SURFACE-MINED OILSANDS

TECHNICAL FIELD

[0001] The present disclosure generally relates to processing bitumen. In particular, the disclosure relates to processing surface-mined bitumen to produce a diluted product-stream with a lower amount of contaminants that can contribute to damage of downstream facilities.

BACKGROUND

[0002] Reserves of oil sands, such as those found in northern Alberta, are typically located within a few hundred feet of the surface or much deeper below the surface. The oil sands that are found relatively close to the surface are mined through open-pit mining processes while the deeper reserves require drilling and in situ recovery technologies.

[0003] Typically oil sands have many constitutive components. For example, oil sands have about 70 to about 90 percent (by weight) mineral solids, such as sand and clay, and about 1 to about 10 percent (by weight) water. The desirable product from the oil sands is bitumen, which is present as an oil fdm that contributes anywhere from a trace amounts to about 21% (by weight) of the oil sands. Reserves with a lower bitumen content tend to have a higher mineral solids content such as smaller pieces of clay and silt, which are referred to as fines.

[0004] In comparison to other refinery crude-oil inputs, including difficult to process heavy- crudes, surface-mined bitumen ore has about 20 times (or higher) solids content, higher asphaltene content and higher chloride content.

[0005] The mining process includes digging up the oil sands and transporting them for processing. Typically the processing includes crushing or comminuting the larger pieces of aggregated oil sands into smaller pieces. Then the smaller pieces are combined with a process fluid to form an“oil-sand slurry” for isolating and recovering the bitumen from the other constitutive components. Hot water is a commonly used process fluid. In some instances, the hot water is heated pond-effluent water (PEW) from a tailings pond. Other agents, such as flotation agents, can also be added to the oil-sand slurry to improve recovery of bitumen from the oil-sand slurry. The oil-sand slurry is then mixed and allowed to dwell to create a froth mixture, during a step referred to as conditioning. The froth mixture is then subjected to one or more separation steps to separate a portion of the bitumen, which is referred to as a bitumen froth, from the other components of the froth mixture. The other components of the froth mixture are typically referred to as tailings. The tailings are transported to ponds for separating the fines, solids and water from each other.

[0006] The separated bitumen-froth is then diluted with a lighter hydrocarbon diluent and transported for extraction, upgrading and refining operations to produce desirable petroleum products. The dilution step produces a diluted separated-bitumen that contains a desirable diluted- bitumen component, a solids component, and an emulsion component. The emulsion component can also be referred to as a“rag” component. The diluted separated-bitumen is then treated, in a process referred to herein as desalting, to separate the diluted separated-bitumen components from each other and to reduce or remove any chemical component that can damage downstream upgrading and refining infrastructure. For example, chloride salts and other ions are known to react with other chemicals to form metal-degrading corrosive agents. Over time the metal-degrading chemical agents degrade the metal infrastructure of the upgrading and refining operations or even infrastructure downstream thereof. Desalting can separate some, most or substantially all of the desirable diluted- bitumen component from the emulsion component and the remaining solids and brine components. The desirable diluted-bitumen can be transported for further upgrading and refining operations. The emulsion component requires further processing steps that are directed at further resolving the emulsion into diluted bitumen and brine.

[0007] At least one complication with processing surface-mined bitumen is that the PEW from tailings ponds can have a high chloride concentration that increases over time as the tailings settle. As such, one or more steps of processing the diluted surface-mined bitumen can actually contribute towards the damage caused to downstream infrastructure. A further complication with processing surface-mined bitumen is that the desalting process may not sufficiently resolve the solids content from the other components of the diluted separated-bitumen, which can promote fouling and erosion within downstream infrastructure.

SUMMARY

[0008] Implementations of the present disclosure relate to a process for treating surface- mined bitumen. The process comprises the steps of: diluting surface-mined bitumen ore for producing diluted surface-mined bitumen; treating the diluted surface-mined bitumen with one or more chemicals for producing a desalting feed stream; separating at least a portion of the desalting feed stream to a desalted bitumen band, an emulsion band and a brine-and-solids band within a vessel, wherein the desalted bitumen band has a lower salt concentration than the diluted surface-mined bitumen; and, applying an electric field to the desalted bitumen band. The process further includes an adjustment step and includes one or more steps of: adjusting a desalted bitumen withdrawal rate from the vessel; adjusting an emulsion withdrawal rate from the vessel; and, adjusting a brine-and- solids withdrawal rate from the vessel, for maintaining a desired distance between the emulsion band and the electric field.

