Abstract
A method for processing a froth treatment tailings separated from a bitumen froth produced in a process for recovering bitumen from oil sand ore, includes subjecting the froth treatment tailings to a first solvent extraction process to produce a first extract including bitumen, and a first raffinate, subjecting the first raffinate to a separation process to produce a fine mineral material fraction including fine solid mineral material having a particle size less than 44 microns and a coarse mineral material fraction including a coarse mineral material having a particle size equal to or greater than 44 microns, subjecting the coarse mineral material fraction to a froth flotation process to produce a heavy mineral concentrate and a coarse mineral material tailings, and subjecting the heavy mineral concentrate to a second solvent extraction process to produce a second extract including bitumen and a second raffinate including a debitumenized heavy mineral concentrate.
Claims
1. A method for processing a froth treatment tailings separated from a bitumen froth produced in a process for recovering bitumen from oil sand ore, wherein the froth treatment tailings comprises a solid mineral material a bitumen, and water, wherein the solid mineral material comprises a coarse solid mineral material having a particle size equal to or greater than about 44 microns and a fine solid mineral material having a particle size less than about 44 microns, the method comprising: (a) subjecting the froth treatment tailings to a first solvent extraction process to produce a first extract and a first raffinate; wherein the first extract comprises a first extract amount of the bitumen; and wherein the first raffinate comprises the solid mineral material, a first raffinate amount of the bitumen, and water; (b) subjecting the first raffinate to a separation process to produce a fine mineral material fraction and a coarse mineral fraction therefrom; wherein the fine mineral material fraction comprises the fine solid mineral material; and wherein the coarse mineral material fraction comprises the coarse solid mineral material, a coarse fraction amount of the bitumen, and wafer; (c) subjecting the coarse mineral material fraction to a froth flotation process to produce a heavy mineral concentrate and a coarse mineral material tailings therefrom; wherein the heavy mineral concentrate comprises a heavy mineral concentrate amount of the coarse solid mineral material, a heavy mineral concentrate amount of the bitumen, and water; and (d) subjecting the heavy mineral concentrate to a second solvent extraction process to produce a second extract and a second raffinate; wherein the second extract comprises a second extract amount of the bitumen; and wherein the second raffinate comprises a debitumenized heavy mineral concentrate.
2. The method of claim 1 wherein the process for recovering bitumen from oil sands comprises a paraffinic froth treatment process for producing the bitumen froth.
3. The method of claim 1 wherein the first solvent extraction process comprises adding a hydrocarbon diluent to the froth treatment tailings.
4. The method of claim 3 wherein the hydrocarbon diluent is added to the froth treatment tailings in a ratio by weight within the range of about 0.3 to about 0.5.
5. The method of claim 3 wherein the bitumen in the froth treatment tailings comprises a combination of an asphaltene enriched bitumen component and a maltene component, and the method further comprises selecting a relative proportion of a naphthenic type diluent to a paraffinic type diluent in the hydrocarbon diluent to selectively vary the relative proportion of the asphaltene enriched bitumen component to the maltene component in the first extract amount of the bitumen.
6. The method of claim 1 wherein the method further comprises subjecting an intermediate product to a diluent recovery process to produce a recovered diluent and a diluent recouped intermediate product, wherein the intermediate product comprises either one or a combination of the fine mineral material fraction and the coarse mineral material tailings, or the debitumenized heavy mineral concentrate.
7. The method of claim 6 wherein the intermediate product comprises one or a combination of the fine mineral material fraction or the coarse mineral material tailings, and the method further comprises dewatering the diluent recovered intermediate product.
8. The method of claim 7 wherein dewatering the diluent recovered intermediate product comprises: (a) adding a flocculant to the diluent recovered intermediate product to flocculate solids in the diluent recovered intermediate product to produce a mixture of diluent recovered intermediate product and flocculated solids; and (b) subjecting the mixture of diluent recovered intermediate product and flocculated solids to a gravity settling or enhanced gravity separation process to produce a recovered water portion and a thickened slurry therefrom.
9. The method of claim 8 wherein the flocculant comprises a polymer.
10. The method of claim 8 wherein the flocculant is added to the diluent recovered intermediate product in an amount of between about 200 ppmw to about 400 ppmw.
11. The method of claim 10 wherein the thickened slurry has a solids concentration of at least about 40 percent by weight.
12. The method of claim 8 wherein the recovered water portion is recycled to the process for recovering bitumen from oil sands.
Description
BRIEF DESCRIPTION OF DRAWINGS
[0155] Embodiments of the invention will now be described with reference to the accompanying drawings, in which:
[0156] FIG. 1 is schematic process flow diagram depicting an embodiment of the system of the invention used to implement an embodiment of the method of the invention, including depictions of alternate and/or optional features of the embodiment of the invention in dashed lines.
[0157] FIGS. 2A-2G are collectively a material balance for a laboratory bench scale experiment with respect to an embodiment of the method of the invention similar to that depicted in FIG. 1, conducted on a froth treatment tailings, using naphtha as a hydrocarbon diluent, wherein the froth treatment tailings are comprised of an amount of naphtha as a froth treatment diluent.
DETAILED DESCRIPTION
[0158] Referring to FIG. 1, a non-limiting exemplary embodiment of the method of the present invention is depicted schematically in a process flow diagram. The method is for processing froth treatment tailings in order to recover bitumen, diluent, and water therefom, and to produce a diluent recovered debitumenized heavy mineral concentrate therefrom.
