BLENDING MINED OIL SAND ORES FOR BITUMEN EXTRACTION OPERATIONS
A process and process line for mining and blending a plurality of different grade oil sand ore is provided comprising forming an open stockyard for blending and stockpiling the different grades of oil sand ore, whereby the blending of the different grades of oil sand ore is managed by haul trucks dumping the different grades of oil sand ore at a dispatched coordinate either on the perimeter of the stockyard or in the stockyard pit.
The present invention relates to mining technology and, in particular, decoupling real-time mining of oil sand ore from bitumen extraction operations to enable favorable oil sand ore blending by using a stockyard where blending and storing of oil sand ores can occur.
BACKGROUND OF THE INVENTIONOil sand ore, such as is mined in the Fort McMurray region of Alberta, generally comprises water-wet sand grains held together by a matrix of viscous bitumen. Typically, a “low grade” oil sand ore will contain between about 6 to 10 wt. % bitumen with about 25 to 35 wt. % fines. An “average grade” oil sand ore will typically contain at least 10 wt. % bitumen to about 12.5 wt. % bitumen with about 15 to 25 wt. % fines and a “high grade” oil sand ore will typically contain greater than 12.5 wt. % bitumen with less than 15 wt. % fines. “Fines” are generally defined as those solids having a size less about 44 μm.
Oil sand lends itself to liberation of the sand grains from the bitumen, preferably by slurrying the oil sand with heated water, allowing the bitumen to move to the aqueous phase. For many years, the bitumen in the McMurray sand has been commercially removed from oil sand using what is commonly referred to in the industry as the “hot water process”. In general terms, the hot water process involves dry mining the oil sand at a mine site that can be kilometers from an extraction plant; transporting the as-mined oil sand in large ore trucks to a primary crushing plant; conveying the crushed ore to a slurry preparation plant where the oil sand is mixed with hot water, caustic (e.g., sodium hydroxide) and naturally entrained air to yield an oil sand slurry; “conditioning” the oil sand slurry (for example, in a hydrotransport pipeline) so that lumps of oil sand are ablated or disintegrated, the released sand grains and separated bitumen flecks are dispersed in the water where the bitumen flecks coalesce and grow in size, and the bitumen flecks may contact air bubbles and coat them to become aerated bitumen; and removing the bitumen froth from the slurry in an extraction plant comprising one or more separators (for example, a primary separation vessel or PSV).
Currently, most oil sand mining operations use trucks and shovels to mine the oil sand ore from the mine face and transport the mined ore to a primary crusher/slurry preparation plant. To date, most primary crushers and slurry preparation plants are fixed, i.e., not readily relocatable. In the applicant's mining operation, the average haul distance is currently 4-5 km. However, future ore bodies would require truck hauls of 10-20 km to existing primary crusher locations. Thus, the costs of mining will be increasing due to the long distances and outward migration of mining faces away from fixed plants. The reliance on “on-time delivery” of ore from haul trucks and the need to apply appropriate ore blending prior to slurry preparation makes it ever more difficult to manage costs. Hence, the truck and shovel mining operation may suffer from lower productivity due to these two constraints.
Under present operations, oil sand ore blending occurs in “real time”, i.e., when the haul trucks unload the ore into the primary crusher. This is done to ensure a continuous supply of ore to the slurry preparation plant. Since most crushers can only accommodate two truckloads (payloads) of ore at a time, one can only achieve a 50-50 blend of two ores. However, there are instances when further blending would be optimal to achieve the desired processability of the ore. Thus, the extraction operation suffers from lower recovery due to less than optimum ore blending.
In the face of ever-increasing presence of poorer ore grades, ore blending has become even more important to maintain acceptable bitumen recovery rates. However, as currently practiced, mining productivity suffers because of the increased demand for improved ore blending. Thus, there is a need in the industry for improved ore blending without sacrificing mining productivity.
In addition, under present operations, trucks are often queued up to make sure the right blend of ore is obtained. However, this can result in wait times of up to three minutes or more which may result in a loss of up to 200,000 payloads of opportunity. Thus, there is a further need in the industry to decouple the mining operation from the extraction operation to avoid wait times for haulers to dump their load.
Finally, the present invention allows for the placement of haul destinations closer to the active mine area.
SUMMARY OF THE INVENTIONThe present invention is directed to a process and process line that effectively decouples ‘real-time’ oil sand ore mining from bitumen extraction operations to enable quality oil sand ore blending. Thus, the present invention may result in one or more of the additional benefits: lower capital costs; lower operating costs; lower relocation costs; compact and readily placed ‘in-pit’; and minimal construction area lead time (i.e. no civil mega-projects).
