Patent Publication Number: US-2019194546-A1

Title: Methods for removing bitumen from tar sands

Description:
BACKGROUND 
     A large amount of the world&#39;s oil supply may be found in tar sands. Tar sands, commonly referred to as “oil sands”, are generally a combination of clay, sand, water, and bitumen, which is a highly viscous mixture including hydrocarbons. Tar sands can be mined and processed to extract the bitumen, which may then be further refined into usable products such as gasoline, diesel, and various forms of petrochemicals. 
     As bitumen may not be pumped from the ground in its natural state, the extraction of bitumen from the tar sands may be more complex in some aspects than conventional oil recovery. In at least one extraction process, tar sand deposits are mined using strip mining or open pit techniques. The tar sands are transported to an extraction plant, where heat is applied to the tar sands and the tar sands are agitated, resulting in the separation of the bitumen from the remainder of the tar sands. Although effective, the aforementioned extraction process requires a heat source and energy to power the heat source, which increases the operating costs of the extraction plant. 
     What is needed, therefore, is a process to remove bitumen from tar sands that may be carried out without the addition of thermal energy from a thermal energy source, thereby reducing operating costs associated with the removal of bitumen from tar sands. 
     SUMMARY 
     Embodiments of the disclosure may provide a method for removing bitumen from tar sands. The method may include contacting the tar sands with a hydrocarbon. The method may also include contacting the tar sands including the hydrocarbon with a water soluble silicate. The method may further include separating the tar sands into a liquid portion and a solid portion, the liquid portion including the water soluble silicate and the bitumen. The method may also include separating the water soluble silicate from the bitumen. 
     Embodiments of the disclosure may further provide a method for removing bitumen from tar sands. The method may include crushing the tar sands in a crusher to form a crushed tar sand. The method may also include contacting the crushed tar sand with a hydrocarbon to form a first mixture. The method may further include contacting the first mixture with a water soluble silicate at ambient temperature to form a second mixture. The method may also include separating the second mixture into a first liquid portion, a second liquid portion, and a solid portion. The method may further include contacting the first mixture with the first liquid portion. 
     Embodiments of the disclosure may further provide a method for removing bitumen from tar sands. The method may include crushing the tar sands in a crusher to form a crushed tar sand. The method may also include conveying the crushed tar sand to a first mixer. The method may further include contacting the crushed tar sand with a hydrocarbon in the first mixer to form a first mixture. The method may also include conveying the first mixture to a second mixer. The method may further include contacting the first mixture with a water soluble silicate at ambient temperature in the second mixer to form a second mixture. The method may also include separating the second mixture into a first liquid portion, a second liquid portion, and a solid portion. The method may further include feeding the first liquid portion to the second mixer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure is best understood from the following detailed description when read with the accompanying Figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. 
         FIG. 1  illustrates a schematic of a system for removing bitumen from tar sands, according to one or more embodiments. 
         FIG. 2  is a flowchart depicting a method for removing bitumen from tar sands, according to one or more embodiments. 
         FIG. 3  is a flowchart depicting a method for removing bitumen from tar sands, according to one or more embodiments. 
         FIG. 4  is a flowchart depicting a method for removing bitumen from tar sands, according to one or more embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     It is to be understood that the following disclosure describes several exemplary embodiments for implementing different features, structures, or functions of the invention. Exemplary embodiments of components, arrangements, and configurations are described below to simplify the present disclosure; however, these exemplary embodiments are provided merely as examples and are not intended to limit the scope of the invention. Additionally, the present disclosure may repeat reference numerals and/or letters in the various exemplary embodiments and across the Figures provided herein. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various exemplary embodiments and/or configurations discussed in the various Figures. Moreover, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact. Finally, the exemplary embodiments presented below may be combined in any combination of ways, i.e., any element from one exemplary embodiment may be used in any other exemplary embodiment, without departing from the scope of the disclosure. 
