CA1066643A - Treatment of tumbler reject - Google Patents
Treatment of tumbler rejectInfo
- Publication number
- CA1066643A CA1066643A CA269,028A CA269028A CA1066643A CA 1066643 A CA1066643 A CA 1066643A CA 269028 A CA269028 A CA 269028A CA 1066643 A CA1066643 A CA 1066643A
- Authority
- CA
- Canada
- Prior art keywords
- slurry
- bitumen
- tumbler
- water
- tar sand
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Abstract
"TREATMENT OF TUMBLER REJECT"
ABSTRACT OF THE DISCLOSURE
In the hot water process wherein tar sand is slurried in a tumbler with hot water and sodium hydroxide, oversized material, rejected from the tumbler, is mixed with a portion of slurry flood water in a second slurrying device and subjected therein to heating and dispersal of bitumen as-sociated with the rejects. A bitumen-containing slurry is produced from the second device and this slurry is combined with the tumbler slurry and subsequently subjected to flota-tion to recover bitumen.
ABSTRACT OF THE DISCLOSURE
In the hot water process wherein tar sand is slurried in a tumbler with hot water and sodium hydroxide, oversized material, rejected from the tumbler, is mixed with a portion of slurry flood water in a second slurrying device and subjected therein to heating and dispersal of bitumen as-sociated with the rejects. A bitumen-containing slurry is produced from the second device and this slurry is combined with the tumbler slurry and subsequently subjected to flota-tion to recover bitumen.
Description
` ~066643 BACKGROUND OF THE INVENTION
_ _ _ The invention finds application in the recovery of bitumen from bituminous sands in the process generally known as the hot water process. More particularly, the in-vention describes a process for obtaining bitumen from over-sized material rejected from the conditioning vessel in which bituminous sand is slurried with hot water in said process.
A large proportion of the world's known hydro-carbon reserves exists in the form of bituminous sand, com-monly referred to in the industry as tar sand and hence so referred to hereinafter. One large deposit of this material is found in Alberta, Canada, in an area traversed by the Athabasca River. The tar sand is believed to exist in the form of water-wet grains of sand sheathed in films of bitumen.
The bitumen is a valuable hydrocarbon material because, by suit-able methods of upgrading and refining, it can be converted to refined liquid and gaseous products useful for domestic and industrial purposes.
The sand particles in the deposit are generally of such a size as to be retained by a screen of 325 mesh, although clays and silts having much smaller particle size are also present. The quantity of bitumen as a proportion of the total composition is typically of the order of 12~ by weight.
Many methods have been proposed for recovering the hydrocarbons from tar sand. These include removing the hydrocarbons from mined tar sand by solvent extraction, or by separation with hot water, or by direct thermal treatment.
Still other methods, the so-called in situ methods, dispense with the mining step and render the hydrocarbons recoverable by treating the tar sand (usually with heat) in place. -~'.' , ~ '';:-
_ _ _ The invention finds application in the recovery of bitumen from bituminous sands in the process generally known as the hot water process. More particularly, the in-vention describes a process for obtaining bitumen from over-sized material rejected from the conditioning vessel in which bituminous sand is slurried with hot water in said process.
A large proportion of the world's known hydro-carbon reserves exists in the form of bituminous sand, com-monly referred to in the industry as tar sand and hence so referred to hereinafter. One large deposit of this material is found in Alberta, Canada, in an area traversed by the Athabasca River. The tar sand is believed to exist in the form of water-wet grains of sand sheathed in films of bitumen.
The bitumen is a valuable hydrocarbon material because, by suit-able methods of upgrading and refining, it can be converted to refined liquid and gaseous products useful for domestic and industrial purposes.
The sand particles in the deposit are generally of such a size as to be retained by a screen of 325 mesh, although clays and silts having much smaller particle size are also present. The quantity of bitumen as a proportion of the total composition is typically of the order of 12~ by weight.
Many methods have been proposed for recovering the hydrocarbons from tar sand. These include removing the hydrocarbons from mined tar sand by solvent extraction, or by separation with hot water, or by direct thermal treatment.