In one aspect, a process line is provided for mining and blending oil sand ore, comprising:
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- a plurality of shovels for mining oil sand ore at least two separate mine faces, wherein at least one shovel is mining oil sand at a first mine face and at least one shovel is mining oil sand at a second mine face;
- a plurality of haul trucks for receiving oil sand ore, whereby at least one haul truck is receiving oil sand ore from a shovel mining at the first mine face and at least one haul truck is receiving oil sand ore from a shovel mining at the second mine site;
- an open stockyard for blending and stockpiling the oil sand ore, where blending of oil sand ore is managed by each haul truck dumping at a dispatched coordinate on the perimeter of the stockyard; and
- a device which moves the oil sand ore from the perimeter of the stockyard into the stockyard to form at least one stockpile of blended ore.
Hence, once the at least one stockpile is formed, the blended ore from the stockpile can be continuously fed to a primary crusher for crushing prior to oil sand slurry preparation at a slurry preparation plant. The at least one stockpile is then continuously replenished with new ore being delivered by the haul trucks.
In one embodiment, it may be desirable to have the stockyard located at or near the mine face. In this embodiment, it is preferable that the primary crusher is a semi-mobile crusher. In one embodiment, the slurry preparation plant is also relocatable.
In another aspect, a method for blending at least two different oil sand ores, each oil sand ore having a different grade, is provided, comprising:
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- providing at least one haul truck for each oil sand ore for delivering the oil sand ore to a designated area;
- mapping out a grid on the designated area indicating locations where each ore sand ore is to be deposited;
- mixing the oil sand ore in the designated area to form a stockpile comprising a substantially uniform grade of blended oil sand ore.
Referring to the drawings wherein like reference numerals indicate similar parts throughout the several views, several aspects of the present invention are illustrated by way of example, and not by way of limitation, in detail in the following figures. It is understood that the drawings provided herein are for illustration purposes only and are not necessarily drawn to scale.
The detailed description set forth below in connection with the appended drawings is intended as a description of various embodiments of the present invention and is not intended to represent the only embodiments contemplated by the inventor. The detailed description includes specific details for the purpose of providing a comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.
As used herein, “semi-mobile” equipment refers to equipment that is designed to be relatively easy to relocate (i.e., relocateable) but which generally does not move on a regular hourly or daily basis as mobile shovels and trucks do.
In the embodiment shown in
Oil sand slurry prepared in the semi-mobile compact slurry preparation unit 9 can then be transported and conditioned in hydrotransport pipeline 28. Hydrotransport pipeline 28 is generally around 3 km in length, its length being sufficient to ensure proper conditioning of the oil sand slurry. Thus, hydrotransport pipeline 28 receives oil sand slurry from semi-mobile compact slurry preparation unit 9, transports the slurry while simultaneously conditioning it, and, optionally, delivers the conditioned slurry to a screening assembly 40 for removing a portion of the coarse solids, in particular, clay lumps and rocks, therefrom. Screening assembly 40 comprises a slurry screen for scalping/removal of wear-inducing lumps in the conditioned slurry down to a nominal size (e.g. about 12 to 15 mm and larger is removed). Screening assembly 40 may be relocatable by means of tracks 27. In one embodiment, the screening assembly 40 may be positioned further upstream, i.e., along the hydrotransport pipeline 28, before the oil sand slurry is fully conditioned. There may be instances where it is more desirable to remove the clay lumps and rocks as soon as possible, so there will be an optimal screening assembly location, where oil sand lumps have been ablated just below the screen cut size, for example, 1.5-2.5 km from the start of the hydrotransport pipeline 28.
The screened slurry 28 can optionally be further desanded using a semi-mobile solids removal assembly 29 for removing coarse sand therefrom. In one embodiment, semi-mobile desanding assembly 29 comprises a near pit desander (NPD), or separator, as described in Canadian Patent Application No. 2,809,959. In this embodiment, NPD is moveable by means of tracks 37. It is understood, however, that other moveable desanders or desanding circuits can be used.
The semi-mobile desanding assembly 29 produces a relatively clean (i.e., relatively free from bitumen) coarse solids underflow 31, which only needs to be transported a short distance to sand storage 32. The reduced solids upper zone or overflow 30 comprises bitumen, fines and water and is amenable to long distance transport through a pipeline to a bitumen extraction plant for polishing/water reheat and return. It was discovered that desanded oil sand slurry could be pumped long distances, has a lower power constraint and produces low wear on downstream equipment.
