Notes 20100909.124006 Oil Sands Group Meeting
From SnOwy - Ed's Wiki Notebook
Athabasca Oil Sands
Contents |
Background - Oil Sands
- 2010 august news item: Syncrude had an open pond of oil
- ducks arrived from migration early, landed in oil and drowned
- a lot of public relations issues with oil extraction etc.
- Alberta -- sands, bird deaths
- 3 major oil sand deposits in Alberta
- Athabasca
- Peace River
- Cold Lake
- covers 141,000 km2
- Athabasca -- the only one that can be mined at the surface
- oil sands originally discovered by natives: water proofing water vessels
Oil Sand Composition
- Sand hydrated with a layer of water, enclosed with bitumen film (bitumen is the oily interesting part)
Mining
- 2 main categories
- surface mining
- in situ methods:
- steam assisted gravity drainage (SAGD)
- cyclic steam stimulation (CSS)
- CSS: steam causes bitumen to heat up and be drained off in a parallel tube.
- SAGD: steam is pumped in and remains underground for a day-- bitumen is pulled on top of sand and water
- most frequent methods today are surface mining techniques
- surface mining looks a bit like strip mining...
- area is reclaimed and regenerated as open strip geometry shifts
Bitumen Extraction
- Clark hot water extraction method
- oil mixed with hot water and sodium hydroxide.
- bitumen floats
- siphoned
- upgraded to crude
- water and sand remains in tank
- 3m2 water per 1m2 oil sand
- accumulates toxic materials and other contaminants
- silt sands, clay etc.,
- most dangerous class of compounds: Naphthenic acids
- waste water is settled in old mine pits
Waste Water
- toxic to aquatic life -- not toxic to algae and plants
- roughly one trillion litres of waste water on surface of Alberta
Naphthenic acids
- mixture of cyclic and acyclic compounds
- resistant to natural degradation
- attempted to use wet landscape and dry landscape techniques -- letting the NAs set in the tailings water
- able to break down, but is too slow (compared to current rate of production)
- ozonation?
- phytoremediation -- promising approach
Phytoremediation
- algal culture exposed to NA -- searching for resistant species / species that can degrade NAs
- different concentrations used
- species (23)
- Cyanobacteria
- Chlorophytes
- one Diatom
- variable reactions -- even for species within the same class
- estimate the EC% values for each species
- EC50 used -- similar to LD50, except the range is in cessation of growth, not cessation of life
- values based on logistic regression
- only two species could be curve fit
- basically, there's not enough resolution in the interesting domain of NA concentration
- the logistic curve phase transition occurs right where there isn't enough data
- three species chosen for toxicity and uptake