Process for increasing Bright Stock raffinate oil production

In a process for increasing the amount of Bright Stock raffinate oil derived from the solvent extraction of deasphalted lube oil involving the steps of:

• (a) extracting a vacuum residuum with a low molecular weight alkane hydrocarbon solvent resulting in a deasphalted lube oil solution and asphaltic residue;
• (b) separating said deasphalted lube oil and said residue;
• (c) separating said hydrocarbon solvent from said deasphalted lube oil;
• (d) extracting said deasphalted lube oil obtained from step (c) with an aromatics solvent resulting in a Bright Stock raffinate oil solution and an extract oil solution, said extract oil solution comprised of dissolved aromatics and recoverable raffinate;
• (e) separating said raffinate solution from said extract oil solution obtained from step (d);
• and
• (f) separating said aromatics solvent from said extract oil solution obtained from step (e);
• in which said improvement comprises the steps of:
• (g) recycling said extract oil from which the aromatics solvent has been removed, obtained from step (f), to step (a) and combining said extract oil with said vacuum residuum in a 10-20 LV %, based on said residuum, prior to said deasphalting;
• (h) repeating step (a);
• (i) repeating step (b);
• (j) repeating step (c);
• (k) extracting said deasphalted oil obtained from step (j) with said aromatics solvent resulting in said Bright Stock raffinate oil and said extract oil, wherein said obtained raffinate is present in a substantially greater amount, based on said vacuum residuum, as compared to said raffinate obtained in step (d).