BITUMEN DROPLETS COALESCENCE

Abstract

A process is provided for treating an aqueous oil sand slurry containing bitumen droplets and air bubbles prior to separation in a separator, comprising separating the aqueous oil sand slurry into at least two individual slurry streams and allowing the at least two slurry streams to collide with one another such that the bitumen droplets and air bubbles in each slurry stream make contact with one another to increase both collision frequency and efficiency, and providing sufficient residence time to allow the bitumen droplet to coalesce, grow, and aerate to produce a treated oil sand slurry with larger and lighter bitumen droplets to improve bitumen flotation and recovery.

Claims

1. A process for treating an aqueous oil sand slurry containing bitumen droplets and air bubbles prior to separation in a separator, comprising: (a) separating the aqueous oil sand slurry into at least two individual slurry streams; (b) allowing the at least two slurry streams to collide with one another such that the bitumen droplets and air bubbles in each slurry stream make contact with one another to increase both collision frequency and efficiency; and (c) providing a residence time to allow the bitumen droplets to coalesce, grow, and aerate to produce a treated oil sand slurry with larger and lighter bitumen droplets to enhance bitumen flotation and recovery.

2. The process as claimed in claim 1, further comprising introducing the treated oil sand slurry into a separation zone for forming a bitumen froth.

3. The process as claimed in claim 1, wherein the at least two slurry streams collide in a mixing vessel.

4. The process as claimed in claim 3, wherein the residence time in the mixing vessel is in a range of about 2 minutes to about 5 minutes.

5. The process as claimed in claim 1, wherein the at least two slurry streams collide in a pipeline.

6. The process as claimed in claim 1, wherein the aqueous oil sand slurry has been previously conditioned in a pipeline.

7. The process as claimed in claim 1, wherein the aqueous oil sand slurry has been previously conditioned in a tumbler.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG. 1 illustrates four different embodiments of the present invention in panels (a) to (d).

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0022] The invention is exemplified by the following description and examples.

[0023] The present invention is directed to the coalescence and aeration of bitumen droplets. In order for bitumen droplets to coalesce, two key steps must occur: (1) the droplets must collide, and (2) once they have collided the interfacial forces must be of the nature to promote the coalescence of the two droplets. Without being bound by theory, it is believed that droplet coalescence frequency () is the product of the collision efficiency (.sub.c) and the collision frequency (.sub.c). The collision frequency is the number of encounters between droplets per unit time per unit volume.

[0024] Thus, in accordance with the present invention, any factor that increases the collision frequency is likely to increase droplets coalescence. In a conventional hydrotransport pipeline, the bitumen droplets and air bubbles essentially travel in the same direction or in parallel. Thus, the probability for these droplets and bubbles to collide with one another is low. The efficiency of bitumen droplets coalescence and aeration in such a pipeline is consequently limited.

[0025] It was discovered that one way to improve the efficiency of bitumen droplets coalescence and aeration is to create at least two streams of oil sand slurry (generally from a single stream) and remix these streams in such a way to increase bitumen-bitumen and bitumen-bubble collision frequency/efficiency and/or local droplet/bubble concentration to enhance bitumen droplets coalescence and aeration. In one embodiment, two streams of oil sand slurry can travel in opposite directions, thereby allowing the two streams to collide with one another. In another embodiment, two oil sand slurry streams may travel across each other (e.g., collide perpendicularly to one another).

[0026] When the at least two streams meet each other, the droplets and bubbles in one stream will collide with those in the other stream. Thus, the bitumen droplets do not need to deviate from the streamlines and displace the intervening liquid layer in order to collide with other droplets/bubbles, as would be required in the case of where there is only one oil sand slurry stream in which droplets and bubbles travel in parallel. As a result of multiple streams of oil sand slurry colliding with one another, the efficiency of bitumen droplets coalescence and aeration will be improved.

[0027] FIG. 1 consists of four panels (a) to (d), where each panel illustrates an embodiment of the present invention for creating two oil sand slurry streams to enhance bitumen droplets coalescence and aeration. In the three embodiments shown in panel (a), panel (b), and panel (c), the two streams meet at a point where the droplets/bubbles in one stream will collide with those from the other stream travelling in a perpendicular direction. Panel (d), is an embodiment where two streams travel in opposite directions.

[0028] Tests were performed using the embodiment shown in panel (a) of FIG. 1. More particularly, a stream of conditioned oil sand slurry was separated into two streams and the two streams were allowed to collide with one another perpendicularly in a stirred mixer with a residence time of at least 2 to 5 minutes to produce treated oil sand slurry of the present invention. The treated oil sand slurry was then subjected to bitumen separation in a separation vessel. The resulting bitumen recovery increased by 20% as compared to bitumen froth obtained from untreated oil sand slurry (i.e., from the single stream of conditioned oil sand slurry).

[0029] The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to those embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the full scope consistent with the claims, wherein reference to an element in the singular, such as by use of the article a or an is not intended to mean one and only one unless specifically so stated, but rather one or more. All structural and functional equivalents to the elements of the various embodiments described throughout the disclosure that are known or later come to be known to those of ordinary skill in the art are intended to be encompassed by the elements of the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.