US2790750A - Recovery of oil from bituminous sands - Google Patents

Description

Ap 30, 1957 R. T. EYRE RECOVERY oF on. FROM BITUMINous SANDS 2 Sheets-Sheet 1 Filed June 17, 1954 INVENTOR. ROBERT T. EYRE Buhwsgmwg ATT-ORN Y olmm April 30, 1957 R. 1'. EYRE '2,790,750

RECOVERY oF OIL. FROM BIfrUMINoUs SANDS Filed June 17, 1954 2 Sheets-Sheet 2 1N V EN TOR.

ROBERT T. EYRE ATTORN 18 through which the pulp passes to the agitator 11. The agitator comprises a tank 19 in which is disposed one or more shafts 20, having a greater number of radial arms 21 than the shafts 14 ,of the pug mill. Shafts 20.are rotated at a high speed by a motor 22 to effect vigorous mixing of the pulp with cold water. A water supply 23, through which a relatively large volume of water can be fed, is located adjacent the inlet 18. The tank 19 has an outlet 24 near the top, from which the aqueous dispersion of tar sand is passedto the settling zone 12.

The inclined conduit 12 which functions as the separating zone may have various cross-sectional shapes, but is shown in Fig. 2 in the form of a circular pipe. It is important` that the bottom surface of the conduit be inclined at an angle within the range of 2835, more preferably 30-31". If the angle of inclination is less than 28, the sand and tar fed from pipe 24 will not flow properly down the incline, while with the angle greater than 35 the material tends to flow too fast to separate properly. Conduit 12 is resiliently supported, and a vibrator 27 is provided so that the conduit may be continuously vibrated to aid in maintaining ow of the sandu layer. The vibrator is shown in the drawing as comprising a motor driven eccentric shaft, but it may bev a solenoid-operated electrical vibrator or any other form of apparatus suitable for subjecting conduit 12 to vibrations.

As a further aid in facilitating llow of the sand along the bottom of conduit 12, it is preferable to provide a series` of water injection lines y28 through which slow streams or trickles of water may be introduced into the flowing sand. This prevents the sand from packing and maintains itin a more or less .quicksand state. It also aids in effecting separation of the oil from the sand layer.

Along the bottom of conduit 12 adjacent its downstream end, means are provided for trapping the sand so that it can be withdrawn separately. As shown in Figs. 1 and 2, such means may comprise lines 29-a and 29-b containing suitable valves 35a and 35-b adapted to regulate the rate of withdrawal of the sand. Within the conduit 12 bales 39-a and 39b are positioned adjacent the downstream sides of sand outlets 29-a and 29-b to aid in trapping the sand. While the apparatus is illustrated in Fig. l with two sand outlets, it will be understood that the operation may be conducted with only onesuch outlet or with more than two outlets if desired.

In order to prevent the sand from packing rmly in draw-off lines 29-a and 29-b and to facilitate its withdrawal through valves 35-a and 35-b, water supply lines 42-a and 42b, having valves 43-a and 43-b, are provided. Water is slowly'introduced through these lines into the sand just above valves 35a and 35-b to maintain it in slightly expanded state so that its removal through the valves can be more readily regulated. 4 The sand thus removed is disposed of in any manner desired.

Beyond the last sand draw-off line, the apparatus is provided with means for collecting and withdrawing the tar layer as a separate stream. Conduit 12 has two downwardly extending chambers 25 and 26 at its lower end, which function as separate sections from which the oil and water are drawn off respectively. A bathe' 43 extends upwardly from the junction of chambers 25 and 26 preferably to a height slightly above the top of baie 39-b. The oil passes over bale 39-b as a thin layer and flows along the curved bottom side of the conduit into chamber 25 where it is collected. A valve 41 is provided at the bottom of chamber 25 for removing the oil and passing it to a suitable receiving tank (not shown). A water line 30 containing valve 60 is connected with chamber`25 at a level above the normal oil level, so that a slo w stream of water can be introduced above the oil. This is Vimportant in preventing clay or silt from settling in chamber 25 andthereby contaminating the oil which is withdrawn frornlit. The water introduced through line 30Ncauses aslow upward ow which carries the clay or siltover baille 43I into chamber 26 along with the main tlow of water. By this arrangement, practically all of the clay or silt that was in the bituminous sand fed to the system is contained in the water layer which flows down into chamber 26.

