The Management of Mature Fine Tailings and the development of the Consolidated Technique MARIA SOTIR - PowerPoint PPT Presentation

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The Management of Mature Fine Tailings and the development of the Consolidated Technique MARIA SOTIR

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Title: The Management of Mature Fine Tailings and the development of the Consolidated Technique MARIA SOTIR


1
The Management of Mature Fine Tailings and the
development of the Consolidated TechniqueMARIA
SOTIRIOUMay 12, 2004
2
Oil Sands
  • As conventional oil resources are depleted,
    heavy oil and bitumen production are playing
    important role in maintaining Canadas oil
    supply.
  • Oil Sands are deposits of bitumen, a heavy
    black viscous oil that must be converted into an
    upgraded crude oil before it can be used by
    refineries to produce gasoline and diesel fuels.
    Bitumen is a tar-like mixture of petroleum
    hydrocarbons with a density greater than 960
    kg/m3.

3
  • Oil Sands recovery processes include extraction
    and separation systems to remove the bitumen from
    the sand and water. During extraction of bitumen
    from Athabasca Oil Sands an aqueous fines
    suspension called mature fine tails (MFT) is
    produced. Traditional tailings management
    practices involve discharge of the tailings
    slurry onto beaches or into containment cells.
  • Oil Sands Tailings are being disposed of in large
    ponds in which mature fine tailings (MFTs), a
    stable suspension of fine particles in water, is
    formed after many years of settling.

4
MFTs effects on the environment
  • MFTs contain residues of hydrocarbonates that are
    toxic for the environment and living organisms
    and have been found in river water, in sediments
    of the river, in floodplains, in fish and many
    other aquatic organisms.
  • Hydrological and geochemical studies that have
    been performed in the area of Athabasca Oil Sands
    have indicated large quantities of tailings with
    much of sulfide oxidation, high concentrations of
    hydrocarbons and mixtures of heavy metals.

5
  • The existence of these compounds in local waters
    is considered responsible for the death of fish
    and invertebrates and the development of plant
    phytotoxicity in a very large area. Plants
    exposed to metals and naphthenic acids in soil
    and water may show signs of chlorosis or necrosis
    as species survivability and recruitment might be
    lowered.
  • Moreover, the studies indicate problems in the
    amphibians and in aquatic populations that have
    been polluted from naphthenic acids.

6
  • Scientists results indicate that the tailings
    that exist in the water and the soils of the area
    continue to release elevated concentrations of
    metals and other elements to surface and
    groundwater for many years after they have been
    released.
  • The development of CT technology is considered a
    very effective process that aims at the
    separation of MFTs from the water, the monitoring
    and evaluation of environmental and reclamation
    aspects, the vegetation selection and landscape
    reformation and the monitoring and prediction of
    depositional and geotechnical performance.

7
The Consolidated Technique
  • Extraction process tailings are sent to
    hydrocyclones which produce a 70 mineral
    concentration underflow stream. The stream which
    contains 90 of the sand-size particles in the
    ore is mixed with mature fine tailings.
  • The Composite Tailings process involves addition
    of gypsum and of chemical coagulants to slurry,
    comprising of sufficient solids content and clay
    minerals fraction that provoke a shift in the
    coarse fines segregation boundary.

8
  • As a result of the treatment, the slurry mix
    becomes non-segregating during transport,
    discharge and deposition. The product is a
    material containing the coarse and fine grained
    tailings solids from which a particle-free water
    is rapidly released upon deposition.
  • The CT mixture which can be pumped with existing
    tailings pumping systems is deposited in a pond
    where it consolidates into a stable deposit.

9
  • The solids are retained within a homogenous and
    uniform deposit. While these deposits are
    initially soft and require containment, an
    increase in strength to allow a relatively rapid
    reclamation is anticipated.
  • The water released from the CT deposit is
    recycled and used for the plants needs reducing,
    in this way, the energy inputs of the oil
    industry.

10
Benefits of CT technique
  • The implementation of CT process offers many
    significant benefits to oil industry
  • Existing volumes of fine tailings (MFT) are
    reduced
  • Disturbed areas will be reclaimed
  • Public and regulatory concerns expressed
    regarding the long term management of fluid fine
    tailings and tailings management and storage
    costs are reduced.
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