[0159] A process for recovering bitumen from oil sand is comprised of producing a bitumen froth from the oil sand (not shown), and is further comprised of processing the bitumen froth in a froth treatment process (not shown) in order to separate froth treatment tailings (20) from the bitumen froth. The resulting froth treatment tailings (20) comprise solid mineral material, water and bitumen. In this exemplary embodiment, the froth treatment tailings (20) also comprise an amount of a naphthenic type froth treatment diluent which is used in the froth treatment process. The solid mineral material includes coarse mineral material and fine mineral material. A large proportion of the heavy minerals in the froth treatment tailings (20) are typically present as coarse mineral material in the froth treatment tailings (20). The tine mineral material which is included in the froth treatment tailings (20) does not typically contain significant amounts of heavy minerals.
First Solvent Extraction Process (40)
[0160] In the exemplary embodiment shown in FIG. 1, the froth treatment tailings (20) is subjected to a first solvent extraction process (40) in order to produce a first extract (42) and a fast raffinate (44). The first solvent extraction process (40) is performed using two stages of solvent extraction apparatus that are arranged in a countercurrent configuration. The first solvent extraction stage apparatus (50) of the first solvent extraction process (40) comprises a first mixer (52) and a first gravity settler (54). The second solvent extraction stage apparatus (56) of the first solvent extraction process (40) comprises a second mixer (58) and a second gravity settler (60). As depicted in FIG. 1, each of the gravity settlers (54, 60) comprises a gravity settling vessel.
[0161] The froth treatment tailings (20) are delivered to the first mixer (52) for mixing and are then delivered to the first gravity settler (54) in order to produce a first solvent extraction stage overflow product (62), and a first solvent extraction stage underflow product (64).
[0162] The first solvent extraction stage extraction overflow product (62) is the first extract (42). The first extract (42) is comprised of solid mineral material, water, and a first extract amount of the bitumen. The first extract (42) is also comprised of an amount of the froth treatment diluent from the froth treatment tailings (20) and an amount of the hydrocarbon diluent (70) that is present in the first extract (42) as a result of the recycling of the second solvent extraction stage overflow product (66) to the first mixer (52), as described below. The first extract (42) has a solid mineral material concentration by weight and a water concentration by weight (collectively referred to as the “BS&W content”). If the solid mineral material concentration, the water concentration and the BS&W content in the first extract (42) are below acceptable limits, the first extract (42) may be suitable for further processing and/or transport as a diluted bitumen (i.e., dilbit) product. The further processing of the first extract (42) may be comprised of subjecting the first extract (42) to a solvent recovery process for recovering substantially all or a portion of the froth treatment diluent and the hydrocarbon diluent (70) therefrom. If, however, the solid mineral material concentration and/or the water concentration by weight in the first extract (42) are above acceptable limits, the first extract (42) may be subjected to clarifying (not shown) in order to produce a clarified extract (not shown) which has a reduced solid mineral material concentration by weight and/or water concentration by weight in comparison with the first extract (42).
[0163] Referring to the exemplary embodiment shown in FIG. 1, a recycled amount of a first solvent extraction stage intermediate component (63) may optionally be combined with the froth treatment tailings (20) so that the first solvent extraction stage feed material in the first mixer (52) is further comprised of the recycled amount of the first solvent extraction stage intermediate component (63). The first solvent extraction stage intermediate component (63) is withdrawn from the first gravity settler (54) at a withdrawal point that is located below the level in the first gravity settler (54) where the first solvent extraction stage overflow component (62) accumulates, and that is located above the level in the first gravity settler (54) where the first solvent extraction stage underflow component (64) accumulates. The ratio by weight of the recycled amount of the first solvent extraction stage intermediate component (63) to the total amount of the first solvent extraction stage feed material in the first mixer (52) may be in the range of between about 0.1 to about 0.9, and more particularly in the range of between about 0.25 to 0.5.
[0164] The first solvent extraction stage underflow product (64) is delivered to the second mixer (58) for mixing and is then delivered to the second gravity settler (60) in order to produce a second solvent extraction stage overflow product (66), and a second solvent extraction stage underflow product (68). The second solvent extraction stage overflow product (66) is recycled to the first mixer (52).
[0165] An amount of a hydrocarbon diluent (70) is also delivered to the second mixer (58) for mixing with the first solvent extraction stage underflow product (64). In embodiments, the weight ratio of the amount of hydrocarbon diluent (70) that is delivered to the second mixer (58) to the amount of froth treatment tailings (20) may be in range of about 0.3 to 0.5.
[0166] The hydrocarbon diluent (70) is selected having regard to the composition of the froth treatment diluent. In the embodiment of FIG. 1, the hydrocarbon diluent (70) and the froth treatment diluent are comprised of a single naphthenic type diluent. In other embodiments, the hydrocarbon diluent (70) may be selected from a naphthenic type diluent (e.g., naphtha, or Jet B aviation fuel specification comprising an aromatic content of up to 20 percent by volume) and a paraffinic type diluent (e.g., varnish maker's and painters naphtha (VM & P) naphtha comprising an aromatic content of less than 1 percent by volume, pentane, or hexane). (As is known in the art, besides aromatic compounds, naphthenic type diluents and paraffinic type diluent may also comprise paraffins, olefins and naphthalenes.) In embodiments where the bitumen in the froth treatment tailings comprises a combination of an asphaltene enriched bitumen (AEB) component and a non-asphaltenic component (e.g., maltene), the type of hydrocarbon diluent (70) may be selected to selectively recover either the AEB component or the maltene component, or a desired proportion of both the AEB component and the maltene component. The naphthenic type diluent may be selected when it is desired to recover both the AEB component and the maltene component. The paraffinic type diluent may be selected when it is desired to recover the maltene component in preference to the AEB component.