The water layer from the separation zone is withdrawn through valve 46 at the bottom of chamber 26 and is sent through line 37 to a settling pond'38, indicated diagrammatically in Figl by dashed lines. A sufficiently large settling pond will provide adequate time to allow most of the clay or silt to settle from the water which can then be re-used. The supernatant water is recirculated through the systemby means of line 48 and pump 49, the bulk of it flowing through line 34, cooler 36, valve 54 and line 23 to agitator 11. The purpose of including cooler 36 is explained hereinafter. The smaller amount of water required for the pug mill 10 is supplied by means of line 53, valve 55 and line 17. The slow ow of water for injection lines 28 on the lower side of conduit 12 is provided through line 56 and valve 57, while the water for sand draw-off lines 29-a and 29b and for chamber 25 is supplied through line 40.

Fig. 3 illustrates a more simplified form of apparatus which can be utilized as the separating zone for the present process. The separator in this case comprises an inclined conduit 112 which terminates in a downwardly extending section which is divided by baille 143 into two chambers and 126. The conduit is provided with water inlets 128 adjacent its bottom wall for introducing slowistreams of water at spaced points into the sand layer as previously described, and with a vibrator 127. In this case the downwardly extending section functions both as a sand trap and as a collector for the oil layer. As shown in Fig. 3, the feed mixture, which is introduced through line 124 from agitating apparatus as previously described, straties into `the three layers; and the sand layer passes from the inclined conduit downwardly into chamber 125 while the oil layer accumulates above the sand and passes over baffle 143 into the other chamber 126. Chamber 125 has an outlet valve 135 for regulating the rate of sand removal. Water may be fed slowly through line 132 and valve 133 into the sand at the base of chamber 125 in amount sufficient to prevent packing of the sand. The oil collecting chamber 126 is provided with a water line 129 containing valve 130 for introducing a slow stream of water that will cause an uptlow and preventv settling of clay or silt into the oil layer. The water layer, containingy substantially all the clay or silt, is removed from a higher level by means of line and valve 146.

There are several important conditions that should be established for successful or most elicient operation of the process according to the invention. In the pug milling operation only a minor amount of water should be present-for example, 5-25% based on the mixture, with about l0-15% being preferred-and the mulling should be done at a temperature above 50 F. but preferably below 100 F. The recommended procedure is as follows: Tar sand in its natural state, broken into particles of size suitable for handling, is placed in the pug mill 10 and water containing a detergent is gradually added up to the desired minor amount. The detergent can be any of the well known surface active agents which are commercially available for detergent use. Its purpose is to aid in breaking the lm of oil from around the sand grains, but its presence is not essential for successful operation of the process. The mixture at ordinary temperature is mulled in the pug mill without any heating other than that which occurs due to working of the mass. The temperature of the mass typically may rise to about 80 F. It is important that the mixture be mulled for a time Vsutiicient to break the oil lm from around the sand grains, which time can be ascertained bythe appearance of clean grains of sand in the mass and the presence of discrete oil particles. At this stage the mixture should be discharged from the pug mill, since further milling will tend to cause the oil to stick to the sand grains and makev it impossible vto' 'attain 'the desired, separation.

In the agitator i11 the pulp obtained from thefr'nilling step is vigorously mixed`with a largevolume ofgcold water, generally yat least ten times its volume being used. A typical rproportion is volumes of water for each volume of the pulp. It isA particularly important here that the temperature of the water be suiciently low so that the resulting mixture will have a temperature between freezing and 50 F. AI have found that at temperatures below 50 F., the oil or tar is in a more or less plastic condition whereby it will still flow and yet have little or no tendency to stick to the sand grains` or the equipment. Under these conditions it is capable of stratifying in a layer and'moving through the system. Hence such low temperature condition greatly improves the separating efficiency of the operation.v

Thecold mixture at a temperature below 50 F. is

passed from rthe agitator to lthe separating zone and,

should be fed gently beneath' the water level near the lower side of the inclined conduit in order to minimize agitation therein. `As previously stated, an important factor is the angle of inclination of the conduit, or at least of its bottom wall,'which angle should be in the range of 28-35, preferably about `30-3lf The sand and tary accumulate along. the bottomwallot the conduit; and with the"aid"of"the`vibrations t'dwhich theenduit is subjected andv by virtue of its' angleof inclination, they flow along the wall at a rate which permits the oil particles to'stratify as alayer above the sand. This is aided, as previously described, by the introduction of slow streamsv of water into'the sand layer" at spaced points along the b ottom ofthe conduit. The resulting sand layer is trapped'anddiverted downwardly, while the oil layer which has formed on top of thesand ows along a path beyond that of the sand 'and'is separately removed.

It isI notev'vorthythat theforegoing procedure, Vwhich avoids any frothing of the oil as well as the use of any oil diluent as in other processes, is particularly eiective in getting rid of the clay or silt, since this material is substantially all dispersed in and retained by the water layer. Re-use of the water, after the clay or silt has been settled from it in the settling pond avoids the loss of detergent and minimizes the amount of it used for continuous practice of the process.