Operating cost for a slurry pumping system is relative to the mass transported. Thus, by removing 70% to 90% of the solids, the required energy, wear and capital costs all decline significantly. The resulting de-sanded slurry is also much easier to transport over long distances. The desanding vessel would be optimally located near the tailings deposition area, which may be an exhausted mine pit, to minimize the total transport distance of the coarse solids. In addition, by removing much of the sand prior to bitumen extraction, a higher quality and lower solids product would be delivered to extraction facilities. This would result in a higher residence time in separation vessels (such as existing PSVs) due to a reduction of flow rate, as a large fraction of flow has been diverted at the desander. In turn, this would result in bitumen yield uplift, as product quality is improved down the entire process stream.
One embodiment of oil sand ore blending is described in more detail with reference now to
With reference now to
Also present within the stockyard 305 is shovel 306 for excavating stockpile 352 and delivering the blended ore to a primary crusher 307, which is shown in
It is understood that more than one stockpile can be present in a given stockyard. For example,
In particular,
Thus, in the stockyard as shown in
In summary, potential benefits of the present invention may include:
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- Multiple dump locations enable fully optimized, well averaged blending of ore from mining;
- Standard equipment can be used;
- Unleashes shovel and ore haul productivity; Shovel & trucks not constrained to the real time production rate of hydro transport; eliminates ‘just on time’ constraints on mining operation;
- Reserve ore (reclaimable when haul trucks are hindered due to inclement weather);
- Simplification of civil works allows system to be positioned, and re-positioned, much closer to the mining face, thereby providing shorter haul distance.
From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention. However, the scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.
Claims
1. A process line for mining and blending oil sand ore, comprising:
- a plurality of shovels for mining oil sand ore at least two separate mine faces, wherein at least one shovel is mining oil sand at a first mine face and at least one shovel is mining oil sand at a second mine face;
- a plurality of haul trucks for receiving oil sand ore, whereby at least one haul truck is receiving oil sand ore from a shovel mining at the first mine face and at least one haul truck is receiving oil sand ore from a shovel mining at the second mine site;
- an open stockyard for blending and stockpiling the oil sand ore, where blending of oil sand ore is managed by each haul truck dumping at a dispatched coordinate on a perimeter of the stockyard; and
- a device which moves the oil sand ore from the perimeter of the stockyard into the stockyard to form at least one stockpile of blended ore.
2. The process line as claimed in claim 1, the open stockyard further comprising a shovel for removing the blended ore from the stockpile to a mobile primary crushing station.
3. The process line as claimed in claim 2, wherein a bucketwheel is used to remove blended ore from the stockpile and deliver to the mobile primary crushing station.
4. The process line as claimed in claim 3, wherein the relocatable crushing station comprises an integral rock crusher and discharge conveyor.
5. The process line as claimed in claim 2, the open stockyard further comprising a second conveyor for receiving the crushed blended ore from the primary crushing station and delivering the crushed blended ore to a slurry preparation plant for preparing and oil sand slurry.
6. The process line as claimed in claim 5, wherein the slurry preparation plant is relocatable.
7. The process line as claimed in claim 5, further comprising a screening assembly for screening the oil sand slurry to form screened slurry.
8. The process line as claimed in claim 5, further comprising a solids removal assembly for removing additional solids from the screened slurry.
9. The process line as claimed in claim 8, wherein the solids removal assembly comprises a semi-mobile desanding assembly.
10. A method for blending at least two different oil sand ores, each oil sand ore having a different grade, comprising:
- providing at least one haul truck for each oil sand ore for delivering the oil sand ore to a designated area;
- mapping out a grid on the designated area indicating locations where each ore sand ore is to be deposited by each haul truck; and
- mixing the oil sand ore in the designated area to form a stockpile comprising a substantially uniform grade of blended oil sand ore.
11. The method as claimed in claim 10, wherein the designated area is a stockyard having a pit and the blended oil sand ore is stored in the pit until needed.
12. The method as claimed in claim 11, further comprising reclaiming the blended oil sand ore in the pit by means of a shovel.
13. The method as claimed in claim 12, further comprising crushing the reclaimed blended oil sand ore in a crusher located in the pit.
14. The method as claimed in claim 13, further comprising conveying the crushed reclaimed blended oil sand ore to a slurry preparation unit.
Type: Application
Filed: Apr 25, 2018
Publication Date: Dec 6, 2018
Inventors: RON CLEMINSON (Fort McMurray), DAN WOLFE (Edmonton), MICHAEL CARNIATO (Calgary)
Application Number: 15/962,908