CA1293943C - Microwave separation of bituminous material from tar sands - Google Patents

Abstract

ABSTRACT
A new process has been developed to separate the bituminous fraction from tar sand (oil sand) using selected microwave frequencies. Frequencies which are preferentially absorbed by water have been found to effect separation. General heating of tar sands by microwaves, which are not strongly absorbed by water does not produce any apparent separation. Especially preferred are microwaves of frequency 947, 950 and 953 MHz, which produce fairly clean separation into asphaltic and mineral fractions. 1500 MHz has also been found to be an operable frequency although less preferred.

Description

~3~ ~3 ~IICROWAVE SEPAR~TION OF BITUM`~N011 ~rrF.~I~r. F~M rr~R S~W~, This invelltioll relates t:o treatme~t o~ ml~tures of hituminous, aqueolls, arld mineral matter of the tyE~e commonly referrecl to as tar ~a~ds, by electroZna-Jrletic frequenc:ies of the type commorlly referred to ac;
icrowaves.
It :is an ohject of the invention to prov:ide a method of separating tar sand into two fractions, one fraction containing bituminous matter, the other fraction containing mineral matter. These two fractions are not necessarily absolutes, the bituminous fraction will contain a greater proportiorl of bituminous matter than the original tar sand, while the mineral fraction will contain a greater proportion of mineral matter than the original tar sand. Desirably there will be no apparent bitumen in the mineral fraction, and no apparent mineral in the bitumen fraction.
Microwaves are generally deEined as that portion of the electromagnetic spectrllm having fre~uencies greater than those of radio waves and less than those of in-frared waves. It is generally said that microwaves have frequencies ranging fLom 300 MHz (300 megahert2) to 300 GHz (300 gigahertz), corresponding to wavelenyths of 1 metre to 1 millimetre, respectively, althouyh 100 MH~
(3 metres) ancl 1000 GHz (0.8 millimetre) are sometimes also quoted as limits.
Applicant has discovered that by applying microwaves of selected wavelenyth to tar sands separation of bituminous and mineral fractions can be achieved.
Tar sand also known as "oil sand" is understood -to mean in -this application a naturally occurring mi~ture of tar, wa-ter and mineral matter, which is usually sand but may contain clay particles. The -tar is bituminous in nature and typically compr:Lses from about O to about 18% by weight of the mixture, water typically comprises about 2 to about 12% by weight Oe the mixture, while miner~-ll matter typic-a:Lly cc)mprises abollt 83~ by weil~JIIt of ~he ml~turt?, ~ar:iatiorl F~om these e:igllres mcly he obset~ed. The mirleral ~natter lrlc~ cles sarld grc~ s arld fines~ The sand gra:lns are l~el:ieved to ~orrn a Spc:~C~.?
~illincJ arraIlgelllellt, wettecl by a wacer film ~ormincJ an envelope aroun~ each ~raln, w:ith a hitumen fi]m surrounding the wetted sand grains and partly filliny the residual void volume, tlle rest of the voicl volume 1s filled ~ith conna-te water and sometimes some gas.
Mineral fines when present are believed to be in the ~ater envelope.
DESCRIPTION OF THE PRIOR ART
General applications of electromagnetic waves to tar sands, oil shales and coals are known. Radlo waves may be applied directly, or as a fluctuating electric or magnetic field, or by incluction heating where an electric current is applied to generate another electric current in the matexial to be treated [a5 a primary coil current in a transformer generates a secondary coil current]. All these can be viewed as applicatl~n of electromagnetic waves loosely termed of "radio"
frequency. General use of such frequencies for heating tar sand or oil shale in situ is taught by Rowlancd in U.S. Patent 4,135,579 and Dauphine in Canaclian Patent 1,105,376, which utilize frequencies between 100 kilohertz and 100 megahertz, for general heating of oil shales. The Fishers in Canaclian Patents g94,694, 994,695 and 1,105,3~6 teach similar treatment o~ tar sand by induction heating using alternating current of unspecified Erequencies, except that it is suygested that normal 60 cycle AC could be used.
Radio ancl microwave frequency heating oE oil shales, tar sands and coals to liqueEy, volacilize, ancl pyrolyse the bituminous or organic co~lponent is well known. Microwaves are used to retort such materials by Hodge in U.S. Patent 2,542,028, Knapp in M.S. Patent 3,449,213 and 3,560,347, Stone in U,S. Patent 3,503,865, Wallace in U.S. Patent 4,118,282, Dumbaugh et al in ~293~3 Canadian F'atent 1,108,081, Wall Ln U.~. Patenl:
~,376.034, Balint et a.l ln ~.S. Patent ~,419,21~, general freqllencie~ are t~ught from 20 MHz t:o 1000 GHz, specif.ic :Erequencies app:lied were 20 MH~æ. (Hodge), 0.~ to l.Q GH~ (Ballnt), 0.9:l5 GHz (Wall, Balint), 0.9 to 2.5 GH~ (~alint), 2.~5 ~Hz (Wallace, Dumbaugh, Wall,) 5.8 ~Hz (Balint), Knapp and Stone are indifferent to the frequency applied a~ long as it is above lOOO MHZ (l GHz) (Stone) or allowed by the FCC (Knapp). Ergun in lO U.S. Patent 3,463,310, teaches application oE microwave heating to the mineral component of coal to change its magnetic prcperties to allow separation by magnetic means over ~ frequency range of 0.4 to 10 GHz.
Nadkarni, in U.S. Patent 4,408,999 treats oil shale or coal or the like in an acidic slurry with frequencies in the lOO KHz to lOO GH~ range with l to 3 GHz preferred, this assists the solutlon oE the mineral component in the acidic slurry.
SUMMARY OF THE INVENTION
In a broad aspect the invention is directed to a process of physical separation of tar sand comprising bituminous, mlneral and aqueous components into upper bituminous and lower mineral fractions. The improvement provides exposing the tar sand to microwave radiation in the absence of indus-trial solvent, of a frequency strongly ab~orbed by water at a level sufEicient to allow the tar sand to separate by gravity into upper bituminous and lower mineral fractions. The upper bituminous fraction comprises a greater proportion of bituminous matter than the tar sand, and the lower mineral fraction comprises a greater proportion of mineral matter than the tar sancl. The microwave frequency is selected from the group consisting of about 947 MHz, about 950 MHz, about 953 MH~. and about 1500 MHz. The microwave frequency may be selected from the group consisting of about 947 MH2, about 950 MH~, and about 953 MHz, or the miorowave frequency may be about l500 MHz.