[0167] Referring to the exemplary embodiment shown in FIG. 1, a recycled amount of a second solvent extraction stage intermediate component (67) may optionally be combined with the first solvent extract stage underflow product (64) and the hydrocarbon diluent (70) so that the second solvent extraction stage feed material in the second mixer (58) is further comprised of the recycled amount of the second solvent extraction stage intermediate component (67). The second solvent extraction stage intermediate component (67) is withdrawn from the second gravity settler (60) at a withdrawal point which is located below the level in the second gravity settler (60) where the second solvent extraction stage overflow component (66) accumulates and which is located above the level in the second gravity settler (60) where the second solvent extraction stage underflow component (68) accumulates. The ratio by weight of the recycled amount of the second solvent extraction stage intermediate component (67) to the total amount of the second solvent extraction stage feed material in the second mixer (58) may be in the range of between about 0.1 to about 0.9, and more particularly in the range of between about 0.25 to about 0.5.
[0168] In some embodiments, the second solvent extraction stage underflow product (68) may be withdrawn from the second gravity settler (60) at a rate that is less than the rate at which the first solvent extraction stage underflow product (64) is withdrawn from the first gravity settler (54). In embodiments, the ratio of the withdrawal rate of the second solvent extraction stage underflow product (68) to the withdrawal rate of the first solvent extraction stage underflow product (64) is in the range of between about 0 to about 1, and more particularly in the range between about 0.05 to about 0.5.
[0169] The second solvent extraction stage underflow product (68) is the first raffinate (44) and is subjected to further processing in the separation process (80), as described below.
Separation Process (80)
[0170] In the exemplary embodiment shown in FIG. 1, the method comprises subjecting the first raffinate (44) to a separation process (80) in order to produce a coarse mineral material fraction (82) that comprises the coarse solid mineral material and a fine mineral material fraction (84) that comprises the fine solid mineral material. In the exemplary embodiment depicted in FIG. 1, the separation process (80) comprises subjecting the first raffinate (44) to enhanced gravity separation by passing the first raffinate (44) through an enhanced gravity separation apparatus (86) such as a hydrocyclone.
[0171] The fine mineral material fraction (82) may be further processed in order to recover diluent therefrom in the first diluent recovery process (180), as described below. The coarse mineral material fraction (84) is subjected to further processing in the froth flotation process (100), as described below.
Froth Flotation Process (100)
[0172] The coarse mineral material fraction (84) is subjected to froth flotation process (100) in order to produce a heavy mineral concentrate (102) and a coarse mineral material tailings (104) therefrom. A purpose of the froth flotation process (100) is to concentrate the heavy minerals by rejecting the coarse mineral material tailings (104) in order to produce the heavy mineral concentrate (102). The heavy mineral concentrate (102) has a substantially smaller volume than the coarse mineral material fraction (44) and can therefore be processed more efficiently than the coarse mineral material fraction (44).
[0173] In the exemplary embodiment depicted in FIG. 1, the froth flotation process (100) is comprised of a first froth flotation stage (106) and a second froth flotation stage (108). As depicted in FIG. 1 the first froth flotation stage (106) is performed in a first flotation vessel (110) and the second froth flotation stage (108) is performed in a second flotation vessel (112).
[0174] In the exemplary embodiment depicted in FIG. 1, both the first froth flotation stage (106) and the second froth flotation stage (108) are performed in the presence of a suitable amount of an injected gas such as air (not shown) and in the presence of a suitable amount of a suitable frothing agent (not shown). Non-limiting examples of potentially suitable frothing agents include glycol based frothers and/or alcohol based bothers. As a specific non-limiting example, a suitable frothing agent may be Cytec™ F-507 frother, a product of Cytec Industries Inc., and may be added to the feed material to provide a frothing agent concentration of between about 15 grams and about 50 grams per tonne of feed material in each of the froth flotation stages (106, 108).
[0175] The froth flotation stages (106, 108) may be arranged in a scavenging configuration or in a cleaning configuration. The scavenging configuration of the froth flotation process (100) is depicted by solid lines in FIG. 1. The cleaning configuration of the froth flotation process (100) is depicted by dashed lines in FIG. 1.
[0176] In the scavenging configuration of the froth flotation process (100) the first froth flotation stage (106) is a rougher froth flotation stage and the second froth flotation stage (108) is a scavenger froth flotation stage so that subjecting the coarse mineral material fraction (82) to both flotation process (100) is comprised of subjecting the coarse mineral material fraction (82) to the rougher froth flotation stage in order to produce a rougher stage float product (114) and a rougher stage sink product (116), and is further comprised of subjecting the rougher stage sink product (116) to the scavenger froth flotation stage in order to produce a scavenger stage float product (118) and a scavenger stage sink product (119).
[0177] In the scavenging configuration of the froth flotation process (100) as depicted in FIG. 1, the rougher stage float product (114) and the scavenger stage float product (118) are combined so that the heavy mineral concentrate (102) is comprised of or consists essentially of the rougher stage float product (114) and the scavenger stage float product (118), while the coarse mineral material tailings (104) are comprised of or consist essentially of the scavenger stage sink product (119).
[0178] In the scavenging configuration of the froth flotation process (100), subjecting the rougher stage sink product (116) to the scavenger froth notation stage may be comprised of adding an amount of a collector (not shown) to the rougher stage sink product (116) in order to enhance the recovery of heavy minerals in the scavenger stage float product (118). As a specific non-limiting example, the collector may be comprised of a hydrocarbon liquid such as kerosene, naphtha or a mixture thereof. It is believed that, the collector adheres to heavy minerals which have amounts of bitumen attached thereto, thereby increasing the hydrophobicity and floatabillty of the heavy minerals.