[0009] Further resolving of the middle emulsion band can reduce the salt and solids content within the desalted-bitumen output. Further resolving of the middle emulsion band can also reduce the middle emulsion band outflow from the vessel, which in turn can reduce the costs associated with further treating the emulsion band outflow. Implementations of the present disclosure facilitate resolution of the middle emulsion band by maintaining the desired distance between the middle emulsion band and the electric field while reducing or avoiding any tripping of the electric field.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Implementations of the present disclosure and features thereof will become more apparent in the following detailed description. The detailed description in which reference is made to the appended drawings, which illustrate by way of example only:

[0011] FIG. 1 is a schematic that shows an example of a system for processing surface-mined bitumen, according to implementations of the present disclosure;

[0012] FIG. 2 is a schematic that shows an example of system for processing surface-mined bitumen, according to implementations of the present disclosure;

[0013] FIG. 3 shows a cross-sectional view of a desalting vessel according to implementations of the present disclosure;

[0014] FIG. 4 is a partial, cross-sectional view of a desalting vessel, according to implementations of the present disclosure, along the longitudinal axis and the insert image is an example of a density profile sensor output display;

[0015] FIG. 5 is a schematic of a system with a controller and a desalting vessel according to implementations of the present disclosure;

[0016] FIG. 6 is data acquired from the system, wherein FIG. 6A shows one test run where the electrostatic-grid tripped; and, FIG. 6B shows another test run where the electrostatic grid was stable;

[0017] FIG. 7 is a schematic of an example of an emulsion-treatment process; and [0018] FIG. 8 is a schematic that represents steps of an example of a method for processing surface-mined bitumen, according to implementations of the present disclosure.

DETAILED DESCRIPTION

[0019] Definitions

[0020] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0021] As used herein, the term“about” refers to an approximately +/-l0% variation from a given value. The person skilled in the art understands that such a variation is always included in any given value provided herein, whether or not it is specifically referred to.

[0022] As used herein, the terms “conduct”, “conducted”, “communicate” and

“communicated” can be used interchangeably to refer to the movement of a fluid, and any fluid entrained therein, from one place to another place.

[0023] As used herein, the term“input” refers to a process stream that is entering a discrete process-step of a larger, multiple step process.

[0024] As used herein, the term“output” refers to a process stream that is a product of a discrete process step of a larger, multiple step process. An output can also be referred to as an input upon entry into another discrete process-step.

[0025] As used herein, the terms“emulsion” and“rag” can be used interchangeably in reference to a mixture of at least bitumen, water, solids and salts.

[0026] As used herein, the terms“resolution”,“resolving” and“resolve” refer to a process whereby an emulsion that includes diluted, surface-mined bitumen and at least some water is destabilized to separate the diluted, surface-mined bitumen and the water. In some instances, resolving the emulsion also separates salts within the emulsion from the diluted, surface-mined bitumen. The salts can separate with the water and exit via either or both of a rag stream and a brine stream.

[0027] FIG. 1 shows an example of a system 2 for processing surface-mined bitumen. In general, the arrows in FIG. 1 represent one or more conduits that conduct fluid inputs and outputs through the various components of the system 2. A source of surface-associated bitumen 8 is surface mined to extract surface-mined bitumen ore. The person skilled in the art will understand that the surface-mined bitumen ore includes various chemical components, many of which are not desirable for downstream upgrading or refining processes 500. For example, in some implementations of the present disclosure the surface-mined bitumen ore has a high solids content and/or a chloride concentration (present either as a chloride salt or a chloride containing chemical compound) of between about 50 and 250 parts per million (ppm). The presence of chloride in bitumen can corrode, deteriorate or otherwise damage downstream infrastructure. The source of the chloride in the surface- mined bitumen is typically connate water that is associated with the surface-mined bitumen ore. The surface-mined bitumen can also be exposed to extraction steps 10 and 12 (discussed further below) to provide a diluted, surface-mined bitumen input stream 100 with an American Petroleum Institute gravity (API) of between about 15 and 35 and so that a stream of diluted surface-mined bitumen can be conducted through one or more pipes at a temperature of between about 125 degrees Fahrenheit (°F) and about 340 °F and at a pressure of between about 85 to 165 pounds per square inch gage (PSIG). The diluted, surface-mined bitumen input stream 100 can have a solids content of between about 0.15 weight percent (wt%) and 0.8 wt%.

[0028] Within the system 2, the surface-mined bitumen ore is subjected to a first extraction step 10. During the first extraction step 10 the surface-mined bitumen ore is washed with solvent to remove some of the undesirable sand components from the desired surface-mined bitumen. The solvent can be fresh water, heated water, heated or unheated pond-effluent-water (PEW) that is taken from one or more tailings ponds.

[0029] The washed, surface-mined bitumen ore is conducted 98 to a second extraction and diluting step 12. The second extraction and diluting step 12 can include one or more steps of centrifugation or exposure to an inclined plate separator to further extract the desired surface-mined bitumen. The second extraction and diluting step 12 also includes a step of diluting (shown as 136 in FIG. 2) the surface-mined bitumen with lighter-chained hydrocarbons. The diluting step 136 improves the surface-mined bitumen’s fluidity by reducing viscosity. Naptha and other similar length hydrocarbons are often used as diluents in the dilution step 136. The dilution step 136 produces a diluted, surface-mined bitumen input stream 100 that is conducted to a diluted-bitumen storage tank 14. The diluted, surface-mined bitumen 100 is then conducted 102A from the diluted-bitumen storage tank 14 to a diluent recovery unit 18. A pump 16 is used during the conducting step 102 A to increase the flow rate and/or pressure of the diluted, surface-mined bitumen stream 100. In some implementations of the present disclosure, the diluted surface-mined bitumen stream 100 has a chloride concentration (present either as a chloride salt or a chloride containing chemical compound) of between about 5 and 60 parts per million (ppm). The source of the chloride in the surface-mined bitumen stream 100 is typically connate water that is associated with the surface-mined bitumen. However, the PEW added in the first extraction step 10 can have a much higher chloride concentration, which adds to the total chlorides in the diluted, surface-mined bitumen input stream 100. For example, the PEW can have a chloride concentration of between about 50 ppm to about 2500 ppm.