339'~3 I~ anottle:r aspect tht? inverltlorl i~ I.rected to a proces3 of phy~:ical separation tar ~ancl colnp:r~ rly bit~lmi~ , mineral and aqueous colIlporlents .into upper bitumlnous and lower mlneral fractions~ The imprcJvernent provides exposlng the tar sand in the ahsence o~
:industr.ial ~olvent to mLcrowave rac.liation of a erequency s-tron~ly absorbed by water at a level suEEicient to allow the -tar sand to separate hy gravity into upper bituminous and lower mineral fractions. The upper bituminous fract:ion comprises no apparent mineral matter, and the lower mineral fraction comprises no apparent b.ituminous matter. The microwave :Erequency is selected from the group consisting of about 947 MHz, about 950 MHz, about 953 MH~ and about 1500 MHz. The microwave frequency may be selectec~ from the group consisting of about 94~ MHz, about g50 MH2, about 953 MHz, or the microwave frequency may be about 1500 MHz.
In a third broad aspect the invention i5 directed to a process of physical separation of tar sand comprising bituminous, mineral and aqueous companents into upper bltuminous and lower mineral fractions. The improvement provides exposing the tar sand to microwave radiation in the ab~ence of industrial solvent to allow the tar sand to separate into upper bitumlnous and lower mineral Eractions. The upper bituminows fractian comprises a greater proportion oP bituminous matter than the tar sand, and the lower mineral ~raction compri~es a greater proportion oE mineral matter than the tar sancl.
The In:Lcrowave frequency is selected from the group 30 consisting oE about 94~ MHz, about 950 MH~, about 953 MHz and about 1500 MHz. The microwave frequency may be selected Erom the group consisting o~ 947 MHz, abou-t 950 MHz, and about 953 ME~z, or the microwave Erequency may be about lhOO MH~. -In every aspect oE the invention the microwave radiation may be generated by a magnetron, optio:nally transmitted to the tar sand throuyh connectiny means selected Erom coaxial cables and wave gwides to supply 3~i~3 all electI~nic arltellrla type gellel~a t~r itl C~llt:at:t with said tar ~allcl.
Tt is hyE)~thesisecl by appli.cant that the ~e:Le(t:ed microwaves are preferelltia:lly absorbecl by both the water enve:Lope o:F the sanc1 grains and the connate water be-tween -the sand grains (if presellt), raisiny the water temperature fairly rapidly, opening the bitumen envel~pes as it does 50 . The hitumen and mi.neral yrains and Fines are then separate an1 further heating allows the grains ancl fines to settle while the bitumen rises.
Applicant merely advances this view as a hypothesis and is not bouncl thereby.
DESCRIPTION OF PREFERRED EMBODIMENT
Tar sands were -treated at various frequencies in microwave ovens of standard commercial -type, in glass, plastic or metal containers, in some cases the operatin~
microwa~e yenerator (magne-tron) was replaced by another magnetron of different Prequency.