[0179] In the scavenging configuration of the froth flotation process (100), the rougher froth flotation stage and the scavenger froth flotation stage are performed so that the residence time of the coarse mineral material fraction (82) in the rougher froth flotation stage (106) is longer than the residence time of the rougher stage sink product (116) in the scavenger froth flotation stage (108). For example, in some applications of the method of the invention, the residence time of the coarse mineral material fraction (82) in the rougher froth flotation (106) stage may be about 10 minutes, while the residence time of the rougher stage sink product (116) in the scavenger froth flotation stage (108) may be about 5 minutes.
[0180] In the cleaning configuration of the froth flotation process (100), the first froth flotation stage (106) is a rougher froth flotation stage and the second froth flotation stage (108) is a cleaner froth flotation stage so that subjecting the coarse mineral material fraction (82) to froth flotation process (100) is comprised of subjecting the coarse mineral material fraction (82) to the rougher froth flotation stage in order to produce a rougher stage float product (114a) and a rougher stage sink product (116a), and is further comprised of subjecting the rougher stage float product (114a) to the cleaner froth flotation stage in order to produce a cleaner stage float product (118a) and a cleaner stage sink product (119a).
[0181] In the cleaning configuration of the froth flotation process (100) as depicted in FIG. 1, the heavy mineral concentrate (102) is comprised of or consists essentially of the cleaner stage float product (118a). Furthermore, in the cleaning configuration of the froth flotation process (100) as depicted in FIG. 1, the rougher stage sink product (116a) and the cleaner stage sink product (119a) are combined so that she coarse mineral material tailings (104) are comprised of or consist essentially of the rougher stage sink product (116a) and the cleaner stage sink product (119a).
[0182] In the embodiments of both the scavenging configuration and the cleaning configuration of the froth flotation process (100) as described above, the coarse mineral material fraction (44) may have a solid mineral material concentration of between about 20 percent and about 30 percent by weight of the coarse mineral material fraction (44) when the coarse mineral material fraction (44) is introduced to the froth notation process (100) or more particularly, when the coarse mineral material fraction (44) is introduced to the first froth flotation stage (106).
Second Solvent Extraction Process (120)
[0183] The heavy mineral concentrate (102) is subjected to a second solvent extraction process (120) in order to produce a debitumenized heavy mineral concentrate (122) and a second extract (124) therefrom.
[0184] In the embodiment depicted in FIG. 1, the second solvent extraction process (120) is comprised of a first solvent extraction stage (126), a second solvent extraction stage (128) and a third solvent extraction stage (110).
[0185] In the exemplary embodiment shown in FIG. 1, the solvent extraction stages (126, 128, 130) are arranged in a countercurrent configuration. As a result, the second extract (124) is produced from the first solvent extraction stage (126) and the debitumenized heavy mineral concentrate (122) is produced from the third solvent extraction stage (130).
[0186] The first solvent extraction stage (126) is comprised of attritioning a first solvent extraction stage feed material (132) in order to produce an attritioned first solvent extraction stage feed material (134). The first solvent extraction stage (126) is further comprised of separating the attritioned first solvent extraction stage feed material (134) in order to produce a first solvent extraction stage underflow component (136) and a first solvent extraction stage overflow component (138).
[0187] The first solvent extraction stage feed material (132) is comprised of the heavy mineral concentrate (102) and includes a first solvent extraction stage amount (not shown) of a diluent. In a specific application of the embodiment of FIG. 1, the diluent consists essentially of naphtha and the first sol vent extraction stage amount of the diluent is at least about 15 percent by weight of the first solvent extraction stage feed material (132).
[0188] In the exemplary embodiment shown in FIG. 1, the diluent may be comprised of a hydrocarbon diluent which is added in the practice of the invention and/or the diluent may be comprised of a froth treatment diluent which was present in the froth treatment tailings (20) as a result of a froth treatment process.
[0189] In the exemplary embodiment shown in FIG. 1, the first solvent extraction stage feed material (132) may have a solid mineral material concentration of between about 10 percent and about 70 percent by weight of the first solvent extraction stage feed material (132). The first solvent extraction stage feed material (132) may be comprised of art amount of make-up water (not shown) to provide a desired solid mineral material concentration for the first solvent extraction stage feed material (132). The make-up water (not shown) may be comprised of or may consist essentially of fresh water and/or water which is recycled from the method of the invention or from other processes.
[0190] In the exemplary embodiment shown in FIG. 1, the attritioning of the first solvent extraction stage feed material (132) is performed by mixing the first solvent extraction stage feed material (132) in a first mixing apparatus (140). A purpose of the attritioning is to liberate bitumen from the heavy mineral concentrate (102) so that the bitumen can more effectively be separated from the heavy minerals in the separating of the attritioned first solvent extraction stage feed material (132). Another purpose of the attritioning is to mix the constituents of the first solvent extraction stage feed material (132).
[0191] In the exemplary embodiment shown in FIG. 1, the separating of the attritioned first solvent extraction stage feed material (132) is performed by passing the attritioned first solvent extraction stage feed material (132) through a first gravity settler (142). In the embodiment of FIG. 1, the fast gravity settler (142) is comprised of a first gravity settling vessel.
[0192] In the exemplary embodiment shown in FIG. 1, the second extract (124) is comprised of or consists essentially of the first solvent extraction stage overflow component (138). In the embodiment, of FIG. 1, the first solvent extraction stage underflow component (136) is subjected to the second solvent extraction stage (128).
[0193] The second solvent extraction stage (128) is comprised of attritioning a second solvent extraction stage feed material (144) in order to produce an attritioned second solvent extraction stage feed material (146). The second solvent extraction stage (128) is further comprised of separating the attritioned second solvent extraction stage feed material (146) in order to produce a second solvent extraction stage underflow component (148) and a second solvent extraction stage overflow component (150).