     Additionally, certain terms are used throughout the following description and claims to refer to particular components. As one skilled in the art will appreciate, various entities may refer to the same component by different names, and as such, the naming convention for the elements described herein is not intended to limit the scope of the invention, unless otherwise specifically defined herein. Further, the naming convention used herein is not intended to distinguish between components that differ in name but not function. Additionally, in the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to.” All numerical values in this disclosure may be exact or approximate values unless otherwise specifically stated. Accordingly, various embodiments of the disclosure may deviate from the numbers, values, and ranges disclosed herein without departing from the intended scope. Furthermore, as it is used in the claims or specification, the term “or” is intended to encompass both exclusive and inclusive cases, i.e., “A or B” is intended to be synonymous with “at least one of A and B,” unless otherwise expressly specified herein. 
       FIG. 1  illustrates a schematic of a system  100  for removing bitumen from tar sands, according to one or more embodiments of the present disclosure. The tar sands may be removed from the earth at various depths via one or more removal processes. For example, the tar sands at shallow depths (e.g., less than about 70 meters to about 75 meters) may be removed from the earth via mining. The mining of the tar sands may be carried out via strip mining or open pit mining after the mineable areas are cleared of trees, shrubs, and/or other land vegetation. In open pit mining, a layer of earth, referred to as the overburden, may be removed and an open pit is created. Tar sand deposits may be located near the surface of the earth in the open pit and heavy machinery including hydraulic and electrically powered rope shovels may be used to dig up and load the tar sands into trucks or other like transport vehicles for the removal of the tar sands from the open pit. 
     As illustrated in  FIG. 1 , the tar sands may be transported from an open pit  102  to the system  100 , which may be located at the site of the mining operations, e.g., the open pit  102 , or adjacent thereto in one or more embodiments. The present disclosure is not limited thereto, and in other embodiments, the system  100  may be located at a site remote from the mining operations. In yet another embodiment, one or more of the components of the system  100  may be located at one or more remote locations from at least one other component of the system  100 , where trucks, or other suitable transport means, may be provided to operatively connect the components of the system  100 . 
     Although not illustrated in detail in the schematic of  FIG. 1 , the system  100  may include a hopper or like receptacle configured to receive the tar sands removed from the open pit  102  and transported from the transport vehicles. The transported tar sands may be in lump form, where a plurality of lumps of the tar sands may be introduced to the hopper. The hopper may be further configured to funnel or otherwise direct the lumps of tar sands to a crusher  104  adjacent to and, in some embodiments, coupled to the hopper and configured to break, crush, grind, or otherwise reduce the lumped tar sands to a crushed tar sand. In one or more embodiments, the crusher  104  may be a sizer or grinder. The crushed tar sand may be or include a plurality of loose tar sand particles. It will be appreciated that the contactable surface area of the tar sands is increased as the lumped tar sands are reduced in size to loose tar sand particles. 
     The crushed tar sand may exit the crusher  104  and may be dumped onto or otherwise disposed on a conveyer or like transport device. In the example embodiment illustrated in  FIG. 1 , the system  100  may include a mixer  106  operatively coupled to the conveyor and configured to receive the crushed tar sand discharged from the crusher  104 . Although not illustrated, in at least one embodiment, a storage component (e.g., silo, stockpile, surge bin) may be operatively coupled to the crusher  104  and the mixer  106  and may be configured to store the crushed tar sand prior to the introduction thereof to the mixer  106  in the event of a shutdown or otherwise temporary interruption of the bitumen removal process. In at least one embodiment, the crushed tar sand may be further screened via a screener (not shown) prior to introduction to the mixer  106  in order to remove any oversized material (e.g., rocks, ice, or petrified wood intermixed with the crushed tar sand) not sufficiently crushed in the crusher  104 . The removed oversized material may be transported back to the crusher  104  or sent to a waste pile (not shown) depending on the composition of the oversized material. 