[0030] FIG. 1 also shows three desalting vessels 20A, 20B and 20C. The desalting vessel

20A is positioned upstream of the diluted, surface-mined bitumen storage tank 14 in fluid communication with the diluted, surface-mined bitumen input stream 100 that is being conducted towards the storage tank 14. The desalting vessel 20B is positioned downstream of the storage tank 14 and upstream of the diluent recovery unit 18. The desalting vessel 20C is positioned within the diluent recovery unit 18. Implementations of the system 2 of the present disclosure include one, two or all three of the desalting vessels 20A, 20B and 20C. Each desalting vessel 20A, 20B and 20C perform a desalting step 120. In all the above configurations, the desalting process can also be operated without the use of any wash water, during what is referred to as“Treater” mode. The Treater mode involves less processing equipment, which may incur less capital costs at the expense of operating costs that are associated with higher diluted bitumen losses to an emulsion stream and/or a brine stream, as discussed further below. The Treater mode can provide a viable alternative configuration mode that depends on the water concentration within the diluted, surface-mined bitumen and the overall objectives of the processing performed by the system 2.

[0031] When the desalting vessel 20A is included in the system 2, a first desalted-bitumen stream 150A (shown with a hashed line in FIG. 1) is the input into the storage tank 14. In this implementation, the output from the storage tank 14 can also be the first desalted bitumen stream 150A.

[0032] When the desalting vessel 20B is included, a second desalted-bitumen stream 150B

(shown with a hashed line in FIG. 1) can be an input stream for the diluent recovery unit 18.

[0033] When the desalting vessel 20C is included, athird desalted-bitumen stream 150C (also shown with a hashed line in FIG. 1) can be one of the outputs from the diluent recovery unit 18 that is conducted towards upgrading and further refining processes.

[0034] The second bitumen stream 150B can have a lower salt content than the first bitumen stream 150A. Similarly, the third bitumen stream 20C can have a lower salt content that the first bitumen stream 150A and, if present, the second bitumen stream 150B.

[0035] It is understood that one, two, three or more desalting vessels 20 can be used in the system 2. In some implementations of the present disclosure, the desalting vessels 20A, 20B and 20C can be configured in series, in parallel or any combination thereof. The first desalting vessel 20A can be upstream of the storage tank 14 or not. Also, the third desalting vessel 20C can be independent of the diluent recovery unit 18 or not.

[0036] Some implementations of the present disclosure relate to a desalting vessel 20A that includes a mud wash input 138 can be introduced into the desalting vessel 20A to wash at least a portion of the solids that settle in the bottom of the desalting vessel 20A (see FIG. 2). The washed solids form a mud wash output stream 140 that exits the desalting vessel 20A. The desalting process within the desalting vessel 20A can also result in some off-gasing, which is vacated from the desalting vessel 20A by an off-gas output 139.

[0037] FIG. 2 shows further processing steps that can be performed in the system 2, or not.

For example, wash water 30 can be conducted 130 into the diluted, surface-mined bitumen 100. The wash water 30 can also be used during the first extraction step 10. The diluted, surface-mined bitumen can again be washed 130A with water, which can be referred to as plant process water. A heating unit 23 can be positioned upstream of the desalting vessel 20A. The heating unit 23 can increase the temperature of the diluted, surface-mined bitumen to between about 130 ° F and about 360 °F. A mixing unit 24 can be positioned upstream of the desalted unit 20A and, if present, downstream of the heating unit 23. The mixing unit 24 mixes the diluted, surface-mined bitumen in preparation for entering the desalting vessel 20 A.

[0038] Optionally, the system 2 can also perform a first chemical addition step 132. During the first chemical addition step 132 one or more aqueous chemicals 32 are added to the wash water 30 that can be used in the first extraction step 10. For example, the one or more aqueous chemicals 32 can include, but are not limited to: a solids -wetting agent, a mineral wetting chemical; a pH modifier, a water-dispersible demulsifier and combinations thereof. Without being bound by any particular theory, the aqueous chemicals make the solids that are exposed thereto more water wettable and more separable from the other components of the diluted, surface-mined bitumen. Modifying the pH with aqueous pH modifiers can help clarify the brine stream resolve the emulsion layer.

[0039] The system 2 can also perform a second chemical addition step 134. During the second chemical addition step 134 one or more non-aqueous chemicals 34 are added to the surface-mined bitumen stream 100. For example the one or more non-aqueous chemicals can include, but are not limited to: a demulsifier; an ashphaltene dispersant, an emulsion-compression chemical, a solids- wetting agent and combinations thereof. Without being bound by any particular theory, the non- aqueous demulsifiers can reduce the water content of the diluted surface-mined bitumen. Further, the asphaltene dispersants and the emulsion-compressor chemical can help resolve the emulsion. [0040] The discussion of the desalter vessel 20A is also applicable to each of the desalting vessels 20B and 20C. In some implementations of the present disclosure, the desalting vessel 20A is a vessel with a length of between about 18 to about 22 feet (a foot is equivalent to about 0.3048 meters). In some implementations of the present disclosure, the desalting vessel 20A is cylindrical with an outer diameter (OD) of about 6 to 20 feet. In other implementations of the present disclosure, the desalting vessel 20A is also cylindrical with a length of between about 100 feet and about 120 feet with an OD of about 14 feet. In other implementations of the present disclosure, the desalting vessel 20A is substantially the same size or larger than desalting vessels typically used in the oil-and- gas industry.

