In a de-asphalting unit, the crude bitumen is treated with either propane or butane in a supercritical phase to extract the lighter molecules, which are then separated.
ɪn ɐ diːˈæsfɔltɪŋ jˈuːnɪt, ðə kɹˈuːd bɪtˈuːmɛn ɪz tɹˈiːɾᵻd wɪð ˈiːðɚ pɹˈoʊpeɪn ɔːɹ bjˈuːteɪn ɪn ɐ sˌuːpɚkɹˈɪɾɪkəl fˈeɪz tʊ ɛkstɹˈækt ðə lˈaɪɾɚ mˈɑːlɪkjˌuːlz, wˌɪtʃ ɑːɹ ðˈɛn sˈɛpɚɹˌeɪɾᵻd.