Abstract: In a process for cleaning short mineral fibers in which the fibers contaminated with foreign bodies are separated from the foreign bodies, at least starting with a certain size, whereby mechanical damage to the fibers is avoided. For this purpose, the crude fiber material to be cleaned is added to a carrier medium which is set in a flowing motion and subsequently passed along a separation apparatus with at least one slot-like recess in the direction of the longitudinal extension of the recess. Thus, at least part of the carrier medium passes from an upstream side through the recess, together with the fibers, to a downstream side. In this way, a fiber filtrate is produced, of which the degree of purity is solely determined by the width of the recess. The carrier medium mixed with the crude material can be circulated in the cleaning process, with the carrier medium separated from the clean fiber filtrate being continuously returned to said circulation as well.