[0041] The desalting step 120 that occurs within the desalting vessel 20A separates chloride salts, water and solids from the diluted, surface-mined bitumen. The diluted, surface-mined bitumen input stream 100, which may also be referred to herein as a desalting feed stream 100, enters the desalting vessel 20A by an input header 200, as shown in FIG. 3 and discussed further below. Within the desalting vessel 20A, the diluted, surface-mined bitumen input stream 100 separates into a three bands: (i) an upper desalted-bitumen band 202; (ii) a middle emulsion band 204; and (iii) a lower brine-and-solids band 206. The upper desalted-bitumen band 202 and the middle emulsion band 204 together define an upper interface 210. The middle emulsion band 204 and the lower brine-and-solids band 206 together define a lower interface 212.

[0042] The upper desalted-bitumen band 202 is removed from the vessel by a desalted- bitumen output port 214 (or multiple ports that are fluidly connected by a header) as a desalted- bitumen stream 102 that is conducted downstream to the further upgrading or refinement processes 500. The desalted-bitumen stream 102 has a lower salt content than the desalting feed stream 100. In some implementations of the present disclosure, the desalted-bitumen stream 102 can be removed from the desalting vessel 20A constantly and optionally at different rates over time. In some implementations of the present disclosure, about 20% and about 50% of the chlorine from the diluted, surface-mined bitumen input can remain in the desalted output stream 102. The lower brine-and- solids band 206 can be further separated into a high solids content output stream 140 and a brine output stream 146. The high solids content output stream 140 can exit the desalting vessel 20A from a solids output port 228. The brine output stream 146 can exit the desalting vessel 20A by a brine output port 230 (or multiple ports that are fluidly connected by a header).

[0043] The middle emulsion band 204 can be removed from the desalting vessel 20A as an emulsion output stream 143 that exits the desalting vessel 20A by an emulsion output port 232 (or multiple ports that are fluidly connected by a header). In some implementations of the present disclosure, an emulsion output stream 142 band can be removed from the desalting vessel 20A constantly and optionally at different rates over time. The emulsion output stream 142 is conducted for further emulsion processing in an emulsion treatment 42 to separate the emulsion output stream 142 into further process streams that can be further processed within the system 2. As shown in FIG. 2, in some implementations of the present disclosure the emulsion treatment 42 produces at least one of: a first processed emulsion stream 144A; a second emulsion process stream 144B; and a third emulsion process stream 144C. The first emulsion process stream 144A can be re-introduced into the system 2 upstream of the desalting vessel 20. The second processed emulsion stream 144B is mostly, if not completely, made up of diluted bitumen. The second processed emulsion stream 144B is introduced into the desalted bitumen output stream 102. The third processed emulsion stream 144C is typically incapable of further separating for or for producing further useful process streams. The third processed emulsion stream 144C can be stored, further processed internally or disposed of according to local environmental regulations.

[0044] FIG. 3 shows one example of the emulsion output port 232 which is arranged with one or more internal elongate output pipes (not shown) that are positioned at or about the vertical level of where the middle-emulsion band 204 is within the desalting vessel 20A. In some implementations of the present disclosure there are two emulsion output ports 232 that are vertically displaced from each other. For example, there can be an upper emulsion output port 232A and a lower emulsion port 232B. The upper and lower emulsion ports 232A, 232B are fluidly connected to a common header pipe. In some implementations of the present disclosure the vertically displaced upper and lower emulsion ports 232A, 232B can reduce a coning effect that draws desalted-bitumen from the upper desalted-bitumen band 202 through the middle emulsion band 204. The coning effect can lead to unnecessary wastage and a greater need for reprocessing and recycling of the desalted bitumen within the emulsion output stream 142. The emulsion ports 232A, 232B can minimize this coning effect by being tuned via one or more flow-control valves 233 that are positioned on either or both of the upper emulsion port 232A and the lower emulsion port 232B. As discussed further below information about the profile of the middle emulsion band 204 can be acquired and used to control the flow-control valves to minimize the coning effects to smooth out any sudden manipulations of the emulsion output stream 142 flow rates.

[0045] As shown in FIG. 3, the desalting vessel 20A also includes an electrostatic array 300 that is positioned in an upper portion of the desalter vessel 20A so that the electrostatic array 300 is within the upper desalted-bitumen band 202 when the desalter vessel 20A is in use. The electrostatic array 300 generates an adjustable electric field. In some implementations of the present disclosure, the electrostatic array 300 can include a vertically-arranged electrostatic grid with one or more parallel conductive plates. In other implementations of the present disclosure, the electrostatic array 300 has at least one and optionally multiple horizontally-arranged electric grids. For example, the electrostatic array 300 can have with an upper grid 302, a middle grid 304 and a lower grid 306. It is appreciated by those skilled in the art that the electrostatic array 300 can include more or less grids than the three shown in FIG. 3.

