| 摘要 |
<p>Synthetic bitumens are made from a straight-run asphaltic residue (or mixtures thereof) and a cracked asphaltic residue (or mixtures thereof) by the following process: each residue (or mixture) is separated into an asphaltene-containing fraction and an oil fraction substantially free of asphaltenes, and at least part of the oil fraction from one residue (or mixture) is mixed with at least part of the asphaltene fraction from the other residue (or mixture). The cracked and straight-run residues may have the same or different origins, and the synthetic bitumen produced by the above process may be modified by adding to it some of one or both of the two fractions not employed to form the bitumen in question, i.e. some cracked asphaltene fraction and/or some straight-run oil fraction may be added to the bitumen which comprises a cracked oil fraction and a straight-run asphaltene fraction, and vice versa. The separation of the residues into two fractions may be carried out using a precipitant, e.g. pentane or hexane, and one or more multicyclones, e.g. as described in Specification 935,725. Two examples are described, using a straight-run distillate from a Middle East crude as starting material, and a flow diagram of the complete process is provided.</p> |