The microwave uni-t (oven) was rated as 950 MHz and 500 watts, 20 ounces (570 g) of bitumi.nous tar sand was heated in a glass container.
TIME INTERIOR EXTERIOR REMARKS
TEMP. TEMP.
1.5 minutes 160 F 68 F
TIME INTERIOR EXTERIOR REMARK~

2 minutes 205 F 100 F

3 minutes 390 F 110 F Separa-tio:n has commenced

4 minutes 542 F 205 E' Great amoun-t of steam

5 minutes ~600 E' 300 F Separation complete There is sancl on the bot-tom cf the container, liclht in colour with no visible water. Above the sand are ~everal layers :ranging from medium yellow to very heavy black material of asphalt like appearance.
EXAMPLE ?
The magnetron usecl was rated as ~50 MHz, ancl 1500 wa-tts, a TV type coaxial cable was connected to the magnetron at one encl and -to an elec-tronic antenna type 93~43 qenerator at the otherJ the gellerator was. insexM~ d i.nto a 5 CJallOn ('~.0 Iltre) Ille-tal hucket fllll of b1tUm:irlC1~:lS
tar ~a~lcl anl the ma~rle t:ron swi-tched on .
T I ME I NTER I ûR R~.MAR~S
TEMP .
0 minutes 58 F
1 minutes S7 F
2 min~l-tes 73 F
3 minute6 91 F
lQ ~ minutes lOS F
5 minutes 1~6 F slurry beginning to soften

6 minutes 173 F
~ minutes 188 F operator notes discomEor-t 3 minutes 243 F
9 minutes 287 F bu~ket too hot to touch, operator notes acute discomfort, a can of water neaxby becomes extremely warm, heatiny was discontinued.
The bucket on cooling to 66 F was about 1~3 rd full although full a-t be~inniny of heating. The bucket contained three layers - a top layer of black material resemblin~ partially set asphalt in appearance and smell, below this a ~econd layer of yellowish rankish sme:Lllng mixture, below this again a thircl layer of a mixture of sand, water, and other uniden-tified matter.
A sample of this thircl layer was allowed to settle, the sediment appearecl largely sand and other mineral ma-t-ter and to have no apparent rust present. 5ubstantially identical results were obtained when a wave guide was substituted for a Goaxial cable, it was noted that the rate o~ heating was mar~lnally enhanced.