[0046] In some implementations of the present disclosure the lower grid 306 provides a first portion of the electric field that has a lower voltage than the other horizontally-arranged grids and the upper grid 302 and the middle 304 have the same voltage or not. For example, the lower grid 306 can have a voltage between 0.5 kilovolts (kV) and 12 kV; the middle grid 304 provides a second portion of the electric field that can have a voltage between about 2 kV and about 10 kV; and the upper grid 302 provides a third portion of the electric field that can have a voltage between about 5 kV and about 22 kV. The electrostatic array 300 creates an electric field that can be a weak alternating current (AC) field that contributes towards resolution of the middle emulsion band 204 into the upper desalted-bitumen band 202 and the lower brine-and-solids band 206. In some implementations of the present disclosure, the lower grid 306 has a greater relative contribution towards resolving the middle emulsion band 204 and either or both of the middle grid 304 and the upper grid 302 have a greater relative contribution to dehydrating the desalted-bitumen band 202. In some implementations of the present disclosure, the electric field can be AC, a direct current (DC) or a combination thereof.

[0047] FIG. 4 shows a density-profile sensor 238 that is vertically positioned within the desalting vessel 20 A. The density-profile sensor 238 extends from proximate to an upper wall to proximate a lower wall of the desalting vessel 20A. The density-profile sensor 238 measures the surrounding fluids to determine the position of the upper desalted-bitumen band 202, the middle emulsion band 204 and the lower brine-and-solids band 206. In some implementations of the present disclosure the density-profile sensor 238 can be a TRACERCO PROFILER® (TRACERCO PROFLIER is a registered trademark of the Johnson Matthey Public Limited Company), a similar analyzer that is commercially available, for example from VEGA America Inc., or any other density profile sensor or analyzer that is or becomes available. By understanding the position of the bands 202, 204, 206 using the density -profile sensor 238 within the desalting vessel 20A relative to the stationary components of the desalting vessel 20A the position of the upper interface 210 can be adjusted so that the middle emulsion band 204 is a desired distance from the electric field of the electrostatic array 300 but not too close to the lower grid 306. If the middle emulsion band 204 is close to the weak AC electric field then there can be greater resolution of the middle emulsion band 204. However, if the middle emulsion band 204 is too close to the lower grid 306 when the water content within the middle emulsion band 204 can cause the electrostatic grid 300 to draw excessive amps, which can cause the electrostatic array 300 to trip. Understanding where the middle emulsion band 204 is relative to the lower grid 306 can allow the desired adjustment of the inputs and outputs of the desalting vessel 20 to maintain and/or optimize the desired distance that the middle emulsion band 204 is from the electric field for optimizing resolution of the middle emulsion band 204, reducing the instance of the electrostatic array tripping. For example, the rate at which the lower brine-and-solids band 206 is removed from the desalting vessel 20A can provide further vertical space within the desalting vessel 20A for the middle emulsion band 204. If the middle emulsion band 204 increases in height that can increase the overall residence time of the middle emulsion band 204 and the exposure time to the electric field of the electrostatic array 300. As shown in the insert in FIG. 4, the positions that are lower (indicated as the numbers in the right hand side of the insert which represent a position above the bottom wall (in inches) of the desalting vessel 20A show an increased presence of water or an increased presence of solids, as indicated by the higher values of about or greater than 860 kg/m ³ (shown in the left hand side of the insert). This value represents an example of a threshold value that can be used to determine the position of the upper interface 210 above the bottom wall and, therefore, the position of the upper interface 210 relative to the lower grid 306. The information provided by the density-profile sensor 238 can also be used to provide height and density information regarding the middle emulsion layer 204.

[0048] In some implementations of the present disclosure the desalting vessel 20A can also include a chemical input line 450 for introducing chemicals, such as an acid water-wash, into the desalting vessel 20A (see FIG. 5). The chemical input line 450 can be in fluid communication with the conduit that is providing the diluted, surface-mined bitumen input stream 100 into the desalter vessel 20A. In some implementations of the present disclosure, the acidified wash-water can be introduced into the middle emulsion band 204 via the upper emulsion output port 232A in a direction that is opposite to the flow direction of the emulsion into the upper emulsion output port 232A, which can help destabilize the middle emulsion band 204 and minimize or substantially eliminate the need to draw the middle emulsion band 204 out of the desalting vessel 20A.

[0049] FIG. 5 shows an example of a system 400 that includes a controller 401 for receiving information from the desalting vessel 20A and for instructing components of the desalting vessel 20 A. The controller 401 can be a programmable logic controller (PLC), a multi-variable process controller (MPC) or both that can monitor and control various functions of the desalting vessel 20A so as to achieve a desired resolution of the middle emulsion band 204. For example, the controller 401 can be any one of a commonly available personal computer or workstations having a processor, volatile and non-volatile memory, and an interface circuit for interconnection to one or more peripheral devices for data input and output. Processor-executable instructions, in the form of application software, can be loaded into memory in the controller 401 to adapt its processor have various I/O ports that can receive information from the desalting vessel 20 A.

