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Mining for Bitumen

Mining for Bitumen

All of Alberta's mineable oil sands is located north of Fort McMurray along the banks of the Athabasca River. In order for mining to be economically feasible, the deposit must be located relatively close to the surface, typically no more than 50 meters deep. Once mined, oil sands is mixed with water to produce a pumpable slurry that can be gravity separated. Learn more about bitumen production from mined oil sands.

About 20% of Alberta's total bitumen reserves are close enough to the surface to be mined. The cut-off depth is technically 70 to 75 meters below the surface, although most mines operate at a depth of less than 50 meters. All oil sands mines are located within the Athabasca Basin, just north of Fort McMurray.

Although exact circuit configurations vary among the operations,  a typical oil sands mining facility consists of the following unit operations:

  • an open-pit (or surface) mine
  • a bitumen production circuit where the bitumen is separated from the solids and water
  • a tailings storage facility or pond, where solids are stored and process water is recovered
  • a tank farm, which holds the required inventories of product and diluent, and
  • a utilities plant, which supplies steam, power and water to the facility.

FROM DIRT TO DILBIT: PROCESS OVERVIEW

Once the mined oil sands is hauled to the processing plant, bitumen is separated from solids and water within the Bitumen Production facility, which consists of 3 basic steps:
  1. Ore Preparation: Hot/warm water is added to the oil sands producing a slurry that can be pumped to the processing plant.
  2. Bitumen Extraction: Bitumen is gravity separated from the coarse solids (mostly silica sand) producing an intermediate bitumen froth product.
  3. Froth Treatment: Solvent or diluent is added to the bitumen froth, reducing the bitumen viscosity and allowing for removal of remaining water and fine solids.

BITUMEN PRODUCTION EXPLAINED



OIL SANDS MINING PIT
  • Typically a truck-and-shovel operation, oil sands is excavated from the mine pit using hydraulic or electric shovels. A typical shovel load of is about 90 tonnes. Mined oil sands normally contains from 7 to 13% bitumen by weight.
  • The oil sands is trucked to the Ore Preparation Plant using large heavy haulers. A typical truck load is about 350 to 400 tonnes. Each truck dumps the oil sands load into hopper, feeding into a crusher or sizer.
  • Oil sands mining operations run 24/7. Once the mine is depleted, the pit is backfilled and reclaimed back to a trafficable landscape.


ORE PREPARATION PLANT
  • Once the oil sands is dumped into the hopper, crushers or sizers break up the lumps of ore, dumping onto a conveyor.
  • The loosely crushed oil sands is then cenveyed to a storage facility, which provides inventory for the mine and process plant.
  • The dry oil sands is then transported to a Slurry Preparation Plant where hot or warm water is added to produce a wet slurry that can be pumped to Extraction. This slurry is roughly 40% water, 8% bitumen and over 50% solids by weight.
  • Oversized material (primarily petrified wood, rocks or chunks of ice) are removed through screening. This oversized material is typically re-crushed and recycled or sometimes rejected to a waste pile.


HYDROTRANSPORT
  • Hydrotransport pipelines connect Ore Preparation to the main Extraction facility. Several heavy-duty slurry pumps are installed in series to transport the slurry.
  • These large-diameter pipelines can be several kilometres long, providing the additional time and shear required to break down the lumps of mined oil sands.
  • As the oil sands breaks down, bitumen is liberated and attaches to free air bubbles, allowing for subsequent recovery in Extraction.


BITUMEN EXTRACTION
  • The oil sands slurry is pumped to a large gravity separation unit, typically referred to as the Primary Separation Cell or Vessel.
  • The bitumen attaches to air bubbles and floats to the top of the vessel and is subsequently recovered to a froth storage tank.
  • The heavy silica sand sinks to the bottom of the vessel and is pumped to the tailings pond for storage and water recovery.
  • The bitumen froth product produced in Extraction contains about 60% bitumen, 30% water and 10% fine solids by weight.


FROTH TREATMENT
  • The bitumen froth produced in Extraction is mixed with a solvent or diluent in order to reduce the viscosity of the mixture.
  • Once the viscosity is lowered, the diluted froth is processed through a series of gravity separation units for the final removal of fine solids and water.
  • Froth Treatment produces a relatively clean bitumen product, containing at least 98% bitumen with residual amounts of water and fine solids.
  • Some facilities produce a very clean marketable bitumen (>99.8% bitumen) sold directly to refineries. Other facilities produce a lower quality product (up to 2% water + solids) that needs to be upgraded.


TAILINGS STORAGE
  • Tailings are comprised mostly of water and silica sand from Extraction, fine solids from Froth Treatment, as well as any unrecovered bitumen and residual hydrocarbons.
  • These tailings streams are stored in a large storage facility, or tailings pond, which acts as a settling basin.
  • Once the solids have settled, clarified water is recycled back to the processing plant for use as process water.
  • Tailings ponds are considered temporary storage facilities. The solids in the ponds are eventually reprocessed so the land can be reclaimed back to a trafficable landscape.


PRODUCT AND DILUENT STORAGE (TANK FARM)
  • Tank farms provide inventory volumes in the event of a process upset. This includes storage of bitumen products and solvent or diluent but can also include inventory volumes of bitumen froth and off-spec material.
  • The diluted bitumen product from Froth Treatment is stored in a dedicated product tank. Some type of diluent is required to reduce the viscosity of the bitumen to facilitate long-term storage or transportation.
  • Depending on the quality of the bitumen, the product is either upgraded into synthetic crude oil or sold directly to market, where it is purchased by high-conversion refineries.


WATER MANAGEMENT
  • Since water is used as a carrier fluid for the oil sands, water management is a critical component of any Bitumen Production facility.
  • About 80-90% of the water used in the plant is recycled from within the process. The balance comes from the Athabasca River.
  • All water that comes in contact with the process is considered process-affected. Process-affected water is contained on-site and recycled.

ACTIVE OIL SANDS MINING PROJECTS

All mine sites are located in the Athabasca Basin, just north of Fort McMurray. The mines strattle both sides of the Athabasca River, where the oil sands deposit is relatively close to the surface. There are currently 9 active oil sands mining operations in Alberta, 8 are in operation and 1 under construction.
NO.
FACILITY
CAPACITY
bbl/day
CANADIAN NATURAL RESOURCES LTD.
2
Horizon Ph. 1
150,000
2
Horizon Ph. 2B
150,000
Horizon Ph. 3
IMPERIAL OIL
16
Kearl Initial
110,000
17
Kearl Expansion
110,000
SHELL CANADA
24
Muskeg River
155,000
25
Jackpine
100,000
SUNCOR ENERGY
30
Millennium
180,000
31
Steepbank
150,000
32
Fort Hills 1
160,000
SYNCRUDE
36
Mildred Lake
150,000
37
Aurora North
225,000
TOTAL CAPACITY
1,640,000

1 UNDER CONSTRUCTION
UPDATED: Oct 24, 2016
SITE MAP: TECHNICAL / OIL SANDS 101 / MINING
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