Recovery of heavy oil from Nigerian Tar sands
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Date
1985
Authors
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Publisher
Obafemi Awolowo University, Ile Ife, Nigeria
Abstract
Solvent extraction of heavy oil from Nigerian tar sands has been investigated using toluene.
Pulverization, followed by sieving of the tar sand resulted in spherical agglomeration of the
tar sand particles. The agglomeration was found to beneficiate the tar sands in terms of increased
percent oil content to the tune of and 13% for the rich and lean tar sands respectively.
The effects of solid/liquid ratio, temperature and agitation on the extraction process were
evaluated factorial experimental design. Extraction. efficiency was found to increase with
increasing agitation speed and cuss transfer driving force, expressed in terms of solid/ liquid
ratio, but decreased with increasing temperature.
Of the three variables, the solid/liquid ratio the greatest effect on extraction efficiency. The rate
of oil extraction, expressed as extractibility showed a great dependence on agitation. Twelve and
thirteen fold increases creases in extractibility were obtained at solid/liquid ratios of 1/20 and 1/5
respectively for 2.8 fold increase in agitation (250 r.p.m to 700 r.p.m).
The asphaltenes content of the heavy oil extracted at 50C was about 12% lower than that of the
heavy oil extracted at 25°C for extraction times below 10 minutes. The implication of this
reduction in asphaltenes level could be very significant in terms of the cost of upgrading the
heavy oil.
Stage-wise extraction gave high extraction efficiency at a low solid/liquid ratio. An efficiency of
about 99 was obtained at a total, solid/liquid ratio of 2/3 w/v (43wt% solid loading) and agitation
speed of 430 r.p.m in a three stage extraction. From an analysis of the power consumed and time
±or extraction, it was found that 440 r.p.m, 26 minutes and 440 r.p.m, 18 minutes could be the
most economical agitation and time levels of operation at solid/liquid ratio- of 1/5 and 1/20
respectively.
Description
175p
Keywords
Tar sand, Heavy oil, Toluene, Pulverization, Agglomeration, Extraction, Agitation, Asphaltenes level