     As illustrated in  FIG. 1 , the crushed tar sand may be fed from the conveyor into the mixer  106 , where the crushed tar sand may be contacted by a solvent to “pre-treat” the crushed tar sand. The mixer  106  may be, for example, a paddle mixer. In other embodiments, the mixer may be a drum mixer, a tumble mixer, and the like. In one or more embodiments, the solvent may be a hydrocarbon supplied by a hydrocarbon source  108  fluidly coupled to the mixer  106 . The hydrocarbon source  108  may be located on site or may provide the hydrocarbon to the mixer  106  via one or more pipelines and related conduits. The hydrocarbon source  108  may be, for example, a hydrocarbon well, a hydrocarbon storage tank, or a pipeline. In one or more embodiments, the hydrocarbon may be condensate, gasoline, diesel, or combinations thereof. The hydrocarbon from the hydrocarbon source  108  may be introduced into the mixer  106  automatically or manually. In the event the hydrocarbon is introduced automatically, a control system (not shown) may be provided to monitor, weigh, determine the flow volume of, and distribute the hydrocarbon to the mixer  106  as desired. The amount of hydrocarbon contacting the crushed tar sand may be a function of the weight or volume of the crushed tar sand introduced to the mixer  106 . 
     The hydrocarbon may be introduced to the mixer  106  and may contact the crushed tar sand fed thereto. The contacting of the hydrocarbon with the crushed tar sand, in addition to the mixing or agitation provided by the mixer  106 , may result in the separation of a portion of the bitumen from the crushed tar sand. Accordingly, a pre-treated mixture may be formed including the hydrocarbon, the portion of the bitumen removed from the crushed tar sand, and the crushed tar sand. 
     The system  100  may also include another mixer  110  downstream from and operatively coupled to the mixer  106 . The pre-treated mixture may be a slurry in at least some embodiments and may be discharged from the mixer  106  and conveyed to the mixer  110  via a pipeline or like conduit. A slurry pump (not shown) may be utilized to convey the pre-treated mixture from the mixer  106  to the mixer  110 . In the mixer  110 , the pre-treated mixture may be contacted by an aqueous solution including a water soluble silicate to further separate the bitumen and hydrocarbon solvent from the crushed tar sand. The mixer  110  may be, for example, a paddle mixer. In other embodiments, the mixer  110  may be a drum mixer, a tumble mixer, and the like. 
     In one or more embodiments, the water soluble silicate may be a sodium silicate. In another embodiment, the water soluble silicate may be a potassium silicate. In yet other embodiments, the water soluble silicate may be a zirconium silicate or a magnesium silicate. The aqueous solution including the water soluble silicate may be supplied by an aqueous solution source  112  fluidly coupled to the mixer  110 . The aqueous solution source  112  may be located on site or may provide the aqueous solution to the mixer  110  via one or more pipelines and related conduits. The aqueous solution source  112  may be, for example, an aqueous solution storage tank, a pipeline, a separator discussed in further detail below, or a combination thereof. The aqueous solution source  112  and the conduits fluidly coupled thereto may be insulated. 
     The aqueous solution including the water soluble silicate may be introduced into the mixer  110  automatically or manually. In the event the aqueous solution including the water soluble silicate is introduced automatically, a control system (not shown) may be provided to monitor, weigh, determine the flow volume of, and distribute the aqueous solution including the water soluble silicate to the mixer  110  as desired. The amount of aqueous solution including the water soluble silicate contacting the pre-treated mixture may be a function of the weight or volume of the pre-treated mixture introduced to the mixer  110 . 
     The aqueous solution including the water soluble silicate may be introduced to the mixer  110  and may contact the pre-treated mixture fed thereto. The aqueous solution including the water soluble silicate at ambient temperature may be introduced to the mixer  110 , thereby providing for the absence of a heat source in the system  100 . By omitting a heat source and the addition of thermal energy in the system  100 , the operating costs and footprint of the system  100  may be reduced. The contacting of the aqueous solution including the water soluble silicate with the pre-treated mixture, in addition to the mixing or agitation provided by the mixer  110 , may result in the separation of substantially all of the remaining portion of the bitumen from the pre-treated mixture. Accordingly, a three phase mixture may be formed including the hydrocarbon and the bitumen removed from the pre-treated mixture, the aqueous solution including the water soluble silicate, and the crushed tar sand. In one or more embodiments, the portion of the bitumen removed from the crushed tar sand may be about 90% to about 99% of the bitumen originally present in the crushed tar sand. In another embodiment, the portion of the bitumen removed from the crushed tar sand may be about 95% to about 99% of the bitumen originally present in the crushed tar sand. 
