Bitumen Mining & Extraction
A large percentage of Alberta's bitumen is found in relatively shallow oil sands deposits which are produced by surface mining. Overburden is stripped off to expose the bitumen formation. Mining is typically done by huge electric shovels, with the capacity to strip 100 tons in a single pass, which fill massive trucks. These trucks are among the world's largest, typically Caterpillar 797 and 797B trucks, with payloads that range from 240 tons to 380 tons. It would take only two days for a typical oil sands mining operation to completely fill Toronto's SkyDome or New York's Yankee Stadium. The trucks transport the oil sands to the extraction plant where the bitumen will be separated from the sand.
Approximately four tons of oil sands are required to produce one cubic metre of bitumen. The recovery efficiency is high, up to 90%.
Once processed, the sand is returned to the mine pit and the site reclaimed. As part of reclamation, fines from the extraction plant are allowed to settle in large tailing ponds; once water is removed, the fines are used to fill in excavated mine sites.
Surface mining is economically feasible for overburden depths not exceeding 75 metres, but this could increase with rising crude prices. The two oldest and largest such surface mining operations in Canada are the Syncrude and Suncor projects.
New initiatives include:
- Enhancing hydro-transport effectiveness
- Developing means of reducing forces binding bitumen to sand
- Improving the effectiveness of the demulsification process
- Optimizing temperature adjustments and additives in low temperature extraction
- Improving water recycling
- Improving sulphur extraction and hydrogenation and coking of bitumen to produce high quantity crude oil
Transport improvement:
- Hydro-transport of oil sands slurry from mine to extraction plant which replaces conveyor belts and reduces trucking. Partial separation of bitumen from sand occurs in the pipelines which improves project efficiency.
- Natural froth lubricity. This comprises shipment of plant froth by pipeline from the extraction plant to the upgrading plant. The process uses sheaths of water as a sleeve in the pipeline, thereby improving lubricity and eliminating the need to add diluents such as naphtha.