Still other methods, the so-called in situ methods, dispense with the mining step and render the hydrocarbons recoverable by treating the tar sand (usually with heat) in place. -~'.' , ~ '';:-
- 2 -. ~ ~ . . . . ..
-. :. - . . , . .. . , . .. ~ : , , - .,. , -.
10~6~;43 Tar sand presents considerable difficulties in ~-the recoYery of the bitumen partly because of the very fine nature of some of the mineral solids and partly because of the -intimate admixture of the mineral solids and the bitumen. At present the only commercially viable method is the hot water process. The aim of this process is to separate the bitumen fron~ tar sand and in such a form as to allow further purifi-cation to remove substantially all associated water and mineral solids. According to the hot water process, mined tar sand is fed to a rotating conditioning vessel, usually known as the "tumbler", where it is treated with hot water. The water is commonly heated by steam, added directly to the tumbler.
Sodium hydroxide is also added in such quantities as to raise the pH of the mixture to about 9Ø Feed materials are fed to -~
the tumbler in the following typical proportions by weight:
tar sand, 3250; water 610.3; sodium hydroxide solution ~at a specific gravity of 1.22) 4.06.
On emerging from the tumbler, the conditioned slurry is screened and diluted with hot flood water to the extent that the composition of the diluted slurry is typically 7.30% bitumen, 42.52% water and 50.18% mineral solids. This mixture is then subjected to bitumen separation. This involvPs treating it in a flotation vessel, so designed as to allow the bitumen to rise as a froth typically containing 66.4% bitu-men, 8.9% mineral solids, and 24.7% water. A further yield of bitumen is obtained from the middlings phase of the flotation vessel and, after combination, the combined froths are treated -with a diluent hydrocarbon and advanced to centrifuges to produce purified hydrocarbon mixture which, in turn, may be distilled to remove the diluent so that the resulting free bitumen may then be converted to hydrocarbons of lower rnolecular ;~
weight, collectively known as synthetic crude oil, by thermal .
`` 1066643 treatment.
The slurrying step performed in the tumbler dislodges the bitumen from the tar sand. The slurrying time and mixing intensity can be altered according to the type of tar sand feed being introduced to the tumbler. However the conditions to which the tar sand is subjected affect not only the degree of tar sand digestion, but also the ease with which the bitumen may be isolated from the mixtures in the sub-sequent separatory steps. Too vigorous treatment or too extended a residence time leads to over-conditioning, which interferes with and reduces the recovery of bitumen in the separatory steps. To avoid over-conditioning, the tumbler must be operated in such a way that some of the harder, more resistant lumps of tar sand are allowed to pass through the tumbler substantially unaffected by the hot water treatment and, on being rejected by the exit screens mentioned above, are removed from the process, thus representing loss of bitumen product. In addition the exit screens also reject oversized rocks and other debris and, as these are coated with a layer of bitumen-containing material, their rejection also contributes -to loss of bitumen from the process.
Typically the bitumen content of the rejects is 2.00% by weight and represents about 0.5% of the bitumen in the tar sand feed.
SUMMARY OF THE INVENTION
Hitherto the prior art has made no provision for recovering bitumen rejected from the circuit with the oversized rejects. The present invention is of benefit in the ;
hot water process partly because it allows for recovery of bitumen from tumbler rejects and partly because it achieves this without introducing more water to the process.
.~ . . . . .
