TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Method: The re-run column overhead stream is added to the alkylation reaction zone and separation zone. A portion of the first olefin is used as the second olefin.A portion of the first isoparaffin is used as the second isoparaffin. The re-run column bottoms stream is separated into an upper phase (50) comprising a major portion of the ASO reaction by-product and lower phase (52) comprising a major portion of the volatility reducing additive. The lower phase is added to the alkylation reaction zone.Preferred Composition: The re-run column overhead stream comprises 90 (preferably 98) wt.% hydrofluoric acid contained in a portion of the alkylation catalyst mixture phase.The weight ratio of the second isoparaffin to the second olefin is 0.01-100, preferably 0.25-5.The alkylation catalyst mixture comprises a volatility reducing additive. The re-run column bottoms stream comprises at least a portion of the volatility reducing additive.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: The volatility reducing additive is sulfone, ammonia, methylamines, ethylamines, propylamines, butylamines, pentylamines, pyridine, alkylpyridines, melamine, and/or hexamethylenetetramine.The isoparaffins are isobutane (preferably), and/or isopentane.The olefins are propylene, butene-1, isobutene, 2-butenes, methyl butenes, and/or pentenes. EXAMPLE - A hydrocarbon feed (53.5 g) comprising (wt.%) propane (5.73), isobutane (18.96), n-butane (5.77), isopentane (3.57), n-pentane (0.07), propene (19.12), isobutene (13.01), butene (9.74), t-dibutene (12.35), and c-dibutene (9.29) was mixed with an acid mixture (56.3 g) representative of an alkylation stripping vessel bottoms stream containing (wt.%) hydrofluoric acid (22.9), ASO (28.1), sulfolane (44.5) and water (4.4).    The mixture was stirred at 1500 rpm at 154-164degreesF. After 5 minutes, the hydrocarbon and acid phases were separated and the hydrocarbon phase was analyzed and showed 22.9 wt.% hydrogen fluoride. The hydrofluoric was 19.4 and 20 wt.% at pre-contact and 15.3 and 29.1 wt.% at post contact, respectively after 2 runs.