     The system  100  may further include one or more separators (two shown  114  and  116 ) configured to separate the three phase mixture. In the embodiment illustrated in  FIG. 1 , the system  100  may include a liquid-solid separator  114  operatively coupled to the mixer  110  via a pipeline or like conduit and configured to separate the crushed tar sand from the aqueous solution including the water soluble silicate, the hydrocarbon, and the bitumen. Examples of suitable liquid-solid separators  114  may include a gravity separator, a centrifugal separator, a filter, and a hydrocyclone. The separated solid portion (crushed tar sand) may be referred to as “tailings” and may be discharged from the liquid-solid separator  114  and disposed on a shaker (not shown) to further separate any remaining liquids from the solids. The crushed tar sand after removal of the bitumen and any remaining liquids after separation may be a clean sand having an increased crush strength as compared to the tar sand excavated from the open pit  102 . The clean sand may be suitable for use in a variety of applications. For example, the clean sand may be used as backfill for the open pit  102  to return the land to a trafficable landscape. In another example, the clean sand may be used as frac sand. 
     The separated liquid portion from the liquid-solid separator  114  may be transported via a pipeline or like conduit to a liquid-liquid separator  116  fluidly coupled to the liquid-solid separator  114 . The liquid-liquid separator  116  may be configured to separate the hydrocarbon and bitumen from the aqueous solution including the water soluble silicate. Examples of suitable liquid-liquid separators  116  may include a gravity separator, a centrifugal separator, a filter, and a hydrocyclone. The aqueous solution including the water soluble silicate may be separated from the hydrocarbon and bitumen and returned to the aqueous solution source  112  and subsequently reintroduced to the mixer  110 . In at least one embodiment, the aqueous solution including the water soluble silicate may be separated from the hydrocarbon and bitumen and transported directly back to the mixer  110 . The separated hydrocarbon and bitumen may be transported to a storage tank  118  (illustrated in  FIG. 1 ) located in a tank farm or to another processing component or facility for refining purposes. 
     Although not illustrated, in another embodiment, the three-phase mixture may be separated in a single, three-phase separator, thereby reducing the number of components in the system  100  and further reducing costs and maintenance of the system. The three-phase separator may be configured to separate the three-phase mixture into a solid portion (crushed tar sand), a first liquid portion (aqueous solution including the water soluble silicate) and a second liquid portion (hydrocarbon and bitumen). After separation, each of the separated portions may be directed in the manners disclosed above with respect to the liquid-solid separator  114  and the liquid-liquid separator  116 . 
     Turning now to  FIG. 2  with continued reference to  FIG. 1 ,  FIG. 2  is a flowchart depicting a method  200  for removing bitumen from tar sands, according to one or more embodiments. The method  200  may include contacting the tar sands with a hydrocarbon, as at  202 . The method  200  may also include contacting the tar sands including the hydrocarbon with a water soluble silicate, as at  204 . In one or more embodiments, the water soluble silicate may be selected from sodium silicate, zirconium silicate, magnesium silicate, and potassium silicate. The method  200  may further include separating the tar sands into a liquid portion and a solid portion, as at  206 . The liquid portion may include the water soluble silicate and the bitumen. The method  200  may also include separating the water soluble silicate from the bitumen, as at  208 . In at least one embodiment, contacting the tar sands with the water soluble silicate may further include contacting the tar sands with at least a portion of the water soluble silicate separated from the bitumen. 
     In one or more embodiments, the method  200  may also include crushing the tar sands. In one or more embodiments, the hydrocarbon contacting the tar sands may be selected from condensate, diesel, and gasoline. In one or more embodiments, the hydrocarbon contacting the tar sands may be diesel. In one or more embodiments, the method  200  may also include excavating the tar sands from a tar sand deposit located proximal the surface of the earth. 