[0194] The second solvent extraction stage feed stage material (144) is composed of the first solvent extraction stage underflow component (136) and includes a second solvent extraction stage amount of a diluent. In the embodiment of FIG. 1, the diluent consists essentially of naphtha. In the embodiment of FIG. 1, the second solvent extraction stage amount of the diluent is at least about 15 percent by weight of the second solvent extraction stage feed material (144). In the embodiment of FIG. 1, the diluent may be comprised of a hydrocarbon diluent which is added in the practice of the invention and/or the diluent may be comprised of a froth treatment diluent which was present in the froth treatment tailings (20).
[0195] In the exemplary embodiment shown in FIG. 1, the second solvent extraction stage feed material (144) may have a solid mineral material concentration of between about 20 percent and about 70 percent by weight of the second solvent extraction stage feed material (144).
[0196] In the exemplary embodiment shown in FIG. 1, the attritioning of the second solvent extraction stage feed material (144) is performed by mixing the second solvent extraction stage feed material (144) in a second mixing apparatus (152). A purpose of the attritioning is to liberate bitumen from the second solvent extraction stage feed material (144) so that the bitumen can more effectively be separated from the heavy minerals in the separating of the attritioned second solvent extraction stage teed material (146). Another purpose of the attritioning is to mix the constituents of the second solvent extraction stage feed material (144).
[0197] In the exemplary embodiment shown in FIG. 1, the separating of the attritioned second solvent extraction stage feed material (146) is performed by passing the attritioned second solvent extraction stage feed material (146) through a second gravity settler (154). In the embodiment of FIG. 1, the second gravity settler (154) is comprised of a second gravity settling vessel.
[0198] In the exemplary embodiment shown in FIG. 1, the second solvent extraction stage overflow component (150) is mixed with the heavy mineral concentrate (102) in the first mixing apparatus (140) so that the first solvent extraction stage feed material (132) is comprised of the second solvent extraction stage overflow component (150). In the embodiment of FIG. 1, the second solvent extraction stage underflow component (148) is subjected to the third solvent extraction stage (130).
[0199] The third solvent extraction stage (130) is comprised of attritioning a third solvent extraction stage feed material (156) in order to produce an attritioned third solvent extraction stage feed material (158). The third solvent extraction stage (130) is further comprised of separating the attritioned third solvent extraction stage feed material (158) in order to produce a third solvent extraction stage underflow component (160) and a third solvent extraction stage overflow component (162).
[0200] The third solvent extraction stage feed material (156) is comprised of the second solvent extraction stage underflow component (148) and includes a third stage amount of a diluent. In the embodiment of FIG. 1, the diluent consists essentially of naphtha. In the embodiment of FIG. 1, the third stage amount of the diluent is at least about 15 percent by weight of the third solvent extraction stage feed material (156). In the embodiment of FIG. 1, the diluent may be further comprised of a hydrocarbon diluent which is added in the practice of the invention and/or the diluent may be comprised of a froth treatment diluent which was present in the froth treatment tailings (20).
[0201] In the exemplary embodiment shown in FIG. 1, the third solvent extraction stage feed material (156) may have a solid mineral material concentration of between about 20 percent and about 70 percent by weight of the third solvent extraction stage feed material (156).
[0202] In the exemplary embodiment shown in FIG. 1, the attritioning of the third solvent extraction stage feed material (156) is performed by mixing the third solvent extraction stage feed material (156) in a third mixing apparatus (166). A purpose of the attritioning is to liberate bitumen from the third solvent extraction stage feed material (156) so that the bitumen can more effectively be separated from the heavy minerals in the separating of the attritioned third solvent extraction stage feed material (158). Another purpose of the attritioning is to mix the constituents of the third solvent extraction stage feed material (156).
[0203] In the exemplary embodiment shown in FIG. 1, the separating of the attritioned third solvent extraction stage feed material (158) is performed by passing the attritioned third solvent extraction stage feed material (158) through a third gravity settler (168). In the embodiment of FIG. 1, the third gravity settler (168) is comprised of a third gravity settling vessel.
[0204] In the exemplary embodiment shown in FIG. 1, the third solvent extraction stage overflow component (162) is mixed with the first solvent extraction stage underflow component (136) in the second mixing apparatus (152) so that the second solvent extraction stage feed material (144) is comprised of the third solvent extraction stage overflow component (162). In the embodiment of FIG. 1, the debitumenized heavy mineral concentrate (122) is comprised of or consists essentially of the third solvent extraction stage underflow component (160).
[0205] In the exemplary embodiment shown in FIG. 1, an addition amount (170) of a hydrocarbon diluent (172) is combined with the second solvent extraction stage underflow component (148) so that the third solvent extraction stage feed material (156) is comprised of the addition amount (170) of the hydrocarbon diluent. In the embodiment of FIG. 1, the hydrocarbon diluent (170) consists essentially of naphtha. In the embodiment of FIG. 1, the addition amount (170) of the hydrocarbon diluent (172) is selected so that the first solvent extraction stage amount of the diluent is at least about 15 percent by weight of the first solvent extraction stage feed material (132).
[0206] The first solvent extraction stage (126) may optionally be further comprised of combining a recycled amount of an intermediate component which is derived from the solvent extraction stage feed material with the feed material so that the feed material is further comprised of the recycled amount of the intermediate component. A purpose of this optional feature is to dilute the solvent extraction stage feed material in order to enhance the separation of the feed material in the second solvent extraction process (120). This optional feature is depicted by dashed lines in FIG. 1. One or more of the solvent extraction stages (126, 128, 130) may be further comprised of this optional feature.