The cooler 36, as illustrated in Fig. 1, is provided to insure that the water, which is used to disperse the mulled tar sand, will be cold enough so that thefseparating step will be conducted at a temperature below 50 F. as previously specified. However, in cold climates such as in the Athabasca district of Alberta, the use of such cooling means may not be necessary during most of the time, as the available water usually will have the desired low temperature. When necessary, cooling of the water, as schematically illustrated by cooler 36, may conveniently and economically be done by well known evaporation methods, although any other desired procedure may be employed.

The foregoing description is directed to illustrative embodiments of apparatus and procedure for practicing the invention, and it will be understood that various modifications may be made without departing from the scope of the invention. By way of example, while the inclined conduit has been illustrated as having a circular crosssection, it also may be ovate, rectangular, triangular, or the like.

What I claim is:

l. Method of separating oil from bituminous sands, such as Alberta tar sands, in which the oil has a density greater than that of water, which comprises: mulling the buminous sand with a minor amount of water at a temperature above 50 F. for a time sufficient to break the oil film from around the sand particles but insutiicient to cause the oil to stick to the sand; vigorously mixing the mulled material with a large volume of cold water;

feeding the resulting mixture at a temperature` above freezing butl belowf50q. E. into a separating zone having abttomwall inclined at anangle of 28-35 and subjected to vibrationsgilowing the mixture along the bottom walfwhile maintaining a water level in the upper part of thev Vseparating zone, whereby sand particles separate as a'lower layer, oil separates as an intermediate layer and watercontaining clay or silt separates as an upper layerj andl separately removing said layers.

' 2. Method of separating oil from bituminous sands, such as Alberta tar sands, in which the oil has a density greater than that of water, which comprises: mulling the bituminous sandwith ya minor amount of water at a temperature in the range of 50-100" F. for a time suf tieient to break the oil tilm from around the sand particles but insufiicient to cause the oil to stick to the sand; vigorously rmixing the mulled material with a large volume of cold water; feeding the resulting mixture at a ternperature above freezing but'below 50 F. into a separating zonevhaving a bottom wall inclined at an angle of 28g-35 and subjected to vibrations; ilowing the mixture along said bottom wall while maintaining a water level in the upper partei? thekseparating zone, whereby sand particles separate as a lower layer, oil separates as an intermediate layer and water containing clay or silt separates as an upperlayer; diverting the sand layer downwardly along a vpath more nearly vertical than said bottom and thereby separately removing it;l removing oil along a path beyond the path of the sand; and separately removing the Water layer containing clay or silt.

3.v Methodv o f separating oil from bituminous sands, such as rAlberta tarsands, in which the oil has a density greater than that of water, which comprises: mulling the bituminous sandwith 5-25% by volume of water containingna detergent at a temperature in the range of` 50,- F.. for a time suicient to break the oil lm from` around the sand particles but insuicient to cause the oil to stick to the sand; vigorously mixing the mulled material with at least l0 times its volume of cold water; feeding the resulting mixture at a temperature above freezing but below 50 F. into a separating zone having a bottom wall inclined at an angle of 28-35 and subjected to vibrations; flowing the mixture along said bottom wall while maintaining a liquid level in the upper part of the separating zone, whereby sand particles separate as a lower layer, oil separates as an intermediate layer and water containing clay or silt separates as an upper layer; and separately removing said layers.

4. Method of separating oil from bituminous sands, such as Alberta tar sands, in which the oil has a density greater than that of water, which comprises: mulling the bituminous sand with 525% by volume of water containing a detergent at a temperature in the range of Sil-100 F. for a time suicient to break the oil lm from around the sand particles but insuicient to cause the oil to stick to the sand; vigorously mixing the mulled material with at least l0 times its volume of cold water; feeding the resulting mixture at a temperature above freezing but below 50 F. into a separating zone having a bottom wall inclined at an angle of 28-35 and subjected to vibrations; owing the mixture along the bottom wall while maintaining a liquid level in the upper part of the separating zone, whereby sand particles separate as a lower layer, oil separates as an intermediate layer and water containing clay or silt separates as an upper layer; diverting the sand layer downwardly along a path more nearly vertical than said lower surface and thereby separately removing it; removing oil along a path beyond the path of the sand; and separately removing the water layer containing clay or silt.

5. Method according to claim 4 wherein slow streams of water are introduced upwardly at spaced points along said bottom wall to aid in preventing packing of the sand particles and in separating the oil from sand.