Several tests were carried out on solid and semi-soli~ bituminous tar sands as found around Fort McMurray, Alberta, using a magnetron rated a-t 500 watts and ~50 MHz as in Example 1. It was :Found that 4 minutes was suffi~ient to hea-t the samples to 500 F, separate the slurry into mineral and bituminous fractions and to drive off water present -to the extent ~33~3'~3 -that no vi~lble water was. apparent I:rl the t~ eated ~esidllt?.
These exper:lmerlt3 were repeatec1 wlth simllar magnetrons ra-ted at 94~ MHz, alld 953 MHz, the resll:L-t~
~or practical purposef3 were ind.i.stingllishable from those a-ttail~ed at 950 MHz.
EXAMP~E 4 A further test was performed as in Example 1 us;ng a maynetron rated at 1~50 MHz ancl 500 wat-ts, the sample o took 8.g minutes to achieve 500 F, no apparent separation was noted.

A further test was performed as in Example 1 using a magnetron ra-ted at 650 MHz and 500 watts, this produced a -temperature of about 1200 F in less than 2 minutes, boiling the oil component to produce a slurry but without apparent separatlon.
EXAMPI,E 6 A further test was performed as in Example 1 using a magnetron ratecl at 2500 MHz and 500 watts, a plastic container which melted without comparable heatiny or apparent separation of the contents, a repeat using a glass container resulted in the glass heating, but again neither comparable heatiny nor apparent separat:Lon o:E
the contents was notecl.

A further test was performed using a microwave o-~en with a magnetrorl rated at 1500 MH~ and 500 wa-tts, samples of about 100 ml of tar sand were treated, .it was notecl that after about 22 seconds exposu:re, the bitumen envelopes opened releasing small amounts of water, which apparently evaporated rapidly, caus:Lrlg sand grains -to become visible, after a Eurther exposure of about 46 seconds the bltumen began to liquefy. ~pplicant Found this frequerlcy less satisfactory for separation as the bitumen had a tendency to decompose, vola-tilize or crack under these conditions, i.e. the resultiny product had undergone chemical change.

1~

~Z9~9~3 A Eurther series of magnetrorl~ ~ar:iou~].y rated he-tween 8~0 M~Iz and l120 MH2. were tested Fol:low:lrl~J the procedllre of Example 1, withollt noting any appareIlt separation ~ the tar sand into bituminolls and m:ineral fractions.
~ t was observed genera]ly -th~:lt heatincJ was more rapid at the lowe~ erecJueIlcies and that more time was reqllirecl Eor heating a-t the higher Erecluerlcies -to achieve -the sdme -temperatures.
Applicant founcl that the mineral fraction ls usually fairly clean ~and, and coulcl probably be used untreated in industrial applications.
As would be noted by those skilled ln the art that the temperatures as measurecd appear too high to achieve the results indicated. Water would almost certainly cavitate, probably explosively, if heated as rapidly above the boiling point as indicated, and certainly there should not be residual water as indicatecl in experiment 2. As water has a high specific heat as well as a high heat of vaporization, it would seem probable that the temperature measuring device was itself being heated by the microwaves, so registering a temperature greater than its surroundings.
The ex.pressions about 947 MH2, 950 MHz, 953 MHz, and about 1500 MHz, mean tha-t the particu:Lar device usecl was rated at these output frecluenc~s,, a.; wou:ld be unclers-tood by -those skilled in the art. There are five causes of -frequency output variation. As long as the rated magnetron ou-tput lies within a designated ~requency band, it will often be indicated as having the desiynated frequency of that hand, typically those allocatecl by the E'CC centred nominally at 915 MHz, 2450 MHz, 5800 MHz and 22000 MHz, with varying alloca-ted handwiclths. Further frequency variation is due to magnetron dimensional variation causecl by ~anufacturiny tolerances, theoretical quality of resonance (bandwidth) of the magne-tron, quality of ~esonance ~bandwidth~ as modified by the circuitry used ~ith the ma~netron, althoucJh thes~ are us~lally small of the order oE ~ or so, ~nd may be less. Another cause of freqlleTIcy variation is quality of resonance (bandw:iclth) as fllr-ther mocl:i:eied by the racliofrequency (microwave frequf.~ncy) iinpedanc~ of the device the m~gnetron is used to :irradia-te.
As discussed by Syoicho Saito, In an art:Lcle re~iewed in Microwave Eneryy Applications Newsletter, Vol. IX, Sept.Oct. 1976, ~ 5, pp. 5-6, the RF (microwave frequency) impedance of a mlcrowave oven is chosen from the Reike diagram of the maynetron, which does not include all the magnetron characteristics, and -the RE' impedance locus is complicated. Abnormal operation of the magne-tron may result e~pecially at the high efEiciency region of the Rieke diagram. Moding, oscillat.ion stop, wide osclllation spectrum, side band radiation are all possible, anode current also affects output frequency of the magnetron. The rated output Erequency of a magnetron is therefore a loose indicative ideal of the outpu-t frequency rather than an exact description of the output, as would be understood by those skilled in the ar-t.
As those skilled in the art would realise these preferred details can be subjected to substantial variation, modification, change, alteration, ancl substitution ~ri-thout affecting or modifying -the Eunction oE -the especially preferrel illustrated emboliment.
Althouyh embodiments of the invention have been described above, it i5 not limited thereto, and it will be apparent to persons ~killed ln the art that numerous modificat:ions and variations Eorm part of the present invention insofar as they do not depart Erom the spirit, nature and scope of the claimed and described invention.