[0207] Referring to the exemplary embodiment shown in FIG. 1, a recycled amount of a first solvent extraction stage intermediate component (174) may optionally be combined with me heavy mineral concentrate (102) so that the first solvent extraction stage feed material (132) is further computed of the recycled amount of the first solvent extraction stage intermediate component (174). The first solvent extraction stage intermediate component (174) is withdrawn from the first gravity settler (142) at a withdrawal point which is located below the level in the first gravity settler (142) where the first solvent extraction stage overflow component (138) accumulates and which is located above the level in the first gravity settler (142) where the first solvent extraction stage underflow component (136) accumulates. The ratio by weight of the recycled amount of the first solvent extraction stage intermediate component (174) to the total amount of the first solvent extraction stage feed material (132) may be in the range of between about 0.1 to about 0.9, and more particularly in the range of between about 0.25 to 0.5
[0208] Referring to the exemplary embodiment shown in FIG. 1, a recycled amount of a second solvent extraction stage intermediate component (176) may optionally be combined with the first solvent extraction stage underflow component (136) so that the second solvent extraction stage feed material (144) is further comprised of the recycled amount of the second solvent extraction stage intermediate component (176). The second solvent extraction stage intermediate component (176) is withdrawn from the second gravity settler (154) at a withdrawal point which is located below the level in the second gravity settler (154) where the second solvent extraction stage overflow component (150) accumulates and which is located above the level in the second gravity settler (154) where the second solvent extraction stage underflow component (148) accumulates. The ratio by weight of the recycled amount of the second solvent extraction stage intermediate component (176) to the total amount of the second solvent extraction stage feed material (144) may be in the range of between about 0.1 to about 0.9, and more particularly in the range of between about 0.25 to about 0.5.
[0209] Referring to the exemplary embodiment shown in FIG. 1, a recycled amount of a third solvent extraction stage intermediate component (178) may optionally be combined with the second solvent extraction stage underflow component (148) so that the third solvent extraction stage feed material (156) is further comprised of the recycled amount of the third solvent extraction stage intermediate component (178). The third solvent extraction stage intermediate component (178) is withdrawn from the third gravity settler (168) at a withdrawal point which is located below the level in the third gravity settler (168) where the third solvent extraction stage overflow component (162) accumulates and which is located above the level in the third gravity settler (168) where the third solvent extraction stage underflow component (160) accumulates. The ratio by weight of the recycled amount of the third solvent extraction stage intermediate component (178) to the total amount of the second solvent extraction stage feed material (156) may be in the range of between about 0.1 to about 0.9, and more particularly in the range of between about 0.25 to about 0.5.
[0210] In some embodiments, the second solvent extraction stage underflow product (148) may be withdrawn from the second gravity settler (154) at a rate that is less than the rate at which the first solvent extraction stage underflow product (136) is withdrawn from the first gravity settler (142). Similarly, in some embodiments, the third solvent extraction stage underflow product (160) may be withdrawn from the third gravity settler (168) at a rate that is less than the rate at which the second solvent extraction stage underflow product (148) is withdrawn from the second gravity settler (154). In embodiments, the ratio of the withdrawal rate of the later solvent extraction stage underflow product (160 or 148) to the withdrawal rate of the earlier solvent extraction stage underflow product (148 or 136, respectively) is in the range of between about 0 to about 1, and more particularly in the range of between about 0.05 to about 0.5.
[0211] Following the second solvent extraction process (120), the second extract (124) may be further processed and/or may be stored or transported for further processing.
First Diluent Recovery Process (180)
[0212] Following the separation process (80), the fine mineral material fraction (84) and the coarse mineral material tailings (104) may each comprise a froth flotation diluent or a hydrocarbon diluent. Consequently, it may desirable to recover at least a portion of the diluent from one or a combination of the fine mineral material fraction (84) and the coarse mineral material tailings (104). A purpose or recovering the diluent is to facilitate recycling of the diluent before further treatment or disposal of the fine mineral material fraction (84) or the coarse mineral material tailings (104). Another purpose is to reduce potential emissions of volatile organic compounds in the diluent and potentially toxic effects of the diluent when the fine mineral material fraction (84) or the coarse mineral material tailings (104) in disposal sites (e.g. tailing ponds).
[0213] As a result, the method of the invention may optionally be further comprised of a first diluent recovery process (180) for recovering an amount of the diluent from the fine mineral material fraction (84) and the coarse mineral material tailings (104) (either individually or in combination referred to as an “first intermediate product” (182)), in order to produce a first diluent recovered intermediate product (184) and a first recovered diluent (186) therefrom. It will be understood that the first intermediate product (182) may comprise either the fine mineral material fraction (84) or the coarse mineral material tailings (104), or a combination of fine mineral material fraction (84) and the coarse mineral material tailings (104).
[0214] In the exemplary embodiment of FIG. 1, recovering an amount of the diluent from the intermediate product (182) is comprised of introducing the intermediate product (182) into a first diluent recovery vessel (183) so that it forms a first intermediate product pool in the first diluent recovery vessel (183), introducing an amount of steam directly into the first intermediate product pool, mixing the resulting first diluted intermediate product which is contained in the first intermediate product pool, and maintaining the first diluted intermediate product in the first diluent recovery vessel (183) for a residence time. The method of recovering the diluent from the first intermediate product (182) and the first diluent recovery vessel (183) may be in accordance with the teachings in Canadian Patent No. 2,768,852 (Moons et al.), the contents of which are herein incorporated by reference.
Second Diluent Recovery Process (188)
[0215] Following the second solvent extraction process (120), the debitumenized heavy mineral concentrate (122) may be further processed to recover the heavy minerals which are contained therein. The debitumenized heavy mineral concentrate (122) may have a bitumen concentration which is no greater than about 0.5 percent by weight of the debitumenized heavy mineral concentrate (122), at which level, the bitumen typically does not interfere significantly with the recovery of heavy minerals front the debitumenized heavy mineral concentrate (122).