[0050] The information from the desalting vessel 20A that is received by the controller 401 includes but is not limited to: density profde sensor information 402, electronic information 404 from the electrostatic array 300 including but not limited to the voltage potential across the electrostatic array 300, or each individual grid 302, 304, 306; the amps being drawn by the electrostatic array 300, or each individual grid 302, 304, 306. The controller 401 can also receive an information input 406 from one or more other sensors or from a user 406A that relates to the status and operation of the system 400. Based upon the information input 402, 404 and/or 406 received, the controller 401 can send messages to a display 410 and the user provide operator instructions 406B can act upon this information, as described further below, or the controller 401 can take one or more automated actions, as described further below.

[0051] The input 406 to the controller 401 can include information about the emulsion output stream 142 that is provided by one or more emulsion output sensors 427. The one or more emulsion output sensors 427 can provide: on-line density information about the emulsion output stream 142 and/or flow information, including rates and/or volumes, about the emulsion output stream 142 and the chemical profde of the emulsion output stream 142. The input 406 can also include information about the brine output stream 146 that is provided by one or more brine output sensors 425. The one or more brine output sensors 425 can provide: flow information, including rate and/or volumes, of the brine output stream 146 and/or a chemical profde of the brine output stream 146. For example, the one or more brine output sensors 425 can include an on-line chloride analyser that analyzes the chloride content of the brine output stream 146 and that on-line chloride information can also be provided to the controller 401 via input 406.

[0052] Based upon the controller 401 receiving some or all of the above inputs 402, 404 and

406 regarding the status and operation of the system 400, the controller 401 can control the height of the upper interface 210 between the middle emulsion band 204 and the upper desalted bitumen band 202 to maintain the amps drawn by the electrostatic array 300 within a desired range to avoid tripping of the electrostatic array 300. Other control functions of the controller 401 can include, but are not limited to: maintaining or adjusting the wash-water ratio, the voltage potential of each of the horizontally-arranged grids 302, 304, 306, the rate at which chemicals are introduced into the desalter vessel 20A; the flow-control valves 233 on the rag draw are part of the constraint settings within the MPC application. The impact of each input and output on the objective function/ controls is tested, as part of the MPC program development [0053] In some implementations of the present disclosure the controller 3401 can control the effective conductivity of the middle emulsion band 204 by controlling the water content of the middle emulsion band 204. By controlling one or both of the upper interface 210 and the conductivity of the middle emulsion band 204, the controller 401 can allow the upper interface 210 to approach the electrostatic grid 300 while avoiding having the electrostatic grid 300 trip, which can increase the resolution of the middle emulsion band 204.

[0054] In some implementations of the present disclosure, controller 401 controls the height of the upper interface 210 between the middle emulsion band and the upper desalted bitumen band to keep the amps drawn by the electric grid, and in turn the grid voltage, within a desired range by manipulating primarily the rag draw rate. In addition, it could adjust the wash water and chemical injection rates/ratios to control rag formation to optimize the overall objective function, depending on the specific site limitations. Actuating the flow-control valves 233 on the emulsion output ports 232 can also form part of the mechanism by which the controller 401 operates to control the operation of the desalting vessel 20 A.

[0055] In another implementation of the present disclosure, the desalting vessel 20A includes one or more controllable valves. For example, the desalting vessel 20A can include a desalted- bitumen output valve 426 that controls the rate or pressure of the flow of the desalted-bitumen output stream 102. The controller 401 can send instructions 418 to the valve 426 to open, close or modulate the valve 426 to achieve a desired flow of desalted bitumen out of the desalting vessel 20A. The system 400 can also include an emulsion output valve 420 that controls the rate of the flow of the emulsion output stream 142. The controller 401 can send instructions 412 to open, close or modulate the valve 420 to achieve a desired rate or pressure of the emulsion output stream 142 flow. The system 400 can also include a brine output valve 424 that can be controlled by an instruction 414 from the controller 401 to achieve a desired rate of the brine output stream 146 flow. The system 400 can also include a chemical input valve 422 that controls an input of chemicals 416 into the desalting vessel 20A. The controller 401 can send instructions 416 to the valve 422 to increase or decrease the input of one or more chemicals into the desalting vessel 20A. The chemicals can influence the resolution of the middle emulsion band 204. For example, the chemical can be one or more of an acid, an asphaltene dispersant, a solids wetting agent, a rag compression agent, a demulsifier agent or combinations thereof into the desalting vessel can increase the resolution of the middle emulsion band 204. [0056] The valves 420, 422, 424 and 426 can be controlled by one or more of an electronic positioner, a pneumatic actuator, a hydraulic actuator or an electronic solenoid each of which respond to instructions 412, 414, 416, 418 respectively from the controller 401.

[0057] In some implementations of the present disclosure, the controller 401 receives both water content information 406 A about the diluted, surface-mined bitumen stream 100 and electronic information 404. This information is compared against specific operator instructions 406B and/or memory-stored information within the controller 401 to maintain the position of the upper interface 210 proximal to the lower grid 306 by controlling the efflux of the brine output stream 146 through valve 424. FIG. 6A shows the data acquired over a 40 hour test run of the system 400. A line 600 shows an example of water content data (%) as determined by a water analyzer that measures the diluted, surface-mined bitumen input stream 100. Line 602 shows the efflux of the emulsion output stream 142. Line 604 shows the amps drawn by the electrostatic grid 300. FIG. 6A shows that as the water content rose above a set point (about 2.5-3 vol%, see A in FIG. 6A) the amps rose in spite of the increased efflux of the emulsion output stream 142 from the desalting vessel 20 A. The increased amp draw resulted in the electrostatic array 300 tripping. Once the water content decreased the electrostatic array 300 was reset and the amp draw was substantially constant.

