B. Ademodi

Preliminary Studies on the Recovery of Bitumen from Nigerian Tar Sands: I. Beneficiation and Solvent Extraction

Abstract Solvent extraction of bitumen from Nigerian tar sands using toluene has been investigated. Pulverization of the tar sands followed by agglomeration in a mechanical shaker resulted in spherical agglomerates having higher bitumen contents than the mined tar sand. The extent of beneficiation was 4% and 19% for the high grade and low grade sands, respectively Temperature, agitation, and tar sand/solvent (S/L) ratios were found to be significant variables affecting the dissolution of bitumen from the sand. S/L ratio has the greatest effect on extraction efficiency. The rate of bitumen extraction, expressed as extractability η∗ showed great dependence on agitation. About 16- and 15-fold increases in extractability were obtained for SIL ratios of 1/20 and 1/5 respectively for a 2.8 fold increase in agitation At the initial stages of extraction, asphaltene content of the bitumen extracted at 50°C was less than that in the bitumen extracted at 25°C. This finding could have significant implications for the...

Kinetic analysis and modeling of stability of bitumen-in-water emulsion stabilized by polyvinyl alcohol (PVA)

ABSTRACT Description of emulsion stability is an essential aspect of process design and development for separation and production operations. In this investigation, bitumen-in-water emulsions were formed with bitumen contents (CB) of 50% and 70% w/w stabilized in the aqueous solution containing Polyvinyl alcohol and dissolved salt ranging from 0.5% to 3.5% w/w. Water separation under gravity was monitored in real time at isothermal condition. Data collected were used in evaluating kinetic parameters and developing model to predict the stability of emulsions with time. The model was found to adequately predict the emulsion stability under the conditions of the investigation.

An aspect of bitumen emulsification by steam condensation: Effect of formation temperature and bitumen content

ABSTRACT The experiments to form emulsions of bitumen including fine droplets of condensate water were carried out for an average formation temperature range; Tf = 38–69°C and bitumen content; CB = 29–82%. It was observed that the water retention capacity or stability of the emulsions after mild agitation was significantly affected by formation temperature and content of the bitumen. The particle size of water droplets in emulsion decreased with increasing formation temperature. However, bitumen emulsions showed similar shear thinning non-Newtonian behavior in spite of the formation temperature, since water droplets in the emulsions changed under shear flow to smaller size similar to ones formed at the higher formation temperature.

Nitrobenzene De-Asphalting of a Medium-Gravity Crude Residue for Lube Oil Recovery

Abstract Die de-asphalting of vacuum residue of Nigerian medium-gravity crude with nitrobenzene has been studied. Analytical data such as viscosity index, viscosity gravity constant, and molecular weight were used to characterize the residue, while chromatographic analyses of the solvent-free extract and raffinate products provided a measure of nitrobenzene de-asphalting efficiency at different solvent-residue ratios. From these data, it was established that the residue was paraffinic and suitable for lube oil manufacture. At a solvent-residue ratio of 6, a de-asphalted oil yield of more than 70 wt. % was achieved, which is comparable to those often reported for the conventional propane system at relatively higher solvent proportions. In contrast to the observed trend of solubilization power, the selectivity of nitrobenzene toward asphaltic material showed a decrease with increased solvent proportion, resulting in the more desirable raffinate with potentially improved oil composition at lower solvent-resi...