Method and apparatus for purifying a mixture comprising oil and wax

A method for fractionating a crude mixture comprising at least one oil and at least one wax, the method comprising the steps of:

• (a) performing a pre-fractionation step (2) as a layer crystallization (i) with a crude mixture comprising the at least one oil and the at least one wax or (ii) with a crude solvent mixture obtained by adding prior to the pre-fractionation step (2) at most 100% by weight of solvent relative to the weight of the crude mixture, wherein the pre-faction step (2) is sufficient to prepare a first fraction containing low waxy oil and a second fraction containing low oily wax,
• (b) preforming a first crystallization step (12) which includes the further sub-steps of:
• (b1) performing a first suspension crystallization sub-step (14) with the first fraction containing low waxy oil to prepare a third fraction containing dewaxed oil and a fourth fraction;
• and
• (b2) after the first suspension crystallization sub-step (14), performing a second suspension crystallization sub-stage (14′) with a mixture of the fourth fraction obtained in the pre-fractionation stage of method sub-step (b1) and the second fraction containing low oily wax obtained in step (a) to prepare a fifth fraction containing slack wax and a sixth fraction.