[0058] FIG. 6B shows a second 40 hour test run of the system 400 where the water content in line 600 twice rose above a set point of 3.5% (see B and C) yet the amp draw (line 604) was relatively stable. The difference between the first test run and the second test run are attributed at least towards identifying the position of the upper interface 210 using the density profile sensor 238 information and regulating the emulsion output stream 142 so that the position of the upper interface 210 was substantially stable. Without being bound by any particular theory, the information from the density profile sensor 238 can be used to establish a set point for determining the withdrawal rate of either or both of the emulsion output stream 142 and the brine output stream 146. The controller 401 effectively controls the position of the upper interface 210 in such a way to keep the amps draw by the electrostatic grid 300 within a desirable range by controlling the effective conductivity (i.e. water content) of the middle emulsion band 204 within the electric field below the electrostatic array 300.

[0059] Some implementations of the present disclosure relate to the use of one or more centrifuges as part of the emulsion treatment 42. As shown in FIG. 7, the system 2 can include a conduit for directing the emulsion output stream 142 from one or more of the desalting vessels 20 A, 20B, 20C (shown collectively as 20 in FIG. 7) to the emulsion treatment 42. For example, the emulsion output stream 142 is conducted to a first centrifuge 500. The first centrifuge 500 is configured to separate the emulsion output stream 142 into a water output stream 142A, an oil output stream 142B and a solids output stream 142C by centrifugal force. The water output stream 142A can form the first processed emulsion stream 144A, which can be conducted back upstream of the desalting vessel 20 for further processing therethrough. The oil output stream 142B can be fluidly communicated with, or it can form, the second processed emulsion stream 144B, which in turn can be fluidly communicated with the desalted-bitumen stream 102. The solids output stream 142C can be fluidly communicated with, or it can form, the third emulsion process stream 144C.

[0060] The centrifuge 500 is configured to separate the emulsion output stream 142 into the output streams 142A, 142B and 142C. In some implementations of the present disclosure, the centrifuge 500 is one or more of: a vertically-oriented decanter centrifuge, a horizontally-oriented decanter centrifuge, a conveyor-type decanter centrifuge, a solid-wall separator disc-stack centrifuge, a self-cleaning disc-stack centrifuge, a nozzle separator disc-stack centrifuge or combinations thereof. In some implementations of the present disclosure, the centrifuge 500 is preferably a horizontally- oriented decanter centrifuge.

[0061] In some implementations of the present disclosure, the emulsion treatment 42 optionally includes a source of one or more chemicals 502 (shown in a hashed-line box in FIG. 7) that can be added to the emulsion output stream 142 upstream of the centrifuge 500. In some implementations of the present disclosure, the one or more chemicals 502 can be added to the emulsion output stream 142 by an injection step that is powered by a pump (not shown) before the emulsion output stream 142 is treated with the centrifuge 500. The one or more chemicals 502 can be one or more of: a solids-wetting agent, a mineral wetting chemical; a pH modifier, a demulsifier; a rag-compressing agent; an ashphaltene dispersant, an emulsion-compression agent; a flocculant; solids releasing agent; a solids-wetting agent or combinations thereof. In some implementations of the present disclosure, the one or more chemicals 502 includes as least one of a polymer-based flocculant, a demulsifier and a solids releasing agent. In some implementations of the present disclosure, the polymer-based flocculant is BASF 8190, the demulsifier is Tretolite DM08825U, BPR 27141 or combinations thereof and the solids release agent is Jettison 3000. The person skilled in the art will appreciate that these specific chemicals are provided as examples only and not as limitations on the suitability of using other chemicals in the emulsion treatment 42.

[0062] In some implementations of the present disclosure, the emulsion treatment 42 optionally includes a further centrifuge 504 (shown in a hashed-line box in FIG. 7) that is in series with the centrifuge 500. The further centrifuge 504 is configured to receive and process the oil output stream 142B from the centrifuge 500 by a step of further centrifugation. The further centrifuge 504 separates the oil output stream 142B into a further oil output stream 143 and a water and solids output stream 145. The further oil output stream 143 can be fluidly communicated with, or it can form, the second processed emulsion stream 144B. The water and solids output stream 145 can be further processed to extract some or all of the remaining water content by known processes and the remaining output can be fluidly communicated with, or it can form, the third processed emulsion stream 144C.

[0063] In some implementations of the present disclosure, the emulsion treatment 42 optionally includes a source of one or more further chemicals 506 (shown in a hashed-line box in FIG. 7) that can be added to the oil output stream 142B upstream of the further centrifuge 504. In some implementations of the present disclosure, the one or more further chemicals 506 can be added to the oil output stream 142B by an injection step that is powered by a further pump (not shown) before the oil output stream 142B is treated with the further centrifuge 504. The one or more further chemicals 506 can be one or more of: a solids-wetting agent, a mineral wetting chemical; a pH modifier, a demulsifier; a rag-compressing agent; an ashphaltene dispersant, an emulsion- compression agent; a flocculant; solids releasing agent; a solids-wetting agent or combinations thereof.