[0216] However, the debitumenized heavy mineral concentrate (122) may have a diluent concentration which is about 5 percent or more by weight of the debitumenized heavy mineral concentrate (122). It has been found that a diluent concentration of greater than about 0.5 percent may interfere significantly with the recovery of heavy minerals from the debitumenized heavy mineral concentrate (122). Consequently, it may be desirable to reduce the diluent concentration of the debitumenized heavy mineral concentrate (122) before attempting to recover the heavy minerals therefrom.
[0217] As a result, the method of the invention may optionally further comprise a second diluent recovery process (188) for recovering an amount of the diluent from a second intermediate product (190) comprising the debitumenized heavy mineral concentrate (122) in order to produce a second diluent recovered intermediate product (191) and obtain a second recovered diluent (192) therefrom.
[0218] In the exemplary embodiment of FIG. 1, recovering an amount of the diluent from the second intermediate product (190) is comprised of introducing the second intermediate product (190) into a second diluent recovery vessel (189) so that it forms a second intermediate product pool in the diluent recovery vessel, introducing an amount of steam directly into the second intermediate product pool, mixing the resulting second diluted intermediate product that is contained in the second intermediate product pool, and maintaining the second diluted intermediate product in the second diluent recovery vessel (189) for a residence time. The method of recovering the diluent from the second intermediate product and the second diluent recovery vessel (189) may be in accordance with the teachings in Canadian Patent No. 2,768,852 (Moran et al.), the contents of which are herein incorporated by reference.
Water Recovery Process (194)
[0219] The first diluent recovered intermediate product (184) may comprise water. As a result, it may be desirable to recover at least a portion of the water from the first diluent recovered intermediate product (184), which may be recycled to the process for recovering bitumen from oil sand ore or another process. As a result, the method of the invention may be further comprised of a water recovery process (194) for recovering an amount of water from the first diluent recovered intermediate product (184) in order to produce a recovered water portion (196) and a thickened slurry (198) therefrom.
[0220] In the exemplary embodiment of FIG. 1, the water recovery process (194) comprises of adding a flocculant (200) to the diluent recovered intermediate product (184) in an enhanced gravity separator (202) (e.g., a centrifuge) to flocculate solids in the diluent recovered intermediate product (184), and then subjecting the resultant mixture of flocculated solids and diluent recovered intermediate product (184) to the enhanced gravity separation process to produce the separated water portion (196) and the thickened slurry (198) therefrom. In embodiments, the flocculant may be a polymer-based flocculant that is added to the diluent recovered intermediate product (184) in a concentration in a range of about 200 ppmw to 400 ppmw (parts per million by weight). In embodiments, the recovered water portion (196) may be recovered in elevated temperatures (e.g. about 70 degrees Celsius) and recycled to the process for recovering bitumen from oil sands.
[0221] In embodiments, the water recovery process (194) may further comprise subjecting the thickened slurry (198) to rim ditching and beaching in tailings ponds to recover additional amounts of water from the thickened slurry (198).
[0222] In embodiments, the thickened slurry (198) may be suitable for direct depositing into tailing ponds and other depositional environments. It will be appreciated that reductions in the amount of water in the thickened slurry (198) as compared with the diluent recovered intermediate product (184), may allow for reductions in the volume of material that is discharged to tailings ponds for more effective thickening processes in tailings ponds with a view to accelerating the remediation of tailings ponds.
[0223] In embodiments, the thickened slurry (198) may be suitable for directly subjecting to conventional thin-lift drying to produce trafficable deposits. The reduction in the amount of bitumen in the diluent recovered intermediate product (184) on account of a portion of the bitumen having been removed during the first solvent extraction process (40) may allow for a significant reduction (e.g., less than half) in the amount of flocculant (200) required to produce conventional mature fine tails (MFT). Without restriction to a theory, it is believed that the removal of hydrocarbons from the pre-cursors to the thickened slurry enhances the efficacy of flocculant (200) by removing organic materials that would otherwise contaminate the surface of silica and mineral particles and interfere with the desired effect of the flocculant (200) to induce particle-to-particle attachments.
EXAMPLE
[0224] Referring to FIGS. 2A-2G, collectively, a material balance is provided for a bench scale test simulating the embodiment of the invention depicted by the solid lines in FIG. 1. In FIGS. 2A-2G, all units of mass are expressed in kilograms (kg). The material balance of FIGS. 2A-2G does not include a simulation of the alternate or optional features which are depicted by the dashed lines in FIG. 1. Consequently, in the material balance of FIGS. 2A-2G, the froth flotation process (100) is arranged in a scavenging configuration, and the first solvent extraction process (40) and the second solvent extraction process (120) do not include recycling of the solvent extraction intermediate components (63, 67, 174, 176, 178).
[0225] In the test that is represented by FIGS. 2A-2G the second solvent extraction process (120) was performed by adding “fresh” naphtha as a hydrocarbon diluent in the third solvent extraction stage (130) instead of by recycling the overflow components (150, 162) from the second and third solvent extraction stages (128, 130) respectively. The overflow components (150, 162) were, however, taken into consideration in calculating the material balance of FIGS. 2A-2G. It is believed that the test represented in FIGS. 2A-2G provides a reasonably accurate simulation of the results which could be expected to be achieved if the first through third solvent extraction stages (126, 128, 130) were arranged in an actual countercurrent configuration. Referring to FIG. 2A, the first extract (42), consisting of the first solvent extraction stage overflow component (62), exhibited a water concentration of about 0.50 percent by weight of the first extract (42), exhibited a solid mineral material concentration of about 0.30 percent by weight of the first extract (42), and exhibited a combined water and solid mineral material concentration of about 0.80 percent by weight of the first extract (74).
