The present invention relates to a process for separating at least one first material from a mixture comprising this at least one first material and at least one second material, which comprises contacting of the mixture comprising at least one first material and at least one second material with at least one magnetic particle, or contacting of the mixture comprising at least one first material and at least one second material with at least one magnetic particle and at least one surface-modifying substance at the same time, contacting of the mixture from step (A) with at least one surface-modifying substance, if this has not been done in step (A), so that the at least one first material, the at least one surface-modifying substance and the at least one magnetic particle become attached to one another, and separation of the addition product by application of a magnetic field.