6. Method according to claim 2 wherein a slow stream 7 of water is introduced into the diverted sand adjacent its locus of removal to aid in preventing packing of the sand particles.

7. Method according to claim 6 wherein slow streams of water are introduced upwardly at spaced points along said bottom wall to aid in preventing packing of the sand particles and in separating the oil from sand.

8. Apparatus for separating oil from bituminous sands, such as Alberta tar sands, in which the oil has a density greater than that of water, which comprises: a conduit adapted to be lled with liquid and having a bottom wall inclined at an angle of 28-35; means for introducing a dispersion of mulled bituminous sand in Water into the conduit adjacent the upper end of said inclined bottom wall; means for regulating the temperature of said dispersion below 50 F. but above freezing; means for vibrating the conduit to aid in causing the introduced material to flow down said bottom wall and separate into a lower sand layer, an intermediate oil layer and an upper water layer; means for introducing slow streams of water upwardly at spaced points along and through said bottom wall to aid in preventing packing of the sand particles and in separating the oil from sand; and means for separately removing said layers.

9. Apparatus for separating oil from bituminous sands, such as Alberta tar sands, in which the oil has a density greater than that of water, which comprises: a conduit adapted to betilled with liquid and having a bottom wall inclined at an angle of 28-35 means for introducing a dispersion of mulled bituminous sand in water into the conduit adjacent the upper end of said inclined bottom wall; means for regulating the temperature of said dispersion below 50 F. but above freezing; means for vibrating the conduit to aid in causing the introduced material to ilow down said bottom wall and separate into a lower sand layer, an intermediate oil layer and an upper water layer; means for introducing slow streams of water upwardly at spaced points along and through said bottom wall to aid' in preventing packing of the sand particles and in separating the oil from sand; sand trapping means for separately diverting the sand layer into a downward path; means for drawing-off sand from the sand trapping means; means for separately drawingolf oil from the intermediate layer; and means for separately drawing olf the water layer.

10. Apparatus according to claim 9 including means for introducing a slow stream of water into the sand trapping means to aid in preventing packing of the sand particles.

11. Method according to claim 1 wherein slow streams of water are introduced upwardly at spaced points along said bottom wall to aid in preventing packing of the sand particles and in separating the oil from sand.

12. Method according to claim 4 wherein a slow stream of water is introduced into the diverted sand adjacent its locus of removal to aid in preventing packing of the sand particles.

13. Method according to claim l2 wherein slow streams of water are introduced upwardly at spaced points along said bottom wall to aid in preventing packing of the sand particles and in separating the oil from sand.

References Cited in the file of this patent UNITED STATES PATENTS 1,312,266 Navin Aug. 5, 1919 1,486,243 Hackstat Mar. l1, 1924 1,497,607 Streppel June 10, 1924 1,592,179 Clarke July 13, 1926 1,791,797 Clark Feb. 10, 1931 2,298,015 Lincoln Oct. 6, 1942 2,334,217 Rathjens Nov. 16, 1943 2,489,700 Coast Nov. 29, 1949 2,538,285 Swayze Ian. 16, 1951

Claims (1)

1. METHOD OF SEPARATING OIL FROM BITUMINOUS SANDS, SUCH AS ALBERTA TAR SANDS, IN WHICH THE OIL HAS A DENSITY GREATER THAN THAT OF WATER, WHICH COMPRISES: MULLING THE BITUMINOUS SAND WITH A MINOR AMOUNT OF WATER AT A TEMPERATURE ABOVE 50*F. FOR A TIME SUFFICIENT TO BREAK THE OIL FILM FROM AROUND THE SAND PARTICLES BUT INSUFFICIENT TO CAUSE THE OIL TO STICK TO THE SAND; VIGOROUSLY MIXING THE MULLED MATERIAL WITH A LARGE VOLUME OF COLD WATER; FEEDING THE RESULTING MIXTURE AT A TEMPERATURE ABOVE FREEZING BUT BELOW 50*F. INTO A SEPARATING ZONE HAVING A BOTTOM WALL INCLINED AT AN ANGLE OF 28-35* AND SUBJECTED TO VIBRATIONS; FLOWING THE MIXTURE ALONG THE BOTTOM WALL WHILE MAINTAINING A WATER LEVEL IN THE UPPER PART OF THE SEPARATING ZONE, WHEREBY SAND PARTICLES SEPARATE AS A LOWER LAYER, OIL SEPARATES AS AN INTERMEDIATE LAYER AND WATER CONTAINING CLAY OR SILT SEPARATES AS AN UPPER LAYER; AND SEPARATELY REMOVING SAID LAYERS.

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