[0064] FIG. 8 shows one example of a method 600 for processing surface-mined bitumen.

The method 600 includes the step of diluting 602 surface-mined bitumen ore for producing diluted surface-mined bitumen. The diluted surface mined-bitumen is subjected to a step of treating 604 with one or more chemicals for producing a desalting feed stream. The method 600 includes a step of separating 606 at least a portion of the desalting feed stream into a desalted bitumen band, an emulsion band and a brine-and-solids band within a vessel. The desalted bitumen band has a lower salt concentration than the diluted surface-mined bitumen. The method includes a step of applying 608 an electric field to the desalted bitumen band and a step of adjusting 610 one or more of: a desalted bitumen withdrawal rate from the vessel; an emulsion withdrawal rate from the vessel; and a brine- and-solids withdrawal rate from the vessel. The step of adjusting 610 is for maintaining a desired distance between the emulsion band and the electric field for example, to avoid shorting out the source of the electric field while facilitating resolution of the emulsion band.

[0065] In some implementations of the present disclosure, step of adjusting 610 can include a step of increasing or decreasing 612 one or more of the desalted bitumen withdrawal rate, the emulsion withdrawal rate or the brine-and-solids withdrawal rate.

[0066] In some implementations of the present disclosure, the method 600 includes a step of separating 614 the brine-and-solids band into a high solids content output stream and a brine output stream within the vessel. [0067] In some implementations of the present disclosure, the method 600 includes a step of adding 618 a chemical to the vessel for increasing resolution of the middle emulsion band. In some implementations of the present disclosure, the chemical that is added in step 618 is an acid, an asphaltene dispersant, a solids wetting agent, a rag-compressing agent, a demulsifier agent or a combination thereof. In some implementations of the present disclosure, the chemical is added into or proximal to the middle emulsion band within the vessel.

[0068] In some implementations of the present disclosure, the step of applying 608 the electric field includes adjusting 620 the electric field to have a voltage between about 0.5 kilovolts (kV) and about 12 kV. The step of adjusting 620 can also include a step of providing 622 a second portion of the electric field with a voltage of between about 2 kV and about 10 kV. The second portion of the electric field is positioned within the vessel above a first portion of the electric field that has the voltage of between about 0.5 kV and about 12 kV. In some implementations of the present disclosure, the step of applying 622 the electric field further comprises a step of providing 624 a third portion of the electric field with a voltage of between about 5 kV and about 22 kV. The third portion of the electric field is positioned within the vessel above the second portion. In some implementations of the present disclosure, the electric field is applied as an alternating current.

[0069] In some implementations of the present disclosure, the method 600 includes a further step of determining 626 the position of the emulsion band relative to the electric field.

[0070] In some implementations of the present disclosure, the method 600 includes a step of directing the emulsion output stream 142 from one or more of the desalting vessels 20A, 20B, 20C (shown collectively as 20 in FIG. 7) to the emulsion treatment 42 for a step of centrifugation that separates the emulsion output stream into a water output stream, an oil output stream and a solids output stream. The water output stream can be conducted back upstream of the desalting vessel 20 for further processing therethrough. The oil output stream can be fluidly communicated with, or it can form, the second processed emulsion stream 144B, which in turn can be fluidly communicated with the desalted-bitumen stream 102. The solids output stream 142C can be fluidly communicated with, or it can form, the third emulsion process stream 144C.

[0071] In some implementations of the present disclosure, the method 600 includes a step of adding one or more chemicals to the emulsion output stream upstream of the centrifuge 500. In some implementations of the present disclosure, the one or more chemicals 502 can be added to the emulsion output stream 142 by an injection step that is powered by a pump (not shown) before the emulsion output stream 142 is treated with the centrifuge 500. The one or more chemicals 502 can be one or more of: a solids-wetting agent, a mineral wetting chemical; a pH modifier, a demulsifier; a rag-compressing agent; an ashphaltene dispersant, an emulsion-compression agent; a flocculant; solids releasing agent; a solids -wetting agent or combinations thereof. The person skilled in the art will appreciate that these specific chemicals are provided as examples only and not as limitations on the suitability of using other chemicals in the emulsion treatment 42.

[0072] In some implementations of the present disclosure, the method 600 optionally includes a further centrifugation step of the oil output stream from the earlier centrifugation step. The step of further centrifuge separates the oil output stream into a further oil output stream and a water and solids output stream. The further oil output stream can be fluidly communicated with, or it can form, the second processed emulsion stream. The water and solids output stream can be further processed to extract some or all of the remaining water content by known processes and the remaining output can be fluidly communicated with, or it can form, the third processed emulsion stream 144C.

[0073] In some implementations of the present disclosure, the method 600 includes a step of adding one or more further chemicals to the oil output stream upstream of the further centrifugation step. In some implementations of the present disclosure, the one or more further chemicals can be added to the oil output stream by an injection step. The one or more further chemicals can be one or more of: a solids-wetting agent, a mineral wetting chemical; a pH modifier, a demulsifier; a rag compressing agent; an ashphaltene dispersant, an emulsion-compression agent; a flocculant; solids releasing agent; a solids-wehing agent or combinations thereof.