- 10~;~6~3 According to the invention, oversized tumbler rejects removed by the exit screens, instead of being dis-carded from the process, are mixed with a portion of the flood water, heretofore added to the tumbler slurry, in a secondary ~ -slurrying device, to produce a bitumen-containing aqueous -stream. The product emerging from this secondary slurrying device is essentially a mixture of water, dispersed sand, and bitumen, together with rocks, and other debris, as well as ;~
any lumps of undigested tar sand that pass through this second treatment. To prevent such oversized material from entering the separatory vessels downstream, the output from the secondary slurrying device is passed through a vibrating screen similar to that used for removing rejects from the slurry emerging from the initial tumbler. The material pas-sing the screen is essentially water, dispersed sand, and bitumen, together with small-sized rocks, while the rejects from this second-stage screening consist principally of rocks and other debris substantially free of bitumen. Such washed rejects commonly have a bitumen content of 0.5% by weight or less, and are discarded. Hence, bitumen that would be lost in the tumbler rejects according to prior art technology is, by the use of the invention, retained in the process to be recovered in the bituminous froth collected in the subsequent separatory steps.
In a preferred embodiment, the tumbler slurry flood water is so divided that: one portion enters the secondary slurrying device; another portion acts as wash water to bathe the secondary screen; a third portion is added to the slurry product passing through the secondary screen;
and the remainder is added in the usual location i.e. the slurry sump situated beneath the primary screen. In this , ~ , , .: . .
10666~3 emhodiment, the cecondary diluted screened s.lurry is combined wi.th the pri~ary diluted screened slurry.and advanced to the separatory step.
The division of fresh process water among the vari.ous locations in the two conditioning circui:ts may be varied according to the ease of digestion of the tar sand feed, the proportion of oversized material in the tar sand feed, and the type of slurrying device used in the secondary conditioning circuit. Nor is it necessary that fresh process water should be added at all points. Aqueous streams. taken from other parts of the extraction process may be used alone or combined with fresh process water for these locations. For instance, mixing a portion of middlings from the downstream separatory step with fres.h water for use in the secondary slurrying device can lead, in the case of certain tar sand feeds, to reduced total water usage and improved.bitumen recovery for the process overall. Similarly, the diluted screened slurry from the secondary conditioning circuit may be added to the primary conditioning circuit e{ther alone or with fresh process water by being introduced to any or all of the water addition locations: the tumbler, the screen wash, or the slurry dilution locat10n.
Broadly stated, the i:nventi.on i.s an improvement i.n the process for produci.ng a flooded slurry of tar sand containing bitumen which .
comprises: mixing tar sand with hot water in a rotating conditioning vessel to produce a fi.rst slurry containing rocks and lumps of tar sand; ;
screening the fi.rst slurry to remove a reject porti:on mainly comprising said rocks and lumps, both associated with bitumen; mixing said reject portion with.hot water in another rotating condi`tioning vessel to disperse ~
~' ':
. . .. ~ . . . .. .. .
10~;6643 :
associated bitumen and produce a second slurry containing rocks and some remaining lumps of tar s.and; and s.creeni.ng rocks and lumps from sai.d second slurry and combining the screened second slurry with the screened ~.
first slurry to form a flooded slurry capable of being pumped tq a ~-separation vessel.
In the drawings:
Figure 1 is a block.diagram setting forth. the steps i:nvolved in a preferred form of the invention; and Fi:gure 2 is a schematic drawing illustrating the preferred embodiment of the i.nventi.on of Figure 1.
DESCRIPTION OF TWE PREFERRED EMBODIMENT
The invention is i.llustrated by the following example usi.ng a circuit as sh.own i.n the Figures.
Tar sand having an average composi:ti.on of 11.59% by we.ight b.itumen, 84.00% solids and 4.41% water i:s fe.d to a rotating tumhler 1, at a rate of 3250 pounds/hour. Hot slurry water, at a temperature of 190F is added to the tumbler 1 at a rate of 61a.3 pounds/hour.
Steam, at a pressure of 50 psi.g i:s. also fed to the tumhler 1 at a rate.
of 148.2 pounds/hour. The tumbler 1 produces a first slurry comprisi:ng ;~
9.40% bi.tumen, 22.50% water and 68 1Q% solids which is washed through a 1/4 i.nch mesh screen 2 wi.th 235.4 pounds/hour of screen wash. The oversi.ze rock and lump rejects from screen 2 amount to 188.3 pounds/hour and contain 2% bi:tumen by weight.