[0226] Referring to FIG. 2A, hydrocarbon diluent (70) was added in an amount of about 2.50 kg to the forth treatment tailings (20) in the amount of about 5.00 kg and the second solvent extraction stage overflow product (66) in the amount of about 2.78 kg in the first mixer (52) for a solvent to feed ration (S/F) for the first solvent extraction process (40) of about 0.32.
[0227] In FIG. 2A, the parameter “N/B” refers to the naphtha-to-bitumen ratio (on a mass basis) and is determined by dividing the amount of naphtha by the amount of amount of bitumen material for a particular stage of the first solvent extraction process (40) (any discrepancies in the values shown in FIG. 2A attributable to rounding error).
[0228] Referring to FIGS. 2B and 2C, the concentration of heavy minerals (THM) in the solids content of the first raffinate (44) was about 25.18 percent, and the concentration of heavy minerals (THM) in the solids content of the heavy mineral concentrate (102) was about 54.66419 percent.
[0229] Referring to FIG. 2C, the mass of the coarse mineral material fraction (82) was about 2.73 kg and the mass of the heavy mineral concentrate (102) was about 3.50 kg, indicating that the froth flotation process (100) was performed to achieve a mass float of about 55 percent from the coarse mineral material fraction (82).
[0230] Referring to FIGS. 2A and 2D, the bitumen recovery of the first solvent extraction process (40) was about 0.37 kg and of the second solvent extraction process (120) was about 0.02 kg of the original 0.40 kg in the froth treatment railings (20). In other words, the bitumen recovery of the first solvent extraction process (40) is about 92.5 percent, while the bitumen recovery of the second solvent extraction process (120) is about 5 percent, for an overall bitumen recovery of about 97.5 percent.
[0231] Referring to FIG. 2D, the parameter “Asphaltenes” refers to the proportion of bitumen that is comprised of pentane-insoluble hydrocarbon material.
[0232] The parameter “N/B” refers to the naphtha-to-bitumen ratio (on a mass basis) and is determined by dividing the amount of naphtha by the amount of amount of bitumen material for a particular stage of the second solvent extraction process (120) (any discrepancies in the values shown in FIG. 2D attributable to rounding error).
[0233] The parameter “B/S” refers to the bitumen-to-solids mass ratio expressed as a percentage, and is determined by dividing the amount of bitumen by the amount of solids for a particular stage of the second solvent extraction process (120) and multiplying by 100 (any discrepancies in the values shown in FIG. 2D attributable to founding error). The parameter “B/S” reflects the quality of a produced diluted bitumen stream.
[0234] Referring to FIG. 2D, hydrocarbon diluent (170) was added in an amount of about 0.30 kg to a heavy mineral concentrate in an amount of about 1.50 kg, for a solvent to feed ratio (S/F) for the second solvent extraction process of about 0.200167.
[0235] Referring to FIG. 2D, the debitumenized heavy mineral concentrate (122), consisting of the third solvent extraction underflow component (160), exhibited a bitumen concentration of about 0.03 percent by weight of the debitumenized heavy mineral concentrate (122), exhibited a diluent concentration of about 4.49 percent by weight of the debitumenized heavy mineral concentrate (122), and exhibited a water concentration of about 71.96 percent by weight of the debitumenized heavy mineral concentrate (122).
[0236] Referring to FIG. 2D, the debitumenized heavy mineral concentrate (122) contained about 0.31 kg of about 0.32 kg, or in other words about 96.875 percent by weight of the solid mineral material which was contained in the heavy mineral concentrate (102), which suggests that none or very little of the heavy minerals which were contained in the heavy mineral concentrate (102) and which would be included in the solid mineral material were lost in the second solvent extraction process (120).
[0237] Referring to FIGS. 2C and 2D, the second extract (124) contained about 0.01993 kg (rounded to 0.02 kg in FIG. 2D) of about 0.0226 kg (rounded to 0.02 kg in FIG. 2C), or in other words about 88 percent, of the bitumen that was contained in the coarse mineral material fraction (82), indicating a bitumen recovery front the coarse mineral material fraction (82) of about 88 percent
[0238] Referring to FIG. 2F, the diluent recovered debitumenized heavy mineral concentrate (190) exhibited a bitumen concentration of about 0.07 percent by weight of the diluent recovered debitumenized heavy mineral concentrate (190), exhibited a diluent concentration of about 0.08 percent by weight of the diluent recovered debitumenized heavy mineral concentrate (190), and exhibited a water concentration of about 74.11 percent by weight of the diluent recovered debitumenized heavy mineral concentrate (190).
[0239] Referring to FIG. 2F, the diluent recovered debitumenized heavy mineral concentrate (190) contained about 0.31 kg of about 0.31 kg, or in other words, about 100 percent of the solid mineral material which was contained in the debitumenized heavy mineral concentrate (122), suggesting that none or very little of the heavy minerals that were contained in the debitumenized heavy mineral concentrate (122) were lost in the recovery of the diluent from the debitumenized heavy mineral concentrate (122).
[0240] Referring to FIG. 2G, the diluent recovered intermediate product (184) has a solids concentration of about 15.63 percent, whereas the thickened slurry (198) has a solids concentration of about 47.58 percent. The recovered water portion (196) contained about 1.93 kg of about 2.41 kg, or in other words about 80 percent of the water contained in the diluent recovered intermediate product (184). In embodiments, the recovered water portion (196) may comprise 60 to 80 percent by weight of the water in the diluent recovered intermediate product (184). The recovered water portion (196) contained about 1.93 kg of about 3.82 kg, or in other words about 50 percent of water in the froth treatment tailings (20), if make-up water added during the overall process is disregarded. The recovered water portion (196) may be of sufficient quality for re-use as process water.
[0241] In this document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the elements is present, unless the context clearly requires that there be one and only one of the elements.