..~ i

Claims (11)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In a process of physical separation of tart sand in comprising bituminous, mineral and aqueous components into upper bituminous and lower mineral fractions, the improvement comprising exposing said tar sand to microwave radiation in the absence of industrial solvent, of a frequency strongly absorbed by water at a level sufficient to allow said tar sand to separate by gravity into upper bituminous and lower mineral fractions, wherein said upper bituminous fraction comprises a greater proportion of bituminous matter than said tar sand, and said lower mineral fraction comprises a greater proportion of mineral matter than said tar sand, and said microwave frequency is selected from the group consisting of about 947 MHz, about 950 MHz, about 953 MHz and about 1500 MHz.

2. The process of claim 1, wherein said microwave frequency is selected from the group consisting of about 947 MHz, about 950 MHz, and about 953 MHz.

3. The process of claim 1, wherein said microwave frequency is about 1500 MHz.

4. The process of claim 1, wherein said microwave radiation is generated by a magnetron.

5. The process of claim 1, wherein said microwave radiation is generated by a magnetron and transmitted to said tar sand through connecting means selected from the group consisting of coaxial cables and wave guides to supply an electronic antenna type generator in contact with said tar sand.

6. In a process of physical separation tar sand comprising bituminous, mineral and aqueous components into upper bituminous and lower mineral fractions, the improvement comprising exposing said tar sand in the absence of industrial solvent to microwave radiation of a frequency strongly absorbed by water at a level sufficient to allow said tar sand to separate by gravity into upper bituminous and lower mineral fractions, wherein said upper bituminous fraction comprises no apparent mineral matter, and said lower mineral fraction comprises no apparent bituminous matter, and said microwave frequency is selected from the group consisting of about 947 MHz, about 950 MHz, about 953 MHz and about 1500 MHz.

7. The process of claim 6, wherein said microwave frequency is selected from the group consisting of about 947 MHz, about 950 MHz, about 953 MHz.

8. The process of claim 6, wherein said microwave frequency is about 1500 MHz.

9. In a process of physical separation of tar sand comprising bituminous, mineral and aqueous components into upper bituminous and lower mineral fractions, the improvement comprising exposing said tar sand to microwave radiation in the absence of industrial solvent to allow said tar sand to separate into upper bituminous and lower mineral fractions, wherein said upper bituminous fraction comprises a greater proportion of bituminous matter than said tar sand, and said lower mineral fraction comprises a greater proportion of mineral matter than said tar sand, and said microwave frequency is selected from the group consisting of about 947 MHz, about 950 MHz, about 953 MHz and about 1500 MHz.

10. The process of claim 9, wherein said microwave frequency is selected from the group consisting of about 947 MHz, about 950 MHz, and about 953 MHz.

11. The process of claim 10, wherein said microwave frequency is about 1500 MHz.