These rejects are fed to a tumbler or secondary slurrying devi.ce 3 and mixed with 25.Q pounds/hDur of water at l9QF. Thi:s water constitutes a port;.on of the total flood water. Tumhler 3 produces a second slurry containing 1.76%
bitumen, 2Q.54% water, and 77.70% soli.ds whîch i:s washed th.rough a 1~4 inch mesh screen 4 wi.th.ZO.O poundsthour of ~ . . .
-- .
, . . - - ~
- ~, screen wash. Oversize reject from the screen 4 amounts to 20.0 pounds/hour and contains 0.5~bitumen by weight. Second slurry underflow from the screen 4 is collected in the flooding stream sump 5 and an additional portion of the total flood water, 100 pounds~hour, is added into this sump to produce a flooded second slurry containing 1.16% bitumen, 51.96~
water, and 46.86% solids. This stream plus the remaining flood water, 935.3 pounds/hour, is fed to the slurry sump 6 which receives the first slurry underflow from the screen 2.
The combination of these streams yields a flooded slurry containing 7.10% bitumen, 41.80% water and 51.10% solids and this slurry is then subjected to bitumen separation and recovery.
.,.. " , . . .
.
' .
-. :. - . . , . .. . , . .. ~ : , , - .,. , -.
10~6~;43 Tar sand presents considerable difficulties in ~-the recoYery of the bitumen partly because of the very fine nature of some of the mineral solids and partly because of the -intimate admixture of the mineral solids and the bitumen. At present the only commercially viable method is the hot water process. The aim of this process is to separate the bitumen fron~ tar sand and in such a form as to allow further purifi-cation to remove substantially all associated water and mineral solids. According to the hot water process, mined tar sand is fed to a rotating conditioning vessel, usually known as the "tumbler", where it is treated with hot water. The water is commonly heated by steam, added directly to the tumbler.
Sodium hydroxide is also added in such quantities as to raise the pH of the mixture to about 9Ø Feed materials are fed to -~
the tumbler in the following typical proportions by weight:
tar sand, 3250; water 610.3; sodium hydroxide solution ~at a specific gravity of 1.22) 4.06.
On emerging from the tumbler, the conditioned slurry is screened and diluted with hot flood water to the extent that the composition of the diluted slurry is typically 7.30% bitumen, 42.52% water and 50.18% mineral solids. This mixture is then subjected to bitumen separation. This involvPs treating it in a flotation vessel, so designed as to allow the bitumen to rise as a froth typically containing 66.4% bitu-men, 8.9% mineral solids, and 24.7% water. A further yield of bitumen is obtained from the middlings phase of the flotation vessel and, after combination, the combined froths are treated -with a diluent hydrocarbon and advanced to centrifuges to produce purified hydrocarbon mixture which, in turn, may be distilled to remove the diluent so that the resulting free bitumen may then be converted to hydrocarbons of lower rnolecular ;~
weight, collectively known as synthetic crude oil, by thermal .
`` 1066643 treatment.
The slurrying step performed in the tumbler dislodges the bitumen from the tar sand. The slurrying time and mixing intensity can be altered according to the type of tar sand feed being introduced to the tumbler. However the conditions to which the tar sand is subjected affect not only the degree of tar sand digestion, but also the ease with which the bitumen may be isolated from the mixtures in the sub-sequent separatory steps. Too vigorous treatment or too extended a residence time leads to over-conditioning, which interferes with and reduces the recovery of bitumen in the separatory steps. To avoid over-conditioning, the tumbler must be operated in such a way that some of the harder, more resistant lumps of tar sand are allowed to pass through the tumbler substantially unaffected by the hot water treatment and, on being rejected by the exit screens mentioned above, are removed from the process, thus representing loss of bitumen product. In addition the exit screens also reject oversized rocks and other debris and, as these are coated with a layer of bitumen-containing material, their rejection also contributes -to loss of bitumen from the process.
Typically the bitumen content of the rejects is 2.00% by weight and represents about 0.5% of the bitumen in the tar sand feed.