     Turning now to  FIG. 3  with continued reference to  FIG. 1 ,  FIG. 3  is a flowchart depicting a method  300  for removing bitumen from tar sands, according to one or more embodiments. The method  300  may include crushing the tar sands in a crusher to form a crushed tar sand, as at  302 . The method  300  may also include contacting the crushed tar sand with a hydrocarbon to form a first mixture, as at  304 . The method  300  may further include contacting the first mixture with a water soluble silicate at ambient temperature to form a second mixture, as at  306 . The method  300  may also include separating the second mixture into a first liquid portion, a second liquid portion, and a solid portion, as at  308 . The method  300  may further include contacting the first mixture with the first liquid portion, as at  310 . 
     In one or more embodiments, the first liquid portion may be the water soluble silicate, and the second liquid portion may include the hydrocarbon and the bitumen. In one or more embodiments, the water soluble silicate may be selected from sodium silicate, zirconium silicate, magnesium silicate, and potassium silicate. In one or more embodiments, the hydrocarbon may be selected from condensate, diesel, and gasoline. 
     In one or more embodiments, the method  300  may also include directing the first liquid portion to a storage tank containing the water soluble silicate, and directing the water soluble silicate from the storage tank to a mixer containing the first mixture. In one or more embodiments, separating the second mixture into the first liquid portion, the second liquid portion, and the solid portion further includes: separating the solid portion from a mixture of the first liquid portion and the second liquid portion in a first separator; feeding the mixture of the first liquid portion and the second liquid portion to a second separator; and separating the first liquid portion and the second liquid portion in the second separator. In at least one other embodiment, separating the second mixture into the first liquid portion, the second liquid portion, and the solid portion may be carried out in a three-phase separator. 
     Turning now to  FIG. 4  with continued reference to  FIG. 1 ,  FIG. 4  is a flowchart depicting a method  400  for removing bitumen from tar sands, according to one or more embodiments. The method  400  may include crushing the tar sands in a crusher to form a crushed tar sand, as at  402 . The method  400  may also include conveying the crushed tar sand to a first mixer, as at  404 . The method  400  may further include contacting the crushed tar sand with a hydrocarbon in the first mixer to form a first mixture, as at  406 . The method  400  may also include conveying the first mixture to a second mixer, as at  408 . The method  400  may further include contacting the first mixture with a water soluble silicate at ambient temperature in the second mixer to form a second mixture, as at  410 . The method  400  may also include separating the second mixture into a first liquid portion, a second liquid portion, and a solid portion, as at  412 . The method  400  may further include feeding the first liquid portion to the second mixer, as at  414 . 
     In one or more embodiments, the method  400  may also include directing the first liquid portion to a storage tank containing the water soluble silicate, and directing the water soluble silicate from the storage tank to a mixer containing the first mixture. In one or more embodiments, separating the second mixture into the first liquid portion, the second liquid portion, and the solid portion further includes: separating the solid portion from a mixture of the first liquid portion and the second liquid portion in a first separator; feeding the mixture of the first liquid portion and the second liquid portion to a second separator; and separating the first liquid portion and the second liquid portion in the second separator. In at least one other embodiment, separating the second mixture into the first liquid portion, the second liquid portion, and the solid portion may be carried out in a three-phase separator. 
     In one or more embodiments, the first liquid portion may be the water soluble silicate, and the second liquid portion may include the bitumen and the hydrocarbon. In one or more embodiments, the water soluble silicate may be selected from sodium silicate, zirconium silicate, magnesium silicate, and potassium silicate. In one or more embodiments, the solid portion may include a clean sand having a greater crush strength than a crush strength of the tar sand prior to the removal of the bitumen therefrom. In one or more embodiments, feeding the first liquid portion to the second mixer further includes feeding the first liquid portion to a storage tank including the water soluble silicate, and feeding the water soluble silicate including the first liquid portion to the second mixer. 
     The foregoing has outlined features of several embodiments so that those skilled in the art may better understand the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure.