants.

8. The process of claim 1 wherein the halogenated ali-phatic solvent and tar sand are mixed in a volume ratio of from about 0.5:1 to about 5:10

9. The process of claim 1 wherein the halogenated ali-phatic solvent and tar sand are mixed in a volume: ratio of from about 1:1 to about 3:1.

10. The process of claim 1 wherein the halogenated ali-phatic solvent and tar sand are mixed for about 0.5 minute to about 60 minutes.

11. The process of claim 1 wherein the halogenated ali-phatic solvent and tar sand are mixed for about 1 minute to about 30 minutes.

12. The process of claim 1 wherein the halogenated ali-.
phatic solvent and bitumen are separated from the sand by:
filtering.

13. The process of claim 1 wherein the halogenated ali-phatic solvent is stripped from the bitumen by distillation.

14. The process according to claim 1 wherein the tar sand comprises from about 100 PPM to about 500 PPM of nickel and vanadium.

15. The process according to claim 1 wherein the tar sand comprises from about 200 PPM to about 400 PPM of nickel and vanadium.

16. The process according to claim 1 wherein the metals include nickel, or vanadium, and mixtures thereof.

17. The process according to claim 1 wherein the ex-tracted bitumen contains less than about 50 PPM of metals.