SUMMARY OF THE INVENTION
Hitherto the prior art has made no provision for recovering bitumen rejected from the circuit with the oversized rejects. The present invention is of benefit in the ;
hot water process partly because it allows for recovery of bitumen from tumbler rejects and partly because it achieves this without introducing more water to the process.
.~ . . . . .
- 10~;~6~3 According to the invention, oversized tumbler rejects removed by the exit screens, instead of being dis-carded from the process, are mixed with a portion of the flood water, heretofore added to the tumbler slurry, in a secondary ~ -slurrying device, to produce a bitumen-containing aqueous -stream. The product emerging from this secondary slurrying device is essentially a mixture of water, dispersed sand, and bitumen, together with rocks, and other debris, as well as ;~
any lumps of undigested tar sand that pass through this second treatment. To prevent such oversized material from entering the separatory vessels downstream, the output from the secondary slurrying device is passed through a vibrating screen similar to that used for removing rejects from the slurry emerging from the initial tumbler. The material pas-sing the screen is essentially water, dispersed sand, and bitumen, together with small-sized rocks, while the rejects from this second-stage screening consist principally of rocks and other debris substantially free of bitumen. Such washed rejects commonly have a bitumen content of 0.5% by weight or less, and are discarded. Hence, bitumen that would be lost in the tumbler rejects according to prior art technology is, by the use of the invention, retained in the process to be recovered in the bituminous froth collected in the subsequent separatory steps.
In a preferred embodiment, the tumbler slurry flood water is so divided that: one portion enters the secondary slurrying device; another portion acts as wash water to bathe the secondary screen; a third portion is added to the slurry product passing through the secondary screen;
and the remainder is added in the usual location i.e. the slurry sump situated beneath the primary screen. In this , ~ , , .: . .
10666~3 emhodiment, the cecondary diluted screened s.lurry is combined wi.th the pri~ary diluted screened slurry.and advanced to the separatory step.
The division of fresh process water among the vari.ous locations in the two conditioning circui:ts may be varied according to the ease of digestion of the tar sand feed, the proportion of oversized material in the tar sand feed, and the type of slurrying device used in the secondary conditioning circuit. Nor is it necessary that fresh process water should be added at all points. Aqueous streams. taken from other parts of the extraction process may be used alone or combined with fresh process water for these locations. For instance, mixing a portion of middlings from the downstream separatory step with fres.h water for use in the secondary slurrying device can lead, in the case of certain tar sand feeds, to reduced total water usage and improved.bitumen recovery for the process overall. Similarly, the diluted screened slurry from the secondary conditioning circuit may be added to the primary conditioning circuit e{ther alone or with fresh process water by being introduced to any or all of the water addition locations: the tumbler, the screen wash, or the slurry dilution locat10n.
Broadly stated, the i:nventi.on i.s an improvement i.n the process for produci.ng a flooded slurry of tar sand containing bitumen which .
comprises: mixing tar sand with hot water in a rotating conditioning vessel to produce a fi.rst slurry containing rocks and lumps of tar sand; ;
screening the fi.rst slurry to remove a reject porti:on mainly comprising said rocks and lumps, both associated with bitumen; mixing said reject portion with.hot water in another rotating condi`tioning vessel to disperse ~
~' ':
. . .. ~ . . . .. .. .
10~;6643 :
associated bitumen and produce a second slurry containing rocks and some remaining lumps of tar s.and; and s.creeni.ng rocks and lumps from sai.d second slurry and combining the screened second slurry with the screened ~.
first slurry to form a flooded slurry capable of being pumped tq a ~-separation vessel.
In the drawings:
Figure 1 is a block.diagram setting forth. the steps i:nvolved in a preferred form of the invention; and Fi:gure 2 is a schematic drawing illustrating the preferred embodiment of the i.nventi.on of Figure 1.
DESCRIPTION OF TWE PREFERRED EMBODIMENT
The invention is i.llustrated by the following example usi.ng a circuit as sh.own i.n the Figures.
Tar sand having an average composi:ti.on of 11.59% by we.ight b.itumen, 84.00% solids and 4.41% water i:s fe.d to a rotating tumhler 1, at a rate of 3250 pounds/hour. Hot slurry water, at a temperature of 190F is added to the tumbler 1 at a rate of 61a.3 pounds/hour.
Steam, at a pressure of 50 psi.g i:s. also fed to the tumhler 1 at a rate.
of 148.2 pounds/hour. The tumbler 1 produces a first slurry comprisi:ng ;~
9.40% bi.tumen, 22.50% water and 68 1Q% solids which is washed through a 1/4 i.nch mesh screen 2 wi.th 235.4 pounds/hour of screen wash. The oversi.ze rock and lump rejects from screen 2 amount to 188.3 pounds/hour and contain 2% bi:tumen by weight.
These rejects are fed to a tumbler or secondary slurrying devi.ce 3 and mixed with 25.Q pounds/hDur of water at l9QF. Thi:s water constitutes a port;.on of the total flood water. Tumhler 3 produces a second slurry containing 1.76%
bitumen, 2Q.54% water, and 77.70% soli.ds whîch i:s washed th.rough a 1~4 inch mesh screen 4 wi.th.ZO.O poundsthour of ~ . . .
-- .
, . . - - ~
- ~, screen wash. Oversize reject from the screen 4 amounts to 20.0 pounds/hour and contains 0.5~bitumen by weight. Second slurry underflow from the screen 4 is collected in the flooding stream sump 5 and an additional portion of the total flood water, 100 pounds~hour, is added into this sump to produce a flooded second slurry containing 1.16% bitumen, 51.96~
water, and 46.86% solids. This stream plus the remaining flood water, 935.3 pounds/hour, is fed to the slurry sump 6 which receives the first slurry underflow from the screen 2.
The combination of these streams yields a flooded slurry containing 7.10% bitumen, 41.80% water and 51.10% solids and this slurry is then subjected to bitumen separation and recovery.
.,.. " , . . .
.
' .
Claims
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for producing a flooded slurry of tar sand containing bitumen which comprises:
mixing tar sand with not water in a rotating conditioning vessel to produce a first slurry containing rocks and lumps of tar sand;
screening the first slurry to remove a reject portion mainly comprising said rocks and lumps, both associated with bitumen;
mixing said reject portion with hot water in another rotating conditioning vessel to disperse associated bitumen and produce a second slurry containing rocks and some remaining lumps of tar sand; and screening rocks and lumps from said second slurry and combining the screened second slurry with the screened first slurry to form a flooded slurry capable of being pumped to a separation vessel.
mixing tar sand with not water in a rotating conditioning vessel to produce a first slurry containing rocks and lumps of tar sand;
screening the first slurry to remove a reject portion mainly comprising said rocks and lumps, both associated with bitumen;
mixing said reject portion with hot water in another rotating conditioning vessel to disperse associated bitumen and produce a second slurry containing rocks and some remaining lumps of tar sand; and screening rocks and lumps from said second slurry and combining the screened second slurry with the screened first slurry to form a flooded slurry capable of being pumped to a separation vessel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA269,028A CA1066643A (en) | 1976-12-31 | 1976-12-31 | Treatment of tumbler reject |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA269,028A CA1066643A (en) | 1976-12-31 | 1976-12-31 | Treatment of tumbler reject |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1066643A true CA1066643A (en) | 1979-11-20 |
Family
ID=4107639
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA269,028A Expired CA1066643A (en) | 1976-12-31 | 1976-12-31 | Treatment of tumbler reject |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1066643A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5264118A (en) * | 1989-11-24 | 1993-11-23 | Alberta Energy Company, Ltd. | Pipeline conditioning process for mined oil-sand |
-
1976
- 1976-12-31 CA CA269,028A patent/CA1066643A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5264118A (en) * | 1989-11-24 | 1993-11-23 | Alberta Energy Company, Ltd. | Pipeline conditioning process for mined oil-sand |
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